Trainingship TPC/HDT Test Engineering · 2006. 1. 23. · Title: Trainingship TPC/HDT Test Engineering Author: A.J.Baeten Subject: Praktikum Keywords: Grating, Range group, Synchromesh

Internship at DaimlerChrysler Department TPC/PTH

Test Engineering

Upshift grating Shift problem with the range group

Design assignment

DCT Report 2005-144 Date: 13.01.2006 Author: A.J. Baeten Supervisor Tu/e: dr. P.A. Veenhuizen Supervisor DaimlerChrysler: B. Schropp

Tu/e DaimlerChrysler

Index

PART 1: UPSHIFT GRATING ........................................................................................................................... 4

1 PROBLEM DEFINITION ........................................................................................................................... 5

1.1 Introduction......................................................................................................................................... 5 1.2 Assignment .......................................................................................................................................... 5

2 MEASUREMENT PLAN:............................................................................................................................ 6

2.1 Measurement conditions ..................................................................................................................... 6 2.2 Measured signals ................................................................................................................................ 6

3 MEASUREMENT RESULTS...................................................................................................................... 7

3.1 Data representation ............................................................................................................................ 7 3.2 Analyzing the measurements ............................................................................................................... 7 3.3 Grating occurrence ............................................................................................................................. 9 3.4 Conclusion ........................................................................................................................................ 11

4 SUMMARY ................................................................................................................................................. 12

PART 2: SHIFT PROBLEMS WITH THE RANGE GROUP....................................................................... 13

1 PROBLEM DESCRIPTION...................................................................................................................... 14

1.1 Situation sketch ................................................................................................................................. 14 1.2 Assignment ........................................................................................................................................ 14

2 MEASUREMENT PLAN........................................................................................................................... 15

2.1 Desired signals.................................................................................................................................. 15 2.2 Boundary conditions ......................................................................................................................... 15 2.3 The test track ..................................................................................................................................... 15 2.4 Signal processing .............................................................................................................................. 15

3 INTRODUCTION ON TRANSMISSION G131 ...................................................................................... 17

3.1 Gears................................................................................................................................................. 17 3.2 Shift support ...................................................................................................................................... 17 3.3 Interlock System ................................................................................................................................ 19

4 RESULTS OF THE MEASUREMENT.................................................................................................... 20

4.1 Processing the measurement data..................................................................................................... 20 4.2 Interpretation of the data .................................................................................................................. 20 4.3 Conclusion ........................................................................................................................................ 22

5 INTERLOCK FUNCTIONALITY TEST ................................................................................................ 23

5.1 Goal................................................................................................................................................... 23 5.2 Measurement plan............................................................................................................................. 23 5.3 Conducting the measurement ............................................................................................................ 23

6 ELECTRO-MECHANICAL INTERLOCK............................................................................................. 25

7 SUMMARY ................................................................................................................................................. 26

PART 3: DESIGN ASSIGNMENT ................................................................................................................... 27

1 ASSIGNMENT............................................................................................................................................ 28

1.1 Actual method.................................................................................................................................... 28 1.2 Demands for a new measuring method ............................................................................................. 28

2 DESIGN PROCESS.................................................................................................................................... 29

2.1 Ingredients for a new measuring device............................................................................................ 29 2.2 Placing the cone inside the sleeve..................................................................................................... 29

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2.3 Centering the cone and sleeve........................................................................................................... 29 2.4 Adjusting the design for flexibility..................................................................................................... 30 2.5 Attaching the cone to the upper dye .................................................................................................. 30 2.6 Global design .................................................................................................................................... 31

3 DIMENSIONS AND TOLERANCES....................................................................................................... 32

4 FINAL DESIGN.......................................................................................................................................... 34

5 ERROR ESTIMATION ............................................................................................................................. 36

5.1 Error sources .................................................................................................................................... 36 5.2 Play between the cylinders................................................................................................................ 36 5.3 Cylinder is not placed perpendicular ................................................................................................ 36 5.4 The planes on which the sliding collar and cone are placed are not parallel................................... 37 5.5 Misalignment of the vertical cylinder and the bottom dye ................................................................ 37 5.6 Total tolerance .................................................................................................................................. 38

6 RECAPITULATION .................................................................................................................................. 39

LIST OF SYMBOLS .......................................................................................................................................... 40

ACKNOWLEDGEMENT.................................................................................................................................. 41

APPENDIX A: DRIVER A ................................................................................................................................ 42

APPENDIX B: DRIVER B................................................................................................................................. 44

APPENDIX C: GEAR RATIO OVERVIEW................................................................................................... 46

APPENDIX D: SYNCHROMESH COMPONENTS....................................................................................... 47

APPENDIX E: INTERLOCK............................................................................................................................ 48

APPENDIX F: WEIGHT CALCULATION .................................................................................................... 49

APPENDIX G: DRAWINGS ............................................................................................................................. 50

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Part 1: Upshift grating Part 1: Upshift grating

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1 Problem definition

1.1 Introduction A Brazilian driver generally shifts quite different then an average German driver. This is partly caused by different legislation and partly by economic differences between Brazil and Germany. For example; in Brazil the maximum permitted weight of a truck is about 60-80 tons, versus 40 tons in Germany. The Brazilians also drive with less powerful engines of round 260 hp against round 350 hp in Germany, which has economic reasons. The combination of higher weight and less horsepower results in a different shifting behaviour. The Brazilian drivers try to keep the torque interruption as short as they can, because with these high loads, the vehicle might decelerate so much during the gear shift that the engine might stall when the clutch is engaged again. An average German driver will shift more slowly since he has more power at his disposal.

1.2 Assignment While testing in Brazil, the test drivers there had the opinion that grating occurred more often then desired. The origin of this problem is subject of discussion whether the problem lay’s with the driver or the transmission. The goal of the measurements is to gain a better insight and based upon measurement results clarify the origin of the problem.

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2 Measurement Plan:

2.1 Measurement conditions 1. The driven truck is not loaded. 2. Three drivers were driving the truck after another each of them shifting different. Two of the drivers are

from Germany and the other driver is one of the Brazilian test drivers. 3. The split group will not be used. 4. They will shift up sequential starting in first gear and then shift down again.

2.2 Measured signals The following signals will be measured: 1. Rotational speed of the outgoing axle 2. Shift force at the shift lever 3. Ingoing number of revolutions at the transmission 4. Position of the shift lever Signal 1 is measured by placing a toothed disc at the outgoing axle of the transmission. With this extra disc and a Hall sensor the rotational speed is measured analogue. Signal 2 is measured with a sensor that is fitted onto the shift lever. The output of the sensor is in volts and it can measure force in three directions. In this measurement only the shift force is important, so only one direction will be observed. Signal 3 is obtained from the a build-in sensor inside the transmission. The shift lever position, signal 4, is measured directly at the transmission. This signal was measured using an inductive sensor that can measures a translating movement. However the shift movement at the transmission is a rotation, so the value obtained by the signal is not entirely correct. Therefore the position of the shift lever is not in mm but without unity. With the chosen signals grating of the transmission can be seen very clear in the figures we will see later on in this report. The shift force can be plotted over the shift lever path, with such a picture the progression of a gear shift can be monitored clearly. The progression of shifting into gear becomes very transparent with the help of such figures. With the signals that contain the rotational speeds of the ingoing and outgoing shafts, the effective change in rotational speed can be observed. When this signal is plotted against the shift force in which phase the gear shift is at a certain shift lever position.

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3 Measurement results

3.1 Data representation

Figure 1: example

In the figure above the rotational speed of the in- and outgoing axle are plotted with respect to the gear chosen at the end of the gearshift. The large peaks in the blue signal, called „Hauptwelle“, are caused by the low number of revolutions of this axis, they are just disturbance and have no relation with the real input. The black line named „Schaltkraft“ represents the shift force, this force is exerted on the shift lever when shifting into gear. The green line called „Losrad“ is the rotational speed of the free rotating gearwheel. The „Schaltweg“ is the position of the shift lever, however the numbers on the vertical axis are without unity. The difference because of the measuring error however is quite small. Right up in the middle of the figure is shown which gearshift is made, so in this case there was shifted from third gear into fourth gear. The letter L standing behind the numbers three and the four indicates that the split group was in the slow group (L stands for „langsam“, meaning slow). At the bottom left corner of Figure 1 the name of the driver and the name of the source file are stated.

3.2 Analysing the measurements Now it is clear what is shown by Figure 1 and what the individual lines are meaning, we can discuss some measurements that appear to be a good indication of the differences between the shift behaviours of the different drivers. These measurements are shown in Figure 2, the gearshift of the German driver, and Figure 3 which shows the gearshift of the Brazilian driver. These gearshifts are representative for the measurements taken and do not show exceptional behaviour. From the figures the difference in shift behaviour can easily be observed. When we take a look at the shift force we can see for instance that the shift force of the Brazilian driver was higher then of the German driver. Being roughly 200 N for the Brazilian driver as can be seen in Figure 1 and Figure 3 versus roughly 115 N for the German driver. Another difference is that the main synchronisation phase is much shorter with the Brazilian driver, this however is obvious because the shift force is much larger. Another thing is that the rotational speeds are lower when the Brazilian driver makes a gear shift. This means that the kinetic energy is lower at the start of the gearshift so less work is needed to overcome the difference in rotational speed.

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When we take a look at the rotational speed of the outgoing axle we can see something very interesting. Especially in Figure 1 it is obvious, but it is also present in Figure 3: during the main synchronisation phase the rotational speed of the outgoing axle of the gearbox is increasing! This is quite unexpected and is also not desirable. When we look at Figure 2 we can see that this phenomenon is not present here.

When we take a look at the rotational speed of the outgoing axle we can see something very interesting. Especially in

Figure 1 it is obvious, but it is also present in Figure 3: during the main synchronisation phase the rotational speed of the outgoing axle of the gearbox is increasing! This is quite unexpected and is also not desirable. When we look at Figure 2 we can see that this phenomenon is not present here.

Figure 2: Gear shift of German driver

Winding of rear axles

Figure 3: Gear shift of Brazilian driver

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After this some measurements were done in Brazil on the original vehicle which transmission led to the complaints. A typical gearshift made with this vehicle can be seen in Figure 4. Here the same phenomenon is present as in Figure 1 and Figure 3. The blue line in Figure 4 represents the number of revolutions of the outgoing axle. During the main synchronisation phase, the rotational speed of the outgoing axle is also increasing.

After this some measurements were done in Brazil on the original vehicle which transmission led to the complaints. A typical gearshift made with this vehicle can be seen in

Figure 4. Here the same phenomenon is present as in Figure 1 and Figure 3. The blue line in Figure 4 represents the number of revolutions of the outgoing axle. During the main synchronisation phase, the rotational speed of the outgoing axle is also increasing.

185.2 185.3 185.4 185.5 185.6 185.7 185.8 185.9 186 186.1 186.2Time (s)

0

500

1000

1500

2000

2500

3000

3500

4000

Dre

hzah

l (U

/min

)

75

100

125

150

175

200

225

Weg

(mm

)

-250

-200

-150

-100

-50

0

50

100

Scha

ltkra

ft (N

)

_ __ Getriebe ingang_ _ e_____Getriebeausgang

NTC1933S33_52D, G211 - FZ:196820, Schaltung von Gang 3 nach 4Ivair / RoselyTAS3 - 03/06/04Datei - NTC1A

ratschende Schaltung

_____Kupplungpedalweg_____Schaltweg

_____Motordrehahl

Winding up of rear axles

Figure 4: Measurement made in Brazil

The winding of the outgoing axle occurs in the axles between the differential and the rear wheels. With the Brazilian truck the axles were not of the same type as from the German truck. The Brazilian axles were weaker, meaning that the outgoing axles can wind up even more easily. It is already mentioned that the winding of the rear axles is undesired, however why that is, is not mentioned yet. The reason is that when the rear axle winds up during the main synchronisation it relaxes again when the synchronisers are not able to conduct torque. This occurs in the free flight phase that follows after main synchronisation. After the gear was synchronised and at the moment it enters the free flight phase the rear axles can relax and they will unwind. This results in a vibration of the rear axle and this vibration is passed on to the gearbox. These vibrations lead to an extra large difference in rotational speed of the in- and outgoing axle of the gearbox the chance the transmission will make a grating noise is bigger.

3.3 Grating occurrence In the following table an overview is made in which gear shift grating occurred and in which ones didn’t. This is done for a German and the Brazilian driver for the measurement data collected in Germany. From Table 1 it becomes clear that the gearbox grates quite often and that grating occurs more often with the Brazilian driver. The letter R in Table 1 indicates that the grating occurred in that gear shift where driver A is the Brazilian driver and driver B is the German driver.

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dat file 1.dat 2.dat 3.dat 4.dat 5.datName fahrer R A1L->2L A A A R(A) R 2 32L->3L Rn R An A An 2 33L->4L A A R R R 2 34L->5L R A A Rh 2 25L->6L A A R R(A) 2 26L->7L R(A) A R(A) Rh Rh 2 37L->8L A R(A) R R Rn 3 2Name fahrer1L->2L A R 1 12L->3L A(R) R A(R) 1 23L->4L R R Rh A R 4 14L->5L A A Rh Rh 2 25L->6L A A A 0 36L->7L A R Rh R R 4 17L->8L R A(R) A A 1 3

Bemerkungen Hauptsynchronisation dauert bei Jörg viel länger wie bij Marcelo.In diese Zeit ändert die position von der Schalthebel sich nicht.

A 1 Piek nach hauptsynchronisation, wobei die zähne einander treffen und der synchronring abgeweseR Ratschen, mehrere Pieken nach Hauptsynchronisation(...) Kann auch ... Sein, nicht deutlich.h Höhe Pieken, also höhe Kraftn Niedrige Pieken, also niedrige Kraft

Jörg

MarceloScore

Schaltübersicht

Table 1: Grating overview In Table 2 some shift times are represented. Shift times were compared for gearshift 6L to 7L and Table 2 was made with the help of Figure 5 and other similar figures that are made for each test session. This specific gear shift was chosen because the measurements are free from disturbance.

Free flight

Several peaks indicates grating

Speed difference

Main synchronisation

Figure 5: Definitions

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dt synchron dt freiflug dt synchron dt freiflugdat 1 0.123 0.078 0.136 0.066dat 2 0.135 0.073 0.098 0.08dat 3 0.114 0.057 0.122 0.079dat 4 0.142 0.085 0.15 0.104dat 5 0.182 0.127 0.149 0.101

Jörg Marcelo

Table 2: shift time characteristics

What is remarkable is that the synchronisation times of driver A are not significantly lower then those of driver B. This is unexpected because driver A exerts a higher shift force onto the shift lever and shifts at lower engine speed. This means that he does more work while he actually would need less work to synchronise, but his shift times are about equal to driver B. Free flight phase times from both drivers are also approximately equal. Again it would be more logical if the free flight times of driver A were be shorter. Shifting with high force and as possible didn’t bring driver A much according to Table 2. In the next table the differences in rotational speed that occur during the free flight phase is shown. Table 3 was created from the measured data that was presented like in Figure 5.

dat name differenzdrehzahl besch losrad x = ratschenhauptsynchronisierung zweiten punkt

j1h11n13b 55 55 10j2h11n13b 50 31 8 xj3h11n13b 71 55 13j4h11n13b 50 57 12 xj5h11n13b 55 36 7 x1h11n13 46 33 9 x2h11n13 42 36 83h11n13 45 40 7 x4h11n13 37 52 11 x5h11n13 42 32 8 x

Table 3: difference between rotational speed of in- and outgoing transmission axle

In Table 3 the differential speed is almost always more then 10 rpm lower with the Brazilian driver, this means that it is likely that his gearshifts will grate less often. When we look at Table 1 however, then this is not the case (gear shift 11 to 13 corresponds with gear shift 6L to 7L).

3.4 Conclusion The shift times in Table 2 and the difference between rotational speeds of the in- and outgoing axles of the gearbox in Table 3 do not correspond with what we have seen in the grating overview in Table 1. The reason that grating occurs so often with driver A must lie in the way he operates the gearbox. This often results in the rear axles winding up instead of the axles inside the transmission slowing down. The extra vibrations which are a result of this phenomenon are to blame for the grating. In Appendix A: Driver A and Appendix B: Driver B we can see that the vibrations in the gearshifts of driver A are quite a bit larger then those of driver B. These vibrations occur especially with shifts in lower gears.

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4 Summary Shift behaviour between the two drivers differs very much. The German driver shifted relatively slow, giving the gearbox time to do its job. The gearbox was first taken out of its gear, then a new gear was selected and after that the driver shifted into gear. With the Brazilian driver this was done in one movement because he wants to keep torque interruption as short as possible, he shifts relatively fast without making a clear distinction between the different shift steps. The reason that grating occurs so often is caused by the fact that shifting is done too quick and the corresponding force is so high that the rear axles start too wind up, resulting in a vibration that interferes with the synchronisation. A solution would be to make stronger axles.

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Part 2: Shift problems with the range group

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1 Problem description

1.1 Situation sketch A test truck is fitted with a new transmission in which several modifications are made. The housing has a slightly different form, including a new breather valve, and a new friction material on the synchronisers. When the range group is shifted a certain noise, which sounds like two metal parts that hit each other, is heard. One possible source for this noise is a built-in protection for the range group, called the interlock. The function of the interlock is to prevent engaging a new gear as long as the range group is not done with shifting. It is possible that the range group shifts too slow compared with a gear shift of the basic gears.

1.2 Assignment The goal of this assignment is to find out what causes this noise and how this problem can be solved. First a measurement plan that is capable of finding the problem. It must list what signals are necessary to investigate this problem and that are likely to produce clear results. Then the conditions under which the measurements are made will have to be defined. Secondly the results will have to be processed and analysed and see if the hypothesis that the range group shifts too slow is correct. If necessary a new measurement must be defined.

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2 Measurement plan

2.1 Desired signals First it is important to determine what signals will be useful and give the right information about the shift progress to come up with a good solution for the problem. Because of the symptoms described in the situation sketch extra attention will be paid to the range group. The most interesting signals are: 1. The in- and outgoing rotational velocity is in any case desirable, from these two signals can be derived from

which gear to which other gear was shifted. It is also crucial to see when the difference in rotational velocity is zero for the first time, because this means that the gear is synchronised and it should be possible to shift into a certain gear. For outgoing rotational speed the tacho signal was used. By determining a factor that can be measured when driving in direct gear, the tacho signal can be translated to represent a rotational velocity. In- and outgoing rotational speeds must be equal in direct gear and by dividing the ingoing rotational velocity through the speed, this factor can be obtained and later multiplied by the speed signal to obtain the angular velocity of the rear axle.

2. Too visualise if the range group has shifted, the displacement of the shift cylinder must be known, so a displacement sensor is connected to the piston inside the shift cylinder of the range group. Further the pressures on both sides of the cylinder are measured to have an idea what forces are acting on the shift cylinder.

3. To detect if the driver is experiencing any irregular resistance while shifting, the shift force at the shift lever is also measured. If some component in the transmission would block or hang itself, then this can be seen as a peak in the shift force. The force is measured in 2 directions x and y, where x is for the shift direction and y for the selection direction.

4. The clutch position might also be of some interest to see how long the total gearshift took. This data can be obtained very easily from the CAN bus of the vehicle.

5. Another interesting parameter which has a large influence is the transmission oil temperature, especially when the engine is just started and the oil is still cold. This signal can also be retrieved from the CAN bus.

The signals coming from the pressure sensors and the position of the piston that operates the range group are sent to the laptop using an A-D converter. This converter is produced by the company SENG and will be called the Seng-box from now on. The other signals are retrieved from the CAN-bus. This is done by connecting the Vector CancardX, which can be fitted into a PCMCIA slot of the laptop, and can then be connected through a Y-plug to the CAN-bus of the truck. To make it possible for the program to read these signals, a DBC-file must be loaded into the program DIAdem. Now the desired signals can be picked from a list. This list however is coded, so to be sure you pick the right signal, the signal code name must be looked up in a catalogue.

2.2 Boundary conditions • The truck must be loaded to stress the transmission. • The truck must be driven on a plain road as well as on steep roads to determine when grating occurs. • To measure a lot of shifts of the range group, the test track shouldn’t be too fast. When driving in the city for

example, the range group must be shifted quite often.

2.3 The test track To make sure there will be shifted a lot from the large to the small range group, the driver will drive mostly in the city and its surroundings. The test will start at 14:00u and it will last till 19:00u. The route is a prescribed route often for truck testing. This route has, besides driving in the city, quite some steep climbs in it. This could be interesting because the driver is likely to shift faster on a slope to keep the torque interruption as short as possible. In these conditions the range group will have to shift fast because the drivers wants to shift into the next gear as quick as possible to prevent engine stall.

2.4 Signal processing The signals are collected and processed using the program DIAdem. In this program signals coming from different sources can be measured and saved as well as shown during the measurement. The sensors can be calibrated individually in this program in several ways. This can be done in a diagram in which can be prescribed

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how the signals are retrieved and what kind of output is preferred. Function blocks can be connected with each other to lead the data from the input to the different outputs. In the following figure a screenshot of such a diagram is shown.

Figure 6: Screenshot DIAdem

Explanation of the function blocks in Figure 6. • Takt200: Indicates the measurement frequency in Hertz. Here a frequency of 200 Hz is chosen. • Kältemessung: Input from the analogue signals. • AxB1: A 2 point calibration including an offset and a factor to correct the signals of the sensors. • Attrappe: Displays the values of some signals real-time. • Binär1: A led on the laptop screen lights up if the button is pressed. • Speichern1: All data from the signals is collected here. • Flanken1: If the value of a certain signal crosses a certain value the output of this block becomes „1“. • Flanken2: Ditto as flanken1 with the difference that when the signal drops below a certain value the output

becomes „1“. • Oder1: If one of the two incoming signals has value „1“, the output of the oder1-block becomes „1“ as well. • Oder2: Ditto as Oder1. The shown diagram is equipped with a trigger, a measurement of 6 seconds is automatically started if the pressure on one side of the piston inside the range shift cylinder changes. In this program it is possible to use certain values that specify how long the data from before and after the trigger event should be saved. Here a period of 3 seconds before and after the trigger event is chosen. This value is based upon tests done on the test track from Daimler, and with these values the entire gearshift from the moment of opening the clutch till closing the clutch is measured. Besides the trigger function there is also an option added to start a measurement of the same length as when a measurement is started by the trigger, by pressing a button. This is done to be able to react on unforeseen shift errors or other unexpected events. This button can also be used to mark a measurement too make it easier to find that particular measurement back afterwards. The signal of the button is also measured and varies from zero to one and a half volts. When the button was pressed, the raise of the signal can be looked up in the measurement, this way it is possible to find any special event again.

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3 Introduction on transmission G131 3 Introduction on transmission G131

3.1 Gears 3.1 Gears In this chapter the lay-out of the transmission in the test vehicle will briefly be introduced. In Figure 7 a schematic drawing of the gearbox is represented. As we can see in this figure the gearbox does not have a split group. It has four basic gears and a planetary gear, this results in a total of eight gears, the gear ratio’s can be found in Appendix C: Gear ratio overview.

In this chapter the lay-out of the transmission in the test vehicle will briefly be introduced. In

Figure 7 a schematic drawing of the gearbox is represented. As we can see in this figure the gearbox does not have a split group. It has four basic gears and a planetary gear, this results in a total of eight gears, the gear ratio’s can be found in Appendix C: Gear ratio overview.

Figure 7: G131 schematic

3.2 Shift support The shift-lever is hydraulically connected with the gearbox and the gearshift is pneumatically assisted, Figure 8 is a schematic representation of this system. This system was chosen because the driver still gets feedback and can feel what is happening inside the transmission through the shift lever. With this system it is also possible to aid the driver when shifting into a different gear by air pressure, practising an extra pneumatic force onto the shift cylinder, so the transmission requires a relatively low force to shift.

C,2,4,6,8 R,1,3,5,7

G

Schaltübersetzung (G131) I = 7,6 Länge Schalthebelwelle IHW = 53 Länge Schaltfinger ISF = 34

Figure 8: Working of HPS2

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The link between force acting on the shift lever and force that is acting on the collar sleeve is represented in Figure 9. If this figure was representive for the real implementation, it would be easy too determine the total force acting on the sliding collar.

Figure 9: Desired link between shift force and force at collar sleeve

The forces in the figure above however represent the desired linkage between shift force and force acting on sliding collars. It is based on the maximum force the synchronisers can handle. In practise the linkage is not degressive like in Figure 9. In the figure below, the correlation between the hydraulic and pneumatic pressure and the shift force is shown. Here p_Hydr_eff is the effective hydraulic pressure, p_Pneum_eff is the effective pneumatic pressure and Schaltkraft_X is the shift force.

Figure 10: Pressure and force progress

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The vertical axis in this figure is named „Effective pressure [bar]“, but the effective pneumatic pressure is also scaled with respect to this axis. This measurement was not made with the test vehicle used for the other measurements, however the tested vehicle was also equipped with the HPS2 system, so the results can also be applied to the tested transmission. The forces acting on the collar sleeve can be calculated based on the information in Figure 10. The equations to convert the data from the figure into a force are not the same for the even and the uneven gears. This is because the surfaces inside the shift cylinder are not the same, this is shown in Figure 8. The force for the uneven gears can be calculated with:

( ) flpoddpoddhoddhoddodd llPAPAF /,,,, ⋅+⋅= Equation 1

When we fill in the matching parameters we find:

( ) ( )( ) ( ) ( )( )( ) 3453

,23

423

4,23

423

4 102510631081022 poddhoddodd PPF −−−− ⋅−⋅+⋅−⋅= ππππ Equation 2

The same formula can be applied to the even gears, only the surfaces have different values:

( ) ( ) ( )( )( )3453

,23

423

4,23

4 10810631022 pevenheveneven PPF −−− ⋅−⋅+⋅= πππ Equation 3

The highest force is reached at the orange line, here both the hydraulic and pneumatic pressure are on their highest point. The hydraulic pressure is 4,6 bar or 4,6·105 Pa and the pneumatic pressure is 0,6 bar which is identical to 0,6·105 Pa. Unfortunately it is unknown if the data that was used to make Figure 10 was an even or an odd gear shift. Since it is unknown we will assume it is an odd gear shift. The resulting force can now be calculated using Equation 2. Substitution of the pressures gives a total force of approximately 482 N. Table 4 shows the individual contribution of the hydraulic and the pneumatic parts.

Hydraulic force 236.534207Pneumatic force 245.642978Total force 482.177184

Force acting on sliding collar [N

Table 4: Shift force

These forces however are peak forces and the value of the available force fluctuates over time. It should also be mentioned that different gearshifts can result in a different value of the pneumatic force. The pressure is not controlled, so the longer a gearshift takes, the more time the pressure has to build up. If we take a look at Figure 10 again, we can see that a very large dip in the shift force and hydraulic pressure occurs. This is because the gears are synchronised and it is possible to proceed too the locking phase. The shift cylinder can move freely during the transition of these phases and due to the high force at the start of this phase it accelerates fast. Because it is much lighter then the shift lever and its hydraulic system it can be seen in the figure that the lever cannot follow. We can also make a comparison between a real measurement as in Figure 10 and the desired force linkage seen in Figure 9. The shift force at the orange line is 65 N which should correspond with a force at the sliding collars of approximately 950 N according to Figure 9. When we look at the force that follows from the measurement we must conclude that this force is much lower, 482 N. From the comparison we can conclude that the differences are very large. Since the actual implementation is quite different from the desired or maximum force as in Figure 9, we will not use this figure to estimate the forces acting on the sliding collar. Further on in this report we will see why this information is relevant.

3.3 Interlock System Since the interlock is suspected to cause some of the problems, its components can be seen in the Appendix E: Interlock. The Interlock is activated in the case that the driver tries to engage the selected basic gear before the range group has shifted. Since the range group is operated pneumatically without any feedback, the driver does not know if the shift action has completed. Too protect the synchroniser of the range group from getting damaged. For example if the driver has shifted the basic gear and accelerates again while the range group is still shifting. If this would be possible the range group would be seriously damaged.

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4 Results of the measurement

4.1 Processing the measurement data The measurements have been conducted and will now be presented and analysed. A very typical measurement can be seen in Figure 15. The collected data must first be converted to represent the desired signals correctly. The rotational speed of the outgoing axle must be converted into the rotational speed of the primary axis and the rotational speed of the ingoing axle must be converted into the rotational speed of the free revolving gearwheel. To be able to make this conversion, the active gear must be known, then it is easy to find the corresponding gear ratios. A sheet with an overview of gear ratios of this transmission can be found in Appendix C: Gear ratio overview. The data is always scaled with respect to the newly chosen gear and not to the active gear at the start of the measurement.

Figure 11: Typical up-shift

When the signals are in the desired format, a graphic can be made to show the results. On the horizontal axis the time is represented, further there is decided to place two graphics in one figure too reduce the number of lines in each figure. The axis that represents the rotational speeds of the primary axis and the free gearwheel are always chosen equal. Further the window length is always of the same length, which is chosen in such a way that it is the narrowest fit that can contain all measurements. This is done to make it easy to compare different gearshifts with each other. In the upper left corner of the figure a small window shows the initial and the final gear as well as the name of the driven truck and the file name that contains the data.

4.2 Interpretation of the data After editing the signals, they can be interpreted and the gearshifts can be compared with each other. What can be noticed in all figures, is a certain force peak before main synchronisation takes place. This peak is indicated in Figure 12 with the orange circle and the subscription „first peak“.

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first peak

Axes synchronised

elasticity

Figure 12: Measurement with strange peak

At t ≈ 91,5 s the initial gear is taken out according to the first peak in the shift force (black line). A mechanical valve is following a certain profile and at a certain position it provides the range shift cylinder with pressured air. This can be seen in the top graphic and in this measurement the light blue line rises towards system pressure. The vertical axis with the same colour is called „druck l“, meaning that if the pressure in that part of the shift cylinder is raised, the slow group is selected. Then the selection of a new gear starts, this is indicated by the peak in the selection force (red line). At the yellow line the range shift takes place, there is no extra peak in the selection force due to the shifting of the range group, since the range shift is actuated by pressured air and is mechanically completely decoupled from the shift lever. After selection, the driver shifts into the new gear. We can see this because the shift force is rising at t ≈ 92,5 s, in this case there is almost no overlap between shifting and selecting, from which we can conclude it was a steady gear change. At the orange line the range group is done shifting from the slow to the fast group. The shift force keeps rising till the peak right after the orange line contained by the orange circle, here the shift force caves in. It is unclear what causes this peak in the shift force. There are several possibilities: 1. The peak is caused by the circlip in the synchroniser ring (see Appendix D: Synchromesh). 2. The force is caused by a malfunctioning of the interlock system. We will come back to this point later on in this report. As long as the turquoise line is tangent to the blue line, representing the free turning gearwheel, this gearwheel is decelerated by internal friction of the gearbox. The internal friction is composed by oil drag, friction in the bearings and friction caused by the interconnection of the gearwheels. Then the blue line starts to decline faster, this means that the main synchronisation has started. At the brown line the gears are synchronised, now the sliding collar can move further towards the locking phase. The shift force breaks together because the sliding collar is suddenly free to move further without opposite force. Within the brown circle it can be seen that a new difference in rotational speed originates. This is possible because the sliding collar hasn’t made a form closed connection between the synchroniser body and the synchroniser ring. This difference is neutralised when the gear tooting of the sliding collar and synchroniser ring strike each other. When this difference in rotational speed is too large, it becomes noticeable as a grating noise. This phenomenon is therefore called „grating“.

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Another interesting thing can be seen in the top graphic, namely a small peak in the pressure of the slow range group. This occurs because the both channels of „druck l“ and „druck s“ come together in one air releasing channel. When opening the valve to release pressure from „druck s“ air can also flow towards the point where the pressure of „druck l“ is measured. Actually it can then be represented by a single chamber with some restrictions. Finally there is a last peak in the shift force in the green circle. This is because the sliding collar is at its end position, the synchroniser body and synchroniser ring are locked. This means that the shift lever cannot move any further, meaning that the impact of the sudden stop causes this last peak.

Number of shifts with noise3.dat 49 144.dat 47 145.dat 11 36.dat 19 5

126 36

Testdrive of vehicle 950v131 for gear change of the range group

Table 5: Number of shifts with noise

The graphics used to make this table are not included in this report because it would take too many pages.

4.3 Conclusion In Figure 12 we can see that the hypothesis that the range group wouldn’t shift fast enough, is obviously not correct. The range group is done shifting before main synchronisation takes place. The largest angle of inclination of the dark blue line is reached some time after the range group has reached its new position. It is not possible to make a good judgement on what is causing the uncomfortable gearshifts. If the shift lever position was also measured then this could have provided interesting information. According to these measurements the first option, that the range group shifts too slow, can be rejected. The other option was that the circlip caused the first peak. This would be a possibility because the force peak can be found in all measurements. The force needed to overcome the circlip is 260 N. Results of the calculations based on information in Figure 10 is shown in Table 4. They show that a force of roughly 480 N is exerted on the sliding collars when the force on the shift lever is roughly 60 N. The height of the first force peak is always roughly 60 N. This force is much higher then the force necessary to overcome the circlip. The only option that remains is that the Interlock system causes the peak. In the next chapter a new measurement will be formulated and conducted to test the functionality of the interlock system. New tests will provide more clarity concerning the functionality of this system.

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5 Interlock functionality test After the previous measurements the suspicion that the Interlock does not function correctly has grown. Assumed is that it may hang itself, so that it is unable to unlock the shift cylinder at the right time.

5.1 Goal Find out if the Interlock really hangs itself and which part of the interlock is causing this.

5.2 Measurement plan The transmission that was build-in at the vehicle during the measurements will be removed. Too test the functionality of the Interlock it will be put onto a table, a spare shift lever will be coupled to the transmission too operate it. If fast gearshifts are made with the shift-lever, the Interlock will likely hang itself, like in the vehicle. By removing certain plugs from the transmission the axles of the Interlock can be observed. It is also possible to use a tool like a screwdriver to detect in which position the axes are. This way it is possible to see which part of the Interlock causes the problem. To approximate the build-in situation as good as possible air support will be available when shifting, just like in the vehicle. This is also required to exert the same forces onto the sliding collars as in build-in conditions, these forces cannot be achieved by hand force only.

5.3 Conducting the measurement During several attempts with fast gearshifts, the lever was stuck. When this situation occurred, the force on the lever was maintained. This was done since the lever can be shifted into the selected gear when the force is cleared and then applied again. While applying force onto the lever, the second person checked the position of the axes of the interlock. They were in the right position, meaning they didn’t block the lever movement. However it was not possible to check the position of all axes, so there is a possibility that the bolt which is positioned directly at the shift cylinder, hangs itself. After this first manual test the gearbox was equipped with the following sensors to record a gear shift; - Position sensor range group - Position sensor Interlock - Selection position shift cylinder - Pressure sensor range group forward - Pressure sensor range group backward When the sensors were in place some fast gear shifts were made again to force a lock-up. The results of this test can be seen in Figure 13. Before the transmission was equipped with the sensors, interlock parts 1 and 2 (see Appendix E: Interlock) were taken out of the transmission. The surfaces that slide over each other were polished and greased to decrease resistance. The parts were build in again, however the modifications had no results. These facts, in combination with the peak in the light blue circle that indicates that the shift cylinder moves a bit when the interlock moves towards its end position, arose the suspicion that the bolt that slides into the shift cylinder might be blocked. Maybe the shift cylinder was rotated too far so that the bolt could not get into the groove. Therefore the shift cylinder was taken out of the transmission for visual inspection. As we can see in Figure 14 the shift cylinder is obviously damaged on the edges of the groove. The bolt that fits into the shown groove also shows signs of wear. Apparently the shift cylinder rotates before it can be locked by the interlock´system. Since the interlock is driven by the range group we can draw the conclusion that the range group moves to slow when making fast gear shifts. Probably this is caused by a restriction at the side of the cylinder where air flows out. From Figure 13 we can see that this is the case since the pink line shows the air on the compression side reaches higher pressures then on the expansion side. This is because the air flow is restricted. The restriction cannot be made wider, since it serves as a protection for the synchronisation process. If the restriction would not be placed, the velocity of the shift cylinder would be so high that it would damage the parts of the synchroniser on impact. The best way to solve this problem would be to make the range group cylinder faster. This could be done by making a variable restriction that only slows down the range group when it is near its synchronisation position. Another solution would be to adjust the interlock system as in chapter 6: Electro-mechanical Interlock. However this would have to be newly developed and tested. An easier solution would be to make the groove a bit wider and the bolt somewhat sharper.

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Lock-up

Figure 13: Interlock lock-up

Figure 14: Damaged shift cylinder

24


6 Electro-mechanical Interlock 6 Electro-mechanical Interlock Because of the problems and the large mechanical construction of the interlock system, it would be desirable to see if it is possible too perform this action in a different way, providing the same level of safety. It appeared that there is also another bolt present in the transmission that can lock the shift cylinder. This bolt is controlled electronically. It would be possible to use this bolt to lock the shift cylinder in the same situations as the mechanical interlock does now.

Because of the problems and the large mechanical construction of the interlock system, it would be desirable to see if it is possible too perform this action in a different way, providing the same level of safety. It appeared that there is also another bolt present in the transmission that can lock the shift cylinder. This bolt is controlled electronically. It would be possible to use this bolt to lock the shift cylinder in the same situations as the mechanical interlock does now. To keep things simple and cheap to manufacture the following things are important: To keep things simple and cheap to manufacture the following things are important: 1. Use sensors that are already present in the transmission. 1. Use sensors that are already present in the transmission. 2. It must be possible to build the controller using switches only. 2. It must be possible to build the controller using switches only.

MV-L

MV-R

MV-Lock

+ GN

Neutral

Shift-lever-L K3

Shift-lever-R K4

Position Piston-L

Position Piston-R

D

Figure 15: Electrical interlock Figure 15: Electrical interlock

In Figure 15 we can see an example of how such a controller could look like. The mentioned requirements are both satisfied. The switches in the figure have the following functions: In

Figure 15 we can see an example of how such a controller could look like. The mentioned requirements are both satisfied. The switches in the figure have the following functions:

• Neutral: Detects if the shift lever is in neutral position. • Neutral: Detects if the shift lever is in neutral position. • Shift-lever-L K3: A switch on the lever to detect if the slow group is selected. • Shift-lever-L K3: A switch on the lever to detect if the slow group is selected. • Shift-lever-L K3: Switch that detects if the fast group is selected. • Shift-lever-L K3: Switch that detects if the fast group is selected. • Position Piston-L: Detects if the piston in the shift cylinder has shifted to the slow group, then it opens. • Position Piston-L: Detects if the piston in the shift cylinder has shifted to the slow group, then it opens. • Position Piston-R: Detects if the piston in the shift cylinder has shifted to the fast group and opens if so. • Position Piston-R: Detects if the piston in the shift cylinder has shifted to the fast group and opens if so. The controller fulfils the following functions: The controller fulfils the following functions: 1. The controller makes sure that the shift cylinder of the range group is shut down when the desired position is

reached. 1. The controller makes sure that the shift cylinder of the range group is shut down when the desired position is

reached. 2. The cylinder can only be locked when the shift lever is in neutral position. 2. The cylinder can only be locked when the shift lever is in neutral position. These functions are the same as those of the mechanical interlock and are executed under the same conditions. These functions are the same as those of the mechanical interlock and are executed under the same conditions.

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7 Summary From the first series of tests we can conclude that the hypothesis “the range group shifts too slow” is not correct. In the measurements conducted on the test track there are no signs of this being the case since the range group was always shifted well before shifting of the main gears was started. However an unwanted noise could be heard from the transmission sometimes. To be able to take a closer look to the transmission it was decided that it would be taken out of the vehicle for further testing. In the new test, with the transmission laying on a table, fast gear shifting was done repeatedly. A new problem was discovered: the gearshift lever was occasionally stuck. Several reasons that could cause this lock up were possible and had to be investigated in order to come to a solution. When making fast shifts from the slow to the fast group, a selection movement is made. This means that a new set of gears is chosen. A possible explanation that the shift lever could not be moved forward, is that it is between two gears. The shift finger would then stand between two shift rails, operating both of them at the same time. This makes it impossible to shift into a certain gear, resulting in a shift lever that won’t move any further. To see if this was the reason for the lock up the shift finger was removed and the test repeated. The problem persisted so something else was tried. The following idea was that the lockup was caused by friction. Maybe the forces on the sliding surfaces of the interlock become so large that they prevent the cylinders from sliding. To investigate this the surfaces of the sliding parts were polished and greased. When they were build in again the shift lever still locked up occasionally. Finally the idea arose that the bolt that slides into the shift cylinder to block it, might not get into the groove in the shift cylinder. A visual inspection of the shift cylinder and the bolt this proved to be causing the problems. The best solution that can be realised without radical changes in the design would be to adjust the dimensions of the grove and the bolt. If the groove would be made a bit wider and the bolt a bit sharper, then the bolt can slide into this groove earlier. The bolt and cylinder would not collide again and the shift cylinder would also be locked. A small remark would be that since the gear shift were performed with great force and speed it is not very likely that this problem will occur in a truck. However it is a functionality of the gearbox that can be improved to make the transmission more robust. An alternative system that could eventually replace the mechanical implementation of the interlock system by an electronically controlled system which is able to fulfil the same functions. Besides a possible more reliable operation this system would also bring weight reduction and maybe cost reduction.

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Part 3: Design assignment

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1 Assignment Nowadays measuring how far the friction lining on the synchroniser cone is worn is done by hand. Since the synchroniser cones have a new friction lining which is elastic, this results in very inaccurate measurement that are not reproducible. For example; at the beginning of an endurance test, the synchroniser reserve was measured. After the test the measurement was repeated and compared with the measurement before testing. According to the measurement the reserve increased after hundreds of synchronisations! To give a better understanding of the causes of this problem we will take a look at the actual measuring method and formulate the desired specifications. In the next chapter a new measuring device will be presented.

1.1 Actual method First it must be clear to know what is meant by the synchroniser wear reserve, this is explained with the help of Figure 16. The synchroniser reserve is determined by measuring A (Maß A) and B (Maß B) with respect to the “0-punt” in the figure. The measure which has the smallest value determines the wear reserve. It is obvious that the more worn the cone is the thinner its friction lining, so the smaller the values of measure A and B.

Figure 16: Synchroniser wear reserve

The synchroniser cone is made out of steel which is then covered with a friction lining. This friction lining used to be chrome-molybdenum which was sprayed onto the synchroniser cone, but this has recently been replaced by a new friction lining. This friction lining is maximum 2 millimetres thick. There are two depths that have to be measured too determine the synchroniser reserve. If the wear reserve is too small, the friction lining is too thin and the friction of the friction lining will be decreased so much that the synchronisers in the gearbox are not be able to function properly, resulting in an unsynchronised gearshift that can damage the gearwheels. To measure the wear reserve, the synchroniser sleeve is laid on a table. Then the synchroniser cone is put carefully inside the sliding collar as horizontal as possible. With the measuring device is checked if the synchroniser cone lies horizontal, by measuring the height of the cone at three points that are distributed equally over the cones circumference. A typical value of an acceptable height difference between the maximum and minimum value is 0.05 mm, if the difference is bigger the position of the synchroniser is adjusted. This is done by pushing on the highest position. After this the height at the three measure positions is measured again, this is done till a maximum height difference of 0.05 mm is reached. To come to one value of the reserve, the mean value of the three measured heights is used, so the reserve is expressed in millimetres.

1.2 Demands for a new measuring method 1. The preload of the synchroniser must be equal with each measurement, for example 5 kg. 2. Accuracy must be 0.01 mm. 3. All synchroniser cones must be measurable, without the need to adjust the device.

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2 Design process

2.1 Ingredients for a new measuring device The following points are important to achieve a good accuracy: 1. The synchroniser cone must be placed in the synchroniser sleeve (also called sliding collar) in such a way

that it is horizontal without the need to correct its position. 2. To guarantee that the preload is constant, a constant load will be applied to press the cone into the sleeve. 3. One size fits all, no extra pieces have to be added or subtracted to the device, since this is time consuming. 4. Both the old and the new set of synchromeshes must be able to be measured.

2.2 Placing the cone inside the sleeve

Figure 17: Global lay-out

In this first design the synchroniser ring must be inserted inside the synchroniser sleeve, which lay’s on the table, manually. Then the weight, which should be perpendicular to the table, presses on the synchroniser ring. The vertical cylinder, on which another cylinder can slide up and down, makes sure that the weight is perpendicular to the table. However the play between the cylinders might be a problem because this results in an undesired degree of freedom; the angle of the synchroniser ring is not fixed. It cannot be guaranteed that the weight is perpendicular to the table.

2.3 Centring the cone and sleeve With respect to precision it would be better to put the synchroniser cone directly horizontal in the sleeve. This is important because the friction lining makes it relatively hard to adjust the position of the cone with respect to the synchroniser sleeve. To accomplish this, the synchroniser cone must be fixed to the horizontal weight, however the weight and the cone must be centred in such an application. There are two ways to accomplish this: 1. Make a form closed construction to centre the cone with respect to the weight. 2. Centre the cone using a force closed construction. The advantage of the first method is that it is quite simple in design, however it might be complicated to produce. Another disadvantage is that it requires a different form for each cone, resulting in many parts, which was not permitted, or a complex form. The advantage of the second option is that the form can be quite simple, however centring is more difficult and the centre line can change position. In practice it might be difficult to guarantee that the cone is exactly centred. In the following figures some examples of centring using a force closed construction are shown.

Figure 18: One spring, two fixed points

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The disadvantage of the implementation of the construction in Figure 18 is that since diameters of the sliding collars and cones are not equal; they will not be centred when this construction is applied to both the upper and lower part of the construction. In the next figure this problem is solved. However here sliding collar and cone are only centred when all the springs have the same spring constant, which is not realisable in practise and not very robust.

Figure 19: Centring by spring force

In the following designs will be chosen for a form closed construction as can be seen in Figure 20, because of the draw backs of a force closed design mentioned here before. Using a form closed construction has the disadvantage that it might be more difficult to produce, however it can be made very robust. A springs stiffness can change because of, for example, overloading the spring. Further could it be difficult to make the design flexible to contain different diameters.

2.4 Adjusting the design for flexibility When looking at the sliding collars it can be seen that the outer diameter is the same in the old as in the new synchronisation. A compact way too fit several different sleeves in one place without having too change many parts can be seen in Figure 20.

Figure 20: Lower dye

This can also be done at the top of the construction that will contain the synchroniser come. If the sliding collars are contained from the outside it is best to hold the synchroniser cones from the inside, so they can fit in each other while doing the measurement. Another idea was to make the bottom dye loose so it could be changed if needed. However when doing this an extra play is introduced, making the design more difficult and more inaccurate. As we will see later there are only three different sizes of sliding collars.

2.5 Attaching the cone to the upper dye There is still a problem left, namely fixing the cones to the upper dye. To make this easy, the cones should be attached to the upper dye in such a way they can be removed without a lot of work. Since a cone is made out of iron, using magnets is an obvious possibility too provide lifting force. However there is not much room in the design for magnets. Searching on the internet resulted in a wide offer of small and powerful magnets. A magnet with a diameter of 5 mm and a height of only 2 mm is very interesting because off its small dimensions. According to the distributor one magnet can lift up to 700 gr. Since the largest cone that has too be lifted weighs 800 grams, three of these magnets should suffice. The magnets are made out of Neodym-Eisen-Bor (NdFeB) that is why they provide such a strong lifting force. As mentioned before there will be used three magnets too attach the cone too the upper

30


dye, they will be distributed equally over the upper dye. The magnets will be glued too the upper dye. It is further important that the magnets are not able to directly contact the cone, since this could influence the parallelism of the cone with the upper dye, leading to an inaccurate measurement.

dye, they will be distributed equally over the upper dye. The magnets will be glued too the upper dye. It is further important that the magnets are not able to directly contact the cone, since this could influence the parallelism of the cone with the upper dye, leading to an inaccurate measurement.

2.6 Global design 2.6 Global design Taking al these remarks into account, a design is made. A schematic cross-section view can be seen in Figure 21. Taking al these remarks into account, a design is made. A schematic cross-section view can be seen in Figure 21.

Bottom dye

Upper dye

Sliding cylinder

Figure 21: Cross-section view Figure 21: Cross-section view

The device is circular. The sliding collars can be put in the bottom dye and the cones can be magnetically attached to the upper dye. The vertical cylinder is perpendicular to the bottom dye and the upper dye can slide over the vertical cylinder. The alignment is provided through the sliding cylinder that is bolted to the upper dye. The upper dye can be taken of and put back upside down to measure the other set of synchronisers. In the bottom dye this is not necessary since the outer diameters of the sliding collars of the old and new synchronisation are equal. The measurement instrument can be placed alongside the bottom dye. Room is left open in the upper dye for the instrument to measure the cone directly. In Chapter 4 the final design is shown.

The device is circular. The sliding collars can be put in the bottom dye and the cones can be magnetically attached to the upper dye. The vertical cylinder is perpendicular to the bottom dye and the upper dye can slide over the vertical cylinder. The alignment is provided through the sliding cylinder that is bolted to the upper dye. The upper dye can be taken of and put back upside down to measure the other set of synchronisers. In the bottom dye this is not necessary since the outer diameters of the sliding collars of the old and new synchronisation are equal. The measurement instrument can be placed alongside the bottom dye. Room is left open in the upper dye for the instrument to measure the cone directly. In Chapter 4 the final design is shown.

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3 Dimensions and tolerances 3 Dimensions and tolerances Now the global design is made the dimensions must be determined. This is done using a CAD program called CATIA, it is used to draw a 3D model. With this program it is easy to make 2D drawings of a 3D model using standard views or user defined cross-section views. The dimensions and the tolerances are also visible in these views.

Now the global design is made the dimensions must be determined. This is done using a CAD program called CATIA, it is used to draw a 3D model. With this program it is easy to make 2D drawings of a 3D model using standard views or user defined cross-section views. The dimensions and the tolerances are also visible in these views. Now the dimensions and tolerances must be defined. Especially at the alignment, small tolerances are crucial to achieve good accuracy, however it must be possible to slide up and down without using great force. Therefore the cylinders must be smooth and straight too avoid lock up. The sleeve will be chosen with a relatively large height to reduce the possibility that the cylinder turns over. It is also important that there is a bit of built-in safety in the device to protect it from flaws made by the operator. If for example the upper parts slips out of his hand and falls on the bottom plate, the device should not get damaged. This will not result into severe damage as long as the planes where the synchroniser ring and sleeve are placed upon are not able to touch each other. Since this could damage these planes and make them lose there parallelity which would result in a serious loss of accuracy. Therefore the dimensions of the sleeve, upper and lower dye are be chosen in such a way that this is not possible.

Now the dimensions and tolerances must be defined. Especially at the alignment, small tolerances are crucial to achieve good accuracy, however it must be possible to slide up and down without using great force. Therefore the cylinders must be smooth and straight too avoid lock up. The sleeve will be chosen with a relatively large height to reduce the possibility that the cylinder turns over. It is also important that there is a bit of built-in safety in the device to protect it from flaws made by the operator. If for example the upper parts slips out of his hand and falls on the bottom plate, the device should not get damaged. This will not result into severe damage as long as the planes where the synchroniser ring and sleeve are placed upon are not able to touch each other. Since this could damage these planes and make them lose there parallelity which would result in a serious loss of accuracy. Therefore the dimensions of the sleeve, upper and lower dye are be chosen in such a way that this is not possible. The most important data of the parts that will have to be measured are presented in Table 6. The most important data of the parts that will have to be measured are presented in Table 6. Characteristic Diameter [mm] Characteristic Diameter [mm]

Outer radius (R) [mm] Outer radius (R) [mm] Total Height (H) [mm]Total Height (H) [mm] Side of the sleeve (h) [mm] Side of the sleeve (h) [mm]

∅ 177 99,25 30 6,1 ∅ 180 99,25 30 6,1 ∅ 196 109 30 9,1 ∅ 199 109 30 9,1 ∅ 226 124 48 15,6

Table 6: Dimensions of sliding collars, for symbols see Figure 22

2R

h

H

d

Figure 22: Top and side view of the collar sleeve

And for the synchroniser cones the characteristic dimensions can be found in Table 7. Characteristic Diameter [mm] Inner radius [mm] Height [mm] ∅ 177 76,75 9,9 ∅ 180 76,95 9,8 ∅ 196 86,95 9,9 ∅ 199 87,25 9,8 ∅ 226 100,2 14,6 ∅ 226 100,4 14,5

Table 7: Cone diameters

The information from Table 6 and Table 7 is all we need to determine the dimensions of the upper and bottom dye. Here the tolerances must be chosen small as well since the sleeve and ring otherwise have the room to move relatively to the central axis. Too achieve a high measuring accuracy this movement must be kept as small as possible. However the tolerances of the cone and the sliding collar are relatively large, being between +0,5 mm and –0,2 mm for the cone, and –0,3 mm for the outer diameter of the sliding collar. Compared to the tolerances of the measuring device these tolerances are roughly speaking a factor 10 larger. The entire device will be hardened to make the precisely made surfaces more robust. Another reason to harden the device is because it is necessary to achieve the desired tolerances. The sliding cylinder might have to be polished to achieve the desired accuracy.

3232


Figure 23: Synchroniser cone

With the dimensions as mentioned before, the weight of the upper dye and the sliding cylinder connected to it is approximately 4,1 kg, for calculations see Appendix F: Weight calculation. This is thus the preload with which the cones are pressed into the sleeves. The vertical cylinder will be fitted into the bottom dye by means of a pressing. On top of that they will also be welded together. A detailed views of the device can be found in Appendix G: Drawings and in the next chapter.

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4 Final design In this chapter there are two pictures that show the final design; one cross-section view and a top view of the measuring device. Detail and side views are included in Appendix G: Drawings.

Figure 24: Cross-section

34


Figure 25: Top view

35


5 Error estimation 5 Error estimation In this chapter the accuracy of the designed measuring device will be estimated. In this chapter the accuracy of the designed measuring device will be estimated.

5.1 Error sources 5.1 Error sources 1. Play between the cylinders 1. Play between the cylinders 2. Cylinder is not placed perpendicular 2. Cylinder is not placed perpendicular 3. The planes on which the sliding collar and cone are placed are not parallel 3. The planes on which the sliding collar and cone are placed are not parallel 4. Misalignment of the vertical cylinder and the bottom dye 4. Misalignment of the vertical cylinder and the bottom dye

5.2 Play between the cylinders 5.2 Play between the cylinders There is a maximum play, indicated with p, of 0,021 mm between the sliding and the vertical cylinder. The height of the sliding cylinder, indicated by the letter h, is 70 mm. The largest diameter of the upper dye, indicated with the letter D, is 109 mm and the inner diameter of the sliding cylinder d = 50 mm (without including the tolerance).

There is a maximum play, indicated with p, of 0,021 mm between the sliding and the vertical cylinder. The height of the sliding cylinder, indicated by the letter h, is 70 mm. The largest diameter of the upper dye, indicated with the letter D, is 109 mm and the inner diameter of the sliding cylinder d = 50 mm (without including the tolerance).

α

hs

D

d

zs

Vertical cylinder

Upper dye Sliding cylinder

Figure 26: Loss of precision because of rotation caused by play Figure 26: Loss of precision because of rotation caused by play

The height difference at the furthest point at the edge of the upper dye is indicated by zs. The height difference at the furthest point at the edge of the upper dye is indicated by zs.

shp

=αsin Equation 4

Ddzs

−=αsin Equation 5

Combining Equation 4 and Equation 5 results in Equation 6:

( )s

s hpDdz −= Equation 6

With the aforementioned values of hs and p this results in zs = 0,018 mm.

5.3 Cylinder is not placed perpendicular This occurs at two places; where the vertical cylinder is fitted to the ground plate and at the connection between the sliding cylinder and the upper dye. Figure 27 shows a schematic drawing of this situation. The height of the central cylinder is 175 mm and the cylinder must stand within a shell that is perpendicular to the bottom dye and has a radius that is 0,01 mm larger. This results in Equation 7 and Equation 8:

3636


17501.0tan=β Equation 7

( ) βsinDdzw −= Equation 8

For the flange a similar calculation can be made, the only difference is that the flange has a height of 70 mm zw will be 0,000001 mm in this case.

Figure 27: Skewness

5.4 The planes on which the sliding collar and cone are placed are not parallel The allowed tolerance is 0,005 mm, since two planes are used here, the maximum tolerance zp = 0,01 mm.

5.5 Misalignment of the vertical cylinder and the bottom dye Here all the horizontal displacements originating from manufacturing and diameter tolerances are stated. They will be converted in a vertical displacement. • Bottom dye 0,05 mm Maximum difference: 0,1 mm • Upper dye 0,05 mm • Flange not perpendicular or not bolted perpendicular to upper dye 0,01 mm • Vertical alignment not centred: 0,01 mm • Axial displacement originating from the play in the alignment is not taken into account because it is already

negotiated in paragraph 5.2: Play between the cylinders

β

0,01

Lower dye

Vertical cylinder

Flange

xs

Figure 28: Misalignment

Adding the values leads to a horizontal displacement of xs = 0,12 mm. To go from a horizontal displacement to a vertical displacement we need the cone angle of the synchroniser, being κ = 6,5°. Now the vertical displacement zx is:

κtan⋅= xzx Equation 9

This results in a zx of 0,014 mm.

Sliding collar

κ

zx

Bottom dye

37


5.6 Total tolerance Now we can take the sum of the individual tolerances to find the overall tolerance of the measuring device:

totxpws zzzzz =+++ Equation 10

by using Equation 10. Taking all the error sources into account, an overall tolerance of ztot = 0,042 mm can be achieved. The measurement is done at three different points equally distributed. The measured values are then added and divided by three, resulting in a mean value with an even better tolerance. This can be calculated by using the following equation. This results in a total inaccuracy, after averaging, of ztot,mean = 0,014 mm. This is not as small as the desired specification, however it is much better then the current measuring method. The biggest improvement the measuring device brings is that the results are becoming more reliable and in any case reproducible because the device provides a methodology that everybody uses in the same way.

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6 Recapitulation A new measuring device is designed that will help improve the accuracy with which the synchroniser wear reserve can be determined. Especially reproducibility will be enhanced, mainly because the preload on the synchroniser cone is the same with all measurements. The requirement that both the old and new synchronisation set was measurable without adjusting the device is also satisfied. The upper and lower dye are dimensioned in such a way that all parts fit. The upper dye only has to be place upside down to use the other synchroniser set. The desired accuracy cannot be acquired with this design. This is also because the tolerances of the parts that have to be measured are relatively large. This makes the positioning of the sliding collar and synchroniser cone relatively inaccurate which has its influence on the overall accuracy.

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List of symbols h Side of the sleeve H Total height of the sleeve R Outer radius of the sleeve p Maximum play α Angle β Angle zs Vertical displacement zw Vertical displacement zp Vertical displacement zx Vertical displacement ztot Total vertical displacement xs Horizontal displacement κ Angle φ Angle mh Length x Length hs Height of sliding cylinder d Inner diameter sliding cylinder D Largest outer diameter upper dye Fodd Shift force uneven gears (R,1,3,5,...) Feven Shift force for even gears (2,4,6,...)

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Acknowledgement 1. Synchronisierung von NKW-Getrieben, Diplomarbeit von Ottmar Back 2. Untersuchung der Einflußgrößen von Getriebeschleppmomenten an Nfz-Getrieben, Diplomarbeit von

Michael Merholz 3. Taschenbuch für den Maschinenbau 14. Auflage (1981) Springer Verlag Berlin 4. VDI bericht 1175, “Getriebe in Fahrzeugen” 5. Tabellenbuch Metall ISBN3-8085-1086-2, verlag Europa-Lehrmittel, Nourney, Vollmer GmbH & Co.

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Appendix A: Driver A

Figure 29

Figure 30

42


Figure 31

Figure 32

43


Appendix B: Driver B

Figure 33

Figure 34

44


Figure 35

Figure 36

45


Appendix C: Gear ratio overview

46


Appendix D: Synchromesh components

Figure 37

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Appendix E: Interlock Appendix E: Interlock

1

3

2

Shift cylinder

Figure 38

4848


Appendix F: Weight calculation First the volume of the upper dye cylinder with hole will be calculated:

( ) ( )( ) 3432323 10545,2104010601075 m−−−− ⋅=⋅⋅⋅−⋅⋅π Then the volume of the square protrusions is calculated: ( ) 35,1878725108,82025,133095,7404 mm=⋅⋅+⋅+⋅+⋅

This corresponds with and since there are three 351088,1 m−⋅ 351064,5 m−⋅The sliding cylinder is bolted to he upper dye and can be seen as extra weight, its volume is: t

( ) ( )( ) ( ) ( )( ) 343232332323 1017,2101010501065106010501058 m−−−−−−− ⋅=⋅⋅⋅−⋅⋅+⋅⋅⋅−⋅⋅ ππ

The density of metal is 37800 mkg Multiplying the total volume with the density results in the total weight: ( ) kg11,478001017,21064,510545,2 454 =⋅⋅+⋅+⋅ −−−

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Appendix G: Drawings

Figure 39

Figure 40

50


Figure 41

51


Figure 42

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Documents

Trainingship TPC/HDT Test Engineering · 2006. 1. 23. · Title: Trainingship TPC/HDT Test Engineering Author: A.J.Baeten Subject: Praktikum Keywords: Grating, Range group, Synchromesh