EXPERIMENTAL AND ANALYTICAL INVESTIGATION ON ROLLING BEARING IN RADIATOR COOLANT PUMP

7/23/2019 EXPERIMENTAL AND ANALYTICAL INVESTIGATION ON ROLLING BEARING IN RADIATOR COOLANT PUMP

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CHAPTER – 1

INTRODUCTION

From time to time more attention had given for optimum selection of

bearing type and determining the required characteristics for pump applications.

Pump design engineers are often faced with a difficult question: “How can I

choose among thousands of different bearing types for my application?” In order

to design the optimum bearing arrangement for pumps, the following aspects

have to be considered, magnitude and direction of applied loads, available space,

rigidity/misalignments, arrangement of shaft and bearing position, bearing life

expectation, precision, running accuracy, running noise, operating environment,

lubrication, mounting and maintenance and cost efficiency.

As an important component, the radiator coolant pump bearing is widely

used in the auto engine cooling system. Unfortunately, the radiator coolant pump

bearing itself is often subjected to premature failure because of improper

structure design, poor lubrication or sealing, unreasonable allocation of the

applied loads on two element rows of the bearing and so on. At the present time,

there are many researches on auto water pump bearing lubrication, structures and

material performances, but only few on the bearing loads as well as the influence

of the load variations on the bearing life. Load determination and life prediction

calculation of the bearing are the premises of a good bearing design and a

reasonable working condition matching, and yet it is one of difficulties in the

practical application.

1.1 RADIATOR COOLANT PUMP

A radiator coolant pump is a necessity for the forced circulation type of

engine cooling system. The pump is mounted at the front end of the engine and is

driven from the crankshaft by means of a V-belt. The main parts of the coolant





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effectiveness of rolling bearings in modern engineering applications, a firm

understanding of how these bearings perform under varied and often extremely

demanding conditions of operation is necessary.

Rolling bearings are used in a wide range of applications. When selected

and applied properly, they can operate successfully over a long period of time.

Rolling friction is lower than sliding friction; therefore, rolling bearings have

lower friction energy losses as well as reduced wear in comparison to sliding

bearings. When a rolling-element bearing is in operation, the rolling contacts are

subjected to alternating stresses at high frequency that result in metal fatigue. At

high speed, the centrifugal forces of the rolling elements, high temperature (due

to friction-energy losses) and alternating stresses all combine to reduce the

fatigue life of the bearing. The fatigue life of a rolling bearing is a function of the

magnitude of the oscillating stresses at the contact. If the stresses are low, the

fatigue life can be practically unlimited.

Figure 1.2 (a) Ball Bearing (b) Roller Bearing



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1.3. TYPES OF ROLLING BEARING FOR PUMPS

The different types of rolling bearing are provided in the Table 1.1. The

different bearings types have their characteristics and therefore are suitable for

different applications. The following will provide details about some standard

bearing types commonly used in pump applications.

Table 1.1 Types of Rolling Bearing

BALL BEARING

Radial ball bearingSingle row deep groove

Double row deep groove

Angular-contact bearing

Single row angular-contact

Double row angular-contact

Self aligning double row

Split inner ring

Thrust ball bearing ---

ROLLER BEARING

Radial roller bearingsCylindrical roller

Needle roller

Taper roller bearing ---

Spherical roller bearing ---

Thrust roller bearing

Spherical roller

Cylindrical roller

Tapered roller

Needle roller

1.3.1 Cylindrical Roller Bearings

These are suitable for high radial loads and high-speed applications. Due

to separable outer and inner rings, cylindrical roller bearings enable simple

mounting and dismounting.



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The variants with one lipless ring are ideally used as floating bearings.

Single row and double-row cylindrical roller bearings are available.

1.3.2 Angular Contact Ball Bearings

Such bearings are able to accommodate high radial loads and, when

double-row or paired, high thrust loads in both directions. Angular contact ball

bearings are also suitable for high-speed operations.

1.3.3 Spherical Roller Bearings

These bearings can accommodate manufacturing and assembly

misalignments of shaft to housing, including shaft bending and deflections.

Spherical roller bearings are able to carry very high radial loads and certain axial

loads in either direction.

However, this type of bearing is not suitable for very high speeds.

Standard features such as circumferential grooves and lubricating holes in the

outer ring allow easy for lubricating again and again.

1.3.4 Deep Groove Ball Bearings

The simplest yet the most popular bearings, deep groove ball bearings can

accommodate moderate radial and axial loads and are suitable for very high

speed operations. Different variants in seals and greases are available for

different operating conditions.

Most of these standard bearings are available with various special options

– e.g. cages, clearance groups and seals – to accommodate different operating

conditions.





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The dimensions for rolling element bearings have been standardized and

can be purchased as stock items from specialist manufacturers and suppliers. The

selection of a bearing from a manufacturer’s catalogue involves consideration of

the bearing load carrying capacity and the bearing geometry. For a given bearing,

the load carrying capacity is given in terms of the basic dynamic load rating and

the basic static load rating. The various commonly used definitions for rolling

element bearing life specification are outlined.

The basic dynamic load rating C, is the constant radial load which a

bearing can endure for 1x106 revolutions without evidence of the development of

fatigue in any of the bearing components. The life of a ball bearing, L, is the

number of revolutions (or hours at some constant speed), which the bearing runs

before the development of fatigue in any of the bearing components.

Fatigue occurs over a large number of cycles of loading. For a bearing,

this would mean a large number of revolutions. Fatigue is a statistical

phenomenon with considerable spread of the actual life of a group of bearings of

a given design. The rated life is the standard means of reporting the results of

many tests of bearings. It represents the life that 90% of the bearings wouldachieve successfully at a rated load. The rated life is referred to as the L 10 life at

the rated load. The rated life, L10, of a group of apparently identical bearings is

defined as the number of revolutions (or hours at some constant speed) that 90%

of the group of bearings will complete before the first evidence of fatigue

develops.

If in Equation (1.1), P2 = C and the corresponding life L2 = 1x106, then the

life of a bearing L, with basic dynamic load rating C with a load P, is given by

Equation 1.2,









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1.6. ADVANTAGES OF ROLLING BEARING

They operate with much less friction torque than hydrodynamic

bearings and therefore considerably less power loss and friction heat

generation.

Bearing deflection is less sensitive to load fluctuation.

Combinations of radial and thrust loads can be supported

simultaneously.

Individual designs yield excellent performance over a wide load-speed

range.

Starting friction torque is only slightly greater than moving friction

torque.

They require only small quantities of lubricant for satisfactory

operation and have the potential for operation with a self-contained,

life-long supply of' lubricant.





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Qi An et all., (2012) had done their research for Load Calculation and

Life Prediction for Auto Water Pump. They have taken the water pump

bearing with one roller row (WR)-type auto water pump bearing as a research

sample, an analytical calculation method is developed to improve the accuracy

and efficiency of the current calculations for the bearing loads and life in

engineering application. The bearing load and life calculation results are

compared with those calculated by the traditional method in which the deflection

of the bearing spindle and the roller tilt are ignored. The life decrease in the auto

water pump bearing is significant due to the deflection of the bearing spindle and

it is recommended to give more attention to this deflection for the high quality of

the bearing design and calculation.

Li Zhengmei et all., (2011) examined the Influences of Eccentric

Unbalances on Loads and Life of Auto Water Pump Bearing. The life of

auto water-pump bearing is closely related to its loads which are affected by the

eccentric unbalances of rotational components in the structure system of the

bearing. However, since the bearing structure in auto water-pump is complicated,

the exact load calculations and the life prediction for this kind of bearing are

difficult. In this paper, theWR3258152 auto water-pump bearing is investigated.

The load and life calculation models for the bearing are developed with

considering the eccentric unbalances of the cooling fan and the driving wheel.

The influences of the fan and the wheel unbalances on the loads and life of the

bearing are studied. The calculation and analysis results show that the radial

loads on rolling element rows of the auto water-pump bearing fluctuate

significantly under the actions of the fan and the wheel unbalances and the

bearing life reduces regularly with the eccentric unbalances changing.

Zhang Yongqi et all., (2012) dealt with the Analysis of Stress and

Strain of the Rolling Bearing by FEA Method. Taper roller bearings are

important part of gear reducers, and their work property affects behaviour of the





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within a short period, due to cavities created on the bearing raceway.

Recommendation towards enhancement of bearing life is also suggested.

Necdet Demirhan et all., (2008) analyzed on the Stress and

Displacement Distributions on Cylindrical Roller Bearing Rings Using FEM.

Stress and displacement distributions on inner and outer rings of cylindrical roller

bearings are investigated using the finite element (FE) method. FE models are

solved by considering the interactions of steel shaft, inner ring, rollers, outer ring,

and outer cage using ANSYS. The mesh convergence rates of FE models are

investigated and the optimum number of elements is selected in the models. The

load distributions on rollers are determined. The radial, tangential, and von Mises

stresses are plotted along the inner and outer faces of the inner and outer rings.

R. Sehgal et all., (1999) had made their research on Reliability

Evaluation and Selection of Rolling Element Bearings. A procedure based on

graph theory and matrix approach has been developed for the reliability

evaluation and selection of a rolling element bearing for an application. The

reliability of the bearing is evaluated considering reliability of its elements and

their connections. This is modelled in terms of Reliability Graph of a Rolling

Element Bearing. This graph is represented by an equivalent matrix called

Rolling Element Bearing Reliability Permanent Matrix to obtain a matrix

function-Reliability Permanent Function. This function is the characteristic of

reliability of the rolling element bearing for the application. Reliability Index

( RI) of the bearing is also defined. It is a numerical measure of the bearing

reliability and is obtained by substituting reliability value of the bearing elements

and their connections in the matrix function. The paper also suggests how to

assess these reliability values to obtain the index. The proposed procedure is

useful for designers and practicing engineers for selection of an optimum bearing

for a given application.



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CHAPTER – 3

RADIATOR COOLANT PUMP BEARING

3.1 BASIC DESIGNS

In the case of coolant pump bearings, they are designed and machined to

meet the specifications and conditions required for automotive water pumps,

which are basically set to comply with customer’s requirements. Coolant pump

bearings are non-separable sealed bearings, and they can be divided into two

types depending on the kinds their rolling elements, ball/ball type and ball/roller

type. Because the load capacity of ball-roller type coolant pump bearings is a lot

higher than that of ball-ball type, they are suitable to be used when they have to

support fan couplings, or when they have to transmit high belt loads, or off-set

loads. Experienced pump designers can usually avoid problems due to bearing

overload by a combination of empirical techniques and where necessary

experimental work also been done.

A radiator coolant pump bearing is a ready-to-fit bearing unit. It

comprises a shaft that is supported by means of several rows of rolling elements

in a through hardened outer ring. Under heavier loads, water pump bearings of

the roller/ball design are used. The function can be significantly improved in the

case of this design too by a combination of a row of rollers with a three or four

point contact bearing. These bearings do not have an inner ring but instead have

raceways directly machined into the shaft. As a result, there is more space

available for the rolling elements, giving a higher load carrying capacity than in

solutions with conventional single bearings. In water pump bearings, rows ofballs and rollers can be economically combined with each other. This gives a

broad range of load carrying capacity values.



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Figure 3.1 Radiator Coolant Pump – Existing Model

Figure 3.2 Coolant Pump Bearing – Existing Model



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The use of a common outer ring for two or more rows of rolling elements

prevents misalignment defects, eliminating the risk of undesirable distortion of

the bearings. In water pump bearings, the ends of the shaft normally extend

beyond the outer ring on both sides. The length and diameter of these extended

sections can be matched to the specific application. The ready-to-fit bearing unit

is predominantly used in coolant pumps for road vehicles.

These bearings are not only used in coolant pumps, however, and are

therefore also described as integrated shaft bearings. Due to the characteristics

stated, they have a wide range of possible applications, for example in:

Fans

Tension pulleys

Vane pumps

Angle grinders.





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4.1.4 Arrangement of Shaft and Bearing Position

The arrangement of the shafts (horizontal, vertical or inclined), the shaft

and housing fits based on applied loads, positional arrangements of fixed and

floating bearings, and adjustments or preloading necessary for the bearing are a

few factors to consider.

4.1.5 Bearing Life Expectation

This is an important factor in selecting the optimal bearing types and sizes

in a given application. Customers’ requirements, cost efficiency and experience

from existing applications are just a few benchmarks.

4.1.6 Precision, Running Accuracy, Running Noise

For some applications, high precision and low noise levels are required. In

some cases, a low starting torque is essential.

4.1.7 Operating Environment

Factors such as operating temperature and characteristics of the pumping

media (abrasiveness or corrosiveness, viscosity, presence of solids, etc.) are

crucial for bearing functions. Special lubricants, cages and seals are available for

various operating environments.

4.1.8 Lubrication, Mounting and Maintenance

These factors should be considered for the entire service life of thebearings. For example, if bearings in the machines must be mounted and

dismounted regularly for inspections, separable bearing types such as cylindrical

roller bearings could be advantageous.



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4.1.9 Cost Efficiency

In general, standard bearings are more economical and readily available

due to mass production. Standard bearings with special features (such as special

grease/seals/cages, etc.) are more costly. Special bearings developed for

particular applications entail higher development and production costs, but

provide tailor-made solutions to meet the specific requirements.

4.2 DESIGNING OF COOLANT PUMP BEARING

Since, we are going to design the bearing for a coolant pump which is to

be used in a heavy vehicle. Here, we consider a single row ball and roller type

bearing. Because the load capacity of ball-roller type water pump bearings is a

lot higher than that of ball-ball type, they are suitable to be used when they have

to support fan couplings.

In Figure 4.1, the detailed input drawing for the coolant pump bearing is

given. The tolerances, bearing clearances, cages & seal dimensions and fits are

clearly mentioned.

In Figure 4.2, the input drawing for the pump bearing sleeve is provided in

detail. And in Figure 4.3, the detailed drawing of the integral bearing shaft is

given.





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Figure 4.2 Input Drawing for Bearing Sleeve



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Figure 4.3 Input Drawing for Bearing Shaft



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The bearing is designed with the help of input drawings in the CREO 2.0

version software. The various parts of bearing like sleeve, bearing shaft, rollers,

balls, cages for rollers and balls are drawn separately and assembled. The

exploded view of coolant pump bearing is shown in the Figure 4.4.

Figure 4.4 Coolant Pump Bearing Assembly – Exploded View



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4.3 DESIGNING OF COOLANT PUMP

The ball / roller type bearing is assembled with the coolant pump bearing

by removing the existing taper roller bearing. From Figure 4.5, the exploded

view of the coolant pump is shown.

Figure 4.5 Radiator Coolant Pump Assembly – Exploded View



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The detailed cross sectional view of the coolant pump bearing is shown

the Figure 4.6.

Figure 4.6 Coolant Pump Bearing Assembly – Sectional View



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The cross sectional view of the coolant pump is shown in the Figure 4.7 in

a detailed manner.

Figure 4.7 Radiator Coolant Pump Assembly – Sectional View





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comparable to the standard cast type PA 6 G, but more expensive. PA 66 has

good mechanical strength, high impact strength, good damping characteristics

and good resistance to wear. Here, we take the Young’s modulus as 2000 MPa,

Poisson’s ratio (Nu) = 0.4.

4.4.3 Nitrile Butadiene Rubber (NBR) Material

Nitrile butadiene rubber (NBR) is a family of unsaturated copolymers of 2

- propenenitrile and various butadiene monomers (1, 2 - butadiene and 1, 3 -

butadiene). Although its physical and chemical properties vary depending on the

polymer’s composition of nitrile, this form of synthetic rubber is unusual in being

generally resistant to oil, fuel, and other chemicals (the more nitrile within the

polymer, the higher the resistance to oils but the lower the flexibility of the

material). It is used in the automotive and aeronautical industry to make fuel and

oil handling hoses, seals, and grommets, since ordinary rubbers cannot be used.

Here, we take the Young’s modulus as 20 MPa, Poisson’s ratio (Nu) = 0.49.



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CHAPTER – 5

ANALYSIS OF BEARING

5.1 ASSUMPTIONS FOR ANALYSIS

The solid components are meshed with tetrahedral elements.

The material properties are considered to be linear.

Contact pairs are established at regions where ever it is necessary.

Bolt, nut & washers are not considered for the analysis.

Only structural loading is considered (i.e., thermal loads are ignored)

Pre-loads are ignored.

Shaft and coupling are considered as integral components.

Couplings are rigidly connected using Rigid Elements.

5.2 MESHED MODEL OF BEARING

SOLID185 is used for 3-D modeling of solid structures. It is defined by

eight nodes having three degrees of freedom at each node: translations in the

nodal x, y, and z directions. The element has plasticity, hyper elasticity, stressstiffening, creep, large deflection, and large strain capabilities.

Figure 5.1 SOLID 185 Homogeneous Structural Solid Geometry



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It also has mixed formulation capability for simulating deformations of

nearly incompressible elastoplastic materials, and fully incompressible hyper

elastic materials.

TARGE170 is used to represent various 3-D "target" surfaces for the

associated contact elements CONTA 174 and. CONTA 175. The contact

elements themselves overlay the solid, shell, or line elements describing the

boundary of a deformable body and are potentially in contact with the target

surface, defined by TARGE170. This target surface is discretized by a set of

target segment elements (TARGE170) and is paired with its associated contact

surface via a shared real constant set. You can impose any translational or

rotational displacement, temperature, voltage, and magnetic potential on the

target segment element. You can also impose forces and moments on target

elements.

Figure 5.2 TARGET 170 Geometry



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CONTA174 is used to represent contact and sliding between 3-D "target"

surfaces (TARGE 170) and a deformable surface, defined by this element. The

element is applicable to 3-D structural and coupled field contact analyses. The

element has the same geometric characteristics as the solid or shell element face

with which it is connected. (Contact occurs when the element surface penetrates

one of the target segment elements (TARGE170) on a specified target surface.

Coulomb friction, shear stress friction, and user-defined friction with the

USERFRIC subroutine are allowed. The element also allows separation of

bonded contact to simulate interface delamination.

Figure 5.3 CONTACT 174 Geometry



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5.2.1 Contact details

Figure 5.4 Contact Details between Ball and Inner Shaft



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Figure 5.5 Contact Details between Ball and Outer Ring



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Figure 5.6 Contact Details between Roller and Inner Shaft





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Figure 5.8 Contact Details between Ball and Cage

Figure 5.9 Contact Details between Roller and Cage



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5.2.2 Boundary Conditions

Figure 5.10 Boundary Conditions





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Figure 5.12 Loading Details – Applied









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Figure 6.6 Von Mises Stress Observed in Balls





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Figure 6.8 Von Mises Stress Observed in Outer Ring





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CHAPTER – 7

CONCLUSION

In the first phase of this project, the review of literature on the rolling

bearing, radiator coolant pump, ready to fit type of radiator coolant pump bearing

and the importance of various load acting on the coolant pump bearing have been

done. Also the general considerations in the selection and designing of a bearing

are studied. The radiator coolant pump bearing model have been designed using

CREO 2.0 software according to the inputs provided from the industry

Further in the final phase, the designed model of the radiator coolant

pump bearing has been analyzed using the ANSYS software under static loading

conditions. From the analysis results for the given loading conditions, the

allowable stress is within the limit of the material equivalent stress. Thus the

design is safe.





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EXPERIMENTAL AND ANALYTICAL INVESTIGATION ON ROLLING BEARING IN RADIATOR COOLANT PUMP