A Study on the Role of TRIZ in DFSS · 2018. 11. 11. · A Study on the Role of TRIZ in DFSS Jong Ho Kim, Ill Soo Kim, Hong Wook Lee and Byung Ok Park Hyundai Motor Company ABSTRACT

INTRODUCTIONAs the circumstances of automotive industry change, it is

expected to find a way to develop creativity in order to solveengineering problems or to create new ideas. There areactivities to develop a new concept in the phase of conceptdevelopment, the second phase of DFSS. The phase ofconcept development which provides the greatest opportunityfor innovation is the place where the most importantdecisions are made. It is broadly believed to be the placewhere 80∼90% of the cost and performance are determined.So creating new ideas in the second phase of DFSS isessential to succeed in DFSS projects. In the phase of conceptdevelopment, there are many ways to create or developconcepts through brainstorming, benchmarking, Pughmethod, and etc. Among the several creativity tools, TRIZprovides effective tools for creativity. It helps engineers toovercome the innovation killers such as psychological inertia,limited knowledge, and contradiction. It also helps to solvethe problems and create new ideas. In addition, TRIZprovides the effective tools which enable engineers to predict

the future technology and get the new ideas from it. Thisstudy shows how TRIZ is used in the second phase of DFSSto create new ideas by improving or modifying the presentconcepts and ideas. With TRIZ, it is possible to develop themore refined concepts than present ones. The conceptproduced by conducting TRIZ is in the initial stage and maynot satisfy the criteria of performance and reliability due tofailure modes. In this case, it is necessary to find the failuremode of the concept which needs to be corrected andimproved. Therefore, conducting FMEA on the concept isneeded to identify potential failures. It is also needed toconduct the optimization process during the phase of designoptimization, in order to fix the failure mode of the conceptand hereby optimize the concept. As a result of optimization,the concept gets to reach the ideal function and becomesrobust against the noise factors. In the last phase, the phase ofdesign verification, the optimized concept is embodied andthen a test is conducted to verify whether the optimizedconcept satisfies the target value of the related companyevaluation criteria. This study presents the role of TRIZ in thesecond phase of DFSS. It also shows how to connect the

2012-01-0068Published 04/16/2012

Copyright © 2012 SAE Internationaldoi:10.4271/2012-01-0068saepcmech.saejournals.org

A Study on the Role of TRIZ in DFSSJong Ho Kim, Ill Soo Kim, Hong Wook Lee and Byung Ok Park

Hyundai Motor Company

ABSTRACTThe Design For Six Sigma (DFSS) process consists of four phases, identification & definition of opportunity, concept

development, design optimization, and design verification. In the phase of concept development, TRIZ (Russian acronymfor Theory of Inventive Problem Solving) is useful for creating new ideas from the present ideas, which includes thetrimming strategy, the antidote strategy, and the picket fence strategy.

In this paper, systems of a vehicle such as Variable Compression Ratio (VCR) engine, windshield wiper blade, andContinuously Variable Valve Actuation (CVVA) of engine, are selected and new concepts for each system are created byapplying the previously mentioned three strategies.

FMEA (Failure Mode and Effects Analysis), the latter part in the phase of concept development in DFSS, is conductedfor newly generated concepts of systems that are mentioned above. As a result of FMEA, it is found that the wind lift ofthe wiper blade can be a serious problem. Therefore, in attempt to fix the wind lift problem of the wiper blade, theoptimization process is applied to it in the phase of design optimization. All the factors, including input, output, controlfactors, and noise factors, which influence the wind lift of the wiper blade, are identified. The activity of optimizationprocess is conducted to obtain the optimized design of wiper blade. In the phase of design verification, the optimizeddesign of the windshield wiper is tested in a real vehicle and it is proved to meet the target value of evaluation criteria forthe wind lift. The conclusion is that TRIZ in the second phase of DFSS makes it possible to create new concepts from thepresent ones, which can be optimized and then later verified to meet the requirements with the follow-up phases of DFSS.

CITATION: Kim, J., Kim, I., Lee, H. and Park, B., "A Study on the Role of TRIZ in DFSS," SAE Int. J. Passeng. Cars -Mech. Syst. 5(1):2012, doi:10.4271/2012-01-0068.

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concept coming from TRIZ tool and the follow-up activitiesto the second phase of DFSS, for example FMEA,optimization process, and verification of results, in order tomake the concept robust (less variation) and efficient (highperformance) in the development of vehicle.

TRIZ ROADMAPTRIZ consists of two-step activities, problem

identification and problem solving connected to conceptcreation. Each step includes several detailed tools. TRIZprocess and the tools for TRIZ are shown in Figure 1. Each ofTRIZ tools has its own characteristics and engineer can applythese tools to their own problem in order to get the solutionsand improve their ideas and designs.

Figure 1. TRIZ Roadmap

The function analysis is a tool for problem identification.It describes functions and their usefulness betweencomponents of system and supersystem, and therefore it canidentify the key problems which need to be solved. Trimmingis a tool which removes certain components of the system anddelegates their functions to one of the components in theremained system. The trimming is useful to create new ideaswith low cost compared to the present concepts.

The contradictions, scientific effects, substance-fieldmodel, ARIZ (Russian acronym of Algorithm for InventiveProblem Solving), and the laws of engineering systemevolution are used for problem solving and idea creation.Altshuller's Matrix, inventive principles, and separationprinciples can be used when an engineering systemencounters the situation with contradictions, for exampleengineering/physical contradictions. An engineeringcontradiction is a situation where one parameter is improvedwhile another parameter is worsened. Altshuller's Matrix is aproblem solving tool and provides certain inventiveprinciples for solving the engineering contradictions. Aphysical contradiction is a situation in which an engineeringsystem demands contradictory values from the sameparameter. A physical contradiction can be solved by using

the separation principles which separate contradictorydemands. When the applicable solutions and technology areavailable in other industries, the scientific effects are veryeffective. The scientific effects are the problem solving toolsbased on identifying existing technologies and utilizing them.When both engineering problems and models of solutions aredescribed as the interaction between substances and fields,substance-field model can be used. If a satisfactory solutioncan't be found by using tools such as contradictions, scientificeffects, and substance-field model, it is recommended to useARIZ. ARIZ transforms an unclear and fuzzy initialengineering situation into a very well defined model of theproblem while it expands the resources to help solving theproblem. When an engineering system has too manyproblems and contradictions and thereby it is hard to create asolution, the laws of engineering system evolution enable tobring new concepts of the next or future generation.

DEVELOPMENT OF CONCEPT INTHE SECOND PHASE OF DFSS

There are strategies which enable to create new ideasfrom the present ones. They also enable to strengthen ourown ideas and thereby prevent others from circumventingthem.

1. Trimming strategy

2. Antidote strategy

3. Picket fence strategy

TRIMMING STRATEGYThe trimming is to eliminate one or several components

of the system while retaining or even improving thefunctionality of the system. The resulting system will be ofhigher value compared to the original system because it willhave lower cost and will be simpler. So the resulting systembecomes the new concept. The sequence of the trimmingstrategy is as follows. First, the function analysis is conductedon the present concept. Based on the function analysis result,certain components of the present system are eliminated andtheir functions are carried on by other components of theremained system to create new concept. To demonstrate theeffectiveness of trimming strategy, Variable CompressionRatio (VCR) engine and a wiper blade of windshield areselected and new ideas are developed on them as examples.

1. Case study on VCR engineThis strategy is applied to the development of VCR

engine to get a new concept compared to the present conceptas shown in Figure 2. If the compression ratio of the enginebecomes large, then the thermal efficiency increases andthereby fuel economy is improved, but the engine powerdecreases due to the knocking. So the engine needs to havehigh compression ratio (high C/R) to get the higher fuel

Kim et al / SAE Int. J. Passeng. Cars - Mech. Syst. / Volume 5, Issue 1(May 2012) 23



economy, while it needs to have low compression ratio (lowC/R) to get the higher engine power.

Figure 2. Present VCR Engine

Figure 3 shows the function analysis on the presentsystem and the trimmed system. The component A, B, C, thecontrol link, and the control pin are trimmed as shown in thepresent system of Figure 3. The function to move the lowerlink is delegated to the cylinder block as shown in thetrimmed system of Figure 3.

Figure 3. Function Analysis and Trimming in VCREngine

As a result of trimming, there is a secondary problem thatthe cylinder block has to move the lower link. This is becauseit is not known about how to move the lower link with thecylinder block. So the inventive principles are used to solvethe secondary problem as shown in Figure 4. The inventiveprinciple no. 14 (curvature; the traveling path for the controlpin is curvilinear inside the control slot. The control pin isconnected to the bottom part of lower link.) is applied to findthe path for the bottom part of lower link. The inventiveprinciple no. 15 (dynamics; the control slot moves up anddown under the condition of variable compression ratio.) isused to get the idea about changing the position of the controlslot and meeting the target value for both low and highcompression ratio. The new idea of the control slot issuggested as shown in Figure 4. By incorporating the controlunit which adjusts the position of the control slot, the conceptof control slot is completed.

Figure 4. Idea for Secondary Problem Solving

2. Case study on a wiper bladeAnother case study for the trimming strategy is a wiper

blade on the windshield. Figure 5 shows the present wiperblade which consists of primary/secondary cover, primary/secondary lever, and yoke, etc.

Figure 5. Present Wiper Blade

Figure 6 shows the function analysis on the presentsystem and the trimmed system. The primary lever of thepresent wiper blade whose function is to move the secondarylever is trimmed and the function to move the secondary leveris delegated to the primary cover.

The new concept is produced as described in the trimmedsystem of Figure 6. The primary cover of the new conceptmoves the secondary lever, while it does not move thesecondary lever in the present system. Figure 7 shows thenew concept of the wiper blade. As a result of trimming, thenew concept reduces the number of components compared tothe present system and thereby reduces the cost of the system.

Kim et al / SAE Int. J. Passeng. Cars - Mech. Syst. / Volume 5, Issue 1(May 2012)24



Figure 6. Function Analysis and Trimming in WiperBlade

Figure 7. Idea of Wiper Blade Using Trimming

ANTIDOTE STRATEGYThe antidote strategy is to strengthen our own idea in

order for other people not to circumvent it (There is anantidote to inventing around, to deter other people frominventing around our own idea.). This strategy can beconducted in the way that our own idea is circumvented byourselves and then the circumvented concept is developed toa more improved concept or a future generation concept. Soother people will not be able to try to develop the conceptrelated to our own idea any more. The antidote strategy isapplied to the concept of control slot in VCR engine, in orderto strengthen the original concept of control slot which comesfrom the application of the trimming strategy as shown inFigure 4. Figure 8 shows the function analysis on the originalconcept of control slot in VCR engine.

Figure 8 also shows that the control pin is trimmed inorder to circumvent the original concept of control slot andthe control slot is connected to the lower link through theupper pin. So the new concept of control slot is produced asshown in Figure 9. The new concept of control slot is a resultfrom strengthening our own original concept of control slotby using the antidote strategy. Therefore, it is difficult forother people to circumvent the concept of control slot in VCRengine.

Figure 8. Trimming in VCR Engine with Control SlotConcept

Figure 9. Idea for Antidote Strategy

PICKET FENCE STRATEGYThe picket fence strategy is used when the present idea is

simple, very basic, and key fundamental, but sometimes out-of-date, and it is very difficult to use it. In the above situation,it is needed to predict how the technology based on thisfundamental idea evolves and then to invent a new idea onincremental innovations about the core technology. The newidea on incremental innovations can become a barrier to theeffective use of the technology by other people. The laws ofengineering system evolution help applying the picket fencestrategy to the new concept development. The laws ofengineering system evolution are statistically provendirections of engineering system development that describesthe natural transitions of engineering systems from one stateto another. They are based on analysis of technology historywhich has the high-level patterns of technology evolution.The laws of engineering system evolution have several sub-laws such as the law of increasing controllability and the lawof decreasing human involvement. So they enable to predictfuture technologies such that many new ideas related to thefuture trend of core technology can be produced. Thisstrategy is applied to the Continuously Variable ValveActuation (CVVA) of a engine which controls the valvetiming. Figure 10 shows the present concept for CVVA.




Figure 10. Present CVVA in Engine

It is not possible to change the valve timing for thepresent system when the valve lift is set. (The valve timing isdependent on the valve lift such that it is not possible tochange the valve timing at fixed valve lift). Thecontrollability is limited in the present concept. According tothe laws of engineering system evolution, as the engineeringsystem evolves, the controllability is increased (law ofincreasing controllability). So it is necessary to invent a newidea with the increased controllability, based on the presentsystem. In order to increase the controllability of the presentCVVA, the inventive principles are used and the new idea isinvented as shown in Figure 11. The secondary cam of thenew concept in Figure 11 is operated in the way that the rollerand the pivot are separated (inventive principle no. 1,segmentation) and the center position of the roller moves bythe actuator (inventive principle no. 15, dynamics).Therefore, the distance between the pivot and the roller of thesecondary cam of the new concept changes and thereby thevalve timing can be controlled independently, regardless ofthe valve lift.

Figure 11. Idea of control of valve Timing

As the mechanism of the new concept which makes thevalve timing independent with the valve lift is invented, thesystem of the new concept gets the different valve timing (αand β) at the fixed valve lift of 5 mm as shown Figure 12when the distance between the pivot and the roller of thesecondary cam is changed to 20 mm and 25 mm.

Figure 12. Mechanism of Changeable Valve Timing

FMEA IN THE SECOND PHASE OFDFSS

The concept which is derived from the activities of TRIZis in the initial stage and may not meet the requirements forthe performance and reliability due to failure mode. In casethat the concept has a possibility of having a failure mode, ithas to be found out the failure mode of the concept byconducting Failure Mode and Effects Analysis (FMEA).FMEA is needed to identify potential failures of the conceptand to find the activities to countermeasure them. The thirdphase (phase of design optimization) and the fourth phase(phase of design verification) of DFSS are also needed to fixthe potential failure mode of the concept or to make theconcept robust. FMEA is conducted on the new concept ofthe wiper blade resulting from the activities of TRIZ becauseit is the initial concept and hereby has a possibility to includethe potential failures. It is found out that the wiper blade hasseveral potential failures. Table 1 represents the FMEAconducted on the wiper blade, showing the failure modessuch as insufficient function to remove water, water sucking,noise & vibration, and wind lift.

Table 1. FMEA on idea of wiper blade




Among the failure modes of the wiper blade, the wind liftcan be a serious problem and occur frequently. Table 1 showsthat the inappropriate shape of the spoiler in the wiper bladecauses the failure mode of wind lift. It is also recommendedto conduct optimization on the shape of spoiler of the wiperblade to remove the failure mode of wind lift and improve it.Therefore, the third and fourth phases of DFSS are conductedon the concept of the wiper blade to optimize the spoiler ofthe wiper blade and to verify the optimization result.

OPTIMIZATION OF DESIGN IN THETHIRD PHASE OF DFSS

The optimization process of DFSS is chosen to improvethe wind lift performance.

PARAMETER DIAGRAMThe graphical representation of control factors, noise

factors, input factors, and output response is shown in Figure13.

Figure 13. Parameter Diagram of Wiper Blade

The control factors and the noise factors which haveeffects on the output response are chosen as shown in Figure14 and 15.

Figure 14. Control Factors of Wiper System

Figure 15. Noise Factors of Wiper System

IDEAL FUNCTIONThe design intent of the wiper blade in the aerodynamic

performance is to remove or reduce the wind lift at highspeed of a vehicle. As the vehicle speed increases, the windlift becomes more serious. It means that at higher vehiclespeed, the wiper blade tends to move upward from thewindshield surface due to the lift force. The lift force of thewiper blade is the output response related with waste ofenergy and it needs to be minimized over a range of vehiclespeed. This relationship between the vehicle speed and liftforce, shown in Figure 16, is defined as the ideal function.Signal-to-noise ratio (S/N ratio) is the index to evaluate therobustness. The robustness indicates the amount of variationdue to noise factors. The slope in the ideal function, β,represents the efficiency of the function. In Figure 16, it isdesired that the wiper blade has less variation (high S/N ratio)and low efficiency (low β) in the ideal function.

Figure 16. Ideal Function to Reduce the Wind Lift ofWiper System

However, low β has a possibility to reduce S/N ratio inFigure 16, meaning that the wiper system has more variation.Therefore, it is needed to switch the output (y) and the input(M) so that the desired wiper system has high β and herebyrepresents high S/N ratio as shown in Figure 17. Figure 17shows the inversion of input (M) axis and output (y) axis. Inthis system, the design intent is to maximize the slope β sothat the lift force is minimized over the range of vehiclespeed. It is also desired that the wiper system has lessvariation in the lift force, higher S/N ratio.




Figure 17. inversion of axes for Ideal Function toReduce the Wind Lift of Wiper System

ORTHOGONAL ARRAY ANDCALCULATION OF S/N RATIO ANDSLOPE

An L18 orthogonal array is selected to set up anexperiment which is conducted through the computersimulation as shown in Table 2.

Table 2. Orthogonal Array

For each of 18 experimental runs, S/N ratio and the slopeβ are calculated as shown in Table 2.

MAKE PERDICTIONS AND CONDUCTCONFIRMATION

After completing 18 experimental runs of orthogonalarray and calculating S/N ratio and the slope β for all thecontrol factors, two-step optimization is conducted and thusthe optimal design is determined. The S/N ratio and the slopeβ for the initial and the optimal design are predicted. Table 3shows that the result of the prediction and the confirmationfor the initial and the optimal design. The predicted β value ofthe optimal design is improved by 9.6% compared to theinitial design. The confirmed β value of the optimal design isimproved by 9.3% compared to the initial design. Bothpredicted results and confirmed results are close to each otheras shown in Table 3. It confirms the experiment.

Table 3. Prediction and Confirmation

VERIFICATION OF DESIGN IN THEFOURTH PHASE OF DFSS

The hardware of the optimal design is built. It isincorporated into a vehicle and tested on the road. Thevehicle test for the verification has limitations in measuringthe lift force of the wiper blade, which is the output responseof the ideal function in the parameter diagram of Figure 13.Instead, the vehicle speed at which the wind lift of the wiperblade starts is measured as the output response in the vehicletest. This is because the higher the vehicle speed at which thewind lift of the wiper blade starts, the better the performanceof the wind lift is. “The larger-the-better” is selected for thecalculation of S/N ratio with which the robustness of thewiper blade is evaluated. The noise factor for the vehicle testis different from that of the computer simulation done in theorthogonal array. This is due to the limitations on the vehicletest. In the test, the vehicle moves in the forward directionunder a noise condition of N1, while the vehicle moves in theopposite direction under a noise condition of N2. Table 4shows that the optimal design gets the gain of 7.3 dB, whichmeans that the variation due to noise factors is reduced by57%, and that it improves the efficiency by 16%. So theoptimal design meets the target value of more than 160 KPHunder both noise condition N1 and N2 as shown in Table 4,while the initial design does not. The optimal design whoseconcept comes from TRIZ becomes robust against noisefactors, improves efficiency, and satisfies the target valuewhich is desired in the real market.

Table 4. Verification in the Vehicle Test

CONCLUSIONSA study on the role of TRIZ in DFSS is conducted. TRIZ

is applied to the development of a concept and thereby theconclusions below are acquired.

1. TRIZ is a useful tool in order to invent a new concept ofnext generation by modifying the present concept or to




strengthen our own present ideas during the conceptdevelopment phase of DFSS.

2. The secondary problems encountered during inventingnew concepts and making them real can be solved with theTRIZ problem solving tools such as inventive principles.

3. The potential failure modes of the initial concept resultingfrom the activities of TRIZ are identified by conductingFMEA. The potential failure modes of initial concept can befixed and optimized through the follow-up phases to conceptdevelopment of DFSS, which results in making conceptrobust against noise factors and improving the efficiency offunction of the concept.

REFERENCES1. Chowdhury, S., “Design for Six Sigma:The Revolutionary Process for

Achieving Extraordinary Profits”, Dearbon Trade Publishing, pp71-163, 2002.

2. Glazier, T.C., “Patent Strategies”, Law & Business Institute, pp 14-41,1997.

3. Ikovenko, S., Kogan, S., 2006, “Patent practices of addressing doctrineof equivalents and Its substitutes with G3:ID/TRIZ”, Proceedings of theTRIZ Future the World Conference, Kortrijk, 9-11 October 2006, ISBN90-77071-05-9, pp. 143-148.

4. Ikovenko, S. 2004 “TRIZ applications for patent strategies”,Proceedings of the TRIZ Future the World Conference, Florence, Italy.

5. Ikovenko, S. 2003 “TRIZ application for IP strategies”, TRIZ Masterthesis, 125 pages, MATRIZ.

6. Lee, Hong-Wook, “Concept Development of a Variable CompressionRatio Engine”, Sixth TRIZ Symposium in Japan, 2010.

7. Kim, Ill-Soo, “New-Type Wiper Blade Optimization Research”,Hyundai-Kia Motors Group Conference, 2009.

8. Fey, V., Rivin, E., “Innovation on Demand”, Cambridge UniversityPress, pp 112-166

CONTACT INFORMATIONJong-Ho KimR&D Six Sigma TeamHyundai Motor Company772-1, Jangduk-Dong, Hwaseong-Si, Gyeonggi-Do, 445-706,South [email protected]




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A Study on the Role of TRIZ in DFSS · 2018. 11. 11. · A Study on the Role of TRIZ in DFSS Jong Ho Kim, Ill Soo Kim, Hong Wook Lee and Byung Ok Park Hyundai Motor Company ABSTRACT