tv_19_2012_2_447_449 Lidhesja Shkupi

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1Introduction

2Aim of the research

3Research

A clutch is a friction mechanism, which is placedbetween the engine and the gear box. It transfer the torquefromdriving toworkingpart.Forefficienttransformation ofthe torque, the quality of the friction pair flywheel-lining-pressureplate has big influence. [8]

Basic reason for the insufficient life of the clutch is the

occurrence of sliding in the process of engagement,disengagement and overload of the clutch. In order toincrease the life of the clutch a big effort has been done toimprove the quality of friction linings, which is needed tofulfill sometechnicalrequirements[3,5].

The wearing of lining depends on the composition ofthefrictionmaterialandits technology ofproduction, clutchfriction elements, clutch construction, the number of theclutch engagements anddisengagementsandsoon.

Testing of linings quality is accomplished by differenttreatments. The linings are tested standalone or in anassembly with the clutch. The testing of the standalonesample does not give realistic results for the lining quality.These are used by manufacturer's linings for the sole

purpose of maintaining the quality of linings; they use theirexperience in the production of linings. The testing of theassembly of clutch and linings can be exploitation andlaboratory. Exploitation testing is expensive and timeconsuming. Thelaboratorytesting ischeapand short.

The aim of the research is to determine the dependenceof the number of cycles on the lining wearing at differenttemperaturesof frictionsurfaces.

determine the dependence of lining wearing of thenumber of cycles (engagement - disengagement), testing is

s

447

S Simeonov. et al.

ISSN 1330-3651

UDC/UDK 620.178.16:629.33-585.13

INFLUENCE OF THE NUMBER OF THE CLUTCH ENGAGEMENTS ON THE WEARING OFFRICTION LININGS OF MOTOR VEHICLE CLUTCHES

Simeon Simeonov, Slavco Cvetkov, Sasko Dimitrov, Zlatko Sovreski

Friction clutches are still dominantly used in road motor vehicles. Beside the fact that the basic concept remains the same, requirements for quality andperformance are becoming stronger and stronger. Further development of the friction linings structure and production technology is crucial for fulfilling therequirements. This paper shows how the research was organized in order to determine the influence of the number of cycles on lining wearing at differenttemperaturesoffrictionsurfaces.

Keywords: frictionclutches, linings,motor vehicles,parameters

Subject review

Tarne spojke se jo uvijek dominantno koriste u cestovnim motornim vozilima. Uz ostaje isti, zahtjevi za kvalitetom i radnimsvojstvima su Daljnji razvoj konstrukcije tarnihobloga i tehnologije proizvodnje od presudne je vanosti za ispunjenje zahtjeva.U radu se pokazujekakojeorganizirano istraivanjeradi utvr utjecajabrojaciklusanatroenjeobloga pri temperaturamatarnihpovrina.

injenicu da osnovni konceptjai i jai.

ivanja razliitim

Kljune rijei: motorna vozila, obloge, parametri, tarne spojke

Pregledni lanak

Utjecaj broja ukljuivanja spojke na troenje tarnih obloga spojki motornih vozila

Utjecaj broja ukljuivanja spojke na troenje tarnih obloga spojki motornih vozila

Tehni ki vjesnik 19, 2(2012) -449, 447

performedon friction linings.There are 2 models of the test benches. One of them

works in conditions of braking, and the other test benchworkswith movingof certain rotarymass.

In the first case the clutch works in conditions ofbraking, providing that the kinetic energy of rotarymass has been spent in the clutch which is a brake (Fig.1).

!

1 2 3 4 5

Figure 1 Test table works in condition of braking(1 - drive engine, 2 - rotary mass, 3 - transmitter,

4 - moving parts of the clutch and 5 - fixed parts of the clutch)

In the second case the clutch is loaded in the followingway: from the state of rest, certain rotary mass is moved,whose inertia momentis equivalent to theinertia momentofthevehicle,whoseclutch is tested(Fig.2).

1 2 3 4 5

Figure 2 The test bench works with certain mass moved(1 - drive engine, 2 - driving parts of the clutch, 3 - working parts of

the clutch, 4 - rotary mass and 5 - brake)


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448

Influence of the number of the clutch engagements on the wearing of friction linings of motor vehicle clutches

Technical Gazette 19, 2(2012), 447-449

! Exceptthese2 typesof test benches, there isa test benchthat very often (Fig.1) inserts another clutch instead ofthe brake. In one of the tests, one works in terms ofmoving of rotary mass, and the other one in terms ofbraking.

Fig. 3 shows the process of the clutch engagement,when the power plant is used as an internal combustion

engine(Fig.3a) andan electricengine(Fig.3b).

S Simeonov. et al.

1,0

2,0

1

2

n

r

r

2

1 r

s s n

angular velocity of the driving part (crankshaft of the

internalcombustion engine), /s angular velocity of the driven part. (Drive shaft of the

gearbox), /s

angular velocity of the driving part (electric engine),/s

angular velocity of the driven part (whenelectric power

is), /s angular velocityafter turning of the clutch, /s

time of sliding, s

time of acceleration of the angular velocity of the drivenpart, s

The period of the clutch engagement is considered, inthe time (the time of sliding) the angular velocity of the

driven part increases, the angular velocity of the driving

part decreases.After the time of sliding passed, the two

parts (driving and driven part) are accelerated with angularvelocity and during they gainangular velocity .

At electric engine driving can be approximatelyconsidered that thedecrease inangular velocity isnegligible

rad

rad

rad

radrad

t

t

t

t

t

a)

1,0

2,0

s

ttstr

1

2

n

tt t=s r

2

n1 1

b)

Figure 3 Process of the clutch engagement, with an internalcombustion engine Process of the clutch engagement,

with an electric engine

a); b)

( = =const) and that the initial angular velocity of the

driven (working) part is very small ( = 0). The increasing

of the angular velocity depends on the angular velocity ofthe driven part, the sliding time ( ), the size of the rotary

mass, theamount of torqueof working part) [1,2]From diagrams (Fig. 3) it can be seen that, when using

electric motor as a power plant, there is a slight derogationof the angular velocity ( = ) and the time of sliding is

equal to the time of the acceleration of the working part ( =

), that in relation to the internal combustion engine vary

( > ). The time of engagement of the clutch is the sum

of the sliding time and the time of the acceleration of theworkingpart.

The work of driving part (engine) is spent onaccelerating of the driven part and the work of slipping,duringthe process ofengagement of theclutch.

The settings are done at the test bench for clutches,which works by moving to rotating mass. According to thepossibilities at the test bench and regime of the worldproducers of the linings and clutches can be determined themode of testing of the friction linings, the liningdimensions

350 1953,5.

[3]:

=107J/cm specificworkingload

= 1600 1/min numberof therevolutionsper minute

= 10,22 kgm inertia momentof therotatingmass.

150 C, 200 C, 250 C temperature of friction surface(pressureplate)

numberof cycles,

The9 pairsof linings are examined,at temperaturesof

150C, 200Cand 250C.

Frictionlinings arerivetedonthedisk andtogetherwiththeclutch aremountedonthetestbench.Friction linings are submitted to 500 cycles with 75 %

contact surface of thetotalsurface of linings.

Dismantling of the friction disc and the clutch and thetestbench.Dismantling of linings anddisc.Measuring the thickness of each lining of 16 places (8places evenly to the outer diameter, 8 places evenly tothe innerdiameter)Determination of theaverage thicknessof thelining.Re-assembling of the linings with hard drive

installationdisk,clutchand thetestbench.Fulfillment of the test with 1000 cycles and thetemperature of = 150 C, dismantling andmeasurementof linings (after linings wear).Fulfillmentof thetest with 2000 cyclesand repetition oftheprocedure.Fulfillmentof thetest with 3000 cyclesand repetition oftheprocedure.Fulfillmentof thetestat thetemperatureof 200C.Fulfillmentof thetestat thetemperatureof 250C.

The process of the test clutch engagement is shown infigure (Fig. 4). Fig. 4a shows the change of the angularvelocity of electric engine, where thetime of engagement ofclutch can be seen and angular velocity decreases. Fig. 4bshows the change of the angular velocity of the workingpart, angular velocity increasesare shown. Fig.4c shows thechange of frictionaltorque.

s n

2

r

1 n

r

s

1,0 n

.

t

t

t

n

J

N

Test mode

Test method:

ewl2

2

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. . .

0

0


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449Tehni ki vjesnik 19, 2(2012), 447-449

[2] Simeonov, S. Influence of thecomponentsof frictionmaterial

linings structure on the performances of friction clutch forheavy motor vehicle, PhDthesis,Skopje 1999.[3] Danev, D.Vehicledesign1, Skopje,2000.[4] Danev, D.Vehicledesign2, Skopje,2001.[5] Todorovi , J. Vehicle test methods and procedures, Belgrade,

1995.[6] Rahnejat, H. Multi-Body Dynamics, London and Bury St

Edmunds,1998.[7] Heisler,H. AdvancedVehicleTechnology,London, 1989[8] Nunney, M. J. Light & Heavy Vehicle Technology, London,

2001.

,

.

Authors' addresses

Doc. SimeonSimeonov Ph.D

Doc. ZlatkoSovreski Ph.D

ass.SakoDimitrov MSc

,

ass.SlavoCvetkov, MSc

,

,

FacultyofMechanical engineeringPartizanska 1 2310Vinica,[email protected]



FacultyofMechanical engineering

Partizanska 1 2310Vinica,[email protected]

,

,

,

,

The results of the examination are shown in Tab. 1 and

Diagram(Fig.5).

S Simeonov. et al. Utjecaj broja ukljuivanja spojke na troenje tarnih obloga spojki motornih vozila

S

n1 (1 mm = 4,4 1/s) nn(1 mm = 4,4 1/s) M(1 mm = 50 N m)

a) b) c)Figure 4 The process of the clutch engagement shot of test bench

Number of cyclesN

1000 2000 3000 40000

0,05

0,1

0,15

0,2

0,25

0,3

W

earmm

/

= 150 C

= 200 C

= 250 C

Figure 5 The results of the examination linings wear

Table 1 Lining wear

Number of cycles

N1000 2000 3000

Temperature

/C

Wear /mm 0,056 0,115 0,179 150

Wear /mm 0,069 0,138 0,202 200

Wear /mm 0,088 0,171 0,260 250

4Analysis and conclusions

5References

From these tests we can draw the followingconclusions:

By increasing the numberof cycles, there is an increaseof theliningwear.Increasing the temperature the lining wear increasestoo.Dependence of the lining wear on the number of cyclesis linear(at different temperatures).This research confirms the hypothesis linear wearingof the linings depends on the cycle of engagement, andthis allowspredicting thelifetimeof thelinings.

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[1] Danev, D.Researchof theworkingloads onthe frictionclutchof thepassengercars, PhDthesis,Belgrade 1978.,

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tv_19_2012_2_447_449 Lidhesja Shkupi