Thermal performance of disc brakes using genuine and non-genuine brake pads in Kuwait

Transcription

1 Thermal perfrmance f disc brakes using genuine and nn-genuine brake pads in Kuwait Murad, hmad E.; lnaqi, bdulwahab.; Mullali, Hassan.; lsarraf, Jalal; lawadhi, Khaled; lrashed, bdullah...; Mrad, Mukhtar M.. Department f utmtive and Marine Engineering Technlgy, Cllege f Technlgical Studies PET, Kuwait. bstract Disc brake systems play a significant rle in stpping a vehicle by cnverting its kinetic energy int heat energy which is dissipated thrugh the brake system. The perfrmance f the disc brake rtr is critical especially during high temperatures. In this paper, a study f the thermal perfrmance f vented disc brake rtr was carried ut using genuine and nn-genuine brake pads frm the Kuwaiti market in rder t assess the perfrmance and limitatin f each brake pad. n in-huse brake dynammeter was used t investigate the thermal perfrmance f the disc brake and brake pad sat different pressure lads. The results shwed that the thermal perfrmance f the genuine brake pads was much better than that f the nn-genuine nce, especially at high temperatures (fade regin). Furthermre, the cefficient f frictin fr the genuine brake pads was mre stable than that f the nn-genuine-brake pads. Nmenclature pad Pad area [ m ] pistn Brake pistn area [ m ] C Cnstant value f tested brake pad [----] M B Brake trque [ N. m ] P Pressure n the brake pad area [ Pa ] P Brake line pressure [ Pa ] R 1 Outer brake pad radius [ m ] R Inner brake pad radius [ m ] γ ngle f brake pad sectr [ deg ] μ Cefficient f frictin between brake disc and pad [----] Intrductin The main functin f frictin brake pads is t decelerate a vehicle by cnverting the kinetic energy f the vehicle int heat energy which is dissipated thrugh the brake system material and surrundings. Cmpared t drum brakes, disc brakes have been used widely in vehicles, especially in the frnt wheels. The main reasn fr using disc brake systems in the autmtive industry is that they perfrm better brake efficiency than ther type f brakes. Brake system perfrmance has a direct effect n vehicle safety, and is affected by varius parameters such as design, material and perating cnditins [1, ]. One f the main functins f brake pad is t prvide speed cntrl fr the vehicle [3]. In additin, the mst anticipated feature f the brake pad is prviding a sustainable frictin cefficient at elevated temperatures[4]. Many researchers have investigated the thermal perfrmance f brake pads under different braking cnditins [1, 5, 6], and many have lked at the thermal perfrmance f disc and brake pads using bth experimental and numerical appraches [7-18]. The pads frictin cmpsite material has significant impact n the perfrmance f the brake system and als n health and envirnment issues [5]. There are thusands f frictin material frmulatins available n the market with frictin cefficients that vary frm 0.07 t 0.7. sbests brake pads are avided by law, as asbests dust can cause lung cancer [19, 0]. s a result, natural additives, with the additin f high perfrmance frictin materials, are used in the brake pad industry [1, ]. The selectin f frictin elements and understanding f their thermal and wear behaviur are critical and requires a gd knwledge f the raw materials invlved. The aim f this research is t investigate the thermal perfrmance f genuine and nn-genuine brake pads available in the Kuwaiti market in rder t imprve ur understanding, and t make a cmparisn between the different brake pad materials. n in-huse brake dynammeter was used t carry ut the experimental analysis fr the varius brake pads. data acquisitin system was used t mnitr and cllect the utput results frm the brake dynammeter. Methd f study Disc brakes have been widely used in the autmtive industry because f their varius advantages which make them ne f the best chices fr vehicle brake applicatin. During braking, a brake mment is generated as a result f rubbing the frictin material against the disc brake surface. This frictin causes the car t slw dwn r stp by cnverting its kinetic energy int thermal energy which is dissipated thrugh varius brake system cmpnents. The brake trque prduced by the disc brake is determined fr a single wheel accrding t the fllwing relatin: M B γ 4 3 =. π. P. μ.( R 1 R (1) In equatin (1), it is nticed that the majrity f the parameters ( γ, R 1, R ) are cnstant values which are defined during the design steps based n the desired gal. The 3 ) 5806

2 nrmal pressure (P) n the brake pad area and the cefficient f frictin μ vary accrding t the perating cnditins and als based n the prperties f the materials used in the system. The nrmal brake pressure (P), develped between the brake pad and the disc brake, is initiated frm the brake line pressure ( P ), which can be defined as fllws: psitn P = P pad () Frm equatins () and (1), the cefficient f frictin can be derived as: μ = M B C. P (3) ccrding t equatin (3), the cefficient f frictin can be evaluated if the perating pressure and brake trque are knwn. The cefficient f frictin is ne f the mst imprtant parameters that must be mnitred during brake testing in rder t evaluate the perfrmance f the brake pad used. In this study, the cefficient f frictin was determined fr each pad at different brake pressures and temperatures. The braking cnditins used in this wrk were based n Kuwaiti perating cnditins as the material was purchased frm the Kuwaiti market and meets lcal standard. Experimental set-up The thermal perfrmance f the disc brake using bth genuine and nn-genuine brake pads was carried ut using the inhuse brake dynammeter, the general layut f the brake dynammeter is shwn in Figure 1, which cnsists f the fllwing: 11 kw three phase electric mtr with maximum speed f 1500 rpm. Three belts were used t transmit the rtary mtin frm the electric mtr t the main drive shaft. manual gear bx is used t vary the speed and the trque as required by the users. The gearbx is equipped witha clutch unit t engage and disengage the main shaft frm the electric mtr in rder t simulate different brake cnditins. flywheel is used in the system in rder t prvide the desired inertia fr the braking frce. Varius bearings are fitted in the system t eliminate any fluctuatin and bending in the main shaft and als t supprt the varius cmpnents f the main shaft; flywheel, gear bx, etc. Trque transducers are used t mnitr the trque values thrughut the experiments, which are able t measure trque up t 4000 N.m and maximum speed up t rpm. The brake systems were cnnected t a hydraulic circuit in rder t simulate different braking cnditins. The hydraulic circuit cnsisted f a brake lever, master cylinder and fluid pipes, which cnnect t the caliper t actuated the brake frces as desired. The disc brake temperature was mnitred using sliding thermcuples and the rtary mtin speed was measured using a digital tachmeter (SHIMPO EE-). ll parts and cmpnents were assembled n a heavy frame as shwn in Figure 1. Figure 1: Brake dynammeter layut. Results and discussin s explained earlier, the tests were cnducted n the mst ppular brake pads available in Kuwait and the temperature was mnitred during the tests at varius brake pressures. Genuine and nn-genuine brake pads were used in the test in rder t evaluate the effect f each type n the thermal perfrmance f the disc brake rtr. The brake trque and temperature were mnitred and recrded during the tests fr the different brake pads at different brake pressures. Figure, shws the brake trque values against the disc surface temperature at different brake line pressures fr the genuine brake pads. On the ther hand, the brake trque values are pltted against disc surface temperature at different brake pressures fr nn-genuine brake material in Figure 3. M Brake (N.M) Brake Trque Versus Temperature-Original P= 10 bar P= 0 bar P= 30 bar P= 40 bar Figure : Brake trque versus disc surface temperature at different brake pressures fr the genuine brake pads. 5807

3 M Brake (N.M) P= 10 bar P= 0 bar P= 30 bar P= 40 bar Figure 3: Brake trque versus disc surface temperature at different brake pressures fr the nn-genuine brake pads. It can be seen frm Figure () that the brake trque increases with increasing surface temperature until it reached a maximum value when the surface temperature is between 50 and 350 C fr different brake line pressures. The same behavir is apparent in Figure (3) fr the nn-genuine pads with different magnitudes f brake trque. The maximum brake trque was reached when the surface temperature range is175-5 C. The magnitude f the brake trque fr the nngenuine brake pads is lwer than that fr the genuine brake pads. ls it is nticed that the trque fr the nn-genuine brake pads drps steeply cmpared with that f the genuine brake pads, especially during lwer brake pressures. In Figure (3) it is nted that the drp in brake trque at higher pressure (40 bar) is less than at lwer pressure which might be caused by the difference in material prperties f the nn-genuine brake pads when high pressures were applied. In rder t evaluate the perfrmance f the materials used in the different brake pads, the cefficient f frictin fr the genuine and nn-genuine pads were evaluated at different brake pressures, as shwn in Figures (4) and (5) respectively. It is nticed that the cefficient f frictin changed with the change in perating temperature f the brake disc and pads. The cefficient f frictin increases with increasing surface temperature until it reached a maximum, befre drpping again due t high temperature effect. Figure (4) clearly shws that the cefficient f frictin fr the genuine brake pads drps after 350 C, whilst Figure (5) shws that the cefficient f frictin fr the nn-genuine brake pads drps after the surface temperature reaches arund 00 C. ls it is nticed that the cefficient f frictin fr the genuine brake pads is mre unifrm and stable cmpared t that fr the nn-genuine brake pads at different brake pressures bar 0 bar 30 bar 40 bar Figure 4: Cefficient f frictin versus disc surface temperature at different brake pressures fr the genuine brake pads bar 0 bar 30 bar 40 bar Figure 5: Cefficient f frictin versus disc surface temperature at different brake pressures fr the nn-genuine brake pads. Figure 6 was develped t evaluate the effect f brake pressure n the cefficient f frictin fr the genuine and nngenuine brake pads in accrdance t the perating temperature f the disc brake in Kuwaiti envirnment (140 C t 00 C). It was fund that the cefficient f frictin fr the genuine brake pads increases with increasing brake pressure, whilst with the nn-genuine brake pads it decreased with increasing brake pressure. ls it was fund that the cefficient f frictin fr bth genuine and nn-genuine pads were affected by the increase in the surface temperature. p 5808

4 Pressure (bar) g Original- 140 C Cmmercial- 140 C Original- 160 C Cmmercial- 160 C Original- 180 C Cmmercial- 180 C Original- 00 C Cmmercial- 00 C Figure 6: Cefficient f frictin versus brake pressure fr the genuine and nn-genuine brake pads. Cnclusins The current study made a cmparisn between genuine and nn-genuine brake pads that are available n the Kuwaiti market. The change in temperature and cefficient f frictin at different brake pressures were evaluated as explained in the discussin. It is cncluded frm this analysis that the genuine brake pads are mre stable and can withstand the Kuwaiti perating cnditins withut a majr lss in brake trque and perfrmance, whilst the nn-genuine brake pad material was affected severely by the change in temperature and pressure under Kuwaiti perating cnditins. It was fund that the characteristics f the nn-genuine brake pads drpped with the change in pressure and temperature which culd be caused by different cmpsitin f these pads which made them less resistant t Kuwaiti perating cnditins. ls, it was fund that the change in brake trques fr the varius brake pads were resulted by different cmpsitin and manufacturer. Finally, it can be cncluded frm this study that the genuine brake pads have better perfrmance than the nn-genuine brake pads, which makes them mre suitable fr Kuwaiti cnditins. References [1] Day,.J., Frictin and Frictin Materials. Braking f Rad Vehicle, ed..j. Day, J. Klaps, and C.F. Rss. 010: University f Bradfrd. [] Limpert, R., Brake design and safety. nd ed. 1999, Warrendale, Penn: Sciety f utmtive Engineers. [3] Erikssn, M. and S. Jacbsn, Triblgical surfaces f rganic brake pads. Triblgy Internatinal, (1): p [4] Bhushan, B., Mdern Triblgy Handbk, Tw Vlume Set. 000: CRC Press. [5] Bartn, D.C., Mdelling f materials fr autmtive braking. Internatinal Materials Reviews, (6): p [6] Qi, H.S. and.j. Day, Investigatin f disc/pad interface temperatures in frictin braking. Wear, (5-6): p [7] bbas, S.., N.J. Cubitt, and C.J. Hke, Temperature distributins in disc brakes. Prc. Instn Mech. Engrs, ()(9): p [8] damwicz,. and P. Grzes, nalysis f disc brake temperature distributin during single braking under nn-axisymmetric lad. pplied Thermal Engineering, (6-7): p [9] lnaqi,.., D.C. Bartn, and P.C. Brks, Thermal Perfrmance f Mnlithic and Cated Disc Brakes Using baqus and Matlab Sftware, in 013 SIMULI Cmmunity Cnference013: Vienna, ustria, SIMULI Cmmunity Cnference. [10] lnaqi,.., et al. Thermal Perfrmance f PEO Cated Lightweight Brake Rtrs Cmpared with Grey Cast Irn. in Eurbrake France. [11] min,.m., S.M. Seri, and V.R. Raghavan. Study f the temperature distributin in disc brakes by the methd f rder-f-magnitude analysis in Reginal Cnference n Engineering Mathematics, Mechanics, Manufacturing & rchitecture [1] Belhcine,. and M. Buchetara, Thermal analysis f a slid brake disc. pplied Thermal Engineering, 01. 3: p [13] Chi, Z., Thermal Perfrmance nalysis and Gemetrical Optimizatin f utmtive Brake Rtrs, in Mechanical Engineering008, University f Ontari Institute f Technlgy. [14] El-Sharkawy,.E. Transient One-dimensinal Thermal nalysis f utmtive Cmpnents fr Determinatin f Thermal Prtectin Requirements. in SE Technical paper, [15] Ga, C.H. and X.Z. Lin, Transient temperature field analysis f a brake in a nn-axisymmetric threedimensinal mdel. Jurnal f Materials Prcessing Technlgy, (1-3): p [16] Kim, M.R., et al. Numerical Investigatin f Thermal Behavir in Brake ssembly During the LPINE braking Mde. in SE Technical paper, [17] Pevec, M., et al. NLYSIS OF THERML ND DEFORMTION BEHVIOUR OF THE PSSENGER CR FRONT BRKE DISC. in EurBrake Dresden, Germany. [18] Wawrznek, L. and R.. Bialecki, Temperature in a disk brake, simulatin and experimental verificatin. Internatinal Jurnal f Numerical Methds fr Heat & Fluid Flw, (3-4): p [19] Bledzki,.K. and J. Gassan, Cmpsites reinfrced with cellulse based fibres. Prgress in Plymer Science, (): p [0] Yun, R., P. Filip, and Y. Lu, Perfrmance and evaluatin f ec-friendly brake frictin materials. Triblgy Internatinal, (11): p [1] Matějka, V., et al., Jute fibers and pwderized hazelnut shells as natural fillers in nn-asbests rganic nn-metallic frictin cmpsites. Materials & Design, : p

5 [] Ikpambese, K.K., D.T. Gundu, and L.T. Tuleun, Evaluatin f palm kernel fibers (PKFs) fr prductin f asbests-free autmtive brake pads. Jurnal f King Saud University-Engineering Sciences, (1): p