Secnd Internatnal Cnference n Mechancs, Materals and Structural Engneerng (ICMMSE 2017) Materal Selectn and Analyss f Ol Flm Pressure fr the Flatng Rng Bearng f Turbcharger Lqang PENG1, 2, a*, Hupng ZHENG2, b, Zhanqun SHI1, c 1 Schl f Mechancal Engneerng, Hebe Unversty f Technlgy, Tanjn Chna 300130 2 Schl f mechancal engneerng, Hebe Unversty f Scence and Technlgy, Shjazhuang, Chna 050018 a pq200600@163.cm, bhpzheng@126.cm, cz_sh@hebut.edu.cn Keywrds: Turbcharger, Flatng rng bearng, Ol flm pressure, Dynamc characterstcs. Abstract. Flatng rng bearng has the characterstcs f smple structure, lw pwer cnsumptn and hgh effcency. It s sutable fr hgh speed and lght lad ccasns. It has been wdely used n hgh speed rtatng machnery such as turb charger, avatn engne and s n. Frstly, the materals f each cmpnent f the turbcharger rtr system are selected. Secndly, parameterzed mdel f turbcharger flatng rng bearng was establshed by the sftware DyRBes-Beperf, when rng rat s cnstant analyss f l flm pressure dstrbutn fr flatng rng bearng were cnducted, and eccentrcty, l flm stffness, dampng varatn wth speed. The calculatn n ths paper prvdes sme reference fr the desgn and analyss f the turbne rtr and the flatng rng bearng. Intrductn Turbcharger s drvng part f autmble engne, It play an mprtant rle fr autmble energy savng, emssn reductn and mprve the pwer. At present, turbcharger cmmnly uses flatng rng bearng as the supprtng parts, ts structure s shwn n Fg. 1, flatng rng bearng has duble l flm supprt. It has the advantages f smple structure, lng servce lfe, gd stablty and s n, s t can be wdely used n hgh speed rtatng machnery. Fg. 1 Structure dagram f flatng rng bearng. S far, a lt f research n flatng rng bearng dynamc characterstcs parameters has been dne at hme and abrad: W. J. Zhang, W. Chen [1] cnsderng flatng rng and shaft neck rtary angle speed, dscussed the nner and uter layers f derved n nnlnear dynamc lad f l flm frce analytcal mdel, and analyzed the dynamc effect mechansm n rng rat and whrl rat f flatng rng structure parameters at the dfferent speed eccentrc mass and vscsty f lubrcatng l, and speed rat matchng system parameters senstve t the degree f varatn. S. Y. Xu, M. Yan and thers [2] cnsderng the effect f thermal effect n the rat f the rng, and wth the Cpyrght 2017, the Authrs. Publshed by Atlants Press. Ths s an pen access artcle under the CC BY-NC lcense (http://creatvecmmns.rg/lcenses/by-nc/4.0/). 128
expermental bass, mdfed calculatn frmula f flatng rng bearng speed rat. H. Zhang, Z. Q. Sh [3] usng fnte dfference methd based n the mass cnservng bundary cndtn (JFO) characterzatn f nner and uter l flm pressure dstrbutn f the Reynlds equatn, derved bth nsde and utsde the l flm bearng capacty, flw rate and njectn n l flm pressure l fllng quantty f expressn dfference, starved lubrcatn state f l flm pressure dstrbutn mdel was bult. Usng MATLAB t carry n the smulatn cmputatn f flatng rng bearng lubrcatn mechansm, analyss the statc lad and supply pressure f the flatng rng and the shaft neck statc equlbrum pstn, bth nsde and utsde the l flm end dscharge and dfferental pressure l fllng quantty, and then dscuss the starved lubrcatn cndtn f Jurnal f statc equlbrum pstn. Bass n the lubrcatng flud thery, cnsderng the thermal effcency t deal wth l flm vscsty, the nner and uter bearng eccentrcty change rules wth the speed were calculated, when speed rat s cnstant, flatng rng bearng nner and uter l flm pressure ware calculated at the dfferent speed f turbcharger rtr, the dynamcs analyss f the flatng rng bearng prvdes an mprtant reference fr research, desgnng f rtr system. Nnlnear Dynamc Mdel f Flatng Rng Bearng Basc Mdel f Dynamc Lubrcatn f Flatng Rng Bearng. Fr flud lubrcatn prblem, the general assumptn f lubrcatng l s ncmpressble, accrdng t the equatns f the Reynlds, based n the thery f shrt bearng mdel and plan bearng Reynlds equatn, ntma and adventta equatn f flatng rng bearng have been dscussed, l flm dynamc equatn f flatng rng bearng s get: Outer l flm equatn f flatng rng: h p h p + = 6µ U h x x z z x 3 3 r Inner l flm equatn f flatng rng: p h h p + = 6µ ( U + U ) h x x z z x 3 3 r j where, h s the l flm thckness, subscrpt ndcates the nner l flm, shws the uter l flm; U s the bearng speed, subscrpt r says flatng rng, j ndcates the Jurnal f the jurnal; P s the l flm pressure, ndcates the uter l flm, says the nner l flm. μ s l flm vscsty, expresses the nner l flm, and s says the uter l flm. The frmula (1) s uter l flm pressure cntrl equatn, whch shws that l flm pressure s nly determned by the flatng rng speed, nner l flm pressure cntrl Eq. (2) shws that nner l flm pressure s cntrlled by the cmbned effect f the jurnal speed and flatng rng speed. Calculatn f Rng Velcty Rat Cnsderng Thermal Effect. Thermal effect s an mprtant factr f the effect t turbcharger flatng rng bearng dynamc characterstcs, the man parameters affected by the system thermal effect nclude flatng rng bearng nner and uter layer l flm vscsty, nsde and utsde gap, and rng velcty rat f flatng rng. The frmula adpted n ths paper s [2]: Ωr 1 Ω = = Ω j µ L D C 1+ µ 3 3 L D C Type: Ω says flatng rng speed, r Ω ndcates the shaft speed, µ j, µ respectvely express the nternal and external l flm vscsty; L, L respectvely ndcate the length f the nternal and external flatng rng supprt; C, C respectvely say nsde and utsde l flm gap; D, D respectvely express flatng rng nsde and utsde dameter. 129 (1) (2) (3)
Materal f the Rtr System The mpeller f the cmpressr s made f alumnum ally, and the materal f the rtr shaft sectn s ally f 40CrN, and the mpeller f turbne s made f the K-13 rn and the gld. The perfrmance parameters f these materals are shwn n Table 1. Table 1. Materal Perfrmance f the Rtr System. 3 Name Elastc mdulus (GPa) Densty (kg/ m ) Pssn rat Cmpressr mpeller 72 2680 0.33 Turbne mpeller 176 8000 0.30 Shaft sectn 200 7820 0.30 Analyss f Example The structural parameters f ne turbcharger flatng rng bearng are shwn n Table 2, the bearng lad s 15N, whch drectn s alng the Y axs. Flatng rng bearng wall thckness s B=2.475mm, usng the frmula (3), rng velcty rat f flatng rng bearng can be calculated t ζ=0.21. Table 2. Parameters f Flatng Rng Bearng. Prject f flatng rng Value (mm) Qualty (kg) 0.006 Length (mm) L=7, L=7.2 Inner and uter dameter (mm) D=7.05, D=12 Inner and uter Clearance (mm) C=0.025, C=0.045 Inner and uter vscsty (Pa s) μ= 0.02, μ=0.027 The dynamc characterstcs f the flatng rng bearng are calculated and analyzed by usng the specal bearng analyss sftware DyRBes-Beperf, and the structural parameters are shwn n Table 2. Eccentrcty varatn f a flatng rng bearng wth the rtatnal speed s shwn n Fg. 2, n the fgure,,, respectvely ndcate rate f uter l flm eccentrc rate, bearng r j jr eccentrc rate and the nner l flm eccentrc. Fg. 3 shws that: the three eccentrc rate values f flatng rng bearng vary wth bearng speed and all values decreases when the speed ncrease; and the eccentrc rate f the nner l flm s mnmum, eccentrc rate value f flatng rng uter l flm s maxmum, and bearng eccentrc rate take secnd place. Fg. 2 Varatn Law f Eccentrctes f Flatng Rng Bearng wth Rtatng Speed. 130
These are centrd mtn lcus f a shaft neck and flatng rng n Fg. 3, t can be seen frm the fgure that axle jurnal center and flatng rng mass center mved t the bearng center wth ncreasng speed, and eccentrctes wll decrease wth ncreasng speed. Fg. 3 Change f the track f the axs and the flatng rng alng wth the rtatnal speed. The l flm pressure f l flm bearng s cmpsed f l flm pressure dstrbutn, therefre, the dynamc characterstcs f the bearng s drectly determned by the pressure f the l flm. These are l flm pressure dstrbutn maps f flatng rng bearng at dfferent speeds n Fg. 4. The fgure shws: when bearng axs speed ncreases t 300 thusands per mnute frm 10 thusands per mnute, the mnmum nner l flm thckness ncreases t 0.0245611mm frm the 0.0149587mm and mnmum uter l flm thckness ncreases t 0.0418767mm frm 0.0106371, nner and uter l flm thckness ncreases wth the ncrease f rtatnal speed; maxmum nner l flm pressure decreases t 330.351kPa frm 589.385kPa, l uter flm pressure decreases t 563.774kPa frm 632.415kPa, nner and uter l flm maxmum value decreases wth speed ncreases. Maxmum l flm pressure changes lttle, when the speed value grw mre than 100 thusands per mnute. (a) (n=10000r/mn) (b) (n=100000r/mn) 131
(c) (n=15000r/mn) (d) (n=200000r/mn) Cnclusns (e) (n=25000r/mn) (f) (n=300000r/mn) Fg. 4 Ol flm pressure dstrbutn f flatng rng bearng at dfferent speeds. In ths paper, the dynamc mdel f lubrcatn f the flatng rng bearng was establshed, and the rng velcty rat calculatn f flatng rng has been analyzed, and the dynamc characterstcs have been calculated: (1) The eccentrctes f the nner and uter l flm f flatng rng bearng decrease wth the ncrease f rtatng speed, and the eccentrcty f nner l flm ( jr ) s less than that f uter l flm ( r ). (2) The maxmum l flm pressure f the nner and uter l flm wll decrease wth the ncrease f the rtatng speed, whle the mnmum l flm thckness ncreases. Acknwledgement The authr wsh thank fr research fundng supprt frm the Natnal Natural Scence Fundatn f Chna (51275150). Reference [1] W. J. Zhang, W. Chen, P. L, R. X. Me, Dynamc Effect f System Parameters fr Flatng Rng Bearng Rng Velcty Rat, J. Schuan Unv. (Engneerng Scence Edtn), 47(3) (2015) 160-166. [2] S. Y. Xu, M. Yan, G. Y. L, The Speed Rat Calculatn f Flatng Rng Bearng cnsderng thermal effect, Veh. Engne, 190(5) (2010) 18-21. [3] H. Zhang, Z. Q. Sh, S. X. Zhang, etc. The Analyss f Flatng Rng Bearng Starved Lubrcatn Characterstcs Thery Based n the Mass Cnservng Bundary Cndtn, J. Chn. Mech. Eng. 50(9) (2014) 100-107. 132
[4] P. Zhu, Study n the Characterstcs and Stablty f Ol Flm n the Desgn f Turbcharger Flatng Rng Bearng, master's degree thess f Chngqng Unversty, 2013, 5. [5] L. Tan, W. J. Wang, Z. J. Peng, Nnlnear effects f unbalance n the rtr-flatng rng bearng system f turbchargers, Mech. Syst. Sgn. Prcess. 34(1/2) (2013) 298-320. 133