SUVBOSCH制動系統(tǒng)設計計算書

,,,SUV-BOSCH制動系統(tǒng)設計計算書,,,,,,,,,,,

,,,,,,,,,,,,,,,

1.結(jié)構(gòu)簡述:,,,,,,,,,,,,靜力半徑,滾動半徑,

"SUV-4x4制動系統(tǒng)前采用盤式制動器，后采用浮動盤式制動器結(jié)構(gòu),前制動器為浮動單缸，后制動器為",,,,,,,,,,,265/70R16,348,378,pk

"浮動盤式結(jié)構(gòu),并具有串聯(lián)式雙管路制動總泵的液壓制動驅(qū)動系統(tǒng)（系統(tǒng)配ABS+EBD，后期選裝ESP）。",,,,,,,,,,,255/70R15,330,359,

2.整車參數(shù):,,,軸距L=,2805,,,,,空載,滿載,P265/70R16,348,378,suv

,參數(shù),,,空載,滿載,,Ψ=a/L=,,0.435294118,0.513492063,P265/65R17,350,377,

,質(zhì)心距前軸a(mm),,,1221,1440.345238,,X=Hg/L=,,0.30745098,0.32855615,,,,

,質(zhì)心高hg(mm),,,862.4,921.6,,Z=a/g=(0.1、0.2、0.3……),,,,,,,

,總質(zhì)量Ga(kg),,,1950,2520,,oa=1-Ψ=,,0.564705882,0.486507937,,,,

,前軸負荷G1(kg),,,1101.176471,1226,,oc=Ψ=,,0.435294118,0.513492063,,,,

,前軸質(zhì)量分配%,,,0.56,0.49,1.0b=,Fμ1b=1-Ψ+X=,,0.872156863,0.815064086,,,,

,后軸負荷G2(kg),,,848.8235294,1294,1.0d=,Fμ1d=Ψ-X=,,0.127843137,0.184935914,,,,

,后軸質(zhì)量分配%,,,0.44,0.51,,f=(1-Ψ)/X=,,1.836734694,1.480745184,"(0,f)",,,

3.汽車動軸荷分配計算:,,,,,,,r=Ψ/X=,,1.415816327,1.562874607,"(r,0)",,,

3.1動軸荷計算:,,,,,,,,,,《BOSCH曲線圖》,,,,

"當汽車以減速度jt制動時,由于減速度而產(chǎn)生的慣性力,使軸荷分配相應改變:",,,,,,,,,,,,,,

式中:G1＇制動時前軸負荷G2＇制動時后軸負荷jt/g=φ道路附著系數(shù),,,,,,,,,,,,,,

其中減速度jt為了計算方便，通常取以重力加速度的若干倍。表一是根據(jù)不同的jt/g值計算出,,,,,,,,,,,,,,

汽車空載和滿載時動軸荷分配值：,,,,,,,,,,,,,,

表一,,,,,,,,,,,,,,

jt/g=φ,,0.11,0.15,0.23,0.418454442,0.4,0.55,0.65,0.8,0.63,1,,,

G1',空載,1167.124706,1191.105882,1239.068235,1352.052216,1340.988235,1430.917647,1490.870588,1580.8,1478.627821,1700.705882,,,

(kg),滿載,1317.075765,1350.194225,1416.431144,1572.464167,1557.184599,1681.378824,1764.174973,1888.369198,1747.267479,2053.961497,,,

G2',空載,782.8752941,758.8941176,710.9317647,597.9477837,609.0117647,519.0823529,459.1294118,369.2,471.3721789,249.2941176,,,

(kg),滿載,1202.924235,1169.805775,1103.568856,947.5358334,962.8154011,838.6211765,755.8250267,631.6308021,772.7325205,466.0385027,,,

3.2動載荷分配比：,,,,,,,,,,,,,,

對汽車在不同的減速度jt/g值時前后軸動載荷分配比按下式計算：,,,,,,,,,,,,,,

前軸動軸荷：G1＇/Ga×100%,,,,,,,,,,,,,,

后軸動軸荷：G2＇/Ga×100%,,,,,,,,,,,,,,

表二為汽車制動時前后在不同減速度jt/g值時動軸荷分配比：,,,,,,,,,,,,,,

,表二(見下頁）：,,,,,,,,,,,,,

jt/g=φ,,0.11,0.15,0.23,0.418454442,0.4,0.55,0.65,0.8,0.629579372,1,,,

G1',空載,59.9,61.1,63.5,69.3,68.8,73.4,76.5,81.1,75.8,87.2,,,

,滿載,52.3,53.6,56.2,62.4,61.8,66.7,70.0,74.9,69.3,81.5,,,

G2',空載,40.1,38.9,36.5,30.7,31.2,26.6,23.5,18.9,24.2,12.8,,,

,滿載,47.7,46.4,43.8,37.6,38.2,33.3,30.0,25.1,30.7,18.5,,,

4.汽車制動力的計算:,,,,,,,,,,,,,,

4.1.汽車制動時所需的制動力Pτ(軸制動力),,,,,,,,,,,,,,

"當汽車以減速度jt/g制動時,前后各自所需的制動力為:",,,,,,,,,,,,,,

前軸:Pτ1=G1＇×jt/g×9.8(N),,,,,,,,,,,,,,

后軸:Pτ2=G2＇×jt/g×9.8(N),,,,,,,,,,,,,,

表三為汽車在不同jt/g值時所需的制動力:,,,,,,,,,,,,,,

jt/g=φ,,0.11,0.15,0.23,0.418454442,0.4,0.55,0.65,0.8,0.629579372,1,,,

Pt1',空載,1258.160433,1750.925647,2792.859802,5544.56811,5256.673882,7712.646118,9496.845647,12393.472,9122.953034,16666.91765,,,

(N),滿載,1419.807674,1984.78551,3192.635799,6448.445236,6104.163628,9062.631859,11237.79458,14804.81451,10780.42691,20128.82267,,,

Pt2',空載,843.9395671,1115.574353,1602.440198,2452.096283,2387.326118,2797.853882,2924.654353,2894.528,2908.308763,2443.082353,,,

(N),滿載,1296.752326,1719.61449,2487.444201,3885.705672,3774.236372,4520.168141,4814.60542,4951.985489,4767.665258,4567.177326,,,

4.2制動器實際所產(chǎn)生的制動力及制動力分配比:,,,,,,,,,,,,,,

4.2.1.汽車前軸制動器所產(chǎn)生的制動力Pτ1＇:,,,,,,,,,,,,,,

前軸制動扭矩:,,,,,,,,,,,,,,

,,,,,,,,,,,,,,

,,,,,,5.7E-04,P0(Nm),,,,,,,

,,,,,,,,,,,,,,

,,,,,,,,,,,,,,

,,,,1.5E-03,P0(Nm),0.007573312,,,,,,,,

式中:MT1:單個前輪能發(fā)出的制動扭矩,,,,,,,,,,,,,,

BEF1:前制動器效率因數(shù),,,,,0.76,,,,,,,,,

d1:前制動器分泵直徑(φ)m,,,,,0.0635,,,,,,,,,

Rk1:前輪滾動半徑(m),,,,,0.378,,265/70R16輪胎,,,,,,,

Rr1:前制動器有效半徑(m),,,,,0.119,,,,,,,,,

4.2.2.汽車后軸制動器所能產(chǎn)生的制動力Pτ2＇:,,,,,,,,,,,,,,

后軸制動扭矩:,,,,,,,,,,,,,,

,,,,,,2.5E-04,P0(Nm),,,,,,,

,,,,6.7E-04,P0(Nm),,,,,,,,,

式中:MT2:單個后輪能發(fā)出的制動扭矩,,,,,,,,,,,,,,

BEF2:后制動器效率因數(shù),,,,,0.76,,,,,,,,,

d2:后制動器分泵直徑m,,,,,0.04200,,,,,,,,,

Rk2:后輪滾動半徑m,,,,,0.378,,,,,,,,,

Rr2:后制動器有效半徑(m),,,,,0.1203,,,,,,,,,

4.2.3.前后制動器實際制動力分配比：,,,,,,,,,,,,,,

,,,,0.69,,k=(1-β)/β=,,0.44225199,,,,,,

,,,,,,,,2.261154323,,,,,,

4.3同步附著系數(shù)：,,,,,,,,,,,,,,

,,,,滿載,空載,,,,,,,,,

,,,,0.63,0.418454442,,,,,,,,,

4.4滿載時前后軸附著力矩：（道路附著系數(shù)Φ=0.48時的附著力矩）,,,,,,,,,,,,,,

前軸附著力矩:,,,,,,,,,,,,,,

,,,,,4075,(N.m),,,,,,,,

后軸附著力矩:,,,,,,,,,,,,,,

,,,,,1802,(N.m),,,,,,,,

4.5最大管路壓力:,,,,,,,,,,,,,,

"產(chǎn)生最大管路壓力矩時(Φ=0.8)的管路壓力為最大管路壓力,故當Φ=0.8時,",,,,,,,,,,后輪先抱死,,,,

此時前輪制動所需的油壓小于后輪制動所需油壓:,,,,,,,,,,,,,,

即:,,,,,,滿載時,,,,,,,,

,,,,,,5.7E-04,P0=,5596,（N.m）,,,,,

,,0.000572542,P0=,4075,,,P0=,9.77E+06,(Pa),管路壓力偏大,,,,

,,P0=,7117379.165,(Pa),,,,9774332.614,,,,,,

4.6制動踏板力計算:,,,,,,,,,,,,,,

式中:Pp:制動踏板力,,,,,,,,,,,,,,

Sm:制動總泵活塞面積,,,,,總泵直徑為:d=,,0.0254,m,,,,,,

,Sm=π/4×d2=,,0.000506451,m2,,,,,,,,,,

P0:制動管路壓力,,,,,,,,,,,,,,

I:踏板杠桿比,,,,I=,4,,,,,,,,,

故:,Pp=,0.000126613,P0(N),,,,,,,,,,,

汽車滿載時制動管路油壓P0為(Φ=0.88):,,,,,,,,,,,,,,

,Pτ2=G2＇×jt/g×9.8,,,,,,,,,,,,,

,,0.000669862,P0=,4767.665258,,,,,,,,,,

,,Pp=,901.2,(N),,,,,,,,,,

"因BJ1049制動系統(tǒng)采用真空助力機構(gòu),所以實際踏板力取決于真空助力器的助力因數(shù)K,所以",,,,,,,,,,,,,,

"實際踏板力為PF=PP/K(見表四）,現(xiàn)該車型真空助力器的K=",,,,,,,,7.3,7.3,,,,,

另助力器的最大輸出拐點為。,,,,,4800,N,,,,,,,,

此時助力器推桿的輸入力為,,,,,770,N,,,,,,,,

,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,

表四:,,φ,0.418454442,0.4,0.55,0.65,0.8,0.63,1,,,,,

,,P0(Mpa),5.80,5.63,5.98,7.42,9.77,7.12,13.29,,,,,

,,PP(N),734.4,713.4,757.5574619,939.3822094,1237.554154,901.2,1682.6,,,,,

,,PF(N),73.8,69.9,103.8,128.7,230.1,123.4,675.1,,,,,

從表中得出：踏板力符合GB7258-1997《機動車運行安全技術條件》的規(guī)定和要求（≤500N）。,,,,,,,,,,,,,,

4.7制動距離計算:,,,,,,,,,,,,,,

"當汽車以均勻減速度jt制動時,其理論制動距離為:",,,,,,,1000,,,,,,,

,,,,,,,156,,,,,,,

,式中:Va:汽車制動時的初速度(Km/h),,,,,,,,,,,,,

,jt:制動減速度jt=g·Φ,,,,,,,,,,,,,

,"實際上,在汽車制動時,由踏下踏板到開始產(chǎn)生制動力尚有一段作用時間,取此值為0.2秒,所以實",,,,,,,,,,,,,

際制動距離St必須考慮這一作用時間。,,,,,,,,,,,,,,

,即：,,,,,,,,,,,,,

,,,,,,,按照φ=0.8時的整車制動強度計算（后輪先抱死）,,,,,,,

,,,,,,P0max=,,,（Pa）,,,,,

,所以：,,,,,整車制動力=,,,（N）（前輪實際產(chǎn)生的制動力+后輪所需,,,,,

,,,,,,整車制動強度=,,,,制動力是整車的制動力）,,,,

,,,,,,則jt/g=φ=,,0.72,,,,,,

,計算時取制動初速度,,,80,Km/h,,,0.72,,,,,,

,則：,,,,,,,,,,,,,

,,,39.37,m≥,22m,,不能滿足要求,,,,,,,

,所以，制動距離符合GB7258-1997《機動車運行安全技術條件》的規(guī)定和要求。,,,,,,,,,,,,,

4.8總泵容量及踏板行程的計算：,,,,,,,,,,,,,,

4.8.1前后軸管路所需的排量：,,,,,,,,,,,,,,

4.8.1.1前制動回路所需的排量：,,,,,,,,,,,,,,

其中：,,——前制動分泵截面積,,,,,,,,,,,,

,,——活塞行程,,,1.2,,,,,,,,,

,,——前制動管路膨脹量,,,,,,,,,,,,

,,——前制動軟管的長度L=,,,0.395,m,,,,,,,,

,,——前制動軟管的數(shù)量n=,,,2,,,,,,,,,

則：,,,1090.2,mm3,,,,,,,,,,

,,,8687,mm3,,,,,,,,,,

4.8.1.2后制動回路所需的排量：,,,,,,,,,,,,,,

其中：,,——后制動分泵截面積,,,,,,,,,,,,

,,——活塞行程,,,1.2,,,,,,,,,

,,——后制動管路膨脹量,,,,,,,,,,,,

,,——后制動軟管的長度L=,,,0.477,m,,,,,,,,

,,——后制動軟管的數(shù)量n=,,,2,,,,,,,,,

則：,,,1316.52,mm3,,,,,,,,,,

,,,4640,mm3,,,,,,,,,,

4.8.1.3實際總泵排量：,,,,,,,,,,,,,,

,總泵的行程為：前腔L前=,,,,0.025,m,,102,,,,,,

,,,后腔L后=,,0.017,m,,,,,,,,

,前腔：,,,,,,,失效,,,,,,

,,,,12661.265,mm3≥,8687,mm3,144.6463856,前,,,,,

,后腔：,,,,,,,,,,,,,

,,,,8609.6602,mm3≥,4640,mm3,144.610514,后,,,,,

4.8.1.4排量的匹配結(jié)果：,,,,,,,,,,,,,,

總泵的排量足夠。,,,,,,,,,,,,,,

4.8.2踏板行程Lp的計算:,,,,,,,,,,,,,,

踏板杠桿比:I=,,,,4,,,,,,,,,,

總泵最大空行程:2mm,,,,,,,,,,,,,,

,,,,,113.26,mm≤,150mm,,,,,,,

制動踏板行程符合標準規(guī)定和要求。,,,,,,,,,,,,,,

5.制動器容量的計算,,,,,,,,,,,,,,

用磨擦片的比能量耗散率[每單位襯片（襯塊）磨擦面積的每單位時間耗散的能量]、比磨擦力,,,,,,,,,,,,,,

[每單位襯片（襯塊）磨擦面積的制動器的磨擦力]來衡量制動器的熱容量和磨損容量。計算結(jié)果見,,,,,,,,,,,,,,

表五：,,,,,,,,,,,,,,

,,,,計算值,,推薦值（最大）,,,,,,,,

,,e1（w/mm2）,,6.69,,6.0,,前制動片容量不夠,,,,,,

,,e2（w/mm2）,,5.02,,6.0,,,,,,,,

,,f1（N/mm2）,,0.34,,0.48,,,,,,,,

,,f2（N/mm2）,,0.15,,0.48,,,,,,,,

其中:,,,,,,,,,,,,,,

式中：,,,,,,,,,,,,,,

Vmax——制