热门搜索:

  • /?6
  • 下载费用:15 金币 ?

Wheel Travel Example Calculation -chassis system.pdf

关?键?词:
WHEEL TRAVEL EXAMPLE CALCULATION CHASSIS SYSTEM
资源描述:
CS-0200 Wheel Travel Example Calculation Originator: Andy Lane / ALANE Page 1 of 6 Date Issued: 11/29/2006 CS-0200 Example Calculation.doc Date Revised: 12/6/2006 Objective Apply the CS-0200 wheel travel requirement through a real-world example calculation Background This example uses a MacPherson Strut Front Suspension with the jounce bumper located on the strut rod and in a cup on the top mount. The top mount is a dual-path design. Procedure For a detailed explanation of the wheel travel calculation procedure, review the CS-0200 requirement at www.requirements.ford.com This standard requires calculation of three wheel travels, which are expressed as the change in Z- position of the wheel center from design position. ? Maximum Nominal Jounce ? Maximum Nominal Rebound ? Maximum Package Usable Jounce Results Maximum Nominal Jounce Travel: To determine the Maximum Nominal Jounce Wheel Travel, calculate the max jounce damper length (P7 to P36) and then convert this to wheel travel. Max Jounce Damper Length D C E A L dj - - + = where A = fully compressed damper length E = jounce bumper 7g compressed height C = upper mount displacement D = lower mount displacement. A strut has no lower mount compliance, so D = 0. Figure 1 – Strut Module CS-0200 Wheel Travel Example Calculation Originator: Andy Lane / ALANE Page 2 of 6 Date Issued: 11/29/2006 CS-0200 Example Calculation.doc Date Revised: 12/6/2006 To find A, refer to the print in Figure 1. Since there is a gap between the jounce striker cap contact point and P7, A consists of two components, A 1(P36 to Striker Cap) and A 2(Striker Contact Point to P7) Per the damper print in Figure 2, A 1= 319.7mm + 15mm (datum to P36) = 334.7mm Figure 2 – Damper Detail Figure 3 - Upper Mount Hardpoint Offset Per the upper mount print in Figure 3, A 2= 16.85mm (distance from striker contact surface to P7) so then A= 334.7 + 16.85 = 351.55mm In this example, assume SU-1109 for Jounce Bumper Durability is not met so the jounce bumper non metal components must be omitted, giving a jounce bumper compressed height E = 0. In a dual path mount, jounce bumper load passes directly into the body structure and does not go through the upper mount rubber isolator. Therefore upper mount compliance C = 0. CS-0200 Wheel Travel Example Calculation Originator: Andy Lane / ALANE Page 3 of 6 Date Issued: 11/29/2006 CS-0200 Example Calculation.doc Date Revised: 12/6/2006 Then Max Jounce Damper Length = - - + = - - + = 0 0 0 55 . 351 D C E A L dj351.55 mm. Wheel travel vs. damper compressed length is then plotted using an ADAMS Ride Motion event with these settings: ? Replace spring with a 0 N/mm rate spring, turn off all jounce bumpers, rebound bumpers and spring aids ? Use at least 800 steps ? Plot damper length (P7 to P36) vs. wheel travel (P9 Z) Figure 4 - Max Nominal Jounce Plot Using the plot in Figure 4, Max Nominal Jounce Wheel Travel at 351.55 mm compressed damper length is 87.9 mm. Package Usable Jounce Travel: To determine Package Usable Jounce Travel, add the jounce bumper compressed height to the Maximum Nominal damper length (P7 to P36) and then convert this to wheel travel. Usable Jounce Damper Length B L L dj du + = where L dj= Max Jounce Damper Length from previous calculation B = jounce bumper 2g (no spring) compressed height The load on the jounce bumper F jis found by dividing the 2g corner load (2 * GAWR) by the strut motion ratio. Determine bumper height at 2g bumper loading from a jounce bumper force- displacement plot. Then N N F j 6877 1 . 1 7565 = = . In the jounce bumper F-D curve, bumper height B at 6877N = 23.7mm. Usable Jounce Damper Length mm mm mm L du 25 . 375 7 . 23 55 . 351 = + = . From damper length vs. wheel travel plot, Package Usable Wheel Travel at 375.25 mm damper length is 65 mm. CS-0200 Wheel Travel Example Calculation Originator: Andy Lane / ALANE Page 4 of 6 Date Issued: 11/29/2006 CS-0200 Example Calculation.doc Date Revised: 12/6/2006 Figure 5 - Package Usable Jounce Plot Maximum Nominal Rebound Travel: To determine Maximum Nominal Rebound Travel, determine the max rebound damper length (P7 to P36) and then convert this to wheel travel. Max Rebound Damper Length J H G F L dr + + + = where F = P7 to P36 @ Rebound Bumper Contact G = Rebound Bumper Displacement H = Upper Mount Displacement J = Lower Mount Displacement. Again, since the lower mount is rigid, J = 0. Referring to the damper print in Figure 2 and Figure 6 below, F = 509mm +15mm (datum to P36) +1.25mm (Rod Shoulder to P7) = 525.25mm Figure 6 - Upper Mount Rod Shoulder Offset The rebound bumper does not meet the SU-1109, so it is omitted. Rebound Bumper Height = 5.6mm per print, so rebound bumper displacement G = 5.6mm. CS-0200 Wheel Travel Example Calculation Originator: Andy Lane / ALANE Page 5 of 6 Date Issued: 11/29/2006 CS-0200 Example Calculation.doc Date Revised: 12/6/2006 Figure 7 - Rebound Bumper Detail The upper mount is a compression style mount. Calculate displacement at 1/3 of assembled height (2/3 mount compression) in rebound. Assembled height is 4.7mm so the expected displacement mm mm H 5 . 3 7 . 4 3 2 = = . Figure 8 - Upper Mount Compression Max Rebound Damper Length mm J H G F L dr 35 . 534 0 5 . 3 6 . 5 25 . 525 = + + + = + + + = . From damper length vs. wheel travel plot, Max Nominal Rebound Wheel Travel at 534.35mm damper length is 100.5 mm. Figure 9 - Max Nominal Rebound Plot CS-0200 Wheel Travel Example Calculation Originator: Andy Lane / ALANE Page 6 of 6 Date Issued: 11/29/2006 CS-0200 Example Calculation.doc Date Revised: 12/6/2006 Max Nominal Jounce Travel with jounce bumper example If the jounce bumper had met SU-1109 for Jounce Bumper Durability, then the jounce bumper could have been used in the Max Nominal Jounce Travel calculation. Using a spreadsheet with the average motion ratio, a 7g (7*7565N) load is applied to the front axle. Max Nominal Jounce Bumper Load = Motion Ratio * (7g Corner Weight – Unsprung Corner Weight) – Spring Load. Excel gives an 18.2 kN bumper load. Per bumper F-d curve, compressed 7g bumper height E is 16.3mm. This then changes the max jounce damper length calculation. Max Jounce Damper Length = - - + = - - + = 0 0 3 . 16 55 . 351 D C E A L dj367.85mm. Using damper length vs. wheel travel plot, Max Nominal 7g Jounce Travel = 72.6mm. To protect for jounce bumper tuning and degradation an optional 5mm design factor is added to the Max Nominal Jounce travel giving a reported travel of 77.6 mm. Conclusions The travels are then published on the 634 chart as shown below: Table 1 - Wheel Travel Chart Travel [mm] Maximum Nominal Jounce Travel 87.9 Maximum Nominal 7g Jounce Travel 77.6 Package Usable Jounce Travel 65.0 Maximum Nominal Rebound Travel 100.5 References For additional information regarding this example or the CS-0200 wheel travel requirement, contact: Steve Allen (SALLEN) Steve Hopson (SHOPSON) Andy Lane (ALANE)
? 汽车智库所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

关于本文
本文标题:Wheel Travel Example Calculation -chassis system.pdf
链接地址:http://www.autoekb.com/p-7632.html
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

copyright@ 2008-2018 mywenku网站版权所有
经营许可证编号:京ICP备12026657号-3?

收起
展开