摘要
在石油资源紧缺和环境污染日益严重的背景下，某车企为满足油耗法规要求，急需对某款油耗较高的前置前驱MPV车型进行阻力优化研究。本课题采用理论分析与试验研究相结合的方法，探究目标车型传动系统的阻力水平与分布规律，明确关键传动部件-轮毂轴承对传动系阻力特性的影响比重与优化空间。分析影响轮毂轴承摩擦力矩的相关因素，试验探究各因素对其摩擦力矩的影响规律，并制定优化方案。将优化后的样件装车并进行整车阻力与油耗试验，验证优化措施的有效性。本文的研究工作及成果如下：
（1）分析车辆动力传递过程中传动系的能耗损失，使用逐级拆解的测试方法对目标车和对标车传动系进行阻力分布测试。试验结果表明，目标车的整车空挡平均阻力分别高于两对标车14N与33.4N。传动系中轮毂轴承+轮胎部分的阻力占总传动阻力的比重最大。且与对标车相比，目标车轮毂轴承阻力性能存在较大的优化提升空间。
（2）对轮毂轴承单元所受摩擦力矩进行分析，明确影响其摩擦力矩的相关因素。研究表明轮毂轴承的密封和润滑脂部件对其摩擦力矩有重要影响。对密封型式与结构参数进行优化，优化后的密封件可降低轮毂轴承摩擦力矩12%。对润滑脂配方进行优化，试验表明所得测试油脂最高可降低轮毂轴承摩擦力矩9.9%。
（3）对轮毂轴承的最佳工作游隙进行研究，分析负游隙对轴承摩擦力矩与疲劳寿命的影响。摩擦力矩试验表明，负游隙绝对值越小，轴承摩擦力矩越小，在轴承要求的公差范围内最高可降低摩擦力矩11%。将
负游隙绝对值减小并控制在0.01~0.02mm之间，经疲劳寿命试验验证，该范围的轮毂轴承可满足疲劳及可靠性要求。
（4）制定轮毂轴承的优化方案，并进行样件试制。将原厂轮毂轴承与优化后的样件先后装车，进行整车阻力及整车燃油经济性试验。试验结果表明，优化后的轮毂轴承可使整车传动系阻力矩大幅降低，其中左前轮阻力矩降低6.35%~19.28%，右前轮阻力矩降低18.41%~21.22%；同时整车油耗降低了80mL/100km，降低百分比为1.1%。
关键词：轮毂轴承，燃油经济性，摩擦力矩，疲劳寿命，优化
Abstract
In the context of the shortage of petroleum resources and the increasingly serious environmental pollution,in order to meet the fuel consumption regulations,a car company urgently needs to conduct resistance optimization research on a certain front-drive MPV with high fuel consumption.This paper uses the combination of theoretical analysis and experimental research to explore the resistance level and distribution law of the target vehicle transmission system,and to clarify the influence weight and optimization space of the hub bearing,the key transmission component, on the transmission system resistance characteristics.The factors affecting the friction torque of the hub bearing are analyzed,and t
he influence law of various factors on the friction torque is explored through experiments.An optimization scheme is formulated.The optimized samples were loaded and the vehicle resistance and fuel consumption tests were carried out to verify the effectiveness of the optimization measures.The research work and results of this paper are as follows:
(1)The energy loss of the drive train during the vehicle power transmission process is analyzed.The test method of step-by-step disassembly is used to test the resistance distribution of drive train of the target vehicle and the benchmark vehicle. The test results show that the average resistance of the vehicle's neutral gear is higher than the two pairs of standard vehicles14N and33.4N.The resistance of the hub bearing+tire part of the drive train accounts for the largest proportion of the total transmission resistance.Compared with the benchmark vehicle,there is a large optimization and improvement space for the target wheel hub bearing resistance performance.
(2)The friction torque of the hub bearing unit is analyzed to determine the relevant factors affecting the friction torque.Studies have shown that the seals and grease components of hub bearings have an important influence on their frictional moments.The seal type and structural parameters are optimized,and the optimized seal can reduce the frictional torque of the hub bearing by12%.The grease formulation was optimized and tested to show that the resulting test grease can reduce the frict
ional torque of the hub bearing by9.9%.
(3)The optimal working clearance of the hub bearing is studied,and the
influence of the negative clearance on the bearing friction torque and fatigue life is analyzed.The friction torque test shows that the smaller the absolute value of the negative clearance,the smaller the frictional torque of the bearing.The friction torque can be reduced by up to11%within the tolerances required by the bearing.The absolute value of the negative clearance is reduced and controlled between0.01and 0.02mm.The fatigue life test proves that this range of the hub bearing can meet the fatigue and reliability requirements.
(4)The optimization plan for the hub bearing is formulated and the prototype is prototyped.The original wheel bearing and the optimized sample were loaded successively to carry out the vehicle resistance and the fuel economy test of the whole vehicle.The test results show that the optimized wheel bearing can greatly reduce the resistance torque of the whole vehicle transmission system,in which the left front wheel resistance torque is reduced by6.35%~19.28%,and the right front wheel resistance torque is reduced by18.41%~21.22%.At the same time,the vehicle fuel consumption is reduced.80mL/100km,the percentage reduction is1.1%.
Key words:Wheel bearing,fuel economy,friction torque,fatigue life,optimization
目录
摘要 (Ⅰ)
Abstract (Ⅱ)
第1章绪论 (1)
1.1研究背景 (1)
1.2研究目的与意义 (3)
1.3国内外研究现状 (4)
1.3.1传动系统阻力优化研究 (4)
1.3.2轮毂轴承技术的发展 (6)
汽车轴承1.3.3轮毂轴承研究 (7)
1.4研究内容 (8)
第2章传动系统阻力分布试验研究 (10)
2.1传动系统阻力分布研究 (10)
2.1.1传动系统概述 (10)
2.1.2传动系统功率损失分析 (11)
2.1.3汽车行驶阻力分析 (12)
2.2传动系统阻力分布对标测试 (13)
2.2.1测试方法 (13)
2.2.2试验原理 (14)
2.2.3试验设备及台架 (15)
2.2.4试验工况 (17)
2.2.5试验流程 (17)
2.3阻力试验结果分析 (19)
2.3.1试验实测阻力数据 (19)
2.3.2传动部件阻力 (22)
2.4本章小结 (26)
第3章轮毂轴承单元结构优化研究 (27)
3.1轮毂轴承单元 (27)
3.1.1轮毂轴承结构特点 (27)
3.1.2轴承摩擦力矩分析 (28)
3.2影响轮毂轴承摩擦力矩的因素 (30)
3.2.1密封件对轮毂轴承摩擦力矩的影响 (31)
3.2.2润滑脂对轮毂轴承摩擦力矩的影响 (33)
3.2.3轴承精度对轮毂轴承摩擦力矩的影响 (35)
3.2.4工作游隙对轮毂轴承摩擦力矩的影响 (36)
3.3轮毂轴承摩擦力矩试验研究 (37)
3.3.1轮毂轴承摩擦力矩试验 (37)
3.3.2密封结构优化的试验探究 (39)
3.3.3润滑脂优化的试验探究 (2)
3.4本章小结 (3)
第4章轮毂轴承游隙优化研究 (2)
4.1轮毂轴承游隙的计算 (2)
4.2轮毂轴承游隙影响因素分析 (3)
4.2.1过盈配合对轮毂轴承工作游隙的影响 (3)
4.2.2润滑油膜对工作游隙的影响 (5)
4.2.3其他影响因素 (6)
4.3轴承游隙对摩擦力矩的影响及其优化 (6)
4.4负游隙对轮毂轴承疲劳寿命的影响及验证 (7)
4.4.1轮毂轴承疲劳寿命分析 (8)
4.4.2轮毂轴承疲劳寿命试验 (9)
4.5本章小结 (11)
第5章传动系阻力及整车燃油经济性优化验证 (12)
5.1轮毂轴承优化方案 (12)
5.2传动系统阻力优化效果验证 (12)
5.2.1试验设备 (12)
5.2.2试验方法 (13)
5.2.3试验结果分析 (14)
5.3整车燃油经济性优化验证 (2)
5.3.1试验原理及设备 (2)
5.3.2试验流程 (5)
5.3.3试验结果分析 (5)
5.4本章小结 (2)
第6章总结与展望 (3)