【作者】 冯挽强；

【导师】 程秀生；

【作者基本信息】 吉林大学 ， 车辆工程， 2008， 博士

【摘要】 本文结合“无级变速器样机开发”项目,对湿式离合器动态非线性模型及基于湿式离合器动态非线性模型的无级变速器起步平稳性进行了一定的研究,主要围绕以下几个方面进行:1)对湿式离合器接合过程进行了动力学分析,分析了影响湿式离合器动态接合特性的因素和湿式离合器的摩擦类型,及湿式离合器动态接合过程的挤压、压紧和粗糙接触三个阶段摩擦片传递摩擦力矩能力。2)在分析了湿式离合器接合过程中摩擦片间油膜的动态特性的基础上,通过建立挤压、压紧和粗糙接触三个阶段的数学模型,建立了湿式离合器接合过程的动态非线性模型。3)进行了摩擦片间油膜厚度、粘性转矩、粗糙转矩、离合器接合过程传递转矩和不同工况下离合器接合过程传递转矩的仿真分析,由此得到动态摩擦系数的变化趋势和相应的动态摩擦系数数值,从而为CVT起步仿真与分析提供了有效的仿真参数和方法。4)模拟湿式离合器总成的实际工作情况,进行了湿式离合器接合过程台架试验。湿式离合器接合过程试验结果分析表明了湿式离合器接合过程的动态非线性模型的有效性。5)在湿式离合器动态接合特性研究的基础上,分析了CVT湿式离合器起步过程,基于湿式离合器动态非线性模型,建立了湿式离合器接合过程的动力学模型和整车仿真模型,进行了湿式离合器起步仿真分析。仿真结果表明,基于最优片间压力的起步平稳性明显好于基于线性压力的起步平稳性。论文的研究,对提高湿式离合器的动态接合特性及其在CVT和其它自动变速器中的应用具有一定的理论和实际意义。更多还原

【Abstract】 With the development of automobile industry, people request better automotive performance on power,efficiency,comfortableness and security. The automatic transmission can reduce the driver intensity, pertect engine and power transmission system, improve labor productivity, heighten the car’s efficiency and improve automobile emissions performance and so on. Therefore,the automatic transmission is widely used. As the the key component of power train, the wet clutch’s engagement performance directly effects on automatic transmission working condition, the start stability and the quality of shifts gears.In modern vehicle design process, the technology of computer simulation and performance prediction is an analysis tool which is widely used, it may reduce work time and improvement vehicle performance.The engagement performance of the wet clutch engagement process of CVT directly effects on it’s working condition included the vehicle’s start stability. To carry on the analysis and the simulation on CVT .The paper take a carefully research on the wet clutch’s engagement performance, establishes the the wet clutch’s dynamic non-linear model and .conducts the simulation to it, carry out simulation research on start stability of model CVT as work group’s peoject. The paper is made up seven parts.First chapter outlines the research survey of wet clutch and its analyse, the application situation in automatic transmission and the work principle of CVT.Second chapter analyses the characteristic of wet cluth’s engagement performance and its friction type , the ability of friction disk transmitting torque in three stage of extrusion, compaction and roughly contact ,in wet cluth dynamic engagement process.The analyse is the base of set up the non-linear model of wet clutch dynamic engagement.Third chapter analyses the lubricant film principle of work and the the clutch disc’s supporting capacity in the wet clutch dynamic engagement process, establishes the mathematical model of the extrusion stage, compaction stage and roughly stage , the non-linear model of the wet clutch dynamic engagement process is made up of the 3 stage which thorough expresses the characteristics of wet clutch dynamic engagement. the non-linear model of the wet clutch dynamic engagement process provides basic theory for next simulation analysis.The establishment of the non-linear model of the wet clutch dynamic engagement process, thorough expresses the characteristics of wet clutch dynamic engagement. The analysis to it,will make it looks direct and careful.Fourth chapter analyses the simulation research on vehicles transmission system in the method the significance.According to the non-linear model of the wet clutch dynamic engagement process, carries on the simulations of wet clutch’s friction disk lubricant film thickness, the coherent torque, the rough torque,the wet clutch dynamic engagement process torque and the wet clutch dynamic engagement process torque under different working conditions. Under different working conditions, the two friction disk groups torque’s change tendency is not large, so we can obtains change tendency and the dynamic friction coefficient of friction disk group 1 and the friction disk group 2 .Fourth chapter is important on the the wet clutch dynamic engagement process ,which is be esueful to the start simulation research on CVT.The wet clutch’s working condition is complex in engagement process, it is insufficient in its analyse with the theory modelling and the simulation only.We must carry on the bench test toconfirm the simulation result, which will be advantageous for the next research.Fifth chapter the approximate structure of the wet clutch engagement process test, as well , introduces the test situation of wet clutch engagement process experiment and the test result, carries on the test result analyse The test result analyse indicates that, the simulation result and the judgment on change tendency of dynamic friction coefficient in the fourth chapter is correct, the non-linear model of the wet clutch dynamic engagement process is effective.In working condition of each automobile travel mode, vehicle start is the most complex.Conducting the simulation research on start of CVT by wet clutch, may forecast automobile’s stability in this complex mode, reduce the development cycle of corresponding product and development expense.Sixth chapter analysis the process of CVT start by wet clutch, establishes the dynamics model on engagement process of wet clutch, confirm the optimal pressure of the wet clutch, obtains the start time with the fuzzy method , establishes the entire vehicle simulation model, carries on the simulation analysis of CVT start by wet clutch.The simulation result indicates, start stability based on optimal pressure is better than that based on linear pressure . In the simulation process, the non-linear model of the wet clutch dynamic engagement process and dynamic friction coefficient makes it clear that the wet clutch’s dynamic engagement process , enhances the precision of computation and simulation.Seventh chapter is the summary of full text,which mainly elaborated the article’s prime tasks , the research results, and next research direction.The automatic transmission is used moe and more widely, as its key component, the research on wet clutch could be more and more thorough too. CVT has made graet progresses, the simulation research on will make further efforts in the future.更多还原