Simulation Approach to the Effect of the Ratio Changing Speed of a Metal V-Belt CVT on the Vehicle Response

In regard to the belt and pulley system of a metal V-belt CVT, the characteristics of the ratio changing speed is obtained by experiments. It is summarized in a practical and simple experimental equation. By using this equation a simulation model is developed to analyze the response of a vehicle with a metal V-belt CVT to a rapid pulley ratio change. The simulation results are in reasonable agreements with experimental results.     

Study on transmitting mechanisms for CVT using a dry hybrid V-belt:: numerical simulation of transmitting forces and pulley thrusts at steady and transitional states

An advanced numerical model is proposed to analyze the power transmitting mechanisms for CVT (Continuously Variable Transmissions) using a dry hybrid V-belt. The model consists of linear springs representing the rigidities of blocks, rubber and cord, and interface elements which identify slippage between a pulley and blocks. By using the present model, forces acting on the belt were calculated not only at steady states but also during transitional states where the speed ratio is shifted. Calculated results well coincide with experimental ones. The behavior of blocks in a pulley groove and the relation between pulley thrusts and the properties of shifting the speed ratio are revealed.     

金属带式无级变速传动系统动态特性的理论与试验分析

本文建立了无级变速传动系统的双质量模型，从理论和试验两方面研究了金属带式无级变速传动系统的动态特性。     

Experimental investigation on the efficiency of the pulley-drive CVT

Because of their outstanding advantages over other transmissions, rubber V-belt pulley drive CVTs have been extensively used in low-power vehicles, such as scooters and snowmobiles. A rubber V-belt CVT installed on a snowmobile is used here to research transmission efficiency. The power loss of CVTs, including torque loss and speed loss, is studied based on an analysis of the transmission mechanism of CVTs. Experiments on CVT efficiency are conducted on a specific CVT test bench, on which the values of torque, speed, and displacement, etc., are measured. Results show that the variation trend of the efficiency is close to the operating conditions of CVTs and optimal structural parameters are given that can serve as a beneficial references for designing and tuning CVTs.     

Performance optimization of CVT for two-wheeled vehicles

Continuously Variable Transmission (CVT) is one of the most promising automotive transmission technologies because of its continuously variable gear ratio and reduced shift shock. CVT is different from Manual Transmission and Automatic Transmission, and it is possible to operate the power source in its high efficiency region with CVT in the drive train. Several types of CVT exist that can be categorized based on the mechanism of power transmission, such as the belt pulley, traction drive, and hydrostatic types. This paper investigates the belt pulley CVT, which consists of a thrust actuator, driver pulley, belt, driven pulley, and preload spring of the output shaft. A complete CVT is constructed, and based on that a simulation program that analyzes the static performance of a CVT is implemented in Matlab/Simulink. From these simulation results, methods for improving the efficiency of the CVT are discussed. The coefficient of the torque capacity factor is proposed as affecting the matching between a power source and a CVT, and methods for improving the matching effect are also investigated.     

金属带式无级变速器速比控制的试验研究

基于力-位置控制方案开发了金属带式无级变速器的控制测试系统：在无级变速器的控制系统中，考虑到速比控制阀的饱和非线性特性和无级变速系统的复杂非线性特性，设计了基于速比反馈的速比模糊控制器：试验结果表明，所设计的液压控制系统是可行和实用的。     

Durability improvement of automotive V-belt pulley

Improving the durability of an automotive V-belt pulley, which is commonly used in an automotive powertrain to transfer power to other parts, is discussed. Fatigue life of the original V-belt pulley is predicted based on damage analysis by finite element analysis (FEA). Stress history of the pulley during operation was found by performing consecutive static analyses on the pulley as the pulley rotates. Assembly load (due to the tightening of the bolts) and operation load were considered to describe the actual load conditions in a durability test. The contact condition from the belt was calculated and applied to the surface of the pulley. Static analyses at 36 different positions of the pulley, every ten degrees of rotation, were performed to determine the stress history of the pulley during operation. Using stress history data calculated from FE analysis, damage over one rotation of the pulley was calculated and fatigue life, in number of rotations to failure, was estimated. An improvement to the durability of the pulley was investigated by modifying the design of the pulley using FE analysis results. Durability tests for the pulleys used in the analysis were carried out to verify the analytical results. Comparison between analysis and experimental results showed that analytical results correlated with the experimental results closely.     

金属带式无级变速器电—液控制系统的研究

本文分析了金属带式无级变速器的控制原理和控制方法，设计了用于研究无级变速器匹配规律的试验系统，通过对几种典型工况的性能试验测试的结果表明，所设计的电－液控制系统能够满足无级变速器的控制要求。     

金属带式无级变速器电液控制系统的试验研究

通过对金属带式无级变速液压控制系统功能进行分析，把该系统分为夹紧力控制和速比控制系统。设计了金属带式无级变速器电—液控制系统，对控制阀特性进行了研究，为夹紧力控制系统和速比控制系统分别设计了控制器。最后对所设计的CVT控制系统进行了实车道路试验，取得了较好的效果。     

金属带式无级变速器带轮变形分析

基于为某国产金属带式无级变速器建立的从动带轮三维模型,利用有限元方法,分析了轴向力和速比对带轮变形的影响,并据此拟合出带轮最大变形量和最大变形位置分布的数学公式,再利用文献中现有的试验数据,验证了有限元分析的有效性.结果表明,速比是影响最大变形量位置的主要因素,而轴向力和速比同时影响变形量的大小.     

Experimental study of an electro-mechanical CVT ratio controller

This paper introduces an electro-mechanical, dual acting pulley, continuously variable transmission (EMDAPCVT) and presents its real time ratio controller using a proportional-derivative-plus-conditional-integral (PDPCI) controller. The ratio controller system is developed based on primary (input) and secondary (output) pulley position controllers. Each position controller has two PID parameters, releasing and clamping, which are determined experimentally using a relay feedback method. A PC-based ratio controller system is implemented using Matlab/Simulink® software and a Keithley DAS-1602 data acquisition system card. The experimental results show that the PDPCI controller system can control the CVT ratio adequately.     

机电控制CVT电控电动执行机构参数设计方法（双语出版）

为了使机电控制无级变速器（CVT）能够可靠地传递转矩，快速地调节速比，结合某车型的结构性能参数，对机电控制CVT电控电动执行机构的设计方法进行研究。首先，对机电控制CVT电控电动执行机构的结构和工作原理进行分析，说明电控电动执行机构对CVT速比和从动带轮夹紧力的调节方法，从运动学和动力学的角度研究从金属带式无级变速器的传动机理，获得速比与主动带轮可动盘位移的关系以及保证主、从动带轮可靠传递转矩所需要的夹紧力；然后，根据整车的结构性能参数，明确汽车对机电控制CVT的功能需求和性能要求，以电控电动执行机构中直流电动机的负载转矩最小为目标，设计确定各碟形弹簧的参数和组合形式，在此基础上确定电控电动执行机构中电动机械传动系统的结构性能参数；最后，为验证所设计电控电动执行机构参数的正确性，利用所建立的机电控制CVT传动系统模型在ECE工况下对电控电动执行机构的性能进行仿真分析。结果表明：相对传统CVT液压执行机构，在ECE工况下机电控制CVT电控电动执行机构消耗的能量减少52.2%，同时设计的电控电动执行机构在ECE工况下能够实现实际夹紧力和速比对目标值的良好跟随。     

金属带式CVT速比控制的仿真与试验研究

针对装备金属带式无级变速器(CVT)的整车,建立了无级变速传动系统数学模型.以无级变速汽车动力性和经济性相协调为目标,设计了Fuzzy-PI复合速比控制器.采用Fuzzy-PD控制策略和Fuzzy-PI复合控制策略对汽车起动工况进行了仿真分析,对装备金属带式CVT的某轿车进行了起动工况的模拟试验.结果表明,Fuzzy-PI复合控制策略优于Fuzzy-PD控制策略,速比的试验结果与理论数据一致,说明所建模型合理.     

CVT ratio control with consideration of CVT system loss

A modified CVT ratio map is proposed to obtain the improved fuel economy for a metal belt CVT. Since the CVT system loss, which occupies most of the drivetrain loss, depends on the engine speed, input torque, primary and secondary actuator pressure, a modified CVT ratio map is produced to realize the highest engine-CVT overall efficiency through the consideration of CVT system loss. The modified CVT ratio map is constructed with respect to the demanded vehicle power and present vehicle speed based on the steady state CVT system loss. Using the modified CVT ratio map, performance simulations are carried out using the dynamic models of the CVT powertrain. The simulation results indicate that the modified CVT ratio control provides improved engine-CVT overall system efficiency, and improves the fuel economy of the federal urban driving schedule by 4.9 percent.     

Mechanism of metal pushing belt

This paper investigates the torque transmitting mechanism of a CVT metal pushing type belt by theoretically analyzing working forces on steel bands and blocks. Measuring these working forces, the drive model presented in this paper is shown to be appropriate. Applying this analysis, the relation between belt slip limit and pulley clamping force is derived with enough accuracy for practical use.     

金属带式无级变速器电控系统设计方法的研究

介绍了金属带式无级变速器电控系统硬件构成和软件设计方法。对电控系统中速比与带轮夹紧力的控制进行了具体设计。在台架试验中，根据输入信号模拟汽车整个工作循环过程，对无级变速器控制系统进行了测试。试验表明，该电控系统能够根据输入信号判断行驶工况，并根据汽车当前行驶状态及驾驶员的意图控制执行机构，实现离合器的接合或分离。     

金属带带环疲劳试验研究

带环是金属带中的核心部件,其主要失效形式是疲劳破坏。本试验用动态电阻应变仪测量带环应变,建立应力和测量应变之间的方程,确定进行带环疲劳试验的应力水平;通过疲劳试验,确定带环的疲劳极限,采用参考文献3、4中介绍的数据处理方法处理疲劳试验数据,得到了带环的P-S-N曲线,为金属带的可靠性设计提供了重要依据。     

CVT液压系统功率的匹配分析与仿真

以CVT液压系统为研究对象，建立了压力、流量和功率的仿真模型，并对车辆起步、加速、制动等典型工况和ECE、EUDC循环工况进行了仿真，计算表明采用定量泵供油的CVT液压系统存在较大的功率损失，提出了提高电动液压泵和双联液压泵供油系统效率的新方案，为系统的节能控制奠定了基础。     

Model-Based Integrated Control of Engine and CVT to Minimize Fuel Use

In this study, a model-based integrated control method for engines and continuous variable transmissions (CVTs) is developed. CVT refers to a type of transmission which allows an engine to be operated independently with respect to the vehicle speed, with the engine torque and CVT gear ratio controlled in an integrated manner. In the proposed integrated control scheme, engine operating points which minimize the rate of instantaneous fuel consumption are calculated, and the engine target torque and target gear ratio are determined in an integrated manner based on the results of the calculations. Unlike the previous map-based control method, the method introduced in this study does not require an engine torque map or a CVT ratio map for tuning, and the engine torque and CVT ratio are controlled to minimize the amount of fuel used while satisfying the level of acceleration demand from the driver. The control scheme is based on the powertrain model, and the CVT response lag and transmission loss are also considered in the integrated control processes. The algorithm is simulated with various driving cycles, with the simulation results showing that the fuel economy performance of the vehicle system is improved with the newly suggested engine-CVT integrated control algorithm.     

CVT轿车发动机建模及PID速比控制器设计

针对装备金属带式无级变速器轿车的发动机建立了其转矩模型和目标转速调节特性曲线。对无级变速器速比的取值范围进行了计算,并按照质量集中法简化了传动系的模型。设计了简单实用的PID速比控制器,并在simulink环境下对CVT整车模型起步、急加速和上坡工况进行了仿真分析。结果表明,实际速比对目标速比有很好的跟随效果。