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.     

无级变速汽车驾驶模拟器的模糊控制器设计

为了设计无级变速汽车自动驾驶模拟器的模糊控制器，建立了简化的无级变速汽车驾驶模拟器模型。通过仿真分析了模糊控制器的隶属函数形状和解模糊算法等对控制器性能的影响，提出了适合于车辆在复杂运行工况下的模糊控制策略，为无级变速汽车传动系统的模糊控制器的设计提供了理论依据。     

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.     

Speed ratio control of a parallel layout double cavity half-toroidal CVT for four-wheel drive

A double cavity half-toroidal CVT has two variators, which gives a hint of a new four-wheel drive without a center differential gear unit by applying each of them to drive front and rear drive shafts independently. Torque re-circulation at cornering or different tire radii between front and rear tire is avoided by compensating the speed ratio of variator. The controller adjusts the attitude angle of power roller of the front variator against the rear by measuring the steering angle at cornering. This paper describes the speed ratio control system of the 4WD-CVT with speed ratio range of 1 : 8.7 and test results of vehicle motion mounted on a 3.2L RV.     

全电调节橡胶带式CVT的试验研究

在分析现有带式CVT调节方式优缺点的基础上,提出了一种采用双电机分别调节主、从动带轮工作半径以实现速比变化的全电调节方式,并以橡胶V型带CVT为应用对象研制了首台全电调节CVT样机.通过台架试验对样机进行测试.得到了其速比与执行电机转角的对应关系以及不同速比下其传递转矩和传递效率随带轮动盘夹紧力的变化规律,从而验证了全电调节无级变速的可行性.     

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。     

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。     

CVT电液系统中电磁阀特性的仿真与试验研究

为了对某样机CVT电液控制系统的特性进行分析,以实现对系统的精确控制,对受控元件(电磁阀)特性进行了详细研究。通过分析电磁阀的工作方式,建立了脉宽调制高速开关阀和比例电磁阀的数学模型,并对其进行了模型仿真和试验验证。结果表明,试验数据与仿真结果基本一致,验证了系统模型的正确性。     

Performance Evaluation of Ball CVT and Comparison with Half Toroidal CVT

This study aims at finding an analytical model of ball continuously variable transmission (B-CVT) behavior and performance, based on the existing model of the half-toroidal traction drive. The geometrical and kinematical aspects of this model have been found. Then, force-moment equilibrium equations have been applied for a B-CVT. The contact behavior has been modeled using the isothermal elastohydrodynamic lubrication (EHL) theory, and spin and relative slip losses have been estimated for this CVT. Finally, the overall efficiencies of the B-CVT have been analyzed and compared with the halftoroidal traction drive. This study results have shown that B-CVT has higher torque efficiency and lower speed efficiency in comparison with half-toroidal CVT. Also, it has shown that the adjustment of axial forces in B-CVT leads to higher efficiency in lower input torques.     

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。     

金属带式无级变速传动的载荷分布及滑移特性研究

借用Shinya Kuwabara和Toru Fujii建立起的CVT功率传递的数学模型，分析了CVT各部件的受力情况，确定了各个分力之间的关系式。在此基础上，分析了CVT的滑移特性，对金属带与金属块之间以及金属块与带轮之间的滑移作了详细的分析，为确定合适的带轮夹持力提供了理论依据。     

电涡流缓速器控制器可靠性研究

本文简要地介绍了电涡流缓速器控制器的基本工作原理,针对电涡流缓速器控制器遇到的普遍性问题提出一些改进建议。     

自动离合无级变速器动力性能试验研究

分析了踏板车自动离合无级变速器(CVT)的测试方法及原理,并以GY6-125型CVT为试件设计了一个试验台架,以测试啮合转速、变速特性等动力性能,并得出了该试件各项力学特性的详细数据和曲线图,较全面地了解了自动变速离合器工作过程中性能特性的状态。该试验平台对自动离合器的调整精准便利,可对CVT进行合理选型或对CVT各部件进行优化设计,以实现CVT与发动机的最佳匹配。     

Development of dry hybrid belt CVT

We have developed a continuously variable transmission (CVT) which has superior transfer efficiency, by thoroughly reducing transfer loss by means of using a dry hybrid belt, using no lubrication composition system around the belt, and using an electric control system of a DC motor.The fuel efficiency and driveability of the prototype vehicle equiped with the CVT were proven equivalent or even superior to a 5 speed manual transmission.     

CVT金属带偏移量计算及其优化

分析了CVT金属带轴向偏移问题,并对其轴向偏移最进行了解析计算.结合某国产乘用车的使用工况,综合考虑CVT不同速比的使用率,利用其道路循环试验的速比记录,提出了以轴向偏移量绝对值平均值最小为目标的金属带对正速比优化方法,并给出了装配过程中的调整方式,较好地解决了金属带轴向偏移问题.     

Active controller design for an electromagnetic energy-regenerative suspension

In this paper, with the parameters acquired from measured and tested data, a three-phase mathematical model is applied to the motor component of the developed electromagnetic suspension actuator. A main/inner-loop structure is used for its active control, and the constraints of the control current and energy flow states of actuator are analyzed by simplifying the inner-loop control system. Two different control modes, i.e., Consumptive Full Active (CFA) and Regenerative Semi Active (RSA) modes, which emphasize vibration control of sprung mass and vibration energy regeneration caused by road roughness, respectively, are proposed. Simulations are carried out using different road conditions, and the results demonstrate that the CFA mode can improve vehicle ride comfort by more than 30 percent, despite battery energy consumption; in RSA mode, the ride comfort can be improved by up to 10 percent with the battery charged by regenerated energy.     

Experimental evaluation of a vehicle steering assist controller using a driving simulator

Human-in-the-loop driving simulator experiments are conducted to evaluate a proposed robust steering assist controller that is designed on the basis of driver uncertainty modelling. A nominal controller (NC) that is designed without consideration of driver model uncertainty is also tested for comparison. Two types of experiments are proposed: a long driving task with nominal configurations and a short driving task with initially large lateral position error. The data are analysed using both time domain and frequency domain metrics. In the time domain, the standard deviation of lateral position error and percentage of road departure are used. In the frequency domain, the stability margins and crossover frequency are used. The driving simulator results indicate that statistically, the designed robust controller shows improvements in the short driving experiments. The improvements in the long driving experiments are less evident because of driver adaptation. The non-robust NC suffers from high gain and should be avoided. The benefits of considering driver model uncertainty in the design of vehicle steering assist controllers are, therefore, justified.     

自密实混凝土配合比及工艺性试验研究

以砂率、胶凝料用量、粉煤灰掺量、水胶比四个因素做正交试验,选择配合比参数,经过正交试验分析,得出同时满足工作性能和力学性能的自密实混凝土配合比。     

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.     

Multi-objective geometrical optimization of full toroidal CVT

The objective of this research is geometrical and kinematical optimization of full-toroidal continuously variable transmission (CVT) in order to achieve high power transmission efficiency and low mass. At first, a dynamic analysis is performed for the system. A computer model is developed to simulate elastohydrodynamic (EHL) contact between disks and roller and consequently, calculate CVT efficiency. The validity of EHL model is investigated by comparing output of this model and experimental data. Geometrical parameters are obtained by means of Particle Swarm Optimization algorithm, while the optimization objective is to maximize CVT efficiency and minimize its mass. The algorithm is run for different values of selected input parameters that are oil temperature, roller tilting angle (speed ratio). Optimization results show that optimized geometrical parameters are approximately constant for various values of input parameters. Also, it is observed that, increasing values of oil temperature and roller tilting angle (in clockwise direction), will decrease power transmission efficiency. An average power transmission efficiency of 86.7% is achieved over a wide range of input parameters, using optimized geometry.