Flow visualization and measurement in the stator of a torque converter

A new experimental apparatus to visualize and measure the flow in the stator of a torque converter was proposed. A one-sided coaxial shaft constructed with an input shaft and an output shaft provides an open space inside the stator shaft for measurement. Through the window on the stator shaft, the flow in the stator can be directly observed.By visualizing the flow with an oil-film method and tuft method, separated regions near the blade surface and flow patterns in the blade passage were observed. Furthermore, using a laser doppler velocimeter, velocity vectors and turbulence intensities were measured in the inlet, outlet and the separated flow in the blade passage of the stator.     

装载机变速装置故障树分析方法

应用故障树分析方法对轮胎式装载机的主要部件--液力机械变速箱进行了分析,根据该部件的结构以及零部件失效与系统之间的逻辑关系,绘制了该部件的故障树,并通过结构函数表示了零部件状态对系统状态的影响.实践证明,故障树所表示的关系与实际使用中发生故障的情况是一致的.     

Development of the Inner Spherical CVT for a motorcycle

An Inner Spherical CVT (ISCVT) transfers engine power by utilizing the traction force of the lubricant fluid film on the contact point between concave and convex spherical rolling bodies. Since the concave and the convex contact surfaces of the ISCVT are exactly spherical parts, they have a large circular (not elliptic) contact area, and the ISCVT mechanism has a larger torque capacity, less spin loss, and better stability than other traction drive mechanisms. The IVT (Infinitely Variable Transmission) performances also can easily be embodied in the ISCVT. In this work, we developed a prototype of the ISCVT for a motorcycle with a 125cc single cylinder engine having a maximum torque of 13.73 Nm at 8,000 rpm. The design parameters were determined, and the transmission performances were evaluated by optimal design procedure. The transmission efficiency, the life time, the maximum severe stresses on each part of the ISCVT, and the work needed for varying speed ratio were theoretically investigated, and the efficiency performances were experimentally measured. The manufactured prototype was installed in an actual motorcycle, which was fixed on the test-bench equipped with a dynamometer. The parasitic loss of the prototype and the cross-sectional road load performance were tested. The power efficiency of the simulated prototype was between 87∼92%, and the life span was more than 50,000 hours. The tested overall power efficiency was around 70∼92% under frequent driving conditions, which is an impressive performance in a motorcycle transmission despite the small difference from the simulation.     

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 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.     

液力变矩器滑摩离合器控制压力计算方法

自动变速器中的滑摩离合器滑摩时发动机的动力同时通过液力传动和机械滑摩传动两条路线传递,它能够在大范围内提高传动效率。文中推导了汽车自动变速系统在滑摩过程中的功率平衡方程,并利用该方程计算了滑摩过程的控制油压,选择合理的滑摩控制区域能够显著提高自动变速传动系统的传动效率和缓冲、抗振性能。该控制区域应该从发动机的扭振状况、变矩器离合器的滑摩率和功率分配比、变矩器的输出特性以及自动变速系统的换挡规律多个方面进行考虑。     

混联式混合动力SUV多能源总成CVT控制系统研发

介绍了CVT混联式混合动力SUV车(CFA6470HEV)总体结构及整车控制策略,设计了基于TMS320F2812数字信号处理芯片的多能源总成控制系统硬件,移植了μC/OS_Ⅱ操作系统并提出了整车控制系统的任务分配,最后通过台架试验完成对多能源总成控制系统的各功能模块的测试,为整车能源管理系统开发提供了有效软硬件平台和理论依据.     

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.     

液力变矩器工作时汽车燃油消耗量的实用算法

根据发动机的万有特性曲线和变矩器的无因次特性及泵轮转矩曲线。得出了联合装置的输入和输出特性，对输出特性中的燃油消耗率进行二元曲面拟合，就可计算出整车的百公里燃油消耗量，提供了一种计算液力变矩器工作时燃油消耗量的实用方法。     

Development of a time-to-digital converter IC for laser radar

A CMOS time-to-digital converter IC with half-nanosecond resolution by inverter-delay-time has been developed for measuring time intervals with a fully digital circuit. A new circuit “ring-gate-delay” system using two revolution counters can make the area of the circuit far smaller than it would be without them. Accuracy is assured through digital processing with a 2 MHz crystal clock reference. A time resolution of 0.5 ns and a measurement range of 0–2200 ns using 1.5 μm CMOS were confirmed.     

无极变速器在轿车中的应用与发展动向

研究了无级变速器的发展历程,并分析了几种典型无极变速器的结构。从专业的角度阐述了它目前所存在的优点与缺点以及目前国内市场上的应用现状。通过分析与预测说明无极变速器在未来中国市场上将起着重要的作用。无级变速器必将是未来中国变速器市场上的"主力军"。     

新型可变气门升程和定时机构的大功率、宽扭矩高效发动机

本文介绍一种新研制的具有高速和低速凸轮的双凸轮式可变气门系统。另外制造了一台应用该系统的1.2L双顶置凸轮式(DOHC)试验发动机,并将其装于2L级轿车上。对在该车上使用新机和原机的试验结果做了比较。试车表明,前者在驾驶性能、燃油经济性和噪音测试诸方面均优于后者。本文论述了这种可变气门系统的机理、运行和测试结果,并介绍了1.2L试验发动机和装有该发动机的轿车。     

Effect of radial interference on torque capacity of press- and shrink-fit gears

Some gears in an automobile transmission have to be mounted by being press-fitted on a shaft instead of splines. The torque capacity of the press-fitted gear will be proportional to the radial interference. The excessive interference, however, will increase the gear radial deformation. In this paper, the press- and shrink-fit and the subsequent torque capacity test were investigated by finite element analysis, theoretically and experimentally. The static and dynamic coefficient of friction were determined.     

Disturbance compensation with a torque controllable steering system

Via a conventional steering system the driver perceives desired and disturbing effects such as road feedback and resonance effects, respectively. They appear with overlapping frequency spectra within the driver's steering torque. This paper introduces a control algorithm that is suppressing periodic disturbances without affecting useful steering road feedback attributes as well as regular power assistance characteristic. This is realised by an integrated torque actuator within the steering column in conjunction with a conventional Hydraulic-assisted Power Steering (HPS) system.     

Performance estimation model of a torque converter part I: Correlation between the internal flow field and energy loss coefficient

The objective of this paper is to improve the performance estimation model of the internal flow field of a torque converter. Compared with performance experiment results, the converter based on the one-dimensional model does not satisfy the performance requirements demanded in practice. Therefore, we need to develop more predictable and reliable performance estimation models. In order to obtain shape information on three-dimensional blade geometry, a process of reverse engineering conducts a torque converter assembly, impeller, turbine and stator. In addition, a CFD simulation including mesh generation and post-processing was carried out to extract equivalent parameters from the internal flow field. The internal flow field can be explained by analyze the correlation between a performance estimation model and CFD analysis. The equivalent performance model adopts the variation of energy loss coefficients for a given operating condition according to the application of a changing energy loss coefficient by the least mean squares method. The estimated equivalent model improves the agreement in performance between experiments and the theoretical model. This model can reduce the error to within about 3 percent. Furthermore, this procedure for predicted performance achieves eminence in the estimation of the capacity factor.     

Disturbance compensation with a torque controllable steering system

Via a conventional steering system the driver perceives desired and disturbing effects such as road feedback and resonance effects, respectively. They appear with overlapping frequency spectra within the driver's steering torque. This paper introduces a control algorithm that is suppressing periodic disturbances without affecting useful steering road feedback attributes as well as regular power assistance characteristic. This is realised by an integrated torque actuator within the steering column in conjunction with a conventional Hydraulic-assisted Power Steering (HPS) system.     

汽车无级变速（CVT）技术的发展概况与未来趋势

1前言 目前在汽车上广泛使用的自动变速技术是将液力变矩器和行星齿轮系组合的自动变速器技术,在主要汽车制造商生产的城市用车中的平均装车率已经达到70%.但是液力变矩器和行星齿轮系的组合有着明显的缺点:传动比不连续,只能实现分段范围内的无级变速;液力传动的效率较低,影响了整车的动力性能与燃料经济性;增加变速器的档位数来扩大无级变速覆盖范围,就必须采用较多的执行元件来控制行星齿轮系的动力传递路线,导致自动变速器零部件数量过多,结构复杂,保养和维护不便.所以汽车行业早就开始研究其它新型变速技术,无级变速(CVT)技术就是其中最有前景的一种.     

某车金属带式CVT钢球滑道的设计

在国内某车金属带式无级变速器开发中,介绍如何进行钢球滑道截面形状的选取和应力计算,以及钢球的安装尺寸确定。通过运用有限元法,计算出钢球滑道在转矩和金属带夹紧引起的载荷共同作用下的最大挤压应力;指出钢球在变速过程中的移动仅是与之相接触可动轮移动距离的一半,钢球应满足最大速比状态和最小速比状态时的几何安装要求。     

Improvement of prediction accuracy for torque converter performance: One-dimensional flow theory reflecting the stator blade geometry

Specific fuel consumption is a key word these days, and the torque converter can play an important role in improving it. This makes it essential to improve the accuracy of methods for predicting torque converter performance. In this work, the accuracy of performance predictions ws improved by replacing the flow angle and total pressure loss in the angular momentum theory with corresponding values obtained by analyzing the flow around the stator using a general flow analysis code. A quick and highly accurate prediction of torque converter performance is made possible with this method.