拖拉机液力机械式无级变速器的研究

Study on Hydromechanical Continuously Variable Transmission for Tractors

提出了一种新的组合式无级变速传动方案——液力机械综合式无级变速传动 ,由综合式液力变矩器、链无级变速器、减速齿轮组及相应的操纵控制机构组成。用该传动方案改进设计拖拉机的传动系 ,设计出了具有良好性能的液力机械式无级变速器。通过液力变矩器可自动无级变速变扭以适应外界变工况作业 ;通过链无级变速器和负载换档可实现由驾驶员控制的无级变速 ,因而整车能实现可控自动无级变速 。

On the basis of studying the historical development & present situation of Continuously Variable Transmission (CVT) at home & abroad, a new combined continuously variable drive scheme was designed, i.e. a hydromechanical CVT. The new CVT is composed of a Single stage Twinphase Torque Converter (STTC), Continuously Variable Chain Transmission (CVCT),reducing gears and their corresponding Hydraulic Clamping & Control Systems (HCCS). The new CVT is employed to improve the main drive of Shanghai 50 tractor which has a broad application and high market share. The comprehensive hydromechanical CVT with fair good performance has been laid out by using the thoughts and methods of Green Design & CAD. The torque converter can change the speed and torque automatically and steplessly as the working occasion demands. The driver can also adjust the CVCT by means of the HCCS and shift under load to change the speed continuously. Thus, automatical & controllable continuously varying speed can be realized, which ensures the diesel engine to work always around at the rated condition with the best fuel economy & power performance. The study & design showed that the newly designed CVT can be utilized to improve the overall operation performance of tractors and analogous vehicles such as fuel economy, power performance, driveability, comfortability, safety, acceleration, field crossing, less toxic exhaust emission, etc.