主動式雙無段變速器動力分配系統對車輛動態行為影響分析

Abstract

本論文研究所稱之雙無段變速系統(Dual Continuously Variable Transmission, DCVT)，係由兩組無段變速器(Continuously Variable Transmission, CVT)組合而成。系統在輸入端相連，並分別輸出至兩側車輪，類似於荷蘭汽車製造商DAF於1958年搭載於DAF 600車型之Variomatic傳動系統。隨著近年CVT技術的演進，目前已有主動控制CVT減速比之技術，不但可改善車輛性能還可同時達成較高的燃油經濟性。若將上述之主動式CVT用於DCVT系統，可達成主動差速控制及動力分配，提升駕駛安全性及車身動態性能。本研究透過建立主動式雙無段變速系統(Active Continuously Variable Transmission, ADCVT)之動態模型，比較該系統與傳統之實軸、差速器、限滑差速器等動力分配系統特性之差異。並透過Matlab撰寫程式模擬搭載該系統之車輛在轉向時的動態行為，比較該系統在定速行駛時輸入不同轉向角度、定轉向角度不同車速時車輛的轉向半徑變化及車輛失去抓地力時的動態反應。結果顯示ADCVT系統可透過參數調整提升車輛轉向性能，並可在車輛失去抓地力時保有限滑功能，不致使車輛失去動力。

The dual continuously variable transmission(DCVT), which investigated in this study, is assembled by two CVTs. At the primary pulley side, two CVTs are connected by one straight shaft and share the same rotation speed. However, two CVTs transmit power to two wheels independently. Although the DCVT system proposed in this paper is similar to the “Variomatic” system, which was developed by the Dutch car manufacturer DAF more than 50 years ago. With the advanced active CVT control widely used in modern car industry, the DCVT system may be able to achieve better fuel economy than the mechanical controlled Variomatic system. In addition, the active yaw moment control also becomes available to the DCVT system with active CVT control now to improve the driving safety and the vehicle performance. In this study, the dynamic models of the ADCVT system and other conventional differential system including solid-axle, open-differential are built. Split-mu test and J-turn test under different parameter including speed, steer angle, ADCVT gain and ratio-changing speed are carried out to simulate and compare the basic system characteristics of these systems. The simulation results show that the ADCVT system possesses limit-slip function to prevent loss of traction while one driving tire slips. And with proper system control, the system is proved to be able to improve the handling performance of vehicle.