Application of Hydro-mechanical Continuously Variable Transmissions in Agricultural Tractors

摘要

The synthetic performance of agricultural tractors can fundamentally be improved by using continuously variable transmission (CVT). The hydro-mechanical continuously variable transmission (HMCVT) is a new type continuous variable transmission device and suitable for agricultural tractor and engineering vehicle, which has several characteristics such as gear high power, top efficiency, small volume and gear steadiness. The working principle and the characteristics of hydro-mechanical transmission (HMT) are introduced in this paper. The structural schemes of several typical HMCVTs for agricultural tractors are specialized and each characteristic of them is synchronously analyzed. According to the working requirements of agricultural tractors, the main problems of the HMCVT, which are the selection of structural schemes and structural parameters and the automatic control system, are explained. The HMCVT can adapt automatically to the change of the load and driving resistance of tractor, ensure the engine to work in the maximum power point. As a result, agricultural tractors with the HMCVT demonstrate greatly improved productivity. Furthermore, it can be helpful to improving the power performance, fuel economy and working efficiency of tractor. This paper has some reference significance to the development, design and selective assembly of the HMCVT for agricultural tractors.