Test stand for modelling hydraulically controlled continuously variable transmission
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Lodz University of Technology
Publish date: 2017-12-30
The Archives of Automotive Engineering – Archiwum Motoryzacji 2017;78(4)
A test stand making it possible to analyse the hydraulic processes that take place in the hydraulically controlled automotive continuously variable transmission (CVT), operating with a pushbelt or chain, has been described. The test stand was developed at Lodz University of Technology (TUL), Department of Vehicles and Fundamentals of Machine Design. The transmissions of this type and the transmission ratio control systems being in use at present have been briefly characterized. In the next part of the article, attention has been focused on the hydraulic control system, which is now most popular. In consideration of the known drawbacks of the classic system with a single fixed-displacement pump, a new engineering solution has been proposed to improve the system efficiency. The test stand shown here makes it possible to carry out various tests of the new solution mentioned above. The method of obtaining similarity between the test setup and the arrangement of elements in a real Jatco CVT7 unit has been presented. This has been achieved by appropriate selection of the type and geometry of the lever system that interconnects the movements of two actuators on the test bench. A new balance of forces exerted by the actuators is achieved for every proportion of the pressures and the corresponding displacements on the test stand are proportional to the displacements in the reference CVT. Some test results have been given as an example.