The Study Of Adaptive Pressing Mechanism Of CVT(BVT) In Vehicle

Because environmental pollution and energy shortage are increasingly more serious, energy conservation and environment protection are the developing direction in future, and a continuously variable transmission (CVT) with good fuel economy is getting wide attention from the industry. To this end, a new BVT has been proposed by our group. In this paper, the theoretical analysis, simulation analysis and experimental study have been done for the adaptive pressing mechanism with Archimedes helicoid surface in BVT, and the main research works are as follows:(1) According to the performance requirements of pressing mechanism in BVT, the relevant literature at home and abroad was consulted. The shortcomings of adaptive pressing mechanism with balls and V-grooves in the first generation prototype were pointed out, and the research content and goal of the paper were proposed.(2) In order to compare the performance of two kinds of adaptive pressing mechanisms with helicoid surface and with balls and V-grooves, the force analysis and strength analysis were performed respectively, and the structure parameters of the adaptive pressing mechanism with helicoid surface were optimized. It was verified that the performance of two kinds of mechanisms can meet the requirements of vehicle driving conditions, while the former has the advantages of small transmission coefficient, strong shock resistance and good adaptive pressing property.(3) Using the software ABAQUS, the contact stress analysis for two kinds of mechanisms under vehicle driving conditions was respectively carried out. Comparison of calculation results shows that the adaptive pressing mechanisms with helicoid surface can meet the requirements of vehicle driving conditions, and has smaller contact stress. Simultaneously, by comparison between the theoretical analysis and finite element analysis, results show that the two calculations are roughly equal, which can be used as a basis for the strength check of the adaptive pressing mechanisms with helicoid surface.(4) Using the simulation software of virtual prototyping, ADAMS, and the multi-flexible-multibody system dynamics, the models of multi-flexible-body system for two kinds of mechanisms were established respectively. Then the simulation study was performed and the simulation curves of pressing mechanisms under the vehicle driving conditions were obtained. Through comparing, the validity of theoretical calculation and simulation experiment was verified, and the adaptive pressing mechanisms with helicoid surface has more superior adaptive pressing performance.(5) The no-load test and load test for the second-generation physical prototype of BVT with the adaptive pressing mechanisms with helicoid surface were done on the test bench. The experimental, theoretical and simulation results show that the adaptive pressing mechanisms with helicoid surface has the advantages of large carrying capacity and stable and reliable pressing performance, which can meet the pressing needs of BVT.The reliability of the adaptive pressing mechanisms with helicoid surface under the vehicle driving conditions is verified in the paper, and the research results can provide a reference for the further development of BVT.