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Modeling and Validation for the Hysteretic Behavior of an Automatic Belt Tensioner

BYD Auto Industry Company Limited-Pu Xu
South China University of Technology-Shangbin Long, Xuezhi Zhao, Wen-Bin Shangguan
Published 2019-06-05 by SAE International in United States
An automatic tensioner used in an engine front end accessory drive system (EFEADS) is taken as a study example in this paper. The working torque of the tensioner, which consists of the spring torque caused by a torsional spring and the frictional torques caused by the contact pairs, is analyzed by a mathematic analysis method and a finite element method. And the calculation and simulation are validated by a torque measurement versus angular displacement of a tensioner arm. The working torques of the tensioner under a loading and an unloading process are described by a bilinear hysteretic model, and are written as a function with a damping ratio. The rule of the action for the damping devices is investigated based on the simulation and a durability test of the tensioner. A finite element method for the tensioner without damping device is established. Then the radial deformation for the torsional spring under an unconstrained state is obtained. The analysis results have a good correlation with the measurements. The method presented in this paper is beneficial for…
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R410A Based Automotive Heat Pump System That Hits Cabin Heating Goal Successfully in -30 °C Extreme Ambient

BYD Auto Industry Company Limited-Xuefeng Chen
BAIC Motor Corporation, Ltd. New Energy-Kelvin Zhai
Published 2019-04-02 by SAE International in United States
To meet low ambient challenges on Battery based Electric Vehicles (BEV), it is necessary to employ heat pump systems on the HVAC systems. However, due to the boiling points limitation of the regular refrigerant R134A/R1234YF, even with Vapor Injection cycle (VI) added, due to -26°C Boiling Temperature (BT) limitation, it is still encountering serious challenges to meet -30 °C or lower ambient needs, although VI Heat Pump (VI H/P) may reach COP>=1.7 at ambient -18 °C. An alternative low BT refrigerant, R410A, plus VI participation, the combination provides potentials to operate in extreme low ambient like -30 °C. In order to find out the actual heating performance of R410A+VI, a demonstration fleet of three vehicles had been built up for road tests to compare each other, which consists of a traditional vehicle (ICE gas heating), a BEV with PTC water heating system (R134A) and a BEV with VI heat pump system (R410A). The testing area covers the coldest city in China such as Harbin, (-20°C), Yakeshi (-39 °C), The road tests have exhibited positive results…
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