체크밸브 유무에 따른 HEV용 유압제어시스템의 유압변화에 대한 연구

An automatic transmission (AT) shifts gears by controlling hydraulic control valves. Sufficient supply of an oil for running AT, in general, is received from a mechanical oil pump. However, for a hybrid electric vehicle, AT is consists of an parallel oil supply system added an electric oil pump for controlling idle stop-and-go system. In this system a check valve as well as clearance of pump is required for blocking the reverse flow of oil in a fluid power circuit. While operating a hydraulic system without and with a check valve, the current study provides the variation of independently hydraulic property for each oil pump two different oil viscosities at 40℃ and 85℃. As a result, pump response to hydraulic control and the flow rate of oil pressure in this system was improved. It obtained the desired oil pressure at 40℃ because of the higher viscosity of an oil. On the other hand, instead of running equipped with a check valve, running without a check valve at 80℃ had lower hydraulic property and pump response because of the reverse flow of oil at the beginning.