Design and Analysis of a Transmission Hydraulic System for an Engine-Flywheel Hybrid-Vehicle

Unlike hydraulic systems of conventional automotive transmissions, the hydraulic system of a hybrid vehicle must cope with large variations of pressure as well as flow. If supplied by traditional pump configurations, either fixed or variable displacement, the system will incur substantial efficiency losses. This paper presents a feasibility study of a dual-pump hydraulic supply system which consists of a low-volume fixed-displacement pump and a high-volume variable-displacement pump. The analysis addresses the dynamic characteristics of this system along with its sensitive design areas.