Nowadays, the demand for energy savings and reduction of greenhouse gases as well as unhealthy emission of automobile has been highly increased due to the rise of fuel prices and new environmental regulation for vehicle emissions. As a result, the development of hybrid vehicles to reduce fuel consumption and emissions is a prerequisite. Hybrid vehicles have three different system configurations; series, parallel and series-parallel. These configurations can be divided into electric hybrid and hydraulic hybrid. Hydraulic hybrids operate basically on the same way as electric hybrids, but they use a motor-pump instead of an electric motor-generator and a hydraulic accumulator rather than the battery pack to store recuperated energy. The electric hybrid is promoted and successfully applied to automobile industry. The high power density of hydraulic pumps/motors and hydro-pneumatic accumulators make hydraulic technology look promising for passenger cars and need be integrated in the vehicle industry due to its low price and the new developed units of high efficiency compared to electric machines. The aim of this paper is to introduce the development of using a Secondary controlled/ pressure coupling Hydrostatic Transmission (SC-HST) drivetrain to the new configuration of series hydraulic hybrid drivetrain which is called the Hydrid for use in passenger cars.
A key component in the Hydrid drivetrain is the Innas hydraulic transformer and the new technology of using floating cup principle in axial piston hydrostatic pumps, motors and transformers which gives a higher efficiency up to 98%. Moreover one of the big merits of using the Hydrid drivetrain is its ability to force the engine to run only under high loads at all vehicle velocities.
A simulation study for the well known secondary control hydrostatic transmission drivetrain and the new and distinct Hydrid drivetrain will be introduced. The work bench vehicle used in this study is mid size VW-Passat. The effectiveness of the energy saving of the Hydrid drivetrain compared to the traditional secondary control clearly was proven by a simulation model which is built in DSHplus software. In addition, a control strategy, which is used to control the Hydrid drivetrain to follow commands given by a driver and to optimize the energy saving process of the engine, is also proposed. The simulation results indicate that Hydrid drivetrain reduce the fuel consumption of VW-Passat in typical NEDC cycle by about 59%. |
