MULTI-DOMAIN MODELING AND SIMULATION OF DRIVE TRAIN OF HYDRAULIC HYBRID VEHICLE

Abstract

For the last three decades clean automotive technology is the most focused area for the engineers. Clean environment is not a new slogan and there are major contributions put by engineers in the field of automotive design and engineering to protect the environment. Compressed natural gas (CNG) and air engine were introduced to contribute towards the stated objective and the former engine, enhanced the life of conventional diesel or petrol engines to some extent. However, conventional engines due to their power and high torque were never fully replaced. Thus hybrid concepts were introduced and electric hybrid was the first prime vehicle that fulfills the demands of urban driving but demands of high torque remained the problem for engineers. From the last decade engineers are working on a hybrid vehicle that uses the hydraulic energy to deliver torque and power. Lately, hydraulic hybrid vehicle was invented for urban drive which saved 50% fuel. There are two fluid tanks known as high pressure tank or accumulator and low pressure tank or reservoir. The hydraulic pressure energy which is stored in accumulator is used to turn the wheels. After useful high pressure fluid drops down the certain level then engine turns on and excess energy (also during braking) is stored in accumulator. In this work comparison of fuel consumed by diesel engine only and diesel hydraulic hybrid was determined. An algorithm is presented which measures the fuel consumption of hydraulic hybrid vehicle. At the end a comparison between hydraulic hybrid and conventional diesel engine is presented for urban driving conditions and also for highway cycle. The aim is to model the system and then simulate its behavior. For this bond graph technique will be used which theoretically represent the saved energy in the form of graphs. Bond graphs are a domain-independent graphical description of dynamic behavior of physical systems. This means that systems from different domains (e.g. electrical, mechanical, hydraulic, acoustical, thermodynamic and material) are described in the same way. The basis is that bond graphs are based on energy and energy exchange. The research can be used for bond graph application in the field of automotive, hybrid systems. Here hybrid systems comprised of hydraulic and mechanical power sources.