Huanxiang Xu

Research on a pneumatic hybrid engine with regenerative braking and compressed-air-assisted cranking

With the aim of improving the energy efficiency of conventional vehicles, this paper proposes a pneumatic hybrid engine concept, which features regenerative braking and compressed-air-assisted cranking functions. In the regenerative braking mode, the engine works as a two-stroke compressor and converts the kinematic energy of the vehicle into compressed air. In the two-stroke air motor mode, a throttle valve in the intake manifold is used to block the ambient air, and an electropneumatic solenoid valve is employed to control the compressed-air injection. The compressor mode is modelled on the basis of thermodynamics and gas dynamics theories and is improved according to the bench test results of a single-cylinder engine converted from a two-cylinder diesel engine. Transient engine cranking tests are also conducted and are discussed. Urban driving-cycle simulation results show that the fuel consumption of a light-duty vehicle with a pneumatic hybrid system can be reduced by 8%.

Preliminary study on compressed air powertrain of a rescue vehicle for mine accidents

This paper investigates the feasibility of applying a compressed air powertrain to mine rescue vehicles, which require strict explosion-proof and flame-proof characteristics. Based on both simulation and preliminary tests of a single-cylinder air-powered engine prototype, the concept of compressed air powertrain for a rescue vehicle is proposed. Compared to conventional internal combustion engines, the exhaust emissions of the proposed air-powered engine concept are innoxious and its gas temperature is very low, which guarantees the safety and explosion-proof requirements. Preliminary selection and matching of both a transmission and final gear reduction are carried out, considering vehicle traction and air consumption performance characteristics. Simulation results show that given properly designed drivetrain gear ratios, the air-powered rescue vehicle can reach a speed of 7 km/h with gear 1 on a 30% slope road. Compared to current products, its feasibility in driving mileage and traction performance are further confirmed.