Working Performance and Feasibility Evaluation of Four-stroke Compressed Air Engine

Research on compressed air engine (CAE) is of great value under the background of energy conservation, emission reduction, and environmental protection in recent years. Compared with traditional internal combustion engine (ICE), four-stroke compressed air engine (F-s CAE) has no combustion and explosion process during operation, and the use and emission of working medium is clean air. Here, to deeply discuss the working performance of the F-s CAE, first, we expound a working principle of the F-s CAE. In addition, we analyze the control strategy of the electronic control unit (ECU) system and carry out a calibration test for the CAE. Meanwhile, we further conduct a feasibility analysis to verify its scientificity as the power of means of transport. In the test process, engine speed, supply pressure, port timing (intake advance angle and intake sustain angle) can directly affect the working performance. Results suggest that the overall effective power and single cylinder compressed air consumption increase with increase in the engine speed, while the average effective torque changes oppositely. Kinetic and dynamic characteristics are much better after supply pressure increased. The dynamic performance improves with the decrease in intake advance angle, but subsequently goes down when the intake advance angle decreases from 10 degrees CA to -90 degrees CA, and the intake advance angle as -70 degrees CA is optimal. Overall, an intake sustain angle of 80 degrees CA is more conducive to improving CAE dynamic performance compared to a relatively small intake sustain angle. The research results will be useful for further design and improvement of the F-s CAE.