关键词: 汽油/CNG 双燃料发动机；供气系统；先导电磁阀；气轨压力低

Abstract: This paper introduces the compressed natural gas (CNG) gas supply system of a dual-fuel engine and the structural principle of the pilot solenoid valve integrated on the pressure reducer assembly. Pressure sensors are added for monitoring, and INCA software is adopted to investigate the fault of low gas rail pressure after cold start of the CNG gas supply system for a vehicle engine. Monitoring data indicate that the closing of the solenoid valve is the direct cause of low gas rail pressure. By checking the rail pressure before engine start, micro-leakage in the system is confirmed. Analysis based on the pressure-building principle of the pilot solenoid valve shows that the root cause of the fault is system-which prevents rail pressure establishment prior to engine start. After engine start, vehicle load rises, stable pressure build-up fails beneath the solenoid valve, and the valve core closes under the action of gas force. Eliminating the leakage resolves the low gas rail pressure issue during cold start of the vehicle.

Key words: gasoline/CNG dual-fuel engine; gas supply system; pilot solenoid valve; low rail pressure