关键词: 燃气车；废气再循环系统；发动机；潜在失效

Abstract: China's six stage natural gas engine adopts the technical route of combining three-way catalytic converter and theoretical air-fuel ratio. Compared with the fifth stage lean combustion in China, the heat load and knock in the cylinder are significantly increased, and the fuel gas consumption is also significantly increased. In order to improve the heat load and knock of natural gas engine and improve the fuel economy, the exhaust gas re-circulation system is introduced into natural gas engine. The main component of natural gas is methane. After combustion, the moisture content in the engine exhaust is high. In extremely cold environment, after the exhaust gas is cooled by exhaust gas re-circalation (EGR) cooler and enters the intake system, there may be potential failure modes of icing in the exhaust gas re-circulation valve, gas mixer, throttle and other parts. This paper introduces the causes of icing after adding exhaust gas re-circulation system, vehicle operation performance and cold zone test verification components, so as to identify the reliability risk in advance and ensure the reliable operation of vehicles in extremely cold environment.

Key words: Gas vehicle; Exhaust gas re-circulation system; Engine; Potential failure