当量燃烧车用天然气发动机降低热负荷策略研究与试验

Experiment and Study of Heat Load Reduction Strategy of Natural Gas Engine with Equivalent Ratio Combustion for Vehi-cle

摘要: 自GB17691国六法规实施以来，第一批配备EGR的当量燃烧天然气发动机已使用一年时间，从市场应用效果来看，由于我国天然气的硫含量很高，长时间的高温状态将会在内部形成硫酸，同时天然气燃烧后水蒸气特别多，在高温、多水、硫酸的情况下，零部件极易腐蚀，导致EGR零部件市场故障率很高。在此背景下，本文在开发某当量燃烧车用天然气发动机时，通过采用缸盖双层水套结构，设计缸体交叉水道结构，优化活塞的机油冷却腔位置，改进燃烧室形状和压缩比，增加水泵流量，活塞、气门采用新材料等多项措施，解决了无EGR当量燃烧天然气发动机热负荷难题。为了提高开发效率，特别对活塞的热负荷问题，进行了仿真与温度测试。最后通过整机825小时的可靠性试验验证，发动机可靠性满足要求。

Abstract: Since the implementation of the GB17691 China Six Emission Standards, the first batch of equiva-lent combustion natural gas engines with EGR has been running for nearly one year. From the mar-ket application effect, because the sulfur content of natural gas in our country is very high, so the long high temperature state time will lead to sulfuric acid production inside. At the same time, the natural gas will produce more water vapor after combustion, and in the case of high temperature, multi-water and sulfuric acid, the parts are easy to corrode, causing high market failure rate of EGR parts. In this situation, when discussing natural gas engine with equivalent ratio combustion for ve-hicle, this paper solves the problem of heat load of natural gas engine without EGR equivalent com-bustion by adopting cylinder head double layer water jacket structure, cylinder block cross channel structure, optimizing piston oil cooling chamber structure, improving combustion chamber shape and compression ratio, increasing pump flow rate, adopting new materials for piston and valve. In order to improve the development process efficiency, especially the heat load of piston, simulation and temperature test are adapted. Finally, based on the whole machine 825 hours reliability test verification, engine reliability is proved to meet the requirements.