Three typical operating conditions of high

medium and low loads were selected to experimentally investigate the effects of intake throttle and fuel injection strategies on the combustion process

emissions

fuel economy and diesel oxidation catalyst(DOC) inlet temperature of a light-duty diesel engine

obtaining a heating strategy of the DOC inlet temperature at all operating conditions. The results showed that the intake air flow declined with the decrease of the opening of the intake throttle valve

which had a significant effect on the in-cylinder working process: decreased compression pressure

delayed combustion start timing

reduced maximum combustion pressure and decreased cyclic indicated work. HC emission was suppressed and other emissions were deteriorated. The DOC inlet temperature was effectively increased

and the lighter the load

the more significant the temperature rise. A test of fuel injection pattern coupled with intake throttle was conducted. The test results show that with the delay of the main fuel injection timing

the ignition delay is shortened

the weight of the post combustion increases and the DOC inlet temperature rises slightly. The DOC inlet temperature is raised by increasing the fuel quantity of the close post-injection. The DOC inlet temperature rises first and then drops with retarding the close post-injection timing. There is an optimum close post-injection timing. According to the distribution of the engine exhaust temperature in the whole operation range

the strategy of controlling the DOC inlet temperature is proposed.