Search Results

A gasoline engine with the expansion ratio of 14:1 for better efficiency is presented. The engine has intake control rotary valves to reduce the effective compression ratio for knock avoidance and to cotrol power output. Computer simulation, based on the method of characteristics and quasi-steady model, indicated the advantage of the rotary valve system as well as the optimum design of the valve actuation. Experimental results showed a good agreement with the prediction, and BSFC of under 240 g/kWh was achieved at load higher than 50%. However, at very light load, the conventional throttle valve operation was inevitable, which somewhat worsened the advantage of the new system. The mileage for a car driving cycle and constant speeds were also estimated and it was forecast that optimized supercharging would significantly benefit the fuel economy.

This paper deals with a new type of Miller cycle engine which is installed with an intake control rotary valve, and presents the experimental investigation on the test engine which was undertaken to examine the capacity of supercharging as well as fuel economy in the application of the new system to small-sized gasoline engines. An experimental investigation on the test engine with some simple modification to a conventional engine revealed that the intake control rotary valve installation is quite effective to control the virtual compression ratio. It was ascertained by an external supercharging test that reduced compression ratio with constant expansion ratio allowed the test engine to obtain a considerably higher level of torque in the low engine speed range than had been attained in conventional supercharged engines without any increase in fuel consumption.