Spark ignition engines perform with low power efficiency and low fuel economy for which the throttling loss is the main reason. This paper introduces a new kind of intake control system-series valve speed control system that consists of two intake valves connected in series. It is operated without throttle to reduce the engine intake loss and thereby improve fuel economy under medium- and low-load working conditions. Through experiments, we confirm that compared with the basal spark ignition engine, the spark ignition engine with series valve speed control system can reduce fuel consumption, and the maximum fuel consumption rate can be increased up to 12% at the engine speed of 3000 r/min.
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