A variable cooling system was developed for a scooter equipped with an air-cooled, four-stroke, and single-cylinder gasoline engine. In this system, slats of the louver, located at the inlet of cooling air, are opened or closed by an oil-temperature-sensitive actuator. These slats shut off the supply of cooling air when the engine is in cold state or is driven with a low load. These operations of the slats help the engine oil temperature increase and the workload of the cooling fan decrease when the vehicle is running with a low load. With those effects, reduction of the mechanical loss is made possible. In addition, shortened warm-up time enables reduction of the injection fuel amount. As a result, fuel economy improvement of 3.3%, when driven in Urban Driving Cycle, was realized.
Article of Honda R&D Technical Review Vol.30 No.1 (45 - 52)