Use of electromagnetic clutch water pumps in vehicle engine cooling systems to reduce fuel consumption

In general, when the internal combustion engine of a vehicle is started, its operationally connected cooling system provides excessive cooling, resulting in unnecessary energy consumption and excessive emission of exhaust gas. If the rotational speed of the engine is high, the excessive cooling causes the combustion efficiency to decrease. Therefore, better control of the operating temperature range of the engine through use of an active cooling system can achieve better fuel economy and reduction of exhaust gas emission. Effective control of the cooling system in accordance with the operating conditions of the engine can be realized by changing the mass flow rate of the coolant. In this study, we designed electromagnetic clutch water pumps that can control the coolant flow. We made two types of water pump: (1) a planetary gear (PG)-type water pump which can reduce the rotation speed of the water pump by 65%, compared with a pulley; and (2) an on/off-type water pump which can completely stop the rotation of the impeller. The performance evaluation of these pumps consisted of a warm-up test and the New European Driving Cycle (NEDC). Warm-up test results showed that the time required to achieve a temperature of approximately 80 °C with the PG water pump and the on/off water pump was improved by 7.3% and 24.7% respectively, compared with that of a conventional water pump. Based on the NEDC results, we determined that the fuel economy of the engine using the PG water pump and the on/off water pump was improved by 1.7% and 4.0% compared with the fuel economy when using the conventional water pump. The application of clutch water pumps is expected to contribute to the improvement of engine cooling system performance, because their effect in reducing the fuel consumption rate is similar to that of an electric water pump.