Electric Oil Pumps

Electric Oil Pumps Necessary for Hybrid-Mode Driving and Idling Stop Systems—the Keys to Lower Fuel Consumption

The trend toward lower fuel consumption that started with the middle east oil crisis in the 1970's has carried on into the 21st century at an ever increasing pace and countries around the world are gradually strengthening their fuel economy regulations. Consequently, automobile manufacturers have started devising various new concepts and mechanisms in order to meet these new stricter regulations. Electric vehicles powered by electric motors and batteries, hybrid vehicles combining combustion engines with electric motors, idling stop systems that shut down the engine while the car is standing still—numerous solutions designed to reduce the time that the engine is used, or even remove the engine altogether, have emerged as a result. These solutions all have one problem in common: incompatibility with conventional mechanical oil pumps. This became the catalyst for the arrival of the electric oil pump.

In 2013, Nidec Tosok launched their first electric oil pumps for hybrid vehicles. These pumps, capable of supplying oil even when the engine is switched off, are characterized by high voltage, high oil-pressure, high flow rate (100 V, 1 Mpa, 10 L/min) and 25% higher efficiency—ranking in the top tier of the industry—than equivalent products made by our competitors. In addition to using high-efficiency brushless DC motors, Nidec Tosok's HV oil pumps are also equipped with inverters using original control software that makes sensor-less high-speed start-up possible. The pumps themselves are internal gear pumps with an improved bearing construction designed to minimize torque loss. They also produce minimal noise and vibration due to reduced gear vibration.

The automobile industry is moving towards lower fuel consumption by minimizing the time that the engine is running:idling stop systems evolve into coasting stop systems (shutting down the engine during deceleration) and then further evolve into sailing stop systems (turning off the engine when the car is benefitting from inertia after acceleration). Another emerging trend is the expansion of the applications of electric oil pumps to include clutch disengagement, cooling and lubrication etc. Electric oil pumps are also seeing increased use in large hybrid vehicles resulting in a rise in demand for larger pump models. In this way, the stricter fuel economy regulations are having a positive impact on the growth of the electric oil pump market. In the future, we plan to further expand our lineup of electric oil pumps to include both compact and large models for continuously-variable transmissions, dual-clutch transmissions, EV traction motor cooling and many other applications.