Development Story

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.

Hybrid vehicles, electric vehicles and idling stop systems—these and other recent advances in fuel economy all share the same problem: incompatibility with conventional mechanical oil pumps. The solution comes in the shape of electric oil pumps.

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.

Nidec Tosok's silent internal gear pumps—equipped with high-efficiency brushless DC motors and inverters using original software that makes sensor-less high-speed start-up possible—achieve industry-top-level performance.

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.

By leveraging the synergy of the individual companies in the Nidec group, system-level development of electric oil pumps becomes possible.

Developer's Comment

The secret behind the success of our electric oil pump modules for hybrid vehicles that we started mass-producing in 2013 lies in the high performance of all the individual components—motors, inverters, pumps and more. In the future, the market for electric oil pumps—replacing their mechanical counterparts—will see significant growth as a result of stricter fuel economy regulations, leading to tougher competition. Through close cooperation with the other members of the Nidec group—including Nidec, the world's top manufacturer of brushless DC motors and the head of the company group, Nidec Elesys with strong capabilities in electronic circuits for automobile applications, and NIDEC GPM with a long history of manufacturing mechanical pumps—and joint research with universities, Nidec Tosok seeks to significantly expand its share in the electric oil pump market.