Development of motor-driven pump for drivetrains
～Features compactness and high efficiency～

JTEKT Corporation has developed a compact, highly efficient motor-driven pump for drivetrains equipped with idling-stop capability (engine stoppage in place of idling), a technology that contributes to the improvement of automobile fuel efficiency.

Conventionally, the hydraulic pressure required for clutch action in automatic transmissions and continuously variable transmissions is created by means of an engine-driven pump, and therefore in the case of vehicles possessing such a pump along with idling-stop capability, hydraulic pressure ceases during idling-stops. But the lag in hydraulic response causes the problem of gear engagement shock when the vehicle begins moving after the engine restarts. If the drivetrain is equipped with a motor-driven pump, however, hydraulic pressure is maintained at a minimal level during idling-stops, which prevents vehicle initial-movement shock after the engine restarts.

Because motor-driven pumps for drivetrains are installed in the engine room, they must have a compact design, and furthermore because they operate even when the engine has stopped, they must exhibit high efficiency to avoid placing significant load on the battery. Regarding the motor-driven pump developed this time, it utilizes a brushless, sensor-less motor. Also, its pump and controller have been integrated into a single structure, it features world-level compactness for pumps of the same output, and design optimization of each element enables it to exhibit high efficiency in the hydraulic pressure range used most frequently.

JTEKT plans to create a series of these motor-driven pumps for application not only with idling-stop technology but also with hybrid vehicles, which require operation of a motor-driven pump when the vehicle’s electric motor is serving as the power plant, and aims for sales of 700 million yen in 2012.