electric pump

Abstract

An electric pump includes a pump body, a sensorless brushless motor, and a control portion controlling the motor to perform a constant current control and a constant voltage control to discharge a necessary discharge amount of an operation fluid from the pump body, the control portion controlling the motor to switch from the constant current control to the constant voltage control at a predetermined temperature of the operation fluid and at a predetermined motor applied voltage. The control portion controls the motor to switch from the constant current control to the constant voltage control at a motor applied voltage which is higher than the predetermined motor applied voltage when a temperature of the operation fluid is lower than the predetermined temperature to discharge the necessary discharge amount of the operation fluid from the pump body.

Description

technical field [0001] The present invention generally relates to electric pumps. Background technique [0002] In consideration of global environmental problems, known vehicles, such as automobiles, have been provided with an idle stop control function for stopping an engine when stopping for a short time at an intersection and the like, and preventing exhaust gas and gasoline consumption. When the idle stop control function is executed, the engine stops running. However, in this case, since it is still necessary to maintain the oil pressure level of the transmission, an electric pump that can be driven to supply oil (an example of working fluid) even when the engine is stopped is used to maintain the oil pressure level of the transmission . [0003] Since the electric pump is provided in the engine room, it is required that the electric pump operates safely at high temperature. Therefore, a sensorless brushless motor (hereinafter referred to as a motor) is usually used ...

AI Technical Summary

Problems solved by technology

The required amount of oil cannot be supplied to the transmission because the amount of oil discharged from the electric pump is insufficient

In addition, because the induced voltage generated on the coil decreases with the decrease of the motor speed, the rotational position of the rotor cannot be detected, and at this time, the motor is out of step (step out)

In order to make the rotation speed of the motor equal to or higher than the preset amount at low temperature by applying a voltage equal to that applied to the motor at normal temperature, the motor needs to be oversized to generate a large amount of torque, so the motor space , weight and cost, electric pumps using sensorless brushless motors are ineffective

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