Pump apparatus and control method for controlling the pump apparatus

A pump apparatus for supplying a working fluid to a steering apparatus for a vehicle, the pump apparatus comprising:

• a pump housing having a pump element accommodating portion;
• a drive shaft rotatably supported by the pump housing;
• a cam ring movably disposed in the pump element accommodating portion;
• a pump element disposed within the cam ring, the pump element being rotationally driven by the drive shaft to suck the working fluid and discharge the working fluid sucked and vary a specific discharge quantity which is a discharge quantity of the working oil per one rotation of the pump element in accordance with variation in eccentric amount of the cam ring with respect to the drive shaft and
• a solenoid which is drivingly controlled on a basis of a steering condition and a vehicle speed, the solenoid being operated to control the eccentric amount of the cam ring,
• wherein the solenoid is controlled to execute a flow rate reduction control during cranking of an engine of the vehicle in which the cam ring is allowed to move in such a direction as to reduce the specific, discharge quantity, and
• wherein the solenoid is controlled such that in a case where a rotational speed of the drive shaft is constant, the specific discharge quantity is minimized when the solenoid is in a de-energized state, and the specific discharge quantity is increased as an amount of electric current flowing through the solenoid becomes larger.

A pump apparatus for supplying a working fluid to a steering apparatus for a vehicle, the pump apparatus comprising:

• a pump housing having a pump element accommodating portion;
• a drive shaft rotatably supported by the pump housing;
• a cam ring movably disposed in the pump element accommodating portion;
• a pump element disposed within the cam ring, the pump element being rotationally driven by the drive shaft to suck the working fluid and discharge the working fluid sucked and vary a specific discharge quantity which is a discharge quantity of the working oil per one rotation of the pump element in accordance with variation in eccentric amount of the cam ring with respect to the drive shaft,
• a steering condition detecting means for detecting or calculating a steering angle, a steering angular velocity or a steering angular acceleration and outputting a steering condition detection signal indicative of the steering angle, the steering angular velocity or the steering angular acceleration;
• a solenoid which is operated to control the eccentric amount of the cam ring;
• and
• a control unit configured to determine a solenoid driving signal to drivingly control the solenoid in accordance with the steering condition detection signal and a vehicle speed and output the solenoid driving signal to the solenoid,
• wherein the control unit is configured to control the solenoid so as to allow the cam ring to move in such a direction as to reduce the specific discharge quantity during cranking of an engine of the vehicle.