Vane pump device

Abstract

A vane pump device includes: a rotor supporting 10 vanes movable in a rotation direction; and a cam ring having an inner circumferential surface facing an outer surface of the rotor. A fluid-suction step where transits to a fluid-discharge step by changing the pump chamber capacity in response to the rotation angle, as a result of the change in the distance from the rotation center to the inner circumferential surface of the cam ring in response to the rotation angle. A starting angle, at which the distance starts increasing after a same distance segment has reached a predetermined rotation angle, has a rotation angle difference of 2.5 degrees or less with respect to a center angle that equally divides a rotation angle at which a downstream-side end portion in the discharge port is formed and a rotation angle at which an upstream-side end portion in the suction port is formed.

1 . A vane pump device comprising:
 a rotor rotating while supporting 10 vanes to be movable in a rotation radius direction; and   a cam ring having an inner circumferential surface facing an outer circumferential surface of the rotor, wherein   a change in a distance from a rotation center of the rotor to the inner circumferential surface of the cam ring in response to a rotation angle of the rotor causes a change in a capacity of a pump chamber, which is partitioned by the outer circumferential surface of the rotor, the inner circumferential surface of the cam ring, and adjacent two of the 10 vanes, in response to the rotation angle, the change in the capacity of the pump chamber makes transition to at least a suction step in which working fluid is sucked into the pump chamber and a discharge step in which the working fluid is discharged from the pump chamber, a starting angle, which is a rotation angle at which the distance starts to increase after a segment with the same distance has reached a predetermined rotation angle, has a rotation angle difference of 2.5 degrees or less with respect to a center angle when the center angle is assumed to be an angle that equally divides the rotation angle at which a downstream-side end portion in a discharge port is formed and the rotation angle at which an upstream-side end portion in a suction port is formed, and, when it is assumed that a rotation angle of the center angle is 0 degrees, a downstream-side direction in a rotation direction is positive, and an upstream-side direction in the rotation direction is negative, the rotation angle at which the downstream-side end portion in the discharge port is formed is equal to or less than the rotation angle at which the segment with the same distance starts.