Vane Pump With Substantially Constant Regulated Output

Abstract

A variable displacement vane pump is provided which is able to achieve a substantially constant output pressure in its regulated operation region. The longitudinal axis of the control spring of the pump is inclined, with respect to a plane through the rotational axis of the pivot and the contact point between the control ring and the control spring, and this inclination results in a reduction in the length of the moment arm between the spring and the pivot when the control ring of the pump is moved from the maximum displacement position to the minimum displacement position. By reducing the length of this moment arm, the increase in the moment produced by compression of the control spring is offset, resulting in a substantially constant output pressure in the regulated operating range of the pump. The inclination further results in a reduction in the amount by which the control spring is compressed when the control ring moves from the first position to the second position. This reduction in the change in length of the control spring results in a corresponding reduction in the amount by which the spring force exerted by the control spring increases as the control ring moves from the first position to the second position.

Dependencies are inferred from the claim text.