Vane pump with substantially constant regulated output

摘要

A variable displacement vane pump provides a substantially constant output pressure in its regulated operation region. A longitudinal axis of the control spring is inclined, with respect to a plane through the rotational axis of a pivot and a contact point between the control ring and the control spring. The inclination reduces 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. The reduced length moment arm offsets the increase in the moment produced by compression of the control spring is offset to achieve a substantially constant output pressure. The control spring is compressed a reduced amount during pump operation to minimize the change in output force exerted by the control spring as the control ring moves between positions.