| 摘要 |
<p>A variable volume pump for satisfying the requirements of a hydraulic system while limiting fluid flow when the full volume of fluid displacement from the pump is not required by the hydraulic system. The pump includes one or more lines of reciprocable pumping pistons mounted radially around a crankshaft. The rotation of the crankshaft results in centrifugal flow of fluid through crankpin apertures for filling the pumping pistons. Each pumping piston reciprocates within a pumping chamber and the fluid volume filling the piston is directed through a discharge port to the hydraulic system. A valve piston is mounted within the pumping chamber in spaced apart opposing relationship to the pumping piston. The valve piston is normally scated against a valve seat when the pressure level in the hydraulic system is below that necessary to reduce flow. When the pressure in the hydraulic system reaches a predetermined level, compensating pressure is communicated against the valve piston which results in the movement of the valve piston towards the pumping piston. At a maximum desired system pressure, the valve piston contacts the pumping piston and follows the pumping piston during its suction stroke thereby limiting or blocking the fluid flow out the discharge port. Thus, the fluid flowfrom the pump is reduced in proportion to increased system pressure until a maximum desired output pressure is reached with minimum fluid flow.</p> |
