Patent ID: 6425748
Filing Date: 2002-07-30
Classification: F04C

Abstract:
A positive displacement rotary pump comprising:a housing having an internal chamber, an inlet port in the housing intersecting the internal chamber having a downstream end and connected to a source of fluid at low pressure, a discharge port in the housing intersecting the internal chamber having an upstream end and connected to a fluid system, a sealing land on the housing separating the downstream end of the inlet port from the upstream end of the discharge port, a rotating group in the internal chamber defining a plurality of pump chambers which during rotation of the rotating group and at regular intervals traverse in succession the inlet port and the sealing land and the discharge port and which are sealed closed in the sealing land during traverse thereof so that a high fluid pressure develops in the discharge port and in the fluid system, a pre-charging passage means operable to establish fluid communication between the discharge port and a selected one of the plurality of pump chambers while the selected one of the plurality of pump chambers is sealed closed in the sealing land thereby to increase the fluid pressure in the selected one of the plurality of pump chambers to the high fluid pressure prevailing in the discharge port before the selected one of the plurality of pump chambers overlaps the upstream end of the discharge port, wherein the pre-charging passage means comprises: a stationary pre-charging passage on the housing communicating with the discharge port and terminating at a closed end in the angular interval defined by the sealing land remote from the ones of the pump chambers sealed closed in the sealing land, and a rotating pre-charging passage on the rotating group communicating with the selected one of the plurality of pump chambers and terminating at a closed end and overlapping the stationary pre-charging passage while the selected one of the plurality of pump chambers is sealed closed in the sealing land.