Multi-Stage Pump Having Reverse Bypass Circuit

摘要

A multi-stage pump includes a pump head having at least two compression stages disposed in series With espect to the direction of flow of fluid through the pump, and a reverse fluid bypass circuit including a fluid passageway through which fluid flowing between upstream and downstream ones of the compression stages can he circulated back upstream of the upstream compression stage. The reverse fluid bypass circuit may restrict or stop the flow of fluid through the fluid passageway as long as the pressure differential across the fluid passage is below a. predetermined value. To this end, the reverse fluid bypass circuit may be configured to restrict the flow of fluid while the fluid is in its transitional or molecular flow regime, and allow the flow of fluid while the fluid is in its viscous flow regime.

主权项

1. A multi-stage pump comprising:
an inlet portion having a pump inlet and constituting a low pressure side of the pump where fluid is drawn into the pump, and an exhaust portion having a pump outlet and constituting a compression side where fluid is discharged from the pump at pressure greater than that of the fluid at the low pressure side; a pump head having an inlet opening to which the pump inlet extends, an exhaust opening leading to the pump outlet, at least two compression stages disposed in series with respect to the direction of flow of fluid through the pump, and a fluid bypass circuit, and wherein each of the compression stages has an ingress through which the fluid enters the stage and an egress through which the fluid exits the stage, a flow path along which fluid flows from the pump inlet to the pump outlet extends in the pump between the pump inlet and an upstream one of the compression stages, between the egress of the upstream one of the compression stages and the ingress of a downstream one of the compression stages, and between the egress of the downstream one of the compression stages and the pump outlet, and the fluid bypass circuit defines a fluid passageway discrete from the flow path and connected to the flow path at a first location between the egress of one of the compression stages and the ingress of the next compression stage downstream therefrom and at a second location upstream of the ingress of said one of the compression stages.