Patent ID: 8439653

Claim:
Pump for a high-pressure cleaning apparatus for delivering a cleaning liquid, said pump comprising at least one pump chamber into which at least one reciprocally movable piston plunges and which is connected via at least one inlet valve to a suction conduit and is connected via at least one outlet valve to a pressure conduit, and a bypass conduit leading from the pressure conduit to the suction conduit and having arranged therein a bypass valve, a valve body of which is connected, via a piston rod, to a control member which displaces the valve body as a function of a flow rate of the cleaning liquid in the pressure conduit to a closed position or an open position and displaces a switch plunger which is coupled to the valve body to a first or a second switch position to actuate a switch element, wherein the valve body, as it transitions from its closed position to its open position, opens a passage upstream of a valve seat permitting cleaning liquid to flow therethrough, the passage having a first constant flow cross-section along a first partial distance of a stroke movement of the valve body, the flow cross-section of said passage becoming wider than the first constant flow cross-section when the valve body is at a predetermined distance from the valve seat.