High-pressure cleaning apparatus

A high-pressure cleaning apparatus comprising:

• a high-pressure pump, the pump comprising a pump inlet for connecting a supply conduit to supply a liquid, and a pump outlet;
• a high-pressure line connected to the pump outlet;
• an operating unit comprising a high-pressure gun connected to the high-pressure line;
• a drive unit;
• a control unit coupled to the drive unit;
• a pressure sensor coupled to the control unit;
• the pump comprising:
• a suction chamber;
• at least one pump chamber which is arranged downstream of the suction chamber and in which liquid is pressurized;
• a pressure chamber arranged downstream of the pump chamber, with a pressure valve being interposed between the pump chamber and the pressure chamber, the pressure chamber having a first chamber region and a second chamber region downstream thereof, a non-return valve being disposed between the first chamber region and the second chamber region;
• a return line via which the first chamber region of the pressure chamber is in flow communication with the suction chamber;
• and
• a valve unit by which a free cross-sectional area of the return line is changeable, the drive unit being associated with the valve unit;
• wherein:
• a liquid pressure is detectable on the pressure side of the pump chamber by the pressure sensor, and depending on the signal of the pressure sensor, the liquid pressure is controllable to a predetermined or predeterminable liquid pressure by changing of the free cross-sectional area of the return line,
• the high-pressure pump comprises, downstream of the valve unit, at or in the return line, an additional pressure valve which opens the return line when a threshold pressure is exceeded, the additional pressure valve sealingly closing the return line below the threshold pressure, and
• the valve unit comprises a valve body receiving part partially forming the return line and comprises a valve body of the valve unit received therein, and wherein the additional pressure valve is configured as a valve ring surrounding the valve body receiving part.