Valve part of a hydraulic control valve

1. Valve part of a control valve for controlling flows of pressurized medium, comprising:

a cylindrical valve housing with a valve housing hollow space that is open on one side in an axial direction, the valve housing is provided with a radial first work connection, a radial second work connection, and a radial pressure connection, each of which open into the valve housing hollow space,

a cylindrical control piston is held in the valve housing hollow space so that it can move in the axial direction and includes a control piston hollow space that is open on one side at an axial control piston hollow space opening, and at an opposite side the control piston includes a closed axial end face adapted to be acted upon by an actuator, and the control piston is provided with radial boreholes that are moveable into communication with the first and second radial work connections, and a radial discharge connection opening adjacent to the closed axial end face that opens into the control piston hollow space,

the control piston is constructed such that the work connections can be connected selectively in a fluid conducting way to the pressure connection and the discharge connection via the radial boreholes through axial displacement of the control piston, and

a cover is attached to the axial control piston hollow space opening, the cover having a plurality of cover openings, which are arranged adjacent to a cover edge, and the cover having a solid center area that is adapted to be contacted by a flow of pressure medium into the control piston hollow space through the radial boreholes to prevent a resulting reaction force on the control piston.

2. Valve part according to claim 1 , wherein the cover has a round shape and the cover openings are arranged distributed uniformly around the cover edge.

3. Valve part according to claim 1 , wherein the at least one cover opening has a circular hole-shaped construction.

4. Valve part according to claim 1 , wherein the at least one cover opening has an elongated hole-shaped construction.

5. Valve part according to claim 1 , wherein the at least one cover opening is constructed as a recess machined into a cover edge.

6. Valve part according to claim 1 , wherein the cover is attached to the control piston with a press fit, catch or snap-on mechanism.

7. Valve part according to claim 1 , wherein the cover is pressed against the control piston by a spring force of a compression spring applying a load on the control piston against an adjustment element of the actuator.

8. Control valve comprising an actuator and a valve part, the valve part including a cylindrical valve housing with a valve housing hollow space that is open on one side in an axial direction, the valve housing is provided with a radial first work connection, a radial second work connection, and a radial pressure connection, each of which open into the valve housing hollow space,

a cylindrical control piston is held in the valve housing hollow space so that the control piston can move in the axial direction and includes a control piston hollow space that is open on one side at an axial control piston hollow space opening, and at an opposite side the control piston includes a closed axial end face adapted to be acted upon by an actuator, and the control piston is provided with radial boreholes that are moveable into communication with the first and second radial work connections, and a radial discharge connection opening adjacent to the closed axial end face that opens into the control piston hollow space,

the control piston is constructed such that the work connections can be connected selectively in a fluid conducting way to the pressure connection and the discharge connection via the radial boreholes through axial displacement of the control piston, and

a cover is attached to the axial control piston hollow space opening, the cover having a plurality of cover openings, which are arranged adjacent to a cover edge, and the cover having a solid center area that is adapted to be contacted by a flow of pressure medium into the control piston hollow space through the radial boreholes to prevent a resulting reaction force on the control piston.

9. Camshaft adjuster comprising a control valve, the control valve including an actuator and a valve part, the valve part including a cylindrical valve housing with a valve housing hollow space that is open on one side in an axial direction, the valve housing is provided with a radial first work connection, a radial second work connection, and a radial pressure connection, each of which open into the valve housing hollow space,

a cylindrical control piston is held in the valve housing hollow space so that the control piston can move in the axial direction and includes a control piston hollow space that is open on one side at an axial control piston hollow space opening, and at an opposite side the control piston includes a closed axial end face adapted to be acted upon by an actuator, and the control piston is provided with radial boreholes that are moveable into communication with the first and second radial work connections, and a radial discharge connection opening adjacent to the closed axial end face that opens into the control piston hollow space,

the control piston is constructed such that the work connections can be connected selectively in a fluid conducting way to the pressure connection and the discharge connection via the radial boreholes through axial displacement of the control piston, and

a cover is attached to the axial control piston hollow space opening, the cover having a plurality of cover openings, which are arranged adjacent to a cover edge, and the cover having a solid center area that is adapted to be contacted by a flow of pressure medium into the control piston hollow space through the radial boreholes to prevent a resulting reaction force on the control piston.