Control valve for a device for variably adjusting the control times of gas-exchange valves of an internal combustion engine

1. A control valve for a device for variably adjusting control times of gas-exchange valves of an internal combustion engine, comprising:

a substantially hollow cylindrical valve housing;

a non-return valve arranged within the substantially hollow cylindrical valve housing having a closing body and a spring element; and

an annular filter arranged within the substantially hollow cylindrical valve housing,

wherein the closing body is arranged radially within the annular filter so as to be movable in an axial direction of the annular filter, and the annular filter has guide surfaces which serve to guide movement of the closing body in the axial direction.

2. The control valve as claimed in claim 1 , wherein the annular filter has a valve seat for the closing body is formed on the annular filter.

3. The control valve as claimed in claim 1 , wherein the annular filter has a frame with two annular sections and struts with the guide surfaces being formed on the struts and the struts connecting the annular sections to one another.

4. The control valve as claimed in claim 1 , wherein the closing body is a ball, a cylinder or a conical section.

5. The control valve as claimed in claim 1 , wherein the substantially hollow cylindrical valve housing has a cavity which is stepped such that a step of the cavity serves as an axial stop for the annular filter.

6. The control valve as claimed in claim 1 , wherein the substantially hollow cylindrical valve housing has a cavity which is stepped such that a step of the cavity serves as valve seat for the closing body.

7. The control valve as claimed in claim 1 , wherein the substantially hollow cylindrical valve housing has a cavity which is stepped such that a step of the cavity serves as an axial stop for the annular filter and as a valve seat for the closing body.