Valve for opening and closing a line system

1. A valve, comprising:

a valve body with a longitudinal axis and that forms a valve seat;

a line system with a supply line for supplying a fluid to the valve seat and a discharge line for removing the fluid from the valve seat, wherein the fluid in the supply line stands under a supply pressure (pV) and in the discharge line under a working pressure (pN);

a closing element which cooperates with the valve seat for opening and closing the line system, wherein the closing element frees a throttle cross section between the valve seat and the closing element;

a restoring element which supplies a restoring force onto the closing element wherein the restoring force presses the closing element against the valve seat to close the line system;

a pressure chamber in which the fluid stands under a closing pressure with which the fluid applies a closing force onto the closing element for closing the line system;

wherein the valve comprises a conduit via which the closing pressure (pS) can be lowered in the pressure chamber below the supply pressure (pV) as a function of the freed throttle cross section;

wherein the conduit runs through the closing element and empties into the supply line, and wherein the conduit has a fluid communication with the pressure chamber;

a bypass which comprises the conduit and an annular slot surrounding the closing element and emptying into the discharge line; and

an insertion element which forms, together with the closing element, at least a part of the conduit in an area of the throttle cross section.

2. The valve according to claim 1 , wherein the closing element comprises a cylindrical recess in which the insertion element is arranged.

3. The valve according to claim 2 , wherein the insertion element has a U-shaped cross section with a first shank running substantially vertically to the longitudinal axis and a second shank running substantially parallel to the longitudinal axis.

4. The valve according to claim 3 , wherein the insertion element has a first front surface which faces the closing element and on which a number of indentations are arranged.

5. The valve according to claim 3 , wherein the insertion element on the free end of the second shank forms a second front surface which has a bevel facing the longitudinal axis.

6. The valve according to claim 5 , wherein the insertion element can be moved relative to the closing element.

7. The valve according to claim 6 , wherein the insertion element is fastened by a number of springs on the closing element.

8. The valve according to claim 1 , further comprising an adjusting device for moving the closing element along the longitudinal axis.

9. The valve according to claim 1 , wherein the restoring element is designed as a permanent magnet.

10. A vehicle comprising a valve according to claim 1 .

11. A method for operating a valve comprising:

providing a valve comprising:

a valve body with a longitudinal axis and that forms a valve seat;

a line system with a supply line for supplying a fluid to the valve seat and a discharge line for removing the fluid from the valve seat, wherein the fluid in the supply line stands under a supply pressure and in the discharge line under a working pressure;

a closing element which cooperates with the valve seat for opening and closing the line system, wherein the closing element frees a throttle cross section between the valve seat and the closing element;

a restoring element which supplies a restoring force onto the closing element, wherein the restoring force presses the closing element against the valve seat to close the line system;

a pressure chamber in which the fluid stands under a closing pressure with which the fluid applies a closing force onto the closing element for closing the line system; and

wherein the valve comprises a conduit via which the closing pressure can be lowered in the pressure chamber below the supply pressure as a function of the freed throttle cross section;

wherein the conduit runs through the closing element and empties into the supply line, and wherein the conduit has a fluid communication with the pressure chamber;

a bypass which comprises the conduit and an annular slot surrounding the closing element and emptying into the discharge line;

an insertion element which forms, together with the closing element, at least a part of the conduit in an area of the throttle cross section; and

freeing a throttle cross section between the valve seat and the closing element when the supply pressure (pV) exceeds a settable threshold value, and lowering the closing pressure (pS) in the pressure chamber below the supply pressure (pV) via the conduit.