Soft opening 2-way valve arrangement for a shock absorber

1. A valve arrangement for a shock absorber, said valve arrangement comprising:

a valve housing comprising a first and a second port;

a pilot chamber being in fluid communication with said first and/or second port, wherein a pilot pressure is defined by a hydraulic pressure in said pilot chamber; and

a main valve member being axially movably arranged in said valve housing and being arranged to interact with a main valve seat member in order to restrict a main fluid flow between said first and second ports in response to said pilot pressure acting on said main valve member;

wherein

the main valve seat member is movable between a first compression stroke position and a second rebound stroke position so that, during the compression stroke, the main fluid flow is restricted at a first restriction and a cooperating serially arranged second restriction, and, during the rebound stroke, the main fluid flow is restricted at a third restriction,

an orifice of said first restriction and an orifice of the second restriction is controlled by the axial position of the main valve member relative the valve housing and wherein

at least one of said valve housing and said movable main valve seat member further comprises a geometrically defined circumferential aperture having a radial inner wall and a radial outer wall, wherein the radial inner wall forms a part of the first restriction and the radial outer wall forms a part of the second restriction.

2. The valve arrangement according to claim 1 , wherein the first restriction is arranged upstream relative the second restriction, in view of the compression fluid flow direction.

3. The valve arrangement according to claim 1 , wherein the first restriction has a smaller orifice than the second restriction's orifice when being at least partly opened.

4. The valve arrangement according to claim 1 , wherein at least one of the first restriction and the second restriction is closed when said main valve seat member is in said rebound stroke position.

5. The valve arrangement according to claim 1 , wherein the third restriction is closed when said main valve seat member is in said compression stroke position.

6. The valve arrangement according to claim 1 , wherein the orifice of said third restriction is also controlled by the axial position of the main valve member relative the valve housing.

7. The valve arrangement according to claim 1 , comprising a fourth restriction being arranged in series with the second restriction.

8. The valve arrangement according to claim 7 , wherein the fourth restriction has a constant orifice being independent of the axial position of the main valve member relative the valve housing.

9. The valve arrangement according to claim 1 , wherein said circumferential aperture is formed in said valve housing and the movable valve seat member is sized and adapted to cooperate with the radial inner wall and radial outer wall of said circumferential aperture to form the first restriction and second restriction, so as to restrict the main fluid flow during the compression stroke.

10. The valve arrangement according to claim 9 , wherein the movable valve seat member is a washer or shim.

11. The valve arrangement according to claim 1 , wherein the movable valve seat member is a washer or shim closing an upper portion of said circumferential aperture during the rebound stroke.

12. The valve arrangement according to claim 1 , wherein the movable valve seat member is a washer or shim comprising at least three radial steering projections meshing with said main valve housing.

13. The valve arrangement according to claim 12 , wherein the space between said at least three steering radial projections in said washer or shim forms intermediate ports for allowing the main fluid flow during the compression stroke.

14. The valve arrangement according to claim 1 , further comprising a control valve member being movable in an axial direction relative said main valve member in response to an actuating force acting on said control valve member, said control valve member being resiliently loaded in an opposite direction to said actuating force by means of a biasing member, and wherein an interface between said control valve member and said main valve member comprises an opening restricting a bleed flow of the damping medium between the first and second port.

15. A valve arrangement for a shock absorber, said valve arrangement comprising:

a valve housing comprising a first and a second port˜

a pilot chamber being in fluid communication with said first and/or second port, wherein a pilot pressure is defined by a hydraulic pressure in said pilot chamber; and

a main valve member being axially movably arranged in said valve housing and being arranged to interact with a main valve seat member in order to restrict a main fluid flow between said first and second ports in response to said pilot pressure acting on said main valve member;

wherein

the main valve seat member is movable between a first compression stroke position and a second rebound stroke position so that, during the compression stroke, the main fluid flow is restricted at a first restriction and a cooperating serially arranged second restriction, and, during the rebound stroke, the main fluid flow is restricted at a third restriction, and wherein at least one of said valve housing and said movable main valve seat member further comprises a geometrically defined circumferential aperture having a radial inner wall and a radial outer wall, wherein the radial inner wall forms a part of the first restriction and the radial outer wall forms a part of the second restriction, and

wherein

said circumferential aperture is formed in said valve housing and the movable valve seat member is sized and adapted to cooperate with the radial inner wall and radial outer wall of said circumferential aperture to form the first restriction and second restriction, so as to restrict the main fluid flow during the compression stroke.

16. A valve arrangement for a shock absorber, said valve arrangement comprising:

a valve housing comprising a first and a second port;

a pilot chamber being in fluid communication with said first and/or second port, wherein a pilot pressure is defined by a hydraulic pressure in said pilot chamber; and

a main valve member being axially movably arranged in said valve housing and being arranged to interact with a main valve seat member in order to restrict a main fluid flow between said first and second ports in response to said pilot pressure acting on said main valve member;

wherein

the main valve seat member is movable between a first compression stroke position and a second rebound stroke position so that, during the compression stroke, the main fluid flow is restricted at a first restriction and a cooperating serially arranged second restriction, and, during the rebound stroke, the main fluid flow is restricted at a third restriction, and wherein at least one of said valve housing and said movable main valve seat member further comprises a geometrically defined circumferential aperture having a radial inner wall and a radial outer wall, wherein the radial inner wall forms a part of the first restriction and the radial outer wall forms a part of the second restriction, and wherein

the movable valve seat member is a washer or shim closing an upper portion of said circumferential aperture during the rebound stroke.