Hydraulic suspension damper with a hydraulic stroke stop arrangement

1. A hydraulic damper, comprising

a tube filled with working liquid,

a main piston assembly disposed slidably inside the tube along an axis, dividing the tube into a rebound chamber and a compression chamber and provided with rebound and compression valve assemblies to control the flow of working liquid within the tube during rebound and compression stroke of the hydraulic damper, and

a piston rod attached to the main piston assembly and led outside the hydraulic damper through a sealed piston rod guide,

wherein at least one end of the tube is provided with an additional stroke stop arrangement comprising

a narrowed section of a diameter smaller than a diameter of the tube, having an inlet opening to the tube and provided at least partially with at least one axial groove having the cross-sectional area decreasing from the inlet along the narrowed section, and

an additional piston assembly having a diameter smaller than the diameter of the tube, displaceable along with the main piston assembly, and configured to be slidably disposed in the narrowed section to generate additional damping force,

wherein,

the additional piston assembly comprises:

a plastic ring guide fixed to the piston rod and distal with respect to the main piston assembly,

a ring having an annular gap guided by the ring guide and configured to make a sliding fit with an internal wall of the narrowed section of the tube, and

a retaining member fixed to the piston rod and proximal with respect to the main piston assembly,

wherein the ring surrounds an inner axial rim of the ring guide with radial clearance and is axially displaceable between the retaining member and a retaining surface of the ring guide,

wherein the inner axial rim defines at least one annular channel in fluid connection with at least one radial channel defined in the retaining surface,

and wherein the ring guide has at least one fixing protrusion extending radially inwardly toward the axis for engaging an annular slot in the piston rod and securing the ring guide to the piston rod,

wherein,

said at least one fixing protrusion is disposed at said inner axial rim of said ring guide and

said at least one fixing protrusion having a height that is larger than said radial clearance between said inner axial rim of said ring guide and said ring.

2. The hydraulic damper according to claim 1 , wherein said at least one fixing protrusion is disposed at the end of said inner axial rim of said ring guide proximal with respect to the main piston assembly.

3. The hydraulic damper according to claim 2 , wherein the at least one radial channel includes at least two radial channels defined in the retaining surface, and the at least two radial channels are fluidly connected about said inner axial rim.

4. The hydraulic damper according to claim 2 , wherein the at least one radial channel includes at least two radial channels, and the retaining surface defines an annular section between two of the at least two radial channels and having a width larger than the annular gap of the ring.

5. The hydraulic damper according to claim 2 , wherein said narrowed section of the tube has a form of an insert made of plastic.

6. The hydraulic damper according to claim 2 , wherein said stroke stop arrangement is a rebound stroke stop arrangement.

7. The hydraulic damper according to claim 2 , wherein said hydraulic damper is a twin-tube damper.

8. The hydraulic damper according to claim 1 , wherein the at least one radial channel includes at least two radial channels defined in the retaining surface, and the at least two radial channels are fluidly connected about said inner axial rim.

9. The hydraulic damper according to claim 3 , wherein the at least one radial channel includes at least two radial channels, and the retaining surface defines an annular section between the radial channels and having a width larger than the annular gap of the ring.

10. The hydraulic damper according to claim 8 , wherein said narrowed section of the tube has a form of an insert made of plastic.

11. The hydraulic damper according to claim 8 , wherein said stroke stop arrangement is a rebound stroke stop arrangement.

12. The hydraulic damper according to claim 8 , wherein said hydraulic damper is a twin-tube damper.

13. The hydraulic damper according to claim 1 , wherein the at least one radial channel includes at least two radial channels, and the retaining surface defines an annular section between two of the at least two radial channels and having a width larger than the annular gap of the ring.

14. The hydraulic damper according to claim 13 , wherein said stroke stop arrangement is a rebound stroke stop arrangement.

15. The hydraulic damper according to claim 13 , wherein said hydraulic damper is a twin-tube damper.

16. The hydraulic damper according to claim 1 , wherein said narrowed section of the tube has a form of an insert.

17. The hydraulic damper according to claim 16 , wherein the insert is made of plastic.

18. The hydraulic damper according to claim 1 , wherein said stroke stop arrangement is a rebound stroke stop arrangement.

19. The hydraulic damper according to claim 1 , wherein said hydraulic damper is a twin-tube damper.

20. The hydraulic damper according to claim 1 , wherein the hydraulic damper is a motor vehicle hydraulic suspension damper.