Double tube damper with structural pressure tube

1. A twin tube shock absorber comprising:

a pressure tube defining a fluid chamber;

a piston assembly fixed to a piston rod and disposed within the fluid chamber, the piston assembly dividing the fluid chamber into an upper working chamber and a lower working chamber;

a lower mount;

a rod guide assembly;

the pressure tube extending between the lower mount and the rod guide assembly and being in load bearing contact with both the lower mount and the rod guide assembly, so as to be fixed against movement relative to the lower mount and the rod guide assembly, and to act as a principal load bearing component for the shock absorber;

a reserve tube surrounding the pressure tube and being in contact with the lower mount, a reservoir chamber being defined between the reserve tube and the pressure tube;

a bumper cap attached directly to an outer surface of the reserve tube and including an aperture in receipt of the piston rod; and

a flexible sealing component positioned between the pressure tube and the reserve tube preventing a transfer of the load therebetween such that the bumper cap and reserve tube are isolated from the loads passing through the pressure tube, the flexible sealing component sealing the reservoir chamber; wherein a structural integrity of the pressure tube is greater than a structural integrity of the reserve tube, and the reserve tube operating to provide substantially no load bearing operation for the shock absorber.

2. The shock absorber according to claim 1 , wherein the pressure tube has a larger wall thickness than a wall thickness of the reserve tube.

3. The shock absorber according to claim 1 , wherein the pressure tube is manufactured from a different material than the reserve tube.

4. The shock absorber according to claim 1 , wherein the pressure tube is a metal pressure tube and the reserve tube is a plastic reserve tube.

5. The shock absorber according to claim 3 , wherein the reserve tube has a telescopic geometry and is operably secured to the lower mount.

6. The shock absorber according to claim 5 , wherein the telescopic geometry includes a bellows.

7. The shock absorber according to claim 1 , wherein the reserve tube has a telescopic geometry and is operably secured to the lower mount.

8. The shock absorber according to claim 7 , wherein the telescopic geometry includes a bellows.

9. The shock absorber according to claim 1 , further comprising a mount attached to one of the pressure tube and the piston assembly.

10. The shock absorber according to claim 9 , wherein the lower mount includes an insert for interfacing a distal end of the pressure tube to the lower mount in a manner enabling the pressure tube to act as the principal load bearing component of the shock absorber.

11. The shock absorber according to claim 10 , wherein the insert is welded to the distal end of the pressure tube and is further configured to help secure a valve assembly in place at the distal end of the pressure tube.

12. A method for forming a shock absorber, comprising:

using a pressure tube to define a fluid chamber;

arranging a piston assembly within said fluid chamber, the piston assembly dividing the fluid chamber into an upper working chamber and a lower working chamber; and

arranging a reserve tube to surround the pressure tube such that a reservoir chamber is defined between the reserve tube and the pressure tube;

forming the pressure tube from at least one of a material thickness or a material type to provide a first structural strength;

operably securing a distal end of the pressure tube to a lower mount;

forming the reserve tube from at least one of a material thickness or a material type to provide a second structural strength;

selecting the first and second structural strengths such that the second structural strength is less than the first structural strength;

spacing the reserve tube apart from the pressure tube such that the reserve tube provides substantially no load bearing operation for the shock absorber, and further securing the pressure tube such that the pressure tube provides a principal load bearing operation for the shock absorber; and

positioning a flexible sealing component between the pressure tube and the reserve tube to seal an end of the reserve tube and at least partially define a reservoir chamber between the pressure tube and the reserve tube.

13. The method of claim 12 , further comprising at least one of:

forming the pressure tube with a larger wall thickness than a wall thickness of the reserve tube; or

forming the pressure tube from metal and the reserve tube from a material providing a lesser structural strength than metal.

14. A shock absorber comprising:

a pressure tube defining a fluid chamber;

a piston assembly disposed within the fluid chamber, the piston assembly dividing the fluid chamber into an upper working chamber and a lower working chamber;

a lower mount to which a first end of the pressure tube is fixed;

a rod guide assembly to which a second end of the pressure tube is operably secured;

a bumper cap operably associated with the rod guide assembly;

a reserve tube surrounding the pressure tube and extending between the bumper cap and the lower mount, a reservoir chamber being defined between the reserve tube and said pressure tube;

a structural integrity of the pressure tube being greater than a structural integrity of the reserve tube; and

wherein the reserve tube includes a first end fixed to the lower mount and a second end fixed to the bumper cap, the reserve tube and the pressure tube each including second opposite ends that are spaced apart from one another to enable a degree of movement of the second end of the reserve tube relative to the second end of the pressure tube.