Damper with volume reducing insert
View Patent ↗A shock absorber including a pressure tube, a piston assembly slidably disposed within the pressure tube, and a fluid transfer tube that extends about the pressure tube is provided. The piston assembly divides an inner volume of the pressure tube into first and second working chambers. An intermediate chamber between the pressure tube and the fluid transfer tube is arranged in fluid communication with the first working chamber. A valve assembly is disposed in fluid communication with the intermediate chamber and the second working chamber. The valve assembly controls fluid flow between the intermediate chamber and the second working chamber. At least part of the intermediate chamber is formed by a fluid transfer channel that extends longitudinally within the fluid transfer tube to provide a fluid flow path extending between the first working chamber and the valve assembly.
1. A shock absorber comprising:
a pressure tube extending about a longitudinal axis and defining an inner volume;
a piston assembly attached to a piston rod and slidably disposed within the pressure tube, the piston assembly dividing the inner volume of the pressure tube into a first working chamber and a second working chamber;
a bi-directional primary fluid flow path extending through the piston to fluidly interconnect the first working chamber and the second working chamber;
a fluid transfer tube extending about the pressure tube such that an intermediate chamber is defined between the pressure tube and the fluid transfer tube, the intermediate chamber disposed in fluid communication with the first working chamber;
a valve assembly disposed in fluid communication with and controlling fluid flow between the intermediate chamber and the second working chamber, wherein at least part of the intermediate chamber is formed by a fluid transfer channel that extends longitudinally within the fluid transfer tube to provide a secondary fluid flow path extending between the first working chamber and the valve assembly, wherein the primary fluid flow path extends in parallel with the secondary fluid flow path;
a reserve tube extending about the fluid transfer tube such that a reservoir chamber is defined between the fluid transfer tube and the reserve tube, wherein the pressure tube includes at least one outlet providing fluid communication between the first working chamber and the intermediate chamber, and wherein the valve assembly includes a reservoir valve disposed in fluid communication between the intermediate chamber and the reservoir chamber and a base valve disposed in fluid communication between the reservoir chamber and the second working chamber, the reservoir valve being positioned outside of the fluid transfer tube; and
an insert positioned in the intermediate chamber that reduces the volume of the intermediate chamber and defines the fluid transfer channel,
wherein the insert is shaped as a fixed, rigid split tube having first and second longitudinal edges that are spaced apart by a separation, the fluid transfer channel formed by the separation in the insert.
2. The shock absorber of claim 1 , wherein the fluid transfer tube includes at least one alignment projection that extends inwardly into said intermediate chamber and is received in the fluid transfer channel defined by the insert to insure proper alignment of the insert in the intermediate chamber and to prevent rotation of the insert relative to the fluid transfer tube.
3. The shock absorber of claim 1 , wherein the insert includes an inner surface facing the pressure tube, an outer surface facing the fluid transfer tube, and an insert wall thickness, the outer surface of the insert including a longitudinal groove where the insert wall thickness is reduced relative to an adjacent portion of the insert, the fluid transfer channel defined by the longitudinal groove in the insert.
4. The shock absorber of claim 1 , wherein the fluid transfer tube includes an inside surface facing the pressure tube, an outside surface, and a longitudinally extending pocket that protrudes from the outside surface of the fluid transfer tube, the fluid transfer channel extending within the longitudinally extending pocket of the fluid transfer tube.
5. The shock absorber of claim 1 , wherein the fluid transfer tube includes an inside surface facing the pressure tube, an outside surface, and a transfer tube wall thickness, the inside surface of the fluid transfer tube including a longitudinally extending groove where the transfer tube wall thickness is reduced relative to an adjacent portion of the transfer tube, wherein the fluid transfer channel is formed by the longitudinally extending groove in the fluid transfer tube.
6. The shock absorber of claim 1 , wherein the fluid transfer channel runs parallel to the longitudinal axis and has a limited circumferential extent of less than 180 degrees.
7. The shock absorber of claim 1 , wherein the insert defines only one fluid transfer channel in the intermediate chamber.
8. A shock absorber comprising:
a pressure tube extending about a longitudinal axis and defining an inner volume;
a piston assembly attached to a piston rod and slidably disposed within the pressure tube, the piston assembly dividing the inner volume of the pressure tube into a first working chamber and a second working chamber;
a bi-directional valve positioned within the piston assembly to control fluid flow from the first working chamber to the second working chamber as well as from the second working chamber to the first working chamber;
a fluid transfer tube extending about the pressure tube such that an intermediate chamber is defined between the pressure tube and the fluid transfer tube, the intermediate chamber disposed in fluid communication with the first working chamber; the fluid transfer tube including a port radially extending through a wall of the fluid transfer tube to interconnect the intermediate chamber and the reservoir chamber;
a reserve tube extending about the fluid transfer tube such that a reservoir chamber is defined between the fluid transfer tube and the reserve tube;
a base valve disposed in fluid communication with and controlling fluid flow between the reservoir chamber and the second working chamber,
wherein at least part of the intermediate chamber is formed by a fluid transfer channel that extends longitudinally within the fluid transfer tube to provide a fluid flow path extending between the first working chamber and the reservoir chamber that bypasses the base valve and the second working chamber; and
an insert positioned in the intermediate chamber that is shaped as a fixed, rigid split tube, the insert including an inner surface abutting the pressure tube, an outer surface abutting the fluid transfer tube, and first and second longitudinal edges that are spaced apart by a separation, wherein the fluid transfer channel is formed by the separation in the insert.
9. The shock absorber of claim 8 , wherein the fluid transfer tube includes an inside surface abutting the pressure tube, an outside surface, and a longitudinally extending pocket that protrudes from the outside surface of the fluid transfer tube, the fluid transfer channel extending within the longitudinally extending pocket of the fluid transfer tube.
10. The shock absorber of claim 8 , wherein the fluid transfer tube includes a flattened area on an outer surface circumscribing the port.