Shock absorber including a hydraulic fluid having an improved flash point

Patent metadata

Field	Value
Publication number	US-12509640-B2
Application number	US-202318329968-A
Country	US
Kind code	B2
Filing date	Jun 6, 2023
Priority date	Jun 17, 2022
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

A shock absorber that includes a pressure tube that defines a working chamber having a hydraulic fluid located therein; a piston assembly positioned in the working chamber, and dividing the working chamber into an upper working chamber and a lower working chamber; and a piston rod engaged with the piston assembly that moves the piston assembly in the working chamber, wherein the hydraulic fluid includes a primary oil, a secondary oil, and an additive package, the secondary oil includes at least a gas-to-liquid oil in an amount that ranges between 4.0 wt % to 10.0 wt % relative to a total amount of the hydraulic fluid, and the hydraulic fluid includes a flash point of at least 174 degrees C.

First claim

What is claimed is:

1 . A shock absorber, comprising:
a pressure tube that defines a working chamber having a hydraulic fluid located therein; a piston assembly positioned in the working chamber, and dividing the working chamber into an upper working chamber and a lower working chamber; and a piston rod engaged with the piston assembly that moves the piston assembly in the working chamber, wherein the hydraulic fluid includes a primary oil, a secondary oil, and an additive package, the secondary oil includes at least a gas-to-liquid oil in an amount that ranges between 4.0 wt % to 10.0 wt % relative to a total amount of the hydraulic fluid, and the hydraulic fluid includes a flash point of at least 174 degrees C.

2 . The shock absorber according to claim 1 , wherein the primary oil includes one of a mineral lubricating base oil, a synthetic lubricating base oil, and a mixture of the mineral lubricating base oil and the synthetic lubricating base oil.

3 . The shock absorber according to claim 2 , wherein the mineral lubricating base oil is selected form the group consisting of a paraffinic mineral oil, a naphthenic mineral oil, and an aromatic mineral oil.

4 . The shock absorber according to claim 1 , wherein the primary oil is present in the hydraulic fluid in an amount that ranges between 70 wt % to 95 wt % relative to the total amount of the hydraulic fluid.

5 . The shock absorber according to claim 1 , wherein the additive package includes at least one selected from the group consisting of an antioxidant, an anti-wear additive, a viscosity modifier, a dispersant, a detergent, a corrosion inhibitor, a pour point additive, a pressure additive, an anti-friction lubricant, a dye that fluoresces when exposed to UV light, and an anti-foaming agent.

6 . The shock absorber according to claim 5 , wherein the additive package is present in the hydraulic fluid in an amount that ranges up to 20 wt % relative to the total amount of the hydraulic fluid.

7 . The shock absorber according to claim 1 , wherein the hydraulic fluid exhibits a viscosity index of 137.

8 . The shock absorber according to claim 1 , wherein the hydraulic fluid exhibits a pour point of at least −54 degrees C.

9 . The shock absorber according to claim 1 , wherein the hydraulic fluid exhibits an aniline point of at least 95.9 degrees C.

10 . The shock absorber according to claim 1 , wherein the hydraulic fluid exhibits a friction value of 2.9 N.

11 . The shock absorber according to claim 1 , wherein the hydraulic fluid exhibits a fire point of at least 181 degrees C.

12 . The shock absorber according to claim 1 , wherein the hydraulic fluid includes a sulfur content of 22 ppm or less.

Assignees

• Fed Mogul Motorparts Llc

Inventors

• Bender Michael
• Gaynier Nathan

Classifications

• F16F9/19

  with a single cylinder {and of single-tube type} · CPC title

• C10N2030/02

  Pour-point; Viscosity index · CPC title

• C10N2040/08

  Hydraulic fluids, e.g. brake-fluids · CPC title

• C10M2203/1045

  used as base material · CPC title

• C10M2203/1065

  used as base material · CPC title