Magnetorheological fluid

Patent metadata

Field	Value
Publication number	US-11879519-B2
Application number	US-202217726555-A
Country	US
Kind code	B2
Filing date	Apr 22, 2022
Priority date	Apr 22, 2022
Publication date	Jan 23, 2024
Grant date	Jan 23, 2024

Abstract

A magnetorheological fluid with balanced viscosity and sedimentation properties includes: a magnetic material; a medium to allow the magnetic material to be dispersed therein; a dispersant to disperse the magnetic material within the medium while forming a magnetic material holding structure to hold the magnetic material; and a reinforcing agent to reinforce the magnetic material holding structure. An amount of the magnetic material is 25 wt % to 75 wt % relative to a sum of the medium and the magnetic material. An amount of the medium is 25 wt % to 75 wt % relative to the sum of the medium and the magnetic material. An amount of the dispersant is 0.5 wt % to 6 wt % relative to the sum of the medium and the magnetic material. An amount of the reinforcing agent is 5 wt % to 300 wt % relative to a weight of the dispersant.

First claim

What is claimed is:

1. A magnetorheological fluid comprising:
a magnetic material;
a medium to allow the magnetic material to be dispersed therein;
a dispersant to disperse the magnetic material within the medium while forming a magnetic material holding structure to hold the magnetic material; and
a reinforcing agent to reinforce the magnetic material holding structure, wherein
an amount of the magnetic material is 25 wt % to 75 wt % relative to a sum of the medium and the magnetic material,
an amount of the medium is 25 wt % to 75 wt % relative to the sum of the medium and the magnetic material,
an amount of the dispersant is 0.5 wt % to 6 wt % relative to the sum of the medium and the magnetic material, and
an amount of the reinforcing agent is 5 wt % to 300 wt % relative to a weight of the dispersant,
wherein the dispersant comprises a rheology control agent,
wherein the dispersant comprises silica,
wherein the magnetic material holding structure has a network structure, and
wherein the silica has a primary particle size of greater than 10 nm.

2. The magnetorheological fluid according to claim 1 , wherein the silica is wet-process silica.

3. The magnetorheological fluid according to claim 2 , wherein the wet-process silica has a secondary particle size of smaller than 2.5 μm.

4. The magnetorheological fluid according to claim 1 , wherein the reinforcing agent is selected from polyhydroxycarboxylic acid derivatives.

5. The magnetorheological fluid according to claim 4 , wherein the polyhydroxycarboxylic acid derivatives comprise polyhydroxycarboxylic acid amides or polyhydroxycarboxylic acid esters.

Assignees

• Yamashita Rubber Kk

Inventors

• Shimizu Hideyuki
• Koseki Taiki

Classifications

• F16F9/535 Primary

  Magnetorheological [MR] fluid dampers (springs comprising magnetorheological [MR] elastomers F16F1/361) · CPC title

• F16F2224/045

  magnetorheological · CPC title

• H01F1/447 Primary

  characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids (electrorheological fluids C10M171/001) · CPC title