The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 05, 2002
Filed:
Jun. 02, 1999
Shigeki Endo, Tokorozawa, JP;
Hiroaki Wada, Kawasaki, JP;
Bridgestone Corporation, Tokyo, JP;
Abstract
The present invention discloses an electrorheological fluid comprising: spherical carbonaceous particles obtained substantially from a solvent and a condensation product formed by a methylene type bonding of an aromatic sulfonic acid or a salt thereof as materials; and an, electric insulating oil. The electric insulating oil preferably has a relative dielectric constant of 3 or more and a kinematic viscosity at 25° C. of 1 to 100 mm /second. The electric insulating oil may be, for example, fluorosilicone oil, a mixture of fluorosilicone oil and silicone oil, or a mixture of dimethyl silicone oil and modified silicone oil. The electrorheological fluid of the present invention may further include modified silicone oil at a weight percentage of 0.01 to 5%. The electrorheological fluid of the present invention can be formed so as to have a dielectric breakdown strength of a predetermined value or more due to a production process in which the spherical carbonaceous particles and the electric insulating oil are mixed under a reduced pressure or a production process in which the spherical carbonaceous particles and the electric insulating oil are mixed under a normal pressure and thereafter, air or the like is removed from an obtained electrorheological fluid under a reduced pressure. The electrorheological fluid of the present invention preferably has a dielectric breakdown strength of 4.0 kV/mm or more.