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:
Feb. 29, 2000
Filed:
May. 28, 1998
Norio Takakura, Hokkaido, JP;
Dynac Corporation, Hokkaido, JP;
Abstract
An advantage of the present invention is the provision of a friction material having a porous structure and a large static coefficient of friction, that is made to have a porous structure so as to improve heat resistance but which does not exhibit time-varying characteristics in friction at the beginning of engagement. A friction material 120 is provided on the surface thereof with small holes 160 each of which is 0.02 mm.sup.2 to 0.2 mm.sup.2 in size and whose area ratio to the whole surface area of the friction material 120 is not less than 5% and whose ratio of depth to the thickness of the friction material 120 is not less than 20% and holds oil in the small holes 160. Even if the friction material 120 is made to have a porous structure, an oil film is always formed on a friction sliding surface by the oil held in the small holes 160 to reduce a shearing force produced when an associated plate shears the oil film, thereby preventing an increase in the dynamic coefficient of friction, which can prevent a speed change shock.