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:
May. 02, 2006
Filed:
Oct. 27, 2003
Hisashi Hayakawa, Shizuoka, JP;
Satoshi Kitano, Shizuoka, JP;
Tomoyoshi Izutsu, Shizuoka, JP;
Kazuo Komori, Shizuoka, JP;
Hisashi Hayakawa, Shizuoka, JP;
Satoshi Kitano, Shizuoka, JP;
Tomoyoshi Izutsu, Shizuoka, JP;
Kazuo Komori, Shizuoka, JP;
NTN Corporation, Osaka, JP;
Abstract
A hydraulic tensioner includes a cylinder having a hollow space filled with hydraulic oil. A plunger is slidably mounted in the cylinder. A pushrod is mounted in the hollow space so as to be axially movable together with the plunger with one end thereof protruding from the cylinder. A spring is mounted in the cylinder to bias the plunger and pushrod outwardly of the cylinder. The plunger is formed with a passage through which a pressure chamber and reservoir chamber communicate with each other. The passage is formed with a valve seat. A check ball is arranged so as to be moved into and out of contact with the valve seat. The check ball is adapted to contact the valve seat when pressure in the pressure chamber exceeds pressure in the reservoir chamber, thereby closing the passage. The valve seat is formed of a steel for carburizing and has a surface carbon concentration of 0.55–0.75% to reduce deposition of carbides and to have a surface hardness at least equal to that of the check ball.