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. 07, 2000
Filed:
Nov. 13, 1998
Ken Yamamoto, Shizuoka, JP;
Takashi Nozaki, Shizuoka, JP;
NTN Corporation, Osaka, JP;
Abstract
A direct valve drive device which can open and lose a valve with accuracy even if a negative valve clearance forms between the cam and the valve stem due to a difference in thermal expansion coefficient between the cylinder head made of aluminum alloy and the iron valve. A valve lifter is mounted between the cam and the valve stem being biased toward the cam by a valve spring. An adjuster bolt is threaded into a threaded hole formed in the valve lifter. The force of a spring is applied to the adjuster bolt so that the adjuster bolt move, while rotating, toward the valve stem. Formed between the threadedly engaging portions of the adjuster bolt and the threaded hole is an axial hole which is smaller than the height of a ramp formed on the cam but large enough to absorb any difference in thermal expansion between the cylinder head and the valve. Even if the valve clearance changes toward the negative side, the axial gap absorbs such a change, thus preventing the valve from being pushed by the base circle of the cam.