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:
Dec. 13, 1983
Filed:
Aug. 26, 1981
Alexander Goloff, East Peoria, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
A varible rate spring for use in a combustion engine has a lower spring rate at high valve lifts than at low valve lifts to reduce contact stresses in the valve train assembly (24) at maximum valve lift. In one embodiment, the varible rate spring includes a cantilevered spring (70) having a free end (80) for engagement with a valve (12), a fixed end secured to a cylinder head (18) and an intermediate portion (88) which engages a pair of stops (90/92). As the valve moves between the seated position to an intermediate lift position only that portion of the spring (70), from its free end (80) to the intermediate portion (88) engaging the stops (90/92) is active. At the intermediate lift position the spring (70) disengages the stops (90/92) and the entire length of the spring (70) becomes active thereby decreasing the spring rate. In another embodiment two coil springs (94/96) are connected in series having a separator (110), which acts as a spring damper, disposed therebetween. The separator (110) engages a spring retainer (98) to preload the lower spring. Only the upper spring (96) is active as the valve (12) moves between the seated and intermediate lift position, the preload on the lower spring (96) being overcome at the intermediate lift position so that both springs (94/96) are active as the valve (12) moves to the maximum lift position.