Variable rate valve spring

Details Variable rate valve spring Variable rate valve spring

1981-08-26

1983-12-13

Chambers, A. Michael

Valves and valve actuation

Biased valve

Springs and spring retainers

123 9065, 267158, F16F 100

Patent

active

044201419

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.

REFERENCES:
patent: 1840128 (1932-01-01), Pfeiffer
patent: 2117434 (1938-05-01), Krebs
patent: 2142224 (1939-01-01), Turlay
patent: 2821971 (1958-02-01), Benz et al.
patent: 3055350 (1962-09-01), Buchi
patent: 3195528 (1965-07-01), Franklin
patent: 3602205 (1971-08-01), Turkish
patent: 3612016 (1971-10-01), Jelen
patent: 3853101 (1974-12-01), Iskenderion et al.

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