Patent ID: 6321706
Filing Date: 2001-11-27
Classification: F01L

Abstract:
In an internal combustion engine having a rotatable camshaft (112, 412) with an irregular shaped cam (114, 414) that is rotatable therewith, a valve assembly comprising:a valve (110, 410) having an enlarged end and an opposed end, said valve being reciprocable along a longitudinal central axis extending between the enlarged end and the opposed end, said valve being reciprocable between an open position of said enlarged end and a closed position of said enlarged end;a cam follower (116, 416) operatively associated with said opposed end of said valve, said cam follower being positioned to engage said irregularly shaped cam;resilient means (118, 418) for imposing a biasing force on said cam follower against said cam to urge said valve to the closed position of said enlarged end;non-mechanical force means (122, 422) for acting on said valve, against the biasing force imposed by said resilient means, for delaying the movement of said valve from the open position of the enlarged end to the closed position of the enlarged end;wherein said non-mechanical force means comprises means (122, 422) for imposing an hydraulic force on said valve; andmeans (124, 422) for selectively controlling the application of force by said non-mechanical force means to vary the time involved in the movement of the valve from the open position of the enlarged end to the closed position of the enlarged end; andwherein the valve has an elongate stem (110d, 410d) extending between said enlarged end (110b, 410b) and said opposed end (110a, 410a) and an enlarged portion (110c, 410c) positioned on the elongate stem between said enlarged end and said opposed end, and wherein said means for selectively controlling the application of force by said non-mechanical force means comprises:a housing (122, 422) surrounding a portion of said valve stem, said enlarged portion being positioned within said housing, travel of said enlarged portion of said valve stem being entirely within said housing at all times during travel of said valve between the closed position of said enlarged end and the open position of said enlarged end; andwherein said means for selectively controlling comprises means 124, 424) for selectively introducing an hydraulic fluid into said housing and for withdrawing hydraulic fluid from said housing.