US 2003/0145820 A1 · Internal combustion engine provided with decompressing mechanism and method of adjusting valve lift for decompression

Abstract

A decompressing mechanism (D) for an internal combustion engine (E) is incorporated into a camshaft (15) provided with a bore (54) extending in the direction of the arrow (A) along the axis (L1) of rotation of the camshaft (15). The decompressing mechanism (D) includes a decompression member (80) formed by metal injection and integrally having a flyweight (81), a decompression cam (82) for exerting a valve-opening force through an exhaust rocker arm (48) on an exhaust valve, and an arm (83) connecting the flyweight (81) and the decompression cam (82). The flyweight (81) is supported for swing motion by a pin (71) on the camshaft (15). The axis (L2) of swing motion of the flyweight (81) is included in a plane (P4) substantially perpendicular to the axis (L1) of rotation, and does not intersect the axis (L1) of rotation and the bore (54) of the camshaft (15). The fully expanded decompression member (80) revolves in a cylindrical space of a small diameter around the camshaft (15).

Claims13

Dependent claims

An internal combustion engine comprising:

a crankshaft;
a camshaft driven for rotation about its axis of rotation in synchronism with the crankshaft;
a valve-operating cam mounted on the camshaft;
engine valves controlled for opening and closing by the valve-operating cam;
and a decompressing means for opening the engine valve during a compression stroke in a starting phase of the internal combustion engine;
wherein the camshaft is a hollow shaft having an axial bore extending along an axis of rotation thereof, the decompressing means includes a flyweight supported for swing motion by a holding part formed on the camshaft, and a decompression cam that operates together with the flyweight to exert a valve-opening force on the engine valve, an axis of swing motion of the flyweight is included in a plane substantially perpendicular to the axis of rotation, and does not intersect the axis of rotation and the bore of the camshaft.

3 more elements

A decompressing lift adjusting method of adjusting decompressing lifts respectively for a first internal combustion engine and a second internal combustion engine having different output characteristics, respectively, and respectively comprising fuel feed devices, camshafts, valve-operating cams formed on the camshafts, engine valves controlled for opening and closing by the valve-operating cams, starting devices, and decompressing means respectively provided with decompression cams capable of projecting radially outward from base circles including heels of the valve-operating cams to open the engine valves during a decompressing operation;

wherein the respective decompressing means of the first internal combustion engine and the second internal combustion engine are identical in characteristic quality, and diameter of the base circle including the heel of the valve-operating cam of the first internal combustion engine and that of the base circle including the heel of the valve-operating cam of the second internal combustion engine are different from each other.

Dependencies are inferred from the claim text.

Internal combustion engine provided with decompressing mechanism and method of adjusting valve lift for decompression

Life of this patent

Internal combustion engine provided with decompressing mechanism and method of adjusting valve lift for decompression

Life of this patent

Abstract

Claims13