US 4,790,271 A · Auto-decompression system for engines

Abstract

A valve control device including a decompression cam. The decompression cam fits loosely on the camshaft adjacent to a valve motion cam. The decompression cam may be selectively moved and retained so as to extend beyond the valve motion cam to control the associated cam follower during the compression stroke. An eccentric weight is associated with the decompression cam so as to draw it from an extension beyond the valve motion cam under normal operating conditions. When starting, a spring biases the decompression cam outwardly so as to interlock the cam with a projection associated with the camshaft. When the projection retains the decompression cam outwardly against the cam follower, an associated engine valve is partially open to reduce compression during the compression stroke. Further rotation releases the decompression cam from the projection and allows the centrifugal force operating on the eccentric weight to draw the decompression cam out of operation for normal running. A reverse, decompression cam operates by means of a one-way clutch to lift the associated cam follower when the engine rotates partially in reverse. When rotating normally, the reverse, decompression cam is declutched from the camshaft and remains inoperative.

Claims14

Dependent claims

A valve control device for an engine having a combustion chamber, a valve controlling communication with said chamber, a camshaft rotatably mounted in said engine, a valve motion cam fixed to said camshaft for rotation therewith, and a valve actuation mechanism including a cam follower engageable with said valve motion cam, said valve control device comprising:

a decompression cam carried by said camshaft axially adjacent said valve motion cam, said decompression cam including a base circle portion defining an outer peripheral surface smaller in radial extent than the outer peripheral surface of said valve motion cam and having an inner bore to loosely encircle said camshaft;
means for adjusting the position of said decomposition cam with respect to said camshaft between two locations including a first location on which said outer peripheral surface of said decompression cam extends radially outwardly from the axis of said camshaft to an extent greater than that of said valve motion cam to engage said cam follower for decompression operation of said valve, and a second location at which said outer peripheral surface of said decompression cam extends radially outwardly from the axis of said camshaft to an extent less than that of said valve motion cam whereby said valve motion cam engages said cam follower for normal operation of said valve;
and
means responsive to the rotational speed of said camshaft for automatically moving said decompression cam between said first and second locations.

1 more element

Dependencies are inferred from the claim text.

Auto-decompression system for engines

Life of this patent

Auto-decompression system for engines

Life of this patent

Abstract

Claims14