Valve lift assembly for a cam-in-block engine

Abstract

An engine includes a block containing multiple valves, and a camshaft defining multiple cams for rotation about a camshaft axis. A valve lift assembly is operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis. The assembly includes a follower and a follower control mechanism. The follower is disposed in contact with the cam at a contact point that defines a contact path extending along a surface of the cam as the cam rotates about the camshaft axis. The follower is moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam. The follower control mechanism is operable to control the movement of the follower within the adjustment range.

What is claimed is: 
     
         1 . An engine including:
 a block;   a plurality of valves;   a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis; and   a plurality of valve lift assemblies, each valve lift assembly being mounted in the block and operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis; each valve lift assembly including:
 a follower, the follower being arranged in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis; the follower being moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and 
 a follower control mechanism operable to control the movement of the follower within the adjustment range. 
   
     
     
         2 . An engine according to  claim 1 , wherein the follower is moveable within the adjustment range between two extreme positions defining two contact point positions arranged symmetrically about an adjustment plane containing the camshaft axis, the lift axis lying within or parallel with the adjustment plane. 
     
     
         3 . An engine according to  claim 1 , wherein the follower control mechanism includes an actuator arranged to move the follower within the adjustment range. 
     
     
         4 . An engine according to  claim 3 , wherein the actuator is moveable in a direction parallel or collinear with the lift axis to move the follower within the adjustment range. 
     
     
         5 . An engine according to  claim 3 , wherein the actuator is moveable in a direction nonparallel with the lift axis to move the follower within the adjustment range. 
     
     
         6 . An engine according to  claim 3 , wherein the follower includes a guide element slidably engaged with first and second, mutually inclined guide surfaces of the follower control mechanism, the actuator being operable to move the first guide surface relative to the second guide surface. 
     
     
         7 . An engine according to  claim 3 , wherein the follower includes a roller and a carrier, the roller being mounted for rotation on the carrier, the carrier being moveable by the actuator. 
     
     
         8 . An engine according to  claim 7 , wherein the carrier comprises an arm pivotably mounted on an axle and extending in collinear or parallel relation with the lift axis. 
     
     
         9 . An engine according to  claim 1 , wherein the follower control mechanism is arranged to provide infinite adjustment of the follower within the adjustment range. 
     
     
         10 . An engine according to  claim 1 , wherein the follower control mechanism is arranged to releasably restrain the follower at a selected position within the adjustment range. 
     
     
         11 . An engine according to  claim 1 , wherein the follower control mechanism is arranged to move the follower to a selected position within the adjustment range and to releasably restrain the follower in the selected position. 
     
     
         12 . An engine according to  claim 1 , wherein the follower control mechanism includes:
 first and second components, the first component being operatively associated with the follower and moveable relative to the second component by movement of the follower within the adjustment range; and   at least one detent actuator mechanism, the detent actuator mechanism including a detent, the detent being moveable by the detent actuator mechanism between an engaged position in which the detent is arranged to inhibit relative movement between the first and second components to restrain the follower in a selected position within the adjustment range, and a disengaged position in which the detent is arranged to permit relative movement between the first and second components to permit the follower to move away from the selected position.   
     
     
         13 . An engine according to  claim 12 , wherein the detent actuator mechanism is operable by fluid pressure to move the detent, and the block includes a plurality of fluid channels, each channel fluidly communicating with a respective detent actuator mechanism to conduct fluid pressure to the detent actuator mechanism. 
     
     
         14 . An engine according to  claim 1 , wherein the follower control mechanism includes an actuator mechanism, the actuator mechanism including at least one actuator operatively associated with the follower and moveable by fluid pressure to move the follower within the adjustment range, and the block includes a plurality of fluid channels, each channel fluidly communicating with a respective actuator mechanism to conduct fluid pressure to the actuator mechanism. 
     
     
         15 . An engine according to  claim 14 , wherein the actuator is moveable by fluid pressure in one direction against a resilient restoring force. 
     
     
         16 . An engine according to  claim 14 , wherein the actuator is reciprocally moveable by fluid pressure in two opposite directions, and the actuator mechanism is provided with two said fluid channels to apply fluid pressure in the two opposite directions. 
     
     
         17 . An engine according to  claim 1 , wherein each valve lift assembly is received in a cylindrical hole in the block. 
     
     
         18 . A valve lift assembly for a cam-in-block engine, the engine including:
 a block;   a plurality of valves; and   a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis;   the valve lift assembly being configured to be mounted in the block in operative association with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis, and including:   a follower configured to rest in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis; the follower being moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and   a follower control mechanism operable to control the movement of the follower within the adjustment range.   
     
     
         19 . A method of providing adjustable valve operation in a cam-in-block engine, the engine including:
 a block;   a plurality of valves;   a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis; and   a plurality of valve lift assemblies, each valve lift assembly being mounted in the block and operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis; each valve lift assembly including:
 a follower, the follower being arranged in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis; 
   the method comprising:   mounting each follower for movement through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and   providing, in each valve lift assembly, a follower control mechanism operable to control the movement of the follower within the adjustment range.   
     
     
         20 . A method according to  claim 19 , wherein the valves include intake valves and exhaust valves, and a first group of valve lift assemblies are operatively associated with the intake valves and a second group of valve lift assemblies are operatively associated with the exhaust valves, and a control system is provided for independently controlling the valve lift assemblies of the first and second groups.