Valve control system with a variable timing hydraulic link

A valve tappet mechanism and control system for use in an internal combustion engine comprising:

• a cam shaft including at least one lobe with a valve opening surface and a valve closing surface rotationally mountable within an internal combustion engine:
• a valve reciprocably slidable within an internal combustion engine:
• tappet means positioned between said cam shaft and said valve to open and close said valve in accordance with said valve opening and valve closing surfaces of said lobe, said tappet means including a cam follower and a piston connected by a hydraulic link means for providing an operational length to said tappet means with said hydraulic link means in an extended position and a collapsed length with said hydraulic link means collapsed, said cam follower operatively positioned to ride on said cam shaft, and said piston operatively connected to said valve;
• pressurization means for permitting supply and drainage of hydraulic fluid to and from said hydraulic link means and for expanding said hydraulic link means and said tappet means to said operational length and collapsing said hydraulic link means and said tappet means to said collapsed length, said pressurization means including a fluid line in communication with said hydraulic link means;
• timing control means connected to said fluid line for controlling said pressurization means to expand said tappet means to said operational length for at least a portion of the time that said cam follower rides on said valve opening surface and to collapse said hydraulic link means and said tappet means at an early closing time when said cam follower rides on said valve closing surface, said timing control means including a fluid gating means for further connecting said fluid line to a dump line at said early closing time to collapse said hydraulic link means, said fluid gating means including a rotary valve means for coupling said fluid line and said dump line to permit fluid passage from said fluid line to said dump line;
• and
• variable means for determining said early closing time taking into account engine operating conditions.

An internal combustion engine having at least one cylinder with a reciprocable piston therein, further comprising:

• a cam shaft including at least one lobe with a valve opening surface and a valve closing surface rotationally mounted within said internal combustion engine;
• an intake valve reciprocably slidably provided with said internal combustion to open and close an intake passage to said at least one cylinder;
• tappet means positioned between said cam shaft and said valve to open and close said valve in accordance with said valve opening and valve closing surfaces of said lobe, said tappet means including a cam follower and a piston connected by a hydraulic link means for providing an operational length to said tappet means with said hydraulic link means in an extended position and a collapsed length with said hydraulic link means collapsed, said cam follower operatively positioned to ride on said cam shaft, and said piston operatively connected to said valve;
• pressurization means for permitting supply and drainage of hydraulic fluid to and from said hydraulic link means, for expanding said hydraulic link means and said tappet means to said operational length and for collapsing said hydraulic link means and said tappet means to said collapsed length;
• timing control means for controlling said pressurization means to expand said tappet means to said operational length for at least a portion of the time that said cam follower rides on said valve opening surface and to collapse said hydraulic link means and said tappet means at an early closing time when said cam follower rides on said valve closing surface;
• variable means for determining the early closing time depending on engine operating conditions;
• and
• an axial internal cavity with which said piston is axially slidable, an annular chamber at an inwardmost end of said internal cavity that is radially wider than said internal cavity, an axial groove on an external surface of said cam follower in communication with said fluid line, and an opening connecting said annular chamber to said axial groove, wherein said axial groove extends axially on said cam follower for a distance at least equal to a stroke distance of said tappet means.