Centrifugal clutch with an overspeed relief valve and clutch modulation

A fluid pressure operated clutch for transmitting torque from an output shaft on an engine to a transmission input shaft, comprising:

• (a) a rotatable flywheel means for connection to the engine output shaft;
• (b) an adapter means connected to said flywheel means for rotation with said flywheel means, including a first annular plate having a first fluid passage near the inner periphery of said first plate;
• (c) a centrifugal piston means for defining with said adapter means a first fluid chamber, including a second annular plate slidable with respect to and rotatable with said first annular plate and having a second fluid passage near the outer periphery of said second plate, said first plate and said second plate, at their inner peripheries, providing means for varying the flow rate of fluid into said first fluid chamber as said second plate slides;
• (d) centrifugal relief valve means for discharging fluid from said first fluid chamber through said second passage when the engine overspeeds, including a body means connected to said second plate and having a second fluid chamber in fluid communication with said first chamber through said second passage, an outlet means for said second chamber and a conical valve means removably seated on said outlet means to open and close said outlet means;
• and
• (e) a clutch pack means, responsive to movement of said piston means, for coupling the engine output shaft to the transmission input shaft.

Apparatus for controlling the pressure on a clutch pack of a centrifugal clutch for an engine to control the engagement and disengagement of the clutch, comprising:

• (a) means for exerting forces on the clutch pack to engage and disengage the clutch in response to fluid pressure produced by centrifugal force, said exerting means having a first rotatable chamber being adapted to receive fluid;
• and
• (b) relief valve means for relieving fluid from said first chamber in response to engine overspeed, including
• (i) a body having a second chamber having a first inner compartment and a second outer compartment in fluid communication with each other, a fluid inlet being adapted to continually communicate said first chamber with said second chamber, and a fluid outlet being coupled to said second compartment, said body being coupled to said first chamber;
• and
• (ii) means for opening and for closing said outlet in response to centrifugal force and for assisting the opening or closing of said outlet with a predetermined force in response to fluid pressure in said first compartment and said second compartment.

Apparatus according to claim 32 wherein said means for opening and for closing and for assisting the opening or closing includes:

• (a) a head member being slidably coupled in said first compartment;
• (b) a valve member being removably seated on said outlet, said head member and said valve member each being constructed to provide an area to fluid pressure assist the opening or closing of said outlet or to fluid pressure balance the opening and closing of said outlet;
• and
• (c) means for interconnecting said head member and said valve member.

A centrifugal fluid relief valve, comprising:

• (a) a body having an inner bore of a first fluid compartment and a second fluid compartment in communication with said first compartment, an open fluid inlet in communication with said first compartment, and a fluid outlet having an edge and being in communication with said first compartment;
• (b) a conical valve member being removably seated on said edge, said edge being constructed to provide line contact with said valve member;
• (c) a head member being movably coupled in said second compartment, said valve member and said head member each being constructed to provide an area to fluid pressure assist the opening or closing of said outlet or to fluid pressure balance the relief valve;
• (d) a connecting rod extending through said first compartment and said second compartment and connecting said head member to said valve member;
• and
• (e) a sleeve being coupled in said second compartment about said rod.