Briggs & Stratton, LLC

Joseph R Harkness

Gerald C Ruehlow

Thomas J Green

Patrick J Bruener

Daniel E Braun

Norbert M Vogl

Robert K Mitchell

Igor Kamlukin

Glen C Eifert

Robert Couchman, Jr

Ronald R Gaulke

William R Frank

The engine balancing system preferably has two pivoting counterbalance weights connected to eccentric journals on the crankshaft via their respective link arms. The use of the two pivoting weights and the particular geometrical relationships between the balancing system components enable the balancing system to substantially mimic and oppose the non-sinusoidal piston forces. Several methods of balancing the non-sinusoidal piston forces are disclosed. In a first method, the centers of gravity of the respective counterbalance weights are moved at non-sinusoidal angular accelerations. These angular accelerations are greater when the piston is near its Top Dead Center position than when the piston is near its Bottom Dead Center position to yield higher balancing forces when the piston is near Top Dead Center. In a second method, the centers of gravity move through arcs which are substantially parallel to the piston axis when the piston is near its Top Dead Center position, and move in directions less parallel to the piston axis when the piston is near its Bottom Dead Center position. The movement of the centers of gravity parallel to but in the opposite direction from the moving piston when the piston is near Top Dead Center results in greater balancing forces when the piston is near Top Dead Center. The invention also includes a combined method of balancing the non-sinusoidal piston forces. In this combined method, the angular accelerations of the centers of gravity vary as in the first method, and the directions of movement of the centers of gravity vary as in the second method.

Engine balancing system having at least one pivoting counterbalance

Internal combustion engine

A speed governing apparatus for an internal combustion engine. A plurality of flyweights are pivoted to a flyweight carrier mounted on the cam shaft of the engine and a surface of each flyweight is engaged with the end of a spool that is mounted for rotation with the cam shaft, but can move axially thereof. A spring loaded non-rotatable fork straddles the cam shaft and is engaged with the opposite end of the spool. The fork is secured to a rod which, in turn, is operably connected to the throttle of the engine. The end of the spool, against which the fork rides, is an undulating cam surface which results in the continuous axial oscillation of the spool, and corresponding continuous radial oscillation of the flyweights relative to the spool, during operation of the engine. The radial oscillation of the flyweights relative to the spool reduces the frictional forces, so that under varying load conditions the spool can be more readily moved by the pivoting action of the flyweights to provide more precise speed control.

Speed governing apparatus

A balance system for an internal combustion engine or the like includes a counterbalance weight pivotally mounted to the crankcase and driven in a reciprocating manner by a link assembly connecting the weight to an eccentric on the crankshaft. The pivoting weight not only counterbalances the piston acceleration and deceleration forces but also cancels the torsional forces created by the weight as it pivotally moves through an arc in response to piston movement. This is accomplished by locating the center of gravity of the balance weight between the piston bore centerline and the stationary pivot of the balance weight itself. This location for the center of gravity causes a torque to be generated by a force couple created by the piston inertial force vector, the balance weight interial force vector, and the distance between them. This torque counteracts the torque generated by angular acceleration of the balance weight itself, to thereby substantially eliminate all torsional vibrations.

Pivoting balancer system

An engine-balancing system for balancing the primary forces of single cylinder and in phase in-line multi-cylinder piston engines. The balancing system includes rotary, auxiliary counterweights mounted on the exterior of the engine block for rotation about fixed axes that are parallel to and spaced from the crankshaft axis and positioned at diametrically opposite sides thereof. The combined centrifugal forces of these auxiliary counterweights are preferably equal to that of the conventional crankshaft-carried counterweights. The auxiliary counterweights are drivingly-connected with the crankshaft by a flexible double-sided timing belt that is trained over sprockets of the same diameter coaxially fixed with respect to the crankshaft and with each of the pair of auxiliary counterweights so that the pair of auxiliary counterweights turn at the same speed as, but in the opposite direction from that of the crankshaft. The auxiliary counterweights coact with one another and with the conventional crankshaft-carried counterweight to significantly diminish vibration of the engine incident to its operation.

Reciprocating piston-type internal combustion engine with improved

A completely enclosed combination clutch and brake mechanism permanently mounted at the bottom of a vertical shaft internal combustion engine of the type used to power rotary lawn mowers, is interposed between the crankshaft of the engine and a coaxial blade shaft projecting down from the bottom of the enclosed clutch and brake mechanism to have the cutting blade of the mower fixed thereto. A rotatable driving member fixed to the engine crankshaft and a rotatable driven member fixed to the blade shaft are drivingly coupled by radially outwardly movable clutch elements carried by the driven member and frictionally engaged with a radially inwardly facing circular surface on the driving member. Such frictional engagement results from the application to the clutch elements of both spring force and centrifugal force. The spring-force-produced frictional engagement effects transmission of rotation to the driven member from stand still to the speed at which the centrifugal-force-produced frictional engagement is capable of transmitting full engine torque to the blade shaft, but is incapable--due to slippage--of stopping the engine when the brake is applied, in which event rotation of the driven member is rapidly decelerated to zero.

Clutch-brake mechanism for rotary mower engines

An engine powered rotary lawn mower has a brake which upon being engaged stops the engine crankshaft and the cutter blade fixed thereto. A deadman control on the handle of the mower, upon being moved partway to the 'run' position in which it must be held to enable operation of the mower, disengages the brake. A manually activated gravity deactivated latch holds the deadman control in brake-off position to enable starting the engine, until the deadman control is moved all the way to the 'run' position whereupon gravity deactivates the brake.

Brake safety system for a power driven rotary mower

A combination clutch and brake for rotary power mowers of the type wherein the blade is fixed to a spindle driven by the engine through an endless belt type drive transmission. A medially pivoted lever has an idler roll at one end to engage and tension the belt and thereby activate the drive transmission when the lever is rocked in one direction and a claw at its other end which, upon movement of the lever in the opposite direction, engages the notched periphery of a brake disc encircling the blade spindle and frictionally engaged with a companion disc that is fixed with respect to the spindle. The lever is spring-biased in the direction to engage the brake disc and thereby stop blade rotation concomitantly with deactivation the drive transmission whenever a deadman control on the mower handle is released.

Combination clutch and brake for rotary power mower

A rotary power mower in which the cutter blade is fixed to the bottom of a cup-shaped rotor, freely rotatably suspended from a carriage that is slidably mounted for fore and aft movement beneath the deck of the mower chassis. The carriage is spring-urged to a position in which the outer face of the side wall of the cup-shaped rotor is frictionally engaged with a brake shoe fixedly carried by the mower chassis, to hold the cutter blade against turning; and a deadman control mounted on the handle of the mower and operatively connected with the carriage enables the operator to move the carriage against the force of the spring to a position in which the inner face of the side wall of the cup-shaped rotor is tangent to and frictionally engaged with the periphery of a drive wheel fixed to the engine drive shaft.

Rotary power mower with improved clutch and brake mechanism

A brake mechanism for quickly stopping the drive shaft of an internal combustion engine on a power driven rotary mower.

In a walk-behind rotary lawn mower powered by a gasoline engine, two pushbutton-type switches are so connected in the engine ignition circuit that at least one must be actuated for the engine to run. One switch comprises a dead-man control actuated by gripping the mower guide handle. The other is actuated by a treadle so located on the mower deck as to be depressed by one foot of a person who has his other foot in a safe position and who is operating the engine rope starter in a natural, convenient manner. Depression of the treadle also actuates a brake that prevents the mower from rolling.

Safety device for walk-behind rotary mowers

In an internal combustion engine, a latch member is movable to and from a latching position in which it prevents a valve from coming nearer its seat than a predetermined distance therefrom. A cam follower connected with the latch member cooperates with axially adjacent first and second cam elements. The first causes the latch member to be held out of latching position during most of the engine cycle at all speeds, but at cranking speeds causes it to move to latching position just before the valve, in closing, reaches said distance from its seat. Once in latching position, the latch member is trapped there until opening movement of the valve carries it beyond said distance from its seat. The second cam element, carried by a flyweight, so cooperates with the first at running speeds as to hold the latch member out of latching position throughout the cycle.

Automatic compression relief mechanism for internal combustion engines

A mechanical lock-out by which a Bendix-type starter for an internal combustion engine is rendered incapable of starting the engine if mechanism - such as the propulsion system of a power lawn mower or tractor - has been drivingly connected with the engine. The lock-out comprises a lever pivoted to the housing of the starter with a part thereof in the path of the driving pinion of the starter as it advances towards meshing engagement with the ring gear on the engine flywheel, so that the lever must be free to move with the advancing driving pinion for the starter to be operative, and a blocking member, also pivotally mounted on the housing of the starter, for movement to and from an operative position preventing such movement of the lever. A Bowden wire connects the blocking member with a manually shiftable control by which the driving connection between the mechanism to be driven and the engine is activated, to move the blocking member to its operative position as a consequence of establishing the driving connection. Resilient yieldability incorporated in the blocking member prevents damage to the mechanism in the event the blocking member is moved into its operative position after the starter has been activated.

Growing community of inventors

Germantown, WI, United States of America

Joseph R Harkness