Tecumseh Products Company

Gordon E Rado

G Michael Adams

Arcady Royzen

Leonard E Gescheidle

David R Brower

Dennis N Stenz

John F Hoffman

Adam F Cox

A self-propelled mower with blade and ground speed controls. The mower includes a motor with an output shaft and a rotatable cutting blade mounted on a blade shaft. The motor may be an internal combustion engine. A torque transmitting mechanism such as a variable diameter pulley defines a rotational speed ratio between the output shaft and the blade shaft. A transmission is coupled to the output shaft. Sensors provide an electronic control unit with the blade speed, ground speed and engine speed. The ECU may be used to maintain either a desired blade speed or a desired ground speed. To maintain a desired blade speed, the ECU monitors the blade speed and, when the blade speed diverges from the desired speed, adjusts either the rotational speed ratio of the output shaft and blade shaft or the ground speed of the mower to maintain the desired blade speed.

Blade and ground speed control system

An evaporative emissions control system for small internal combustion engines includes a control valve associated with a fuel line and with a vent line which each connect the fuel tank to the carburetor. When the engine is not running, the control valve automatically closes the vent line and the fuel line, thereby trapping fuel vapors within the fuel tank and vent line and preventing the supply of liquid fuel to the carburetor. Upon engine start up, actuation of a bail assembly or vacuum produced within the carburetor causes the control valve to open the vent line and the fuel line, venting fuel vapors from the fuel tank through the fuel line to the carburetor for consumption by the engine, and opening the supply of liquid fuel from the fuel tank to the carburetor. Also, the present evaporative emissions control system may be used in conjunction with one or more fuel tank sealing and venting assemblies, which prevent the escape of fuel vapors from the fuel tank into the atmosphere, yet which allow fluid exchange in a closed manner between the fuel tank and carburetor.

Emissions control system for small internal combustion engines

An evaporative emissions control system for small internal combustion engines. A control valve assembly includes a pair of control valves which are respectively associated with a fuel line and with a vent line which each connect the fuel tank and the carburetor of the engine. The control valve assembly is automatically operable responsive to the rotation of a rotatable member of the engine drive train, such as the crankshaft, camshaft, flywheel, governor assembly, or other rotatable member. In one embodiment, for example, the control valve assembly is driven from the flywheel. When the engine is not running, the flywheel is stationary and does not rotate, and the control valves automatically closes the vent line and the fuel line, thereby trapping fuel vapors within the fuel tank and blocking the supply of liquid fuel to the carburetor. Upon cranking of the engine for start up, a flyweight mechanism of the control valve is driven by rotation of the flywheel, and centrifugal force acting on the flyweight mechanism causes the control valve to automatically open the vent line and the fuel line, venting fuel vapors from the fuel tank through the vent line to the carburetor for consumption by the engine, and opening the supply of liquid fuel from the fuel tank to the carburetor.

Centrifugally operated evaporative emissions control valve system for internal combustion engines

An engine control system for maintaining the operator-commanded speed setting of an internal combustion engine over a range of engine loads and for easy starting and improved efficiency over a range of ambient and engine operating temperatures. The engine control system includes a governor assembly driven by the engine, the governor assembly supplying an output to a sensor assembly through a mechanical coupling member operator. The sensor assembly provides an engine speed control signal which corresponds to operator commanded engine speed and actual engine speed. The engine speed control signal is provided to a throttle actuator to control actual engine speed is controlled to correspond with the operator-commanded engine speed regardless of loads imposed on the engine.

Engine control system for internal combustion engines

A priming system for the carburetor of a small internal combustion engine which is used with a lawnmower, for example, in which the priming system is remotely actuated. The priming system includes a priming feature for supplying an amount of liquid fuel to the carburetor throat to aid in starting the engine, and an enrichment feature for providing an enriched fuel supply to the engine during a warm-up period. In one embodiment, the priming system includes an automatic primer disabling feature which is operative when the engine is warm to block the supply of priming fuel to the carburetor throat and thereby prevent priming during a warm engine re-start. In another embodiment, the priming system includes a primer reduction feature, which is operative when the engine is warm to provide a reduced amount of priming fuel to the carburetor throat during a warm engine re-start, with respect to the amount of fuel which is supplied during a cold engine start.

Automatic engine priming system for rotary mowers

A fuel injector including a piezoelectric actuator directly attached to a metering rod wherein when the actuator is distorted in proportion to an input voltage, the metering rod moves to vary the size of a discharge spray orifice. The input voltage, and therefore the distortion of the actuator, may be varied in accordance with the readings from a throttle position sensor or an oxygen sensor, for example. A dual actuator type of fuel injector is also provided which has an injector body in engagement with the combustion chamber and a fuel chamber therein to receive low pressure fuel. A piezoelectric actuator moves a piston to close the fuel chamber inlet and pressurize the fuel therein. A second piezoelectric actuator moves the metering rod to open the discharge orifice. The amount of distortion of the respective actuators effects proportional movement of the piston or the metering rod.

Piezoelectric actuated fuel injectors

A priming system for a carburetor for small internal combustion engines, wherein the priming system is remotely actuated and includes an automatic primer disabling feature operative when the engine is in a warm condition to prevent the supply of an overly rich fuel/air mixture to the engine intake system during warm re-starts, for example.

A four-stroke internal combustion engine includes a cylinder block including a cylinder therein and having a piston reciprocally disposed within the cylinder. A piston is operably engaged with a crankshaft. At least one intake valve is reciprocally driven by a camshaft. At least one exhaust valve is reciprocally driven by the camshaft. A vacuum release mechanism includes an operating member reciprocally supported within the camshaft for translation along an axis. A centrifugally actuated flyweight member is engaged with the operating member, wherein rotation of the camshaft above engine cranking speeds causes the flyweight member to move the operating member from a first position to a second position. A vacuum release member is movably supported within the camshaft and is in engagement with the operating member wherein translational movement of the operating member causes movement of the vacuum release member. The operating member and flyweight are urged to the first position at engine cranking speeds and moved by the flyweight member through centrifugal force to the second position at engine running speeds. The vacuum release member is in lifting engagement with one of the valves at the first position during at least a portion of the power stroke of the piston and out of lifting engagement with one of the valves at the second position.

Mechanical compression and vacuum release

A four-stroke internal combustion engine includes a cylinder block having a cylinder therein and a piston reciprocally disposed within the cylinder. The piston is operably engaged with a crankshaft. At least one intake valve and one exhaust valve is reciprocally driven by a camshaft. A vacuum release mechanism includes an operating member rotationally supported by the camshaft and has an operator disposed thereon. A centrifugally actuated flyweight member is attached to the operating member, wherein rotation of the camshaft above engine cranking speeds causes the flyweight member to rotate the operating member. A vacuum release member is reciprocally supported by the camshaft and in engagement with the operator wherein rotational movement of the operating member causes radial translation of the vacuum release member through the operator. The operating member and flyweight member are urged to a first position at engine cranking speeds and rotated by the flyweight member through centrifugal force to a second position at engine running speeds. The vacuum release member is in lifting engagement with one of the valves at the first position during a portion of the power stroke and out of lifting engagement with the valve at the second position.

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Plymouth, WI, United States of America

Gordon E Rado