Internal-combustion engines – Starting device – Mechanical
Reexamination Certificate
2001-02-09
2001-11-06
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Starting device
Mechanical
C074S00700R, C185S0410WW, C192S045000
Reexamination Certificate
active
06311663
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an internal combustion engine. The present invention also relates to a device and method for starting the internal combustion engine, and, more specifically, to an engine starting device that is capable of storing energy in an elastic member and then releasing the energy to start the engine. The present invention also relates to a device and method for stopping the internal combustion engine or, at least, for absorbing energy of the engine upon shutdown. The engine starting device is particularly adapted for use with small internal combustion engines such as those provided on power lawn mowers, generators, snow blowers, garden tractors, and other machinery.
Small internal combustion engines have been equipped with manually operable recoil starters which include a central shaft, a rope pulley rotatable about the central shaft, retractable clutches or dogs connected to the rope pulley and a starter rope wrapped around the rope pulley. The starter rope may be pulled to rotate the rope pulley in a starting direction, such that the dogs engage the flywheel, and the flywheel and the crankshaft are also rotated in a starting direction. The engine is then driven through a number of revolutions sufficient for starting.
Although recoil starters of the type described above are commonly used with small internal combustion engines, there are certain disadvantages inherent in their operation. For example, the operator must possess a sufficient amount of strength and manual dexterity to pull the starter rope to rotate the flywheel and crankshaft. Under some conditions, the operator may have to pull the starter rope several times before the engine is successfully started. For some operators, this is a mere inconvenience. For other operators, including the elderly and the physically challenged, pulling a starter rope multiple times may present a difficult task.
An alternative to recoil starters and other manual starters are automatic starters which include a battery-powered electric motor for driving the flywheel through initial starting revolutions. Such a starter may be actuated by merely activating an electrical switch in the form of a push button or key device. Although this concept provides an engine starting device that is both easy to operate and generally effective, the electric motor, the battery used to power the motor, and associated components can add weight and cost to an engine. For small internal combustion engines such as those intended for use with lawn mowers, generators, and like machines, adding even a small amount of weight and cost to the engine can negatively impact the market competitiveness of the engine and/or the machine.
Another type of automatic starter is an engine starting device that utilizes stored energy in a spring to rotate the crankshaft and to start the engine. In these engine starting devices a mechanism must be provided to wind the spring. For example, U.S. Pat. No. 1,936,554, which is assigned to Briggs and Stratton Corporation (the assignee of the present invention) discloses an electric motor that is positioned adjacent the spring and which may be operated to wind the spring. It is also known to provide a manual crank mechanism interconnected with the spring and operable to wind the spring. Further, it is known to provide a winding mechanism interconnected with the crankshaft that is operable to wind the spring during normal engine running conditions.
SUMMARY OF THE INVENTION
In an internal combustion engine having a rotatable engine assembly or member, such as an assembly comprising a crankshaft, flywheel and output device (e.g., a cutting blade), the rotatable engine member contains kinetic energy due to its angular momentum after the engine ignition is shut-off by an operator. In some applications, the angular momentum is sufficient to move the rotatable engine member through multiple revolutions. A general feature and advantage of the present invention is a device or mechanism for utilizing the energy inherent in a rotatable or rotating engine member or assembly of a small internal combustion engine after the operator initiates shutdown of the engine (e.g., by operating a switch in a magneto or battery ignition system). More particularly, it is a feature and an advantage of the invention to provide, in such a mechanism or device, an engine starting device adapted for use with small internal combustion engines, and alternatively, to provide a machine that incorporates such an engine starting device.
For purposes of description, the terms “shutdown” and “shut-off” shall apply to the operation of a switch in the ignition system or an equivalent mechanism to turn the engine off. These terms shall also apply to any operation that effects the same result. The term “engine coast down” shall apply to the condition, status, or phase of the engine and/or rotatable engine member after engine “shutdown” or “shut-off” is initiated, but before the rotatable engine member ceases movement or rotation.
It is yet another feature and an advantage of the invention to provide a mechanism for braking a rotatable engine member upon engine shutdown, wherein the energy of the rotatable engine member is absorbed and/or stored by the braking mechanism.
It should be noted that, in the United States and other countries, a device is required on lawn mowing machines for arresting the rotation of the cutting blade within a specific time period after the operator initiates engine shutdown. Typically, the cutting blade is connected to the crankshaft such that it stops rotating at the same time that the engine stops reciprocating. Accordingly, a brake mechanism may be applied to the flywheel during engine shutdown to arrest rotation of the cutting blade. The braking mechanism of the present invention is also adapted for such an application.
In one aspect of the invention, the engine starting device includes an energy storing mechanism, an input element, and an output element. The energy storing mechanism includes at least one elastic member. The input element is engageable with the elastic member and movable during engine coast down to load the elastic member to a loaded state (e.g., by compressing, stretching, or flexing the elastic member). The output element is movable in response to the energy storing mechanism as the elastic member unloads from the loaded state. In this way, the output element moves or rotates the rotatable engine member in a starting direction, thereby driving the engine through initial engine revolutions sufficient for starting.
The engine starting device may also include an input control device for positioning the input element in engagement with the rotatable engine member such that the input element is movable by the rotatable engine member to load the elastic member. In one embodiment, the input element includes a rotatable input member (e.g., a friction roller or gear) movable by the input control device between a first position and a second position. In the first position, the rotatable input member is rotatably engageable with the rotatable engine member. The input member may be adapted to engage different portions of the rotatable engine member including the crankshaft, the flywheel, a ring gear attached to the flywheel, or a starter-type cup interconnected with the crankshaft. When disposed in the second position, the rotatable input member is rotatably disengaged from the rotatable engine member. Further, the engine may be equipped with an engine control device actuable to initiate shutdown of the engine. In this case, the input control device may be operatively connected with the engine control device such that the input control device is actuated to position the input element in engagement with the rotatable engine member whenever the engine control device is actuated.
In one particular embodiment of the invention, the input control device includes a manual actuator (e.g., a push button or deadman bail handle), a control cable, a pivotable housing supporting the input element
Brown Charles
Dethloff Steven
Dykstra Richard
Feldner John
Filipak Stanely
Briggs & Stratton Corporation
Dolinar Andrew M.
Michael & Best & Friedrich LLP
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