Abstract:
A normally closed ignition grounding switch mounted on the engine operates in concert with the fuel valve such that in order to “kill” the engine, the fuel valve must be moved from its open position. In one embodiment, a normally closed push button switch is mounted on the engine shroud in a position such that it is aligned with the sliding fuel valve lever so that the switch is released only when the fuel valve is moved toward its closed position. In an alternative embodiment, a normally open push button switch is mounted to the engine shroud aligned with the lever of the fuel valve such that closing the fuel valve depresses the push button switch.

Description:
CROSS REFERENCE 
   This application is a continuation-in-part of patent application entitled “Small Engine Shut Off System”, Ser. No. 11/112,353 filed Apr. 22, 2005, which is hereby incorporated in its entirety, now abandoned. 

   BACKGROUND OF THE INVENTION 
   This invention pertains to small gasoline engines and particularly to apparatus to force closure of the fuel supply valve to cause the engine to stop. 
   In the typical small gasoline engine, a manually activated switch is provided on the engine body which grounds the magneto of the engine when the user wishes to stop the engine from running. The engine is also equipped with a manually operable valve which may be activated to close the fuel line leading from the fuel reservoir to the engine fuel intake. When a small internal combustion engine is to be moved, it is especially advisable to close the fuel valve to prevent gasoline from draining into the engine as the engine is jostled and moved about, leading to overload of the intake valve of the carburetor and permitting gasoline to enter the combustion chamber. Gasoline in the combustion chamber when the engine is not running can cause delubrication of parts of the engine, namely the piston rings and cylinder wall. Manuals for small engines often carry instructions for the user to close the fuel supply valve when the engine is not running especially if it is to be moved, but many users pay little heed to these instructions, instead merely killing the engine and proceeding to move the equipment. As a result, lawn mowers, pressure washers, cement finishing equipment, and many other transportable devices powered by gasoline engines are transported from worksite to worksite with their fuel supply valves open, allowing gasoline to enter the engine eventually causing premature failure of the engine components. The loss of engines due to premature failure is a common and expensive problem which could be avoided with proper precautions or a system which would require closure of the fuel supply valve when the engine is stopped. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides a solution to the problem of a user&#39;s failure to close the fuel supply valve of a small internal combustion engine when the engine is not running. An ignition grounding switch may be mounted on the engine which is operable in concert with the fuel valve such that in order to “kill” the engine, the fuel valve must be closed. In one embodiment, a push button normally closed switch may be mounted on the engine cover in a position such that it is aligned with the sliding fuel valve lever and will be depressed when the fuel valve is moved to its open position. Alternatively, an ignition grounding switch may be combined with the fuel valve lever to accomplish stopping the engine only when the fuel valve is fully closed. 
   It is accordingly an object of the invention to provide a system to prevent premature deterioration of the engine piston and cylinder by preventing fuel from entering the combustion chamber when the engine is not running. 
   It is also an object to provide a system which forces the closure of the fuel supply valve when the engine is desired to be stopped from running. 
   It is further an object to provide a simple and inexpensive modification for an internal combustion engine to cause closure of the fuel supply valve in order to terminate the engine&#39;s operation. 
   These and other objects of the invention will become apparent from examination of the description and claims which follow. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a front elevation of an internal combustion engine equipped with the preferred embodiment of the invention. 
       FIG. 2  is schematic representation of the preferred embodiment of the invention. 
       FIG. 3  is front elevation of an internal combustion engine equipped with an alternative embodiment of the invention. 
       FIG. 4  is schematic representation of the alternative embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a typical horizontal drive shaft internal combustion engine  110  is illustrated which has been modified with the preferred embodiment of the invention. Engine  110  comprises a fuel reservoir  112  which is communicative through a fuel supply valve by suitable ducts to the carburetor of the engine. Engine  110  also includes an air cleaner housing  114  atop carburetor housing  116 . The fuel supply valve of engine  110  is manually operable by slide lever  120  which is shown in the closed position in  FIG. 1 . In the open position of the fuel supply valve with slide lever  120  moved to the right most position, fuel from fuel reservoir  112  may pass as needed to the carburetor within carburetor housing  116  where it is metered for consumption by engine  110 . 
   The flywheel of engine  110  is covered by shroud  118  on which may be mounted a normally closed switch  130  which when closed will couple the magneto output of the engine  110  to ground to prevent firing of the spark plug. Switch  130  is preferably a normally closed push button switch, that is, when not depressed, switch  130  is closed. Switch  130  could be some other normally closed, biased switch which returns to closed condition when not affected by exterior forces. In the preferred embodiment, the position of the switch  130  is selected such that it is in alignment with the locus of travel of slide lever  120  along slot  124 . Because switch  130  is operable by depressing push button  132 , when fuel valve slide lever  120  is moved to the open position by moving it in a right hand direction as viewed in  FIG. 1 , the handle  126  of slide lever  120  will touchingly engage push button  132  causing it to depress and to open the switch  130  thereby removing a ground connection to the spark plug. 
   Because the movement to open position of fuel valve slide lever  120  depresses push button  132  to open the connection between the magneto and ground, engine  110  is enabled to run. In order to cease operation of engine  11 , a user must move slide lever  120  along slot  124  to close the fuel valve in order to allow push button  132  to extend, thereby closing switch  130  to its normally closed condition, whereupon the magneto becomes grounded and the engine cannot run. Therefore, in order to stop the engine  110 , the user must close the fuel valve. 
   Though the preferred embodiment of the invention has been illustrated in  FIG. 1 , it should be understood that many variations of the invention may be constructed in which closure of the fuel supply valve of the engine is required to effect closure of a grounding circuit to the spark plug causing it to be disabled and the engine  110  to stop. 
     FIG. 2  illustrates schematically the interaction of the fuel supply valve  140  and the grounding switch  130 . As seen in  FIG. 2 , a voltage inducing coil such as magneto  142  is electrically coupled to system ground  150  on one side and it is coupled at output terminal  148  to the active terminal  146  of spark plug  144  on the other side such that voltage generated in magneto  142  will energize spark plug  144 . The active terminal  146  of spark plug  144  is coupled to switch  130  which is preferably a normally closed push button switch or some other switch which is biased to rest in an closed position causing active terminal  146  to be grounded until the switch  130  is caused to open. Switch  130  is mechanically coupled to fuel valve  140  such that until fuel valve  140  is closed, switch  130  will be prevented from closing. Therefore, in order for engine  110  to be stopped, fuel valve  140  must be moved to closed position. Conversely, in order for engine  110  to be enabled to run, fuel valve  140  must be moved from its open position to permit fuel to reach the combustion chamber and switch  130  must be opened. In the preferred embodiment illustrated in  FIG. 1 , touching contact between the valve slide lever  120  and push button  132  accomplishes the opening of the ground connection to the magneto and the spark plug when the fuel valve  140  is opened. 
   With this arrangement, the user of engine  110  will be required to close the fuel supply valve  140  when cessation of engine operation is desired. 
   Though the preferred embodiment of the invention has been illustrated in  FIGS. 1 and 2 , it should be understood that many variations of the invention may be constructed in which closure of the fuel supply valve of the engine must be made to cause closure, of a grounding circuit to the spark plug causing it to disable the engine  110 . For instance, the normally closed grounding switch  130  could be integrated with the fuel valve  140  in order that the engine  110  will not stop until the fuel valve  140  is closed. As another alternative, the normally closed grounding switch  130  could be located other than on the shroud  118  of engine  110  so long as any stoppage of engine operation cannot be effectuated unless the fuel valve  140  is moved to its closed position. 
   Modification of an engine  110  in factory equipped condition may be made using a kit comprising a normally closed temporarily open push button switch with conductors for connection to ground  150  and to the magneto  142 . A hole may be made in the shroud  118  to mount the switch such that the push button of the switch will be pushed by the fuel valve lever when it is moved to its open position. Any existing grounding switch on the engine would be disconnected or removed. 
   Referring now to  FIGS. 3 and 4 , an alternative engine grounding system is disclosed. Referring specifically to  FIG. 3 , a typical horizontal drive shaft internal combustion engine  10  is illustrated which has been modified with the alternative embodiment of the invention. Engine  10  comprises a fuel reservoir  12  which is communicative through a fuel supply valve by suitable ducts to the carburetor of the engine. Engine  10  also includes an air cleaner housing  14  atop carburetor housing  16 . The fuel supply valve of engine  10  is manually operable by slide lever  20  which is shown in the open position in  FIG. 3 . In the alternative embodiment, the slide lever  20  operates conversely to slide lever  120  of the preferred embodiment. In the open position of the fuel supply valve with slide lever  20  moved to the leftmost position, fuel from fuel reservoir  12  may pass as needed to the carburetor within carburetor housing  16  where it is metered for consumption by engine  10 . 
   The flywheel of engine  10  is covered by shroud  18  on which may be mounted a normally open switch  30  which when closed will couple the magneto output of the engine  10  to ground to prevent firing of the spark plug. Switch  30  is a normally open push button switch. The position of the switch  30  is selected such that it is in alignment with the locus of travel of slide lever  20  along slot  24 . Because switch  30  is operable by depressing push button  32 , when fuel valve slide lever  20  is moved to the closed position by moving it in a right hand direction as viewed in  FIG. 3 , the handle  26  of slide lever  20  will touchingly engage push button  32  causing it to depress and to close the switch  30  thereby grounding the spark plug. 
     FIG. 4  illustrates the alternative embodiment schematically showing the interaction of the fuel supply valve  40  and the grounding switch  30 . As seen in  FIG. 4 , magneto  42  is electrically coupled to system ground  50  on one side and it is coupled at output terminal  48  to the active terminal  46  of spark plug  44  on the other side such that voltage generated in magneto  42  will energize spark plug  44 . The active terminal  46  of spark plug  44  is coupled to switch  30  which may be a normally open push button switch or some other switch which rests in an open position preventing active terminal  46  from being grounded until the switch is caused to close. Switch  30  is mechanically coupled to fuel valve  40  such that the adjustment of fuel valve  40  to a closed position will cause switch  30  to close, thereby grounding the magneto output terminal  48  and spark plug  44 . In the alternative embodiment illustrated in  FIGS. 3 and 4 , touching contact between the valve slide lever  20  and push button  32  accomplishes the grounding of the spark plug when the fuel valve  40  is closed. 
   The foregoing description of the invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations of the embodiment are possible in light of the above disclosure or such may be acquired through practice of the invention. The embodiments illustrated were chosen in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and by their equivalents.