Abstract:
A common engine speed control mechanism for small internal combustion engines, which may be configured to allow for actuation of the speed control mechanism between stop, idle, and various engine running speed positions by actuation of one of a selected plurality of speed control levers. Each of the plurality of speed control levers is oriented so that it is movable in a direction which is substantially non-parallel to the direction of movement of the other speed control levers. In one embodiment, the actuation of the common speed control mechanism can be accomplished by movement of a first speed control lever in a substantially horizontal, side-to-side direction or by movement of a second speed control lever in a substantially vertical, up-and-down direction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to small internal combustion engines of the type used with lawnmowers, lawn tractors, other utility implements, and in sport vehicles, for example and, in particular, relates to speed control mechanisms for such engines.  
         [0003]     2. Description of the Related Art  
         [0004]     Small internal combustion engines typically include a carburetor which supplies an air/fuel mixture to one or more combustion chambers of the engine for combustion to drive the piston(s) and the crankshaft of the engine. The engine speed is typically regulated by a throttle valve disposed within the intake passage of the carburetor, which is movable between a substantially closed position corresponding to the engine being stopped or the engine running at a low or idle speed, and a substantially open position, corresponding to the engine running at its running speed.  
         [0005]     Many small internal combustion engines also include a governor for maintaining a desired running speed of the engine, including a mechanical governor mechanism disposed within the crankcase and driven from the crankshaft. The governor mechanism may include one or more flyweights movable responsive to engine speed, which actuate a governor arm within the crankcase and a governor lever disposed externally of the crankcase. The governor lever is linked to the throttle valve of the carburetor. In operation, when the engine speed falls below a desired running speed, such as when a load is imposed upon the engine, the governor operates to further open the throttle valve of the carburetor to increase the engine speed. When the engine speed increases beyond a desired running speed, such as when a load is removed from the engine, the governor operates to further close the throttle valve of the carburetor to decrease the engine speed.  
         [0006]     Many small internal combustion engines also include a speed control mechanism which is operable by an operator to set the running speed of the engine. The speed control mechanism includes a speed control lever which may be disposed either near the engine itself, or on the handle of an implement with which the engine is used. The speed control lever is movable between stop, idle, and various running speed positions, for example, to set the engine speed. When the speed control lever is disposed in the stop position, the throttle valve of the carburetor is substantially fully closed. When the speed control lever is disposed in the idle position, the throttle valve of the carburetor is slightly open to maintain a low engine running speed. When the speed control lever is moved through the various running speed positions toward a high speed position, the throttle valve is progressively opened to provide progressively higher engine running speeds. When the throttle lever is positioned to establish a desired running speed, that running speed is maintained by the governor responsive to engine load in the manner described above.  
         [0007]     In small internal combustion engines that include a speed control mechanism, the speed control mechanism is typically oriented entirely in a substantially horizontal or a substantially vertical plane, wherein actuating movement of the speed control lever of the speed control mechanism occurs in the same plane. For example, the speed control lever for a horizontally mounted speed control mechanism is operable to adjust the speed control mechanism between stop, idle, and the various running speed positions by movement of the speed control lever in a substantially horizontal, side-to-side direction. Similarly, the speed control lever for a vertically mounted speed control mechanism is operable to adjust the speed control mechanism between stop, idle, and the various running speed positions by movement of the speed control lever in a substantially vertical, up-and-down direction.  
         [0008]     One disadvantage of known speed control mechanisms is that the orientation of the speed control level is dictated by the orientation of the speed control mechanism. Often, a horizontally mounted speed control lever is desirable for applications such as go-karts, garden tillers, and other similar applications, while a vertical speed control lever orientation is desirable for snow throwers or other applications. Therefore, for different engine types, one speed control mechanism must be designed for mounting for horizontal, side-to-side actuation and a different speed control mechanism must be designed for vertical, up-and-down actuation, necessitating increased cost and increased total parts and inventory.  
         [0009]     What is needed is a speed control mechanism for small internal combustion engines which is an improvement over the foregoing.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention provides a common engine speed control mechanism for small internal combustion engines, which may be configured to allow for actuation of the speed control mechanism between stop, idle, and various engine running speed positions by actuation of one of a selected plurality of speed control levers. Each of the plurality of speed control levers is oriented so that it is movable in a direction which is substantially non-parallel to the direction of movement of the other speed control levers. In one embodiment, the actuation of the common speed control mechanism can be accomplished by movement of a first speed control lever in a substantially horizontal, side-to-side direction or by movement of a second speed control lever in a substantially vertical, up-and-down direction.  
         [0011]     In one embodiment, the speed control lever forms a right angle interface with the speed control mechanism. This interface facilitates the conversion of motion in a first plane to motion in a second, transverse plane. In one embodiment, the right angle interface utilizes a combination of links and pivots. In another embodiment, the right angle interface is a pin and slot connection. In another embodiment, the right angle interface is a rack and pinion gear mesh.  
         [0012]     Each of the embodiments disclosed herein advantageously allows the speed control mechanism of a small internal combustion engine to be adjusted by the movement of either of a plurality of speed control levers along respective non-parallel axes or directions. The present system allows for a single, common speed control mechanism to be used with different engines by selectively configuring the common speed control mechanism based on the intended use of the engine. For example, the speed control mechanism, when configured for use with an internal combustion engine in a snow thrower, may have an operator control element interface attached to a vertical speed control lever to allow the operator to control the speed of the engine by vertical, up-and-down movement of the operator control element interface. Alternatively, the speed control mechanism, when configured for use with an internal combustion engine in a go-kart, may have an operator control element interface attached to a horizontal speed control lever to allow for the operator to control the speed of the engine by horizontal, side-to-side movement of the operator control element interface.  
         [0013]     In one form thereof, the present invention provides an internal combustion engine, including a support, a speed control lever pivotally mounted to the support, the speed control lever including at least first and second operator control element interfaces, and an operator control element connected to one of the operator control element interfaces, the operator control element movable to pivot the speed control lever with respect to the support.  
         [0014]     In another form thereof, the present invention provides a speed control assembly kit for an internal combustion engine, including a support, a speed control lever pivotally mounted to the support, a first operator control element connected to the speed control lever for movement of the first operator control element and the speed control lever in substantially the same plane, and a second operator control element connectable to the speed control lever for movement of the second operator control element and the speed control lever within substantially perpendicular planes. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0016]      FIG. 1   a  is a perspective view of a small internal combustion engine showing an operator control element interface attached to a horizontal speed control lever;  
         [0017]      FIG. 1   b  is a fragmentary view of a portion of the engine of  FIG. 1   a;    
         [0018]      FIG. 2   a  is a perspective view of a small internal combustion engine showing an operator control element interface attached to a vertical speed control lever;  
         [0019]      FIG. 2   b  is a fragmentary view of a portion of the engine of  FIG. 2   a;    
         [0020]      FIG. 3  is a top plan view of a speed control mechanism including an operator control element interface positioned as depicted in the internal combustion engine of  FIGS. 2   a  and  2   b;    
         [0021]      FIG. 4  is a perspective view of the speed control mechanism;  
         [0022]      FIG. 5  is a perspective view of the speed control mechanism, with the speed control mechanism in an engine stop position;  
         [0023]      FIG. 6  is a continuation of  FIG. 5 , showing the speed control mechanism disposed in a high engine running speed position during normal operation of the engine;  
         [0024]      FIG. 7  is a fragmentary perspective view of the speed control mechanism, showing the speed control levers configured according to a second embodiment of the present invention with the speed control mechanism disposed in an engine stop position;  
         [0025]      FIG. 8  is a continuation of  FIG. 7 , showing the speed control mechanism at a high engine run speed position;  
         [0026]      FIG. 9  is a fragmentary perspective view of a portion of an engine;  
         [0027]      FIG. 10  is a fragmentary perspective view of the speed control mechanism, showing the speed control levers configured according to a third embodiment of the present invention. 
     
    
       [0028]     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate preferred embodiments of the invention and such exemplifications is not to be construed as limiting the scope of the invention any manner.  
       DETAILED DESCRIPTION  
       [0029]     Referring to  FIGS. 1   a - 2   b , a small internal combustion engine  10  is shown, including a speed control mechanism according to the present invention.  
         [0030]     Engine  10  may be of the type of small internal combustion engines manufactured by Tecumseh Power Company of Grafton, Wis., and includes known components not visible in the figures, including a crankcase and a cylinder block attached to the crankcase, with the cylinder block including one or more bores which receive pistons. Each piston is connected to the crankshaft of engine  10  via a connecting rod. Engine  10  is shown herein as a horizontal crankshaft engine; however, the present invention is equally applicable to vertical crankshaft engines. Some exemplary engines with which the present speed control mechanism, described below, may be used are disclosed in U.S. Pat. Nos. 6,295,959, 6,612,275, and 6,941,914, each assigned to the assignee of the present invention, the disclosures of which are hereby incorporated by reference. Engine  10  is of the type used in utility implements such as snow throwers, lawn mowers, and other utility implements, for example, the implement typically including a frame (not shown) to which engine  10  is attached. For example, when the implement is a snow thrower, engine  10  is mounted to a deck (not shown) which includes two or more wheels, and drives an auger mechanism. When engine  10  is used with a lawn mower, engine  10  is mounted to a deck (not shown) including wheels, and engine  10  drives a rotating cutting blade beneath the deck.  
         [0031]     Engine  10  includes a carburetor (not shown) connected to engine  10  in fluid communication with the combustion chamber(s) of the engine cylinder(s) to supply an air/fuel combustion mixture to engine  10  for combustion. The carburetor generally includes an intake air passage that extends from an inlet end of the carburetor to an outlet end of the carburetor which is in communication with combustion chamber(s) of the engine cylinder(s). The carburetor additionally includes a venturi section and a throttle valve rotatably mounted within the throat. Optionally, the carburetor may include a rotatable choke valve (not shown) controlled by choke valve lever  12 , shown in  FIG. 3 , movable by actuation of a choke valve operator interface, depicted as knob  14 .  
         [0032]     Engine  10  additionally includes a governor device for regulating and/or maintaining a set running speed of engine  10 . The governor device of engine  10  is similar to those disclosed in U.S. Pat. Nos. 4,517,942 and 5,163,401, each assigned to the assignee of the present invention, the disclosures of which are expressly incorporated herein by reference. The governor device is driven from the crankshaft or from the camshaft of engine  10  and responds to increases and decreases in engine speed by rotating governor lever  16 , shown in  FIG. 3 , a small distance. Governor lever  16  is linked to the throttle valve of the carburetor in a known manner, such as via link  18 , so that movement of governor lever  16  results in corresponding movement of the throttle valve of the carburetor.  
         [0033]     Additionally, governor lever  16  can be rotated, and the throttle valve of the carburetor correspondingly rotated as described above, by movement of speed control mechanism  20 , shown in  FIG. 3 . In this manner, movement of speed control mechanism  20  is translated into an increase or decrease in the running speed of engine  10 . Speed control mechanism  20  includes a primary speed control lever  22  and a secondary speed control lever  24  connected thereto via a right-angle connection, for example, as described below. Primary speed control lever  22  and secondary speed control lever  24  are oriented so that horizontal, side-to-side movement and vertical, up-and-down movement of speed control levers  22 ,  24 , respectively, corresponds to movement of speed control mechanism  20 , as described below. Secondary speed control lever  24  can be connected to speed control mechanism  20  by various angled connections, including, as described in detail below, links and pivots, a pin and slot connection, or a rack and pinion gear mesh.  
         [0034]     An operator control element, depicted as knob  26  in  FIGS. 1   a - 3 , can be attached to one or both speed control levers  22 ,  24 . As shown in  FIGS. 1   a - 2   b , engine  10  includes control panel  28 , including slots  30 ,  32 , on/off switch  34 , and choke valve lever  14 . Referring to  FIG. 5 , knob  26  can be connected to operator control element interface  36  of primary control lever  22  so that knob  26  extends through slot  30 , as shown in  FIGS. 1   a  and  1   b . Similarly, referring to  FIG. 5 , knob  26  can also be connected to operator control element interface  38  of secondary control lever  24  so that knob  26  extends through slot  32 , as shown in  FIGS. 2   a  and  2   b . Additionally, to prevent dust and debris from entering through slots  30 ,  32 , slots  30 ,  32  that lack knob  12  extending therethrough may have a decal or plate (not shown) covering slots  30 ,  32 .  
         [0035]     Referring to  FIG. 3 , details of speed control mechanism  20  will now be described. Speed control mechanism  20  includes many features similar to the speed control mechanism disclosed in U.S. Pat. No. 6,279,298 assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. Speed control mechanism  20  includes a support, shown herein as mount plate  40 , which may be secured to the crankcase or to the cylinder block of engine  10  by suitable fasteners. Primary speed control lever  22  and governor actuator lever  42  are each rotatably mounted to mount plate  40  at pivot  44  via a lost motion-type connection. Secondary speed control lever  24  is mounted on pivot post  46  of mount plate  40 . Primary speed control lever  22  and secondary speed control lever  24  are movable between the positions shown in  FIGS. 5 and 6 , with the positions corresponding to engine stop and high engine running speed positions, respectively. Throughout the foregoing positions of primary speed control lever  22 , secondary speed control lever  24  and governor actuator lever  42  correspondingly rotate therewith.  
         [0036]     Primary speed control lever  22  may include knob  26 , shown in  FIGS. 1   a  and  1   b , attached to operator control element interface  36 . Knob  26  may be made of suitable plastic, for example, for grasping directly by an operator to rotate primary speed control lever  22 . Alternatively, to provide for remote actuation of speed control levers  22 ,  24 , the operator control element may be a Bowden-type cable  48 , shown in  FIG. 9 , attached to primary speed control lever  22  or to secondary speed control lever  24 . As shown in  FIG. 3 , primary speed control lever  22  is coupled to secondary speed control lever  24  via a right angle interface, comprising links  50  connected at pivots  52 ,  54 . Governor actuator lever  42  is coupled to primary speed control lever  22  at pivot  44  and includes a first portion  56  extending generally upwardly. First portion  56  is connected to protrusion  58  of governor lever  16  via spring  60 . Fixed plate  59  is connected to both primary speed control lever  22  and governor actuator lever  42  at pivot  44 . Fixed plate  59  maintains tension on governor lever  16  via spring  61  connected thereto. Governor lever  16  is, as described in detail above, connected at a pivot point by link  18 , which is connected to the throttle valve of the carburetor of engine  10 .  
         [0037]     Secondary speed control lever  24  may include knob  26 , as shown in  FIGS. 2   a  and  2   b , which may be made of suitable plastic, for example, for grasping by an operator to rotate secondary speed control lever  24 . As discussed above with reference to primary speed control lever  22 , cable  48  could also be utilized with secondary speed control lever  24  to provide for remote actuation. As shown in  FIG. 3 , secondary speed control lever  24  may be coupled to primary speed control lever  22  by a right angle interface. In one embodiment, the right angle interface includes pivots  52 ,  54  and link  50 . Pivots  52 ,  54  and link  50  cooperate to translate the vertical, up-and-down movement of secondary speed control lever  24  around pivot post  46  into horizontal, side-to-side movement rotating primary speed control lever  22 .  
         [0038]      FIGS. 7 and 8  depict another embodiment of the speed control mechanism of the present invention as speed control mechanism  62 . Speed control mechanism  48  includes several components which are identical to the embodiments of  FIGS. 1-6  discussed above and identical reference numerals have been used to indicate identical or substantially identical components therebetween. Referring to  FIG. 7 , secondary speed control lever  64  is attached to mount plate  40  at pivot post  46 . Pin  66  extends substantially perpendicularly from secondary speed control lever  64 . Primary speed control lever  22  includes plate  68  extending upwardly therefrom. Plate  68  includes slot  70  sized to accept pin  66  therein. Pin  66  is disposed through slot  70  in loose engagement therewith. When secondary speed control lever  64  is rotated about pivot post  46 , pin  66  contacts portions of plate  68  defining slot  70 , rotating plate  68 , and, correspondingly, primary speed control lever  22  about pivot  46 .  FIG. 7  depicts speed control mechanism  62  in an engine stop position corresponding to engine  10  being stopped.  FIG. 8  depicts speed control mechanism  62  in a high engine running speed position, as discussed in detail above.  
         [0039]      FIG. 10  depicts another embodiment of the speed control mechanism of the present invention as speed control mechanism  72 . Speed control mechanism  72  includes several components which are identical to the embodiments of  FIGS. 1-6  discussed above and identical reference numerals have been used to indicate identical or substantially identical components therebetween. Referring to  FIG. 10 , secondary speed control lever  74  is attached to mount plate  40  at pivot post  46 . Secondary speed control lever  74  includes pinion gear  76  including teeth  78 . Teeth  78  mate with corresponding teeth  80  of rack  82  of speed control mechanism  72 . When secondary speed control lever  74  is moved in a vertical, up-and-down direction, speed control mechanism  72  rotates in the direction indicated by the arrows in  FIG. 10 .  
         [0040]     Referring to  FIGS. 5 and 6 , operation of speed control mechanism  20 , including primary speed control lever  22  and secondary speed control lever  24 , will now be described. In  FIG. 5 , speed control mechanism  20  is shown with primary speed control lever  22  and secondary speed control lever  24  at an engine stop position corresponding to engine  10  being stopped. In this position, primary speed control lever  22  is rotated clockwise, and secondary speed control lever  24  is rotated downward, to their furthest extents. Additionally, ignition switch  84  is touching contact  86 , which grounds the ignition system of engine  10  preventing engine  10  from starting. When an operator desires to start engine  10 , the operator moves primary speed control lever  22  counterclockwise, or moves secondary speed control lever  24  upward, to an idle position (not shown) to slightly open the throttle valve as described above and move contact  86  away from ignition switch  84 . Regardless of which speed control lever  22 ,  24  the operator moves, the position of both speed control levers will be correspondingly changed via the above-described linkage. The operator then actuates a pull-recoil starting mechanism (not shown) or an electric starter motor (not shown) to crank engine  10 , thereby drawing an air/fuel mixture into the carburetor for starting engine  10 . Optionally, the operator may actuate a primer mechanism (not shown) associated with the carburetor to supply an amount of priming fuel to the carburetor to aid in starting engine  10 .  
         [0041]     After the engine starts, the operator moves primary speed control lever  22  counterclockwise, or moves secondary speed control lever  24  upward, from the idle position to a desired engine running speed position, which is shown in  FIG. 6  as a high engine running speed position. For small internal combustion engines, normal high engine running speeds are typically between 1600 and 1400 rpm. In the high engine running speed position of primary speed control lever  22  and secondary speed control lever  24 , shown in  FIG. 6 , the above described linkage positions the throttle valve of the carburetor in a substantially open position, allowing a relatively large degree of intake air flow through the carburetor allowing engine  10  to run at a high speed.  
         [0042]     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.