Abstract:
A control system for the ignition circuit and carburetor of an internal combustion engine wherein a hand throttle lever is operatively connected to both a spring-urged carburetor lever and to switch means for the ignition circuit to provide normal operation of the engine but principally to provide for the safety of the operator in the operation of such circuit if the throttle lever becomes jammed or frozen or otherwise maintained in a speeding position and the operator loses control of such system. Three switches are mounted in a single housing which in turn is mounted on the handle or guiding bar for the vehicle, with one switch at the top portion of the housing and the other of two interrelated switches at the lower portion and each operatively connected to the throttle lever for operation of the ignition system while the third switch can be independently pushed by the operator to alone open said ignition circuit, with all three operating on a printed circuit panel within the housing which serves both as the electrical circuit for the three switches and the mounting member therefor in the complete control mechanism. The two interrelated switches can be identified as switches I and II and the third switch as a &#34;kill switch&#34;. The throttle lever is mounted at its upper end and at the upper rear portion of the housing in a pin and enlarged slot mounting which provides a lost motion pivotal connection at said slot.

Description:
BACKGROUND OF INVENTION 
     The present invention provides a fail-safe control system particularly adapted for an internal-combustion-engine-driven snowmobile, but is also adapted for application to high speed outboard motor driven boats, motorcycles, engine driven riding lawnmowers, and similar units (all called &#34;vehicles&#34; in this specification) where the operator normally guides and operates the engine of the vehicle from throttle lever in an exposed position such that it can be jammed by a foreign object getting into the throttle lever assembly, or it will freeze and stick, or otherwise fail to decelerate the engine while operating at what could be a dangerous speed. Snowmobiles in particular have become popular and useful both for commercial and sports purposes and operating in cold weather, snow, and often in the brush these are particularly vulnerable to jamming, freezing, or the like in the throttle system such that the safety of the operator is in jeopardy if the vehicle cannot be stopped when the operator loses control of the unit. 
     This problem has been attacked in switches for such vehicles to insure the safety of the operator and U.S. Pat. No. 3,672,344 which issued June 27, 1972 on an application filed Sept. 11, 1970, U.S. Pat. No. 3,789,938 which issued Feb. 5, 1974 on an application filed Apr. 24, 1972, as well as U.S. Pat. No. 3,798,402 issued Mar. 19, 1974 on an application filed Apr. 19, 1972 are the answers of these patentees to a so-called safety system for such a vehicle. However, none of these prior switch systems provide the necessary safety to the operator for no one takes care of the situation wherein the engine is operating at high speed and the operator is unable to move the throttle lever and decelerate or stop the engine because of some one of the conditions described above, or the operator is thrown from the vehicle. There are also mechanical deficiencies in these prior switch systems independently of the lack of complete safety, but the latter is the significant problem which the present invention solves while providing a more sturdy, compact switch and control mechanism in a single housing with a throttle lever therewith and with the housing mounted on the handlebar of the vehicle. 
     One of the important uses for snowmobiles is in the brush or in rough country, or in other environments where the exposed position of the control and guiding mechanism in the open cockpit is particularly vulnerable to twigs, branches, and other foreign materials becoming wedged in the throttle control system at the handlebar. Furthermore, snowmobiles are operated in exceedingly cold climates where heavy gloves are necessary for the operator, and these can become jammed in the throttle mechanism without fault of the driver. The control system of the present invention takes care of these situations, and the switches thereof act to open the ignition circuit for the engine and stop the engine should the driver lose control because of the conditions mentioned, and this system causes the engine to decelerate to idle condition should the operator lose control by falling from the vehicle while operating at high speeds. 
     SUMMARY OF INVENTION 
     The control system of the present invention comprises a single two-part plastic housing adapted to fit directly on the handlebar of a snowmobile or the like having a throttle lever on the outside of the housing for engine control and pivotally supported by a pin mounted in an elongated slot in the housing to permit both pivotal and longitudinal movement of such pin in such slot. The housing includes a bore portion to accommodate the handlebar, and the throttle lever straddles the handlebar rearwardly on the housing and is mounted so as to be convenient to the driver or operator while he guides the vehicle with the handlebar. Within the housing and concentric with the bore for the handlebar so as to surround the same is a printed circuit board with contact pins and pivot supports selectively placed on the board and extending at right angles thereto with printed circuitry electrically connecting those pins while serving as contacts to three switches within the housing. Two of these switches are the principal operating switches for the ignition circuit of the internal combustion engine for the vehicle and are connected in parallel through the printed circuitry with such ignition circuit. These two switches are interrelated, are both operatively connected to the pivoted throttle lever, and each is selectively operated depending upon the position of the throttle lever to provide an idling speed or an accelerating operating speed for the internal combustion engine. The third switch mechanism in the control system is mounted within the housing, is connected to contact pins in the printed circuitry on the panel, and is operated by a manually operated button to open the ignition circuit in case of an emergency in which the operator is able to act and push the button inwardly toward the housing. It is commonly called a &#34;kill&#34; switch in this art and the present switch is always connected into one lead of the ignition circuit so as to open the circuit and kill the engine even though one or both of the normal operating switches are closed in such circuit. 
     With a single two-part housing, the single printed circuit board panel is a significant electrical and mechanical element in the assembly, the throttle lever, with the three switches compactly and ruggedly mounted within the housing, and with the housing quickly and simply mountable on the handlebar for the vehicle a very satisfactory commercial product is provided. The printed circuit board is electrically connected to the ignition system in a normal manner through electrical cables from the board, and the pivotally mounted throttle lever not only mechanically connects to the two interrelated operating switches, but is mechanically connected by a flexible cable extending from the lower portion of the lever, as will be explained more in detail hereinafter, through a bore in the housing, and connects to the carburetor lever on a carburetor shaft to control the gasoline feed to the engine in a normal manner. The carburetor lever in turn is connected to a return spring on the engine and such spring exerts a continuing bias on the throttle lever which is tensioned as the throttle lever is pivoted toward the handlebar by the operator as speed of the vehicle is increased. 
     The throttle lever has two integral leg portions on the outside of the housing straddling such housing and is pivoted toward and away from the housing during its normal hand operation by the driver or operator of the vehicle while under spring tension from the carburetor lever arm return spring. The mechanism of the switches and the pivot mounting of the lever under spring tension in the present invention solved the safety problem should foreign material of any kind, or a glove, be wedged between the throttle lever and the back face of the housing when such lever is in a high speed operating position and spaced from the housing. The principal pivot for the throttle lever is a pin supporting both legs of the lever as they straddle the housing with the pin retained in an elongated slot at the upper rear portion of such housing. The pin is operatively connected with switch I in a top position in the housing, and the lever engages a portion of switch II of the interrelated switches at the bottom portion of the housing. Spring pressure within switch I maintains the switch contacts open. 
     When the engine is started switch II is in closed position for the ignition circuit in an idle position, and as the throttle lever is raised to open the carburetor and to accelerate the engine the mounting pin moves forward in the elongated slot and acts to close switch I. Idle switch II is arranged and dimensioned so that it stays closed until after switch I is closed, and as the throttle-lever is pressed further toward the handlebar the pin moves to the front of the housing slot, switch I remains closed and thereafter switch II opens. The elongated slot mounting the lever pivot pin is only so long as to accommodate closing and opening of switch I and does not in any way result in a sloppy feel to the vehicle driver for the throttle lever, for with substantial speeds being possible with a snowmobile over smooth as well as very rough terrain it is important that the operator have a solid feel at his fingers and his hand on the handlebar for the throttle lever. 
     Switches I and II are in parallel in the ignition circuit through the circuit panel, and as described, one or both are closed to complete that circuit while the engine is running. The &#34;kill switch&#34; is closed at all times until manually opened and when opened breaks the ignition circuit and kills the engine. The dimensions or adjusted dimensions for switches I and II and the spring pressures on the contact members in such switches are such that as the throttle lever is moved upwardly and the engine accelerates the desired operations through the switches take place. To decelerate the engine, the throttle lever is released in the degree desired by the operator or driver, the spring tension on the throttle cable takes effect to pivot the throttle lever at its pin mounting, the lever engages and closes switch II, and the spring in switch I which has been compressed moves the spring contact out of engagement with pins on the control board to open that switch. However, if something prevents that full pivoted movement and jams the lever in its operating position with switch I closed, even though switch II is open in the ignition circuit, then with the driver&#39;s hand pressure removed from the throttle the retracting spring force on the carburetor cable to the throttle and the spring pressure in switch I take over and forces the top of the lever rearwardly in the elongated slot, opens switch I and opens the ignition circuit. Similarly, should the operator fall from the vehicle and his hand pressure removed from the throttle lever, if the throttle lever is jammed, both switches will be open. If the throttle lever is not jammed and pivots back to a normal decelerated idle position under the force of the spring on the throttle cable, the snowmobile stops at that time. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings; 
     FIG. 1 is a general illustration of a snowmobile showing the open cockpit or seating arrangement, the handlebar, and the present control system thereon; 
     FIG. 2 is a side view of the complete control system in the position of FIG. 1 as mounted on a portion of the handlebar; 
     FIG. 3 is a plan view at the line 3--3 in FIG. 2 looking in the direction of the arrows there shown with a fragment of the lever; 
     FIG. 4 is a side view of the housing and throttle lever for the complete unit mounted on the handlebar but turned some 60° clockwise from the position of FIG. 1 and showing in broken sections the first and the second switches as well as the elongated slot for the throttle lever pivot pin, with such portions in a size corresponding to a commercial embodiment; 
     FIG. 5 is a fragmentary cross-section through the line 5--5 of FIG. 4 and showing the detail of the pivot pin, slot, printed circuit board and elements of the first switch in the system; 
     FIG. 6 is a view of the printed circuit board, circuitry, and contact pins looking rearwardly from the front of the vehicle; 
     FIG. 7 is a view of the opposite side of the printed circuit board turned 180° clockwise from the position of FIG. 6; 
     FIG. 8 shows the assembly of the toggle-action mechanism of the &#34;kill switch&#34; in a side view on the circuit board together with switches I and II; 
     FIG. 9 is a detail of the switch bridge through line 9--9 and looking in the direction of the arrows in FIG. 8 with such bridge in closed and in open positions; 
     FIG. 10 is a face view of the &#34;kill switch&#34; looking to the right as the switch is illustrated in FIG. 8, and showing such switch in closed and open circuit positions; 
     FIG. 11 is an enlarged detail of switch I with the contact bridge in closed and open positions; 
     FIGS. 12 to 15 and 17 are diagrammatic views of the control system and ignition circuit as will be described in detail hereinafter, with FIG. 17 illustrating particularly pivot points for the throttle lever with the carburetor lever arm return spring and throttle cable; 
     FIG. 16 is a table showing the functional condition of each of the three switches in the control system at four operating and/or open circuit positions; 
     FIG. 18 is an exploded view of operating elements of the complete control system with a portion of the printed circuit control panel and a portion of the throttle lever fragmentized, as well as the throttle cable for connection to the carburetor lever; and 
     FIG. 19 is a front face view of the spring contact and molded guide member alone from FIG. 11. 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The control system of the present invention is illustrated as applied to a snowmobile in FIG. 1, but as previously pointed out it has an application for other internal combustion engine driven vehicles such as a marine unit with an outboard motor, a motorcycle, a rider-driven lawnmower, and the like where the possibility exists that something will happen to the control system or to the operator while the vehicle is travelling at a speed such that the vehicle gets out of control and it is necessary to have the engine stopped without using the manually operated &#34;kill switch&#34; or &#34;panic button&#34; in the present control system, but at the same time having the latter available. 
     The vehicle 10 has an open cockpit or seat for the operator and a handlebar unit 11 with the control system of the present invention shown here as mounted on the right-hand portion 12 while a hand brake is normally carried on the left-hand portion 13 of the handlebar. The complete mounted control system 14 is shown on the handlebar 12 in FIG. 1 and in a larger view in the same position in FIG. 2, while FIG. 4 shows the unit in actual size corresponding to one commercial embodiment of the invention. As viewed from the outside of the control system in FIGS. 1 through 3 a housing is provided in two plastic parts 16 and 17 fitting together into a closed unit with a bore 18 to accommodate the handle 12 extending through the entire housing. A one-piece molded throttle lever 19 is pivotally mounted in an elongated slot 20 in the housing by a pin 21 smaller in diameter than the slot is long and wide, with legs 22 and 23 (FIG. 5) straddling the outside of the housing and hence the handle 12 and being connected to a carburetor lever arm by a throttle cable 24 releasably connected at an anchor 25 (FIG. 18) with the throttle lever 19, and positioned in a cavity 25&#39; within the lever and extending through a bore 26 shown at the front of the housing in FIG. 2 and at the rear of the housing in FIG. 3. A slot 27 opening from one side of the housing permits the throttle cable to be readily disconnected from the lever 19, or changed upon breaking without disassembling the control system housing in any way. A button 28 for the &#34;kill switch&#34; extends out of the housing on the inside as it is viewed when mounted on the handlebar 12 and readily available to the operator just as the throttle lever 19 is operated by the driver of the vehicle while his hand is on the handlebar itself. 
     The ignition circuit and three switches are shown diagrammatically in FIGS. 12 to 15 and 17 for the operation of the internal combustion engine after it is started and show the switch and throttle lever position from an idle mode through an accelerating mode to the fully accelerated running mode. Switch I is at the top of the housing as viewed in FIG. 3 and switch II at the bottom of such housing, with the &#34;kill switch&#34; to one side as shown in FIG. 10. 
     The stationary contacts for such two operating switches, as well as the stationary contacts for the &#34;kill switch&#34; are all provided on a printed circuit board or panel 31 shown in a face view in FIG. 6, and in a reverse position in a perspective view in FIG. 7. The view in FIG. 6 is looking from the front of the housing in its position on the handlebar in FIGS. 1 and 2, while the view turned through 180° in FIG. 7 is looking from the rear toward the front of the control assembly on the snowmobile. The insulating board for the panel 31 provides a rugged foundation for the printed circuitry thereon, a sturdy base for the contact and support pins secured thereto, and an equally rugged member of the complete mechanical assembly for the system within the housing 14 as mounted in the part 17 of such housing. 
     The conductive metal for the switches and the ignition circuit includes portion 32 (FIG. 6) extending around three sides at the perimeter of the face of the board or panel 31 and a second portion 33 internally of the first portion. The electric contact pins 34 and 36 for switch I are secured in the panel 31, are electrically connected to the two conductors 32 and 33, and protrude from the back side to the front side as shown in FIGS. 6 and 7. Such pins for switch I are engaged by a U-shaped contact member 37 (FIG. 18) with spring contact arms 38 and 39 and a mounting hole 41 which receives the pin 42 integral with and projecting forwardly from a molded insulating carrier 43, which has a base 44 for the pin 42 that is also a part of the wall of the carrier and forming a pair of cavities 46 and 47 (FIG. 11). Each cavity 46 and 47 has a ledge 48 thereon which serves as a support for the respective contact arms 38 and 39 on the member 37. The enlarged detail in FIG. 11 is turned 90° clockwise relative to FIG. 18, for instance, so that the contact pins 34 and 36 and the contact arms 38 and 39 are more readily understandable with the carrier 43. As shown in FIG. 19 in a front view of the molded guide or carrier 43, and then in cross-section in FIG. 11, the arms of the spring contact 37 are positioned on the ledges in open circuit position in full lines and in closed circuit position in dotted lines, and illustrate the lateral movement of each arm 38 and 39 as each engages a corresponding contact pin. 
     The carrier 43 also includes a stud portion 49 as shown in FIGS. 11 and 18 for operative connection with the throttle lever. The contact bridge 37 is biased in its assembled position on the carrier 43 by a spring 51 mounted on the projection or pin 42 and abutting the PC board or panel 31 at one end and the bridge 37 at the other end. Pins 34 and 36 in the PC board 31 are engageable respectively in a wiping contact action with the contact portions 38 and 39 when the carrier is in closed circuit position as shown in dotted lines in FIG. 11. 
     The elements so far described for switch I are all employed in the assembly of switch II and the same numbers heretofore described for the elements of switch I are used in switch II merely with a prime added, except that the carrier 43&#39; for switch II as shown in FIG. 18 has open cavities 46&#39; and 47&#39; permitting a longer relative movement between the pins 57 and 58 in the cavities and the carrier 43&#39;, upon movement of the latter. 
     In the operative connection to the throttle lever 19, switch I includes a guide member 52 comprising an elongated body 55 which engages the pivot pin 21, and a portion 53 comprises a collet type sleeve engaging the stud 49 on the carrier. The collet type sleeve portion 53 is maintained on the stud 49 by a spring ring type retainer 56 (FIGS. 5 and 18) encircling the sleeve. When the switch is assembled in the housing 14 the guide 52 and carrier 43 are only partially coupled together at the stud and sleeve. After all of the components of the system are assembled in the housing and the two pieces 16 and 17 secured together by drive screws 50 and 50&#39; (FIG. 18) force is applied to the throttle lever 19 and the pivot pin 21 is forced to the extreme front end of the elongated slot 20 toward the board 31. This action drives the carrier 43 to a forward position in engagement with the ends of the contact pins 34 and 36, and continued pressure on the guide 52 by the pivot pin 21 causes the joint between the collet sleeve 53 and stud 49 on the carrier 43 to slip until the pivot pin 21 engages the furthest forward edge of the slot 20 in the housing corresponding to the position of the lever in FIG. 13. In a commercial embodiment of the invention as illustrated in the drawings, the ends of the contact pins 34 and 36 must be 0.045&#34; from this extreme position to break contact with the contact wiper. The slot 20 and the pin 21 allow 0.090&#34; axial movement of the guide 52. Therefore, in this final adjusted position of switch I with the sleeve 53 fully engaged and the spring clamp 56 holding the same the switch will open in the ignition circuit when the throttle lever pin 21 is allowed to back away 0.045&#34; from the board 31. With this structure and assembly for switch I the dimensions and the amount of travel can be altered as desired for different applications, but these dimensions given apply to the commerical embodiment here illustrated. 
     Switch II is for idle position of the engine and ignition circuit and as is shown in FIGS. 12 and 18 has a carrier 43&#39; and spring contact bridge 37&#39; essentially the same as described for switch I. It is assembled and operates on pins 57 and 58 mounted in the PC board 31 with the projection 42&#39; fitting into a hole 59&#39; in the PC board in the same manner that the projection 42 of switch I fits into the hole 59 at the top of the PC board as viewed in FIGS. 6 and 7 as well as FIG. 18. 
     As previously referred to, the differences in the carriers 43 and 43&#39; (FIG. 18) are required in this commercial embodiment so as to permit a greater amount of overtravel in switch II than in switch I, and the cavities 46&#39; and 47&#39; extend through the body of the carrier while they do not do so in carrier 43. The cavities 46 and 47 are closed in carrier 43 because it bottoms out against the ends of the contact pins 34 and 36 as described for the self-adjustment structure of switch I in initially adjusting the travel in that switch. In that respect there is not enough physical space in the housing to accommodate the self-adjusting feature for switch II, for as shown in FIGS. 4 and 18, the housing part 17 is enlarged at the upper portion relative to the lower portion and thus accommodates the longer assembly for switch I. 
     The &#34;kill switch&#34; mechanism will be described, and then the operation of all three switches will be described relative to the diagrammatic illustrations of the system in FIGS. 12 to 15 and 17. 
     The &#34;kill switch&#34; assembly as illustrated in FIGS. 8, 9 and 10 will be described along with the elements in the exploded view of FIG. 18 which latter comprise a molded plastic carrier 61 mounted on a pin 60 in the PC board 31 which also pivotally supports a U-shaped actuator 62 having one leg 63 connected with the carrier 61 through a torsion spring 64 while the other leg 66 includes a tang 67 thereon fitting into a cavity 68 in the shank of the button 28 for such switch. The operating mechanism for the &#34;kill switch&#34; is of the general toggle action type wherein pressing the button 28 inwardly as viewed in FIG. 10 pivots the U-shaped member 62 in a manner such that the torsion spring 64 is put under increased tension and pivots the carrier 61 to an open circuit position with the bridge member 69 in full line position in FIG. 9 tensioned in the three integral plastic pins, 70, 70&#39;, 70&#34; moved from the dotted line position where it electrically engages the contact pins 71 and 72. In reverse, when the &#34;kill switch&#34; is set in closed-circuit position for the ignition circuit, the button 28 is pulled out, toggle action occurs, and the V-shaped contact bridge 69 engages the two pins 71 and 72 in a wiping contact which knocks off any oxidation or foreign material and provides a good electrical contact through such switch. FIG. 9 is not large enough to permit an illustration of insulating pins 70, 70&#39; and 70&#34; as well as contact pins 71 and 72 in each of the two positions of contact bridge 69. Bridge 69, just as bridges 37 and 37&#39;, can be described either as U-shaped or V-shaped. 
     The pins 73 and 74 in the P.C. board 31 are the connections from such board to the ignition system for the internal combustion engine, and a plastic clip 82 (FIG. 18) holds a connector in position on such pins. 
     Referring to FIGS. 12 to 15 inclusive for the operation of the system, these illustrate the position of the three switches in the system as functionally shown in FIG. 16. FIG. 7 is revised relative to the other four circuit diagrams merely to more simply illustrate the pivot points in the system and the spring forces acting on the throttle lever and switches I and II which provide the reliable running as well as the fail-safe operation of the system. 
     First; more details as to the throttle lever 19 which includes an integral bump 76 on the leg portion 23 in contact with the rear face of the housing (FIG. 4), and an integral projection 77 on the leg portion 22 in contact with stud portion 49&#39; on the carrier 43&#39; for switch II. FIGS. 12 and 17 illustrate the starting or idle position for the ignition circuit with the lever 19 at its position of rest and the spring 78 attached to the pivoted carburetor arm 79 acting on such arm to pull the cable 24 and retain the throttle lever 19 at the position of rest or at idle mode. From this position as the lever 19 is pulled or pressed upwardly by the operator whose hand is on the handlebar 12 and whose fingers are on the throttle lever, the projection 77 of the lever 19 engages the stud 49&#39; on carriage 43&#39; and the spring tension on the cable 24 maintains the switch II closed, but as the lever 19 is pivoted at the bump 76 against the rear face of the housing the pivot pin 21 at the slot 20 moves forwardly in such slot as shown in FIG. 13. The members 43 and 52 between the pivot pin 21 and the contact bridge 37 move the arms 38 and 39 of the latter into the carriage cavities 46 and 47 (FIG. 11) and engage the contact pins 34 and 36 as shown in dotted lines in such figure. Meanwhile, the spring 78 is tensioned and exerts a force on the lever 19, while springs 51 and 51&#39; are each compressed for each of such operating switches I and II. The outward force from spring 51 is low and approximately 5 oz. in one commercial embodiment while the force of the spring 78 on the throttle cable 24 is high and approximately 18 oz. thus pulling the entire throttle lever 19 toward the housing and maintaining the projection 76 against the switch II carrier 43&#39;. The force of the spring 78 acting on the cable 24 and the upward pressure of the lever 19 to overcome the low spring force acting on the coupling elements of switch I operatively connect spring contact 37 in switch I and the pivot pin 21. Both switches I and II are connected in parallel and both closed at this accelerating position of the throttle lever so there is no possibility of the ignition circuit being opened in this condition of the engine. 
     As the lever 19 is pulled or pressed in a counterclockwise direction toward the handle 12 as shown in FIG. 14 the lever 19 (or indicated as B) pivots at pin 20 about point B (FIG. 17) and switch II acting from the force of spring 51&#39; opens at the spring contact 37&#39; and contact pins 57 and 58. In other words, the pivot point for the throttle lever 19 has changed from A to B in FIG. 17 under the hand pressure acting on the throttle lever 19 at C. 
     In decelerating or going from the full running speed of FIG. 14 to an idle mode the hand pressure is removed or reduced on the throttle lever 19. With the high spring force from the spring 78 acting on the cable 24 that force pulls the lever downward and forward and the pivot pin 21 is forced to the rear of the slot 20 by that force and the low force from the spring 51 in switch I. The lever 19 would normally pivot to the position of FIG. 12 and the engine would run at idle speed. 
     However, FIG. 15 illustrates foreign material 81 wedged between the rear face of the housing 14 and the inside portion of the lever 19 so as to prevent the projection 77 from contacting the switch II carrier 42&#39; at 49&#39; and so as to prevent the bump 76 from engaging the housing. As described above, the engine is running at full speed in FIG. 14, and it is at this speed or at least a running speed that the foreign object 81 such as a branch, twig or the operator&#39;s glove occupies the illustrated position of an object 81. At that time, the lever 19 is pivoting around point B in FIG. 17, and actually is at the rear end of the elongated slot 20 for the tension on cable 24 and the force of spring 51 causes the pin 21 to move to the rear of slot 20. Switch I is thus open and it has not been possible to close switch II because of the obstruction. The ignition circuit is opened as shown in FIG. 15 even though the operator might be helpless to decelerate the engine to idle mode. 
     Should the throttle cable 24 to the carburetor arm 79 break, the force from spring 78 on the cable 24 could no longer pivot the lever to the position of FIG. 12, and the force of the respective springs 51 and 51&#39; on switches I and II will maintain the respective bridges 37 and 37&#39; in each switch carrier out of contact with the two terminal or contact pins for each of such respective switches. Likewise, if the spring 78 breaks, or if it becomes disengaged from the carburetor arm 79, switches I and II will open. The ignition circuit with both switches I and II open as in FIG. 15 will be broken and the engine will stop. As has also been described, and as the illustrations show, the circuit can be broken by pushing button 28 and opening that circuit through the &#34;kill switch&#34;. 
     Accordingly, the diagrammatic illustrations in combination with the structural illustrations show that the present invention will provide a ready control of the engine and ignition circuit in an application such as a snowmobile while it is accelerating. In addition, it provides a sturdy and automatically operating system wherein the engine is killed or brought to a stopped idle position should the operator be prevented from himself bringing the vehicle to such a position or condition.