CA1111940A - Engine r.p.m. control system for snowmobile - Google Patents
Engine r.p.m. control system for snowmobileInfo
- Publication number
- CA1111940A CA1111940A CA297,346A CA297346A CA1111940A CA 1111940 A CA1111940 A CA 1111940A CA 297346 A CA297346 A CA 297346A CA 1111940 A CA1111940 A CA 1111940A
- Authority
- CA
- Canada
- Prior art keywords
- engine
- speed
- lead
- voltage
- snowmobile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Ignition Installations For Internal Combustion Engines (AREA)
Abstract
ENGINE R.P.M. CONTROL SYSTEM FOR SNOWMOBILE
Abstract of the Disclosure A snowmobile is provided with an engine R.P.M. control system which may be selectively actuated to either maintain engine speed below drive engagement speed or below a speed thought to be excessive for the engine and/or drive design.
Abstract of the Disclosure A snowmobile is provided with an engine R.P.M. control system which may be selectively actuated to either maintain engine speed below drive engagement speed or below a speed thought to be excessive for the engine and/or drive design.
Description
C~
1 ENGINE R.P.M. CONTROL SYSTEM FOR SNOWMOBILE
The present invention relates to a safety control system for a vehicle and more specifically relates to a safety control system for preventing a vehicle from "running away" in the event that its throttle sticks and for preventing the vehicle engine from overspeeding in the event that the load is suddenly removed from the engine as might be occassioned by a drive train element breaking while the engine is under load with the vehicle operating at or near full throttle.
While the problems solved by the present invention may occur with a large number of vehicles they seem to occur more frequently with snowmobiles due to the latter being operated in an environ-ment which contributes to stuck throttles and due to the use of drive trains which can fail in various ways resulting in the load being suddenly removed from the engine.
Previous attempts of solving the problem of runaway has been to provide the snowmobile with a normally open switch connected to the ignition system such that the ignition will be grounded out whenever the switch is released. This has no~ proved satis-factory however since an operator may inadvertently release theswitch resulting in the engine of the snowmobile stopping when it is not intended or desired that it do so.
Summary of the Invention According to the present invention, there is provided a novel vehicle engine control.
An object of the invention is to provide an engine control means for preventing vehicle "runaway" during starting without inhibiting the normal operation of the vehicle.
More specifically, it is an obj~ct of the invention to provide an engine R.P.M. limiting control which operates to limit the R.P.M. of the engine below drive engagement speed during starting and which is selectively operable for limiting the R.P.M.
1- ~
- -3`~
l of this engine ~ust below its maximum designed operational speed.
These and othe~ objects will become apparent from a reading o~ the ensuing description together with the appended drawings.
Brief Description of the Drawings Fig. 1 is a perspective view of a snowmobile embodying the present invention.
Fig. 2 is a diagram of the engine R.P.M. limiting control circuitry.
Description of the Preferred Embodiment _ Referring now to Fig. 1, therein is shown a snowmobile lO
including a frame 12 having a pair of skiis 14 attached thereto adjacent the forward end thereof and a traction drive track 16 suspended beneath a rearward portion thereof. Mounted on the forward end of the frame 12 is an internal combustion engine 18.
Provided for driving the track 16 from the engine 18 is a variable speed drive 20 including a variable speed primary drive pulley 22 connected to an output shaft of the engine, a variable speed secondary drive pulley 24 connected to a countershaft and a drive belt 26 trained about the pulleys 22 and 24. The pulleys 22 and 24 are respectively speed and torque responsive and no torque will be transmitted therebetween until the engine speed reaches a predetermined engagement speed. A typical idle speed for a snowmobile engine might be in the neighborhood of 2,000 R.P.M.
with the engagement speed being about 3,000 R.P.M. and top design-ed speed being 6,500 R.P.M.
The speed of the engine is controlled by means of a throttle control including a lever 28 mounted on a right handle bar 30 of the snowmobile and coupled to a throttle assembly 32 by means of a sheathed cable 34. The lever 28 is mounted in a conventional manner, not specifically shown, whereby it is operative to open throttle valving in increasing amounts in accordance with increas-ing movement of a trigger portion of the lever 28 from a released l position spaced away from the handle bar 30 to a fully depressed position against the har.dle bar. Under normal circumstances, one or more r~turn springs 36 forming part of the throttle assembly 32 will act to retain the throttle valving to an "idle" position when the trigger portion of the lever 28 is released. However, if the sheathed cable 34 should bind or some other malfunction occur which prevents the throttle valving from so returning to its "idle" position upon the operator releasing the throttle control lever 28, then the valving will remain at whatever position to which it has been actuated to thus present a hazard in the event that the engine is to be started or an operator is thrown from the snowmobile lO with the throttle in a stuck open position.
Referring to Fig. 2, therein is shown an electrical engine R.P.M. control system 40 for eliminating or at least reducing the hazard just mentioned and for also reducing the possibility of engine or drive component damage as might occur as a result of a load suddenly being removed from the engine when the latter is operating at or near full throttle.
Specifically, the system 40 includes an ignition circuit comprising an alternator 42 which is driven by the engine 18 in a conventional manner for providing power through a lead 44 for firing a spark plug 46 in correspondence with the closing of a set of ignition points 48. Connected to the lead 44 is a lead 50, which contains a silicon controlled rectifier or SCR 52 that is switched, in accordance to an unsafe condition sensed by the remainder of the system 40, to connect the lead 50 to a ground lead 54 to ground out the ignition to maintain the engine speed at a safe value. ~-Forming an impor~ant part of the system 40 are a pair of identical integrated timing circuits which are indicated by the boxes 56 and 58. The circuits 56 and 58 may take many forms , . . . .
. .
hDW~Y~ ~hP C~ S ~hDS~ 2S~ h~ p~ r~ .y simila~ t~
ones su})~lied as part No. MC 14~ hy Motorola S~miconduct~:~
Products Inc. Each of the circuits 56 and 58 include a ground pin lr a trigger pin 2, an output pin 3, a reset pin 4, a control voltage pin 5, a threshold voltage pin 6, a ~ischarge volta~e pin 7, and a supply voltage pin 8. The supply voltage for driving the circuits 56 and 58 is provided by the alternator 42, which is connected to a power supply lead 60. Connected in series in the lead 60 is a rectifier diode 62 and a resistor 64. A lead 66 containing a capacitor 68 connects a junction 70, located between the diode 62 and resistor 64 with the ground lead 54 while a lead 72 containing a Zener regulator diode 74 is connected to the lead 60, after the resistor 64, and to the ground lead 54. Thus, as employed in the circuit, the diode 62, resistor 64, capacitor 68 and Zener diode 74 cooperate to provide a d.c. voltage equal to the reverse breakdown voltage of the Zener diode 74 to power the timing circuits 56 and 58. Accordingly, the power supply line 60 is connected to the supply voltage pins 8 of the circuits S6 and 58 respectively by leads 75 and 76 while the circuits 56 and 58 are respectively grounded by leads 77 and 78 connected between the ground pins 1 of the circuits and the ground lead 54. A lead : 80 is coupled to the supply line 60 ahead of the rectifier diode 62 and conveys an alternating voltage to the base of a txansistor 82 which results in the latter being turned on and off at a frequency equal to that o~ the voltage and thus at a frequency which corresponds to the engine R.P.M. A lead 84 is connected between the lead 80 and ground and contains a Zener diode 86 - which regulates the voltage in the lead 80 such that it is never negative nor exceeds the reverse breakdown voltage of the Zener diode 86.
The threshold and discharge voltage pins 6 and 7, respec-tively, of the timing circuit 56 are connected in parallel to a , ~ t~
1 lead of the timing circuit 56 are connected in parallel to a lead 90 which is connected to an emitter 92 of the transistor 82.
Thus, when the voltage in the lead 80 switches on the transistor 82, the latter conducts to connect the pins 6 and 7 to ground such as to cause a capacitor 94 to discharge, the capacitor 94 being located in a lead 96 connected between the power supply lead 60 and ground lead 54 and joined to the lead 90 at 98.
Connected in the lead 96 in series with the capacitor 94 is a resistor 100. When the capacitor 94 discharges and the transistor 82 switches off during the negative excursion of the voltage in line 80, the voltage at the pins 6 and 7 builds at a rate deter-mined by the time constant of the resistor 100 and capacitor 94, this time constant being designed to be less than the frequency of the voltage produced when the engine R.P.M. is at a value for effecting drive engagement speed but above idle speed. For example, if the engine idles at 2,000 R.P.M. and the drive 20 engages when the engine reaches 3,000 R.P.M., the time constant may be selected to correspond to a voltage frequency produced when the engine is operating between 2,400-2,500 R.P.M. Accord-20 ingly, if the engine is designed according to the example givenand is operating at some speed below 2,400 R.P.M. the frequency at which the transistor 82 is turned on and off will be suffici-ently low to permit the voltage in the lead 90 to attain a value greater than the threshold voltage of the timing circuit 56 during the time that the transistor 82 is turned off. The circuit 56 is designed such that during the time that the voltage at pin 6 is building from 0 to the threshold value the output voltage ~t pin 3 will be high, this voltage becoming low upon the threshold value of the circuit being reached. Thus, during slow R.P .M.
30 operation of the engine 18, the output voltage at pin 3 will change states at a frequency corresponding to the R.P.M. value.
_ 5 _ .: '' . - ' ` " '~ . :
, ~ : ' . . . - :
- . :
1 OI1 the other hand, should the speed of the engine 18 increase to a value above 2,400-2,500 R.P.M., the frequency at which the transistor 82 is turned on and off will be too high to permit the voltage in the lead 92 to ever attain a value greater than the threshold voltage of the circuit 56 during the time that the transistor 82 is turned off and the voltage at the output pin 3 will remain high.
The output pin 3 of the timing circuit 56 is connected by means of a lead 102, to the base of a transistor 104 having its 10 emitter 106 connected, by means of a lead 108, to the threshold and discharge pins 6 and 7 of the timing circuit 58. A lead 110, which is connected between the power supply lead 60 and ground lead 54, joins the lead 108 at 112 and connected in series in the lead 110 is a resistor 114 and capacitor 116. Anytime that the output voltage at the pin 3 is high, the transistor 104 is turned on to discharge the capacitor 116 to ground and anytime output voltage at the pin 3 is low, the transistor 104 is turned off and the voltage in the lead 108 builds at a rate determined by the time constant of the resistor 114 and the capacitor 116. This time constant is somewhat greater than that of the resistor 100 and capacitor 94 but still corresponds to an engine R.P.M. fre-quency below drive engagement speed, it being noted that the purpose of the circuit S8 is to give stability to the system to ensure that transient voltages do not efect unwanted control of the engine.
Thus, when the engine R.P.M. is below engagement speed and below that speed for producing a voltage having a frequency equal to the time constant of the resistor 100 and capacitor 94 and the output voltage at pin 3 changes from high to low at this fre-30 quency, and consequently the transistor 104 will be turned on andoff at this frequency. The time constant of the resistor 114 and capacitor 116 is sufficiently long that the threshold voltage of - -, . . . . ~: - . :
, , ~ ' " ' 1 the circult 58 is never reached and the voltage at the output pin 3 thereof remains high. However, if the R.P.M. of the snowmobile engine is equal to the preset critical limit of the circuit 56 such as to effect a constantly high output voltage at the pin 3 thereof, the transistor 104 will be constantly turned off permit ting the voltage at the pins 6 and 7 to go high resulting in the circuit 58 effecting a low voltage at its output pin.
The output pin 3 of the circuit 58 is connected, by means of a lead 118, to the base of a transistor 120 having its collector connected to the power supply lead 60 by a lead 122 and having its emitter 124 connected to ground by a lead 126. Connected between the lead 122 and the gate of the SCR 52 is a lead 128.
Whenever the output voltage at the pin 3 of the timing circuit 58 is high the transistor 120 is on and the gate voltage o the SCR
52 is low so that the latter is off. However, when the voltage at the output pin of the timing circuit 58 is low, the transistor is off and the gate voltage of the SCR 52 is high enough to gate the SCR 52 on to ground out the ignition to limit the snowmobile engine speed to a value below the critical speed.
Provided for permitting the engine to run at speeds in excess of engagement speed is circuitry including a resistor 130 connected in series with the resistor 100 by means of a lead 132 having one end connected to the power supply lead 60 and the other end connected to the lead 96. A normally open switch 134 is located in the lead 132 between the resistor 130 and power supply lead 60. The switch 134 would be located at a location convenient for actuation by the operator whenever he desired to operate the snowmobile engine at speeds above drive engagement speed. Such operation of the switch 134 changes the time constant 30 to a value equal to the product of the resistances of the resis- ~ -tor~ 100 and 134 divided by their sum and multiplied by the capacitance of the capacitor 94. Thus the time constant is .. . ~
. .
1 shortened such as to requ-re increased engine R.P.M. to effect turning on of the SCR 52. Thus a high speed limit is provided and it is selected to be just slightly below the maximum design speed o~ the engine 18 and/or drive 20. Thus, in the event that the drive belt 26 breaks or some other part of the traction drive 20 fails such as to remove the load from the engine 18 when the latter is being operated at or near full throttle, the engine ignition will be controlled to limit the speed of the engine below the maximum design speed.
10Should the operator be thrown from the snowmobile 10, the switch 134 will immediately open to automatically re-establish the lower speed limit whereby the engine ignition is controlled such as to lower the engine speed below that for effecting drive engagement.
~, - 8 ~
, . .
1 ENGINE R.P.M. CONTROL SYSTEM FOR SNOWMOBILE
The present invention relates to a safety control system for a vehicle and more specifically relates to a safety control system for preventing a vehicle from "running away" in the event that its throttle sticks and for preventing the vehicle engine from overspeeding in the event that the load is suddenly removed from the engine as might be occassioned by a drive train element breaking while the engine is under load with the vehicle operating at or near full throttle.
While the problems solved by the present invention may occur with a large number of vehicles they seem to occur more frequently with snowmobiles due to the latter being operated in an environ-ment which contributes to stuck throttles and due to the use of drive trains which can fail in various ways resulting in the load being suddenly removed from the engine.
Previous attempts of solving the problem of runaway has been to provide the snowmobile with a normally open switch connected to the ignition system such that the ignition will be grounded out whenever the switch is released. This has no~ proved satis-factory however since an operator may inadvertently release theswitch resulting in the engine of the snowmobile stopping when it is not intended or desired that it do so.
Summary of the Invention According to the present invention, there is provided a novel vehicle engine control.
An object of the invention is to provide an engine control means for preventing vehicle "runaway" during starting without inhibiting the normal operation of the vehicle.
More specifically, it is an obj~ct of the invention to provide an engine R.P.M. limiting control which operates to limit the R.P.M. of the engine below drive engagement speed during starting and which is selectively operable for limiting the R.P.M.
1- ~
- -3`~
l of this engine ~ust below its maximum designed operational speed.
These and othe~ objects will become apparent from a reading o~ the ensuing description together with the appended drawings.
Brief Description of the Drawings Fig. 1 is a perspective view of a snowmobile embodying the present invention.
Fig. 2 is a diagram of the engine R.P.M. limiting control circuitry.
Description of the Preferred Embodiment _ Referring now to Fig. 1, therein is shown a snowmobile lO
including a frame 12 having a pair of skiis 14 attached thereto adjacent the forward end thereof and a traction drive track 16 suspended beneath a rearward portion thereof. Mounted on the forward end of the frame 12 is an internal combustion engine 18.
Provided for driving the track 16 from the engine 18 is a variable speed drive 20 including a variable speed primary drive pulley 22 connected to an output shaft of the engine, a variable speed secondary drive pulley 24 connected to a countershaft and a drive belt 26 trained about the pulleys 22 and 24. The pulleys 22 and 24 are respectively speed and torque responsive and no torque will be transmitted therebetween until the engine speed reaches a predetermined engagement speed. A typical idle speed for a snowmobile engine might be in the neighborhood of 2,000 R.P.M.
with the engagement speed being about 3,000 R.P.M. and top design-ed speed being 6,500 R.P.M.
The speed of the engine is controlled by means of a throttle control including a lever 28 mounted on a right handle bar 30 of the snowmobile and coupled to a throttle assembly 32 by means of a sheathed cable 34. The lever 28 is mounted in a conventional manner, not specifically shown, whereby it is operative to open throttle valving in increasing amounts in accordance with increas-ing movement of a trigger portion of the lever 28 from a released l position spaced away from the handle bar 30 to a fully depressed position against the har.dle bar. Under normal circumstances, one or more r~turn springs 36 forming part of the throttle assembly 32 will act to retain the throttle valving to an "idle" position when the trigger portion of the lever 28 is released. However, if the sheathed cable 34 should bind or some other malfunction occur which prevents the throttle valving from so returning to its "idle" position upon the operator releasing the throttle control lever 28, then the valving will remain at whatever position to which it has been actuated to thus present a hazard in the event that the engine is to be started or an operator is thrown from the snowmobile lO with the throttle in a stuck open position.
Referring to Fig. 2, therein is shown an electrical engine R.P.M. control system 40 for eliminating or at least reducing the hazard just mentioned and for also reducing the possibility of engine or drive component damage as might occur as a result of a load suddenly being removed from the engine when the latter is operating at or near full throttle.
Specifically, the system 40 includes an ignition circuit comprising an alternator 42 which is driven by the engine 18 in a conventional manner for providing power through a lead 44 for firing a spark plug 46 in correspondence with the closing of a set of ignition points 48. Connected to the lead 44 is a lead 50, which contains a silicon controlled rectifier or SCR 52 that is switched, in accordance to an unsafe condition sensed by the remainder of the system 40, to connect the lead 50 to a ground lead 54 to ground out the ignition to maintain the engine speed at a safe value. ~-Forming an impor~ant part of the system 40 are a pair of identical integrated timing circuits which are indicated by the boxes 56 and 58. The circuits 56 and 58 may take many forms , . . . .
. .
hDW~Y~ ~hP C~ S ~hDS~ 2S~ h~ p~ r~ .y simila~ t~
ones su})~lied as part No. MC 14~ hy Motorola S~miconduct~:~
Products Inc. Each of the circuits 56 and 58 include a ground pin lr a trigger pin 2, an output pin 3, a reset pin 4, a control voltage pin 5, a threshold voltage pin 6, a ~ischarge volta~e pin 7, and a supply voltage pin 8. The supply voltage for driving the circuits 56 and 58 is provided by the alternator 42, which is connected to a power supply lead 60. Connected in series in the lead 60 is a rectifier diode 62 and a resistor 64. A lead 66 containing a capacitor 68 connects a junction 70, located between the diode 62 and resistor 64 with the ground lead 54 while a lead 72 containing a Zener regulator diode 74 is connected to the lead 60, after the resistor 64, and to the ground lead 54. Thus, as employed in the circuit, the diode 62, resistor 64, capacitor 68 and Zener diode 74 cooperate to provide a d.c. voltage equal to the reverse breakdown voltage of the Zener diode 74 to power the timing circuits 56 and 58. Accordingly, the power supply line 60 is connected to the supply voltage pins 8 of the circuits S6 and 58 respectively by leads 75 and 76 while the circuits 56 and 58 are respectively grounded by leads 77 and 78 connected between the ground pins 1 of the circuits and the ground lead 54. A lead : 80 is coupled to the supply line 60 ahead of the rectifier diode 62 and conveys an alternating voltage to the base of a txansistor 82 which results in the latter being turned on and off at a frequency equal to that o~ the voltage and thus at a frequency which corresponds to the engine R.P.M. A lead 84 is connected between the lead 80 and ground and contains a Zener diode 86 - which regulates the voltage in the lead 80 such that it is never negative nor exceeds the reverse breakdown voltage of the Zener diode 86.
The threshold and discharge voltage pins 6 and 7, respec-tively, of the timing circuit 56 are connected in parallel to a , ~ t~
1 lead of the timing circuit 56 are connected in parallel to a lead 90 which is connected to an emitter 92 of the transistor 82.
Thus, when the voltage in the lead 80 switches on the transistor 82, the latter conducts to connect the pins 6 and 7 to ground such as to cause a capacitor 94 to discharge, the capacitor 94 being located in a lead 96 connected between the power supply lead 60 and ground lead 54 and joined to the lead 90 at 98.
Connected in the lead 96 in series with the capacitor 94 is a resistor 100. When the capacitor 94 discharges and the transistor 82 switches off during the negative excursion of the voltage in line 80, the voltage at the pins 6 and 7 builds at a rate deter-mined by the time constant of the resistor 100 and capacitor 94, this time constant being designed to be less than the frequency of the voltage produced when the engine R.P.M. is at a value for effecting drive engagement speed but above idle speed. For example, if the engine idles at 2,000 R.P.M. and the drive 20 engages when the engine reaches 3,000 R.P.M., the time constant may be selected to correspond to a voltage frequency produced when the engine is operating between 2,400-2,500 R.P.M. Accord-20 ingly, if the engine is designed according to the example givenand is operating at some speed below 2,400 R.P.M. the frequency at which the transistor 82 is turned on and off will be suffici-ently low to permit the voltage in the lead 90 to attain a value greater than the threshold voltage of the timing circuit 56 during the time that the transistor 82 is turned off. The circuit 56 is designed such that during the time that the voltage at pin 6 is building from 0 to the threshold value the output voltage ~t pin 3 will be high, this voltage becoming low upon the threshold value of the circuit being reached. Thus, during slow R.P .M.
30 operation of the engine 18, the output voltage at pin 3 will change states at a frequency corresponding to the R.P.M. value.
_ 5 _ .: '' . - ' ` " '~ . :
, ~ : ' . . . - :
- . :
1 OI1 the other hand, should the speed of the engine 18 increase to a value above 2,400-2,500 R.P.M., the frequency at which the transistor 82 is turned on and off will be too high to permit the voltage in the lead 92 to ever attain a value greater than the threshold voltage of the circuit 56 during the time that the transistor 82 is turned off and the voltage at the output pin 3 will remain high.
The output pin 3 of the timing circuit 56 is connected by means of a lead 102, to the base of a transistor 104 having its 10 emitter 106 connected, by means of a lead 108, to the threshold and discharge pins 6 and 7 of the timing circuit 58. A lead 110, which is connected between the power supply lead 60 and ground lead 54, joins the lead 108 at 112 and connected in series in the lead 110 is a resistor 114 and capacitor 116. Anytime that the output voltage at the pin 3 is high, the transistor 104 is turned on to discharge the capacitor 116 to ground and anytime output voltage at the pin 3 is low, the transistor 104 is turned off and the voltage in the lead 108 builds at a rate determined by the time constant of the resistor 114 and the capacitor 116. This time constant is somewhat greater than that of the resistor 100 and capacitor 94 but still corresponds to an engine R.P.M. fre-quency below drive engagement speed, it being noted that the purpose of the circuit S8 is to give stability to the system to ensure that transient voltages do not efect unwanted control of the engine.
Thus, when the engine R.P.M. is below engagement speed and below that speed for producing a voltage having a frequency equal to the time constant of the resistor 100 and capacitor 94 and the output voltage at pin 3 changes from high to low at this fre-30 quency, and consequently the transistor 104 will be turned on andoff at this frequency. The time constant of the resistor 114 and capacitor 116 is sufficiently long that the threshold voltage of - -, . . . . ~: - . :
, , ~ ' " ' 1 the circult 58 is never reached and the voltage at the output pin 3 thereof remains high. However, if the R.P.M. of the snowmobile engine is equal to the preset critical limit of the circuit 56 such as to effect a constantly high output voltage at the pin 3 thereof, the transistor 104 will be constantly turned off permit ting the voltage at the pins 6 and 7 to go high resulting in the circuit 58 effecting a low voltage at its output pin.
The output pin 3 of the circuit 58 is connected, by means of a lead 118, to the base of a transistor 120 having its collector connected to the power supply lead 60 by a lead 122 and having its emitter 124 connected to ground by a lead 126. Connected between the lead 122 and the gate of the SCR 52 is a lead 128.
Whenever the output voltage at the pin 3 of the timing circuit 58 is high the transistor 120 is on and the gate voltage o the SCR
52 is low so that the latter is off. However, when the voltage at the output pin of the timing circuit 58 is low, the transistor is off and the gate voltage of the SCR 52 is high enough to gate the SCR 52 on to ground out the ignition to limit the snowmobile engine speed to a value below the critical speed.
Provided for permitting the engine to run at speeds in excess of engagement speed is circuitry including a resistor 130 connected in series with the resistor 100 by means of a lead 132 having one end connected to the power supply lead 60 and the other end connected to the lead 96. A normally open switch 134 is located in the lead 132 between the resistor 130 and power supply lead 60. The switch 134 would be located at a location convenient for actuation by the operator whenever he desired to operate the snowmobile engine at speeds above drive engagement speed. Such operation of the switch 134 changes the time constant 30 to a value equal to the product of the resistances of the resis- ~ -tor~ 100 and 134 divided by their sum and multiplied by the capacitance of the capacitor 94. Thus the time constant is .. . ~
. .
1 shortened such as to requ-re increased engine R.P.M. to effect turning on of the SCR 52. Thus a high speed limit is provided and it is selected to be just slightly below the maximum design speed o~ the engine 18 and/or drive 20. Thus, in the event that the drive belt 26 breaks or some other part of the traction drive 20 fails such as to remove the load from the engine 18 when the latter is being operated at or near full throttle, the engine ignition will be controlled to limit the speed of the engine below the maximum design speed.
10Should the operator be thrown from the snowmobile 10, the switch 134 will immediately open to automatically re-establish the lower speed limit whereby the engine ignition is controlled such as to lower the engine speed below that for effecting drive engagement.
~, - 8 ~
, . .
Claims (2)
1. In combination with a snowmobile provided with an internal combustion engine, an electrical ignition system for the engine and a speed responsive traction drive coupled to the engine for delivering torque only upon the engine reaching a predetermined speed, an electrical engine RPM control circuit including an on-off switching element coupled to the ignition circuit operative only when on for connecting the latter to ground to prevent combustion in the engine; an electrical sensor coupled to the engine and operative for sending out an electrical signal representative of the engine speed; and a timing circuitry connected between the sensor and the on-off switching elemet for turning the latter on only when the engine operates at a speed greater than an idling speed of the engine but less than said predetermined speed.
2. The combination defined in claim 1 wherein said engine R.P.M. control circuit includes normally de-energized speed limit change circuitry containing a normally off, manually operated switch which when closed energizes the speed limit change cir-cuitry such as to cause the timing circuit to operate to turn on the on-off switching element only when the engine R.P.M. has reached a predetermined value below a maximum design speed of the engine.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,346A CA1111940A (en) | 1978-02-20 | 1978-02-20 | Engine r.p.m. control system for snowmobile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,346A CA1111940A (en) | 1978-02-20 | 1978-02-20 | Engine r.p.m. control system for snowmobile |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1111940A true CA1111940A (en) | 1981-11-03 |
Family
ID=4110823
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,346A Expired CA1111940A (en) | 1978-02-20 | 1978-02-20 | Engine r.p.m. control system for snowmobile |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1111940A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114321223A (en) * | 2021-12-03 | 2022-04-12 | 武汉航空仪表有限责任公司 | Mechanical descending speed control device |
-
1978
- 1978-02-20 CA CA297,346A patent/CA1111940A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114321223A (en) * | 2021-12-03 | 2022-04-12 | 武汉航空仪表有限责任公司 | Mechanical descending speed control device |
| CN114321223B (en) * | 2021-12-03 | 2023-12-22 | 武汉航空仪表有限责任公司 | Mechanical descent speed control device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |