Ignition magneto safety interlock

Claim 2

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: first electrical circuit means for connection to a primary winding of an ignition system, including a first electronic control means having a first, second and control electrode, operative to short said winding in response to a selectively applied electrical signal to said control electrode; second control circuit means including a positionresponsive switch and also including a second electronic control means coupled between the control and second electrodes of said first electronic control means, for selectively permitting a signal to be applied or preventing a signal from being applied to the control electrode of said first electronic control means in response to the condition of the position-responsive switch or the second electronic control means or both, said second electronic control means having a first, second and control electrode and being changeable between conditions exhibiting high and low electrical impedances; and third electrical circuit means for applying an electrical signal to the control electrode of said second electronic control means to determine its condition; the electrical operation of all of said circuit means being dependent solely upon magneto-generated energy.

Claim 3

A safety interlock as set forth in claim 1 wherein said position-responsive switch is movable to a closed position to prevent a signal from being applied to the control electrode of said first electronic control means and wherein said third circuit means applies an electrical signal to change the condition of said second electronic control means only when said position-responsive switch is closed.

Claim 4

A safety interlock as set forth in claim 2 wherein said second electronic control means is in series electrically with the control electrode of said first electronic control means.

Claim 5

A safety interlock as set forth in claim 3 wherein the electrical impedance of said second electronic control means is normally low in the absence of a signal to its control electrode.

Claim 6

A safety interlock as set forth in claim 2 wherein said third circuit means includes capacitance means responsive to periodic electrical imput pulses for applying an electrIcal signal to the control electrode of said second electronic control means for sufficient time to maintain a changed condition of said second electronic control means for the interval between said periodic pulses while said engine is running.

Claim 7

A safety interlock as set forth in claim 1 wherein said third electrical circuit means includes a capacitor for applying a voltage from the primary magneto winding to said control electrode of the second electronic control means for a time interval of between 0.2 and 2 seconds.

Claim 8

An electrical system for selectively shorting a primary winding of a magneto ignition system for an internal combustion system, comprising: first circuits means including a first electronic control means for connection across said winding and controllable through a control electrode between a low impedance or conductive state and a high impedance or non-conductive state in response to a voltage signal; second circuit means for controlling the application of a voltage signal produced in said primary winding to said control electrode, including a position-responsive switch and a second electronic control means for selectively permitting a voltage signal to be applied to said control electrode; and third circuit means, including a voltage sensitive memory, for applying a control signal to said second electronic control means in response to voltage signals produced in said primary winding while said first electronic control means is maintained nonconductive, to change the conductivity of said second electronic control means from that which it exhibits in the absence of a control signal, and maintaining the changed conductivity only as long as a voltage pulse rate above a predetermined level is produced in said primary winding, thereby controlling the condition of said first electronic control means independently of said position-responsive switch when said voltage pulse rate is at said predetermined level; the electrical operation of all of said circuit means being dependent solely upon magneto-generated energy.

Claim 9

An electrical system for selectively shorting a primary winding of a magneto ignition system for an internal combustion system, comprising: first circuits means including a first electronic control means for connection across said winding and controllable through a control electrode between a low impedance or conductive state and a high impedance or non-conductive state in response to a voltage signal; second circuit means for controlling the application of a voltage signal produced in said primary winding to said control electrode, including a position-responsive switch and a second electronic control means for selectively permitting a voltage signal to be applied to said control electrode; and third circuit means, including a voltage sensitive memory, for applying a control signal to said second electronic control means in response to voltage signals produced in said primary winding while said first electronic control means is maintained nonconductive, to change the conductivity of said second electronic control means from that which it exhibits in the absence of a control signal, and maintaining the changed conductivity only as long as a voltage pulse rate above a predetermined level is produced in said primary winding, thereby controlling the condition of said first electronic control means independently of said position-responsive switch when said voltage pulse rate is at said predetermined level; the electrical operation of all of said circuit means being dependent solely upon magneto-generated energy.

Claim 10

An electrical circuit for selectively shorting only negative electrical pulses produced in a primary winding of a magneto in an ignition system of an internal combustion engine, comprising: a first electrical circuit connected to a primary winding of a magneto in an ignition system and including first electronic control means having a first, second and control electrode and operative when an electrical signal is applied to the control electrode to conduct in only one direction; a second electrical circuit connected to said winding and coupled to said control electrode for selectively controlling the conductivity of said first electronic control means; rectifier means for permitting only negative voltage pulses from said winding to be applied to said circuits; said second circuit including a position-responsive switch operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive and a second electronic control means operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive when said position-responsive switch is in a position to allow the same, both of said switch and second electronic control means being coupled between the control and second electrodes of said first electronic control means, said second electronic control means having a control electrode and being operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance in response to an electronic signal applied to its control electrode; and a third circuit means for applying an electrical signal to the control electrode of said second electronic control means, initially only when said position-responsive switch is operated to prevent said first electronic control means from being rendered conductive, to change the condition of said second electronic control means to prevent said first electronic control means from being rendered conductive notwithstanding the subsequent condition of said position responsive switch.

Claim 11

An electrical circuit for selectively shorting only negative electrical pulses produced in a primary winding of a magneto in an ignition system of an internal combustion engine, comprising: a first electrical circuit connected to a primary winding of a magneto in an ignition system and including first electronic control means having a first, second and control electrode and operative when an electrical signal is applied to the control electrode to conduct in only one direction; a second electrical circuit connected to said winding and coupled to said control electrode for selectively controlling the conductivity of said first electronic control means; rectifier means for permitting only negative voltage pulses from said winding to be applied to said circuits; said second circuit including a position-responsive switch operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive and a second electronic control means operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive when said position-responsive switch is in a position to allow the same, both of said switch and second electronic control means being coupled between the control and second electrodes of said first electronic control means, said second electronic control means having a control electrode and being operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance in response to an electronic signal applied to its control electrode; and a third circuit means for applying an electrical signal to the control electrode of said second electronic control means, initially only when said position-responsive switch is operated to prevent said first electronic control means from being rendered conductive, to change the condition of said second electronic control means to prevent said first electronic control means from being rendered conductive notwithstanding the subsequent condition of said position responsive switch.

Claim 12

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition, said interlock comprising: first electrical circuit means for connection to a primary winding of an ignition system, including a first electronic control means having a first, second and control electrode, operative to short said winding in response to a selectively applied electrical signal to said control electrode; second electrical control circuit means including a position-responsive switch and also including a second electronic control means coupled between the control and second electrodes of said first electronic control means, for selectively permitting a signal to be applied to the control electrode of said first electronic control means in response to one condition of the position-responsive switch and one condition of the second electronic control means, said second electronic control means having a first, second and control electrode and conditions exhibiting high and low electrical impedances, dependent upon an electrical signal at the control electrode; and third electrical circuit means for applying a signal to the control electrode of said second electronic control means to determine its condition.

Claim 13

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition, said interlock comprising: first electrical circuit means for connection to a primary winding of an ignition system, including a first electronic control means having a first, second and control electrode, operative to short said winding in response to a selectively applied electrical signal to said control electrode; second electrical control circuit means including a position-responsive switch and also including a second electronic control means coupled between the control and second electrodes of said first electronic control means, for selectively permitting a signal to be applied to the control electrode of said first electronic control means in response to one condition of the position-responsive switch and one condition of the second electronic control means, said second electronic control means having a first, second and control electrode and conditions exhibiting high and low electrical impedances, dependent upon an electrical signal at the control electrode; and third electrical circuit means for applying a signal to the control electrode of said second electronic control means to determine its condition.

Claim 14

A magneto safety interlock for controlling the starting of an internal combustion engine that has a magneto primary winding that can be shorted to prevent ignition, said interlock comprising: means, including a circuit adapted to be connected electrically to a primary winding of a magneto, to selectively short the winding, said circuit including a switch electrically operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance and when connected across said winding necessarily shorts the winding when the switch is in a low impedance condition; and an electrical control circuit coupled to said switch and adapted to be connected electrically to said winding for selectively changing said switch from a condition exhibiting a high electrical impedance to a condition exhibiting a low electrical impedance, including connections for electrically coupling a position-responsive switch that, when closed, prevents the condition of said electrically-operable switch from being so changed; and electrical circuit means coupled to said electrically operable switch to prevent the condition of said electrically operable switch from being changed in response to opening said position-responsive switch when electrical pulses are being generated by said winding; the electrical operation of said interlock being dependent solely upon magneto-generated energy.

Claim 15

A magneto safety interlock for controlling the starting of an internal combustion engine that has a magneto primary winding that can be shorted to prevent ignition, said interlock comprising: means, including a circuit adapted to be connected electrically to a primary winding of a magneto, to selectively short the winding, said circuit including a switch electrically operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance and when connected across said winding necessarily shorts the winding when the switch is in a low impedance condition; and an electrical control circuit coupled to said switch and adapted to be connected electrically to said winding for selectively changing said switch from a condition exhibiting a high electrical impedance to a condition exhibiting a low electrical impedance, including connections for electrically coupling a position-responsive switch that, when closed, prevents the condition of said electrically-operable switch from being so changed; and electrical circuit means coupled to said electrically operable switch to prevent the condition of said electrically operable switch from being changed in response to opening said position-responsive switch when electrical pulses are being generated by said winding; the electrical operation of said interlock being dependent solely upon magneto-generated energy.

Claim 16

A magneto safety interlock for controlling the starting of an internal combustion engine that has a magneto primary winding that can be shorted to prevent ignition, said interlock comprising: means, including a circuit adapted to be connected electrically to a primary winding of a magneto, to selectively short the winding, said circuit including a switch electrically operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance and when connected across said winding necessarily shorts the winding when the switch is in a low impedance condition; and an electrical control circuit, including an electronic control device, coupled to said switch and adapted to be connected electrically to said winding for selectively changing said switch from a condition exhibiting a high electrical impedance to a condition exhibiting a low electrical impedance, and further including connections for electrically coupling a position-responsive switch that, when closed, prevents the condition of said electrically operable switch from being so changed; and electrical circuit means coupled to said electrically operable switch for affecting the condition of the electronic control device to prevent the condition of said electrically operable switch from being changed in response to opening said position-responsive switch when electrical pulses are being generated by said winding; the electrical operation of said interlock being dependent solely upon magneto-generated energy.

Claim 17

A magneto safety interlock for controlling the starting of an internal combustion engine that has a magneto primary winding that can be shorted to prevent ignition, said interlock comprising: means, including a circuit adapted to be connected electrically to a primary winding of a magneto, to selectively short the winding, said circuit including a switch electrically operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance and when connected across said winding necessarily shorts the winding when the switch is in a low impedance condition; and an electrical control circuit, including an electronic control device, coupled to said switch and adapted to be connected electrically to said winding for selectively changing said switch from a condition exhibiting a high electrical impedance to a condition exhibiting a low electrical impedance, and further including connections for electrically coupling a position-responsive switch that, when closed, prevents the condition of said electrically operable switch from being so changed; and electrical circuit means coupled to said electrically operable switch for affecting the condition of the electronic control device to prevent the condition of said electrically operable switch from being changed in response to opening said position-responsive switch when electrical pulses are being generated by said winding; the electrical operation of said interlock being dependent solely upon magneto-generated energy.

Claim 18

A high impedance electrical circuit for use with a magneto ignition system of an internal combustion engine and an associated drive transmission to selectively short a primary winding of the magneto ignition system to prevent starting of the engine in response to a predetermined condition of the drive transmission associated with the engine, the condition and operation of said circuit being in part responsive to spark producing voltage pulses produced by said magneto ignition system; said circuit, when electrically coupled across a primary magneto winding, being electrically associated therwith in the following manner, dependent in operation solely upon magneto-generated energy, and including: coupling means for electrically connecting said circuit to a primary winding of a magneto ignition system and to a mechanically actuatable switch; a silicon controlled rectifier having first, second and control electrodes, being normally non-conductive in the absence of a voltage signal applied to the control electrode, and connected to said coupling means for being electrically connected across the primary winding of a magneto ignition system; a transistor having first, second and control electrodes, adapted to be switched by a voltage applied to its control electrode between conductive and non-conductive conditions, one of which is its normal condition prior to operation of energization of the circuit, electrically connected to the control electrode of the silicon controlled rectifier and electrically connected to said coupling means for connection to said primary winding and said switch, and operable in its conductive condition to electrically couple said control electrode of the silicon controlled rectifier to said coupling means and hence to said primary winding in use; and means, including a capacitor electrically connected to said coupling means to be chargeable by spark-producing pulses from said primary coil in use, for applying and maintaining a voltage at the control electrode of the transistor of a magnitude and duration to maintain a switched condition of said transistor from its normal condition prior to operation or energization of said circuit, as long as the frequency of said spark-producing voltage pulses is above a predetermined level, not less than one every two seconds, thereby controlling the condition of said silicon controlled rectifier independently of an electrical connection across said coupling means for connecting said circuit to a mechanically actuatable switch.

Claim 19

A high impedance electrical circuit for use with a magneto ignition system of an internal combustion engine and an associated drive transmission to selectively short a primary winding of the magneto ignition system to prevent starting of the engine in response to a predetermined condition of the drive transmission associated with the engine, the condition and operation of said circuit being in part responsive to spark producing voltage pulses produced by said magneto ignition system; said circuit, when electrically coupled across a primary magneto winding, being electrically associated therwith in the following manner, dependent in operation solely upon magneto-generated energy, and including: coupling means for electrically connecting said circuit to a primary winding of a magneto ignition system and to a mechanically actuatable switch; a silicon controlled rectifier having first, second and control electrodes, being normally non-conductive in the absence of a voltage signal applied to the control electrode, and connected to said coupling means for being electrically connected across the primary winding of a magneto ignition system; a transistor having first, second and control electrodes, adapted to be switched by a voltage applied to its control electrode between conductive and non-conductive conditions, one of which is its normal condition prior to operation of energization of the circuit, electrically connected to the control electrode of the silicon controlled rectifier and electrically connected to said coupling means for connection to said primary winding and said switch, and operable in its conductive condition to electrically couple said control electrode of the silicon controlled rectifier to said coupling means and hence to said primary winding in use; and means, including a capacitor electrically connected to said coupling means to be chargeable by spark-producing pulses from said primary coil in use, for applying and maintaining a voltage at the control electrode of the transistor of a magnitude and duration to maintain a switched condition of said transistor from its normal condition prior to operation or energization of said circuit, as long as the frequency of said spark-producing voltage pulses is above a predetermined level, not less than one every two seconds, thereby controlling the condition of said silicon controlled rectifier independently of an electrical connection across said coupling means for connecting said circuit to a mechanically actuatable switch.

Claim 20

In combination, an internal combustion engine with a magneto ignition system that has a primary winding that can be shorted to prevent ignition, a manually shiftable drive transmission connected to said engine, a position responsive safety switch connected to and operated by said transmission, and an ignition interlock for controlling the starting of the internal combustion engine, said interlock being dependent in operation solely upon magneto-generated energy and comprising: first circuit means including a first electronic control means connected across said winding and controllable through a control electrode between a low impedance or conductive state and a high impedance or nonconductive state in response to a voltage signal; second circuit means for controlling the application of a voltage signal produced in said primary winding to said control electrode, including said position-responsive switch and a second electronic control means for selectively permitting a voltage signal to be applied to said control electrode; and third circuit means, including a voltage sensitive memory, for applying a signal to said second electronic control means and affectiNg the conductivity thereof as long as a voltage pulse rate above a predetermined level is produced in said primary winding, thereby controlling the condition of said first electronic control means independently of said position-responsive switch when said voltage pulse rate is at said predetermined level.

Claim 21

In combination, an internal combustion engine with a magneto ignition system that has a primary winding that can be shorted to prevent ignition, a manually shiftable drive transmission connected to said engine, a position responsive safety switch connected to and operated by said transmission, and an ignition interlock for controlling the starting of the internal combustion engine, said interlock being dependent in operation solely upon magneto-generated energy and comprising: first circuit means including a first electronic control means connected across said winding and controllable through a control electrode between a low impedance or conductive state and a high impedance or nonconductive state in response to a voltage signal; second circuit means for controlling the application of a voltage signal produced in said primary winding to said control electrode, including said position-responsive switch and a second electronic control means for selectively permitting a voltage signal to be applied to said control electrode; and third circuit means, including a voltage sensitive memory, for applying a signal to said second electronic control means and affectiNg the conductivity thereof as long as a voltage pulse rate above a predetermined level is produced in said primary winding, thereby controlling the condition of said first electronic control means independently of said position-responsive switch when said voltage pulse rate is at said predetermined level.

Claim 22

A magneto safety interlock for controlling the starting of an internal combustion engine that has a magneto primary winding that can be shorted to prevent ignition, said interlock comprising: means, including a circuit adapted to be connected electrically to a primary winding of a magneto, to selectively short the winding, said circuit including an electronic switch electrically operable through a control electrode between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance; and a control circuit coupled to said switch and adapted to be connected electrically to said winding for selectively changing said switch from a condition exhibiting a high electrical impedance to a condition exhibiting a low electrical impedance, including a position-responsive switch that, when closed, prevents the condition of said electrically-operable switch from being so changed; and electrical circuit means coupled to said electrically operable switch to prevent the condition of said electrically operable switch from being changed in response to opening said position-responsive switch when electrical pulses are being generated by said winding, said circuit means including a capacitor and serving to selectively isolate the control electrode of said electrically operable switch from positive pulses from said magneto primary winding; the electrical operation of said circuits and said electrical circuit means being dependent solely upon magneto-generated energy.

Claim 23

A magneto safety interlock for controlling the starting of an internal combustion engine that has a magneto primary winding that can be shorted to prevent ignition, said interlock comprising: means, including a circuit adapted to be connected electrically to a primary winding of a magneto, to selectively short the winding, said circuit including an electronic switch electrically operable through a control electrode between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance; and a control circuit coupled to said switch and adapted to be connected electrically to said winding for selectively changing said switch from a condition exhibiting a high electrical impedance to a condition exhibiting a low electrical impedance, including a position-responsive switch that, when closed, prevents the condition of said electrically-operable switch from being so changed; and electrical circuit means coupled to said electrically operable switch to prevent the condition of said electrically operable switch from being changed in response to opening said position-responsive switch when electrical pulses are being generated by said winding, said circuit means including a capacitor and serving to selectively isolate the control electrode of said electrically operable switch from positive pulses from said magneto primary winding; the electrical operation of said circuits and said electrical circuit means being dependent solely upon magneto-generated energy.

Claim 24

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: a first electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a mechanically actuated switch and a second electronic control means, both electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a first condition that prevents an electrical potential from being applied to said control electrode and a second condition that does not prevent an electrical potential from being applied to said control electrode, and said second electronic control means having a condition in which it does not prevent an electrical potential from being applied to said control electrode, and a condition responsive to running of the engine in which it prevents an electrical potential from being applied to said control electrode; and circuit means electrically connected to the primary winding and the second electronic control means, responsive to electrical pulses generated through said ignition system by the running of the engine, to apply an electrical potential to a control electrode of said second electronic control means to establish the condition of said second electronic control means in which it prevents an electrical input to the control electrode of said first electronic control means, whereby a change from said first condition of said switch subsequent to the starting of said engine will not render said first electronic control means conductive.

Claim 25

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: a first electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a mechanically actuated switch and a second electronic control means, both electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a first condition that prevents an electrical potential from being applied to said control electrode and a second condition that does not prevent an electrical potential from being applied to said control electrode, and said second electronic control means having a condition in which it does not prevent an electrical potential from being applied to said control electrode, and a condition responsive to running of the engine in which it prevents an electrical potential from being applied to said control electrode; and circuit means electrically connected to the primary winding and the second electronic control means, responsive to electrical pulses generated through said ignition system by the running of the engine, to apply an electrical potential to a control electrode of said second electronic control means to establish the condition of said second electronic control means in which it prevents an electrical input to the control electrode of said first electronic control means, whereby a change from said first condition of said switch subsequent to the starting of said engine will not render said first electronic control means conductive.

Claim 26

A safety interlock as set forth in claim 16 wherein said second electronic control means is in series electrically with the control electrode of said first electronic control means.

Claim 27

A safety interlock as set forth in claim 17 wherein the electrical impedance of said second electronic control means is normally low in the absence of a signal to its control electrode.

Claim 28

A safety Interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: A first electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a mechanically actuated switch and a second electronic control means, both electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a closed condition that prevents an electrical potential from being applied to said control electrode and an open condition that does not prevent an electrical potential from being applied to said control electrode, and said second electronic control means having a condition in which it does not prevent an electrical potential from being applied to said control electrode, and a condition responsive to running of the engine in which it prevents an electrical potential from being applied to said control electrode; and circuit means electrically connected to the primary winding and the second electronic control means, responsive to electrical pulses generated through said ignition system by the running of the engine, to apply an electrical potential to a control electrode of said second electronic control means to establish the condition of said second electronic control means in which it prevents an electrical input to the control electrode of said first electronic control means, whereby an opening of said switch subsequent to the starting of said engine will not render said first electronic control means conductive.

Claim 29

A safety Interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: A first electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a mechanically actuated switch and a second electronic control means, both electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a closed condition that prevents an electrical potential from being applied to said control electrode and an open condition that does not prevent an electrical potential from being applied to said control electrode, and said second electronic control means having a condition in which it does not prevent an electrical potential from being applied to said control electrode, and a condition responsive to running of the engine in which it prevents an electrical potential from being applied to said control electrode; and circuit means electrically connected to the primary winding and the second electronic control means, responsive to electrical pulses generated through said ignition system by the running of the engine, to apply an electrical potential to a control electrode of said second electronic control means to establish the condition of said second electronic control means in which it prevents an electrical input to the control electrode of said first electronic control means, whereby an opening of said switch subsequent to the starting of said engine will not render said first electronic control means conductive.

Claim 30

A safety interlock as set forth in claim 19 wherein said circuit means includes capacitance means responsive to periodic electrical input pulses for applying an electrical signal to the control electrode of said second electronic control means for sufficient time to maintain a changed condition of said second electronic control means for the interval between said periodic pulses while said engine is running.

Claim 31

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: a first electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a mechanically actuated switch and a second electronic control means, both electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a first condition that prevents an electrical potential from being applied to said control electrode and a second condition that does not prevent an electrical potential from being applied to said control electrode, and said second electronic control means having a condition in which it does not prevent an electrical potential from being applied to said control electrode, and a condition responsive to running of the engine in which it prevents an electrical potential from being applied to said control electrode; and circuit means electrically connected to the second electronic control means, responsive to the running of the engine, to apply an electrical potential to a control electrode of said second electronic control means to establish the condition of said second electronic control means in which it prevents an electrical input to the control electrode of said first electronic control means, whereby a change from said first condition of said switch subsequent to the starting of said engine will not render said first electronic control means conductive.

Claim 32

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: a first electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a mechanically actuated switch and a second electronic control means, both electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a first condition that prevents an electrical potential from being applied to said control electrode and a second condition that does not prevent an electrical potential from being applied to said control electrode, and said second electronic control means having a condition in which it does not prevent an electrical potential from being applied to said control electrode, and a condition responsive to running of the engine in which it prevents an electrical potential from being applied to said control electrode; and circuit means electrically connected to the second electronic control means, responsive to the running of the engine, to apply an electrical potential to a control electrode of said second electronic control means to establish the condition of said second electronic control means in which it prevents an electrical input to the control electrode of said first electronic control means, whereby a change from said first condition of said switch subsequent to the starting of said engine will not render said first electronic control means conductive.

Claim 33

A safety interlock for controlling the starting of an internal combustion engine that Has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: a circuit to be electrically connected across a primary winding of an ignition system and connected to contacts of a position responsive switch that in a first condition permits a potential to be maintained across the primary winding so that the engine can be started and in a second condition prior to the starting of the engine prevents such a potential from being maintained; said circuit including: a first electronic control means, with first, second and control electrodes, that is nonconductive until a gating signal is applied to the control electrode, and that when connected across the primary winding of an ignition system and when conductive, will short the winding to prevent the ignition from firing; a second electronic control means with first, second and control electrodes, and a conductive and nonconductive condition dependent upon the presence or absence of an electrical signal at the control electrode, which signal originates from said primary winding, said second electronic control means in one said condition permitting a gating signal to be effectively applied to the control electrode of said first electronic control means, said gating signal originating from the primary winding when the position responsive switch is in said second condition, and said second electronic control means preventing a gating signal from being effectively applied to the control electrode of said first electronic control means when said second electronic control means is in the other of said conditions, regardless of the condition of said position responsive switch; and means, coupled between said primary winding and the control electrode of said second electronic control means, responsive to electrical pulses from said primary winding, to apply an electrical signal to said last-mentioned control electrode to change the condition of said second electronic control means after the engine has started and to maintain a signal as long as said electrical pulses occur at a predetermined minimum frequency, thereby preventing a gating signal from being applied at the control electrode of said first electronic control means when said position responsive switch is changed to said second condition.

Claim 34

A safety interlock for controlling the starting of an internal combustion engine that Has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: a circuit to be electrically connected across a primary winding of an ignition system and connected to contacts of a position responsive switch that in a first condition permits a potential to be maintained across the primary winding so that the engine can be started and in a second condition prior to the starting of the engine prevents such a potential from being maintained; said circuit including: a first electronic control means, with first, second and control electrodes, that is nonconductive until a gating signal is applied to the control electrode, and that when connected across the primary winding of an ignition system and when conductive, will short the winding to prevent the ignition from firing; a second electronic control means with first, second and control electrodes, and a conductive and nonconductive condition dependent upon the presence or absence of an electrical signal at the control electrode, which signal originates from said primary winding, said second electronic control means in one said condition permitting a gating signal to be effectively applied to the control electrode of said first electronic control means, said gating signal originating from the primary winding when the position responsive switch is in said second condition, and said second electronic control means preventing a gating signal from being effectively applied to the control electrode of said first electronic control means when said second electronic control means is in the other of said conditions, regardless of the condition of said position responsive switch; and means, coupled between said primary winding and the control electrode of said second electronic control means, responsive to electrical pulses from said primary winding, to apply an electrical signal to said last-mentioned control electrode to change the condition of said second electronic control means after the engine has started and to maintain a signal as long as said electrical pulses occur at a predetermined minimum frequency, thereby preventing a gating signal from being applied at the control electrode of said first electronic control means when said position responsive switch is changed to said second condition.

Claim 35

A magneto safety interlock for an engine ignition system, including a silicon controlled rectifier for connection across a primary magneto winding of an engine ignition system, said silicon controlled rectifier being normally nonconductive and which when conductive serves to electrically short said winding; first electrical circuit means coupled to a control electrode or gate of said silicon controlled rectifier and for connection to a position responsive switch and also across said primary winding for changing the conductive condition of said silicon controlled rectifier in response to the conductive condition of said switch; and second electrical circuit means coupled to said control electrode or gate, responsive to running of said engine, for preventing the conductive condition of said silicon controlled rectifier from being changed in response to the conductive condition of said switch after said engine is running.

Claim 36

A magneto safety interlock for an engine ignition system, including a silicon controlled rectifier for connection across a primary magneto winding of an engine ignition system, said silicon controlled rectifier being normally nonconductive and which when conductive serves to electrically short said winding; first electrical circuit means coupled to a control electrode or gate of said silicon controlled rectifier and for connection to a position responsive switch and also across said primary winding for changing the conductive condition of said silicon controlled rectifier in response to the conductive condition of said switch; and second electrical circuit means coupled to said control electrode or gate, responsive to running of said engine, for preventing the conductive condition of said silicon controlled rectifier from being changed in response to the conductive condition of said switch after said engine is running.

Claim 37

A magneto safety interlock for selectively shorting electrical pulses only of a polarity used for ignition and produced in a primary winding of a magneto in an ignition system of an internal combustion engine, comprising: a silicon controlled rectifier for connection across a primary magneto winding of an engine ignition system, said silicon controlled rectifier being normally nonconductive and having a gate electrode that renders said silicon controlled rectifier conductive in response to an electrical signal; and electrical circuit means coupled to said silicon controlled rectifier, including (a) rectifier means for permitting the passage through said circuit means of only electrical pulses of the polarity used for firing said engine, (b) means for coupling said Gate electrode to said winding through a position-responsive switch that permits or prevents the change of the conductive condition of said silicon controlled rectifier in response to an electrical pulse prior to the running of the engine, depending upon the condition of said switch, and (c) capacitor means responsive to electrical pulses from said primary winding after the engine is running for preventing said silicon controlled rectifier from being rendered conductive by a condition of said position responsive switch.

Claim 38

A magneto safety interlock for selectively shorting electrical pulses only of a polarity used for ignition and produced in a primary winding of a magneto in an ignition system of an internal combustion engine, comprising: a silicon controlled rectifier for connection across a primary magneto winding of an engine ignition system, said silicon controlled rectifier being normally nonconductive and having a gate electrode that renders said silicon controlled rectifier conductive in response to an electrical signal; and electrical circuit means coupled to said silicon controlled rectifier, including (a) rectifier means for permitting the passage through said circuit means of only electrical pulses of the polarity used for firing said engine, (b) means for coupling said Gate electrode to said winding through a position-responsive switch that permits or prevents the change of the conductive condition of said silicon controlled rectifier in response to an electrical pulse prior to the running of the engine, depending upon the condition of said switch, and (c) capacitor means responsive to electrical pulses from said primary winding after the engine is running for preventing said silicon controlled rectifier from being rendered conductive by a condition of said position responsive switch.

Claim 39

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: an electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a control circuit including a mechanically actuated switch electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a closed condition that prevents an electrical potential from being applied to said control electrode and an open condition that does not prevent an electrical potential from being applied to said control electrode; and circuit means responsive to running of the engine to prevent an electrical input from being applied to the control electrode of said electronic control means, whereby an opening of said switch subsequent to the starting of said engine will not render said electronic control means conductive.

Claim 40

A safety interlock for controlling the starting of an internal combustion engine that has a magneto ignition system with a primary winding that can be shorted to prevent ignition; said interlock comprising: an electronic control means electrically connected across a primary winding of an ignition system, normally non-conductive and rendered conductive by an electrical potential applied to a control electrode thereof; a control circuit including a mechanically actuated switch electrically coupled to the primary winding and to the first electronic control means to control the electrical potential at said control electrode, said switch having a closed condition that prevents an electrical potential from being applied to said control electrode and an open condition that does not prevent an electrical potential from being applied to said control electrode; and circuit means responsive to running of the engine to prevent an electrical input from being applied to the control electrode of said electronic control means, whereby an opening of said switch subsequent to the starting of said engine will not render said electronic control means conductive.

Claim 41

A safety interlock as set forth in claim 25 wherein said circuit means includes a capacitor coupled between said primary winding and said control electrode, charged by pulses generated through said primary winding, for preventing an electrical input to the control electrode of said electronic control means when said engine is running.

Claim 42

An electrical circuit for selectively shorting only negative electrical pulses produced in a primary winding of a magneto in an ignition system of an internal combustion engine, comprising: a first electrical circuit connected to a primary winding of a magneto in an ignition system and including first electronic control means having a first, second and control electrode and operative when an electrical signal is applied to the control electrode to conduct in only one direction; a second electrical circuit connected to said winding and coupled to said control electrode for selectively controlling the conductivity of said first electronic control means; rectifier means for permitting only negative voltage pulses from said winding to be applied to said circuits; said second circuit including a position-responsive switch operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive and a second electronic control means operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive when said position-responsive switch is in a position to allow the first electronic control means to be rendered conductive, said second electronic control means having a control electrode and being operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance in response to an electronic signal applied to its control electrode; and a third circuit means for applying an electrical signal to the control electrode of said second electronic control means, initially only when said position-responsive switch is operated to prevent said first electronic control means from being rendered conductive, to change the condition of said second electronic control means from that condition it exhibits in the absence of a signal applied to its control electrode to prevent said first electronic control means from being rendered conductive notwithstanding the subsequEnt condition of said position responsive switch.

Claim 43

An electrical circuit for selectively shorting only negative electrical pulses produced in a primary winding of a magneto in an ignition system of an internal combustion engine, comprising: a first electrical circuit connected to a primary winding of a magneto in an ignition system and including first electronic control means having a first, second and control electrode and operative when an electrical signal is applied to the control electrode to conduct in only one direction; a second electrical circuit connected to said winding and coupled to said control electrode for selectively controlling the conductivity of said first electronic control means; rectifier means for permitting only negative voltage pulses from said winding to be applied to said circuits; said second circuit including a position-responsive switch operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive and a second electronic control means operable to selectively prevent or allow said first electronic control means from being or to be rendered conductive when said position-responsive switch is in a position to allow the first electronic control means to be rendered conductive, said second electronic control means having a control electrode and being operable between a condition exhibiting high electrical impedance and a condition exhibiting low electrical impedance in response to an electronic signal applied to its control electrode; and a third circuit means for applying an electrical signal to the control electrode of said second electronic control means, initially only when said position-responsive switch is operated to prevent said first electronic control means from being rendered conductive, to change the condition of said second electronic control means from that condition it exhibits in the absence of a signal applied to its control electrode to prevent said first electronic control means from being rendered conductive notwithstanding the subsequEnt condition of said position responsive switch.