Safety device for controlling an ignition circuit

A safety device for controlling an ignition circuit for an internal combustion engine associated with a transmission coupling the engine to a load, the ignition circuit comprising a power supply and a discharge control circuit including at least one ignition coil having a primary and a secondary winding producing a high voltage to fire a spark plug provided in the engine, a capacitor adapted to be charged by the power supply, and a semiconductor switch for discharging said capacitor through a primary winding of the ignition coil, said safety device coupled between the power supply and the discharge control circuit and comprising:

• a thyristor connected between the power supply and the discharge control circuit so as to permit the ignition circuit to produce the high voltage only when said thyristor is conductive,
• a position-responsive switch,
• resistor means connecting said switch across the anode and the gate of said thyristor to permit application of a trigger signal from said power supply to the gate of said thyristor only when the transmission is in neutral, and
• a capacitor connected through said resistor means across the gate and the cathode of said thyristor to be charged by a voltage drop across the gate and the cathode of said thyristor and to provide a trigger signal to the gate of said thyristor,
• whereby once said capacitor is charged it maintains a condition wherein said thyristor is turned on whenever said thyristor is positively biased even after the transmission is shifted into gear.

A safety device for controlling an ignition circuit for an internal combustion engine associated with a transmission coupling the engine to a load, the ignition circuit including a DC supply, at least one ignition coil having a primary and a secondary winding producing a high voltage to fire a spark plug provided in the engine, and a breaker connected in series with said primary winding of the ignition coil, said safety device coupled between said DC supply and the series circuit of the primary winding and the breaker, and comprising:

• a thyristor connected between the DC supply and the series circuit of the primary winding and the breaker so as to permit the ignition circuit to produce the high voltage only when said thyristor is conductive,
• a position-responsive switch,
• resistor means connecting said switch across the anode and the gate of said thyristor to permit application of a trigger signal from said DC supply to the gate and the cathode of said thyristor only when the transmission is in neutral, and
• a capacitor connected through said resistor means across the gate and the cathode of said thyristor to be charged by a voltage drop across the gate and the cathode of said thyristor and to provide a trigger signal to the gate of said thyristor,
• whereby once said capacitor is charged it maintains a condition wherein said thyristor is turned on whenever said breaker closes in time with the rotation of the engine even after the transmission is shifted into gear.

A safety device for controlling an ignition circuit for an internal combustion engine associated with a transmission coupling the engine to a load, the ignition circuit including at least one ignition coil having a primary winding disposed in a generator by the engine and serving as a power supply and having a secondary winding, and a breaker connected across said primary winding,

• said safety device coupled between the primary winding and the breaker and comprising:
• a thyristor connected between the primary winding and the breaker so as to permit the ignition circuit to produce the high voltage only when said thyristor is conductive,
• a position-responsive switch,
• resistor means connecting said switch across the anode and the gate of said thyristor to permit application of a trigger signal from said primary winding of the ignition coil to the gate of said thyristor only when the transmission is in neutral, and
• a capacitor connected through said resistor means across the gate and the cathode of said thyristor to be charged by a voltage drop across the gate and the cathode of said thyristor and to provide a trigger signal to the gate of said thyristor,
• whereby once said capacitor is charged it maintains a condition wherein said thyristor is turned on whenever said thyristor is positively biased and said breaker closes in time with the rotation of the engine even after the transmission is shifted into gear.