Ignition system with hazardous-start inhibiting interlock

• US 4,033,311 A
• Filed: 12/26/1974
• Issued: 07/05/1977
• Est. Priority Date: 12/26/1974
• Status: Expired due to Term

• Current Assignee: R.E. Phelon Company, Inc.
• Original Assignee: R.E. Phelon Company, Inc.
• Inventors: Burson, Bob O.
• Primary Examiner(s): Dority, Jr., Carroll B.
• Assistant Examiner(s): Devinsky, Paul
• Application Number:
  US05/536,597
• Time in Patent Office: 922 Days
• Field of Search: 123/179 K, 123/198 D, 180/103 R
• US Class Current: 477/99
• CPC Class Codes: B60K 28/00 Safety devices for propulsion-unit control, specially adapted for, or arranged in, vehicles, e.g. preventing fuel supply or ignition in the event of potentially dangerous conditions for electrically-propelled vehicles B60L3/00; road vehicle drive control systems for purposes not related to the control of a particular sub-unit B60W30/00; drive control systems specially adapted for autonomous road vehicles B60W60/00
• CPC Class Codes: B60K 28/10 responsive to conditions relating to the vehicle
• CPC Class Codes: F02P 11/04 Preventing unauthorised use of engines of vehicles B60R25/04; ignition locks H01H27/00

Abstract

An ignition system of an internal combustion engine is provided with a hazardous-start inhibiting interlock that prevents the engine from being started unless an associated engine clutch, transmission, brake or similar device is placed in a safe condition for starting. The ignition system has a spark plug, a secondary winding of an ignition transformer connected to the plug to provide a sparking potential and a source of low-tension current pulses supplied to the primary winding of the ignition transformer in timed relationship with the engine cycle. The hazaradous-start inhibiting interlock is connected between the pulse source and the primary winding of the ignition transformer, and at the time of engine starting the interlock blocks the flow of current pulses to the primary winding unless the clutch, transmission or other device is safely positioned so that the vehicle or other mechanisms powered by the engine cannot be set in motion. The inhibiting interlock comprises one or more serially connected safety switches which are closed to transmit pulses from the source only when the clutch, transmission or other device is in its safe condition. If any one of these safety switches is open, engine starting is inhibited. A silicon controlled rectifier (SCR) is connected in parallel with the safety switches to maintain the transmission of pulses after the engine powered device is placed in operation and the safety switches are open. The SCR is made responsive to current pulses transmitted through the primary winding of the ignition transformer and is held in its conductive state after starting by an RC circuit having a capacitor that is charged by the current pulses. When the engine is shut off, the capacitor discharges and the SCR returns to its non-conductive state inhibiting another engine start until the safety switches are again closed by placing the associated clutch or other device in a safe starting condition.

Claims

1. An ignition system for an internal combustion engine connected in driving relationship with at least one device having a member movable between a safe position for engine starting and an unsafe position for engine starting comprising:

a spark plug for the internal combustion engine;

an ignition transformer including a low tension primary and a high tension secondary winding connected with the spark plug for producing a sparking potential to fire the plug;

a source of low tension current pulses supplied in timed relationship with the engine cycle; and

an interlock connected between the source and the primary winding of the ignition transformer for controlling the transmission of current pulses from the source to the primary winding, the interlock comprising;

a first circuit path between the source and the primary winding having a first switch operably connected with the movable member and placing the first circuit in a pulse-transmitting condition when the movable member is in the safe position and a non-transmitting condition when the member is in the unsafe position;

a second circuit path parallel with the first path between the source and the primary winding and having a second switch with a control element operable to change the second switch and second circuit path between a nontransmitting condition and a transmitting condition for the pulses independently of the movable member and the first switch; and

actuating means connected with the first and second circuit paths and with the control element of the second switch and having a pulse sensing circuit including a capacitor receiving and charged by current pulses transmitted by the first and second circuit paths to the primary winding for placing the second switch in the transmitting condition to transmit further pulses to the primary winding and including release means having a resistive means for discharging the capacitor and permitting the second switch to return to the non-transmitting condition in the absence of further current pulses.

2. An ignition system for internal combustion engines as defined in claim 1 wherein:

the first switch in the interlock is a mechanical switch; and

the second switch in the interlock is an electronic switch.

3. An ignition system as defined in claim 1 wherein:

the second switch is an electronic switch in which the control element is a control terminal for setting the switch in the conductive condition; and

the capacitor and resistive means in the pulse sensing circuit are connected with the control terminal of the second switch to control switch conduction.

4. An ignition system as defined in claim 3 wherein the second switch is a silicon controlled rectifier having the anode and cathode in the second circuit path and the gate as the control terminal connected with the capacitor and resistive means.

5. An ignition system for an internal combustion engine as defined in claim 1 wherein the ignition transformer, the second circuit path and the actuating means are mounted together in a single potted module.

6. An ignition system for an internal combustion engine as defined in claim 1 wherein the source of low tension current pulses is a low-tension magneto system.

7. An ignition system for an internal combustion engine as defined in claim 1 wherein the source of low tension current pulses is a capacitive-discharge system.

8. An ignition system for an internal combustion engine as defined in claim 1 wherein the RC circuit includes a diode connected to receive the ignition pulses;

and charge the capacitor independently of the resistive means; and

the electrically controlled switch is an electronic switch having a control terminal connected with the RC circuit for charging the switch between the conductive and non-conductive conditions.

9. In combination in a system having an internal combustion engine and a member movable between a safe position for engine starting and an unsafe position, the engine operation being supported by a source supplying ignition pulses to the primary winding of an ignition transformer, the improvement comprising:

an ignition interlock connected between the source of ignition pulses and the primary winding to selectively disconnect the source and the winding and thereby inhibit engine starting including;

a first circuit for transmitting the ignition pulses between the source and the primary winding and having a first safety switch in the circuit operable between an open condition preventing the transmission of ignition pulses from the source to the primary winding and a closed position permitting the transmission of ignition pulses to the primary winding, the switch being connected with the movable member and placed in the open position when the member is in the unsafe position and placed in the closed position when the member is in the safe position,

a second circuit in parallel with the first and having an electrically controlled second switch operable between a pulse-transmitting condition and a non-transmitting condition, and

electrical control means connected in controlling relationship with the electrically controlled switch and having an RC circuit with a switch-controlling capacitor charged by the ignition pulses transmitted through the first and second circuits for holding the second switch in the pulsetransmitting condition at and above idle speed of the engine and a resistor connected to discharge the capacitor at pulse connected to discharge the capacitor at pulse rates below idle speed to release the second switch from the transmitting to the non-transmitting condition when the engine is stopped.

10. An ignition system for an internal combustion engine connected in driving relationship with at least one device having a member movable between a safe position for engine starting and an unsafe position for engine starting comprising:

a spark plug for the internal combustion engine;

an ignition transformer including a low tension primary and a high tension secondary winding connected with the spark plug for producing a sparking potential to fire the plug;

a source of low tension current pulses supplied in timed relationship with the engine cycle; and

an interlock connected between the source and the primary winding of the ignition transformer for controlling the transmission of current pulses from the source to the primary winding, the interlock including;

a first circuit path between the source and the primary winding having a first switch operably connected with the movable member and placing the first circuit in a pulse-transmitting condition when the movable member is in the safe position and a non-transmitting condition when the member is in the unsafe position;

a second circuit path parallel with the first path between the source and the primary winding and having a second switch with a control element operable to change the second switch and second circuit path between a non-transmitting condition and a transmitting condition for the pulses independently of the movable member and the first switch; and

actuating means connected with the first and second circuit paths and with the control element of the second switch and responsive to current pulses transmitted by the first and second circuit paths to the primary winding for placing the second switch in the transmitting condition to transmit further pulses to the primary winding and including release means permitting the second switch to return to the non-transmitting condition in the absence of further current pulses, said release means having a time constant preventing the second switch from returning to the non-transmitting condition in less than 0.1 second after current pulses are terminated and ensuring the return to the non-transmitting condition in a period of time not greater than three seconds.