Engine speed control circuit for emergency vehicle

• US 4,527,112 A
• Filed: 12/14/1983
• Issued: 07/02/1985
• Est. Priority Date: 12/14/1983
• Status: Expired due to Fees

• Current Assignee: Charles A. Herman
• Original Assignee: Charles A. Herman
• Inventors: Herman, Charles A.
• Primary Examiner(s): HicKey, R. J.
• Application Number:
  US06/561,536
• Time in Patent Office: 566 Days
• Field of Search: 320/12, 320/62, 320/61, 290/40 R, 290/40 B, 290/40 F, 290/50, 307/10, 322/38
• US Class Current: 322/38
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/14 for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A control circuit for a vehicle electrical system which is operative when the vehicle engine is running but the vehicle is not in motion to sense vehicle storage battery voltage and, when that voltage is below a predetermined threshold, to enable an electrically controllable device to open somewhat the engine throttle raising engine speed and increasing the output of an engine driven electrical source. The control circuit finds particular utility in emergency vehicles such as ambulances and the like where that vehicle may remain at an emergency site for an extended period of time with the engine idling and with numerous electrical demands on the vehicle electrical system to increase the engine speed when those electrical demands have sufficiently exceeded the output of an engine driven alternator with the engine running at idle.

Claims

1. A control circuit for a vehicle electrical system of the type where the vehicle engine functions as a prime mover of a voltage regulated electrical source with that source in turn supplying current to meet the electrical requirements of the vehicle including vehicle storage battery charging current comprising;

means for selectively maintaining a vehicle engine throttle at an engine speed setting above normal engine idle;

means for monitoring vehicle storage battery voltage;

means responsive to an indication by the monitoring means that battery voltage is less than a predetermined threshold for enabling the means for selectively maintaining thereby driving the electrical source at a higher speed and correspondingly higher output than the speed and output corresponding to engine idle, including latching circuitry whereby once enabled the engine speed remains above normal idle even though battery voltage rises above the predetermined threshold; and

means responsive to vehicle driver intervention for disabling the latching circuitry to allow engine speed to return to normal idle comprising a switch actuated by movement of a vehicle transmission control lever for disabling the latching circuitry when the vehicle transmission is in other than a neutral state.

2. The control circuit of claim 1 wherein the means responsive to driver intervention additionally comprises a normally open manually actuable switch which may be momentarily closed by the driver to disable the latching circuitry.

3. The control circuit of claim 1 further comprising a normally open manually actuable switch which may be momentarily closed by a vehicle operator to cause the responsive means to enable the means for selectively maintaining regardless of any indication by the monitoring means.

4. The control circuit of claim 1 wherein the means for selectively maintaining comprises a vacuum actuable piston which when actuated moves into a position holding the engine throttle part way open.

5. The control circuit of claim 4 further comprising an electrically actuable vacuum control valve which when enabled connects an engine vacuum line to the vacuum actuable piston.

6. The control circuit of claim 5 wherein both the vacuum actuable piston and vacuum control valve are dual purpose devices being further employed for conventional engine emission reduction by holding the throttle slightly open during vehicle deceleration at engine speeds above a specified value.

7. The control circuit of claim 1 wherein the means for monitoring storage battery voltage includes a voltage sensing circuit including a zener diode and a control circuit including a transistor.

8. The control circuit of claim 7 wherein the transistor is in a conductive state and the zener diode is reverse biased and conducting so long as the battery voltage exceeds the predetermined threshold.

9. In an engine powered vehicle of the type having a storage battery, an engine driven voltage regulated electrical source for charging the storage battery and supplying the other electrical needs of the vehicle system and an engine emission reduction system including an electrically controllable mechanical device for holding an engine throttle control somewhat more open than its normal idle position during vehicle deceleration at engine speeds above a specified speed, the improvement comprising a control circuit operative when the vehicle engine is running but the vehicle is not in motion to sense battery voltage and when that voltage is below a predetermined threshold to enable the electrically controllable device to open somewhat the engine throttle raising engine speed and increasing the output of the engine driven electrical source, the control circuit including means for monitoring vehicle storage battery voltage, means responsive to an indication by the monitoring means that battery voltage is less than the predetermined threshold for providing an output to enable the electrically controllable mechanical device including latching circuitry whereby once enabled the engine speed remains above normal idle even though battery voltage rises above the predetermined threshold, and first, second and third means responsive to vehicle driver intervention for disabling the latching circuitry to allow engine speed to return to normal idle, the first means comprising a switch actuated by movement of a vehicle transmission control lever for disabling the latching circuitry when the vehicle transmission is in other than a neutral state, the second means comprising the vehicle brake light actuating switch connected to disable the latching circuitry when the brake lights are energized, the third means comprising a normally open manually actuable switch which may be momentarily closed by the driver to disable the latching circuitry, a normally open manually actuable switch which may be momentarily closed by a vehicle operator to cause the responsive means to provide an output to enable the electrically controllable mechanical device regardless of any indication by the monitoring means, the means for monitoring vehicle storage battery voltage including a voltage sensing circuit having a zener diode and a control circuit having a transistor with the transistor being in a conductive state and the zener diode being reversed biased and conducting so long as the battery voltage exceeds the predetermined threshold, and responsive means comprising first and second transistors coupled together so that the conductive state of the second transistor is directly controlled by the conductive state of the first transistor with the means for monitoring maintaining the base and emitter of the first transistor at substantially the same potential thereby denying that transistor any base drive current and maintaining that transistor in a nonconconductive state so long as battery voltage is above the predetermined threshold, the third means for disabling comprising an "off" button which upon actuation connects the base and emitter of the first transistor rendering that transistor nonconductive and depriving the second transistor of any base drive current to also render the second transistor nonconductive.

10. A control circuit for a vehicle electrical system of the type where the vehicle engine functions as a prime mover of a voltage regulated electrical source with that source in turn supplying current to meet the electrical requirements of the vehicle including vehicle storage battery charging current comprising;

means for selectively maintaining a vehicle engine throttle at an engine speed setting above normal engine idle;

means for monitoring vehicle storage battery voltage;

means responsive to an indication by the monitoring means that battery voltage is less than a predetermined threshold for enabling the means for selectively maintaining thereby driving the electrical source at a higher speed and correspondingly higher output than the speed and output corresponding to engine idle, including latching circuitry whereby once enabled the engine speed remains above normal idle even through battery voltage rises above the predetermined threshold; and

means responsive to vehicle driver intervention for disabling the latching circuitry to allow engine speed to return to normal idle comprising a vehicle brake light actuating switch connected to disable the latching circuitry when the brake lights are energized.

11. The control circuit of claim 10 wherein the means responsive to driver intervention additionally comprises a normally open manually actuable switch which may be momentarily closed by the driver to disable the latching circuitry.

12. The control circuit of claim 10 further comprising a normally open manually actuable switch which may be momentarily closed by a vehicle operator to cause the responsive means to enable the means for selectively maintaining regardless of any indication by the monitoring means.

13. The control circuit of claim 10 wherein the means for selectively maintaining comprises a vacuum actuable piston which when actuated moves into a position holding the engine throttle part way open.

14. The control circuit of claim 13 further comprising an electrically actuable vacuum control valve which when enabled connects an engine vacuum line to the vacuum actuable piston.

15. The control circuit of claim 14 wherein both the vacuum actuable piston and vacuum control valve are dual purpose devices being further employed for conventional engine emission reduction by holding the throttle slightly open during vehicle deceleration at engine speeds above a specified value.

16. The control circuit of claim 10 wherein the means for monitoring storage battery voltage includes a voltage sensing circuit including a zener diode and a control circuit including a transistor.

17. The control circuit of claim 16 wherein the transistor is in a conductive state and the zener diode is reverse biased and conducting so long as the battery voltage exceeds the predetermined threshold.

18. A control circuit for a vehicle electrical system of the type where the vehicle engine functions as a prime mover of a voltage regulated electrical source with that source in turn supplying current to meet the electrical requirements of the vehicle including vehicle storage battery charging current comprising;

means for selectively maintaining a vehicle engine throttle at an engine speed setting above normal engine idle;

means for monitoring vehicle storage battery voltage;

means responsive to an indication by the monitoring means that battery voltage is less than a predetermined threshold for enabling the means for selectively maintaining thereby driving the electrical source at a higher speed and correspondingly higher output than the speed and output corresponding to engine idle, including first and second transistors coupled together so that the conductive state of the second is directly controlled by the conductive state of the first, the means for monitoring maintaining the base and emitter of the first transistor at substantially the same potential thereby denying the first transistor any base drive current and maintaining that transistor in a nonconductive state so long as battery voltage is above the predetermined threshold, the first and second transistors each being provided with a bias resistor coupled between base and emitter for ensuring that the respective transistor remains nonconducting until switched into a conducting state;

a light emitting diode in circuit between the first and second transistors illuminated by current flow therebetween indicating that the engine is being held at a speed higher than normal idle; and

an operator actuable "off" button which upon actuation connects the base and emitter of the first transistor rendering that transistor nonconductive and depriving the second transistor of any base drive current to also render the second transistor nonconductive.

19. A control circuit for a vehicle electrical system of the type where the vehicle engine functions as a prime mover of a voltage regulated electrical source with that source in turn supplying current to meet the electrical requirements of the vehicle including vehicle storage battery charging current comprising;

means for selectively maintaining a vehicle engine throttle at an engine speed setting above normal engine idle;

solid state control circuitry for enabling the means for selectively maintaining thereby driving the electrical source at a higher speed and correspondingly higher output than the speed and output corresponding to engine idle; and

means responsive to vehicle driver intervention for disabling the solid state control circuitry returning engine speed to normal idle comprising a vehicle brake light actuating switch connected to disable the solid state control circuitry when the brake lights are energized, and a switch actuated by movement of a vehicle transmission control lever for disabling the solid state control circuitry when the vehicle transmission is in other than a neutral state.

20. The control circuit of claim 19 wherein the means for selectively maintaining comprises a vacuum actuable piston which when actuated moves into a position holding the engine throttle part way open.

21. The control circuit of claim 20 further comprising an electrically actuable vacuum control valve which when enabled connects an engine vacuum line to the vacuum actuable piston.

22. The control circuit of claim 21 wherein both the vacuum actuable piston and vacuum control valve are dual purpose devices being further employed for conventional engine emission reduction by holding the throttle slightly open during vehicle deceleration at engine speeds above a specified value.