Apparatus for protecting eletronic devices in a vehicle's electronic system and for preventing discharge of the vehicle's battery

• US 5,764,469 A
• Filed: 03/10/1997
• Issued: 06/09/1998
• Est. Priority Date: 07/11/1995
• Status: Expired due to Fees

• Current Assignee: TAS Distributing Company Incorporated
• Original Assignee: TAS Distributing Company Incorporated
• Inventors: Sutton, Loran, Slepian, Harvey
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): JACKSON, STEPHEN W
• Application Number:
  US08/814,619
• Time in Patent Office: 456 Days
• Field of Search: 361/90, 361/115, 361/92, 361/72, 361/94, 320/32
• US Class Current: 361/92
• CPC Class Codes: H02H 3/207 also responsive to under-voltage window comparators for indication G01R19/165
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

An apparatus to provide protection for electronic devices which receive power for their operation at least in part from a vehicle'"'"'s electrical system and battery. The electronic device protecting apparatus has an electrical system voltage sensor, an engine start sensor, and an electronic device decoupler interconnected such that the electronic devices are decoupled from the electrical system and battery when the battery voltage drops below a predetermined level and when the engine is being started. The preferred apparatus allows the operator to select between a warning that system voltage is low and an automatic restart of the vehicle'"'"'s engine and charging system. The apparatus further includes a bypass function to accommodate electronic devices which draw temporarily high current.

Claims

1. A circuit for protecting an electronic device operatively installed in a vehicle from voltage spikes and surges produced when the vehicle is started, the vehicle having an electrical system which connects the electronic device to a battery included in the electrical system, and for preventing the electronic device from discharging the battery below an acceptable level, the circuit comprising:

first determining means for determining when the battery has been discharged below a first voltage level;

first disconnecting means, connected to said first determining means, for disconnecting the electronic device from the electrical system when the battery has been discharged below said first voltage level, the remainder of the electrical system remaining connected to the battery;

sensing means for sensing when the vehicle is being started;

second disconnecting means, connected to said sensing means, for disconnecting, the electronic device from the electrical system when the vehicle is being started;

second determining means for determining when the battery is being charged above a second voltage level;

first reconnecting means for reconnecting the electronic device to the electrical system, after the electronic device has been previously disconnected from the electrical system by said first disconnecting means, when said second determining means indicates the battery is being charged above said second voltage level;

second reconnecting means for reconnecting the electronic device to the electrical system, after the electronic device has been previously disconnected from the electrical system by said second disconnecting means, when said sensing means indicates the vehicle is not being started;

third determining means for determining when the battery has been discharged below a third voltage level, said third voltage level higher than said first voltage level; and

automatic restart means, connected to said third determining means, for automatically starting the vehicle to recharge the vehicle'"'"'s battery when the battery has been discharged below said third voltage level.

2. The circuit according to claim 1, further comprising switch means, connected to said third determining means, for permitting said operator to select from among an audible warning means, a visible warning means, and said automatic restart means.

3. The circuit according to claim 1, wherein said first disconnecting means comprises a power transistor connected intermediate the electrical system and the electronic device.

4. The circuit according to claim 1, wherein said second disconnecting means comprises a relay connected intermediate the electrical system and the electronic device.

5. The circuit according to claim 1, further comprising switch means, selectively coupling to said third determining means with an audible warning means, a visual warning means, and said automatic restart means to be activated when the battery has been discharged below said third voltage level.

6. The circuit according to claim 1, further comprising a voltage reference source connected to the electrical system for producing said first voltage level and said second voltage level and said third voltage level.

7. The circuit according to claim 6, wherein said first determining means comprises a comparator connected to said voltage reference source, the electrical system, and said first disconnecting means.

8. The circuit according to claim 6, wherein said second determining means comprises a comparator connected to said voltage reference source, the electrical system, and said first reconnecting means.

9. The circuit according to claim 6, wherein said third determining means comprises a comparator connected to said voltage reference source, the electrical system, and said automatic restart means.

10. Apparatus for protecting an electronic device installed in a vehicle, the vehicle having an engine and an electrical system for supplying voltage to operate the electronic device, the electrical system including a battery having a first voltage, an alternator producing a second voltage when being driven by the vehicle'"'"'s engine, and a charging circuit for charging the battery with the second voltage produced by the alternator, the electrical system having a first state in which the engine is not running, a second state in which the engine is being started, and a third state in which the engine is running, and an operator of the vehicle selecting from among the first, second, and third states, the apparatus comprising:

a power transistor for electrically connecting and disconnecting the electronic device from the electrical system;

a voltage reference source, connected to the electrical system, for producing a first and second predetermined reference voltage, said first reference voltage being less than said second reference voltage;

a first comparator, connected to the electrical system and said voltage reference source, for comparing the first voltage to said first reference voltage and activating said power transistor to disconnect the electronic device from the electrical system when the first voltage is less than said first reference voltage;

an automatic restart signal for automatically starting the vehicle'"'"'s engine to recharge the battery with the second voltage produced by the alternator when the first voltage is less than said second predetermined reference voltage;

a second comparator, connected to the electrical system and said voltage reference source, for activating said automatic restart signal when the first voltage is less than said second predetermined reference voltage;

a third comparator, connected to the electrical system and said voltage reference source, for activating said power transistor to connect the electronic device to the electrical system when the alternator is producing the second voltage, the electrical system being in the third state;

a start signal activated when the electrical system is in the second state; and

a relay, connected to said start signal, for disconnecting the electronic device from the electrical system when the electrical system is in the second state.

11. The apparatus according to claim 10, further comprising a secondary battery for supplying power to the electronic device when said relay disconnects the electronic device from the electrical system.

12. The apparatus according to claim 10, further comprising a first time delay circuit connected to said relay for continuing to disconnect the electronic device from the electrical system for a predetermined period of time after the electrical system is no longer in the second state.

13. The apparatus according to claim 10, further comprising an integrated circuit which includes said first, said second, and said third comparators.

14. The apparatus according to claim 10, further comprising, a switch circuit selectively coupling said second comparator to an audible warning signal, a visible warning signal, and said automatic restart signal.

15. A circuit for protecting an electronic device operatively installed in a vehicle from voltage spikes and surges produced when the vehicle is started, the vehicle having an electrical system which connects the electronic device to a battery included in the electrical system, and for preventing the electronic device from discharging the battery below an acceptable level, the circuit comprising:

first determining means for determining when the battery has been discharged below a first voltage level;

first disconnecting means, connected to said first determining means, for disconnecting the electronic device from the electrical system when the battery has been discharged below said first voltage level, the remainder of the electrical system remaining connected to the battery;

sensing means for sensing when the vehicle is being started;

second disconnecting means, connected to said sensing means, for disconnecting the electronic device from the electrical system when the vehicle is being started;

second determining means for determining when the battery is being charged above a second voltage level;

first reconnecting means for reconnecting the electronic device to the electrical system, after the electronic device has been previously disconnected from the electrical system by said first disconnecting means, when said second determining means indicates the battery is being charged above said second voltage level;

second reconnecting means for reconnecting the electronic device to the electrical system, after the electronic device has been previously disconnected from the electrical system by said second disconnecting means, when said sensing means indicates the vehicle is not being started; and

bypass means which overrides said first determining means and said second determining means, and prevents the apparatus from connecting or disconnecting electronic devices, when a bypass input signal is received.

16. The circuit according to claim 15, wherein said first disconnecting means comprises a power transistor connected intermediate the electrical system and the electronic device.

17. The circuit according to claim 15, wherein said second disconnecting means comprises a relay connected intermediate the electrical system and the electronic device.

18. The circuit according to claim 15, further comprising bypass delay means connected to said bypass means for continuing to bypass said determining means for a predetermined period of time after the bypass input signal is deactivated.

19. The circuit according to claim 15 further comprising:

third determining means for determining when the battery has been discharged below a third voltage level, said third voltage level higher than said first voltage level; and

warning means, connected to said third determining means, for warning an operator of the vehicle that the battery has been discharged below said third voltage level and that remedial action is necessary to prevent disconnection of the electronic device from the electrical system.

20. The circuit according to claim 19, wherein said bypass means also overrides said third determining means.

21. The circuit according to claim 19, wherein said warning means includes switch means for permitting said operator to select from among an audible warning means and a visible warning means to be operated by said warning means.

22. The circuit according to claim 21, wherein said switch means further allows the operator to select automatic restart means to be activated when the battery has been discharged below said third voltage level.

23. The circuit according to claim 15, further comprising a voltage reference source connected to the electrical system for providing said first voltage level and said second voltage level.

24. The circuit according to claim 23, wherein said first determining means comprises a comparator connected to said voltage reference source, the electrical system, and said first disconnecting means.

25. The circuit according to claim 23, further comprising:

third determining means for determining when the battery has been discharged below a third voltage level, said third voltage level higher than said first voltage level.

26. The circuit according to claim 25, further comprising:

warning means, connected to said third determining means, for warning an operator of the vehicle that the battery has been discharged below said third voltage level and that remedial action is necessary to prevent disconnection of the electrical device from the electrical system.

27. The circuit according to claim 25, wherein said bypass means also overrides said third determining means.

28. Apparatus for protecting an electronic device installed in a vehicle, the vehicle having an engine and an electrical system for supplying voltage to operate the electronic device, the electrical system including a battery having a first voltage, an alternator producing a second voltage when being driven by the vehicle'"'"'s engine, and a charging circuit for charging the battery with the second voltage produced by the alternator, the electrical system having a first state in which the engine is not running, a second state in which the engine is being started, and a third state in which the engine is running, and an operator of the vehicle selecting from among the first, second, and third states, the apparatus comprising:

a power transistor for electrically connecting and disconnecting the electronic device from the electrical system;

a voltage reference source, connected to the electrical system, for producing a first and a second predetermined reference voltage, said first reference voltage being less than said second reference voltage;

a first comparator, connected to the electrical system and said voltage reference source, for comparing the first voltage to said first reference voltage and activating said power transistor to disconnect the electronic device from the electrical system when the first voltage is less than said first reference voltage;

a warning circuit for warning the operator that remedial action is necessary to prevent disconnection of the electronic device from the electrical system, said warning circuit issuing a warning when the first voltage is less than said second predetermined reference voltage;

a second comparator, connected to the electrical system and said voltage reference source, for activating said warning circuit when the first voltage is less than said second predetermined reference voltage;

a third comparator, connected to the electrical system and said voltage reference source, for activating said power transistor to connect the electronic device to the electrical system when the alternator is producing the second voltage, the electrical system being in the third state;

a sensing circuit for sensing when the electrical system is in the second state;

a relay, connected to said sensing circuit, for disconnecting the battery from the electronic device from the electrical system when the electrical system is in the second state; and

a bypass circuit, connected to and overriding said first, said second, and said third comparators, in response to a bypass input signal indicating an electronic device requiring a temporarily high initial current has been started.

29. The apparatus according to claim 28, further comprising a secondary battery for supplying power to the electronic device when said relay disconnects the electronic device from the electrical system.

30. The apparatus according to claim 28, further comprising a first time delay circuit connected to said relay for continuing to disconnect the electronic device from the electrical system for a predetermined period of time after the electrical system is no longer in the second state.

31. The apparatus according to claim 28, further comprising a bypass time delay circuit connected to said bypass circuit for continuing to bypass said first, said second, and said third comparators for a predetermined period of time after the bypass input signal is deactivated.

32. The apparatus according to claim 28, further comprising an integrated circuit which includes said first, said second, and said third comparators.

33. The apparatus according to claim 28, wherein said warning circuit comprises a switch for permitting the operator to select from among an audible warning signal and a visible warning signal.

34. The apparatus according to claim 33, wherein said switch further allows the operator to select an automatic restart signal to be activated when the battery has been discharged below said third voltage level.