PROTECTIVE CONTROL CIRCUIT FOR VEHICLE ELECTRICAL SYSTEMS

• US 3,781,651 A
• Filed: 11/09/1972
• Issued: 12/25/1973
• Est. Priority Date: 11/09/1972
• Status: Expired due to Term

• Current Assignee: Rodney L. Heidel
• Original Assignee: Rodney L. Heidel
• Inventors: Heidel, Rodney L.
• Primary Examiner(s): Trammell, James D.
• Application Number:
  US05/305,198
• Time in Patent Office: 411 Days
• Field of Search: 307/1R 317/33R,DIG.6,154 322/8 320/61
• US Class Current: 322/8
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0034 using reverse polarity correcting or protecting circuits mechanical means of polarity protection H02J7/0045
• CPC Class Codes: H02J 7/14 for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle

Abstract

A protective control circuit is disclosed for vehicle electrical systems such as those used on trucks and military vehicles. Such electrical systems are provided with a reverse polarity relay for connecting the battery to the generator. When the accessory switch is closed to energize the reverse polarity relay a holding circuit is provided for the relay so that the battery remains connected with the generator even after the accessory switch is opened to shut down the engine. The continued connection of the battery with the generator serves to avoid transient overvoltages which would be damaging to electrical components connected in the system. When the engine and hence the generator stops spinning the battery is disconnected from the generator by disabling the holding circuit.

Claims

1. For use with a vehicle including a prime mover and having an electrical system of the type which includes a battery, a generator electrically connectable to said battery and driven by said prime mover, manually actuated switching means in circuit with said battery, electrically actuated switching means connected with said manually actuated switching means and adapted when actuated to a first condition to connect the battery to the generator, the improvement comprising a holding circuit for said electrically actuated switching means to hold it in said first condition, and condition responsive switching means connected with said holding circuit and being responsive to running of said prime mover for enabling said holding circuit and operative to disable the holding circuit when the prime mover stops whereby the battery remains connected to the generator after said manually actuated switching means are deactuated so long as the prime mover and generator are running.

2. The invention as defined in claim 1 wherein said electrical system includes at least one electrical load device, said manually actuated switching means includes first switching contacts for connecting said load device and the electrically actuated switching means to the battery and includes second switching contacts for starting the prime mover.

3. The invention as defined in claim 2 including a diode in series with said electrically actuated switching means to prevent actuation thereof when the battery is connected with the wrong polarity.

4. The invention as defined in claim 3 wherein said prime mover is an engine, a starter motor connected with the engine, said second switching contacts being adapted to energize said starter motor to crank said engine.

5. The invention as defined in claim 4 including a starter relay connected between said second switching contacts and said battery through said electrically actuated switching means.

6. The invention as defined in claim 5 wherein said engine is provided with an engine driven fuel pump, and wherein said condition responsive switching means is a fluid responsive pressure switch operatively connected with the fluid outlet of said pump.

7. The invention as defined in claim 6 wherein said electrically actuated switching means has an input connected between the first switching contacts and the battery and has an output connected between the battery and the generator, said electrically actuated switching means being actuated to the first condition when the first switching contacts are actuated.

8. The invention as defined in claim 7 wherein said electrically actuated switching means comprises a relay having an energizing winding constituting said input and havIng switching contacts constituting said output.

9. The invention as defined in claim 2 wherein said holding circuit comprises second electrically actuated switching means having an input connected in a circuit with the battery when the first mentioned electrically actuated switching means connects the battery to the generator and having an output connected across the input of the first mentioned electrically actuated switching means.

10. The invention as defined in claim 8 wherein said holding circuit comprises at least one switching transistor having an input and an output, bias means connected with said battery when the first mentioned electrically actuated switching means connects the battery to said generator, said input of the transistor being connected to said bias means, the output of said transistor being connected with said energizing winding of said relay, said pressure responsive switch being connected across said bias means through the winding of said starter relay and being open when said engine is running whereby said holding circuit is enabled said pressure responsive switch being closed when said engine is stopped thereby shunting said bias means and disabling said holding circuit to deactuate the reverse polarity relay and disconnect said battery from said generator.

11. The invention as defined in claim 8 wherein said engine is a diesel engine and wherein at least one electrical load device must be energized from said battery before said engine is started.

12. The invention as defined in claim 11 wherein said holding circuit comprises second electrically actuated switching means having an input connected in a circuit with the battery when the first mentioned electrically actuated switching means connects the battery to the generator and having an output connected across the input of the first mentioned electrically actuated switching means.

13. The invention as defined in claim 12 wherein said holding circuit comprises first and second transistors each having an input and an output and being connected in cascade, said bias means being connected to said generator and the input of the first transistor being connected to said bias means, the output of said second transistor being connected between said generator and said energizing winding of the reverse polarity relay whereby said reverse polarity relay is held actuated, and a diode connected in the output of said second transistor between the transistor and said energizing coil to block reverse polarity voltage from said second transistor.