Dual voltage motor vehicle electrical system

• US 4,492,912 A
• Filed: 01/12/1983
• Issued: 01/08/1985
• Est. Priority Date: 01/12/1983
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Nowakowski, Robert J.
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US06/457,495
• Time in Patent Office: 727 Days
• Field of Search: 320/2-4, 320/6, 320/7, 320/15-17, 320/21, 320/22, 320/51, 320/64, 320/37, 322/89, 322/90, 322/26, 307/16
• US Class Current: 320/123
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A dual voltage motor vehicle electrical system comprising series connected cranking and accessory batteries that are used to energize an electric vehicle engine cranking motor. The accessory battery is charged by a vehicle engine driven generator and the cranking battery is charged by a battery charging circuit having an input connected to the accessory battery and an output connected to the cranking battery. The battery charging circuit is maintained in operation for a period of time after shut down of the engine to charge the cranking battery from the accessory battery. The battery charging circuit includes an inductance coil for transferring energy between the accessory and cranking batteries which may take the form of an actuating coil of a magnetic switch the contacts of which disconnect the accessory battery from an electrical load when the actuating coil is deenergized.

Claims

1. A dual voltage motor vehicle electrical system comprising in combination, first and second series connected batteries for supplying an electrical engine cranking motor with a voltage corresponding to the sum of the voltages of the batteries, at least one of said batteries being connected to supply at least one other electrical load with a lower voltage corresponding to its terminal voltage, a voltage regulated direct voltage generating means driven by the engine of the vehicle, conductor means connecting the output terminals of said generating means to the terminals of said first battery whereby said first battery is charged by said generating means, a control means having an input connected to said conductor means and an output connected to the terminals of said second battery for charging said second battery from the voltage applied to said conductor means, said control means including means for varying the charging current supplied to said second battery as a function of the terminal voltage of said second battery, and means for maintaining said control means in operation for a predetermined time period following shut down of said engine to charge said second battery from said first battery for said time period.

2. A dual voltage motor vehicle electrical system comprising, first and second series connected batteries, an electrical vehicle engine cranking motor adapted to be connected across said series connected batteries so as to be energized by the sum of the terminal voltages of said batteries, a battery charging generator driven by the engine of the vehicle, conductor means connecting said generator across said first battery to charge said first battery, an energy storage device, circuit means including a diode connecting said energy storage device across said second battery, a circuit including a switching means connecting said energy storage device across said conductor means and first battery, control means for causing said switching means to switch on and off at predetermined frequency whereby said energy storage device is charged by the voltage across said conductor means when said switching means is conductive and supplies energy to said second battery through said diode when nonconductive, and means for maintaining said control means in operation for a time period after shut down of said engine to thereby charge said second battery from said first battery for said time period.

3. A dual voltage motor vehicle electrical system comprising, first and second series connected batteries, an electrical vehicle engine cranking motor adapted to be connected across said series connected batteries so as to be energized by the sum of the terminal voltages of said batteries, a battery charging generator driven by the engine of the vehicle, conductor means connecting said generator across said first battery to charge said first battery, an inductor, circuit means including a diode connecting said inductor across said second battery, a circuit including a switching means connecting said inductor across said conductor means and first battery, an oscillator coupled to said switching means to cause it to switch on and off at the output frequency of the oscillator whereby said inductor is energized by the voltage across said conductor means when said switching means is conductive and supplies energy to said second battery through said diode when nonconductive, means for varying the output frequency of said oscillator as a function of the terminal voltage of said second battery to control the average charging current to said second battery, and means for maintaining said oscillator in operation for a time period after shut down of said engine to thereby charge said second battery from said first battery for said time period.

4. A motor vehicle electrical system comprising, first and second series connected batteries, an electric cranking motor adapted to be connected across said batteries to be energized thereby, a generator driven by the vehicle engine connected to charge said first battery, a magnetic switch comprising an actuating coil and switch contacts which are closed when said actuating coil is energized and open when said coil is not energized, switching means for connecting and disconnecting said actuating coil to and from said first battery at a switching rate that is sufficient to maintain said magnetic switch contacts closed, means for applying energy stored in said actuating coil to said second battery when said switching means disconnents said actuating coil and first battery, an electrical load circuit for feeding an electrical load, means connecting said magnetic switch contacts between said first battery and said electrical load circuit, and means for maintaining said switching means in operation for a time period after engine shut down to thereby charge said second battery from said first battery and maintain said first battery connected to said electrical load circuit for said time period, the termination of operation of said switching means being operative to terminate charging of said second battery and operative to cause said magnetic switch contacts to open to disconnect said first battery from said load circuit.

5. An electrical system for charging a first storage battery from a second storage battery and for connecting and disconnecting an electrical load circuit to and from said second battery comprising, first and second storage batteries, a magnetic switch having an actuating coil and switch contacts which are closed when the actuating coil is energized, the switch contacts opening when the actuating coil is not energized, means connecting the switch contacts of said magnetic switch between said second battery and said load circuit whereby said load circuit and second battery are connected when said switch contacts are closed and are disconnected when said switch contacts are open, a switching means for connecting and disconnecting said actuating coil to and from said second battery at a switching rate that is sufficient to maintain said magnetic switch contacts closed, means for supplying energy stored in said actuating coil to said first battery when said switching means disconnects said actuating coil and second battery, and means for deenergizing said actuating coil to thereby cause termination of the charging of said first battery from said second battery and cause said magnetic switch contacts to open to disconnect said second battery and load circuit.