Fault indicator for motor vehicle battery charging systems

• US 4,019,120 A
• Filed: 04/02/1976
• Issued: 04/19/1977
• Est. Priority Date: 04/02/1976
• 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: Fattic, Gerald T.
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/672,872
• Time in Patent Office: 382 Days
• Field of Search: 322/28, 322/99, 317/13 R, 324/73, 324/158 MG, 340/248, 340/248 Y, 340/249, 320/48, 320/39
• US Class Current: 322/28
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/16 Regulation of the charging current or voltage by variation of field

Abstract

A fault indicator for a motor vehicle battery charging system of the type in which a diode-rectified alternating current generator supplies charging current to the vehicle battery and supplies other loads on the vehicle. The fault indicator is capable of detecting certain faults in the diode-rectified alternator and is capable of detecting certain faults in the generator voltage regulating system. The fault indicator system utilizes current difference operational amplifiers, one of which is connected to detect sharp negative voltage transitions caused by certain faults in the system. The fault indicator also has Zener diodes connected to provide an indication of faults that cause abnormally low or high voltage outputs of the diode-rectified alternator such as an open or shorted voltage regulator. The signal indicator utilized is a light emitting diode and the fault indicator circuit is arranged so as to cause continuous illumination of the light emitting diode under certain fault conditions and a blinking of the light emitting diode during other fault conditions.

Claims

1. A malfunction indicator for a motor vehicle battery charging system comprising, an alternating current generator having a polyphase output winding and a field winding, a first full-wave bridge rectifier connected to said output winding, a battery connected across the direct current output terminals of said first bridge rectifier to be charged thereby, second rectifier means connected with said output winding, said second rectifier means and certain of the rectifiers of said bridge rectifier providing a field energizing rectifier circuit having direct current field energizing terminals, voltage regulating means including a field current control means, means connecting said field winding and said field current control means across said field energizing terminals of said field energizing rectifier circuit to provide regulated field excitation for said generator, an amplifier having first and second inputs operative to provide an output signal when the input currents to said amplifier inputs differ by a predetermined amount, means connecting the inputs of said amplifier to said field energizing terminals including a diode connected across said amplifier input terminals and a capacitor connected between one amplifier input terminal and one field energizing terminal, said diode and capacitor operative to cause a differential input current to be supplied to said amplifier inputs of sufficient magnitude as to cause said amplifier to develop a first output fault signal in response to the occurrence of sudden voltage transitions across said field energizing terminals indicative of certain faults in said system, means connected to said battery and to one of said field energizing terminals for providing a second fault signal when a predetermined voltage difference exists therebetween indicative of faulty field excitation, and fault signal indicating means operative to respond to said first and second fault signals.

2. A malfunction indicator for a motor vehicle battery charging system comprising, an alternating current generator having an output winding and a field winding, a full-wave bridge rectifier connected to said output winding having direct voltage output terminals, a battery, first and second conductor means respectively connecting said direct voltage output terminals of said bridge rectifier to said battery, field energizing rectifier means connected to said output winding having direct voltage output terminals, a field excitation circuit connected across said direct voltage output terminals of said field energizing rectifier means comprising said field winding and the field current control means of a voltage regulating means, a first junction connected to one of said first and second conductor means, said first junction having a voltage of a regulated value determined by said voltage regulating means which is in excess of battery voltage during normal operation of said field excitation circuit, the voltage of said first junction being substantially equal to battery terminal voltage during an open condition of said field excitation circuit and higher than said regulated value during a shorted condition of said field excitation circuit, a second junction, said second junction located in a circuit connected across the direct voltage output terminals of said field energizing rectifier means, said last-named circuit including a first Zener diode connected between said second junction and one of the direct voltage output terminals of said field energizing rectifier means, the voltage of said second junction substantially equalling the break down voltage of said first Zener diode when the output voltage of said field energizing rectifier means is substantially equal to or in excess of said regulated value, a second Zener diode connected between said first and second junctions, the break down voltage of said second Zener diode being of such a value that the voltage of said second junction is less than the break down voltage of said first Zener diode when the output voltage of said generator drops to some value indicative of an open condition in said field excitation circuit, and means connected to said first and second junctions for developing a fault signal when the voltage of said first junction exceeds the voltage of said second junction by a predetermined amount.

3. A malfunction indicator for a motor vehicle battery charging system of a type that has an alternating current generator connected to first rectifier means for supplying charging current to the battery and having second rectifier means connected to the generator to provide generator field excitation comprising, an input circuit adapted to be connected across the output terminals of said second rectifier means, said input circuit having positive and negative terminal ends adapted to be connected with like polarity terminals of said second rectifier means, said input circuit comprising in a series connection a diode and a capacitor having a common junction, said diode having its anode connected to said positive end of said input circuit and its cathode connected to said common junction, said capacitor connected between said common junction and said negative end of said input circuit, a first current difference amplifier having first and second input terminals, said current difference amplifier developing an output when the current supplied to its first input terminal exceeds the current supplied to its second input terminal, means connecting said input terminals of said first amplifier respectively to opposite sides of said diode with said first amplifier input terminal connected to said common junction, the voltage attained by said capacitor operative to cause a differential input current to be supplied to said first amplifier of sufficient magnitude as to cause said first amplifier to develop an output when a negative voltage transition indicative of a fault in said battery charging system is applied to said input circuit, a filter circuit connected to the output of said first amplifier for filtering the pulsating output of said first amplifier, a second current difference amplifier having an input connected to receive the filtered output of said first amplifier, and fault signal indicating means responsive to the output voltage of said second amplifier for indicating the occurrence of a fault condition.

4. A malfunction indicator for a motor vehicle battery charging system comprising, an alternating current generator having a polyphase output winding and a field winding, a first bridge rectifier connected to said output winding having positive and negative direct voltage output terminals, a battery, conductor means connecting said direct voltage output terminals of said bridge rectifier to said battery, second field energizing rectifier means connected with said output winding having direct voltage output terminals, voltage regulating means including a field current control means, means connecting said field winding and said field current control means across said output terminals of said second rectifier means, a fault detecting circuit connected across the output terminals of said second rectifier means, said fault detecting circuit including means for developing a fault signal in response to the occurrence of sharp negative voltage transitions developed across said output terminals of said second rectifier means as a result of the occurrence of certain faults in said system, a first junction, means connecting said first junction to the conductor means connecting the positive direct voltage output terminal of said bridge rectifier to the positive terminal of said battery, the voltage of said first junction substantially equalling the voltage of the positive direct voltage output terminal of said bridge rectifier when the output voltage of said bridge rectifier exceeds battery voltage and substantially equalling the voltage of the positive terminal of said battery when the output voltage of said bridge rectifier is less than battery voltage, a second junction located on said fault detecting circuit, means coupled to said first and second junctions for developing a differential voltage of predetermined magnitude when the output voltage of said generator is abnormally higher or lower than a desired regulated value to be maintained by said voltage regulating means, means responsive to said differential voltage for developing a second fault signal, a signal light, means responsive to the occurrence of one of said fault signals for causing said signal light to be continuously energized, and means responsive to the other of said fault signals for causing said signal light to blink on and off.

5. A malfunction indicator for a motor vehicle battery charging system comprising, an alternating current generator having an output winding and a field winding, power bridge rectifier means having direct voltage output terminals connected to said output winding, a battery, power supply conductor means respectively connecting the direct voltage output terminal of said bridge rectifier to said battery for supplying charging current thereto, second rectifier means connected to said output winding having direct voltage output terminals, voltage regulating means including a field current control means, means connecting said field winding and said field current control means across the direct voltage output terminals of said second rectifier means, the output voltage developed across said second rectifier means exhibiting sharp negative voltage transitions during a fault condition of said system, fault detecting means connected across the output terminals of said second rectifier means, said fault detecting means including a first current difference amplifier operative to develop an output when a sharp negative voltage transition indicative of a fault condition occurs, a first junction, means connecting said first junction to one of the power conductors connecting the bridge rectifier to one terminal of said battery, the voltage of said first junction having a potential which is a function of the output voltage of said bridge rectifier when the output voltage of said bridge rectifier is in excess of battery voltage and having a voltage substantially equal to battery voltage when the output voltage of said bridge rectifier is less than battery voltage, a second junction connected to said fault detecting means whereby it has a voltage related to the output voltage of said second rectifier means, means including a second current difference amplifier connected to said first and second junctions and operative to cause said second amplifier to have an output when the output voltage of said generator is above or below a desired regulated value, an oscillator connected to said second amplifier, a light emitting diode, control means connected with said light emitting diode for controlling the energization thereof, and means respectively connecting the outputs of said first and second current difference amplifiers to said control means whereby said light emitting diode is continuously energized when said first amplifier develops an output and is caused to blink on and off at the output frequency of said oscillator when said second amplifier has an output.