Alternator testing apparatus

• US 4,459,548 A
• Filed: 11/12/1981
• Issued: 07/10/1984
• Est. Priority Date: 11/12/1981
• Status: Expired due to Term

• Current Assignee: Snap-On Incorporated
• Original Assignee: Snap-On Tools Company LLC (Snap-On Incorporated)
• Inventors: Servais, Stephen B., Lentz, Richard P.
• Primary Examiner(s): Levy, Stewart J.
• Application Number:
  US06/320,329
• Time in Patent Office: 971 Days
• Field of Search: 324/158 MG, 324/158 D, 324/140 D, 324/379, 324/384, 322/99, 340/645, 363/46
• US Class Current: 324/765.01
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/343 in operation

Abstract

An alternator produces current that has an average component and a ripple component. The alternator testing apparatus produces one voltage representative of the magnitude of the peak-to-peak amplitude of the ripple component and a second voltage representative of the sum of the average component and the peak-to-peak amplitude of the ripple component. A series of comparators each have their signal inputs coupled to receive the first voltage and their control inputs coupled to a divider network which is in turn coupled to receive the second voltage. Indicators are coupled to the comparators.

Claims

1. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising circuit means for generating at a first output thereof a first voltage representative of the amplitude of the ripple component and independent of the average component and for generating at a second output thereof a second voltage representative of the sum of the magnitude of the average component plus the amplitude of the ripple component, means for providing electrical signals representative of the ratio of the first voltage to the second voltage, and indicating means coupled to said providing means and being responsive to the electrical signals therefrom to provide information on the ratio.

2. The alternator testing apparatus of claim 1, wherein said indicating means is visual.

3. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising circuit means for generating at a first output thereof a first voltage representative of the amplitude of the ripple component and independent of the average component and for generating at a second output thereof a second voltage representative of the sum of the magnitude of the average component plus the amplitude of the ripple component, a plurality of comparators each having a signal input and a reference input and an output, said signal inputs being coupled to said first output, a divider network coupled to said second output for dividing the second voltage into a plurality of different reference voltages at a plurality of nodes in said network, said nodes being respectively coupled to said reference inputs, each comparator being activated when the first voltage exceeds the reference voltage associated with such comparator, and indicating means coupled to said comparator outputs and being energized in accordance with which comparator is activated.

4. The alternator testing apparatus of claim 3, wherein said plurality of comparators and said divider network are part of an integrated circuit.

5. The alternator testing apparatus of claim 3, and further comprising further circuit means coupled to the signal inputs of said comparators and to said divider network and being operative to allow the first and second voltages to be applied thereto only in the presence of an output signal of predetermined amplitude.

6. The alternator testing apparatus of claim 3, and further comprising a disabling circuit coupled to the signal inputs of said comparators and to said divider network and being responsive to the absence of an output signal of predetermined amplitude to disable said comparators.

7. The alternator testing apparatus of claim 3, and further comprising first gate means coupling the first output of said circuit means to the signal inputs of said comparators, second gate means coupling the second output of said circuit means to said divider network, said first and second gate means being operative to couple the first and second voltages respectively to said comparators and to said divider network in the presence of an output signal of predetermined amplitude.

8. The alternator testing apparatus of claim 3, wherein said divider network includes a plurality of resistors connected in series between the reference input of one of said comparators and a point of reference potential, the junctions of said resistors being respectively coupled to the reference inputs of the rest of said comparators, said second output being coupled to the reference input of said one comparator.

9. The alternator testing apparatus of claim 8 wherein each of said resistors has substantially the same value.

10. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising first filter means for receiving the output signal for passing the ripple component thereof, detector means coupled to said first filter means for generating a first voltage representative of the amplitude of the ripple component, second filter means coupled to receive the output signal for passing the average component, summing means coupled to said detector means and to said second filter means for generating a second voltage representative of the sum of the magnitude of the average component and the amplitude of the ripple component, a plurality of comparators each having a signal input and a reference input and an output, said signal inputs being coupled together and to said detector means, a divider network coupled to said summing means for dividing the second voltage into a plurality of different reference voltages at a plurality of nodes in said network, said nodes being respectively coupled to said reference inputs, each comparator being activated when the first voltage exceeds the reference voltage associated with such comparator, and indicating means coupled to said comparator outputs and being energized in accordance with which comparator is activated.

11. The alternator testing apparatus of claim 10, wherein said first filter means is a band-pass filter which allows passage of the ripple component and not the average component.

12. The alternator testing apparatus of claim 11, wherein the pass band of said band-pass filter is on the order of about 50 to 1,000 Hz.

13. The alternator testing apparatus of claim 10, wherein said second filter means is a low-pass filter having a cut-off frequency on the order of about 2 Hz.

14. The alternator testing apparatus of claim 10, and further comprising first gate means coupling said detector means to the signal inputs of said comparators, second gate means coupling said summing means to said divider network, each of said gate means having a control input coupled to said second filter means, said first gate means being operative to couple the first voltage to said comparators in the presence of an average component of predetermined amplitude, said second gate means being operative to couple the second voltage to said divider network in the presence of an average component of predetermined amplitude.

15. The alternator testing apparatus of claim 10, and further comprising a disabling circuit coupled to the signal inputs of said comparators and to said divider network and having a control input coupled to said second filter means, said disabling circuit being responsive to the absence of an average component of predetermined amplitude to disable said comparators.

16. The alternator testing apparatus of claim 10, wherein said indicating means is a plurality of LEDs respectively coupled to said comparator outputs.

17. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising first filter means coupled to receive the output signal for passing the ripple component, low-ripple detector means coupled to said first filter means for generating a low-ripple detector voltage representative of the amplitude of the negative-going peaks of the ripple component, high-ripple detector means coupled to said first filter means for generating a high-ripple detector voltage representative of the amplitude of the positive-going peaks of the ripple component, first summing means coupled to said low-ripple detector means and to said high-ripple detector means for adding the detector voltages therefrom and providing a first voltage representative of the peak-to-peak amplitude of the ripple component, second filter means coupled to receive the output signal for passing the average component, second summing means coupled to said first summing means and to said second filter means for generating a second voltage representative of the sum of the magnitude of the average component plus the amplitude of the ripple component, a plurality of comparators each having a signal input and a reference input and an output, said signal inputs being coupled to said first summing means, a divider network coupled to said second summing means for dividing the second voltage into a plurality of different reference voltages at a plurality of nodes in said network, said nodes being respectively coupled to said reference inputs, each comparator being activated when the first voltage exceeds the reference voltage associated with such comparator, and indicating means coupled to said comparator outputs and being energized in accordance with which comparator is activated.

18. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising first filter means coupled to receive the output signal for passing the ripple component, detector means coupled to said first filter means for generating a first voltage representative of the amplitude of the ripple component, second filter means coupled to receive the output signal for passing the average component, summing means coupled to said detector means and to said second filter means for generating a second voltage representative of the sum of the magnitude of the average component plus the amplitude of the ripple component, a plurality of display comparators each having a signal input and a reference input and an output, first gate means coupling said detector means to the signal inputs of said display comparators, second gate means coupled to said summing means, each of said gate means having a control input coupled to said second filter means, a divider network coupled to said second gate means for dividing the second voltage into a plurality of different reference voltages at a plurality of nodes in said network, said nodes being respectively coupled to said reference inputs, each display comparator being activated when the first voltage exceeds the reference voltage associated with such display comparator, indicating means coupled to said display comparator outputs and being energized in accordance with which display comparator is activated, and a control comparator coupled to said second filter means and being operative in the presence of an average component exceeding a predetermined amplitude to provide a comparator signal, the control inputs of said gate means being coupled to said control comparator, said first gate means being operative to couple the first voltage to said display comparator in the presence of the comparator signal, said second gate means being operative to couple the second voltage to said divider network in the presence of the comparator signal.

19. The alternator testing apparatus of claim 18, and further comprising a disabling circuit coupled to the signal inputs of said display comparators and to said divider network and having a control input coupled to said control comparator, said disabling circuit being responsive to the absence of the comparator signal to disable said display comparators.

20. The alternator testing apparatus of claim 18, and further comprising means coupled between said second filter means and said control comparator for amplifying and integrating the average component before coupling to said control comparator.

21. The alternator testing apparatus of claim 18, and further comprising means coupled to said comparator for giving a visual indication of the presence of the comparator signal.

22. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising circuit means for generating at a first output thereof a first voltage representative of the amplitude of the ripple component and independent of the average component and for generating at a second output thereof a second voltage representative of at least the magnitude of the average component, means for providing electrical signals representative of the ratio of the first voltage to the second voltage, and indicating means coupled to said providing means and being responsive to the electrical signals therefrom to provide information on the ratio.

23. Alternator testing apparatus for evaluating the operation of an alternator that generates an output signal having an average component and a ripple component, comprising circuit means for generating at a first output thereof a first voltage representative of the amplitude of the ripple component and independent of the average component and for generating at a second output thereof a second voltage representative of at least the magnitude of the average component, a plurality of comparators each having a signal input and a reference input and an output, said signal inputs being coupled to said first output, a divider network coupled to said second output for dividing the second voltage into a plurality of different reference voltages at a plurality of nodes in said network, said nodes being respectively coupled to said reference inputs, each comparator being activated when the first voltage exceeds the reference voltage associated with such comparator, and indicating means coupled to said comparator outputs and being energized in accordance with which comparator is activated.