Apparatus and method for detecting malfunctions in high-pressure fluid pumps

• US 6,970,793 B2
• Filed: 02/10/2003
• Issued: 11/29/2005
• Est. Priority Date: 02/10/2003
• Status: Active Grant

• Current Assignee: Flow International Corporation (Shape Technologies Group Incorporated)
• Original Assignee: Flow International Corporation (Shape Technologies Group Incorporated)
• Inventors: Pearson, Larry G., Tanuma, Aki, Wakefield, Charles M.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Washburn, Douglas N.
• Application Number:
  US10/361,975
• Publication Number:
  US 20040158419A1
• Time in Patent Office: 1,023 Days
• Field of Search: 73/15.7, 73/15.9, 73/16.8, 731/68, 737/53, 417/53, 417/63, 417/44.2, 60/394.1, 700/175, 700/282, 700/301, 702/33, 702/35, 702/41, 702/50, 702/57, 702/66, 702/71, 702/75, 702/127, 702/138, 702/182, 702/183, 702/185, 702/189, 702/193, 702/51, 702/64
• US Class Current: 702/64
• CPC Class Codes: G05B 23/0235 based on a comparison with predetermined threshold or range, e.g. "classical methods", carried out during normal operation; threshold adaptation or choice; when or how to compare with the threshold

Abstract

A fluid pump system includes a pump having a plurality of cylinders, each having an outlet port coupled to a high-pressure manifold. A pressure transducer is coupled to the manifold and configured to convert pressure levels of fluid in the manifold to a voltage signal at an output of the transducer. The system further includes a digitizer configured to convert the voltage signal from the transducer to a digital signal at a digitizer output, such that when a value of the voltage signal is less than a selected reference voltage a first digital value is produced, and when the voltage level exceeds the selected reference voltage a second digital value is produced. A diagnostic circuit having an input coupled to the digitizer output is configured to detect malfunctions of the pump based upon characteristics of the digital signal.

Claims

1. A device, comprising:

means for converting pressure levels of a high-pressure manifold of a fluid pump having a plurality of cylinders to a proportionate voltage signal; and

means for detecting a malfunction in a component of one of the plurality of cylinders by examination of an AC component of the voltage signal, the detecting means including means for comparing the AC component of the voltage signal to a reference frequency, the detecting means further including means for converting the AC component of the voltage sianal to a digital signal for comparison to the reference frequency.

2. The device of claim 1 wherein the detecting means includes means for comparing the frequency of the AC component of the voltage signal to a reference frequency.

3. The device of claim 1 wherein the reference frequency is equal to a number of revolutions per second of the fluid pump multiplied by the number of cylinders of the pump.

4. A device comprising:

means for converting pressure levels of a high-pressure manifold of a fluid pump having a plurality of cylinders to a proportionate voltage signal; and

means for detecting a malfunction in a component of one of the plurality of cylinders by examination of an AC component of the voltage signal, the detecting means including means for comparing the AC component of the voltage signal to a reference frequency, the detecting means further including means for correlating a peak of the reference frequency to a compression stroke of one of the plurality of cylinders.

5. A device, comprising:

a pressure transducer configured to be coupled to a high-pressure manifold of a multi-cylinder pump and provide an output voltage signal proportionate to a pressure input;

a digitizer circuit having an input coupled to the output of the transducer and configured to convert an AC component of the voltage signal to a digital signal, in which a first digital value is supplied at a digitizer output while the voltage signal is below a selected threshold voltage, and a second digital value is supplied at the digitizer output while the voltage signal is above the selected threshold voltage; and

a diagnostic circuit having an input coupled to the digitizer output and configured to diagnose malfunctions of the pump based upon the digital signal.

6. The device of claim 5 wherein the diagnostic circuit is configured to compare the frequency of the digital signal to a reference frequency.

7. The device of claim 6 wherein the reference frequency is equal to a number of revolutions per second of a motor driving the pump multiplied by the number of cylinders of the pump.

8. The device of claim 6 wherein the diagnostic circuit is configured to indicate a malfunction when the frequency of the digital signal is not equal to the reference frequency.

9. The device of claim 8 wherein the diagnostic circuit is configured to indicate a first category of malfunction when the frequency of the digital signal is lower than the reference frequency but higher than a selected fraction of the reference frequency, and to indicate a second category of malfunction when the frequency of the digital signal is lower than the selected fraction of the reference frequency.

10. The device of claim 5 wherein the threshold voltage represents an acceptable pressure level of the manifold during a pressurizing stroke of the pump.

11. The device of claim 10 wherein the threshold voltage is selectable according to a desired sensitivity of the diagnostic circuit.

12. The device of claim 5 wherein the diagnostic circuit is configured to correlate pressurizing strokes of each cylinder of the pump to corresponding peaks of a reference frequency, to compare, peak for peak, the reference frequency with the digital signal, and to indicate, when the reference frequency exhibits a peak for which no corresponding peak is produced in the digital signal, a malfunction in the cylinder corresponding to the exhibited peak.

13. The device of claim 5 wherein the digital signal is an alternating signal.

14. A system, comprising:

a pump having a plurality of cylinders, each of the cylinders having an outlet port;

a high-pressure manifold having a plurality of inlets, each of the inlets being coupled to one of the outlet ports;

a pressure transducer having an input sensor coupled to the manifold and configured to convert pressure levels of fluid in the manifold to a voltage signal at an output of the transducer;

a digitizer having an input coupled to the output of the transducer and configured to convert the voltage signal from the transducer to a digital signal at a digitizer output, such that when a value of the voltage signal is less than a selected reference voltage a first digital value is produced and when the voltage level exceeds the selected reference voltage a second digital value is produced; and

a diagnostic circuit having an input coupled to the digitizer output and configured to detect malfunctions of the pump based upon the digital signal.

15. The system of claim 14 wherein the diagnostic circuit is configured to compare a frequency of the digital signal with a reference frequency.

16. The system of claim 15 wherein the pump comprises a crankshaft to which is linked a plurality of drive rods, one for each of the plurality of cylinders, and wherein the reference frequency is derived from the revolutions per second of the crankshaft multiplied by the number of cylinders in the plurality of cylinders.

17. The system of claim 15 wherein the diagnostic circuit is configured to indicate a malfunction when the frequency of the digital signal does not match the reference frequency.

18. The system of claim 14, further comprising a shut-off circuit coupled to an output of the diagnostic circuit, configured to shut off power to the pump in the event that a malfunction is detected.

19. The system of claim 16, further comprising a motor coupled to the crankshaft and configured to provide power thereto.

20. The system of claim 14, further comprising a tool coupled to an output line of the high-pressure manifold and configured to utilize pressurized fluid from the manifold.

21. The system of claim 20 wherein the tool is a cutting head, configured to direct a high-pressure stream of fluid through a nozzle to cut selected material.

22. The system of claim 20, further comprising an additional tool coupled to an additional output line of the manifold.

23. A method, comprising:

converting pressure levels at a high-pressure manifold of a multi-cylinder pump to a proportionate voltage signal;

detecting a malfunction in a component of one of the plurality of cylinders by converting an AC component of the voltage signal to a digital signal; and

comparing a frequency of the digital signal to a reference frequency.

24. The method of claim 23 wherein the converting step is performed by a pressure transducer.

25. The method of claim 23 wherein the reference frequency is correlated to a total number of compression strokes of all of the plurality of cylinders of the multi-cylinder pump, per second.

27. The method of claim 25 wherein the detecting a malfunction step includes:

correlating compression strokes of each of the cylinders with corresponding peaks of the reference frequency;

comparing, peak for peak, the digital signal frequency with the reference frequency;

detecting a peak of the reference frequency for which no corresponding peak is present in the digital signal frequency; and

indicating the cylinder corresponding to the detected peak as including the malfunctioning component.

26. A method, comprising:

converting fluid pressure to a voltage signal;

comparing the voltage signal to a reference voltage;

supplying a first digital value as an output signal while the voltage signal exceeds the reference voltage;

supplying a second digital value as the output signal while the voltage signal does not exceed the reference voltage; and

comparing a frequency of the output signal to a reference frequency.