Method of monitoring deterioration of lubricating oil and device therefore

• US 20090216471A1
• Filed: 10/16/2008
• Published: 08/27/2009
• Est. Priority Date: 02/22/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Heavy Industries, Ltd.
• Original Assignee: Mitsubishi Heavy Industries, Ltd.
• Inventors: Kaga, Junichi, AKIYAMA, Yo, Yano, Akihiko
• Granted Patent: US 8,224,600 B2
• Time in Patent Office: Days
• US Class Current: 702/65
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26
• CPC Class Codes: G01N 33/2876 Total acid number

Abstract

A method of monitoring deterioration of lubricating oil and a device therefore capable of judging deterioration of the oil with high accuracy suppressing measurement error due to mixing of foreign matter in the oil. Correlation between relative permittivity and TBN (total base number) of the lubricating oil is obtained beforehand (step S1), electric current and voltage are measured (step S2) when high-frequency voltage is applied between a pair of electrodes located in an oil path in a gas engine, permittivity of the oil is detected (step S3) based on the measurement of current and voltage, TBN of the oil is obtained (step S4) from the correlation between relative permittivity and TBN, and deterioration of the oil is judged by the obtained value of TBN.

Claims

1. A method of monitoring deterioration of lubricating oil

supplied via an oil path to rotating and sliding parts of a gas engine for driving an electric generator, wherein

correlation between relative permittivity and TBN (total base number) of the lubricating oil is obtained beforehand,

a pair of electrodes is located in the oil path, high-frequency alternating voltage is applied between the electrodes, values of applied voltage and resulting electric current are measured, and relative permittivity of the oil is calculated based on the measured values of voltage and current, TBN of the oil is determined from the correlation between relative permittivity and TBN of the oil, and deterioration of the oil is judged based on the determined TBN.

2. A method of monitoring deterioration of lubricating oil

according to claim 1, wherein a permissible upper limit of relative permittivity of the lubricating oil is prescribed to correspond to a permissible lower limit of TBN, and that the oil is deteriorated is alarmed when detected relative permittivity reaches or exceeds the permissible upper limit of relative permittivity.

3. A device for monitoring deterioration of lubricating oil supplied via an oil path to rotating and sliding parts of a gas engine for driving an electric generator, wherein the device comprises a pair of electrodes facing each other with a certain distance and located in the oil path, a high-frequency alternating power source for applying high-frequency voltage between the electrodes, an amperemeter for measuring electric current flowing between the electrodes, a voltmeter for measuring voltage between the electrodes, and a processing means for judging deterioration of oil based on measurement of the amperemeter and voltmeter, the processing means comprising a memory section for storing data of correlation between relative permittivity and TBN (total base number) of the lubricating oil, a relative permittivity calculating section for calculating relative permittivity of the oil from the measured values of voltage and current, and an oil deterioration judging section for judging deterioration of the oil from calculated relative permittivity based on the correlation between relative permittivity and TBN of the oil.

4. A device for monitoring deterioration of lubricating oil according to claim 3, wherein a permissible upper limit of relative permittivity of the lubricating oil is prescribed to correspond to a permissible lower limit of TBN, and an alarm device is provided which alarms that the oil is deteriorated when the calculated relative permittivity reaches or exceeds the permissible upper limit of relative permittivity.

5. A device for monitoring deterioration of lubricating oil according to claim 3, wherein an ultrasonic transducer is connected to at least one of the pair of electrodes so that ultrasonic vibration produced by the transducer by applying voltage intermittently to the transducer is propagated to the electrode to which the transducer is connected and the electrode is cleaned by the ultrasonic vibration.

6. A device for monitoring deterioration of lubricating oil according to claim 3, wherein a member of high permittivity is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

7. A device for monitoring deterioration of lubricating oil according to claim 3, wherein a member having high permittivity and able to generate ultrasonic vibration is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

8. A device for monitoring deterioration of lubricating oil according to claim 3, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.

9. A device for monitoring deterioration of lubricating oil according to claim 4, wherein an ultrasonic transducer is connected to at least one of the pair of electrodes so that ultrasonic vibration produced by the transducer by applying voltage intermittently to the transducer is propagated to the electrode to which the transducer is connected and the electrode is cleaned by the ultrasonic vibration.

10. A device for monitoring deterioration of lubricating oil according to claim 4, wherein a member of high permittivity is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

11. A device for monitoring deterioration of lubricating oil according to claim 5, wherein a member of high permittivity is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

12. A device for monitoring deterioration of lubricating oil according to claim 4, wherein a member having high permittivity and able to generate ultrasonic vibration is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

13. A device for monitoring deterioration of lubricating oil according to claim 5, wherein a member having high permittivity and able to generate ultrasonic vibration is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

14. A device for monitoring deterioration of lubricating oil according to claim 6, wherein a member having high permittivity and able to generate ultrasonic vibration is attached to at least one of the pair of electrodes so that the member covers an electrode plane of the at least one of the electrodes with even thickness so that the lubricating oil flows between the member and the other electrode or between the members when the member is attached to both the electrodes.

15. A device for monitoring deterioration of lubricating oil according to claim 4, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.

16. A device for monitoring deterioration of lubricating oil according to claim 5, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.

17. A device for monitoring deterioration of lubricating oil according to claim 6, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.

18. A device for monitoring deterioration of lubricating oil according to claim 7, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.