Method of monitoring deterioration of lubricating oil and device therefore

• US 8,224,600 B2
• Filed: 10/16/2008
• Issued: 07/17/2012
• Est. Priority Date: 02/22/2008
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Heavy Industries, Ltd.
• Original Assignee: Mitsubishi Heavy Industries, Ltd.
• Inventors: Kaga, Junichi, Akiyama, Yo, Yano, Akihiko
• Primary Examiner(s): Nghiem, Michael
• Application Number:
  US12/252,810
• Publication Number:
  US 20090216471A1
• Time in Patent Office: 1,370 Days
• Field of Search: 702/65
• 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, the method comprising:

obtaining and storing, beforehand, a predetermined correlation between relative permittivity and TBN (total base number) of the lubricating oil;

applying high-frequency alternating voltage between a pair of electrodes located in the oil path;

measuring values of applied voltage and resulting electric current;

calculating relative permittivity of the oil based on the measured values of voltage and current;

determining an actual TBN of the oil from the predetermined correlation between relative permittivity and TBN of the oil; and

judging deterioration of the oil based on the determined actual TBN,

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.

2. 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, comprising:

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

processing means for judging deterioration of oil based on measurement of the amperemeter and voltmeter, the processing means including a memory section for storing data of predetermined correlation between relative permittivity and TBN (total base number) of the lubricating oil, a relative permittivity calculating section for calculating an actual 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 the calculated actual relative permittivity based on the predetermined correlation between relative permittivity and TBN of the oil,

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.

3. A device for monitoring deterioration of lubricating oil according to claim 2, wherein a first member having high permittivity and able to generate ultrasonic vibration is attached only to one of the pair of electrodes so that the first member covers an electrode plane of the one of the pair of electrodes with even thickness so that the lubricating oil flows between the first member and the other electrode or further to the first member being attached to the one of the pair of electrodes, a second member of high permittivity is attached to the other of the pair of electrodes so that the second member covers an electrode surface of the other of the pair of electrodes with even thickness so that the lubricating oil flows between the first and second members.

4. 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.

5. A device for monitoring deterioration of lubricating oil according to claim 2, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.

6. A device for monitoring deterioration of lubricating oil according to claim 2, 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.

7. A device for monitoring deterioration of lubricating oil according to claim 2, wherein a first member of high permittivity is attached only to one of the pair of electrodes so that the first member covers an electrode plane of the one of the pair of electrodes with even thickness so that the lubricating oil flows between the first member and the other electrode or further to the first member being attached to the one of the pair of electrodes, a second member of high permittivity is attached to the other of the pair of electrodes so that the second member covers an electrode surface of the other of the pair of electrodes with even thickness so that the lubricating oil flows between the first and second members.

8. A device for monitoring deterioration of lubricating oil according to claim 2, 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 2, 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 9, wherein a first member of high permittivity is attached only to one of the pair of electrodes so that the first member covers an electrode plane of the one of the pair of electrodes with even thickness so that the lubricating oil flows between the first member and the other electrode or further to the first member being attached to the one of the pair of electrodes, a second member of high permittivity is attached to the other of the pair of electrodes so that the second member covers an electrode surface of the other of the pair of electrodes with even thickness so that the lubricating oil flows between the first and second members.

11. A device for monitoring deterioration of lubricating oil according to claim 9, wherein a first member having high permittivity and able to generate ultrasonic vibration is attached only to one of the pair of electrodes so that the first member covers an electrode plane of the one of the pair of electrodes with even thickness so that the lubricating oil flows between the first member and the other electrode or further to the first member being attached to the one of the pair of electrodes, a second member of high permittivity is attached to the other of the pair of electrodes so that the second member covers an electrode surface of the other of the pair of electrodes with even thickness so that the lubricating oil flows between the first and second members.

12. A device for monitoring deterioration of lubricating oil according to claim 9, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.

13. A device for monitoring deterioration of lubricating oil via an oil path to rotating and sliding parts of a gas engine for driving an electric generator, comprising:

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

processing means for judging deterioration of oil based on measurement of the amperemeter and voltmeter, the processing means including a memory section for storing data of predetermined correlation between relative permittivity and TBN (total base number) of the lubricating oil, a relative permittivity calculating section for calculating an actual 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 the calculated actual relative permittivity based on the predetermined correlation between relative permittivity and TBN of the oil,

wherein a first member of high permittivity is attached only to one of the pair of electrodes so that the first member covers an electrode plane of the one of the pair of electrodes with even thickness so that the lubricating oil flows between the first member and the other electrode or further to the first member being attached to the one of the pair of electrodes, a second member of high permittivity is attached to the other of the pair of electrodes so that the second member covers an electrode surface of the other of the pair of electrodes with even thickness so that the lubricating oil flows between the first and second members.

14. A device for monitoring deterioration of lubricating oil according to claim 13, wherein at least one of the first and second members generates ultrasonic vibration.

15. A device for monitoring deterioration of lubricating oil according to claim 13, wherein a temperature regulating means is located upstream of the pair of electrodes located in the oil path.