GB1603190A - Apparatus for detecting faults or defects in moving machine parts - Google Patents
Apparatus for detecting faults or defects in moving machine parts Download PDFInfo
- Publication number
- GB1603190A GB1603190A GB15968/78A GB1596878A GB1603190A GB 1603190 A GB1603190 A GB 1603190A GB 15968/78 A GB15968/78 A GB 15968/78A GB 1596878 A GB1596878 A GB 1596878A GB 1603190 A GB1603190 A GB 1603190A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- signal
- oscillator
- pick
- defects
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M13/00—Testing of machine parts
- G01M13/04—Bearings
- G01M13/045—Acoustic or vibration analysis
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Description
(54) APPARATUS FOR DETECTING FAULTS OR
DEFECTS IN MOVING MACHINE PARTS
(71) We, SKF INDUSTRIAL
TRADING AND DEVELOPMENT
COMPANY B.V. a Company organised and existing under the laws of the Kingdom of the Netherlands, of Plattenburgerweg, P.O.
Box 50, Nieuwegein, the Netherlands, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention concerns apparatus for detecting faults or defects in moving machine parts.
The invention provides apparatus for detecting faults or defects in moving machine parts comprising a non-acoustic pick-up for converting mechanical vibrations of a selected part of the machine into an electrical signal at the frequency of vibration, an oscillator for generating a reference signal at a predetermined frequency, a mixing or multiplying device connected to the pick-up and oscillator for combining the said signals to produce signals at the sum and difference frequencies, a low-pass filter connected to the mixing or multiplying device and arranged to discriminate against the signal of the sum frequency and to pass the signal of the difference frequency, and an indicating instrument connected to the lowpass filter to respond to the signal of the difference frequency.
The frequency of the oscillator signal may be higher than the frequency of the pick-up signal.
The indicating instrument may include a peak detector responsive to the signal of the difference frequency.
The oscillator may be tunable to adjust the frequency of the reference signal.
An embodiment of apparatus according to the invention will now be described by way of example and with reference to the accompanying drawings which is a diagram of the embodiment.
A piezo electric pick-up 1 is used to convert the mechanical vibrations of the moving machine part being tested, for example a bearing, into an electrical signal at the frequency fl of the vibration. The signal is then amplified in a pre-amplifier 2 and is then fed to a mixing or multiplying device 3. Also connected to the device 3 is a tunable oscillator 4 which generates a reference signal at a predetermined frequency f2 somewhat higher than the frequency of the pick-up signal.The mixing or multiplying device 3 combines the said signals to produce signals with a difference frequency f2-f1 and with a sum frequency f1+f2. A low-pass filter 5 is connected to the device 3 and is arranged to discriminate against the signal with the sum frequency f1+f2 and to pass the signal with the difference frequency f2-f1 to a peak detector 6 to which the filter 5 is connected.
The output from the detector 6 is then fed to an indicating instrument 7 such as a simple dial from which the magnitude of the fault or defect can be subsequently interpreted or measured.
An advantage of apparatus according to the invention is that the difference frequency f2-f1 is a low frequency making only a small demand of the analysis apparatus comprising peak detector 6 and indicating instrument 7 when compared to the demand when operating in the high frequencies. A non-critical low-pass filter 5 is used to discriminate against the signal with the sum frequency and to pass the signal with the difference frequency from the mixing and multiplying device 3. The magnitude of the difference frequency is thus indicative of the magnitude of the fault in the moving machine part, such as a bearing, under investigation.
A further advantage is that the resonant frequency of the signal from the pick-up 1 is not critical, since the oscillator 4 can be tuned to any desired frequency.
Furthermore the apparatus is, because of its selective nature, insensitive to interference signals picked up by~the pick-up 1 or the pre-amplifier 2. Also the apparatus is quite reliable since a peak detector is employed.
WHAT WE CLAIM IS:
1. Apparatus for detecting faults or defects in moving machine parts comprising a non-acoustic pick-up for converting mechanical vibrations of a selected part of the machine into an electrical signal at the frequency of vibration, an oscillator for generating a reference signal at a predetermined frequency, a mixing or multiplying device connected to the pick-up and oscillator for combining the said signals to produce signals at the sum and difference frequencies, a low-pass filter connected to the mixing or multiplying device and arranged to discriminate against the signal of the sum frequency and to pass the signal of the difference frequency, and an indicating instrument connected to the lowpass filter to respond to the signal of the difference frequency.
2. Apparatus as claimed in claim 1 wherein the frequency of the oscillator signal is higher than the frequency of the pick-up signal.
3. Apparatus as claimed in claim 1 or 2 wherein the indicating instrument includes a peak detector responsive to the signal of the difference frequency.
4. Apparatus as claimed in any preceding claim wherein the oscillator is tunable to adjust the frequency of the reference signal.
5. Apparatus for detecting faults or defects in moving machine parts substantially as herein described with reference to and as shown in the accompanying drawing.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (5)
1. Apparatus for detecting faults or defects in moving machine parts comprising a non-acoustic pick-up for converting mechanical vibrations of a selected part of the machine into an electrical signal at the frequency of vibration, an oscillator for generating a reference signal at a predetermined frequency, a mixing or multiplying device connected to the pick-up and oscillator for combining the said signals to produce signals at the sum and difference frequencies, a low-pass filter connected to the mixing or multiplying device and arranged to discriminate against the signal of the sum frequency and to pass the signal of the difference frequency, and an indicating instrument connected to the lowpass filter to respond to the signal of the difference frequency.
2. Apparatus as claimed in claim 1 wherein the frequency of the oscillator signal is higher than the frequency of the pick-up signal.
3. Apparatus as claimed in claim 1 or 2 wherein the indicating instrument includes a peak detector responsive to the signal of the difference frequency.
4. Apparatus as claimed in any preceding claim wherein the oscillator is tunable to adjust the frequency of the reference signal.
5. Apparatus for detecting faults or defects in moving machine parts substantially as herein described with reference to and as shown in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7704347A NL7704347A (en) | 1977-04-21 | 1977-04-21 | DETECTION SYSTEM AND THE DETECTION DEVICE IN WHICH THE SYSTEM IS INSTALLED. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1603190A true GB1603190A (en) | 1981-11-18 |
Family
ID=19828408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB15968/78A Expired GB1603190A (en) | 1977-04-21 | 1978-04-21 | Apparatus for detecting faults or defects in moving machine parts |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS53132394A (en) |
| DE (1) | DE2817625C2 (en) |
| FR (1) | FR2388274A1 (en) |
| GB (1) | GB1603190A (en) |
| IT (1) | IT1112653B (en) |
| NL (1) | NL7704347A (en) |
| SE (1) | SE438047C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0227138A1 (en) * | 1985-11-28 | 1987-07-01 | SKF Industrial Trading & Development Co, B.V. | Means for detecting faults or defects in moving machine parts |
| GB2209397A (en) * | 1987-10-02 | 1989-05-10 | Servo Corp Of America | Acoustic detection of bearing defects |
| US5679900A (en) * | 1992-12-08 | 1997-10-21 | Skf Condition Monitoring | Envelope enhancement system for detecting paper machine press section anomalous vibration measurements |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU949342A1 (en) * | 1977-12-05 | 1982-08-07 | Специальное Опытное Проектно-Конструкторско-Технологическое Бюро Сибирского Отделения Всесоюзной Ордена Ленина Академии Сельскохозяйственных Наук Им.В.И.Ленина | Method and device for detecting flaws in cyclic action objects |
| JPS5653422A (en) * | 1979-10-08 | 1981-05-13 | Hitachi Ltd | Diagnosis device for bearing abnormality |
| DE3049628C2 (en) * | 1980-12-31 | 1982-10-21 | Basf Ag, 6700 Ludwigshafen | Method for monitoring the formation and progression of cracks in machine parts and components as well as a device for carrying out the method |
| RU2495395C1 (en) * | 2012-04-27 | 2013-10-10 | Федеральное государственное унитарное предприятие "Научно-производственный центр газотурбостроения "Салют" | Method of diagnosing twin-shaft gas turbine engine transmission |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE881836C (en) * | 1951-02-09 | 1953-07-02 | Kurt Dr Bruecker-Steinkuhl | Frequency analyzer based on the search tone analysis method for coarse and fine analysis |
| DE1077444B (en) * | 1957-04-24 | 1960-03-10 | Rohde & Schwarz | Arrangement for the analysis of vibrations |
| US3393557A (en) * | 1967-06-29 | 1968-07-23 | Texaco Inc | Apparatus for measuring selected engine vibration characteristics |
| US3971249A (en) * | 1975-03-28 | 1976-07-27 | Sun Oil Company Of Pennsylvania | Mechanical testing system |
-
1977
- 1977-04-21 NL NL7704347A patent/NL7704347A/en not_active Application Discontinuation
-
1978
- 1978-01-30 IT IT19760/78A patent/IT1112653B/en active
- 1978-04-13 SE SE7804165A patent/SE438047C/en not_active IP Right Cessation
- 1978-04-19 FR FR7811607A patent/FR2388274A1/en active Granted
- 1978-04-20 JP JP4602178A patent/JPS53132394A/en active Pending
- 1978-04-21 GB GB15968/78A patent/GB1603190A/en not_active Expired
- 1978-04-21 DE DE2817625A patent/DE2817625C2/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0227138A1 (en) * | 1985-11-28 | 1987-07-01 | SKF Industrial Trading & Development Co, B.V. | Means for detecting faults or defects in moving machine parts |
| US4768380A (en) * | 1985-11-28 | 1988-09-06 | Skf Engineering & Research Centre, B.V. | Method and means for detecting faults or defects in moving machine parts |
| GB2209397A (en) * | 1987-10-02 | 1989-05-10 | Servo Corp Of America | Acoustic detection of bearing defects |
| GB2209397B (en) * | 1987-10-02 | 1991-12-11 | Servo Corp Of America | On-line acoustic detection of bearing defects |
| US5679900A (en) * | 1992-12-08 | 1997-10-21 | Skf Condition Monitoring | Envelope enhancement system for detecting paper machine press section anomalous vibration measurements |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2817625C2 (en) | 1986-03-27 |
| SE7804165L (en) | 1978-10-22 |
| JPS53132394A (en) | 1978-11-18 |
| DE2817625A1 (en) | 1978-10-26 |
| SE438047C (en) | 1987-04-05 |
| NL7704347A (en) | 1978-10-24 |
| SE438047B (en) | 1985-03-25 |
| IT7819760A0 (en) | 1978-01-30 |
| IT1112653B (en) | 1986-01-20 |
| FR2388274B1 (en) | 1984-09-14 |
| FR2388274A1 (en) | 1978-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930421 |