GB2219657A - Method and apparatus for monitoring the tension in an elongate flexible member - Google Patents
Method and apparatus for monitoring the tension in an elongate flexible member Download PDFInfo
- Publication number
- GB2219657A GB2219657A GB8813630A GB8813630A GB2219657A GB 2219657 A GB2219657 A GB 2219657A GB 8813630 A GB8813630 A GB 8813630A GB 8813630 A GB8813630 A GB 8813630A GB 2219657 A GB2219657 A GB 2219657A
- Authority
- GB
- United Kingdom
- Prior art keywords
- radiation
- flexible member
- tension
- natural frequency
- monitoring
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/04—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands
- G01L5/042—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands by measuring vibrational characteristics of the flexible member
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
The apparatus for monitoring the tension in a vibrating flexible elongate member (4) includes a source of radiation (5) and a detector (8) for detecting radiation reflected from the flexible member. Variations in the intensity of the detected radiation arising from a variation in the path length of the detected radiation are sensed, and the natural frequency of vibration of the flexible member (4) is ascertained therefrom. The tension in the flexible member (4) is determined from the ascertained frequency value.
Description
Method and apparatus for monitoring the tension in an elongate flexible member.
This invention relates to a method and apparatus for monitoring the tension in an elongate flexible member, and in particular for monitoring the tension in a belt.
Belts are used in automobile engines and elsewhere both for the transmission of power and for maintaining synchronisation between different moving shafts. For efficient operation such belts must be maintained at the correct tension. If, for example, the belt is too loose then slipping or jumping of the belt may occur, whereas if it is too tight excessive wear may be caused in bearings.
At present it is normal practice to set the tension when the belt is stationary. A method for setting the tension is described in our
International patent application, No. PCT/GB87/00171.
Such a method is not, however, particularly well suited for use with a permanently-installed tension monitoring device, or for measuring the tension in a moving belt. Further, when the machinery is running and the belt is being driven around the pulleys, creep ma,y occur in the belt causing the tension to decrease. In an attempt to compensate for this expected decrease in tension, it is possible to set the belt initially at too high a tension, so that after the belt has been running for some time the tension will approach the desired value. Such a method does not, however, enable the helt tension to be set accurately.
It is an object of the invention to provide an improved apparatus and method for monitoring the tension in an elongate flexible member. It is desirable that such a method of monitoring tension should be able to operate without affecting the operation of the flexible member in any way, and should be sufficiently robust and reliable for permanent installation as part of a tension-monitoring device. It is also desirable that such a method should be capable of monitoring the tension in a moving elongate flexible member.
According to the present invention there is provided a method of monitoring the tension in a vibrating elongate flexible member including the steps of directing radiation onto the flexible member, detecting at least some of the radiation reflected from the flexible member, sensing variation in the intensity of the detected radiation arising from a variation in the path length of the detected radiation, and thereby ascertaining the natural frequency of vibration of the flexible member. ,
The term "natural frequency" as used herein refers to any frequency at which the flexible member will naturally vibrate.In the normal case this will be the fundamental resonant frequency but it is possible to arrange for the frequencies of the harmonics of the fundamental frequency to be ascertained.
Such a method allows continuous monitoring of the tension in a moving elongate flexible member, without there being any contact between the flexible member and the tension monitor. The tension monitor does not, therefore, interfere with the operation of the flexible member. Further, as the tension monitor need not have any moving mechanical parts it can be extremely robust and reliable, and it can be installed permanently in, for example, the engine compartment of a car as part of an engine management or monitoring system for monitoring the tension in a drive belt, and can provide a warning should the tension in the drive belt depart from a predetermined range.
Preferably, the elongate flexible member is part of a drive belt and the ends of the part of the belt which vibrates are defined by points of engagement of the belt with the pulleys.
The tension may be monitored while the drive belt is moving, thereby allowing the tension to be monitored whilst the belt is in use. If the drive belt is being driven, the part which vibrates is not,0of course, any single segment of the belt, but is that part which is at any particular instant between the pulleys.
Advantageously, vibrations are caused by the belt being driven around the pulleys, thereby avoiding the need for a separate vibration generator.
Alternatively, the elongate flexible member may be stationary apart from its vibrating movement, the vibrations being caused by, for example, striking the flexible member.
The radiation directed onto the flexible member may be modulated, in order to distinguish it from ambient radiation.
Preferably, the signal representing the output of the radiation detector is filtered to remove signals outside a predetermined frequency band,which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and the frequency of the filtered signal is measured to ascertain the actual value of the natural frequency.
It is particularly advantageous to use such a method when measuring the tension in a moving drive belt, which is liable to vibrate at a multitude of different frequencies because, even though the precise value of the natural frequency is not known, most spurious frequencies can be filtered out.
Advantageously, the incident radiation is directed to fall entirely upon the flexible member, thereby reducing interference from reflections of the radiation from other objects, and preferably the incident radiation is propagated as a substantially parallel beam.
Advantageously, the radiation is electromagnetic radiation, and is preferably visible light or infrared radiation.
The present invention further provides an apparatus for monitoring the tension in a vibrating flexible elongate member including a source of radiation, means for detecting at least some of the radiation reflected from the flexibie member, means for sensing variation in the intensity of the detected radiation arising from a variation in the path length of the detected radiation, and means for ascertaining the natural frequency of vibration of the flexible member from the variation in intensity of the detected radiation.
The apparatus may include a buffer means for temporarily storing the signal representing the output of the radiation detector.
A fibre optic tube may be provided for guiding the radiation from the source and/or to the detector.
An end of the or each fibre optic tube may be bevelled to refract the incident and/or the reflected radiation.
The radiation source may include a laser.
The present invention further provides a drive belt system including a drive belt arranged to be driven around a plurality oE pulleys and an apparatus as described above for monitoring the tension in the drive belt.
The drive belt system may include means for providing a warning whenever the tension in the drive belt departs from a predetermined range.
The present invention yet further provides a motor-driven vehicle including a drive belt system as described above.
According to the present invention there is further provided a method of monitoring the tension in a vibrating elongate flexible member in which the vibrations of the flexible member are detected, the signal representing the output of the vibration detector is filtered to remove signals outside a predetermined frequency band, which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and the frequency of the filtered signal is measured to ascertain the actual value of the natural frequency.
According to the present invention there is further provided an apparatus for monitoring the tension in a vibrating elongate flexible member including means for detecting the vibrations of the flexible member, means for filtering the signal representing the output of the vibration detector to remove signals outside a predetermined frequency band, which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and means for measuring the frequency of the filtered signal to ascertain the actual value of the natural frequency.
Certain embodiments of the invention will now be described by way of example with reference to the accompanying drawings, of which:
Fig. 1 shows a part of a drive belt system;
Fig. 2 shows, diagrammatically, the arrangement
of a transmitter and a detector in
relation to the drive belt;
Fig. 3 is a block diagram of an electronic
frequency-sensing circuit, and
Fig. 4 shows an alternative form of the
transmitter and detector arrange
ment shown in Fig. 2.
Figure 1 shows a part of a drive belt system, indicated generally by the reference numeral 1, comprising a drive belt 2 arranged to be driven around pulleys 3.
As the belt 2 is driven, small, but unavoidable, irregularities in the driving speed and in the geometrical configurations of the various components of the system subject the belt to a continuous stream of impulse disturbances which cause portions of the belt, such as that indicated by preference numeral 4, between the pulleys 3, to vibrate transversely, as indicated by the dotted lines shown in Fig. 1. A significant component of these transverse vibrations occurs at the natural frequency of the vibrating portion 4 of the belt 2 and, as the natural frequency varies as a function of the tension in the belt (the mass per unit length, and the length of the vibrating portion of the belt being constant), ascertaining the natural frequency allows the tension in the belt to be calculated.
An arrangement for sensing the vibrations of the vibrating belt portion 4 is illustrated in Fig. 2.
A transmitter 5 directs a beam of light 6 onto a flat surface of the belt portion 4 and at least some of the reflected light 7 is detected by a detector 8.
As the belt 2 is driven round the pulleys 3, various irregularities in the drive speed and the geometrical configuration of the pulleys etc. cause the portion to vibrate towards and away from the transmitter 5 and the detector 8, thereby affecting the path length of the light passing from the transmitter to the detector.
As the intensity of the light reaching the detector varies with the changing path length, by monitoring the intensity of the detected light the vibrations of the belt may be sensed.
In order to reduce interference from ambient light the light source in the transmitter 5 is modulated at high frequency, thereby distinguishing the incident light from any ambient light which reaches the detector 8.
The output of the detector 8 is connected to an electronic frequency-sensing circuit, which is shown in Fig. 3. A signal 9, representative of the output of the detector 8 is fed first to a buffer 10 which stores the data temporarily before passing it on to a demodulator 11. The demodulator 11 rectifies and smoothes the signal, removing the modulated carrier signal, and the demodulated signal 12, which. represents the actual vibration of the belt portion 4 and which contains a multitude of different frequencies is passed to a filter 13. The filter 13 passes only a narrow band of frequencies, the width of the band being determined by the range of frequencies in which the natural frequency of vibration of the belt portion 4 is expected to lie.The filter admits only frequencies corresponding to the natural frequency of the belt portion 4 when the tension in the belt 2 is within a predetermined range of the corect tension: for example when the tension is within + 5 % of the correct tension. By this method spurious frequencies of vibration of the belt portion 4 may be removed, allowing the natural frequency to be ascertained, provided the belt tension is within the at ore mentioned range.
The filtered signal 14 is then squared-up by a squaring circuit 15 and is passed to a micro-processor 16 which compares the signal with a signal of known frequency from an oscillator 17, thereby measuring the natural frequency of the belt portion 4.
As shown in Fig. 4, the transmitter 5 and the detector 8 may be connected to a light-guide device 18 comprising two fibre optic tubes 19 arranged side-by side to guide the incident and reflected beams of light 6 and 7 to and from the belt portion 4. The ends 19a of the fibre optic tubes 19 are bevelled to refract the incident and reflected beams 6 and 7 towards a single point 20 on the belt surface, thereby maximizing the proportion of the reflected light reaching the detector 8. The light-guide device 18 can also be positioned very close to the surface of the belt portion 4, thereby increasing the sensitivity of the device to vibrations of small amplitude.
Various other embodiments of the invention are possible: for example, another form of electromagnetic radiation, such as infra-red,may be used, and a laser may be employed as the light source in the transmitter 5. Alternative, other types of radiation, such as ultrasound, may be used.
A simple read-out of the detected natural frequency may be provided or, alternatively, a second micro-processor may be incorporated to calculate, and to provide a read-out of, the tension in the belt.
The method may also be used on a stationary belt, with the vibrations induced by, for example, striking the belt, or it may be used to monitor the tension in'any other vibrating flexible elongate member.
Claims (31)
1. A method of monitoring the tension in a vibrating elongate flexible member including the steps of directing radiation onto the flexible member, detecting at least some of the radiation reflected from the flexible member, sensing variation in the intensity of the detected radiation arising from a variation in the path length of the detected radiation, and thereby ascertaining the natural frequency of vibration of the flexible member.
2. A method according to claim 1 in which the elongate flexible member is part of a drive belt and the ends of the part of the belt which vibrates are defined by points of engagement of the belt with the pulleys.
3. A method according to claim 2 in which the tension is monitored while the drive belt is moving.
4. A method according to claim 3 in which the vibrations are caused by the belt being driven around the pulleys.
5. A method according to claim 1 in which the elongate flexible member is stationary, apart from its vibrating movement.
6. A method according to any preceding claim in which the radiation directed onto the flexible member is modulated.
7. A method according to any preceding claim in which the signal representing the output of the radia tion detector is filtered to remove signals outside a predetermined frequency band, which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and the frequency of the filtered signal is measured to ascertain the actual value of the natural frequency.
8. A method according to any preceding claim in which the incident radiation is directed to fall entirely upon the flexible member.
9. A method according to any preceding claim in which the incident radiation is propogated as a substantially parallel beam.
10. A method according to any preceding claim in which the radiation is electromagnetic radiation.
11. A method according to claim 10 in which the radiation is visible light.
12. A method according to claim 10, in which the radiation is infra-red radiation.
13. An apparatus for monitoring the tension in a vibrating flexible elongate member including a source of radiation, means for detecting at least some of the radiation reflected from the flexible member, means for sensing variation in the intensity of the detected radiation arising from a variation in the path length of the detected radiation, and means for ascertaining the natural frequency of vibration of the flexible member from the variation in intensity of the detected radiation.
14. An apparatus according to claim 13 including a buffer means for temporaily storing the signal representing the output of the radiation detector.
15. An apparatus according to claim 13 or claim 14 including means for modulating the source of radiation, and means for demodulating the detected radiation.
16. An apparatus according to any of claims 13 to 15 including means for filtering the signal representing the output of the radiation detector to remove signals outside a predetermined frequency band, which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and means for measuring the frequency of the filtered signal to ascertain the actual value of the natural frequency.
17. An apparatus according to any of claims 13 to 16 in which the radiation source emits eletromagnetic radiation.
18. An apparatus according to claim 17 in which the radiation source emits visible light.
19. An apparatus according to claim 17 in which the radiation source emits infra-red radiation.
20. An apparatus according to any of claims 17 to 19, including a light guide for guiding the radiation from the source and to the detector.
21. An apparatus according to claim 20 in which an end of the light guide is bevelled to refract the incident and reflected radiation.
22. An apparatus according to any of claims 17 to 21, in which the radiation source includes a laser.
23. An apparatus according to any of claims 13 to 22, in which the radiation source is arranged to direct the radiation entirely onto the flexible member.
24. An apparatus according to any of claims 13 to 23 in which the radiation source is arranged to produce a parallel beam of radiation.
25. A drive belt system including a drive belt arranged to be driven around a plurality of pulleys and an apparatus according to any of claims 13 to 24 for monitoring the tension in the drive belt.
26. A drive belt system according to claim 25, including means for providing a warning whenever the tension in the drive belt departs from a predetermined range.
27. A motor-driven vehicle including a drive belt system according to claim 25 or claim 26.
28. A method of monitoring the tension in a vibrating elongate flexible member in which the vibrations of the flexible member are detected, the signal representing the output of the vibration detector is filtered to remove signals outside a predetermined frequency band, which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and the frequency of the filtered signal is measured to ascertain the actual value of the natural frequency.
29. An apparatus for monitoring the tension in a vibrating elongate flexible member including means for detecting the vibrations of the flexible member, means for filtering the signal representing the output of the vibration detector to remove signals outside a predetermined frequency band, which band covers the range within which the natural frequency of vibration of the flexible member is expected to lie, and means for measuring the frequency of the filtered signal to ascertain the actual value of the natural frequency.
30. A method of monitoring the tension in a vibrating elongate flexible member, the method being substantially as described herein with reference to, and as illustrated by, the accompanying drawings.
31. An apparatus for monitoring the tension in a vibrating elongate flexible member, the apparatus being substantially as described herein with reference to, and as illustrated by, the accompanying drawings.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8813630A GB2219657A (en) | 1988-06-09 | 1988-06-09 | Method and apparatus for monitoring the tension in an elongate flexible member |
| PCT/GB1989/000682 WO1990015974A1 (en) | 1988-06-09 | 1989-06-19 | Method and apparatus for monitoring the tension in an elongate flexible member |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8813630A GB2219657A (en) | 1988-06-09 | 1988-06-09 | Method and apparatus for monitoring the tension in an elongate flexible member |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8813630D0 GB8813630D0 (en) | 1988-07-13 |
| GB2219657A true GB2219657A (en) | 1989-12-13 |
Family
ID=10638334
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8813630A Withdrawn GB2219657A (en) | 1988-06-09 | 1988-06-09 | Method and apparatus for monitoring the tension in an elongate flexible member |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2219657A (en) |
| WO (1) | WO1990015974A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2249175A (en) * | 1990-10-24 | 1992-04-29 | Skf Gmbh | Determining tension in a drive belt |
| FR2705750A1 (en) * | 1993-05-28 | 1994-12-02 | Eca | Method and device for adjusting the tension of a belt |
| EP0909940A3 (en) * | 1997-10-15 | 2000-03-22 | Polar Electro Oy | Method and apparatus for measuring power output and for measuring tension and vibrational frequency of a elongate flexible member |
| NL1011625C2 (en) * | 1999-03-22 | 2000-09-27 | Skf Engineering & Res Services | A method of controlling a belt pulley drive system, as well as a belt pulley drive system. |
| GB2497100A (en) * | 2011-11-30 | 2013-06-05 | Schrader Electronics Ltd | Belt monitoring apparatus and method |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1257960B (en) * | 1992-12-30 | 1996-02-19 | Comau Spa | PROCEDURE AND DEVICE FOR THE CONTROL OF THE VOLTAGE DEGREE OF A STRETCHED ELASTIC ELEMENT, PARTICULARLY OF A DRIVE BELT |
| IT201800011168A1 (en) * | 2018-12-17 | 2020-06-17 | Magneti Marelli Spa | METHOD FOR DETERMINING THE TENSION OF A BELT OF A MOTORCYCLE TRANSMISSION UNIT BETWEEN DEVICES OF A VEHICLE |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1121254A (en) * | 1966-03-09 | 1968-07-24 | Du Pont | Tension indicator and controller apparatus |
| GB1413792A (en) * | 1971-11-23 | 1975-11-12 | Masson Scott Thrissell Eng Ltd | Methods and apparatus for measuring web tension |
| GB1587651A (en) * | 1976-03-30 | 1981-04-08 | Svenska Traeforskningsinst | Method and apparatus for measuring web tension |
| GB2082323A (en) * | 1980-08-13 | 1982-03-03 | Beloit Corp | Method and apparatus for measuring web tension of a moving web |
| GB2127544A (en) * | 1982-09-22 | 1984-04-11 | Rhone Poulenc Fibres | Measuring tension |
| GB2131643A (en) * | 1982-12-09 | 1984-06-20 | Raimo Ahola | Measuring oscillatory motion |
| WO1987005699A1 (en) * | 1986-03-12 | 1987-09-24 | James Stonehouse Burdess | Monitoring tension in an elongate flexible member |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT329902B (en) * | 1973-05-23 | 1976-06-10 | Voest Ag | METHOD FOR DETERMINING TENSION DISTRIBUTION OVER THE WIDTH OF A COLD-ROLLED STRIP AND DEVICE FOR CARRYING OUT THE METHOD |
| US4158962A (en) * | 1978-03-03 | 1979-06-26 | Paul Conoval | Cable tension measuring apparatus |
| DE2945229C2 (en) * | 1979-11-09 | 1984-02-09 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Device for non-contact vibration measurement using the laser Doppler effect |
| GB2068112B (en) * | 1980-01-24 | 1983-06-02 | Ferranti Ltd | Vibration detector |
| DE3333710A1 (en) * | 1983-09-17 | 1985-04-04 | Bayerische Motoren Werke AG, 8000 München | Use of the method for measuring the pre-tension force in a pretensioned actuating cable for setting the pre-tension force in the endless belt of a belt drive |
| DE3378990D1 (en) * | 1983-10-25 | 1989-02-23 | Ibm | An optical vibration analyser |
-
1988
- 1988-06-09 GB GB8813630A patent/GB2219657A/en not_active Withdrawn
-
1989
- 1989-06-19 WO PCT/GB1989/000682 patent/WO1990015974A1/en unknown
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1121254A (en) * | 1966-03-09 | 1968-07-24 | Du Pont | Tension indicator and controller apparatus |
| GB1413792A (en) * | 1971-11-23 | 1975-11-12 | Masson Scott Thrissell Eng Ltd | Methods and apparatus for measuring web tension |
| GB1587651A (en) * | 1976-03-30 | 1981-04-08 | Svenska Traeforskningsinst | Method and apparatus for measuring web tension |
| GB2082323A (en) * | 1980-08-13 | 1982-03-03 | Beloit Corp | Method and apparatus for measuring web tension of a moving web |
| GB2127544A (en) * | 1982-09-22 | 1984-04-11 | Rhone Poulenc Fibres | Measuring tension |
| GB2131643A (en) * | 1982-12-09 | 1984-06-20 | Raimo Ahola | Measuring oscillatory motion |
| WO1987005699A1 (en) * | 1986-03-12 | 1987-09-24 | James Stonehouse Burdess | Monitoring tension in an elongate flexible member |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2249175A (en) * | 1990-10-24 | 1992-04-29 | Skf Gmbh | Determining tension in a drive belt |
| GB2249175B (en) * | 1990-10-24 | 1994-06-01 | Skf Gmbh | A method of determining the tension in drive belts |
| FR2705750A1 (en) * | 1993-05-28 | 1994-12-02 | Eca | Method and device for adjusting the tension of a belt |
| EP0909940A3 (en) * | 1997-10-15 | 2000-03-22 | Polar Electro Oy | Method and apparatus for measuring power output and for measuring tension and vibrational frequency of a elongate flexible member |
| US6356848B1 (en) | 1997-10-15 | 2002-03-12 | Polar Electro Oy | Method and apparatus for measuring power output and for measuring tension and vibrational frequency of a elongate flexible member |
| NL1011625C2 (en) * | 1999-03-22 | 2000-09-27 | Skf Engineering & Res Services | A method of controlling a belt pulley drive system, as well as a belt pulley drive system. |
| WO2000057083A1 (en) * | 1999-03-22 | 2000-09-28 | Skf Engineering And Research Centre B.V. | Method for controlling a belt-pulley drive system, and belt-pulley drive system |
| GB2497100A (en) * | 2011-11-30 | 2013-06-05 | Schrader Electronics Ltd | Belt monitoring apparatus and method |
| WO2013079530A1 (en) * | 2011-11-30 | 2013-06-06 | Schrader Electronics Limited | Dynamic belt monitoring apparatus and method |
| GB2497100B (en) * | 2011-11-30 | 2016-05-18 | Schrader Electronics Ltd | Dynamic belt monitoring apparatus and method |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990015974A1 (en) | 1990-12-27 |
| GB8813630D0 (en) | 1988-07-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |