EP0041856A1 - Telemetry apparatus - Google Patents
Telemetry apparatus Download PDFInfo
- Publication number
- EP0041856A1 EP0041856A1 EP81302527A EP81302527A EP0041856A1 EP 0041856 A1 EP0041856 A1 EP 0041856A1 EP 81302527 A EP81302527 A EP 81302527A EP 81302527 A EP81302527 A EP 81302527A EP 0041856 A1 EP0041856 A1 EP 0041856A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- voltage
- strain
- frequency
- converter
- shaft
- 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- Withdrawn
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Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
- G08C17/06—Arrangements for transmitting signals characterised by the use of a wireless electrical link using capacity coupling
Definitions
- This invention relates to telemetry apparatus comprising a strain gauge mounted on a first of two parts and providing an alternating signal to a detector circuit 4 nounted on the second part by way of a capacitive coupling between the two parts.
- a conventional method to collect strain data from a vehicle drive shaft under operating conditions is to mount a bridge circuit, of which one element is the strain gauge, strategically on the shaft.
- the problem then exists of transferring the data from the rotating shaft, i.e. the aforementioned first part, to the body of the vehicle, i.e. the second part.
- One solution e.g. US-PS 3 824 845) is to use slip rings but slip rings are a source of trouble in that the electrical connection provided thereby tends to deteriorate.
- the strain gauge circuit is energised by an alternating signal from an oscillator mounted on the second part and capacitatively coupled to the strain gauge circuit on the first part.
- Such an arrangement requires two capacitive couplings, each involving two capacitors, to couple the energising alternating signal to the strain gauge circuit and to couple the output alternating signal to the detector circuit.
- Four capacitors in all are thus required, each with one plate on the first part and one plate on the second shaft. This makes the apparatus complicated.
- An arragement is also known CUS-PS 3 303 701) which requires only two coupling capacitors for the case of a temperature measurement, employing a resonant circuit on the first part.
- the frequency of the resonant circuit varies in dependence upon a temperature sensitive element therein and the resonant circuit is coupled by the capacitors to an amplifier circuit on the second part to form an oscillator whose frequency indicates the temperature.
- the relationship between frequency and temperature is nonlinear.
- the object of this invention is to provided an apparatus according to the introductory part of claim 1 which only requires two coupling capacitors but which can provide a linear representation of the measured strain and this object is met by the characterising features according to which the strain gauge circuit includes a voltage to frequency converter providing the alternating signal in response to a voltage proportional to the strain.
- a bridge network is secured on a part subjected to strain, such as a shaft.
- the output from the bridge network which is proportional to element strain, is delivered to a voltage to frequency converter.
- the output from the frequency converter is in the form of a square wave with a frequency proportional to the strain.
- the output from the frequency converter is delivered to a first set of capacitance rings placed about the part for which strain readings are desired.
- a second set of stationary capacitance rings placed around the first rings provide capacitive coupling utilizing air as the dielectric.
- the received signal is in the form of a differentiated square wave and is delivered to a squaring amplifier and thereafter to a frequency to voltage converter, wherefrom the signal is delivered by a readout device.
- a voltage source shown as a battery supplies a voltage to an adjustable voltage regulator 11 of conventional design which delivers a voltage to a bridge network 13.
- the bridge network 13 is strategically located on the vehicle drive shaft (not shown) in a conventional manner and includes as one resistor thereof a strain gauge.
- the bridge produces an output voltage drop across the bridge network 13 proportional to shaft strain.
- the output from the bridge network 13 is delivered to a voltage to frequency converter 15, such as manufactured by Analog Devices, Model AD537.
- the output from the voltage to frequency converter 15 is in the form of a square wave having frequency proportional to shaft strain (illustratively shown in Fig 2).
- the output from the frequency converter 15 is delivered to a capacitive coupling system 17.
- the capacitive coupling system 17 includes first and second capacitance rings 19 and 21.secured around the periphery of the shaft in a conventional manner. All of items 11, 13, 15, 19 and 21 are mounted on the shaft. Third and fourth capacitance rings 23 and 25 are fixed in close proximity to the associated rings 19 and 21 respectively.
- the frequency modulated voltage across rings 19 and 21 as received from the voltage to frequency converter 15 is transmitted to rings 23 and 25 using air as a dielectric.
- the signal output from rings 23 and 25 is in the general form of a differentiated square wave (Fig 3).
- the signal from rings 23 and 25 can then be delivered to an input amplifier 27 to increase its level.
- the signal can be processed.further by passing it to a squaring amplifier 29, frequency to voltage converter 31 and then to a recorder or direct readout device 33. All of items 23, 25, 27, 29, 31 and 33 are mounted on the vehicle body.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
- Testing Of Balance (AREA)
Abstract
The output from a strain gauge bridge 13 on a shaft is transmittedtoafixeddetector27,29,31 using only twocoupl- ing capacitors 19, 23, and 21,25, each with a rotating plate 19 or 21 and a fixed plate 23 or 25, by applying the voltage from the bridge to a voltage to frequency converter 15 also mounted on the shaft. The converter 15 provides a square wave signal with frequency proportional to strain. This is received by the detector circuit as a differentiated square wave. A squaring amplifier 29 and frequency to voltage converter 31 reconstitute a voltage proportional to strain.
Description
- This invention relates to telemetry apparatus comprising a strain gauge mounted on a first of two parts and providing an alternating signal to a detector circuit 4nounted on the second part by way of a capacitive coupling between the two parts.
- It is often necessary in evaluating the dynamics of a system to collect strain data. For example, one may wish to obtain torque and bending strain data from a vehicle drive shaft. A conventional method to collect strain data from a vehicle drive shaft under operating conditions is to mount a bridge circuit, of which one element is the strain gauge, strategically on the shaft. The problem then exists of transferring the data from the rotating shaft, i.e. the aforementioned first part, to the body of the vehicle, i.e. the second part. One solution (e.g. US-PS 3 824 845) is to use slip rings but slip rings are a source of trouble in that the electrical connection provided thereby tends to deteriorate. Another solution (US-PS 3 668 673) applies the output from the strain gauge bridge to a sub-carrier oscillator (SCO) whose deviation from its centre frequency is proportional to the strain imposed on the strain bridge. The output from the SC0 is used to modulate a radio frequency oscillator (RFO) whose output is transmitted to a receiver. The use of a radio frequency signal can create disturbance to other vehicle electrical components. Also, the transmitted radio frequency can be reflected off metal vehicle components to create noise problems in the received signal.
- In another solution, which is in accordance with the introductory part of claim 1, (US-PS 3 224 257) the strain gauge circuit is energised by an alternating signal from an oscillator mounted on the second part and capacitatively coupled to the strain gauge circuit on the first part. Such an arrangement requires two capacitive couplings, each involving two capacitors, to couple the energising alternating signal to the strain gauge circuit and to couple the output alternating signal to the detector circuit. Four capacitors in all are thus required, each with one plate on the first part and one plate on the second shaft. This makes the apparatus complicated.
- An arragement is also known CUS-PS 3 303 701) which requires only two coupling capacitors for the case of a temperature measurement, employing a resonant circuit on the first part. The frequency of the resonant circuit varies in dependence upon a temperature sensitive element therein and the resonant circuit is coupled by the capacitors to an amplifier circuit on the second part to form an oscillator whose frequency indicates the temperature. However the relationship between frequency and temperature is nonlinear.
- The object of this invention is to provided an apparatus according to the introductory part of claim 1 which only requires two coupling capacitors but which can provide a linear representation of the measured strain and this object is met by the characterising features according to which the strain gauge circuit includes a voltage to frequency converter providing the alternating signal in response to a voltage proportional to the strain.
- In the preferred practice of the invention, a bridge network is secured on a part subjected to strain, such as a shaft. The output from the bridge network, which is proportional to element strain, is delivered to a voltage to frequency converter. The output from the frequency converter is in the form of a square wave with a frequency proportional to the strain. The output from the frequency converter is delivered to a first set of capacitance rings placed about the part for which strain readings are desired. A second set of stationary capacitance rings placed around the first rings provide capacitive coupling utilizing air as the dielectric. The received signal is in the form of a differentiated square wave and is delivered to a squaring amplifier and thereafter to a frequency to voltage converter, wherefrom the signal is delivered by a readout device.
- The invention will be described in more detail, by way of example, with reference to the accompanying drawings in which:
- Fig 1 is a block diagram of a telemetry apparatus embodying the invention,
- Fig 2 is a diagram of a square wave having a frequency proportional to element strain,
- Fig 3 is a diagram of a differentiated square wave having a frequency proportional to strain.
- Referring to Fig 1, a voltage source shown as a battery supplies a voltage to an adjustable voltage regulator 11 of conventional design which delivers a voltage to a
bridge network 13. Thebridge network 13 is strategically located on the vehicle drive shaft (not shown) in a conventional manner and includes as one resistor thereof a strain gauge. The bridge produces an output voltage drop across thebridge network 13 proportional to shaft strain. The output from thebridge network 13 is delivered to a voltage tofrequency converter 15, such as manufactured by Analog Devices, Model AD537. The output from the voltage tofrequency converter 15 is in the form of a square wave having frequency proportional to shaft strain (illustratively shown in Fig 2). The output from thefrequency converter 15 is delivered to acapacitive coupling system 17. - The
capacitive coupling system 17 includes first andsecond capacitance rings 19 and 21.secured around the periphery of the shaft in a conventional manner. All ofitems fourth capacitance rings rings rings frequency converter 15 is transmitted torings rings rings input amplifier 27 to increase its level. The signal can be processed.further by passing it to asquaring amplifier 29, frequency tovoltage converter 31 and then to a recorder ordirect readout device 33. All ofitems
Claims (2)
1. Telemetry apparatus comprising a strain gauge circuit mounted on a first of two parts and providing an alternating signal to a detector circuit mounted on the. second part by way of a capacitive coupling between the two parts, characterised in that the strain gauge circuit (11, 13, 15) includes a voltage to frequency converter (15) providing the alternating signal in response to a voltage proportional to the strain.
2. Telemetry apparatus according to claim 1, characterised in that the detector circuit (27, 29, 31) includes a frequency to voltage converter (31) which converts the altenating signal back to a voltage proportional to the strain.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15809280A | 1980-06-10 | 1980-06-10 | |
US158092 | 1980-06-10 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0041856A1 true EP0041856A1 (en) | 1981-12-16 |
Family
ID=22566647
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP81302527A Withdrawn EP0041856A1 (en) | 1980-06-10 | 1981-06-08 | Telemetry apparatus |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0041856A1 (en) |
ES (1) | ES8301024A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0298891A2 (en) * | 1987-07-06 | 1989-01-11 | United Technologies Corporation | Pitch control capacitance coupling |
AT388061B (en) * | 1987-03-02 | 1989-04-25 | Siemens Ag Oesterreich | SIGNAL TRANSFER SYSTEM |
GB2381075A (en) * | 2001-09-12 | 2003-04-23 | Halil Giray Hassan | Non-contact data transmission in rotating machinery |
DE102019007229A1 (en) * | 2019-10-17 | 2021-04-22 | Krebs & Aulich Gmbh | Arrangement for contactless energy and signal transmission on a rotor shaft of an electric machine |
-
1981
- 1981-06-08 EP EP81302527A patent/EP0041856A1/en not_active Withdrawn
- 1981-06-09 ES ES502872A patent/ES8301024A1/en not_active Expired
Non-Patent Citations (1)
Title |
---|
Instrument Practice, Vol. 23, No. 5, May 1969 London (GB) "Short-Range Telemetry" page 369 * the whole article * * |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT388061B (en) * | 1987-03-02 | 1989-04-25 | Siemens Ag Oesterreich | SIGNAL TRANSFER SYSTEM |
EP0298891A2 (en) * | 1987-07-06 | 1989-01-11 | United Technologies Corporation | Pitch control capacitance coupling |
EP0298891A3 (en) * | 1987-07-06 | 1990-09-12 | United Technologies Corporation | Pitch control capacitance coupling |
GB2381075A (en) * | 2001-09-12 | 2003-04-23 | Halil Giray Hassan | Non-contact data transmission in rotating machinery |
GB2381075B (en) * | 2001-09-12 | 2004-09-01 | Halil Giray Hassan | A contact-less data transmission system for rotating machinery |
DE102019007229A1 (en) * | 2019-10-17 | 2021-04-22 | Krebs & Aulich Gmbh | Arrangement for contactless energy and signal transmission on a rotor shaft of an electric machine |
Also Published As
Publication number | Publication date |
---|---|
ES502872A0 (en) | 1982-04-01 |
ES8301024A1 (en) | 1982-04-01 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): AT DE FR |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19821016 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: WAGNER, ROBERT JOHN |