DE3330519A1 - Method for contactlessly transmitting a signal from a rotating component to a stationary component - Google Patents

Abstract

The invention relates to a method for contactlessly transmitting a signal from a rotating component to a stationary component, particularly of a dynamic measurement value converted into an electrical voltage by a piezoelectrical transducer from a rotating shaft to a stationary part of the bearing, through two coils inductively coupled to one another, one coil being a part of a tuned resonant circuit, the resonant frequency fR of which is detuned by the signal US to be transmitted, the other coil, as coupling coil, being a part of an evaluating coupling circuit to which an oscillator voltage Uo with constant oscillator frequency fo is applied, a tuned resonant circuit voltage UR with a tuned resonant circuit current IR being induced in the coil of the tuned resonant circuit by the inductive coupling to the coupling coil of the evaluating coupling circuit and a phase comparison being carried out for determining the magnitude of the signal US to be transmitted. To be able to transfer the signals continuously in a simple and reliable manner and without great electronic complexity, it is proposed that the oscillator voltage Uo is applied continuously to the evaluating coupling circuit and that the change in the phase shift between the coupling coil voltage UK present across the coupling coil and the coupling coil current IK in the evaluating coupling circuit due to the ... Original abstract incomplete.

Description

power supply required on the sensor side for signal amplification and transmission.

From DE-OS 31 07 947 is a method and a device for transferring a measured value from a movable object to a stationary object of the type mentioned at the beginning known. The device consists of two oscillating circuits which are inductively coupled to one another via their coils. The coupling oscillating circuit has a variable inductance or capacitance due to the signal to be transmitted, so that the resonance frequency of the coupling resonant circuit is detuned depending on the size of the measured value to be "" "" ■ to be transmitted. The other oscillating circuit is a send / receive oscillating circuit that is switched to an alternating mode with a send stage and a receive stage. That The transmission method consists in that the transmitting / receiving resonant circuit with an oscillator voltage via the transmitting stage Reference frequency is activated. Due to the inductive coupling with the coil of the coupling resonant circuit, this is accordingly the reference frequency of the transmit / receive resonant circuit induces an oscillation. After switching off the transmission level and, if necessary, steaming the Send / receive oscillating circuit, the receiving stage is activated. In this reception phase, in the send / receive oscillating circuit induces a frequency signal which continuously detuned the resonance frequency of the signal to be transmitted Coupling resonant circuit corresponds. A phase detector measures the time difference between the reference frequency during a predetermined period the oscillator voltage and the resonance frequency of the detuned oscillating circuit. By means of an evaluation circuit due to the measured time difference to the to be transmitted Signal can be inferred.

The known method has the disadvantage that a large electronic Effort is necessary to transmit the signal. The send / receive oscillating circuit must alternate as a send stage

and are activated as a receiving stage, the transmitting oscillating circuit being attenuated before the receiving stage is activated must be in order to be able to receive the oscillations induced by the coupling resonant circuit undisturbed. In addition, will the upper limit frequency of the measuring signal that can be transmitted is restricted by the discontinuous signal transmission. This is particularly then disadvantageous if signals that change rapidly over time are to be transmitted and registered.

Proceeding from this, the invention is based on the object of creating a method and a device that can be used without major electronic effort in a simple and reliable way continuously the signals from a rotating component to a stationary one Transfer component without contact.

As a solution, a method is proposed in which the oscillator _{voltage U Q is} continuously applied to the evaluation coupling circuit and in which the change in the phase shift between the coupling coil voltage U "applied to the coupling coil and the coupling coil current I _T. In the evaluation coupling circuit as a result of the detuning in the resonance frequency f _R , which is dependent on the size of the signal Ug to be transmitted, and the change in the phase shift between .the resonance circuit voltage Ü _R and the resonance c'hwingkr eis current I "and as a result of the inductive coupling of the coils continuously is measured.

The signals can be transmitted continuously due to the continuous operation of the evaluation coupling circuit. The procedure thus enables even high-frequency fluctuations in the signal to be transmitted to be recorded and sent to a recording device forward. The coupling coil of the evaluation coupling circuit forms together with the coil of the resonance circuit a continuously operated transformer. To maintain the magnetic flux in the transformer and as a result of the inductive Coupling results in a certain phase relationship between the

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Resonant circuit voltage U _R , the resonant circuit current I _R. the coupling coil voltage U "and i applied to the coupling coil

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the coupling coil current I _v . A change in the phase shift between the resonance circuit voltage U _R and the resonance circuit current I _R results in a phase shift between the coupling coil voltage U "and the coupling coil current I". However, since the phase shift between the resonance _{circuit voltage U R} and the resonance _{circuit current I R} depends on the detuning caused by the signal to be transmitted υ _σ , the measurement of the change in the phase shift between the coupling coil voltage U "and the coupling coil current I _K in the evaluation coupling circuit of the signal to be transmitted U "determine. Such a phase comparison has the advantage that it can be carried out without great electronic expenditure.

According to a further feature of the invention, to measure the phase shift between the coupling coil voltage U "and the Coupling coil current I "suggested in the evaluation coupling circuit that the values of the coupling coil voltage U "and the coupling coil current I ". measured and multiplied with each other at the same time. This method can be implemented in a technically simple manner, the analog or digital output signal being a direct statement on the size of the phase shift and thus on the size of the signal to be transmitted.

In a preferred procedure, if the oscillator frequency f _n and the resonance frequency f- are equal, the phase shift between the coupling coil insulation EL and the measuring

value of the coupling coil current I ^ set to 90 ° by a phase shifter. As a result, the direct component of the output voltage of the multiplication assumes the value zero when the resonant circuit is undununted, that is to say whenever there is no signal voltage U _3. The alternating component of the output voltage of the multiplication is suppressed by a low-pass filter.

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As soon as the signal voltage u to be transmitted detuned the resonance circuit, the phase shift at the multiplier deviates from 90 ° j and the voltage U. at the output of the low-pass filter assumes a value that is approximately linearly related to the signal voltage U. After appropriate calibration, after multiplication and low-pass filtering, the magnitude of the signal U "can be read off directly.

Finally, it is proposed with the method that the oscillator frequency f _{Q of} the evaluation coupling circuit is readjusted as a function of the measured phase shift for zero adjustment. In this way it can be achieved that the oscillator frequency f_ can be readjusted at the beginning of a new series of measurements. This is particularly advantageous if, when the resonant circuit is not tuned, i.e. when no signal U ₃ is present, the oscillator frequency f_ is to be equal to the resonance frequency f _R and the output signal U. of the measured phase shift is to be zero.

To carry out the method according to the invention, a device is proposed in which the resonance circuit is arranged on the rotating component and the evaluation coupling circuit is arranged on the stationary component, in which the coil of the resonance circuit and the coupling coil of the evaluation coupling circuit are ring-shaped and are arranged concentrically to the axis of rotation of the rotating component and that the evaluation coupling circuit is connected to an evaluation unit for measuring the coupling coil voltage U n applied to the coupling coil and the coupling coil current I _K and for determining the phase shift from the measured values obtained.

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This concentric arrangement of the coils means that the signal can be transmitted at any time regardless of the relative position of the components. The transmission is independent of the speed of the rotating component, so that a certain value of the signal U ₃ always leads to a reproducible phase shift in the evaluation coupling circuit and thus to a reproducible output signal U. It is particularly advantageous that the transmission of the signal ϋ _{σ is} flawlessly guaranteed even when the components are at a standstill.

The coils can be pushed next to one another on the axis of rotation or preferably one inside the other. As a result, the magnetic flux generated by the coupling coil of the evaluation coupling circuit completely penetrates the coil of the resonant circuit, so that an optimal signal-to-noise ratio when measuring the signal U _{3 is} possible.

A phase-shifting shunt is preferably used as a shunt in the evaluation coupling circuit Reactance switched, which can be either an inductance or a capacitance or both. With such a Phase shifter can be achieved in particular that when the oscillator frequency f ~ and the resonance frequency f the Phase shift between the coupling coil voltage Uj, and the The measured value of the coupling coil current I "is 90 °, since then that of the coil of the resonance circuit to the coupling coil of the evaluation coupling circuit transformed impedance a pure resistance represents.

In a preferred embodiment, a multiplier is provided as the evaluation unit, which multiplies the measured values of the coupling coil voltage U _K and the coupling coil current I "at the same time and converts them into an output signal U". Such a multiplier; r

works reliably and is technically not very complex, so that A transmission of the signal Ug is possible even with the simplest of measuring instruments.

According to a further feature of the invention, the multiplier is followed by a low-pass filter with a lower cut-off frequency than the oscillator frequency f ~ for smoothing. To retune the oscillator frequency f _n , a regulator controlled by the output signal U. of the multiplier can also be provided. In this way, repercussions of the demodulator circuit on the resonant circuit can be compensated.

Further details and advantages of the subject matter of the invention emerge from the following description of the associated Drawing in which a preferred embodiment for contactless Transmission of a signal from a rotating component to a stationary component has been shown. In the Drawing shows:

Pig. 1 shows a longitudinal section through a transmission device with two coils pushed into one another, the lower part being left out,

2 shows a basic circuit diagram of the demodulator circuit "and

3 shows a basic current, voltage and capacitance s-voltage characteristic of a capacitance diode.

_{The transmission device shown in Fig. 1 consists of two coils L p} , L ^ arranged concentrically to one another and to the axis of rotation 1 of a shaft. The inner coil L _R is firmly connected to the rotatable shaft 2, while the outer coupling coil

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L _{K is} fixed and is arranged on a stationary component 3 shown schematically.

To transmit a signal ü _g from the shaft 2 to the stationary component 3, the coil L _{R is} part of a resonant _{circuit S R} and the coupling coil L “is part of an evaluation coupling circuit S”. The circuit is shown in FIG. In addition to the inductance of the coil L _R , the parallel resonance circuit S _{R is} defined by the capacitance of a capacitance diode CD. The basic mode of operation of the capacitance diode CD is shown in FIG. 3, where both the capacitance (C) and the current (I) are plotted against the voltage (U). It can be seen here that the capacitance drops exponentially as the voltage increases. It can also be seen that the current initially drops very sharply, also approximately assumes the value zero in the area of voltage zero and increases very slightly when the voltage is increased (in the opposite direction of flow), and finally increases very sharply at high voltages. The control range A for changing the capacitance of a capacitance diode is determined by the current-voltage characteristic. In Fig. 3, the control range A is shown by the two dashed lines parallel to the ordinate. In this modulation range A, the power consumption is only small as a result of the low current, ie the capacitance of a capacitance diode can be changed with a small power.

The signal voltage Ug is applied to the capacitance diode CD of the resonance circuit S _R and thus changes its resonance frequency f _R and the phase shift between the resonance _{circuit voltage U R} and the resonance circuit current I _R. A bias for the varactor diode CD is not necessary as long as it is not driven into the pass band

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(steep rise in current I in Fig. 3). The dynamic range A, which is symmetrical to the voltage zero point without bias, is limited by the forward current of the diodes and the associated load on the signal voltage source as well as by the permissible non-linear distortion of the transmission. A diode Dl is used to balance the load on the signal voltage source. By connecting a capacitor C in parallel in the resonant circuit S _{R, it} can be tuned to the desired resonant frequency f _R ; however, the linearity and sensitivity of the arrangement change at the same time.

With a modulation range of around 100 mVss, the transmission device for almost all available electrodynamic and piezoelectric transducers. As a result of the high

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Input impedance (in the order 10 'Ohm _s 100 pF) is practically not charged to the converter.

A change in the resonance frequency f _R is also conceivable if the inductance of the coil L _{R is} changed by the signal Uo.

The continuous evaluation of the detuning of the rotating resonance _{circuit S R, which is dependent on the signal U g,} is carried out by means of the evaluation coupling circuit S ", which evaluates the variable resonance frequency f _R or the phase shift between the resonance _{circuit voltage U R} and the resonance circuit current I" using an oscillator signal of constant frequency. The basic circuit of the evaluation coupling circuit S ″ is shown in FIG. 2 on the right-hand side.

The evaluation coupling circuit Sg- consists of the coupling coil Lg- and is operated with an oscillator _{voltage U Q} with a constant oscillator frequency f _Q from a voltage-controlled oscillator VcO (Voltage Controlled Oscillator), the oscillator frequency f "

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equal to the time average of the resonance frequency f "of the ro-

animal resonance circuit f_ is. A reactance X (inductance or capacitance) serving as a shunt and phase shifter is connected to the evaluation coupling circuit S ". The coupling coil voltage tL · is tapped at the coupling coil L "of the evaluation coupling circuit S" and fed together with the coupling coil current I "measured via the shunt X to an evaluation unit 4, which is designed as a multiplier. The output signal U. of the multiplier passes through a low-pass filter 5, the cutoff frequency of which is lower than the oscillator frequency f _n . As will be explained in more detail below, the phase shift between the coupling coil _{voltage U K} and the measured value of the coupling coil current I "is decisive for the measurement process, so that for the measurement and phase shift of the coupling coil current I" the voltage applied to the reactance X is measured and the evaluation unit 4 is fed.

The two coils L _R and L "form a transformer T ₃ , the inductive coupling through the mutual inductance M being shown symbolically in the drawing. By using the oscillator voltage U "with a constant oscillator frequency f" driven Auswertekoppelkreis S "a Resonanζschwingkreisspannung U _R with a Resonanzschw-ingkreisstrom I _R is induced in the resonant circuit S _R, where the resonance frequency f_ equal to the oscillator frequency f _0. The inductive coupling of the two coils L "and L _R creates a fixed phase relationship to maintain the magnetic flux: between the coupling coil voltage U ^, the coupling coil current I", the resonant circuit voltage U "and the resonant circuit current I". When the capacitance of the capacitance diode CD changes due to the signal U ", the resonance frequency f ^ of the resonance circuit S _{n changes} and thus also

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the phase shift between the resonant circuit voltage U _n and the resonant _{circuit current I n} , which has the consequence that the phase shift between the coupling coil voltage U _K and the coupling coil current I "changes. This change in the phase shift between the coupling coil voltage U "and the coupling coil current I" also changes the output signal U. of the evaluation unit 4.

As long as the resonance frequency f _{n of} the resonance _{circuit S n is} equal to the oscillator frequency f _Q , the phase shift between the resonance circuit voltage IL and the

Resonant _{circuit current I n} zero degrees and the after the coupling

coil L _T , transformed impedance represents a pure resistance. The phase shift between the coupling coil voltage Ut and the measured value of the coupling coil current I "is due to the reactance X 90 °, so that the output signal U. at the low-pass filter 5 is zero" volts Detuning the resonance circuit S _n by a signal U _Q influences the phase shift between the coupling coil voltage U "and the coupling coil current I _K and thus the output signal U .. Between the detuning of the rotating resonance circuit S _n and the output signal U. there is an approximately linear one Relationship, so that the value of the signal U _g to be transmitted is determined by the value of the output signal U.

To avoid repercussions of the demodulator circuit of the evaluation coupling circuit Sy. To equalize the resonance _{circuit S R} from ₃ , an automatic zero adjustment is provided by the output signal U. via a suitable controller 6, the oscillator frequency

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f _{Q of} the voltage controlled oscillator VCO readjusts. _{This can be done by changing the oscillator frequency f Q} for a signal U "of zero volts until it corresponds to the resonance frequency f _n and there is no output signal ü,

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is present. The dimensioning of the controller 6 has an influence on the lower limit frequency of the transmission path, because low-frequency fluctuations in the resonance frequency f _{R of} the resonance _{circuit S R are} regulated. If static signal components are also to be transmitted, the control voltage U _R is to be tapped off at the output of the controller 6 as the signal voltage. In this case, the controller β largely determines the upper limit frequency of the signal voltage.

- - 4 $ "" List of reference symbols 1 Axis of rotation 2 while 3 fixed component 4th Evaluation unit '5 Low pass filter 6th Regulator ^S R Resonance circuit ^L R Kitchen sink CD Capacitance diode Dl diode C. capacitor ⁸ K Evaluation coupling circuit ^L K Coupling coil X Reactance vco voltage controlled oscillator T transformer A. Dynamic range ^U O Oscillator voltage ^f o Oscillator frequency ^U K Coupling coil voltage ¹ K Coupling coil current ^U R Resonant circuit voltage ¹ row Resonant circuit current ^f R Resonance frequency ^U S signal ^U A Output signal ^U Reg Reg ^ control voltage M. Geg, enindukt ivit ät

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Claims (12)

·. - PATENTANWÄLTE -j. · ":> R *: ::" *: -: * ": pi * pl-ing. Alex steng er Kaiser-Friedrich-Ring 70 CilTPL.-ING. WOLFRAM WATZKE D-4000 DÜSSELDORF 11 3OQHRIQ DIPL.-ING.HEINZ J. RING EUROPEAN PATENT ATTORNEYS Our reference: 24 420 Date: 23- August 1983 Prof. Dr.-Ing.Manfred Weck, Im Weingarten 16, 5100 Aachen Patent claims: 1. A method for the contactless transmission of a signal from a rotating component to a stationary component, in particular a dynamic measured value from a rotating shaft to a stationary part of the bearing, which is converted into an electrical voltage by a piezo-electric converter, by means of two inductively coupled coils, One coil is part of a resonance _{circuit, the resonance frequency f R} of which is detuned by the signal U ₃ to be transmitted, and the other coil, as a coupling coil, is part of an evaluation coupling circuit to which an _{oscillator voltage U Q} with a constant oscillator frequency fQ is applied, with in _{A resonance circuit voltage U R} with a resonance _{circuit current I R is} induced in the coil of the resonance circuit by the inductive coupling with the coupling coil of the evaluation coupling circuit, and a phase comparison is carried out to determine the size of the signal U _{g to be transmitted,}
characterized in that the oscillator _{voltage U Q is} continuously applied to the evaluation coupling circuit and that the change in the phase shift between the coupling coil voltage U "applied to the coupling coil and the coupling coil _{current I K} in the evaluation coupling circuit due to the detuning in the resonance frequency f _R and the change in the phase shift between the resonance circuit voltage U _R and the resonance circuit current I _R and is measured continuously as a result of the inductive coupling of the coils. Telephone (0211) 57 2131 Telex: 85 88429 pate d Telegram address: Rheinpatent Postal check account Cologne (BLZ 370100 SO) 227610 - 503 • * Ur V. * 2. The method according to claim I _3, characterized in that to measure the phase shift between the coupling coil voltage U _K and the coupling coil current I ~ in the evaluation coupling circuit, the values of the coupling coil voltage U "and the coupling coil current I are measured simultaneously and multiplied with one another. 3. The method according to claim '1 or 2, characterized in that if the oscillator frequency f_ and the resonance frequency f are the same, the phase shift between the measured values of the coupling ri coil voltage ü "and the coupling coil current I _T , is set to 90 °. 4. The method according to any one of claims 1 to 3, characterized in that the evaluation coupling circuit with an oscillator frequency f _n , which is equal to the resonance frequency f _{D of} the inconsistent resonance υ κ Oscillating circuit is operated. 5. The method according to any one of claims 1 to 3j, characterized in that the evaluation coupling circuit is operated with an oscillator frequency f_ ₃ which is equal to the resonance frequency f_ on average over time. 6. The method according to any one of claims 1 to 5 _S, characterized in that for zero adjustment, the oscillator frequency f_ of the evaluation coupling circuit is readjusted as a function of the measured phase shift. 7. Device for performing the method according to one of the claims 1 to 6, the resonance circuit on the rotating Bciateii and the evaluation coupling circuit on the stationary component is arranged characterized in that the coil (L _R ) of the resonant circuit (S _R ) and the 3330513 Coupling coil (L _K ) of the evaluation coupling circuit (S ") is ring-shaped and arranged concentrically to the axis of rotation (1) of the rotating component (2) and that the evaluation coupling circuit (S ^) is connected to an evaluation unit (4) for measuring the values at the coupling coil ( L ") applied coupling coil voltage U" and the coupling coil current Ty. and connected from the obtained measured values for determining the phase shift is _o t. 8. Apparatus according to claim 7 »characterized in that the coils (L _R , L") are pushed into one another. 9. Apparatus according to claim 7 * characterized in that the coils (L _R , '.
are arranged. Bobbins (L _R , L ") next to each other on the axis of rotation (1) 10. Device according to one of claims 7 to 9 » characterized in that a reactance (X) (inductance and / or capacitance) is connected as a shunt and phase shifter in the evaluation coupling circuit (S ^). 11. Device according to one of claims 7 to 10, characterized in that a multiplier is provided as the evaluation unit (4) which simultaneously multiplies the measured values of the coupling coil voltage U "and the coupling coil current I" and converts them _{into an output signal U fl.} 12. The device according to claim 11, characterized in that the multiplier is followed by a low-pass filter (5) with a lower cut-off frequency than the oscillator frequency f _ß for smoothing. 13- device according to claim 11 or 12, characterized in, that a controller (6) controlled by the output signal U. of the multiplier for retuning the oscillator frequency f ^ is provided. W / Gy / dg "- -: -; - -:. :; : ■; . -DIPL.-ING. ALU bltNOtK Kaiser-Friedrich-Ring 70 * "*" .// *. ',,. V- h__ \ r '_ " DIPL.-ING. WOLFRAM WATZKE D-4000 DÜSSELDORF 11 \ £ _Ä g QO Q g ¹¹ JQ * DIPL.-ING. HEINZ J. RING ^ "\ EUROPEAN PATENT ATTORNEYS EUROPEAN PATENT ATTORNEYS Our mark: ο Ii lion Date: _n ² ^ 420: August 23, 1983 Prof. Dr.-Ing. Manfred Weck, Im Weingarten 16, 5100 Aachen Method for the contactless transmission of a signal from a rotating component to a stationary component The invention relates to a method for the contactless transmission of a signal from a rotating component to a stationary component, in particular a dynamic measured value converted into an electrical voltage by a piezoelectric transducer from a rotating shaft to a stationary part of the bearing, by means of two inductively coupled coils, One coil is part of a resonance _{circuit, the resonance frequency f R} of which is detuned by the signal U _g to be transmitted, and the other coil, as a coupling coil, is part of an evaluation coupling circuit to which an oscillator _{voltage U 0} with a constant oscillator frequency f _{Q is} applied, with _{A resonance circuit voltage U R} with a resonance circuit current I "is induced in the coil of the resonance circuit by the inductive coupling with the coupling coil of the evaluation coupling circuit, and a phase comparison is carried out to determine the size of the signal Ug to be transmitted will be carried out, as well as a device for carrying out the process. Telemetry devices for transmitting measured values from rotating parts to stationary parts are known. For example, you play in the air pressure monitoring of a vehicle wheel, where the air pressure value of the wheel rotating while driving is on an im The vehicle chassis for monitoring and, if necessary, for regulating the air pressure is to be transferred, However, known methods and devices have the disadvantage of _ 2 Telticn w- Ii) 57 2131 · Telex: 85 88429 pate d ■ Telegram address: Rheinpatent · Postal check account Cologne (BLZ 370100 SO) 227610- 503