JPH0318234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a transmitting stage and a receiving stage for transmitting frequency signals, the transmitting stage and the receiving stage are connectable to at least a transmitting/receiving vibration circuit, and are attached to a moving object. It has a coupled oscillating circuit that can be controlled by measured values, and a frequency signal can be supplied to the receiving stage via the coupled oscillating circuit. from a moving object to a stationary object that is fixed relative to the moving object, for example from the wheels of a motor vehicle, with a device for activating the damping means of the transmitting/receiving vibration circuit. The present invention relates to a device for transmitting measured values to a chassis.

In the case of such known devices, the coupled oscillating circuit belongs to a so-called transponder, which in addition, in the case of wheel pressure monitoring, has a switch that opens and closes depending on the pressure value, and thus the coupled oscillating circuit. be left relatively undamped or effectively shorted. As a result, a portion of the device attached to the chassis of the vehicle can detect whether the air pressure has fallen below a predetermined value. To this end, when the coupled oscillating circuit is in the vicinity of the transmitting/receiving oscillating circuit, the transmitting stage is first operatively connected so that the frequency signal received by the coupled oscillating circuit is transmitted via the transmitting/receiving oscillating circuit. be done. The energy of the frequency signal, which is magnetically coupled through the coil of the coupled oscillating circuit, excites the coupled oscillating circuit to oscillate at its natural frequency when the switch is open. When the switch is closed, the coupled oscillating circuit does not oscillate. The transmitting/receiving oscillating circuit is then damped by the control device, so that after the transmitting stage has been switched off, the vibrations occurring in the transmitting/receiving oscillating circuit are further damped rapidly. The transmitting/receiving oscillating circuit is then operatively connected to the receiving stage, also by means of the control device. If the transponder switch is opened and thus a gradually damping oscillation occurs in the coupled oscillating circuit, then during the receive phase, when the transmitting/receiving oscillating circuit is close to the coupled oscillating circuit,
The frequency signal of the transponder is received by the transmit/receive vibration circuit, whereas in this reception phase, if the switch is closed, no signal is received by the transmit/receive vibration circuit. For evaluation of the received frequency signal, an electronic counter may be provided in the receiving stage. A modified counting pulse is then supplied to the counting input of the electronic counter during a predetermined time interval formed from the received frequency signal. Therefore, when the counter value reaches a predetermined number of counts during the time interval, if the transponder switch is open and the transponder switch is closed, no count pulses are supplied to the counter and the value becomes too low. It shows that the pressure is indicated on the indicator stage.

The disadvantage of such devices is that only two separate values of the measured value are transmitted contactlessly, depending on whether the switch of the transponder is opened or closed depending on the measured value. .

Further, a transmitting stage for transmitting two transmitting signals of different frequencies, at least one coupling element fixed to the moving object for mixing the two frequencies, and a receiving stage responsive to the mixed frequency is provided. Devices are known for transmitting at least one measurement value to an object that is fixed relative to the moving body. The coupling element for mixing both frequencies is constituted by at least one oscillating circuit containing elements with a non-linear current-voltage characteristic curve. For this purpose, a diode or a transistor whose base-collector section is short-circuited can be provided.
When the coupling element switch is open, the coupling element does not transmit a frequency signal. However, when the switch is closed, the coupling element generates a signal with a frequency that corresponds to the difference between the different frequencies of the transmitted signals. A frequency signal with a difference frequency is detected in the receiving stage and evaluated for activation of the alarm indicator. If two coupling elements are used per wheel tire, for example for the transmission of temperature-dependent and pressure-dependent signals, the phase of the received signal is formed in the central device in addition to the central device having a transmitting stage and a receiving stage. phase of a reference signal of the same frequency, as well as a separate alarm indicating device. However, even in the case of phase comparison in a central device using two coupling elements, only two measured values of both measured quantities are detected and differentiated.

The object of the invention is to configure a device of the type mentioned at the outset in such a way as to enable continuous detection of measurement values transmitted from a moving object to an object that is fixed relative to the moving object. It's about doing.

According to the invention, this problem is solved in that at least one element determining the natural frequency of the coupled oscillatory circuit can be changed continuously depending on the measured value, the receiving stage has a phase detector, and the transmitting device That is, during the transmit phase, the transmitting stage sends said frequency signal to the transmitting/receiving oscillating circuit, whereby the transmitting/receiving oscillating circuit excites the coupled oscillating circuit and subsequently During the decay phase, the feed/
The vibrations in the receiving oscillating circuit are damped, and only during the next receiving phase a frequency signal corresponding to the natural frequency of the coupled oscillating circuit and continuously varied and adjusted by the measured value is transmitted/receiving vibration from the coupled oscillating circuit. This is solved by configuring the circuit to be induced.

According to this device, the measured values of the quantity to be measured are continuously detected, transmitted contactlessly and evaluated in a central device having a transmitting stage and a receiving stage. The advantage of this device is that the coupled vibratory circuit is constructed as a component of the transponder, the coil of the coupled vibratory circuit being used as a coupling element, and the quantity to be measured being determined by the change in at least one element of the coupled vibratory circuit. It has a continuous measurement value converter.

A coil or an inductance that varies depending on the measured value can be used as a measured value transducer in the coupled resonant circuit. Capacitors whose capacitance varies depending on the measured value are also effective. In either case, as the measured value changes, the coupled resonant circuit maintains a high Q due to the good transmission properties of the coupled resonant circuit. The transmission of the measured value presupposes at least a minimal coupling between the coil of the coupled oscillating circuit and the coil of the transmitting/receiving oscillating circuit, which coupling is essentially determined by the spacing of the two coils.

In the central unit, the transmit/receive oscillating circuit is used as an antenna during the transmit phase and the reference frequency is supplied as a frequency signal. The frequency of this frequency signal preferably corresponds to the resonant frequency of the transmitting/receiving oscillating circuit. During the transmission phase, vibrations are excited in the coupled oscillatory circuit, which are likewise equal in frequency to the reference frequency and are only out of phase with respect to the transmission frequency signal. At the end of the transmission phase, oscillations occur that are coupled to the coupled oscillatory circuit, which form a frequency signal that gradually decays with a frequency equal to the natural frequency of the coupled oscillatory circuit. This progressively damping oscillation also has a predetermined phase that depends on the resonant frequency of the coupled oscillating circuit with respect to the reference frequency initially transmitted as a frequency signal. Therefore, when the coupled oscillating circuit is near the transmitting/receiving oscillating circuit, the oscillations in the coupled oscillating circuit have the same frequency as the progressively damped oscillations in the coupled oscillating circuit, and a frequency that is out of phase with respect to this oscillation. induce a signal. If the transmitting/receiving vibration circuit is common to both the transmitting stage and the receiving stage,
In order to quickly switch from the transmit phase to the receive phase, between the transmit phase and the receive phase,
It is advantageous to damp the transmitting/receiving oscillating circuit so that each oscillation in the transmitting/receiving oscillating circuit is damped in a short period of time. During the reception phase, the vibrations induced in the transmitter/receiver vibration circuit are preferably amplified in a central device and evaluated with a phase detector. This phase measurement is particularly advantageous with regard to the state of motion of the coupled oscillating circuit relative to the transmitting/receiving oscillating circuit if it is carried out during small oscillations of the damping oscillations. The phase measurement is also preferably carried out as a time measurement.

Instead of measuring the phase of the frequency signal emitted by the coupled oscillating circuit coupled to the transmitting/receiving oscillating circuit during the receiving phase, the frequency measuring instrument is configured to make frequency measurements during small oscillations. Sometimes a frequency measuring device may be used.

Both the measurement of gradually damped vibrations in coupled oscillatory circuits by phase measurement and the measurement of vibrations by frequency measurement.
It has the advantage that the measurement result is not substantially influenced by the Q of the coupled resonant circuit, which may depend on the installation conditions on the measuring object, for example in the vicinity of metal parts.

In an advantageous embodiment as claimed in claim 4, the central device has an amplitude monitoring device which activates the evaluation circuit of the frequency signal in the receiving stage only if the amplitude of the frequency signal exceeds a predetermined value. Therefore, even if the coupled vibration circuit is too far away from the transmitting/receiving vibration circuit, incorrect evaluation will not occur.
More reliable detection of the phase state or frequency of the received frequency signal becomes possible. Be that as it may, the frequency signal reflected from the coupled oscillating circuit also increases in the fixed transmitting/receiving oscillating circuit during the build-up oscillation process of this transmitting/receiving circuit, and then as a result of the vibration of the coupled oscillating circuit. inducing exponentially damping vibrations. As a result, there are short time intervals in the receive phase during which the receive frequency signal has a maximum amplitude. During this time interval over one cycle, the sensitivity and measurement accuracy of the device is at its maximum.

An advantageous embodiment of a device for evaluating a received frequency signal, which outputs continuous measured values, is described in claim 5. A phase detector is used in the receiving stage to detect the zero point crossing of the reference frequency during a predetermined period of the reference frequency, and to detect the subsequent zero point passing of the frequency signal received by the receiving stage and induced by the vibration in the coupled oscillating circuit. In between, there is a device for measuring time differences. This measurement is preferably carried out during one period of the received frequency signal. In this case, it is advantageous to be able to measure independently of additional, external time or frequency signals. Rather, all the time signals can be derived by one oscillator via a frequency divider in a central device.

As mentioned above, an advantageous embodiment of the evaluation circuit arrangement for the evaluation of the obtained time differences is specified in claim 6. Here, it is preferable to provide a simple resistance-capacitor combination to which a constant current is supplied as a voltage integrator.

Another embodiment of the device is a phase detector that measures the time difference between the zero crossing of a reference frequency and the zero crossing of a received frequency signal over a plurality of periods, but overall over a relatively short time. have.

Next, the present invention will be explained in detail using illustrated embodiments.

The coupled vibration circuit of the transponder 1 in FIG.
It has a coil 2 and a capacitor 3. By configuring a coil or a capacitor as the measuring transducer, the resonant frequency of the transponder can be adjusted continuously as a function of the quantity to be measured. The transponder is fixed to a moving part, for example a vehicle wheel.

In the region of movement of the transponder, a transmitting/receiving vibration circuit 4 consisting of a coil 5 and a capacitor 6 is mounted on a fixed part. The transmit/receive oscillating circuit is excited with a frequency signal from the transmit stage 7 or sends a receive frequency signal to the receive stage 8.

Both the transmitting stage and the receiving stage belong to a central device that includes a reference frequency oscillator 9 and a control device 10 .

Both the control device 10 and the phase detectors 11 of the transmitting stage 7 and the receiving stage 8 are supplied with the oscillation frequency from the oscillator 9. The output side of the phase detector 11 of the receiving stage is connected to an evaluation circuit 12 .

A control signal is supplied from a control device to the transmitting stage, the damping stage 13 for damping the transmitting/receiving vibration circuit 4, and the phase detector 11. Similarly, a control signal is supplied from the control device 10 to the amplitude monitoring circuit 14 . This circuit 14 is also supplied with power from the transmit/receive vibration circuit and sends control signals to the evaluation circuit 12.

This circuit arrangement is such that during the transmission phase, the transmitting stage amplifies the reference frequency of the oscillator 9 and sends it to the transmitting/receiving oscillating circuit 4, and based on that, when the transponder is in the vicinity of the transmitting/receiving oscillating circuit, /The receiving vibration circuit 4 operates to excite the transponder 1. Following this, during the decay phase, the feed/
The vibrations in the receiving vibration circuit are gradually attenuated. If the transponder is located in the vicinity of the transmitting/receiving oscillating circuit, then during the next receiving phase the frequency corresponds to the natural frequency of the coupled oscillating circuit consisting of coil 2 and capacitor 3, which is continuously adjusted in accordance with the measured value. The transponder induces a frequency signal into the transmitting/receiving vibration circuit 4.

In the receiving stage, measurement is performed by enabling the phase detector to operate in response to a control signal "phase measurement operation" sent by the control device 10. The phase detector measures, during a predetermined period of time, the time difference between the next edge of the reference frequency, such as a zero crossing, and the corresponding edge of the received frequency signal. When the amplitude monitoring device 14 signals that the amplitude of the received frequency signal is sufficient for the measurement, this time signal is converted into an analog voltage in the evaluation circuit 12. Conversion of the time difference into an analog voltage can be performed by charging the capacitor of the resistive capacitor arrangement with a constant current. The capacitor voltage is then fed through the detection circuit.

According to this measurement method, one phase is called transmission phase - decay phase - reception phase (clock period).
One measurement can be taken during the course of a cycle.

The detected time difference of zero point crossing during a predetermined Nth period (reference frequency) has the following magnitude.

(ΔT) _N = N (1/f _r −1/f _k ) + φ1/2πf _k where (ΔT) _N is the time difference between the zero point passing of the reference frequency f _r and the zero point passing of the frequency signal of the coupled vibration f _k , φ1
represents a constant polyphase amount of the voltage induced in the transmitting/receiving vibration circuit with respect to the reference frequency.

In FIG. 2, which shows a device with a frequency measuring section, the same components as in FIG. 1 are provided with the same reference numbers. Insofar as the frequency measuring section requires modifications of the components of FIG. 1, the signs have changed. That is, the reference oscillator 9' with frequency divider, the control device 10' and the evaluation circuit 12' have changed sign. The difference from the device shown in FIG. 1 is that in FIG.
6 is provided, in which case the frequency of the received frequency signal is equal to the natural frequency of the coupled resonant circuits 2, 3. The frequency signal is supplied from the transmitting/receiving vibration circuit to a frequency measuring device 16 via an amplifier 15 during the receiving phase, and the frequency measuring device 16 is further supplied with a reference frequency from a frequency oscillator 9' having a frequency generator. .

Frequency can be measured over one or more signal periods of the frequency signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention which operates according to a time difference measurement method under a predetermined period, and FIG. 2 shows a method of measuring a received frequency signal using a frequency measuring device. 1 is a diagram showing a block diagram of an apparatus according to an embodiment of the present invention; FIG. DESCRIPTION OF SYMBOLS 1... Transponder, 4... Transmission/reception vibration circuit, 7... Transmission stage, 8... Receiving stage, 9... Reference frequency oscillator, 10... Control device, 11... Phase detector, 12... Evaluation Circuit, 13... Attenuation stage, 14
...Amplitude monitoring circuit, 16...Frequency measuring device.

Claims (1)

[Claims] 1. A transmitting stage for transmitting a frequency signal and a receiving stage are provided, the transmitting stage and the receiving stage are connectable to at least a transmitting/receiving vibration circuit, and are attached to a moving object. , having a coupled oscillating circuit controllable by measured values, through which a frequency signal can be supplied to the receiving stage, and operatively connecting the transmitting stage and the receiving stage alternately; transmitting a measured value from a moving object to a fixed object which is fixed relative to the moving object, and having a device for activating damping means of the transmitting/receiving vibration circuit in the meantime. In the transmitting device, at least one element (2 or 3) determining the natural frequency of the coupled oscillatory circuit can be changed continuously according to the measured value, and the receiving stage 8 comprises a phase detector 1.
1, the transmission device is configured as follows: during the transmission phase, the transmission stage sends the frequency signal to the transmit/receive vibration circuit, thereby transmitting the frequency signal to the transmit/receive vibration circuit. The transmitting/receiving oscillating circuit excites the coupled oscillating circuit, and subsequently, during a damping phase, the oscillations in the transmitting/receiving oscillating circuit are damped and reach the natural frequency of the coupled oscillating circuit only during the next receiving phase. from the moving object, characterized in that it is configured such that a frequency signal corresponding and continuously variable-adjusted according to the measured value is induced from the coupled oscillating circuit into the transmitting/receiving oscillating circuit. A device that transmits measured values to an object that is fixed relative to a moving object. 2. Device for transmitting measured values according to claim 1, wherein the coupled oscillatory circuit has an inductance 2 that varies depending on the measured value. 3. Device for transmitting measured values according to claim 1, wherein the coupled oscillatory circuit has a capacitance 3 that varies depending on the measured value. 4. An amplitude monitoring circuit 14 is provided, and the amplitude monitoring circuit 14 operates the frequency signal evaluation circuit device in the receiving stage only after the amplitude of the frequency signal exceeds a predetermined value. A device that transmits values. 5 A control device 10 is provided, and the control device 10
In the case of a predetermined period (N) of the reference frequency of the oscillator 9, the phase detector 11 is activated and the oscillator 9
A reference frequency of can be supplied continuously to the control device and to the phase detector 11 and can be supplied to the transmitting stage 7 as a frequency signal during the transmission phase, the phase detector being able to detect the reference frequency for one period. operative to measure the time difference between the next zero crossing of the frequency oscillation and the next zero crossing of the frequency signal received during the receive phase by the receiving stage, said phase detector converting said time difference into an analog signal. 2. Device for transmitting measured values according to claim 1, which is connected to an evaluation circuit arrangement 12 for conversion into a voltage. 6. The evaluation device has a voltage integrator, which is activated for the time difference detected by the phase detector and is connected to a detection circuit for subsequent detection of the integrated voltage value. A device for transmitting measured values according to claim 5. 7. A control device is provided, said control device activating the phase detector for a first period (N) of a reference frequency and a second period (N+M) following said period, said reference frequency being controlled by said control device. and to the phase detector continuously and to the transmitting stage as a frequency signal during the transmitting phase;
for the measurement of the time difference between the next zero crossing of the reference oscillation and the next zero crossing of the frequency signal received by the receiving stage during the receiving phase, during the Nth and N+Mth periods, respectively. Device for transmitting measured values according to claim 1, wherein the phase detector is activated and is connected to an evaluation circuit arrangement for subtracting the time difference and converting it into an analog voltage. . 8. The evaluation circuit arrangement has two voltage integrators, said voltage integrators being activated for one of the two time differences detected by the phase detector and connected to a voltage subtraction circuit. A device for transmitting the measured values described in range 7. 9 A transmitting stage and a receiving stage are provided for transmitting a frequency signal, and the transmitting stage and the receiving stage are connectable to at least a transmitting/receiving vibration circuit, are attached to a moving object, and are controllable by measured values. a coupled oscillating circuit, through which a frequency signal can be supplied to the receiving stage, the transmitting stage and the receiving stage being alternately operatively connected, and the transmitting/receiving stage being alternately connected; In a device for transmitting a measured value from a moving object to a fixed object that is fixed relative to the moving object, the device has a device for activating the means for damping the vibration circuit, At least one element (2 or 3) determining the natural frequency of the circuit can be changed continuously according to the measured value, and the receiving stage comprises a frequency measuring device 1.
6, the transmission device is configured such that during the transmission phase, the transmission stage sends the frequency signal to the transmit/receive vibration circuit, thereby transmitting the frequency signal to the transmit/receive vibration circuit. The transmitting/receiving oscillating circuit excites the coupled oscillating circuit, and subsequently, during a damping phase, the oscillations in the transmitting/receiving oscillating circuit are damped, and only during the next receiving phase, the natural frequency of the coupled oscillating circuit. from the moving object, characterized in that it is configured such that a frequency signal corresponding to and continuously varied and adjusted according to the measured value is induced from the coupled vibration circuit to the transmitting/receiving vibration circuit. A device for transmitting measured values to an object that is fixed relative to the moving object.