FR2500926A1 - DEVICE FOR TRANSMITTING A MEASURED SIZE FROM A MOBILE OBJECT TO A STATIONARY OBJECT IN RELATION TO THE SAME - Google Patents

Abstract

THE INVENTION RELATES TO A DEVICE FOR TRANSMITTING A MEASURED QUANTITY FROM A MOBILE OBJECT TO A STATIONARY OBJECT IN RELATION TO THE LATTER. THIS DEVICE INCLUDES A TRANSMITTER STAGE 7 AND A RECEIVER STAGE 8 WHICH CAN BE CONNECTED TO AN OSCILLATING TRANSMITTER-RECEIVER CIRCUIT 4; AN OSCILLATING CIRCUIT OF COUPLING 2, 3 BY MEANS OF WHICH A FREQUENCY SIGNAL CAN BE APPLIED TO THE RECEIVER STAGE 8; AS WELL AS MEANS WHICH CAN ALTERNATIVELY CONNECT THE TRANSMITTER STAGE 7 AND THE RECEIVER STAGE 8 AND WHICH POSSIBLY ACTIVATE INTERCAL MEANS TO DAMP THE SIT OSCILLATING CIRCUIT TRANSMITTER-RECEIVER 4. AT LEAST ONE ELEMENT 2, 3 DETERMINING THE OD-FREQUENCY OSCILLANT COUPLING 4 MAY CONSTANTLY BE INFLUENCED BY THE MEASURED VALUE, AND THE RECEIVER STAGE 8 IS EQUIPPED WITH A PHASE 11 DETECTOR. APPLICATION IN PARTICULAR TO ON-BOARD COMPUTERS EQUIPPING MOTOR VEHICLES.

Description

The present invention relates to a

  positive value for transmitting a measured quantity, of a target

  mobile jet to an object stationary with respect to the latter, in particular from the wheel to the chassis of a motor vehicle, comprising an emitter stage delivering a frequency signal and a receiver stage which can be at least connected to an emitter-oscillating circuit. receiver; an oscillating circuit

  coupling device, arranged on the moving object, which can be

  d by the measured quantity and through which

  a frequency signal may be applied to said receiving stage

  tor; as well as means that connect alternatively

  the transmitter and receiver stages and possibly activate

  between the latter means intended to cushion

  said transceiver oscillating circuit.

  In a device of this type known from

  the prior art, the oscillating coupling circuit is made

  transponder (pulse-coupled transceiver), which further includes a switch

  to be opened and closed according to the value of the pressure

  when controlling the tire pressure of a vehicle, this switch thus damping the coupling oscillation circuit to a relatively

  weak, or almost bypassing this circuit.

  In this way, using the part of the device incorporated in the chassis of the vehicle, it can be determined whether the

  air pressure dropped below a predetermined value.

  For this purpose, the transmitter stage is first connected in such a way that it transmits via the oscillating transmitter-receiver circuit a frequency signal which is received by the coupling oscillating circuit when the latter

  is located close to said emitter-oscillating circuit

  receiver. The energy of the signal in frequency, coupled magnetically

  quen.t to a coil of the oscillating circuit of coupling, makes os-

  the latter at its natural frequency when the switch

  is open. When this switch is closed, no

  tion does not occur in the coupling oscillation circuit.

  Thus, the transceiver oscillating circuit can be

  cushioned by a control unit, so that

  The events that are still visible after the triggering of the transmitter stage decrease very rapidly. Then,

  the oscillating transceiver circuit is connected ef-

  the receiving floor, also through the

  of the control unit. In the case where the transponder switch is open and thus a decreasing oscillation occurs in the coupling oscillation circuit, this frequency signal is received by the transceiver oscillating circuit during the reception phase.

  when -this circuit is near the oscil-

  during this phase of reorganization.

  ception, no signal is received by said transceiver oscillating circuit when the switch is closed. To interpret or translate the signal into a received frequency, the receiving stage

  may include an electronic counter at the entry of

  ge of which are applied for a predetermined time interval counting pulses formatted and produced from the received frequency signal. The contents

  the meter then indicates -that the transpon-

  is open, when a predetermined value is reached during the time interval, while,

  otherwise, when the transpon-

  is closed, no pulse reaches the meter and a display stage indicates that the pressure is too high

low.

  The disadvantage of this device lies in the fact that only two measured discrete quantities

  can be transmitted without contact, depending on whether

  transponder is open or closed by

measured.

  It is also known in the prior art

  a device for transmitting at least one measurement quantity

  from a moving object to a fixed object with respect to the latter and comprising an emitter stage generating two emission signals at different frequencies, at least one coupling element combining these two frequencies and

  attached to the moving object, as well as a receiving stage that

  git at a combined frequency. The combined coupling element

  The two frequencies consist of at least one oscillating circuit which contains a component whose current voltage has a linear characteristic curve. For this purpose, it is possible to provide a diode or a transistor whose base-collector circuit is short-circuited. When the

  the interrupter of the coupling element is open, this element

  does not deliver any signal in frequency. On the other hand,

  when its switch is closed, this coupling element

  ge delivers a signal whose frequency corresponds to the difference

  between the different frequencies of the transmission signals.

  This differential frequency signal is picked up by the receiver stage and is used to

  operate an alarm device. When using

  for example, two coupling elements for each tire.

  of a vehicle to transmit a signal depending on

  With regard to temperature and pressure, it is necessary to provide the central unit comprising the transmitter stage and the receiver stage with an additional stage which compares the phase of the received signal with that of a reference signal of the same. frequency generated in the central unit,

  as well as another alarm device. How-

  even when using two coupling elements and phase comparison in the CPU, only two measured values for each of the two

  measurement quantities are captured and distinguished.

  The object of the present invention is to provide a device of the aforementioned type so that it can be permanently captured.

  measured values that are transmitted from a moving object

  to a stationary object in relation to the latter.

  According to the essential characteristics

  of the device of the invention, at least one determinant element

  the natural frequency of the coupling oscillation circuit may be constantly influenced by the measured value and

  the receiver stage is equipped with a phase detector.

  This device can continuously detect values of a quantity to be measured, transmit them without

  contact and interpret them in a central unit

  the emitter stage and the receiver stage. A characteristic

  particular feature of this device lies in the fact

  that the oscillating coupling circuit constitutes a

  transponder, the coil of this circuit serving

  coupling element and said circuit comprising a

  Continuous value inverter which converts the quantity to be measured into a change-of state of at least

  an element of said coupling oscillating circuit.

  The measured value converter of the

  baked oscillating coupling may consist of the coil

  (inductance), that the measured value can vary.

  A capacitor whose capacity varies according to the measured value fulfills the same function. In the

  In two cases, when the measured value varies, the os-

  coupling system maintains a high level of reliability

  sure to this coupling oscillation circuit of good

  transmission tees. The transmission of the measured value presupposes at least a minimum coupling of the coil of the coupling oscillating circuit and the oscillating circuit

  transceiver, this coupling being determined for the purpose

  sensel by the distance separating these coils.

  In the central unit, the transceiver oscillating circuit is used as an antenna during a transmission phase and a frequency of

  reference in the form of a frequency signal. The frequency

  the frequency of this signal preferably corresponds to the frequency

  resonance of the transceiver oscillating circuit. Pen

  in the transmission phase, the coupling oscillating circuit oscillates at the frequency which is also equal to the reference frequency and which only shows a phase difference with respect to the emitted frequency signal. At the end of the transmission phase, the oscillation of the coupling oscillation circuit, which itself generates a frequency signal begins to decrease, and that at a frequency which is equal to the frequency

  own of said coupling oscillating circuit. This oscil-

  decreasing lation also has a particular phase which depends on the resonance frequency of the circuit

  oscillation coupling, in relation to the reference frequency

  initially transmitted in the form of the frequency signal.

  Thus, when the coupling oscillating circuit is

  near the oscillating transmitter-receiver circuit, the oscillator

  The coupling of this coupling oscillating circuit induces a signal whose frequency is equal to that of the decreasing oscillation of said coupling oscillating circuit.

  and whose phase is shifted with respect to the latter. com-

  moderately, when the transceiver oscillating circuit

  is common to both the transmitter and receiver stages.

  this circuit is amortized to allow for a rapid transit

  from the transmission phase to the reception phase between

  two phases, so that any oscillation rapidly decreases

  in this circuit. The oscillation induced in the transceiver oscillating circuit during the reception phase is then conveniently amplified in the central unit and is interpreted by a phase detector. This detection of the phase can take place efficiently and reliably during a small number of oscillations whereas these

  decreases, which is particularly important

  with regard to the displacement of the oscillating circuit of

  range to the oscillating transceiver circuit. As will be seen hereinafter, this phase detection is conveniently

  performed as a measure of time.

Instead of detecting phase

  of the frequency signal which is again coupled in the cir-

  oscillating transmitter-receiver during the reception phase

  tion and from the oscillating coupling circuit, it is also possible to use a frequency meter when the latter is made in such a way that it allows a reliable measurement

  frequency during a small number of oscillations.

  As well, the measurement of oscillations decreases

  in the oscillating coupling circuit by means of a detection

  only by measuring the frequency

  that the result of the measurement is not influenced for.

  most importantly by the resonance acuity of the oscillating circuit

  coupling, which depends in certain circumstances

  conditions for incorporating the object to be measured,

  close to metal parts.

  Conveniently, in the central unit, the device comprises amplitude control means, which does not initiate the interpretation of the frequency signal.

  in the receiver stage only when the amplitude of this

  frequency signal exceeds a predetermined value. We

  avoid any misinterpretation when the cir-

  baked oscillating coupling is too far from the circuit

  oscillating transceiver to provide information

  safe indication of the phase or frequency of the received signal. Moreover, the frequency signal returned by the coupling oscillating circuit

  also induces in the transmitter-receiver oscillating circuit

  An oscillator is considered to be stationary an oscillation which first of all grows when said transceiver circuit is oscillated and then decays exponentially as a function of the oscillation in the coupling oscillation circuit. It thus establishes during the emission phase a

  short time period during which the signal in frequency

  The received quency has a maximum amplitude. During this

  time interval that covers a few

  the sensitivity of the device and the precision of the

sure are maximum.

  In an advantageous embodiment of the device for interpreting or translating the frequency-received signal

  which indicates a continuous measured value, this device

  carries a control unit which activates (activates) the phase detector for a given number N of periods of a reference frequency (oscillator) which can be permanently applied to said control unit and to the phase detector and which can be applied to the transmitter stage in the form of a frequency signal during a transmission phase; said phase detector is designed to

  measure the time interval between the following zero crossing

  the reference oscillation and the next zero crossing of the frequency signal received by the receiver stage

  during the reception phase, during a period; and the-

  said phase detector is connected to an interpreter unit

  tation which is intended to transform the time interval into a corresponding voltage. Thus, this device comprises as a phase detector in the receiver stage of

  means for measuring the time interval, during a period

  determined from the reference frequency, between a zero crossing of this reference frequency and a following zero crossing of the fault signal received by the receiving stage

  and having been induced by the oscillation in the oscillating circuit

  coupling. This measure can be carried out favorably

  during a period of the received frequency signal.

  In this case it is advantageous that this measurement can take place independently of external additional signals of rhythm or frequency. On the contrary, all the rhythm signals can be derived, in the central unit, from a

  single oscillator, by means of a divider.

  In an advantageous embodiment of the time interval interpretation unit obtained in the aforementioned manner, this interpretation unit comprises a voltage integrator which is activated during the time interval determined by the detector.

  phase and which is connected to a detection circuit

  detecting immediately after the voltage value in-

  tégrée. The voltage integrator can then, so

  simple, consist of a circuit type RC (resistance-

  capacity) powered by a constant current.

  In another embodiment, the device comprises a control unit which activates the phase detector during a first number N of periods and a second successive number N + M of periods

  a reference frequency which can be applied

  to said control unit and said phase detector and can be applied to the transmitter stage during

  an emission phase; said phase detector is intended

  to measure the time intervals between the next zero crossing of the reference oscillation and the passage through

  following the frequency signal received by the receiving stage

  during the reception phase, during the Nth and N + Mth periods, respectively; and said phase detector is connected to an interpretation unit which is intended to subtract said time slots and

  convert them to a corresponding voltage. In this va-

  As an embodiment of the invention, the device comprises, as a phase detector, means which measure the time interval between the zero crossings of the reference frequency.

  this and the frequency signal received during several

  but, overall, for a relatively short time.

  The unit of interpretation equipping the dis-

  positive presents two voltage integrators which are activated respectively during each of the time intervals indicated by the phase detector and which are connected

  to a voltage subtraction unit.

  Finally, the frequency of the received signal can also be interpreted directly using a frequency meter, with the aforementioned restrictions that implies. In this case, at least one element determining the natural frequency of the coupling oscillation circuit can be constantly influenced by the measured value and the stage

  receiver is equipped with a frequency meter.

  The invention will now be described in more detail with reference to the accompanying drawings by way of non-limiting examples and in which:

  Figure 1 is a diagram illustrating the

  positive that operates on the principle of measuring the time interval during a specified period; and FIG. 2 is a diagram illustrating said device in which the measurement of the frequency signal

  received is executed by a frequency meter.

  In FIG. 1, the reference 1 designates a transponder or responder whose coupling oscillating circuit includes a coil

  2 and a capacitor 3. When the coil or -

  the capacitor constitutes a measurement converter, it is possible to permanently adjust the resonance frequency of the transponder as a function of the quantity to be measured. The transponder is attached to a part

  mobile, for example the wheel of a vehicle.

  In the transponder movement range,

  an oscillating circuit 4 transceiver, mounted on the

  fixed circuit, comprises a coil 5 and a capacitor 6. This oscillating transceiver circuit receives a signal in

  frequency of a transmitter stage 7, or else it de-

  delivers a received frequency signal to a receiver stage 8.

  Both the transmitter stage and the receiver stage form part of a central unit which comprises an oscillator 9 generating a reference frequency, and a

control unit 10.

  The oscillator supplies both the control unit 10 and the transmitter stage 7 and a phase detector 11 of the receiver. The output of the transmitter's phase detector is connected to an interpretation unit

or translation 12.

  The transmitter stage, a damping stage 13 of the oscillating circuit 4 transceiver and the detector

  phase 11 receive control signals issued by the

  order. Similarly, this control unit 10 applies

  a control signal to an assembly 14 for con-

  to control the amplitude. This assembly 14 is also powered by the oscillating transceiver circuit

  and it transmits a control signal to the unit of inter-

interpretation 12.

  The assembly 14 operates in such a way that, during a transmission phase, the transmitter stage

  applies the amplified reference frequency of the oscilla-

  9 to the oscillating circuit 4 transceiver, which then excites the transponder 1 when the latter is in the vicinity of said transceiver oscillating circuit. This immediately results in a decrease of oscillations in the transceiver oscillating circuit during the damping phase. When the transponder is in the vicinity of this oscillating transceiver circuit, it induces in the latter, during the reception phase, a frequency signal which corresponds to the natural frequency of the circuit

  oscillation coupling comprising the coil 2 and the condensate

  3, this frequency can be constantly

  adjusted according to the measured value.

  In the receiver stage, the measurement takes place in such a way that the phase detector is released by a control signal "activation of the phase detection" which is emitted by the control unit 10. Thus, for a predetermined period , the phase detector measures the time interval between the next edge of the reference frequency signal (for example during the zero crossing) and the corresponding edge of the received frequency signal. This timing signal is converted in the interpretation unit 12 into a corresponding voltage when the amplitude control unit 14 signals an amplitude of the frequency signal.

  received insufficient to allow a suitable measure. The con-

  version of the corresponding voltage time interval

  can take place by charging a capacitor of a type RC (resistance-capacitance) mounting, using

  constant current. The capacitor voltage is

  subsequently transmitted through a detection unit.

  According to this measurement principle, a measurement can take place during a phase-phase transmission cycle

  damping-reception phase (clock period).

  The time interval between passes through

  zero for a given Nth period (reference frequency

is equal to

(AT) N N (4-

  N = f fk 2wfk o (AT) N is the time interval between the zero crossings of

  the reference frequency fr and the frequency signal

  quence of the coupling oscillation fk; and

  41 is a constant phase shift of the internal voltage

  in the oscillating transceiver circuit

  relative to the reference frequency.

  In FIG. 2, in which the device is equipped with a frequency meter, the same

  components are assigned the same numerical references.

  When the measurement of the frequency causes a modification of the elements of FIG. 1, the numerical references are

  modified: this is the case for the mounting 9 'of the oscilla-

  reference transmitter and a divider, for the control unit 10 'and 11 for the interpretation unit 12'. Unlike the arrangement

  of FIG. 1, there is provided in FIG.

  meter 16 for indicating the frequency of the signal received by the transceiver oscillating circuit, the frequency of which is equal to the natural frequency of the coupling oscillating circuit 2, 3. This frequency signal originating from the transceiver oscillating circuit is applied ,while

  the reception phase, via an amplification

  15, the frequency counter 16 which receives a reference frequency of the assembly 9 'of the reference oscillator and

of the divisor.

  The frequency can be measured during one or

  several periods of the signal in frequency.

  It goes without saying that many modifications can be made to the device described and shown,

  without departing from the scope of the invention.

Claims (9)

  1. Device for transmitting a large   measured from a moving object to a stationary object relative to the latter, in particular from the wheel to the chassis of a motor vehicle, comprising a transmitter stage which transmits a frequency signal and a receiver stage, these stages being connectable to the less to an oscillating transceiver circuit; a coupling oscillation circuit which, arranged on the moving object and controllable by the measured value, can apply a frequency signal to the receiver stage; as well as means which alternately connect the emitter stage and the receiver stage and activate or possibly activate means between the latter to damp the said transceiver oscillating circuit, characterized in that at least one element (2 3) determining the frequency   of said coupling oscillation circuit can be   influenced by the measured value and the fact that   the receiver stage (8) is equipped with a phase detector (11).   2. Device according to claim 1, characterized in that the coupling oscillating circuit comprises an inductor (coil 2) which can be influenced by the measured value.   3. Device according to claim 1, characterized in that the coupling oscillating circuit comprises a capacitor (capacitor 3) that can be modified by the measured value.   4. Device according to any one of   Claims 1 to 3, characterized in that it comprises   means (14) for controlling amplitude, which does not initiate   the interpretation of the frequency signal in the receiver stage   only when the amplitude of this signal exceeds a predetermined value. 5. Device according to any one of   Claims 1 to 4, characterized in that it comprises   a control unit (10) which activates the phase detector for a given number (N) of periods of a reference frequency (oscillator 9), which can be permanently applied to said control unit and to the detector of phase (11) and which can be applied to the transmitter stage (7) in the form of a frequency signal during a transmission phase; in that the phase detector   is intended to measure the time interval between the   zero-following ge of the reference oscillation and the next zero crossing of the frequency signal received by the receiving stage during the reception phase, during a period; and in that said phase detector is connected to an interpretation or translation unit (12) which is intended for   convert the time interval into the corresponding voltage.   6. Device according to claim 5, characterized in that the interpretation unit comprises   a voltage integrator that is put into action during the in-   time determined by the phase detector and which is connected to a detection circuit enabling   detect immediately after the value of the integrated voltage.   7. Device according to any one of   Claims 1 to 4, characterized in that it comprises   a control unit that activates the phase detector   during a first number (N) of period and a se-   cond successive number (N + M) of periods of a reference frequency which can be permanently applied to said control unit and said phase detector and which can be applied to the transmitter stage in the form of a signal. frequency during an emission phase; by the fact that   said phase detector is intended to measure the intervals   the time between the next zero crossing of the oscilla-   reference and the following zero crossing of the frequency signal received by the receiver stage during the reception phase, respectively during the Nth and N + Mth periods; and in that said phase detector is connected to an interpretation unit for subtracting the time slots and converting them into corresponding voltage.   8. Device according to claim 7, characterized in that the interpretation unit comprises two voltage integrators which are actuated during   each of the two time intervals determined by the de-   phase detector and which are connected to a sub-circuit tension pull.   9. Device for transmitting a large   measured deur from a moving object to a stationary object relative to the latter, in particular from the wheel to the chassis of a motor vehicle, comprising a transmitter stage which transmits a frequency signal, and a receiver stage, these stages being connectable at least one transceiver oscillating circuit; a coupling oscillation circuit which, arranged on the moving object and controllable by the magnitude to be measured, can apply a frequency signal to the receiver stage; as well as means which alternately connect the transmitter stage and the receiver stage and activate, if necessary, means between   these latter for damping said emitter-oscillating circuit   receiver, characterized in that at least one element (2; 3) determining the natural frequency of said coupling oscillating circuit can be constantly influenced by the measured value, and by the fact that the receiving stage has a frequency meter (16).