Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
  • H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes
  • H04B5/77—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes for interrogation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
  • B60C23/02—Signalling devices actuated by tyre pressure
  • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
  • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
  • B60C23/041—Means for supplying power to the signal- transmitting means on the wheel
  • B60C23/0413—Wireless charging of active radio frequency circuits
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
  • B60C23/02—Signalling devices actuated by tyre pressure
  • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
  • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
  • B60C23/0422—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver characterised by the type of signal transmission means
  • B60C23/0425—Means comprising permanent magnets, e.g. Hall-effect or Reed-switches
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
  • B60C23/02—Signalling devices actuated by tyre pressure
  • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
  • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
  • B60C23/0422—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver characterised by the type of signal transmission means
  • B60C23/0427—Near field transmission with inductive or capacitive coupling means
  • B60C23/043—Near field transmission with inductive or capacitive coupling means using transformer type signal transducers, e.g. rotary transformers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
  • B60C23/02—Signalling devices actuated by tyre pressure
  • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
  • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
  • B60C23/0422—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver characterised by the type of signal transmission means
  • B60C23/0433—Radio signals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
  • H04B5/40—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by components specially adapted for near-field transmission
  • H04B5/48—Transceivers

Definitions

• the invention relates to a device for transmitting signals by induction between a transponder circuit and an interrogation circuit.
• the transponder circuit comprises a first coil
• the interrogation circuit comprises a second coil.
• the transponder circuit is placed on an object capable of turning around at least one axis of rotation passing through the object, while the interrogation circuit is placed on a structure, which can be fixed, to which the object is connected.
• the rotating object can for example be a vehicle wheel, while the structure is for example the bodywork or the chassis of the vehicle.
• the transponder circuit includes at least one sensor for measuring a physical parameter. It can be a pressure sensor for measuring the tire pressure of the vehicle, a temperature sensor, a force sensor, an accelerometer or another type of sensor. The measurements made by the sensor or sensors of the transponder circuit can be transmitted to the interrogation circuit in the inductive signals, for example by amplitude modulation.
• the distance separating it from the interrogation circuit is not constant during the rotation of the object. Therefore, it is noted during the transmission of inductive signals between the interrogation circuit and the transponder circuit that a parasitic amplitude modulation of the signals occurs which can be a significant drawback. Thus, it may happen during demodulation operations in the receiving unit that the data received in the inductive signals do not completely correspond to the transmitted data. This disturbance on the transmitted data can also be dependent on the speed of rotation of the object. The higher the speed of rotation, the greater this disturbance can be.
• FIG. 1 shows in a simplified manner the influence that the rotation of an object can have on the amplitude of the inductive signals picked up by the receiving unit.
• Inductive signals are first transmitted by the transmitting unit at a determined carrier frequency and a determined amplitude.
• the data modulated in the inductive signals are not represented in this figure for simplification.
• the amplitude of the inductive signals picked up that is to say the amplitude of the voltage induced in the coil of the receiving unit, changes.
• this variation in amplitude is illustrated by the envelope of the inductive signals picked up by the receiving unit.
• This envelope is shown simply in sinusoidal shape corresponding to a constant speed of rotation of the object.
• the shape of this envelope is not in reality sinusoidal, since the amplitude of the magnetic field created by the transmitting coil does not decrease linearly with the distance separating the transmitting coil from the receiving coil.
• the transponder circuit transmits high frequency signals, it must in principle be provided with its own energy source, such as a battery. This can also be a disadvantage, because in this case the transponder circuit consumes energy even if the interrogation circuit does not interrogate it.
• an object of the present invention consists in providing a device for transmitting inductive signals which comprises means suppressing unwanted amplitude modulation of the inductive signals during the rotation of the object relative to the structure in order to alleviate the drawbacks of the prior art cited above.
• Another object of the present invention is to provide a device for transmitting inductive signals which is simple to produce while reducing manufacturing costs, and consumes little electrical energy.
• the invention relates to a device for transmitting inductive signals cited above which is characterized in that a coupling coil, provided with at least one turn, is mounted on the structure or on the object of coaxially with the axis of rotation of the object, said coupling coil serving as an interface for inductive coupling between the first coil and the second coil.
• the coupling coil makes it possible to serve as an interface between the interrogation circuit and the transponder circuit independently of the distance separating the first coil from the transponder circuit from the second coil from the interrogation circuit.
• the coupling coil having at least one annular turn, be mounted on the structure or on the object coaxially with the axis of rotation of the object.
• the first coil and the second coil can be considered as equidistant even with a rotation of the object.
• the transponder circuit comprises a passive transponder. In this way, the transponder circuit is only supplied by the inductive signals produced by the interrogation circuit. As long as the interrogation circuit does not produce inductive signals, the transponder circuit therefore remains at rest without electrical supply.
• the device for transmitting inductive signals is independent of manufacturing tolerances, in particular concerning the resonance frequency of resonant assemblies of each circuit.
• the inductive signals are at low frequency, for example of the order of 125 kHz.
• the transponder circuit comprises a resonant assembly constituted in particular by the inductance of the first coil and a capacitor mounted in parallel.
• the values of the inductance and the capacitor are chosen so as to define a resonant frequency close to the frequency of the signals transmitted by the interrogation circuit. This makes it possible to have a maximum amplitude of the inductive signals picked up, and to facilitate the storage of energy for supplying the components of the transponder circuit.
• the coupling coil is advantageously larger than the first coil of the transponder circuit and the second coil of the interrogation circuit.
• This coupling coil may comprise only a single annular turn in the form of a closed loop.
• the planes or axes of the turns of each coil are arranged parallel to each other.
• the first coil, seen in the axial direction is located in the closed loop of the coupling coil.
• the device for transmitting inductive signals is used for a vehicle.
• the transponder circuit and the coupling coil are preferably placed on one of the wheels of the vehicle, and the interrogation circuit is placed on a fixed structure which is for example the chassis or the body of the vehicle.
• the transponder circuit can also include at least one sensor for measuring a physical parameter. It may for example be a pressure sensor for measuring the pressure of a vehicle tire, a temperature sensor or a sensor for measuring the deformation of a tire.
• the measurements made by the sensor (s) can be stored in the transponder circuit when it is supplied, or transferred by the inductive signals to the interrogation circuit.
• the data is transmitted in the inductive signals preferably by amplitude modulation.
• FIG. 2 schematically shows a front view A and a side view B partially in section of an embodiment of the device for transmitting inductive signals, according to the invention, mounted on a wheel and a chassis of a vehicle;
• FIG. 3 schematically shows the various parts of the device for transmitting inductive signals according to the invention.
• FIG. 4 shows graphs relating to the transmission of data by amplitude modulation of the inductive signals between the interrogation circuit and the transponder circuit of the device for transmitting inductive signals according to the invention.
• the signal transmission device comprises a transponder circuit 1 preferably mounted on the tire 6 of a vehicle wheel 5, a magnetic coupling coil 2 of annular shape also mounted on the tire 6, and a circuit interrogation 3 mounted on a fixed structure of the vehicle, not shown, such as the chassis or the bodywork.
• the coupling coil 2 comprises one or more turns forming at least one closed loop.
• This coupling coil can be integrated into the structure of the tire 6 of the vehicle during its manufacture for example, or fixed on the outside or inside of the tire.
• the shape of this coupling coil is circular.
• This coupling coil is positioned on the tire 6 coaxially with an axis of rotation 9 which passes through the center of the rim 7 of the wheel of the vehicle 5.
• a rotation of the wheel around its axis of rotation does not modify the position of this coupling coil, in particular with respect to the interrogation circuit.
• this coupling coil 2 can also be mounted on the fixed structure coaxially with the axis of rotation 9 of the wheel.
• the transponder circuit 1 comprises a first coil not shown in this figure.
• the first coil can be produced for example on a flexible or rigid printed circuit board which carries the transponder integrated circuit.
• This first coil can comprise turns arranged in the same plane in the form of a spiral or wound in helical form around a magnetic core.
• the plane or the axis of the turns of this first coil is substantially parallel to the plane or the axis of the coupling coil 2 for better magnetic coupling between the two coils.
• the first coil, seen in the axial direction of the coupling coil is for example inside the closed turn (s) of the coupling coil.
• the transponder circuit 1 can be fixed on an outside side of the tire 6 as shown in FIG. 2, on an inside side of the tire, or on the rim 7.
• the coupling coil it could be envisaged to integrate the circuit transponder in the mass of the tire 6 during its production.
• the incorporation of the transponder circuit into the mass of the tire can pose certain manufacturing problems and does not allow said circuit to be changed in the event of a breakdown.
• the interrogation circuit 3 comprises a second coil 4, shown with a magnetic core for concentrating the lines of force of the magnetic field in order to improve the quality factor Q of this coil.
• the turns of this coil can be wound helically around the magnetic core.
• the plane or the axis of the turns of this second coil is substantially parallel to the plane or the axis of the coupling coil 2.
• this second coil 4 seen in the axial direction of the coil coupling 2 is located inside the closed coil (s) of the coupling coil.
• the carrier frequency of said inductive signals is preferably of the order of 125 kHz, that is to say at low frequency.
• the transponder circuit 1 As the transponder circuit 1 is mounted on the tire 6 of the wheel 5, it can comprise at least one sensor for measuring a physical parameter, such as the tire pressure, the temperature, the tire deformation, the speed of rotation . The measurements made by the sensor are transmitted by amplitude modulation in the inductive signals S2 to the interrogation circuit 3.
• the transponder of the transponder circuit 1 is preferably a passive transponder without its own power source, the interrogation circuit 3 must always transmit inductive signals S1 to the transponder circuit 1.
• the transponder circuit 1 can withdraw inductive signals received the electrical energy necessary for its operation.
• the coupling coil has been chosen with a large diameter to ensure good magnetic coupling.
• the number of turns of the first coil is preferably greater than the number of turns of the coupling coil, which may include only one closed turn.
• This coupling coil is located on the periphery of the tire 6 of the wheel 5. The inductance value of this coupling coil depends on the surface described by the closed coil (s).
• the mutual coupling inductance between the first coil and the coupling coil or between the second coil and the coupling coil depends on a coupling factor.
• This coupling factor takes into account the radius of each coil, the orientation of the turns of each coil and the distance between each coil. As the calculation of these different parameters is well known in the field of magnetic coupling, it is only stated the essential elements to be taken into account for a good dimensioning of each coil.
• FIG. 3 The various electronic components of the inductive signal transmission device are presented in a simplified manner in FIG. 3. It should be noted that the components of this figure, which correspond to those of FIG. 2, bear identical reference signs. It is shown in particular that the coupling coil 2 serves as a magnetic coupling interface between the first coil 10 and the second coil 4.
• the interrogation circuit 3 is presented in schematic form. It can be powered electrically via the vehicle battery. It includes an alternating signal generator, presented as an alternating voltage source Vo, connected to a capacitor Co in series with a coil 4 of inductance value Lo. Normally, the alternating signal generator comprises an oscillator and a data modulator, which are connected to an antenna drive device, not shown in FIG. 3.
• the oscillator produces signals at a determined frequency, for example 125 kHz , which corresponds to the carrier frequency of the inductive signals to be transmitted by the second coil 4, while the modulator makes it possible to connect or disconnect the oscillator in order to add digital data to the signals of the oscillator.
• the amplitude modulated signals which exit from the drive device, represent a binary sequence of information S1 to be transmitted to the transponder circuit.
• Each binary element of the sequence is defined over a determined period.
• a binary element of the binary sequence is worth 1 when the amplitude of the signals is maximum, while a binary element of the binary sequence is worth 0 when the amplitude of the signals is close to 0 in at least a period of time in a period of determined time of the binary element.
• This amplitude modulation by connection or disconnection of the oscillator is called an OOK (On-Off-Keying in English terminology) modulation.
• the data to be transmitted relates for example to the command to activate the transponder circuit, the command to transmit data, a specific time delay or parameters to be stored in said transponder circuit.
• a demodulator not shown, connected to the second coil 4 in order to demodulate data transmitted in the inductive signals S2 coming from the transponder circuit 1.
• a microprocessor unit can receive the demodulated data by the receiver for processing this data.
• the circuit called P4095 produced by EM Microelectronic-Marin SA in Switzerland, can be used as an interrogation circuit 3.
• the transponder circuit 1 is also presented in schematic form. The elements of this circuit are only reported in a summary, because they are part of the general knowledge of a person skilled in the art in this technical field.
• the transponder circuit notably includes a resonant assembly constituted by the first coil 10 of inductive value L1, a capacitor C1 mounted in parallel, and a resistor Rmod in series with a switch 11, which are connected to the first coil 10 and to the capacitor C1.
• the resistor Rmod is connected in parallel to the first coil 10 and to the capacitor C1 when the switch 11 is closed.
• the switch 11 is controlled by a logic part 12 of the transponder. By controlling the closing and opening of the switch, it is possible to amplify the inductive signals S2 for the transmission of data to the interrogation circuit.
• the values of the inductance L1 and of the capacitor C1 are chosen so as to produce a maximum amplitude of oscillation during the reception of the inductive signals.
• the resonant frequency of the resonant assembly is thus fixed as a function of the carrier frequency of the inductive signals received.
• the transponder circuit 1 stores the electrical energy received in a specific capacitor, not shown, so as to supply electrical power to all the components of the transponder circuit.
• timing clock signals of various operations performed in particular in the logic part 12 is also taken from the inductive signals picked up by the coil 10.
• This logic part can comprise at least one memory for storing any type of data.
• the transponder circuit 1 also comprises at least one sensor 13 for measuring a physical parameter.
• the sensor may be a pressure sensor for measuring the pressure of the tire on which the transponder circuit is mounted, a temperature sensor, a sensor for measuring the deformation of the tire or a speed or acceleration sensor. A combination of several sensors can also be envisaged.
• the sensor (s) 13 and the logic part 12 can be produced in the same semiconductor substrate, such as silicon.
• the measurements made by the sensor (s) are memorized and processed in the logic part 12 in order to control the closing or opening of the switch 11 for the transmission of this data in the inductive signals S2.
• the variation in amplitude of oscillation of the resonant assembly of the transponder circuit can be detected by the coil 4 of the interrogation circuit 3 using the magnetic coupling carried out by the coupling coil 2.
• the transmission of the data or binary sequence is made by the transponder circuit without interrupting the oscillation of the resonant assembly.
• the carrier frequency of the inductive signals S2 is therefore substantially the same as the carrier frequency of the inductive signals S
• Each binary element of the sequence is defined over a determined period. A binary element of the binary sequence is worth 1 when the signal amplitude is maximum, while a binary element of the binary sequence is worth 0 when the signal amplitude is reduced by a certain value by paralleling the resistive load Rmod in the resonant assembly.
• the circuit called P4150 produced by the company EM Microelectronic-Marin SA in Switzerland, can be used as transponder circuit 1.
• the transponder of this circuit is passive and operates at low frequency, for example at 125 kHz.
• Figure 4 shows on the upper graph of the inductive signals transmitted by the interrogation circuit and on the lower graph of the signals inductive transmitted by the transponder circuit.
• the upper graph and the lower graph show the variation in amplitude Au and Au of the inductive signals at carrier frequency determined as a function of the data to be transmitted.
• the data is transmitted according to a traditional binary sequence obtained by amplitude modulation.
• a binary element of the binary sequence is worth 1 over a determined period Tj when the signal amplitude is maximum, while a binary element of the binary sequence is worth 0 when the signal amplitude is close to 0 for at least a period of time in the determined period of a binary element.
• a binary element of the binary sequence is worth 1 over a determined period Tt when the signal amplitude is maximum, while a binary element of the binary sequence is 0 when the signal amplitude is reduced by some value.
• the determined period Tt is less than the determined period Tj so as to distinguish the data transmitted from the data received.
• the device can be applied in any field in which an object is rotatably mounted relative to a fixed structure. It can be partly mounted on a rotor of helicopter blades, in a steam turbine, on a carousel, or on any other rotor machine. It can be provided that the magnetic coupling coil has a polygonal shape while being positioned coaxially with respect to the axis of rotation of a rotating object, such as the vehicle wheel.
• the interrogation circuit and the transponder circuit can each be provided with a transmission coil and a coil for receiving the inductive signals.
• Frequency modulation can be used to transmit the data in the inductive signals to the instead of amplitude modulation.
• the frequency of the inductive signals transmitted can be different in each circuit.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)
• Near-Field Transmission Systems (AREA)

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• 2003
  • 2003-03-03 EP EP03004618A patent/EP1454769A1/de not_active Withdrawn
• 2004
  • 2004-03-02 EP EP04716214A patent/EP1608519A1/de not_active Withdrawn
  • 2004-03-02 WO PCT/EP2004/002057 patent/WO2004078495A1/fr not_active Ceased
  • 2004-03-02 US US10/547,413 patent/US7719406B2/en active Active

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