FR2529513A1 - DEVICE FOR MEASURING A PARAMETER IN A TIRE ON A WHEEL, IN PARTICULAR A MOTOR VEHICLE - Google Patents

Abstract

DEVICE FOR MEASURING A PARAMETER IN A TIRE ON A WHEEL, ESPECIALLY OF A MOTOR VEHICLE. THE DEVICE INCLUDES AN ASSEMBLY 7 LOCATED INSIDE A TIRE 3, INCLUDING A PRESSURE AND POSSIBLY TEMPERATURE SENSOR, AND CONNECTED TO TWO FRAMES 10, 11 LOCATED ON THE CENTRIPAL FACE OF RIM 2 AND FORMING, WITH FRAMES CORRESPONDENTS 12, 13 CARRIED BY THE BRAKE SHOE DEVICE, TWO CAPACITIES LINKED IN DIFFERENTIAL COUPLING TO OPERATING MEANS 17, ASSEMBLY 7 BEING POWERED BY AN INTEGRATED LITHIUM BATTERY, AND TRANSMITTING THIS INFORMATION TO THE OPERATING MEANS FSK CODING.

Description

Device for measuring a parameter in a tire

  on a wheel, especially a motor vehicle.

  _______________________________________________________

  The present invention relates to a device for measuring a parameter such as, for example, a pressure and / or a temperature inside a tire carried by a wheel, said device being applicable in particular to the measurement of the pressure or of the temperature inside a tire on one or more wheels of a motor vehicle such as for example a

car or heavy weight.

  A number of provisions have already been proposed

  intended to give an indication of the value of a parameter such as, for

a rotary member or a wheel.

  Most of these devices can provide only a limited indication of a definite value of the parameter causing the closing of an electrical contact, the reading of the corresponding information being performed at each wheel revolution at the time of the angular coincidence between the element carried by the wheel and a corresponding fixed element In addition to their inability to measure over a wide range of values, these devices are limited

  in their use, because when the rotational organ stops

  in a random position, it is impossible either to measure them or to ensure the transmission of a measurement that would have been made. These devices, which use an electro-magnetic coupling between the element carried by the wheel and the corresponding element fixene are furthermore in no way suitable for use in the

  motor vehicles, since they require

  the presence, both on the wheel and

  the wheel on a non-rotating part of the vehicle,

  incompatible electromagnetic devices, in practice,

  with the requirements of simplicity and hardiness that preside over

  replacement or dismantling by a small staff

qualified or by the general public.

  It has also been proposed to mount, on a

  wheel carrying a tire, a radio-electric transmitter

  that cooperating with a receiver mounted on a non

  Such devices may possibly

  even if the wheel stops in a random position Their use can not however be generalized because the regulations in force would oppose the radio interference that would be caused by the presence of such devices on many

  vehicles that would scramble each other.

  Finally, it has also been proposed to provide between two mechanical parts, which can rotate relative to one another, a capacitive coupling transmission using two capacities including the reinforcements

  are carried respectively by the two mechanical parts

  opposite, finally to ensure in a sense the trans-

  transmission of electrical energy from a frequency generator as well as remote control commands by frequency modulation of the generator, and in the other direction, information from highly measurement circuits emitting at a frequency / higher than the frequency However, the operating mode and the values, which are extremely different from the frequencies used, require that the capacitors have large surface plates spaced apart by an extremely small distance of the order of a millimeter. Such a device is in no way suitable for transmitting signals between a vehicle tire wheel and a fixed part of the vehicle in view of the difficult environment, the numerous parasitic effects likely

  to be present and the requirements of simplicity and ab-

  congestion due to the fact that the deposition, wheel replacements or

  level are carried out by people who have little or no

  lifiées. The present invention proposes to overcome these drawbacks and to provide a device for measuring at least one parameter such as, for example, the pressure and the temperature on a wheel provided with a tire, and in particular a motor vehicle wheel enabling it to be picked up. variable parameters at or in the tire, to transmit directly or possibly on demand, the parameter value or values adapted to a rotating structure ncn of the vehicle and exploit the

  information thus obtained, all in a reliable way.

  Another object of the invention is to provide such a device that can be implemented on motor vehicles without requiring actual modification or transformation of the wheels and

existing vehicle structures.

  Another object of the invention is to provide such a device which has a substantially zero space at the wheel and its assembly, allowing the installation, removal or repairs of wheels and related structures, including brakes, without requiring any intervention at the level of the device itself, these operations can be performed as in the past, by people without

no qualification.

  Yet another object of the invention is to provide such a device which is capable of operating in very different environments, of being adapted to wheels and vehicles of quite different natures and of accommodating extremely important variations. in games, gaps and tolerances of mechanical parts in the presence such as wheels, components, brakes, hubs, rockets etc. Another objective of the invention is that of providing such a device / while being adaptable to vehicles of typestout quite different, either from a

cost price lowered.

  Another objective of the invention is

  to provide such a device that does not require practical

  no maintenance intervention for a period of time

extremely long.

  The subject of the invention is a device for measuring at least one parameter, such as, in particular, pressure or temperature, at the level of a tire of a wheel, in particular a wheel of a motor vehicle, said wheel rotating around it. an axis carried by a fixed structure, that is to say non-rotating, in which the wheel comprises, in the tire / at this level, at least one sensor for this parameter with an associated electronic circuit, and the structure carries operating means responsive to the signals generated in said circuit, coupling means for transmitting said signals from the sensor circuit

  to said operating means carried by the structure

  fixed ture, characterized in that the coupling means comprise two capacities, preferably identical, each comprising two reinforcements, one of the armatures of the two capacities being fixed on the wheel and the other being fixed, facing, on the structure fixed so that the corresponding wheel frame scrolls in front of it, the capacities being mounted in

  connection with the sensor circuit and the means of ex-

  operation in differential transmission mode.

  The two wheel armatures are preferably fixed on the centripetal face of a wheel rim, the structural armatures being fixed opposite one another to the fixed structure. Particularly advantageously, a water less of the armatures of each capacity extends according to an entire circumference so that a part of this frame is always disposed opposite the second frame of the capacity Particularly advantageously, the frame extending over an entire turn is fixed on the wheel rim In a mounting on vehicles an automobile, / particularly advantageous feature of the invention lies in the mounting of a frame of

  each capacity on the wheel rim and the other arma-

  capacity on the periphery, close to the

  rim, disc brake or drum brake calliper device.

  Preferably, the spacing separating two armatures of the same capacity is between a few millimeters and a centimeter, this spacing may also vary without causing disturbances of the

transmission.

  According to a particularly advantageous embodiment of the invention, the coding and the transmission of the signals are carried out according to a PSK modulation, that is to say a frequency variation coding of the type, so that 'because of the differential transmission mode, the information from the sensor (s) is transmitted in a digital form which can be

  easily exploited by digital means of

  HAZARD. However, one could also, if need be, implement a frequency modulation coding or

  any other coding allowing proportional transmission

  information, that is, a significant number of different values of the physical parameter (s)

  pressure or temperature over an important measuring range

te and preferably continuous.

  According to a particularly advantageous characteristic

  In the invention, the electronic circuit associated with the sensor (s) comprises a source of electrical energy connected to the circuit or carried by the rotating wheel, such as a long-lasting battery, for example of the lithium type. Preferably, the capacitance frames consist of metal strips integrated in an insulating structure laminated so as to comprise a thin insulating support band whose one face is intended to be applied against the movable part such as the wheel rim or against the fixed structure and the other carries one or preferably two parallel metal strips, the band or strips and the visible part of the latter insulating strip face being covered with a second insulating strip preferably thinner than the first one. industrial, continuously, a complex band that is cut into the desired lengths to form the

  desired reinforcements Depending on the form of

  already described, cut a length each time

  corresponding to the perimeter of the internal or

  of a wheel rim and a second shorter length to be applied on the periphery, opposite the rim, a brake device, but one could also, alternatively, cut lengths for a ride complete both the wheel and the fixed part outside thereof, or lengths corresponding only to partial arcs of said circumferences, in which case a transmission in the stopped state in a random angular position

however, is not assured.

  Preferably, the one or more sensors and the associated electronic circuit are realized in the form of

  block embedded in an insulating resin, the circuit being itself

  The block advantageously comprises a pressure sensor, for example of the piezoelectric or quartz type, which is of a capacitive variation, or a resistive gauge, in direct connection with the atmosphere prevailing in the tire whereas the circuit integrated CMOS type can integrate temperature sensing means capable of delivering

  signals proportional to the temperature.

  Alternatively, the temperature sensor may be a conventional thermistor suitably inserted

  in the circuit or connected to it.

  Fixing the reinforcements, for example in the form

  stratified or laminated structure as described

  above, is preferably carried out by gluing on

  corresponding supports such as wheel rim and struc-

  brake, these reinforcements only forming an over-

  almost negligible on the opposite surfaces

  and not altering their appearance or shape.

  The capacitive connection between the sensor or sensors with the associated circuit, and the operating means can be mono-directional, the signals being then

  transmitted only from the armature connected to the cir-

  cooked to the second frames connected to the means of ex-

  However, preferably, the link can be bidirectional, signals such as signals

  order can then also be addressed to

  firing means of operation since said seconds

  reinforcements connected to the first armaments

  connected to the circuit and the sensor.

  In the latter case, the coding of the instructions thus addressed by the operating means to the wheel circuit is preferably of the FSK type and may be the frequencies used which may be close to or even identical to the frequencies used in the other direction, for the transmission of information corresponding to

  measurements made by the sensor (s).

  Particularly advantageously, the frequency range used is between 50 and 1000 kHz and

preferably between 100 and 400 kHz.

  The means of exploitation, which may advantageously

  include a microprocessesseur and various means of visualization

  Such electroluminescent diodes for displaying the results are preferably provided to exploit the parameters from a plurality of sensors mounted in the different wheels of a vehicle. Preferably, the information corresponding to the measurements, for example temperature and pressure, are transmitted

  successively from the different wheels in multi-

  temporal plexing, the control being carried out from the operating means These means decode the transmitted information and carry out the processing such as, for example, calculations, threshold deviations and overshoots, parameter gradients with respect to time, correlations between different wheel parameters, alarm signals etc.

  Other advantages and characteristics of the

  will appear on reading the following description.

  as a non-limitative example and refers to

  in the accompanying drawings in which: FIG. 1 represents a diagrammatic view in

  cut through a wheel with a device according to the invention.

  tion. Figure 2 shows a perspective view

part of this wheel.

Figure 3 shows a view

part of this wheel.

  FIG. 4 represents a view of a set of two frames in a FIG.

the element of Figure 4.

Figure 6 shows a view

the element of Figure 4.

  Figure 7 shows an elevational view of one in perspective

laminated system.

in elevation of

in cross-section

schematic of

  mounting a device for a plurality of wheels.

  FIG. 8 represents a schematic view in

  perspective of a sensor-circuit set.

  FIG. 9 represents a schematic view of a sensor-circuit assembly according to FIG. 8 mounted on the

  centrifugal face of a wheel rim.

  FIG. 10 represents an electrical block diagram

  of the associated sensor-circuit assembly. FIG. 11 represents a schematic block of

means of exploitation.

  Reference is first made to FIGS. 1 to 3.

  The wheel on which the device is to be mounted is a wheel of a motor vehicle. It comprises a disk-shaped sail 1 carrying a rim 2 of usual shape supporting a tire 3 without an air chamber. The wheel arch 1 is intended to be fixed by easily removable way, as is well

  on a hub part 4 carrying the disc 5 co-

  operating with a jaw brake device 6 of a very usual type This jaw brake device

  6 is mounted on a fixed structure of the vehicle, i.e.

say a non-rotating structure.

  Within the volume of pressurized air defined by the tire 3 is disposed, against the centrifugal face of the rim 2, an assembly 7 whose structure will be detailed later and which comprises one or more sensors such as a pressure sensor and / or

  of temperature sensitive to pressure and / or temperature

  This sensor is connected, by means of conductors 8, 9 diagrammatically represented, to two rim reinforcements 10, 11 each composed of a metal strip encapsulated in an insulating material as will be seen in detail. Each of the reinforcing ribbons 11 extends on the centripetal face of the rim 7 over the circumference thus afforded. When the wheel rotates, the two parallel armatures 10, 11 thus pass in front of two fixed armatures 12, 13 isolated from the same way and mounted on the face, in cylinder sector, of the braking device 6 which looks at the central part <of the rim 2 on which the rim reinforcements are fixed In this way, the rim reinforcement 10 scrolls exactly above of the fixed armature 12 and the rim armature 11 runs exactly above the fixed armature 13, the rim reinforcements and the fixed armatures being respectively separated by a free interval 14 of the order of 5 mm. conductors 15, 16 respectively connected to the frames 12 and 13 lead to operating means schematically shown at 17, the latter being supported by the vehicle body

  preferably the link thus formed by the conductors

  15 and 16 has a not shown connector, to allow easy removal of the device 6

who wears the frames 12 and 13.

  It is understood that in this way, the values of the physical parameters measured by the sensor or sensors of the assembly 7, suitably shaped if necessary by the associated circuit, form electrical signals transmitted by the conductors 8 and 9 to the frames 10 and 11 and by capacitive coupling, to the frames 12 and 13

  then, by the drivers 15 and 16, to the means of ex-

  The differential capacitive coupling is provided according to the invention for transmitting the

  information in F S K at a frequency preferably comprised

between 100 and 400 kHz.

  It is possible, without fear of effects

  parasites from the additional capabilities

  However, because of the existence of the different surrounding metal parts, or other electrical disturbances that are always possible, it is possible to transmit to the operating means 17 the desired signals corresponding to

  parameter measurements on ranges of

aunts, continuous or discontinuous.

  In the example shown, the different armaments

  However, it is understood that it would also be possible, depending on the geometries of the wheel parts and the adjacent fixed parts 1 1, to arrange the sets of fixed and movable armatures on the cylindrical geometric surfaces. other surfaces of revolution such as cones or disks By the way, thanks

  to the invention, fairly large variations can be tolerated.

  in the value of the gap 14 which separates the corresponding fixed and rotating reinforcement.

  not only absorb the specific tolerances

  It is also possible to mount one of the frames, such as the frames 12 and 13, on a fixed (non-rotating) support which, unlike the device 6, would be spaced from the rim of an interval.

  non-constant provided that this interval remains, for the purpose

  felt, confined within a range of a few millimeters laterally

  at about ten millimeters Similarly, displacements / are, tolerated.

  Reference is now made to Figures 4 to 6.

  In order to achieve the sets of two reinforcements described above, such as the set of reinforcements 10, 11 and the assembly 12, 13, it is advantageous to use a sheet or a strip of insulating synthetic material.

  such as for example an epoxy glass or a polyimide.

  This support 18 receives two parallel metal strips for example 10 and 11 having a thickness of the order of

  Nm, after which a new sheet of iso-

  lante 19, such as an epoxy glass or a polyimide, is applied on the assembly so that the metal parts 10, 11 scientcomplètement wrapped Outside the frames 10, 11 themselves, the insulating sheets

  18 come in contact to surround them.

  Instead of using metal ribbons to form the reinforcements, it is also possible to metallize the plastic or plastics material.

forming the insulator.

  Laminated or laminated arrays

  matures thus obtained can be manufactured continuously

  naked in great length to be then cut to the desired length, for example the length necessary to make a whole turn on the centripetal face of the rim

  2 and the length of the arc defined by the

braking system 6.

  The same manufacturing process can be used under these conditions, for applications to very different vehicles. It is understood that the set of frames 12, 13 could also extend over an entire turn of

  circumference rather than being limited to one sector, the

  10, 11 can possibly be used

  even extend only over a sector of circumference.

  The electrical connection between the conductors

  8, 9 and 15, 16, and the frames 10, 11, 12, 13 correspond to

  can be carried out in a variety of ways, for example

  after stripping or piercing one of the elements

  insulators preferably the support 18.

  The fixing of the assemblies thus constituted is

  preferably by bonding directly to the support, by producing a thin layer of adhesive 20 joining the support 18 to the metal part of the wheel such as the wheel channel. The adhesive may advantageously be a

epoxy glue.

  Preferably, the width of the reinforcementsis between 5 and 10 mm, the total width of an assembly such as that represented in FIG.

the order of 20 to 30 mm.

  Referring to FIG. 7, there is shown a circuit diagram in which the sets of four wheels are electrically connected by time multiplexing to a single operating device 17 making it possible to implement display means 21 such as electroluminescent diodes.

Referring to Figures 8-10.

  The assembly 7 comprises a lithium battery 22, a CMOS integrated circuit 23 and a piezoelectric pressure cartridge 24. The assembly is molded in a resin block 25 leaving a well 26 making it possible to communicate with the outside. pressure sensor 24 The block 25 is shaped so as to be able to fit into the rim portion 2 which receives it and to be fixed therein, for example by gluing.

  drivers 8, 9 coming from map 23

  weave a connector 27 profiled so as to pass through a hole in the rim, the conductors then continuing through the complementary part

  connector, to the frames 10, 11.

  The device may further comprise a heat

  28 unless the electronic circuit is used

  to provide the corresponding information

to the temperature variation.

  As we see more precisely on the

  FIG. 10, the circuit of the device 7 comprises a

  monitor receiver 29 connected toconductors 8 and 9, which

  is only fed from the battery 22

  that it is controlled by a signal from the means

  7, the alarm receiver triggers the alarm.

  controlled distribution 30 which at this time feeds the rest of the integrated circuit A sequencing logic 31 triggers successively, and through the switchman 32, a reading of the pressure sensor 24, for example gauge type implanted on silicon , the

  signal being calibrated by the calibrator 33, then a reading

  These analog value readings are converted to digital words by the digital analog converter. The digital words encode an FSK modulator loaded in differential mode by the capacitances composed by the armatures namely 10, 12 and 11. , 13 Then the integrated circuit is resting by

  via the controlled power supply 30.

  Referring to Figure 11, the means of exploitation are

  tation 17, to which the different drivers, 16 from different groups of two

  own wheels, have a suitable

  nable 36 using for example the vehicle battery and

  which, when turned on, powers a micro-

  processor 37 which starts the next sequencing

  A code generator 38 generates a code of error

  the electronic circuit of the assembly 7, which is switched successively by multiplexers 39, 40 towards the conductors 15, 16 and by the capacitive links, to the means 7 specific to the different wheels In return, as seen above, the set of wheels generates a response demultiplexed by 40 and 39, calibrated by a calibration member 41 and decoded

  by 42 to be processed by the microprocessor 37.

  This, according to its specific program, elaborates information that is presented to the means

  such as light-emitting diodes-

21.

  The latter are preferably arranged so as to allow a vehicle driver to read separately, for each wheel, the temperature values.

  and pressure prevailing inside the tire.

  Once the power supply 36 has ceased to be used, the device no longer consumes any electrical energy, with the exception of the very low energy required to keep the receiver

  29, this energy being obtained from the stack 22.

  Although the invention has been described with respect to a particular embodiment, it is understood that it is in no way limited and that

  make various modifications of form or

  without departing from either its setting or

his mind.

Claims (13)

  1 Device for measuring the monks a parameter, such as in particular pressure or temperature, at the level   of a single-wheel tire, in particular a wheel of a vehicle   3 cules automobile, said wheel rotating about an axis   carried by a fixed structure, in which the wheel   door, in the tire (3) or at least one sensor (24,28) with an electronic circuit   associated with it (7) and the structure   (17) sensitive to the signals generated in the said cir-   bake (7), coupling means for transmitting said signals from the sensor circuit to said operating means carried by the structure   fixed, characterized in that the coupling means com-   wear two capacities each with two frames   (10,12-11,13), one of the frames (10,11) of the two   cited being fixed on the wheel and the other (12,13) being fixed facing the fixed structure so that the corresponding wheel armature passes in front of it, the capacities being mounted in connection with the sensor circuit (7) and the operating means (17) in differential transmission.   2 Device according to claim 1, characterized   in both capabilities possess values equal.   3 Device according to any one of the   1 and 2, characterized in that the two wheel plates <10, 11) are fixed on the centripetal face of a wheel rim.   4 Device according to claim 3, characterized   in that the fixed armatures (12, 13) are fixed   on the peripheral face, close to the rim, a disc   positive (6) of brake shoes Device according to any one of claims 1 to 4, characterized in that the wheel armatures (10, 11) and / or the fixed armatures (12, 13) extend on a whole circumference.   6 Device according to any one of the   1 to 5, characterized in that the spacing (14) between the wheel plates and the fixed armatures is   between a few millimeters and a centimeter.   7 Apparatus according to any one of claims 1 to 6, characterized in that the coding and the transmission of the signals by the circuit (7) are effected according to a modulation F S K.   8 Device according to any one of the   1 to 7, characterized in that the circuit (7) associated with the sensor comprises a clean electrical source   (22) in particular a long life battery.   9 Device according to any one of the   1 to 8, characterized in that the armatures (10, 11-12, 13) are made of hollow strips comprising an insulating support strip (18) one of whose faces is intended to be fixed, in particular by gluing, on the wheel or the fixed structure and whose other face supports at least one strip-shaped armature, this other face and said armature being covered with a band covering (19).   Device according to any one of the   1 to 9, characterized in that the frequency of the transmitted signals is between 50 and 1000 kHz and in particular between 100 and 400 kHz.   11 Device according to any one of the   1 to 10, characterized in that the associated circuit The sensor is of the CMOS type.   12 Device according to any one of the   1 to 11, characterized in that said circuit and the at least one sensor are wrapped in a resin block, an orifice (26) for communicating a pressure sensor (24) with the atmosphere inside the tire, and a connecting connector (27) being provided for the electrical connection with the reinforcements rim (10,11).   13 Apparatus according to any one of the   1 to 12, characterized in that the associated circuit   the sensor is sensitive to control signals   from the means of exploitation (17).   14 Apparatus according to claim 13, characterized in that the associated circuit comprises a standby receiver (29) connected to the rim reinforcements (10,11), a power supply cell (22), a controlled power supply (30). triggered by the standby circuit, a sequencing logic (31) driving a switch (32) for successively reading a pressure sensor (24) and   a temperature sensor (28), an analog converter   digital receiver (34) receiving said reading and a modu-   F S K (35) loaded with differential mode by   said armatures (10,12) capabilities.   Device according to any one of the   Claims 1 to 14, characterized in that the operating means (17) comprise a feed (36)   which controls a microprocessor (37) controlling a gen-   trigger code (38) to which the circuit   associated with the sensor is sensitive, means of   plexing (39,40) connected to the fixed armatures (12,13) 'of a plurality of sensors corresponding to a plurality of wheels, a calibration member (41) receiving the response   demultiplexed by the multiplexers, a decoder (42) -   returning the information to the microprocessor (37), and viewing means (21).