Classifications

• • 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
  • B60C23/0435—Vehicle body mounted circuits, e.g. transceiver or antenna fixed to central console, door, roof, mirror or fender
  • B60C23/0444—Antenna structures, control or arrangements thereof, e.g. for directional antennas, diversity antenna, antenna multiplexing or antennas integrated in fenders
• • 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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L17/00—Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies

Definitions

• the present invention relates to a device for measuring without contact the pressure of a gas en ⁇ closed by a body, e.g. the air pressure in a vehicle tyre.
• a dia- phragm of an amorphous magnetic transmitter material is used, which is exposed -at one side thereof to the pressure of the gas enclosed by the b idy, and at the-, other side thereof to a reference pressure.
• This system based on the use of an amorphous magnetic material in the diaphragm makes use of the known fact that the permeability ( ) of such materials is directly dependent on the state of mechanical strain in the material. If said state is changed, also the permeability of the material will be chang- e .
• a solenoid connected to a drive unit is mounted adjacent the transmitter diaphragm to generate a magnetic field passing through the diaphragm.
• a magnetic measuring unit By means of a magnetic measuring unit forming part of the system, changes in such properties of the magnetic diaphragm as are caused by deformation of the diaphragm, i.e. the permeability of the dia ⁇ phragm, are determined.
• An advantage of this prior art system is that the changes of the permeability can be indicated magnetically in a simple manner.
• a drawback of the prior art system is that the reliability of the measurement values is de ⁇ pendent on the fact that the diaphragm and exciter and pick-up coils are mounted in fixed positions in relation to each other and that these positions are kept unchanged.
• the amplitude of the measurement signal obtained represents the permeability of the diaphragm comprising an amorphous material, and thus represents the state of mechanical strain in the diaphragm, which in turn is dependent on the press- ure to which the diaphragm is exposed.
• the amplitude of the measurement signal also is highly dependent on the distance and the bearing of the measured object. If the distance and/or. the bearing of the measured object is changed, also the a pli- tude will be changed.
• the object to be measured is moving in relation to exciter and pick-up coils as may be the case e.g. when the r pressure of a vehrcle tyre is being measured, the reliability of the signal obtained will be impaired because such signal will be affected of distance and bearing changes as well as permeability changes of the diaphragm.
• a dia ⁇ phragm of a non-amorphous material is used.
• the dia- phrag is attached at the centre thereof to one end of a string the other end of which is attached to a fixed structure.
• the string is prestressed. Changes in the bulging of the diaphragm make the tension of the string increase or decrease, which influences the natural frequency of the string.
• By measuring the natural frequency of the string there is accordingly obtained a measure of the bulging of the diaphragm and thus a measure of the resulting pressure causing said bulging of the diaphragm.
• the advantage of this system is that it is the frequency and not the amplitude that carries the information desired.
• Frequency signals in fact are not as sensitive to disturbance and to attenuation as are amplitude signals.
• a drawback of the prior art system is that such a system does not allow remote indication; it is a prerequisite that transmitter and sensor elements are constructed as a unit in close relationship.
• the purpose of the present invention is to pro- vide a device of the kind referred to above for measuring without contact, which combines the ad ⁇ vantages of the two systems described above and at the same time avoids the drawbacks of said systems and which thus makes possible to measure without contact and substantially ' independently of distance and bearing by 'using simple magnetic measuring technique.
• FIG. 1 shows diagrammatically the application of the invention to measurement of the pressure in a vehicle tyre
• FIG. 2 shows diagrammatically an alternative embodiment of a device of the invention for measuring the pressure in a vehicle tyre
• FIG. 3 is a graph showing an example of the permeability change of the amorphous trans ⁇ mitter element in response to the mechanical strain thereof
• FIG. 4 is a graph showing an example of press ⁇ ure variations and corresponding changes in the permeability of the transmitter element and, super- posed thereon, changes in the permeability caused by the natural frequency of the diaphragm. ⁇
• the test object comprises a vehicle tyre 8.
• a measurement chamber 1 Inside the vehicle tyre a measurement chamber 1 is mounted, having a transmitter diaphragm 2 of an amorphous magnetic transmitter material also termed METGLAS attached thereto.
• the transmitter diaphragm 2 to— gether with the measurement chamber 1 defines a re ⁇ ference pressure chamber 3 having the pressure p .
• the measurement chamber 1 at the side facing away from the reference pressure chamber 3 communicates via apertures 9 with the air volume enclosed by the tyre.
• the pressure in the test object , i.e. the tyre pressure, thus affects the transmitter dia ⁇ phragm 2 from the outside thereof, said diaphragm being deformed.
• two solenoids 4 are connected to the sur- rounding stationary structure, said solenoids being kept in position by an attachment 5.
• the solenoids 4 are connected to a drive and measuring unit 6 for generating a magnetic field which passes through the transmitter diaphragm 2.
• the deformation of the dia- phragm 2 is determined by measuring the relative permeability ( ⁇ -measurement) , the changes of the natural frequency of the diaphragm being determined and converted into a corresponding pressure value which is indicated or shown on a display unit 7.
• FIG. 2 shows diagrammatically an alternative embodiment of the device of the invention as used for measuring the pressure in a vehicle tyre.
• the device comprises a sleeve 10 having an outside thread 11 and a closed bottom 12.
• the sleeve 10 is intended to be sealingly screwed into the rim 13 of a vehicle tyre with the opposite end of the sleeve projecting into the cavity of the tyre supported by the rim.
• the transmitter comprises a diaphragm 14, in the centre of which one end of a strap 15 is attached said strap being made of an amorphous magnetic transmitter material.
• The. opposite end of the strap 15 is attached to a non-magnetic portion 16 of the bottom of the socket.
• the strap is prestressed by tension, the strap as a con- sequence" thereof has a determined permeability and a determined natural frequency.
• non-rotatable wheel suspension activat ⁇ ing and pick-up coils are mounted which are connect ⁇ ed to a measuring and drive unit in a way corre- sponding to that in the previous example. For each revolution of the wheel one measurement of the pressure will be obtained.
• the pressure in the tyre When the pressure in the tyre is changed the bulging of the diaphragm 14 and -thus the mechanical strain in the strap 15 will be changed. Then, also the permeability and the natural frequency of the strap will be changed correspondingly, such change being indicated by the measuring unit.
• the measure ⁇ ment value will not be dependent on the distance because the natural frequency of the oscillation progress in the prestressed strap 15 is defined by the mechanical tension of the strap only.
• the strap 15 forming the transmitter element thus is com ⁇ pletely passive and requires no power supply of its own. The self-oscillation will be initiated by the coil in the stationary portion.
• FIG. 3 shows a graph illustrating the variation of the permeability of the amorphous magnetic trans ⁇ mitter in response to the mechanical tension there- in.
• the tension O * corresponding to the prevailing pressure p is indicated on the x-axis, and in the case shown in FIG. 3 the relative permeability ⁇ indicated on the y-axis decreases when the mechanical tension of the transmitter increases, i.e. when the pressure of the tyre increases.
• the x-axis indicates the time % and the y-axis indicates the prevailing pressure p as well as the relative permeability of the trans ⁇ mitter.
• the curve A is an illustrative example of the variation of the pressure p and the curve B illustrates the corresponding changes of the per ⁇ meability of the transmitter.
• On the permeability curve another curve C representing the permeability changes due to the self-oscillation frequency is superposed.
• the self-oscillation frequency in the illustrated example is higher at high pressure and lower at low pressure.
• the self-oscillation frequency of the transmitter thus is a measure of the existing press- ure condition in the tyre.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Fluid Pressure (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20365486

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (9)

• 1986
  • 1986-09-02 SE SE8603710A patent/SE454386B/sv not_active IP Right Cessation
• 1987
  • 1987-09-02 WO PCT/SE1987/000393 patent/WO1988001732A1/en unknown
  • 1987-09-02 ES ES8702548A patent/ES2005001A6/es not_active Expired
  • 1987-09-02 AU AU78781/87A patent/AU7878187A/en not_active Abandoned

Patent Citations (9)

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