Classifications

• • 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
• • 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
  • G01L17/005—Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies using a sensor contacting the exterior surface, e.g. for measuring deformation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M17/00—Testing of vehicles
  • G01M17/007—Wheeled or endless-tracked vehicles
  • G01M17/02—Tyres

Definitions

• This invention relates to a method and apparatus for tyre pressure determination.
• vibration inducing means in the form of a hammer is used to produce an impact with a tire to which is attached vibration detecting means in the form of an accelerometer which is secured to the tread of the tyre by double sided tape.
• Vibration measuring means is connected to the accelerometer, and is in the form of a computer frequency analyser (apparently a personal computer, judging from the drawing) .
• Tire pressure is determined by the frequency analyser.
• Such an analysis is based on the fact that the accelerometer measures radial acceleration and does so at "the best location" which is "the tread area” .
• the frequency analyser correlates vibration frequency peaks to tire pressure.
• an object of the present invention is to provide a method and apparatus for tire pressure determination offering improvements in relation to one or more of the matters discussed above in relation to the US 321 specification, or indeed generally.
• Further alternatives and more specific objects of the embodiments of the invention include provision of means for direct tire pressure determination which is conveniently applicable at times of tire inflation, and to provide a method and apparatus particularly applicable to tire pressure measurement with a tire off-vehicle, for example such that the measurement can conveniently be made while the tire is on a tire changer, during inflation and without halting the inflation process.
• a tyre is subjected to energy input and generates a corresponding energy waveform output and the waveform is analysed o determine tyre pressure.
• the energy input to the tyre is by means of a vibrational or acoustic input and the generation of the corresponding energy waveform output from the tyre is effected by means of a piezo-electric cable transducer, and the analysis of tyre pressure is carried out by reference to the waveform generated by the cable.
• the embodiments employ a mechanical impact device for energy input to the tyre, this being achieved utilising a convex-curved impact device associated with means for controlling the extent of the energy input to the tyre, whereby consistency of input can be achieved as a basis for a systematic approach to correlation and calibration of the output waveform data with respect to tyre pressure.
• the transducer for generation of the energy waveform from the tyre is a piezo- electric cable. The cable is mounted in physical contact with the tyre sidewall, for example by means of a mechanical holding device.
• the piezo-cable produces a particularly satisfactory and characteristic voltage waveform output which can be analysed on a frequency shift basis or on a time-base shift basis for calculation of the corresponding tyre pressure.
• Fig 1 shows a flow diagram illustrating the energy input by a hammer or ball device to the tyre and/or rim assembly, the piezo-cable taped to the tyre or rim producing a voltage which is analysed for dominant peaks and by reference to frequency and/or time domain shifts the apparatus is calibrated numerically in tyre pressure;
• Fig 2 shows plots of frequency against pressure for a range of identified automotive tyres, the frequencies plotted being those of the dominant peak obtained from a transducer connected to the tyre;
• a method 10 of tyre pressure determination comprises subjecting a tyre to energy input by an impact device providing mechanical impact with a tyre or with its associated wheel and/or rim.
• a controllable energy input device 12 which may be in the form of a constant height or angle hammer device 14 or a constant height ball bearing device 16, both of which are, in use, disposed so that the impact object (the hammer or the ball bearing) falls on the tyre or the wheel/rim assembly 18.
• a corresponding energy waveform output from the tyre is provided by means of electrical transducer means constituted by a length of piezo-electric cable
• the piezo-electric cable 20 is connected to voltage analysis means 22 which is adapted to determine tyre pressure by reference to the waveform generated by the piezo-electric cable.
• Voltage analysis means 22 performs the step 24 of identifying frequency and/or time domain shifts of the dominant peaks in the electromotive force (emf) generated by the piezo-electric cable.
• the system is calibrated, as shown at step 26, numerically in terms of tyre pressure. This is achieved on the basis of frequency calibration against known tyre pressure data.
• the method 10 comprises a controllable energy input 12 using the hammer device 14 or a ball bearing device 16 to apply an energy input to the tyre or wheel/rim assembly 18 in contact with which is taped the piezo-electric cable 20 which produces a signal voltage which is processed by analysis means 22 which identifies frequency or time domain shifts with respect to tyre pressure and is calibrated in suitable units such as pounds per square inch or bars.
• the wheel and tyre assembly 18 was attached to a wheel balancer (not shown) , and a length of piezo-cable 20 was attached to the tyre rim with adhesive tape.
• the piezo-cable was then electrically connected to a storage oscilloscope and the tyre was subjected to energy input by means of an impact with a small ball peen hammer (14) which was caused to make impact with the tyre by means of a pivoting fall from a predetermined height - see controllable energy input device 12 of Fig 1.
• the hammer may be as in Fig 1 of the US 321 reference but preferably with a convex hammerhead.
• the method 10 of Fig 1 is embodied in commercial practice by means of the energy input device 12 (in a suitable practical format such as a constant height/ angle hammer adapted to apply a controllable or generally constant level of energy input to the tyre or wheel/rim assembly.
• a power-operated impact device may be provided such as a solenoid- operated hammer adapted to generate continuously- repeated hammer strokes (such as are used in a bell- sounding mechanism) which can be readily mounted in relation to a vehicle wheel or rim or tyre, for example by magnetic or adhesive means.
• a battery or cable power supply mechanism is provided for the solenoid device.
• Other mechanical equivalents and related mechanisms are readily devised by the person skilled in the art.
• the length of piezo-cable 20 is provided with mechanical or adhesive means for attachment to the wheel and/or rim and/or tyre and likewise is connected to the voltage analysis means 22.
• This latter equipment may comprise a PC-based software system employing algorithmic analysis for identification of the frequency and/or time domain shifts of the dominant peaks in the emf output of piezo-electric cable 20.
• the application of repeated impacts at a generally constant energy level and generally constant intervals enables the dominant peaks to be readily monitored, and this can then be easily done during the tyre inflation process in order to monitor the rising pressure.
• the person skilled in the art is well able to design modifications and supplemental technical features for the system described above on the basis of the above-identified requirement to identify dominant peaks in a system calibrated in terms of numerical tyre pressure against frequency and/or time domain shifts.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Measuring Fluid Pressure (AREA)
• Tires In General (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=10812421

Family Applications (1)

Country Status (8)

Families Citing this family (11)

Family Cites Families (8)

• 1997
  • 1997-05-17 GB GBGB9709962.6A patent/GB9709962D0/en active Pending
• 1998
  • 1998-05-15 AU AU74383/98A patent/AU732281B2/en not_active Ceased
  • 1998-05-15 EP EP98921588A patent/EP0981726A1/en not_active Withdrawn
  • 1998-05-15 CA CA002289532A patent/CA2289532A1/en not_active Abandoned
  • 1998-05-15 KR KR1019997010605A patent/KR20010012644A/ko not_active Application Discontinuation
  • 1998-05-15 GB GB9810404A patent/GB2325303B/en not_active Expired - Fee Related
  • 1998-05-15 JP JP55007598A patent/JP2001527650A/ja active Pending
  • 1998-05-15 WO PCT/GB1998/001301 patent/WO1998053289A1/en not_active Application Discontinuation
  • 1998-05-15 CN CN98805207A patent/CN1256753A/zh active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events