EP0441600A2
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EP
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Method of detecting a deflated tyre on a vehicle
Assignee: Sumitomo Rubber Industries Ltd
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Filing: 1991-02-05
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Granted: —
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Expires: 2011-02-05
Abstract
Abstract A method of detecting a partially deflated pneumatic tyre on a vehicle having four tyres each mounted on a wheel comprising sensing the angular velocity of each wheel by providing for each wheel, a signal generator to provide a single signal or pulse for each turn of the wheel, characterised by selecting a first wheel and measuring the time for one rotation of that first wheel, after beginning said first measurement similarly measuring the times of rotation for each other wheel, storing the times for each of the wheels for at least three rotations of each wheel and averaging the times to produce an average angular velocity value for each wheel, processing the four signals in a processor unit which subtracts the sum of the signals from one pair of diagonally opposite wheels from the sum of the signals from the other pair of diagonally opposite wheels, sensing when the magnitude of the result is between 0.05% and 0.60% of the mean of the two sums and when it is operating a warning device to indicate a tyre is partially or completely deflated. The method may also compare the signal of each wheel in turn to the average of all four to determine which wheel is deflated.
Inventors
- 👤 John Charles Walker
- 👤 Lavinder Singh Rehal
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 10:54
CPC Classifications
B; B60; B60C; B60C23/00; B60C23/06; B60C23/061
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
183 words
A method of detecting a partially deflated pneumatic tyre on a vehicle having four tyres each mounted on a wheel comprising sensing the angular velocity of each wheel by providing for each wheel, a signal generator to provide a single signal or pulse for each turn of the wheel, characterised by selecting a first wheel and measuring the time for one rotation of that first wheel, after beginning said first measurement similarly measuring the times of rotation for each other wheel, storing the times for each of the wheels for at least three rotations of each wheel and averaging the times to produce an average angular velocity value for each wheel, processing the four signals in a processor unit which subtracts the sum of the signals from one pair of diagonally opposite wheels from the sum of the signals from the other pair of diagonally opposite wheels, sensing when the magnitude of the result is between 0.05% and 0.60% of the mean of the two sums and when it is operating a warning device to indicate a tyre is partially or completely deflated.
Claim 2
Dependent Claim
73 words
A method according to claim 1 characterised in that the processor unit also compares the signal for each of wheels in turn with the signals for each of the other wheels, senses when one of the said signals is different to the average of all four signals by more than 0.1% and in the event of this signal and the magnitude of the result being both in said ranges operating the warning device.
Claim 3
Dependent Claim
21 words
A method according to claim 1 or 2 characterised in that the times are each measured against a standard clock frequency.
Claim 4
Dependent Claim
20 words
A method according to claim 1, 2 or 3 characterised in that there is a separate clock for each wheel.
Claim 5
Dependent Claim
23 words
A method according to claim 3 or 4 characterised in that the clock is started at the first pulse for the wheel concerned.
Claim 6
Dependent Claim
25 words
A method according to claim 3 or 4 characterised in that the clock runs continuously and the time is taken each time a signal occurs.
Claim 7
Independent Claim
57 words
A method according to any one of claims 1 to 6 characterised in that for each wheel at least 3 successive average angular velocity values are stored and interpolation is used to calculate for each wheel the angular velocity at a chosen time, so that the angular velocities of all wheels are known for the same time.
Claim 8
Independent Claim
39 words
A method according to any one of claims 1 to 7 characterised in that the single signal is derived from a multi signal generator by ignoring intermediate signals between two successive signals from a pre-selected single signal generating segment.
Claim 9
Dependent Claim
45 words
A method according to claim 8 characterised in that the time of rotation for the first wheel is begun from a first pulse and the times of rotation for each other wheel are begun from the pulse for the respective wheel following said first pulse.
Claim 10
Independent Claim
54 words
A method according to any of claims 1 to 9 characterised in that 15 rotations of each wheel are taken, each set of 15 rotations is divided into three groups of 5 rotations each and the angular velocities of all four wheels are computed by interpolation to give the speeds at a predetermined time.
Claim 11
Dependent Claim
27 words
A method according to claim 10 characterised in that the interpolation is for the speeds at the start of timing of the fourth wheel to be timed.
Claim 12
Independent Claim
43 words
A method according to any one of claims 1 to 11 characterised by the processing unit repeating the two sensing operations and operating the warning device when at least two successive results each give an indication of a tyre subject to pressure loss.
Claim 13
Independent Claim
47 words
A method according to any one of claims 1 to 12 characterised by the processing unit also monitoring lateral acceleration signals for the vehicle and inhibiting the warning signal for vehicle lateral accelerations greater than a predetermined value averaged over at least 5 turns of each wheel.
Claim 14
Dependent Claim
13 words
A method according to claim 13 characterised in that the value is 0.06g.
Claim 15
Independent Claim
49 words
A method according to any one of claims 1 to 14 characterised by the processing unit itself calculating the lateral acceleration by comparison of the wheel angular velocity signals from side to side of the vehicle and the vehicle forward speed calculated from the mean of the angular velocities.
Claim 16
Independent Claim
68 words
A method according to any one of claims 1 to 15 characterised by the processing unit calculating the acceleration and deceleration of the vehicle in its direction of travel by monitoring the rate of change of the sum of the angular velocity of all four wheels with relation to time and inhibiting the pressure loss of warning system if the vehicle acceleration or deceleration exceeds a predetermined value.
Claim 17
Dependent Claim
14 words
A method according to claim 16 characterised in that the predetermined value is 0.03g.
Claim 18
Independent Claim
23 words
A method according to any one of claims 1 to 17 characterised in that the clock rate is changed at different vehicle speeds.
Claim 19
Independent Claim
51 words
A method of any one of claims 1 to 18 characterised by the processing unit, following receipt of a calibrate signal, measuring the angular velocities of all four wheels, determines calculation constants to allow for the rolling radius of each tyre at the time of calibration and subsequently using said constants.
Claim 20
Dependent Claim
37 words
A method according to claim 19 characterised by the calculation of constants being repeated at at least one higher speed to provide secondary constants allowing for changing in rolling radius of the vehicle tyres at said speeds.
References Cited (Backward Citations)
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