EP0579446A1
Expired / Lapsed
EP
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Method of detecting a deflated tyre on a vehicle
Assignee: Sumitomo Rubber Industries Ltd
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Filing: 1993-07-07
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Granted: —
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Expires: 2013-07-07
Abstract
Abstract A method of detecting a deflated tyre on a vehicle by comparing the rolling radii of the tyres (1),(2),(3) and (4) by means of comparing angular velocity speed signals (5),(6),(7) and (8) from wheel speed sensors one at each wheel characterised by calculating an error value (DEL') where where C1, C2, C3 and C4 are angular velocity values for left-hand front, right-hand front, left-hand rear and right-hand rear wheels of the vehicle respectively, determining a correction factor (LAT), calculating a corrected error value (DEL) wherein in the case that the sign of the product LAT x A of the correction factor LAT and the vehicle related constant A is opposite to the sign of the error value DEL' then the corrected error value DEL is given by DEL = DEL' and in the case that the product LAT x A and the error value DEL' have the same sign but the product LAT x A is greater in absolute magnitude then the error value DEL' the corrected error value DEL is given by DEL = 0 otherwise the corrected error value DEL is given by DEL = DEL' - (LAT x A) and a tyre warning indicator is operated in the vehicle to indicate that at least one tyre is deflected when it is sensed that the magnitude of the corrected error value DEL is in the range 0.05 to 0.5.
Inventors
- 👤 David Jones
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 06:13
CPC Classifications
B; B60; B60C; B60C23/00; B60C23/06; B60C23/061
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
225 words
A method of detecting a deflated tyre on a vehicle by comparing the rolling radii of the tyres by means of comparing angular velocity speed signals from wheel speed sensors one at each wheel characterised by calculating an error value (DEL') where where C1, C2, C3 and C4 are angular velocity values for left-hand front, right-hand front, left-hand rear and right-hand rear wheels of the vehicle respectively, determining a correction factor (LAT), calculating a corrected error value (DEL) wherein in the case that the sign of the product LAT x A of the correction factor LAT and the vehicle related constant A is opposite to the sign of the error value DEL' then the corrected error value DEL is given by DEL = DEL' and in the case that the product LAT x A and the error value DEL' have the same sign but the product LAT x A is greater in absolute magnitude then the error value DEL' the corrected error value DEL is given by DEL = 0 otherwise the corrected error value DEL is given by DEL = DEL' - (LAT x A) and a tyre warning indicator is operated in the vehicle to indicate that at least one tyre is deflected when it is sensed that the magnitude of the corrected error value DEL is in the range 0.05 to 0.5.
Claim 2
Dependent Claim
195 words
A method of detecting a deflated tyre according to claim 1 characterised in that the correction factor (LAT) is selected by calculating from the four angular velocity values C1, C2, C3 and C4 respective first, second, third and fourth deciding factors (MC1, MC2, MC3, MC4) where MC1 = C1 MC2 = C2/[(C2+C4)/(C1+C3)] MC3 = C3/[(C3+C4)/(C1+C2)] MC4 = C4/[[(C2+C4)/(C1+C3)] x [(C3+C4)/(C1+C2)]], then summing the four deciding factors and multiplying this sum by a centralising constant (K) to give a central deciding factor (MPSD) and selecting the correction factor (LAT) as follows, if the first or second deciding factor (MC1 or MC2) is greater than the central deciding factor (MPSD) then LAT = 2 x (C3 - C4) x (C1 + C2 + C3 +C4), if the third or fourth deciding factor (MC3 or MC4) is greater than the central deciding factor (MPSD) then LAT = 2 x (C1 - C2) x (C1 + C2 + C3 + C4), or if none of the deciding factors (MC1, MC2, MC3 or MC4) is greater than the central deciding factor (MPSD) then LAT = (C1 + C3 - C2 - C4) x (C1 + C2 + C3 + C4).
Claim 3
Dependent Claim
27 words
A method of detecting a deflated tyre according to claim 2 characterised in that the centralising constant (K) has a value in the range 0.250125 to 0.250625.
Claim 4
Dependent Claim
23 words
A method of detecting a deflated tyre according to claim 2 characterised in that the centralising constant (K) has a value of 0.25025.
Claim 5
Dependent Claim
218 words
A method of detecting a deflated tyre according to claim 2, 3 or 4 characterised in that a deflation indicating factor (IMC1, IMC2, IMC3, IMC4) is calculated for each wheel respectively and the wheel having the numerically greatest deflation indicating factor is indicated as deflated, where the deflation indicating factors are calculated as follows: IMC1 = C1 , then if the first deciding factor (MC1) is greater than the central deciding factor (MPSD) then IMC2 = C2/[((C4/C3)/2) + 0.5] IMC3 = C3/[((C4/C2)/2) + 0.5] IMC4 = C4/[[((C4/C3)/2)+0.5] x [((C4/C2)/2)+0.5]]; if the second deciding factor (MC2) is greater than the central deciding factor (MPSD) then IMC2 = C2/[((C4/C3)/2) + 0.5] IMC3 = C3/[((C3/C1)/2) + 0.5] IMC4 = C4/[[((C4/C3)/2)+0.5] x [((C3/C1)/2)+0.5]]; if the third deciding factor (MC3) is greater than the central deciding factor (MPSD) then IMC2 = C2/[((C2/C1)/2) + 0.5] IMC3 = C3/[((C4/C2)/2) + 0.5] IMC4 = C4/[[((C2/C1)/2)+0.5] x [((C4/C2)/2)+0.5]]; if the fourth deciding factor (MC4) is greater than the central deciding factor (MPSD) then IMC2 = C2/[((C2/C1)/2) + 0.5] IMC3 = C3/[((C3/C1)/2) + 0.5] IMC4 = C4/[[((C2/C1)/2)+0.5] x [((C3/C1)/2)+0.5]]; or if none of the deciding factors (MC1, MC2, MC3, MC4) is greater than the central deciding (MPSD) factor then IMC2 = C2/[(((C2+C4)/(C1+C3))/2) + 0.5] IMC3 = C3/[(((C3+C4)/(C1+C2))/2) + 0.5] IMC4 = C4/[[(((C3+C4)/(C1+C2))/2) + 0.5] x [(((C2+C4)/C1+C3))/2) + 0.5]]
Claim 6
Independent Claim
44 words
A method of detecting a deflated tyre according to any of claims 1 to 5 characterised in that the tyre warning indicator is operated when it is sensed that the magnitude of the corrected error value (DEL) is in the range 0.1 to 0.3.
Claim 7
Independent Claim
33 words
A method of detecting a deflated tyre according to any of claims 1 to 6 characterised in that the value of the vehicle related constant (A) is in the range -2.0E-7 to +2.0E-7.
Claim 8
Independent Claim
28 words
A method of detecting a deflated tyre according to any of claims 1 to 6 characterised in that the value of the vehicle related constant (A) is -2.0E-7.
Claim 9
Independent Claim
28 words
A method of detecting a deflated tyre according to any of claims 1 to 6 characterised in that the value of the vehicle related constant (A) is -0.6E-7.
Claim 10
Independent Claim
28 words
A method of detecting a deflated tyre according to any of claims 1 to 6 characterised in that the value of the vehicle related constant (A) is +1.3E-7.
References Cited (Backward Citations)
EP0489562A1
Cited
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