Method of detecting a deflated tire on a vehicle
First Claim
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1. A method of detecting a deflated tire on a vehicle comprising the steps of:
- rotating each tire of the vehicle;
providing one wheel speed sensor for each of the tires;
detecting the angular velocity speed of the tires by the wheel speed sensors;
comparing the rolling radii of the tires by means of comparing angular velocity speed signals from wheel speed sensors characterized by calculating an error value (DEL'"'"') where ##EQU3## 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) where
space="preserve" listing-type="equation">DEL=DEL'"'"'-LAT×
Awherein A is a vehicle related constant, andoperating a tire warning indicator provided in the vehicle to indicate that at least one tire is deflated when the magnitude of the corrected error value (DEL) is sensed in the range 0.05 to 0.5, whereinthe correction factor (LAT) is selected by calculating from the angular velocity values C1, C2, C3 and C4 respective first, second, third and fourth deciding factors (MC1, MC2, MC3, and MC4) where
space="preserve" listing-type="equation">MC1=C1
space="preserve" listing-type="equation">MC2=C2/ (C2+C4)/(C1+C3)!
space="preserve" listing-type="equation">MC3=C3/ (C3+C4)/(C1+C2)!
space="preserve" listing-type="equation">MC4=C4/ (C2+C4)/(C1+C3)!×
(C3+C4)/(C1+C2)!!,then summing the first, second, third and fourth deciding factors and multiplying this sum by a centralizing 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
space="preserve" listing-type="equation">LAT=2×
(C3-C4)×
(C1+C2+C3+C4),if the third or fourth deciding factor (MC3 or MC4) is greater than the central deciding factor (MPSD) then
space="preserve" listing-type="equation">LAT=2×
(C1-C2)×
(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
space="preserve" listing-type="equation">LAT=(C1+C3-C2-C4)×
(C1+C2+C3+C4).
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Abstract
A method of detecting a deflated tire on a vehicle by rotating each tire of the vehicle, providing one wheel speed sensor for each of the tires, detecting the angular velocity speed of the tires by the wheel speed sensors, comparing the rolling radii of the tires by means of comparing angular velocity speed signals from wheel speed sensors characterized by calculating an error value (DEL'"'"') where
DEL'"'"'= (C1+C4)/2-(C2+C3)/2!×100/(C1+C2+C3+C4)/4
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) where
DEL=DEL'"'"'-LAT×A
wherein A is a vehicle related constant, and operating a tire warning indicator provided in the vehicle to indicate that at least one tire is deflated when the magnitude of the corrected error value (DEL) is sensed in the range of 0.05 to 0.5.
11 Citations
17 Claims
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1. A method of detecting a deflated tire on a vehicle comprising the steps of:
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rotating each tire of the vehicle; providing one wheel speed sensor for each of the tires; detecting the angular velocity speed of the tires by the wheel speed sensors; comparing the rolling radii of the tires by means of comparing angular velocity speed signals from wheel speed sensors characterized by calculating an error value (DEL'"'"') where ##EQU3## 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) where
space="preserve" listing-type="equation">DEL=DEL'"'"'-LAT×
Awherein A is a vehicle related constant, and operating a tire warning indicator provided in the vehicle to indicate that at least one tire is deflated when the magnitude of the corrected error value (DEL) is sensed in the range 0.05 to 0.5, wherein the correction factor (LAT) is selected by calculating from the angular velocity values C1, C2, C3 and C4 respective first, second, third and fourth deciding factors (MC1, MC2, MC3, and MC4) where
space="preserve" listing-type="equation">MC1=C1
space="preserve" listing-type="equation">MC2=C2/ (C2+C4)/(C1+C3)!
space="preserve" listing-type="equation">MC3=C3/ (C3+C4)/(C1+C2)!
space="preserve" listing-type="equation">MC4=C4/ (C2+C4)/(C1+C3)!×
(C3+C4)/(C1+C2)!!,then summing the first, second, third and fourth deciding factors and multiplying this sum by a centralizing 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
space="preserve" listing-type="equation">LAT=2×
(C3-C4)×
(C1+C2+C3+C4),if the third or fourth deciding factor (MC3 or MC4) is greater than the central deciding factor (MPSD) then
space="preserve" listing-type="equation">LAT=2×
(C1-C2)×
(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
space="preserve" listing-type="equation">LAT=(C1+C3-C2-C4)×
(C1+C2+C3+C4). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A deflated tire detector comprising:
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a plurality of speed sensors each provided for a corresponding tire of a plurality of tires on a vehicle, each of said speed sensors outputting an angular velocity of said corresponding tire; means for comparing rolling radii of said tires including means for calculating an error signal (DEL'"'"') where
space="preserve" listing-type="equation">DEL'"'"'= (C1+C4)/2-(C2+C3)/2!×
100/(C1+C2+C3+C4)/4where C1, C2, C3 and C4 are angular velocity output by said speed sensors for left-hand front, right-hand front, left-hand rear and right-hand rear tires of the vehicle respectively, means for determining a correction factor (LAT), means for determining a corrected error signal (DEL) where
space="preserve" listing-type="equation">DEL=DEL'"'"'-(LAT×
A)where A is a vehicle related constant, means for determining when a magnitude of said corrected error signal (DEL) is between 0.05 and 0.5 and for outputting a warning signal in response thereto; and a warning indicator, receiving said warning signal and providing a warning in accordance therewith, wherein said means for determining said correction factor (LAT) includes; means for 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
space="preserve" listing-type="equation">MC1=C1
space="preserve" listing-type="equation">MC2=C2/ (C2+C4)/(C1+C3)!
space="preserve" listing-type="equation">MC3=C3/ (C3+C4)/(C1+C2)!
space="preserve" listing-type="equation">MC4=C4/ (C2+C4)/(C1+C3)!×
(C3+C4)/(C1+C2)!!;means for summing the four deciding factors and outputting a sum; means for multiplying said sum by a centralizing constant K to give a central deciding factor (MPSD); and means for 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
space="preserve" listing-type="equation">LAT=2×
(C3-C4)×
(C1+C2+C3+C4),if the third or fourth deciding factor (MC3 or MC4) is greater than the central deciding factor (MPSD) then
space="preserve" listing-type="equation">LAT=2×
(C1-C2)×
(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
space="preserve" listing-type="equation">LAT=(C1+C3-C2-C4)×
(C1+C2+C3+C4). - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification
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Current AssigneeSumitomo Rubber Industries Limited
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Original AssigneeSumitomo Rubber Industries Limited
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InventorsJones, David
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Primary Examiner(s)Hofsass, Jeffery A.
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Assistant Examiner(s)Pope, Daryl C.
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Application NumberUS08/040,449Time in Patent Office2,294 DaysField of Search340/442, 340/444, 73/146US Class Current340/442CPC Class CodesB60C 23/061 by monitoring wheel speed m...
