| 摘要 |
<p>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 C1, C2, C3 and C4 from wheel speed sensors one at the left-hand front, right-hand front, left-hand rear and right-hand rear wheel positions respectively, comprising the step of calculating in normal driving an error value (DEL') where <MATH> the step of determining a correction factor (LAT), 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 <MATH> if the third or fourth deciding factor (MC3 or MC4) is greater than the central deciding factor (MPSD) then <MATH> or if none of the deciding factors (MC1, MC2, MC3 or MC4) is greater than the central deciding factor (MPSD) then <MATH> the step of calculating a corrected error value (DEL), and the step of operating a tyre warning indicator provided in the vehicle to indicate that at least one tyre is deflated when it is sensed that the magnitude of the corrected error value (DEL) is in the range 0.05 to 0.5, characterised by the step of determining vehicle related constants A, B, C for clockwise cornering and E, F G for anti-clockwise cornering by a setup procedure from sets of values (SV1-SVn n = 2,3,4...) of C1-C4 obtained by driving the vehicle respectively clockwise and anti-clockwise with its four tyres inflated to their normal scheduled pressure around a circle at a plurality of n constant speeds, and then calculating the corrected error value (DEL) by DEL = DEL' - DELCOR where DELCOR = (E x LAT)+(F x LAT<2>)+(G x LAT<3>) if the sign of the correction factor LAT is negative or DELCOR = (A x LAT)+(B x LAT<2>)+(C x LAT<3>) if the sign of the correction factor LAT is positive. <IMAGE></p> |
