Method for determining a wheel tire ground print
First Claim
Patent Images
1. A method for determining a footprint (Δ
- L) of a tire (3), corresponding to a length of contact of said tire (3) with the ground, of a vehicle equipped with a monitoring system that includes one wheel unit (4) for each tire (3), each wheel unit (4) comprising a microcontroller (14), a speed sensor (12′
), a transmitter (10), a reference clock (16) of the transmitter (10) configured to operate at a given frequency (F0), and at least one time control device for the system, where an actual frequency (F) output by said reference clock (16) is subject to variations (Δ
F) with respect to the given frequency (F0) when the wheel unit is within the footprint of the tire, the method comprising;
continuously measuring, by way of said time control device, for the variations (Δ
F) of the output frequency (F) of the reference clock (16) with respect to the given frequency (F0), as a function of time;
determining a time interval (TΔ
L) during which said variations (Δ
F) of the frequency of the reference clock (16) occur; and
on the basis of the rotation speed of the tire (3), deducing therefrom an angular contact range (Θ
) corresponding to the footprint (Δ
L) of the tire (3),wherein the time control device is a clock (13) of the microcontroller (14), which generates a signal representative of the variations (Δ
F) of the output frequency (F) of the reference clock (16) as a relative variation (Δ
F/F0) of the frequency (F) timed by the frequency of the clock (13) of the microcontroller (14), andwherein the method further comprises using the reference clock (16) of the transmitter to calibrate the clock (13) of the microcontroller (14) when the microcontroller (14) is in an angular range outside the contact angle (Θ
) corresponding to the footprint (Δ
L).
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Abstract
Method of determining the footprint of a tire on the ground, using devices already installed in standard production tires. Since the frequency of the transmitter clock present in a wheel unit is perturbed by mechanical vibrations when the tire contacts the ground, the frequency variations of the reference clock are representative of the value of the footprint. The method therefore includes determining the footprint on the ground of a tire of a wheel by measuring continuously, as a function of time, a signal representative of the variations in frequency of the reference clock supplied at the output of the time control device; determining a time interval during which the frequency variations of the reference clock occur; and, on the basis of the rotation speed of the tire, deducing therefrom an angular range of contact (Θ) corresponding to the footprint between the ends representing the ground contact length of the tire.
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Citations
2 Claims
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1. A method for determining a footprint (Δ
- L) of a tire (3), corresponding to a length of contact of said tire (3) with the ground, of a vehicle equipped with a monitoring system that includes one wheel unit (4) for each tire (3), each wheel unit (4) comprising a microcontroller (14), a speed sensor (12′
), a transmitter (10), a reference clock (16) of the transmitter (10) configured to operate at a given frequency (F0), and at least one time control device for the system, where an actual frequency (F) output by said reference clock (16) is subject to variations (Δ
F) with respect to the given frequency (F0) when the wheel unit is within the footprint of the tire, the method comprising;continuously measuring, by way of said time control device, for the variations (Δ
F) of the output frequency (F) of the reference clock (16) with respect to the given frequency (F0), as a function of time;determining a time interval (TΔ
L) during which said variations (Δ
F) of the frequency of the reference clock (16) occur; andon the basis of the rotation speed of the tire (3), deducing therefrom an angular contact range (Θ
) corresponding to the footprint (Δ
L) of the tire (3),wherein the time control device is a clock (13) of the microcontroller (14), which generates a signal representative of the variations (Δ
F) of the output frequency (F) of the reference clock (16) as a relative variation (Δ
F/F0) of the frequency (F) timed by the frequency of the clock (13) of the microcontroller (14), andwherein the method further comprises using the reference clock (16) of the transmitter to calibrate the clock (13) of the microcontroller (14) when the microcontroller (14) is in an angular range outside the contact angle (Θ
) corresponding to the footprint (Δ
L).
- L) of a tire (3), corresponding to a length of contact of said tire (3) with the ground, of a vehicle equipped with a monitoring system that includes one wheel unit (4) for each tire (3), each wheel unit (4) comprising a microcontroller (14), a speed sensor (12′
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2. A method for determining a footprint (Δ
- L) of a tire (3) of a wheel (1), corresponding to a length of contact of said tire (3) with the ground, of a vehicle equipped with a monitoring system that includes one wheel unit (4) for each tire (3), each wheel unit (4) comprising a microcontroller (14), a speed sensor (12′
), a transmitter (10), a reference clock (16) of the transmitter (10) configured to operate at a given frequency (F0), and at least one time control device for the system, where an actual frequency (F) output by said reference clock (16) is subject to variations (Δ
F) with respect to the given frequency (F0) when the wheel unit is within the footprint of the tire, the method comprising the following successive steps;measuring continuously, and recording (30, 60, 60′
), as a function of time, the frequency (F) at the output of the reference clock (16) and the variations (Δ
F) of the output frequency (F) with respect to the given frequency (F0);determining and recording the time interval (TΔ
L) during which said variations (Δ
F) of the frequency of the reference clock (16) occur;recording a rotation speed of the wheel (1) as a function of time based on an output of the speed sensor; using the recorded time interval (TΔ
L) of the variations of frequency (Δ
F) of the reference clock (16) and the recorded rotation speed of the wheel (1) to calculate and record an angular contact range (0) of the tire (3);defining a detection threshold (FMin) below which said frequency variations (Δ
F) are disregarded;if the frequency variations (Δ
F) are above the frequency threshold (FMin), calculating the footprint (Δ
L) on the basis of the contact angle (Θ
), the time interval (TΔ
L) and the speed of the wheel (1);defining boundaries (Δ
Lmin, Δ
Lmax) of the value of the footprint (Δ
L) beyond which the calculated value of the footprint (Δ
L) is not accepted;defining a frequency of calculation for determining the value of the footprint (Δ
L) of the tire (3); andrestarting the calculation at the frequency thus defined, wherein the time control device is a clock (13) of the microcontroller (14), which generates a signal representative of the variations (Δ
F) of the output frequency (F) of the reference clock (16) as a relative variation (Δ
F/F0) of the frequency (F) timed by the frequency of the clock (13) of the microcontroller (14), andwherein the method further comprises using the reference clock (16) of the transmitter to calibrate the clock (13) of the microcontroller (14) when the microcontroller (14) is located in an angular range outside the contact angle (Θ
) corresponding to the footprint (Δ
L).
- L) of a tire (3) of a wheel (1), corresponding to a length of contact of said tire (3) with the ground, of a vehicle equipped with a monitoring system that includes one wheel unit (4) for each tire (3), each wheel unit (4) comprising a microcontroller (14), a speed sensor (12′
Specification
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Current AssigneeContinental Automotive France (Continental AG), Continental Automotive GmbH (Continental AG)
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Original AssigneeContinental Automotive France (Continental AG), Continental Automotive GmbH (Continental AG)
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InventorsBenbouhout, Rachid, Bouthinon, Jean-Christophe
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Primary Examiner(s)Barbee, Manuel L
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Assistant Examiner(s)Nimox, Raymond L
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Application NumberUS15/101,086Publication NumberTime in Patent Office1,548 DaysField of SearchUS Class CurrentCPC Class CodesB60C 2019/004 Tyre sensors other than for...B60C 23/0408 transmitting the signals by...B60C 23/0447 Wheel or tyre mounted circuitsB60C 23/0474 Measurement control, e.g. s...B60C 23/0488 Movement sensor, e.g. for s...B60C 23/064 comprising tyre mounted def...G01B 21/02 for measuring length, width...
