Strategy for returning to service a wheel unit declared to have become detached in a motor vehicle tyre pressure monitoring system TPMS

Patent metadata

Field	Value
Publication number	US-11440359-B2
Application number	US-201716323598-A
Country	US
Kind code	B2
Filing date	Aug 25, 2017
Priority date	Aug 30, 2016
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

A method and TPMS system including a central unit and wheel units. Each wheel unit including a pressure sensor, regularly transmitting pressure and radial acceleration measurements to the central unit. The latter used to calculate a detachment parameter for the wheel unit. A test module determines whether each wheel unit is in a detached or operational state. A return-to-service module toggles the state of a wheel unit from the detached to the operational state if: since the wheel unit was declared detached, a pressure less than or equal to a reference atmospheric pressure is measured while the vehicle was at rest, and if after this rest, at least one of: the detachment parameter has not attained a nominal detachment threshold in a first movement time; an attachment index corresponding to a particular shape of a measurement signal of the wheel unit has been detected under specific evaluation conditions, occurs.

First claim

The invention claimed is:

1. A tire pressure monitoring system (TPMS) for checking tire pressure of an automotive vehicle, the TPMS system comprising:
a central unit; and
at least one wheel unit,
each of the at least one wheel unit comprising a pressure sensor and an emitter to allow pressure check transmissions from the at least one wheel unit to the central unit taking place at a first frequency and each comprising pressure measurements of the tire and measurements used to calculate a detachment parameter for the at least one wheel unit,
a test module configured to determine whether each of the at least one wheel unit is in a detached state or in an operational state, the at least one wheel unit being declared detached if the detachment parameter is greater than or equal to a predetermined nominal threshold of detachment; and

a return-to-service module configured to, when the at least one wheel unit has been detected as being in the detached state, toggle a state of the at least one wheel unit from the detached state to the operational state if and only if the following two conditions are fulfilled:
a first condition according to which, since the at least one wheel unit was declared detached, a pressure less than or equal to a reference atmospheric pressure has been measured while the vehicle was at rest,
a second condition according to which, after this rest, at least one of the following two criteria is satisfied:
the detachment parameter has not attained the nominal detachment threshold in a first movement time;
an attachment index is detected under specific evaluation conditions, the attachment index being that a measurement signal of the at least one wheel unit exhibits a particular shape representative of an attached state of the wheel unit.

2. The TPMS system as claimed in claim 1 , in which each wheel unit comprises a radial accelerometer, wherein the detachment parameter for each wheel unit is a percentage of measured negative radial accelerations, calculated over a sliding window of measurements of radial acceleration based on a last radial acceleration measurement.

3. The TPMS system as claimed in claim 1 , in which each of the at least one wheel unit comprises a radial accelerometer and is fixed on a rim or on a valve of a respective tire, wherein:
the measurement signal used to evaluate the attachment index is a radial acceleration signal resulting from measurements performed by the radial accelerometer;
a particular shape representative of the attached state is a sinusoid of amplitude lying between 0.7 g and 1.3 g;
and the specific evaluation conditions are that the vehicle is in motion.

4. The TPMS system as claimed in claim 1 , in which each of the at least one wheel unit comprises a radial accelerometer and is fixed inside a tread of a respective tire, wherein:
the measurement signal used to evaluate the attachment index is a radial acceleration signal resulting from measurements performed by the radial accelerometer,
a particular shape representative of the attached state is a substantially periodic presence of troughs corresponding to an imprint of the tire on the ground, which troughs have a maximum width T FTP and a periodicity T 360° exhibiting a ratio T FTP /T 360° lying between 4% and 10%,
and the specific evaluation conditions are that the radial acceleration is less than or equal to 4 g.

5. The TPMS system as claimed in claim 1 , further comprising, for each of the at least one wheel unit:
a state flag making it possible to record the detached state or the operational state of the at least one wheel unit, and
a pressure flag P 0 making it possible to record an item of information according to which a pressure less than or equal to the reference atmospheric pressure has been measured by the wheel unit.

6. The TPMS system as claimed in claim 1 , further comprising a diagnosis module configured to:
calculate one or more level(s) of damage sustained by the at least one wheel unit declared detached, which is(are) chosen from among: a cumulative movement time which has elapsed since the at least one wheel unit was declared detached; a number of high-intensity shocks recorded for the at least one wheel unit since it was declared detached, a high-intensity shock being defined by a derivative of order 3 of a position of the at least one wheel unit which, in absolute value, is greater than or equal to 500 g/ms;
compare each calculated level of damage with a corresponding predetermined threshold of damage.

7. The TPMS system as claimed in claim 6 , wherein the return-to-service module of the TPMS system is moreover configured to, when the at least one wheel unit has been detected as being in the detached state, toggle the state of at least one the wheel unit from the detached state to the operational state if and only if, in addition to the first condition and the second condition, a third condition is also fulfilled, the third condition being that each calculated level of damage is less than or equal to the corresponding threshold of damage.

8. The system as claimed in claim 6 , wherein the diagnosis module is configured to, moreover, command a modification of a sampling of an acceleration of the at least one a wheel unit declared detached so as to increase a frequency of the measurements of radial acceleration of the detached wheel unit so long as the vehicle is in motion.

9. The TPMS system as claimed in claim 1 , wherein:
each of the at least one wheel unit comprises at least three counters for synchronizing operations of a microcontroller of the at least one wheel unit, these counters imposing different recurrences,
the return-to-service module is configured to:
trigger a first counter imposing a slowest recurrence when, the at least one wheel unit having been declared detached, the vehicle is in motion and no pressure less than or equal to the reference atmospheric pressure has been measured,
trigger a second counter imposing a fastest recurrence when, the at least one wheel unit having been declared detached, the vehicle is not in motion and a pressure less than or equal to the reference atmospheric pressure has been measured,
trigger a third counter imposing an intermediate recurrence when, the at least one wheel unit having been declared detached, the vehicle is not in motion and no pressure less than or equal to the reference atmospheric pressure has been measured.

10. The TPMS system as claimed in claim 1 , wherein the reference atmospheric pressure is equal to 1.1 bar.

11. A method for returning to service a previously detached wheel unit, in a tire pressure monitoring system (TPMS) for checking a tire pressure of tires of an automotive vehicle comprising at least one wheel unit which can be in an operational state or in a detached state, a wheel unit of the at least one wheel unit being declared detached when a detachment parameter is greater than or equal to a predetermined nominal threshold of detachment,
wherein a state of the at least one wheel unit previously declared detached is toggled from the detached state to the operational state if and only if the following two conditions are fulfilled:
a first condition according to which, since the at least one wheel unit was declared detached, a pressure less than or equal to a reference atmospheric pressure has been measured by the at least one wheel unit while the vehicle was at rest,
a second condition according to which, after this rest, at least one of the following two criteria is satisfied:
the detachment parameter has not attained the nominal detachment threshold in a first movement time;
an attachment index is detected under specific evaluation conditions, the attachment ind

Assignees

• Continental Automotive France
• Continental Automotive Gmbh

Inventors

• Guinart Nicolas
• Fudulea Olivier

Classifications

• B60C23/0481 Primary

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