The present invention relates to a system for evaluating the state of a tire. More precisely, the invention relates to such a system furnished with a device for detecting the direction of rolling of a vehicle over this evaluation system.
Within the meaning of the present invention, a system for evaluating the state of a tire is for example, but not limitingly, a system making it possible to detect the wear of a tire, a system making it possible to detect the pressure of a tire, or by extension a system making it possible to measure the speed of a tire.
Thus, the invention also relates to a method for detecting the direction of rolling of a tire over a system according to the invention. It also relates to a method for detecting the speed of passage of a vehicle over a system according to the invention.
Numerous systems allowing the diagnosis of a vehicle are known. In respect of wear, it is thus possible to cite wear telltales present on tires, or manual devices for measuring the height of rubber remaining on a tire.
Concerning pressure measurement, it is possible to cite systems installed directly on the wheels of vehicles, which determine the pressure by means of a pressure sensor and which thereafter dispatch the information by radiofrequency to the vehicle's central electronics; off-board systems allowing the measurement of contact pressure of the tires at the ground level, or else manual manometers.
The present invention is aimed at providing a system, notably usable by vehicle fleet managers, which can be included in a more general system for diagnosis of the state of a vehicle and of its tires. However, none of the known systems currently allows cross-checking of various pieces of information relating to the vehicle and its tires.
A measurement system comprising a running bench intended to accommodate the passage of a vehicle is known from Document US 2009/0000370. It has however been found that, for large gauge vehicles, it was sometimes necessary to use two distinct running benches for each of the sides of the vehicles, and that such a system did not make it possible to identify, during a measurement, the side of the vehicle concerned in the said measurement.
The present invention is therefore aimed at remedying this drawback by proposing an improvement of existing vehicle diagnosis systems.
Thus, the invention proposes a system for evaluating the state of a tire, the system comprising a first housing laid on the ground, the said system comprising
Such a system thus makes it possible to measure various characteristics of a tire in a single pass, and also makes it possible to detect the direction of rolling of the vehicle over the system during this pass.
In an advantageous embodiment, the first and second sensors are positioned in the housing in such a way that the projection of their position on the plane upper face of the housing defines a line non-orthogonal to the direction of rolling of a vehicle over the housing.
In an advantageous embodiment, the first and/or the second sensor are included in the group comprising: an eddy-current-based wear sensor, a variable-reluctance wear sensor, a laser-based optical wear sensor, a local pressure or load sensor.
In an advantageous embodiment, the system furthermore comprises a tire presence detection device installed in the housing. In a preferential manner, this presence detection device uses a single input on the system control electronics.
In an advantageous embodiment the presence detection device comprises a sensitive element included in the group comprising: an accelerometer or any type of sensor sensitive to vibrations or to shocks, a magnetometer or any type of sensor sensitive to terrestrial magnetic field variation, a resistance wire extensometer, also called strain gauges or deformation gauges, a piezoelectric buzzer or any system using a piezoelectric material or a composite such as a piezo-electrical paint.
Alternatively, the tire presence detection device may consist of a leaktight cavity accommodating a fluid and of a pressure sensor installed so as to measure the pressure of the fluid in this cavity. The arrival of a tire over the housing causes an increase in pressure of the fluid in the cavity, detected by the pressure sensor. This signal can thereafter be used as indicator of the presence of a vehicle over the housing. In another example, it is possible to use a mechanical contact detector, implementing a flexible plate. This contact detector is positioned at an end of the cavity, and subjected to a motion of the fluid should the pressure in the cavity increase. This detector closes electrically when a vehicle is present over the housing.
In an advantageous embodiment, the system comprises a first group of sensors of the same type as the first sensor, and a second group of sensors of the same type as the second sensor, the sensors of the first group being positioned in such a way that their orthogonal projections on the plane upper surface of the housing form a first line, and the sensors of the second group being positioned in such a way that their orthogonal projections on the plane upper surface of the housing form a second line, and the first and second lines being distinct, and oriented in a direction not parallel to the direction of rolling of a vehicle over the housing. Preferentially, the two lines are orthogonal to the direction of rolling of a vehicle over the housing.
The use of a number of higher sensors makes it possible to guarantee that the measurements are performed during the passage of a vehicle over a housing, this being so whatever the size of the tires of the vehicle. Indeed, by positioning several sensors over the width of the housing, it is guaranteed that any tire passing over the housing will pass at least above a sensor of the first group and above a sensor of the second group. The number of sensors will therefore advantageously be chosen as a function of the dimensions of the housing and of the dimensions of the envisaged tires.
These sensors will preferably be positioned quincuncially. Quincunx is understood to mean a position according to which the orthogonal projections of the sensors of the first group are regularly distributed over a first line, the orthogonal projections of the sensors of the second group are regularly distributed over a second line, and the elements of the second line are offset by a half-spacing with respect to the elements of the first line, a spacing corresponding to the gap between two elements of the first line. This quincuncial positioning assists the effectiveness of the measurement system such as explained in the previous paragraph.
In an advantageous embodiment, the system comprises a second housing identical to the first, the first and second housings being positioned in such a way that during the passage of a vehicle, the tires situated on a first side of the vehicle roll over the first housing, and the tires situated on a second side of the vehicle roll over the second housing.
The use of such a system furnished with two housings is particularly advantageous for the evaluation of tires installed on large gauge vehicles, for example heavy goods vehicles. This typical case will subsequently be described in detail with the aid of the figures, notably
The invention also relates to a method for determining the direction of rolling of a vehicle over a system for evaluating the state of a tire according to the invention. This method comprises the following steps:
This method finds a particularly advantageous application in the case, mentioned previously, of an evaluation system comprising two housings. This case of application will subsequently be detailed with the aid of figures.
The invention also relates to a method for measuring the speed of a tire rolling an evaluation system according to the invention. This method comprises the following steps:
In an advantageous embodiment, the distance between the orthogonal projections is recorded in a memory linked to the system control electronics.
In another advantageous embodiment, the system according to the invention is furnished with radiofrequency communication means allowing the transmission of the measured data to a remote server. In this case, the distance between the orthogonal projections can be recorded in a database installed on a remote server, and the calculation of the speed can be performed by calculation means associated with the said database.
Other advantages and embodiments of the invention will become apparent with the nonlimiting detailed description of the figures in which:
a,
1
b,
1
c and 1d show an evaluation system exhibiting the drawbacks of the prior art, and
Each of the housings is identical to the housing 10 shown in
It furthermore comprises:
Furthermore, the electronics 110 is equipped with a tire 40 presence detection device 120 making it possible to activate the measurement system solely at the moment or a tire 40 presents itself over the system. In the case set forth in this example, the tire presence detection device 120 consists of a single sensor sensitive, for example, to the vibrations or shock waves propagating in the structure of the housing 10 when a tire 40 arrives over the said housing.
In a variant embodiment of the housings 20 and 30, this sensor for detecting presence of a tire is a sensor sensitive to the variation of the terrestrial magnetic field when a vehicle arrives over the measurement system.
In any event, in the example of
Thus, in the case of
Conversely, in the case of
In this case, the system not knowing the direction of rolling of the vehicle, it will not be able to determine to which side of the vehicle the tires measured by the two housings 20 and 30 belong. It will not therefore be possible to specify the side of the vehicle on which a possible maintenance operation should be programmed, for example, because of overly significant wear.
If it is imagined that the housings 20 and 30 of
Conversely, if a vehicle presents itself from the left of the measurement system 11, the measurement sensors 100 situated on the line a will be able to begin carrying out a measurement before the sensors situated on the line b.
Furthermore, in this example, the processing electronics 111 comprises means for determining the time elapsed between the start of the measurement on either of the two lines of sensors and the start of the measurement on the other line of sensors.
The distance between the line a and the line b being known, it is also possible to measure the speed of the tire by using the time elapsed between the start of the measurement by the line b and the start of the measurement by the line a. If appropriate, it suffices to apply the formula:
V=d/t
in which V is the speed of the tire whose wear is measured, d is the distance between the two lines of sensors a and b and t is the time elapsed between the start of the measurement by either of the lines of sensors and the start of the measurement by the other line of sensors.
Alternatively, it is possible to determine the time t by measuring the time elapsed between the end of the measurement by one of the lines of sensors and the end of the measurement by the other line of sensors.
The electronics 111 is furnished with threshold-based electronics making it possible to detect the crossing, by the signal, of a voltage threshold labelled at the positions 41 and 51 on the signals 31. It is therefore possible to label the direction of rolling by observing the order in which the output signals of adjacent sensors 100 each situated on two different lines cross the threshold 41.
Alternatively, it is possible to use the threshold 51, corresponding to the moment at which the tire whose wear is measured leaves the measurement zone situated on the housing 11, to reach the same conclusion.
In the case of
Furthermore, the time t elapsed between the passage of the solid-line signal through the threshold 41, or 51, and the passage of the dashed signal through the same threshold 41, or 51, corresponds to the time required for the tire to pass from sensor line a to sensor line b.
As explained previously, the gap between the two lines a and b being known, it is this time t which will have to be used to measure the speed of passage of the vehicle over the system.
Number | Date | Country | Kind |
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1462593 | Dec 2014 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2015/079460 | 12/11/2015 | WO | 00 |