FR3143758A1 - Unit and Module for detecting breakage of a substrate in an enclosure - Google Patents

Abstract

The present invention relates to a sensor unit (5) comprising a support block (50, 50') and at least one piezoelectric sensor (42), characterized in that said support block comprises at least a first housing (52) for housing said piezoelectric sensor and in that said support is able to cooperate with a guide (60) to be carried by said guide. Figure 11

Description

Unit and Module for detecting breakage of a substrate in an enclosure

The invention relates to a system for measuring the breakage of a substrate.

Prior art

The production of laminated glazing consists of assembling two sheets of glass with a polymer interlayer film such as PVB. The glazing is joined by passing it through an autoclave oven to undergo a step in which the glazing is subjected to temperature and pressure constraints. This step in the autoclave oven allows the polymerization of the polymer and therefore the joining of the glass sheets.

A disadvantage of this step is that the autoclave oven is, by definition, an enclosure in which it is not possible to see what is happening. However, the risks of breakage are real. Today, breakages in the autoclave are only observed visually at the exit of this step of the process. However, it is important to know at what point in the cycle breakages are most likely and their position on the rack. This spatio-temporal information coupled with temperature distribution measurements in the autoclave should allow us to better understand the origin of the breakages and to minimize them.

There is therefore a need for a device or system allowing the detection of breakage in such an autoclave oven enclosure.

The present invention aims to provide a system for measuring the breakage of a substrate which is reliable and precise in a hermetic enclosure.

For this purpose, the invention relates to a sensor unit comprising a support and at least one piezoelectric sensor, characterized in that said support comprises at least a first housing for housing said piezoelectric sensor and in that said support is capable of cooperating with a guide to be carried by said guide.

In one example, the bracket includes a second housing for housing another sensor.

According to one example, the first housing and/or the second housing are open.

According to one example, the sensor arranged in the second housing is a piezoelectric sensor.

In one example, the sensor arranged in the second housing is a temperature sensor.

The invention further relates to a sensor module characterized in that it comprises at least one sensor unit according to the invention and a guide, said guide being arranged to cooperate with the support of said unit in order to carry the latter.

According to one example, the support is pierced with at least one opening and the guide is a rod inserted into said opening.

In one example, the guide is a tube and the support has a section such that it fits into the tube.

In one example, the support has a section whose shape is identical to the section of the tube.

According to one example, the sensor module includes a plurality of sensor units.

The invention also relates to an enclosure in which substrates are subjected to temperature and pressure constraints, said enclosure comprising at least one easel supporting the substrates, in which said easel comprises at least one sensor module according to the invention.

In one example, each substrate is in contact with at least one guide.

According to one example, the easel comprises a plurality of sensor modules, said sensor modules being arranged to be aligned vertically and/or horizontally.

In one example, said horizontally aligned sensor modules are spaced apart so that at least one substrate fits between two sensor modules.

In one example, a substrate comprises two sheets of glass between which an interlayer film is placed.

Description of figures

Other features and advantages will clearly emerge from the description given below, for information purposes only and in no way limiting, with reference to the attached drawings, in which:

- there represents a view of an enclosure according to the invention;

- there represents a cross-sectional view of a substrate;

- THE and 4 represent a diagram of the acquisition module according to the invention;

- there represents a view of a sensor unit according to the invention;

- THE and 7 represent a first embodiment of the support block;

- THE to 10 represent a second embodiment of the support block;

- THE and 12 represent a bridge for an enclosure according to the invention;

- THE and 14 represent a variant of the sensor unit according to the invention;

Detailed description of the invention

The invention shown in the describes an enclosure 1 in which pressure and temperature constraints are applied. This enclosure is capable of accommodating at least one substrate 2 such as glazing. This glazing may be a single sheet of glass or comprise at least two sheets of glass 20 and an interlayer film 21 arranged between these two sheets as visible in the .

This at least one glazing is placed in the enclosure directly on the ground or via a support 3 such as an easel or any other possible support.

The enclosure 1 is provided with a system for detecting the breakage 4 of a substrate. This system for detecting the breakage 4 comprises an acquisition module 40. Such an acquisition module 40, visible in the , is used to retrieve data and temporarily store it in a memory unit 46 of said acquisition module. This acquisition module then comprises at least one sensor 42 connected to a controller 44.

This data from the acquisition module 40 is intended to be sent to a calculation unit UC. This calculation unit is used to retrieve this data and process it.

The sensor 42 of the detection system uses piezoelectric technology. Indeed, when the glass is subjected to constraints, variations in temperature and/or pressure, the stored energy is suddenly released. Part of the energy thus released is re-emitted in the form of an elastic wave, which propagates in the glass. The generated sound or ultrasonic noises can be detected using piezoelectric elements. These elements will convert the mechanical wave into a usable electrical signal.

The piezoelectric sensor is in the form of a pellet in direct or indirect contact with the surface of the glazing. The acquisition module 40 comprises a conversion unit 48 for converting the incoming signal coming from the sensor into representative data stored by the controller in the memory unit. This conversion unit 48 can be integrated into the controller 44.

The conversion unit 48, visible at the , then includes a differential amplification stage 481 to reject the common signal from its inputs to amplify only the differential component, a low-pass filter 482 with a cut-off frequency at 12Khz and an analog-to-digital converter 483.

The acquisition module 40 is capable of retrieving data from a plurality of sensors. For this, a first solution consists of having a conversion unit per sensor. Thus, the controller has as many inputs for the sensors as the number of sensors. A ten-channel controller will allow 10 sensors to be connected and a 16-channel controller will allow sixteen sensors to be connected. This possibility allows the monitoring of a plurality of windows.

In a second solution, the acquisition module comprises only one conversion unit, a multiplexer being arranged between the sensors and the controller, said controller then being equipped with a demultiplexer. The multiplexer and the demultiplexer are thus designed to operate at a frequency allowing the necessary data to be collected.

So, when a break occurs, the sound produced is captured by the piezoelectric sensor. The latter transcribes this sound into a voltage which is then converted into a value and then stored.

The data stored in the memory unit are suitable for use by a computing unit. To do this, the acquisition module is removed from the enclosure to be connected to a computing unit. This computing unit is then designed to retrieve this data and process it, i.e. compile and display it.

Alternatively, this monitoring of the glazing can be in real time. For this, the acquisition module is permanently connected to the calculation unit. This connection can be wired or wireless. In the latter case, the acquisition module includes a wireless communication unit. Preferably, this communication unit is located at the level of the enclosure and is connected by a wire to the acquisition module. Indeed, the pressure and temperature conditions of the furnace are constraints so that the furnace acts as a kind of shielded cage. To transmit data by radio, the communication unit is placed on the furnace but outside the pressurized and temperature-controlled enclosure. Thus, the acquisition module can transmit the data to the calculation unit directly.

For the power supply, two options are possible. The first option is applicable, in particular in the case where the acquisition module is connected to the calculation unit after the glazing has been removed from the oven. In this case, the acquisition module is powered by a battery. This battery is sized to allow the acquisition module to operate for a defined time. This time is defined as at least equal to the time the glazing is in the oven.

The second option is to have a mains power supply. This mains power supply requires running a cable into the enclosure to bring the power.

While this second option is advantageous because it allows for unlimited power, it may require modification of the oven to run the power cable(s) through the oven enclosure.

According to the invention, the piezoelectric sensor 42 is mounted on a support block 50 to form a sensor unit 5 visible to the . This support block consists of a block comprising at least one hole 52. This hole, whether through or not, is used to house said piezoelectric sensor. It is then understood that the support block 50 is in the form of a bar or profile, that is to say a part extending in length with a section, preferably constant. The hole extends in the support in a direction orthogonal to the direction of the length of the bar forming the support block.

This support block 50 is such that it is able to cooperate with a guide 60 or guide element so that this guide element can carry said support block. Preferably, the guide element is able to carry several support blocks.

In a first embodiment visible at the , the support block 50' comprises at least one through opening 54 and the guide element 60 comprises at least one rod 62 capable of being inserted into the opening of the support. Preferably, the support block 50' comprises two openings 54 and the guide element comprises two rods 62. This or these rods 62 may be of circular or ovoid section.

In a second embodiment visible at the , the guide element 60 is a tubular element 64. It then comprises a housing 65 in which said support block 50 can be inserted. More particularly, the support block 50 is arranged so that the direction in which the support is inserted is the same as that in which the support extends. For this, two solutions are possible.

The first solution is to have the support block 50 which has a shape identical to that of the section of the housing 65 as visible in the . Thus, if the guide element 60 is a tube of circular section then the support has a circular section, the diameter of the support being identical to the internal diameter of the tube.

A second solution is to have a section of the support block 50 which differs from that of the tube-shaped guide as visible in the . More particularly, it is then understood that the support block 50 has a section: shape and dimensions such that it fits into the tubular element 64. Thus, if the tubular element 64 has a tubular housing of circular section, the support block can have a square or rectangular section as long as it fits therein.

In both embodiments, the tubular element 64 is capable of carrying several support blocks and therefore several sensors as visible in the . In both of these embodiments, the tubular element 64 is made of a material of the metal or alloy or polymer type.

This tubular element 64 carrying the piezoelectric sensor support block(s) is cleverly used as an interlayer to support the glass sheet(s).

Indeed, the glass sheets forming the glazings are placed in the furnace on support elements or trestles 3. These trestles or support elements 3 comprise a structure from which rods extend as visible in FIGS. 11 and 12. These rods are used to support the glass sheets. These rods are the guide elements 60 carrying the support blocks 50 according to the invention.

As the glass sheets are in contact with the guides and the breakage of a glass causes a sound wave to propagate, the waves propagate until they reach the sensors by propagating through the guide and/or the support.

In an advantageous embodiment, the easel is equipped with several guide elements 60 fixed to the structure. These guide elements 60 or guides are arranged to be aligned along a line parallel to the floor of the furnace. These guide elements 60 are spaced apart to allow the insertion of the unassembled glazings in. The spacing between the guide elements 60 is arranged to allow the glass sheets of a glazing or several glazings to be placed therein. Thus, it is possible to have each glazing in contact with a guide or to have only certain glazings in contact with a guide. For example, with a stack of three glazings framed by two guides, two glazings are in contact with a guide while the central glazing is not in contact with any guide.

Furthermore, it is possible for the structure of the easel to include guide elements 60 aligned orthogonally to the plane of the floor of the furnace. This configuration thus makes it possible to have more piezoelectric sensors per glazing(s) and therefore to cover the surface of the glazing to allow localization of the breakage.

Indeed, as the breakage generates a sound wave that propagates, the amplitude of this wave attenuates depending on the distance traveled. With a single sensor for the glazing, it is possible to know if the breakage is close or far from the sensor but it is impossible to have an exact location. With a grid, it is possible to compile the values of the different sensors to determine the closest sensor.

Furthermore, since the glazing is made up of several sheets, the computing unit is able to detect which of the sheets has a breakage. To do this, an analysis of the amplitude is carried out. Indeed, if the breakage comes from the most distant sheet then the amplitude of the detected wave is slightly lower.

In a variant, the breakage is detected by the sensors of two guide elements 60. Indeed, as the glazings are installed between two guide elements 60, the sensors of the two guide elements 60 enclosing the glazing(s) are able to detect the wave generated following an impact. The localization is done by comparing the amplitude diagrams of the detected wave as a function of time of the different sensors to know which sensor detected the first and with what amplitude.

Of course, the higher the number of glazings between two guide elements 60, the more efficient the piezoelectric sensors must be, i.e. have a high acquisition frequency. Such an acquisition frequency makes it easier to determine the detector that first detects the sound wave, thus helping to locate the breakage.

In a variant, the support block 50, 50' of the sensor unit 5 further comprises at least one second housing 53 as visible in FIGS. 13 and 14. This second housing 53 is, preferably, arranged to be a through hole which extends in the support in a direction orthogonal to the direction of the length of the bar forming the support. This second housing 53 is used to place another sensor there. This sensor can be another piezoelectric sensor or a sensor of another type such as temperature.

In the case of a second piezoelectric sensor, the second housing 53 is symmetrical to the first housing 52. This second housing allows the second piezoelectric sensor to be turned towards another glazing or another stack of glazing. Thus, as each guide element is in contact with two glazings, stacks of glazing, then each guide can recover the data from two different glazings or stacks of glazing. Furthermore, for the same glazing or the same stack of glazing, the sensor(s) of two guides are used. This configuration makes it possible to detect a sound wave on either side of the glazing or the stack of glazing to thus facilitate the location of any breakage.

In another variant, the support block 50, 50' comprises an indexing means in the guide. For this, the indexing means comprises a body, preferably cylindrical, mounted on a spring in a housing. This housing may be the second housing or a third housing. The cylindrical body is arranged to cooperate with a cavity opening or not located on the guide. This allows, when the cylindrical body arrives opposite said cavity, said body to be inserted into said cavity thus fixing the position of said support in the guide. The guide comprises several cavities in order to be able to adjust the position of the support(s).

Of course, the present invention is not limited to the example illustrated but is susceptible to various variants and modifications which will appear to those skilled in the art.

Claims (15)

Sensor unit (5) comprising a support block (50, 50’) and at least one piezoelectric sensor (42), characterized in that said support block comprises at least one first housing (52) for housing said piezoelectric sensor and in that said support is capable of cooperating with a guide (60) to be carried by said guide. A sensor unit according to claim 1, wherein the support block comprises a second housing (54) for housing a further sensor therein. Sensor unit according to the preceding claim in which the first housing and/or the second housing are open-ended. Sensor unit according to one of claims 2 or 3, wherein the sensor arranged in the second housing is a piezoelectric sensor. Sensor unit according to one of claims 2 or 3, wherein the sensor arranged in the second housing is a temperature sensor. Sensor module characterized in that it comprises at least one sensor unit according to one of the preceding claims and a guide, said guide being arranged to cooperate with the support block of said unit in order to carry the latter. Sensor module according to the preceding claim, characterized in that the support is pierced with at least one opening and in that the guide is a rod inserted into said opening. Sensor module according to claim 6 characterized in that the guide is a tube and in that the support block has a section such that it fits into the tube. Module according to the preceding claim in which the support has a section whose shape is identical to the section of the tube. Module according to one of claims 6 to 9, in which it comprises a plurality of sensor units. Enclosure in which substrates are subjected to temperature and pressure constraints, said enclosure comprising at least one easel supporting the substrates, in which said easel comprises at least one sensor module according to one of claims 6 to 10. Enclosure according to the preceding claim in which each substrate is in contact with at least one guide. Enclosure according to one of claims 11 or 12, in which the easel comprises a plurality of sensor modules, said sensor modules being arranged to be aligned vertically and/or horizontally. Enclosure according to the preceding claim, in which said horizontally aligned sensor modules are spaced so that at least one substrate is inserted between two sensor modules. Enclosure according to one of claims 11 to 14, in which a substrate comprises two sheets of glass between which an interlayer film is placed.