METHOD FOR LEAKAGE TESTING OF A DOUBLE-WALLED MOTOR VEHICLE PLATE USING ULTRASONIC SENSORS

Description

[0001] The invention relates to the general field of testing the tightness of a bonded assembly of motor vehicle parts.

[0002] More particularly, it relates to a device for controlling the tightness of a motor vehicle body panel consisting of two plastic walls bonded together. Such a panel may be a rear (tailgate) or side (door), front (hood) opening or an aerodynamic spoiler.

[0003] At present, for example, motor vehicle tailgates most often comprise a box, forming the internal wall of the panel, composed of a lower part, an upper part, as well as one or more body skins covering the parts of the box, which form the external wall of the panel. The assembly composed of the box and the body skin(s) is called a tailgate panel.

[0004] Generally, said at least one body skin is attached by gluing to the part of the box concerned: the skin and the part of the box each comprise for this purpose a continuous gluing track facing each other. The presence of the glue not only makes it possible to assemble the body skin to the part of the box, but also forms a seal between these two elements, and therefore the panel.

[0005] Once the body skin has been added and glued to the box section, it is necessary to check the tightness of such an assembly, and therefore the integrity of the seal formed by the glue joint. Here, integrity means the ability of the seal to ensure its sealing function. A reduction in integrity, or lack of sealing, can have different causes, such as a damaged or poorly positioned seal on the gluing track, poor positioning of the skin on the box section, insufficient application of the skin to the box section, etc.

[0006] To check the integrity of the seal formed by the glue joint, the assembly is generally pressurized with air under a clamping bell followed by detection of a possible pressure differential between, on the one hand, the volume located between the part of the box and the body skin thus assembled and, on the other hand, the exterior of the structure. Such a differential indicates a sealing defect, or loss of integrity, of the seal formed by the glue joint. To locate the defect, it is also possible to apply an air leak indicator product along the glue joint.

[0007] WO2008 / 152667 A1 describes a method and a device for detecting sound noises inside a vehicle generated by emissions from an air jet around the vehicle to check the integrity of the vehicle's seals. EP1988379 A2, DE102007046463 A1 and EP1450150 A2 describe similar devices. WO2007 / 068941 describes a device for checking the integrity of an adhesive seal between a bodywork and a windshield of a vehicle using an ultrasonic transmitter placed inside the vehicle and a detector outside the vehicle.

[0008] The control equipment mentioned above has many disadvantages.

[0009] Firstly, it is particularly imposing in terms of weight and volume due to its operation under air pressure.

[0010] Furthermore, its implementation and use is long and difficult for an operator, which makes it costly and incompatible with more systematic production control than statistical sampling, and even more so with unit control (100%).

[0011] Finally, due to the need to create overpressure inside the assembled part, the forces applied by the clamping bell are particularly high, which damages the part and makes it unusable on the vehicle. The clamping forces also have the consequence of damaging the control means itself, particularly at the level of the bell seals.

[0012] The invention aims in particular to provide a method for checking the tightness of a motor vehicle panel with double bonded walls, such as the aforementioned tailgate, which is less bulky, faster and easier to use, does not damage it, while being reliable.

[0013] To this end, the invention relates to a method for checking the integrity of a glue joint to be checked connecting a part of a bodywork box and a bodywork skin, defining between them an interior volume to be checked, characterized in that it includes the following steps, performed in this order: providing at least one ultrasonic detection device in the interior volume; emitting a directional jet of pressurized air opposite a predetermined area of ​​the glue joint; recording a noise level detected by the ultrasonic detection device in the interior volume; and determining an integrity defect in the glue joint according to the recorded noise level.

[0014] The invention therefore makes it possible, using simple and compact means, such as an air jet nozzle and microphones for example, to detect a reduction in integrity in the glue joint by recording the noise level in the interior volume emitted by the air from the directional jet having passed through the defect in the glue joint. Indeed, if the noise level recorded in the interior volume due to the application of the air jet opposite a predetermined area of ​​the glue joint is sufficiently high, it signals a defect in this area of ​​the glue joint.

[0015] The method proposed by the invention is both simpler and involves less bulky and easier-to-use equipment than pressurizing the assembly followed by detecting a possible pressure differential between, on the one hand, the volume located between the part of the box and the bodywork skin thus assembled and, on the other hand, the exterior of the structure. The detection of a noise level is also more reliable than the use of an air leak indicator product, and can also be easily automated. The equipment necessary to implement the control method according to the invention is without direct contact with the part and therefore does not involve any damage to the assembly to be controlled.

[0016] Furthermore, it was discovered that the noise level detected inside the interior volume of the assembly was greater due to the emission of a directional jet of pressurized air opposite a defect in the adhesive joint, rather than due to the simple emission of ultrasound by an ultrasound transmitter which would be located opposite such a defect.

[0017] Indeed, the forced passage of air from the jet through the bonding defect, generally a small orifice, produces high amplitude ultrasound like a whistle, under the mechanical effect of the pressure of the jet. In addition, the application of the jet makes it possible to detect certain small orifices in the glue joint which, partially or totally closed by the assembly pressure exerted by the rest of the joint, would not have been crossed by ultrasound emitted by a simple ultrasound transmitter. Indeed, the pressure of the jet makes it possible to open these orifices and thus to reveal them.

[0018] Thus, the method according to the invention makes it possible to detect differences in accentuated and large amplitude noise levels between a zone of the glue joint without defects and a zone of the glue joint with defects, making the detection method all the more reliable.

[0019] Preferably, the control method further comprises a step of comparing the recorded noise level with a reference noise level; and in which an integrity defect in the glue joint is determined if the recorded noise level is different from the reference noise level.

[0020] Indeed, given the complex shapes that the assemblies of box parts and body skin can take once assembled and the reverberation effects thus created within the interior volume of the assembly, the noise levels recorded there, even in the absence of defects, differ significantly depending on the areas of the glue joint to be checked. It is therefore preferable to compare the noise level recorded on a part to be checked with a reference noise level corresponding to a compliant part or an average taken on a batch of compliant parts.

[0021] Advantageously, before the step of arranging at least one ultrasound detection device in the interior volume, the following steps are carried out: provision of at least one ultrasound detection device in the interior volume, called the reference volume, defined by a bodywork box portion and a bodywork skin connected by an adhesive joint not comprising a sealing defect, called the reference adhesive joint; emission of a directional jet of air under pressure opposite a predetermined zone of the reference adhesive joint; detection of the noise level in the interior reference volume; and recording of the noise level thus detected.

[0022] This allows a comparison of noise levels to be made between a set of bodywork box parts and bodywork skin connected by a glue joint to be checked with an identical set, known as a reference set, which is known to be free of defects, or an average carried out on a batch of compliant parts.

[0023] Preferably, the predetermined area of ​​the reference glue joint corresponds to the same predetermined area of ​​the glue joint to be controlled.

[0024] Indeed, given that the noise levels recorded in the interior volume of the assembly vary from one area of ​​the glue joint to another, it is preferable to compare two by two the noise levels recorded for the same predetermined areas of the reference glue joint and the glue joint to be controlled.

[0025] In order to control multiple areas of the glue joint, the transmission and recording steps are performed for a plurality of predetermined areas of the glue joint.

[0026] Preferably, in order to control the entire glue joint, the predetermined areas are uniformly distributed along the glue joint.

[0027] Preferably, in order to more precisely control the entire glue joint, the predetermined areas are contiguous and the union of the predetermined areas includes substantially the entire perimeter of the glue joint.

[0028] In order to promote noise emissions in the interior volume and thus improve its detection in the interior volume of the assembly, the air jet is emitted at the glue joint.

[0029] To further improve noise detection, the air jet is emitted in the immediate vicinity of the glue joint, preferably at a distance of between 5 and 50 mm from the glue joint.

[0030] In the case where the bodywork skin and / or the bodywork box section have orifices, a preliminary step is carried out to isolate the orifices from the external environment.

[0031] Indeed, the bodywork skin and / or the bodywork box section generally have at least one, or even several, through holes. In the case of a bodywork skin covering a lower part of a tailgate box section, the holes correspond in particular to the installation of a police license plate light, a tailgate opening control or a signal light housing for a tailgate, and in the case of a part of a box section, to the installation of a third brake light for a spoiler, etc. The insulation step makes it possible to detect only any leaks due to a localized sealing defect at the level of the glue joint alone, and not the natural evacuation of air through these holes.

[0032] Preferably, the ultrasonic detection device can detect sound waves having a frequency between 5kHz and 50kHz.

[0033] Given the complex shapes that the assembled body shell and skin assemblies can take, and the reverberation effects observed, the noise within the interior volume is more or less disturbed and different noise levels are detected depending on the areas of the glue joint. It is therefore advantageous for the ultrasonic detection device to be able to detect waves over a sufficiently wide range of noise levels.

[0034] The invention also relates to a device for monitoring the integrity of a glue joint to be monitored connecting a bodywork box part and a bodywork skin, defining an interior volume between them, comprising: at least one ultrasonic detection device intended to be arranged in the interior volume; a device for emitting a directional jet of pressurized air opposite a predetermined area of ​​the glue joint; a device for recording a noise level detected by the ultrasonic detection device in the interior volume.

[0035] Preferably, the control device further comprises: a device for comparing the recorded noise level with a reference noise level; and a device for determining an integrity defect in the glue joint if the recorded noise level is different from the reference noise level.

[0036] In the case where the body skin or the part of the box is provided with at least one through orifice, called skin orifice or, respectively, box orifice, at least one vacuum cover intended to cover said at least one skin orifice or, respectively, said at least one box orifice, delimited by two opposite free surfaces, called inner cover surface and outer cover surface, the inner cover surface being provided with two closed contour seals, called respectively inner and outer cover seals, the contour of the inner cover seal being contained in that of the outer cover seal, the cover being crossed by at least one cover suction duct opening, on the one hand, between the two cover seals on the side of the inner cover surface and, on the other hand, on the side of the outer cover surface.

[0037] Such vacuum covers are described in the French patent application filed under number 1911107, by the same applicant. The vacuum covers make it possible to close the orifices in the skin and / or the part of the box during the leak testing process, in order to detect only any leaks due to a leak-proofing defect located at the glue joint alone, and not the natural evacuation of air through these orifices.

[0038] Advantageously, the control device further comprises an air suction device connected to the suction duct of the cover. Brief description of the figures

[0039] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which: [ fig.1 ] There figure 1 is a perspective view of a motor vehicle tailgate being assembled; [ fig.2 ] There figure 2 is an exploded perspective view of the tailgate of the figure 1 ; [ fig.3 ] There figure 2 is a schematic view of a spoiler and an upper cross member connected by an adhesive joint and of a device for controlling the integrity of the adhesive joint according to the invention; [ fig.4 ] There figure 4 is a schematic view of a device for emitting an air jet from the control device of the figure 3 and a section of a spoiler and an upper cross member connected by a glue joint. Detailed description

[0040] It has been represented on the Figures 1 and 2 a motor vehicle body panel 8 known per se from the prior art, which is in this case a motor vehicle tailgate panel.

[0041] The tailgate panel 8 comprises a box 10 which comprises an opening 12 in the box to accommodate a window (not shown in the figures) intended to be attached to the box 10 by gluing.

[0042] More precisely, the box 10 comprises a lower part 14 located below the bezel opening 12, connected to an upper crosspiece 16 by two lateral uprights 18 of the bezel.

[0043] The box 10 is intended to be covered by one or more body skins to form the body panel. As can be seen in the figure 2 , the lower part of the box 14 of the tailgate is here covered with a lower body skin 20 attached to the box 10 by gluing and the upper cross member 16 by another body skin, commonly called a spoiler 22.

[0044] The lower body skin 20 and the spoiler 22 are respectively assembled on the lower part of the box 14 and the upper cross member 16 by continuous beads of glue 24 arranged, again in a known manner, on continuous bonding tracks respectively located on the periphery of the lower part of the box 20 and the upper cross member. The beads of glue 24 here constitute a glue joint between the lower body skin 20 and the lower part of the box 14 on the one hand, and the spoiler 22 on the upper cross member 16 on the other hand. In this way, the body part and the body skin define between them an interior volume V.

[0045] To check the integrity of the seal formed by the bead of glue 24, a device 26 for checking the integrity of a glue seal is used, shown schematically in figure 3. In the following, the glue joint 24 which is checked is the one arranged between the spoiler 22 on the upper cross member 16. This glue joint 24 is shown schematically in figure 3 . It should be noted, however, that all of the following is intended for and applies equally well to the glue joint 24 connecting the lower part of the box 14 and the lower body skin 20.

[0046] The control device 26 comprises an ultrasound detection device 28 arranged in the interior volume V. For example, it is a microphone 28 capable of detecting ultrasound. On the figure 3 , only one microphone 28 is shown, but of course more can be placed in the interior volume V if necessary. The ultrasonic detection device can detect sound waves with a frequency between 5kHz and 50kHz.

[0047] The control device 26 also comprises a device 30 for emitting a directional air jet J under pressure. This is, for example, a nozzle connected to an air compression device or any other device allowing the emission of a directional air jet J under pressure. For reasons of clarity, only the nozzle 30 for emitting an air jet has been shown in the Figures 3 and 4 .

[0048] The nozzle 30 is capable of emitting a directional jet of pressurized air opposite a predetermined area of ​​the glue joint 24. To do this, the nozzle 30 can be held in the hand by an operator, or by an articulated arm of a robot (not shown).

[0049] The control device 26 also comprises a recording device 32 for recording a noise level detected by the ultrasonic detection device (microphone 28) in the interior volume.

[0050] The control device 26 also comprises a device 34 for comparing the recorded noise level with a reference noise level and a device 36 for determining an integrity defect 38 in the glue joint 24 if the recorded noise level is different from the reference noise level. The integrity defect 38 is here in the figures a through hole in the glue joint 24.

[0051] We will now describe the method for checking the integrity of a glue joint 24 to be checked using the checking device 26.

[0052] Firstly, at least one ultrasonic detection device, here one or more microphones 28, is placed in the interior volume of an assembly formed by an upper cross member and a spoiler connected by an adhesive joint not comprising any sealing defect.

[0053] If the bodywork skin and / or the part of the bodywork box concerned has orifices, a preliminary step is carried out to isolate these orifices from the external environment. This step is carried out either before or after the arrangement of the microphones 28.

[0054] In the following, this defect-free glue joint will be called the “reference joint”, and the assembly whose glue joint is a reference glue joint will be called the “reference assembly”. The reference assembly is an assembly of parts identical to those that we wish to test, which may in particular come from the same production line. This is therefore an assembly of a spoiler 22 on an upper cross member 16 whose glue joint does not have any defects.

[0055] It should also be noted that, since the following steps are the same for a reference joint or a 24 glue joint that we wish to test, we refer to the Figures 3 and 4 , and this although the glue joint 24 has a defect 38. In fact, the only difference between the glue joint 24 to be checked and the reference joint is here the absence of defect 38.

[0056] Once the detection device 28 is placed in the reference volume V of the reference assembly, a directional jet of air J is emitted under pressure opposite a predetermined area of ​​the reference glue joint.

[0057] In order to promote noise emissions in the interior volume V and thus improve its detection in the interior volume V, the emission of the air jet J is done at the right of the glue joint 24, as can be seen in figure 4 .

[0058] In order to further improve noise detection, the emission of the air jet J takes place in the immediate vicinity of the glue joint 24, preferably at a distance of between 5 and 50 mm from the glue joint 24.

[0059] Then, the noise level in the reference interior volume V is detected using the microphone(s) 28, and the noise level thus recorded, called the reference noise level, is recorded using the recording device 32.

[0060] The transmission and recording steps described below are performed for a plurality of predetermined areas of the reference glue joint. Shown in the figure 3 three predetermined zones A, B and C which are preferably contiguous, as in the figure 3 .

[0061] These predetermined zones are preferably uniformly distributed along the glue joint 24. In addition, preferably, the meeting of the predetermined zones includes substantially the entire perimeter of the reference glue joint. However, for reasons of clarity only three of these zones A, B, C have been shown on the figure 3 .

[0062] Indeed, given the complex shapes that the body shell and skin assemblies (here a spoiler and an upper cross member) can take once assembled and the reverberation effects thus created within the interior volume of the assembly, the noise levels detected there, even in the absence of a defect, differ significantly depending on the areas of the reference glue joint.

[0063] A reference noise value is therefore recorded for each of the predetermined zones. This gives a sound map of the reference glue joint, i.e. a set of pairs of associated values, namely a reference noise level associated with a predetermined zone.

[0064] It will be noted that in a variant, the value of the reference noise level associated with a predetermined area of ​​the reference glue joint may be the result of an average of noise levels recorded for the same predetermined area of ​​several identical compliant parts.

[0065] In still other variants, the reference noise levels per predetermined zone, in other words the sound mapping as defined above, may include more data, called reference data, linked to the noise level value per predetermined zone recorded for one or more reference adhesive joints. It will thus be possible to record a minimum and / or a maximum noise level recorded by taking a reading of the noise level over a given period of time, to take averages of noise levels, to calculate a standard deviation of the noise levels recorded, etc. These reference data will be compared two by two with data of the same nature linked to the noise level recorded for the adhesive joint to be checked.

[0066] Once this mapping has been obtained, at least one ultrasonic detection device, here one or more microphones 28, is placed in the interior volume V of an assembly to be controlled.

[0067] Then, a directional jet of air J under pressure is emitted opposite a predetermined area of ​​the glue joint 24. It will preferably be ensured that the conditions of emission of the air jet J are the same as those of the emission of the air jet J opposite the reference glue joint, in order to obtain a more reliable comparison of the recorded noise levels.

[0068] Furthermore, still preferably, the predetermined area of ​​the reference glue joint corresponds to the same predetermined area of ​​the glue joint 24 to be checked. The directional air jet J will therefore be emitted opposite the same predetermined areas, here represented by areas A, B, C on the figure 3 . For this purpose, the nozzle 30 can be run along the glue joint 24 to be checked by an operator.

[0069] However, preferably, the nozzle 30 will be held by an articulated arm of a robot (not shown) which performs a sweep of the glue joint 24 so as to emit the directional air jet J looking at predetermined areas. Preferably, the robot performs such a sweep so that the nozzle 30 is placed at a fixed distance from the glue joint 24 during the sweep, in other words so that the directional air jet J is always emitted at the same distance from the glue joint 24 during the sweep. In a preferred embodiment, the sweep performed by the robot will be over the entire perimeter of the glue joint 24.

[0070] The noise level detected by the ultrasonic detection device 28 in the interior volume V is then recorded and the presence of an integrity defect in the glue joint is determined according to the recorded noise level.

[0071] For this, preferably, the noise level thus recorded is compared with the reference noise level recorded for the same predetermined area. Thus, if for example the noise level recorded for area A of the reference glue joint has been recorded, the noise level recorded for the same area A of the control glue joint 24 is compared.

[0072] If the noise level thus recorded is different from the reference noise level, it can be determined that there is an integrity defect 38 in the glue joint 24.

[0073] Taking the example of the figure 3, since zones A and C do not have any defect in the glue joint 24, noise levels in these zones will be found that are identical or very close to the noise levels found for these respective zones A and C of the reference joint. On the other hand, since zone B includes a sealing defect 38, a different noise level, in practice higher, than the noise level for zone B of the reference glue joint will be found for zone B.

[0074] By carrying out these successive steps for predetermined areas whose meeting includes substantially the entire perimeter of the glue joint 24, it is possible to determine where any integrity defects are located over its entire perimeter and to determine whether the glue joint 24 is compliant.

[0075] The invention is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art.

[0076] In particular, it is possible to use the method and device for checking the integrity of a glue joint to check the tightness of other body panels resulting from the assembly of two panels by gluing. List of references

[0077] 8: Body panel (tailgate) 10: Motor vehicle body 12: Tailgate window opening 14: Lower part of the body 16: Upper cross member of the body 18: Side pillars of the body 20: Body skin 22: Spoiler 24: Glue joint 26: Device for checking the integrity of the glue joint 28: Ultrasonic detection device (microphone) 30: Device for emitting a directional jet of pressurized air (nozzle) 32: Device for recording a noise level 34: Device for comparing the noise level 36: Device for determining an integrity defect 38: Integrity defect J: Air jet V: interior volume

Claims

1. Method for checking the integrity of a glue joint (24) which is to be checked and which connects one portion of a body box (16) and a body skin (22), which define an inner volume (V) to be checked therebetween, characterized in that it comprises the following steps, carried out in this order: - arranging at least one ultrasound sensing device (28) in the inner volume (V); - emitting a pressurized directional air jet (J) opposite a predetermined area (A, B, C) of the glue joint (24); - recording a noise level detected by the ultrasound sensing device (28) in the inner volume (V); and - determining an integrity defect (38) in the glue joint (24) according to the recorded noise level.

2. Checking method according to claim 1, further comprising a step of comparing the recorded noise level with a reference noise level; and wherein an integrity defect (38) in the glue joint (24) is determined if the recorded noise level is different from the reference noise level.

3. Checking method according to claim 1 or 2, further comprising the following steps, carried out before the step of arranging at least one ultrasound sensing device (28) in the inner volume (V) to be checked: - arranging at least one ultrasound sensing device (28) in the inner volume, called reference volume, defined by a body box portion (16) and a body skin (22) connected by a glue joint (24) not comprising any tightness defect, called reference glue joint; - emitting a pressurized directional air jet (J) opposite a predetermined area (A, B, C) of the reference glue joint; - detecting the noise level in the reference inner volume; and - recording the noise level thus detected, called reference noise level.

4. Checking method according to claim 3, wherein the predetermined area of the reference glue joint corresponds to the same predetermined area of the glue joint to be checked.

5. Checking method according to one of the preceding claims, wherein the emission and recording steps are carried out for a plurality of predetermined areas (A, B, C) of the glue joint.

6. Checking method according to claim 5, wherein the predetermined areas (A, B, C) are uniformly distributed along the glue joint (24).

7. Checking method according to claim 5 or 6, wherein the predetermined areas (A, B, C) are contiguous and the union of the predetermined areas (A, B, C) includes substantially the entire perimeter of the glue joint (24).

8. Checking method according to one of the preceding claims, wherein the emission of the air jet (J) takes place perpendicular to with the glue joint (24).

9. Checking method according to one of the preceding claims, wherein the air jet (J) is emitted in the immediate vicinity of the glue joint (24), preferably at a distance of between 5 and 50 mm from the glue joint (24).

10. Checking method according to one of the preceding claims, wherein, if the body skin (22) and / or the body box portion (16) in question contain orifices, a preliminary step is carried out for isolation of the orifices with respect to the external environment.

11. Checking method according to one of the preceding claims, wherein the ultrasound sensing device (28) is able to detect sound waves whose frequency is between 5 kHz and 50 kHz.

12. Device for checking the integrity (26) of a glue joint (24) which is to be checked and which connects one portion of a body box (16) and a body skin (22), which define an inner volume (26) therebetween, comprising: - at least one ultrasound sensing device (28) intended to be arranged in the inner volume (V); - a device for emitting a pressurized directional airjet (J) opposite a predetermined area (A, B, C) of the glue joint (24); - a device (32) for recording a noise level detected by the ultrasound sensing device (28) in the inner volume.

13. Checking device (26) according to claim 12, further comprising: - a device (34) for comparing the recorded noise level with a reference noise level; and - a device for determining an integrity defect in the glue joint (24) if the recorded noise level is different from the reference noise level.

14. Checking device (26) according to claim 12 or 13, further comprising, the body skin (22) or the box portion (16) being provided with at least one through orifice, called the skin orifice or, respectively, box orifice, at least one vacuum cover intended to cover said at least one skin or, respectively, said at least one box orifice, delimited by two opposite free surfaces, called the inner cover surface and the outer cover surface, the inner cover surface being provided with two seals with a closed contour, respectively called inner and outer cover seals, the contour of the inner cover seal being contained within that of the outer cover seal, the cover being passed through by at least one suction port of the cover opening, on the one hand, between the two cover seals of the side of the inner cover surface and, on the other hand, on the side of the outer cover surface.

15. Checking device (26) according to claim 14, further comprising an air suction device connected to the suction port of the cover.