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The present invention concerns a device able to keep in a partially closed position the door of a motor vehicle when this undergoes the various manufacturing processes.
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In the motor vehicle manufacturing, the coating of the metallic parts with antioxidant and the following painting are executed when the doors are already mounted by hinges to the metal structural covering that is fixed to the chassis (said metal covering will be called "frame" for brevity in the following). In this way it is guaranteed that:
- the painting is uniform on the whole motor vehicle;
- there are no risks scratching the already painted surface when mounting of the doors to the vehicle.
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During said manufacturing processes it is necessary that:
- the doors don't stay attached to the frame of the vehicle (e.g. completely closed) but at a distance of a few centimeters;
- the doors stay closed but at the above mentioned distance from the frame during the various steps along all the process;
- the doors can be open and closed again by the operators during the process.
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Since the doors are free to rotate around hinges, without any kind of brake or stop, it is necessary to attach to the frame a device that allows the above conditions.
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Among the solutions proposed in the known technology (prior art) the documents
EP931895A1 ,
US6656278B2 and
EP1781878A0 give a clear picture of the whole issue.
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For convenience, in the attached
figure 9, 10 and
11 are reported
Fig. 5 of
EP931895 ,
Fig. 2 of
US 665627 and
Fig. 2(B) of
EP1781878 respectively, and reference numbers and letters are added on purpose that will be called In the following of this document.
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From the cited documents the features of devices that define the known technology are the following:
- the devices are mounted attached on the frame (33 Fig. 9 or 35 Fig. 10 or 46 Fig.11 ) in an area where it's possible to exploit any hole or hollow in the door (32 Fig. 9 , 36 Fig. 10 or 45 Fig.11 ) to guarantee the hooking.
- The devices are able to automatically get into operation if the operator closes/opens the door, that is to say they do not need other direct intervention on them by the operator. Moreover, to open/close the door no other actions are needed than usual opening/closing. In Fig. 9, Fig. 10 and Fig. 11 the direction and versus for closure "C" and opening "O" of the door 32 Fig. 9 , 36 Fig. 10 and 42 Fig. 11 is indicated.
- The activation/releasing of the devices requires a force greater than the one needed to close/open the door of the vehicle.
- The device, in its version EP931895 ( Fig. 9 ), is based on a thin plate 31, made of plastic material or composite (plastic plus fiber glass) or spring steel. When the door 32 is being closed, before touching the frame 33 of the vehicle, the thin plate 31 gets in touch with the sheet of the door 32 that make said thin plate bend. After a certain traverse "S" (normally a few centimeters), the sheet of the door 32 can pass the thin plate 31 that springs back in its rest position (we can say that it snapped). Its travel stops when the door 32 Impacts on a buffer 34. The buffer is part of the thin plate based devices that are reported in the prior art. So the door 32 is trapped between the buffer 34 and the thin plate 31. When opening the door 32 the thin plate 31 snaps back in the opposite way.
- The device, in its version US6656278 ( Fig. 10 ), needs that the door 36 includes a hole or and plane hollow 38, the elastic swell 37 can house in. In the position of Fig. 10 the door 36 is hooked to the frame 35.
- The device, in its version EP1781878 ( Fig. 11 ), is still based on an elastic element 48 but the interaction with the sheet of the door 47 is done by means of an rotating element 40 constrained to rotate around one axis of the body 39 that can bend in the zone 41. When the door 42 is being closed, the wheel 40 interacts with the sheet of the door 47, before touching the frame 46. An additional force allows the rotation of the wheel and the bend of the body 48 in the zone 41. The sheet of the door 47 can pass the wheel because the body 48 can bend. As soon as the wheel has been passed, the sheet 47 will be constrained between the wheel 40 (at the distance (j)) and the body 48 against the edge 43. When opening the door the sheet will pass again the wheel that will rotate in the opposite way back.
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Several problems have been found even on the advanced solution mentioned above when used in some manufacturing plants where much more strict quality models are followed. In particular the solution based on bend of a thin plate has the following problems:
- a) If a plate of plastic or composite is used it is scratched during friction of the sheet of the door on it and the related chips fall on the just painted surfaces of the frame and of the door where the paint is still wet, therefore the coated surface results compromised.
- b) If a plate in metallic material (spring steel) is used, its friction against the metal can damage the sheet of the door. In particular the thin antioxidant coating created after the cataphoresis process can be removed, so creating small zones exposed to the oxidation.
- c) Regardless of the material used to make the plate, friction of it on the edge of the sheet of the door can result in chips of paint that coated the plate itself. Therefore this can compromise the still wet surfaces of the vehicle, because said chips can fall on them.
- d) Regardless of the material used to make the plate, due to the intrinsic geometry of the "thin plate system", said plate needs a certain allowance "S" (see Fig. 9 ) to snap back. In other words, a certain allowance is needed so that the door 32 must travel in the closure phase to allow the plate 31 to return in its rest position. The allowance "S" must be equal or less than the distance "D" that the door can travel before impacting the buffer 34. So the thin plate 31, after snapping back, will return in its rest position. Due to pure geometric reasons, when the thin plate 31 is in its rest position, between it and the door 32 we see a clearance of typically one centimeter. Even in the best case where "S"="D", the door 32 is free to open until the thin plate 31 is touched. This allowance is not tolerable in some painting plants for two reasons:
- i) The vehicles, during the movements, must move with closed doors and go through high accelerations. As a consequence huge inertial forces arise against the door that could open or close them according to the way of the movement. Specific measurements demonstrated that the bigger is the allowance "S" between door 32 and thin plate 31 the easier that the thin plate cannot hold the door that might open during the vehicle movement in the manufacturing phases. Indeed, as long as the inertial force is fixed, the bigger is the allowance the bigger is the kinetic energy of the door when this impacts the thin plate. The drawback of accordingly dimensioning the elastic resistant force of the thin plate to resist to the inertial forces is that the operator cannot open the door with a force suitable for normal operations.
- ii) In some phases, during the process, the doors are open and closed by a machine (robot). During the closure phase the robot brings the door to the initial position (closed door). Due to the said allowance it is not sure that the thin plate has snapped back. The robot has not generally the ability to know if after the closure the thin plate has snapped back or not. Therefore it's liable to go ahead with the movement of the vehicle without activating the devices.
- e) During the cataphoresis/painting process the vehicle passes through ovens. The internal temperature in these ovens is around 180°C. As the devices are based on the bend of a thin plate, the mechanical properties will be modified if it is made of plastic or composite material. If the vehicle goes through accelerations after exiting the ovens, it is possible that the devices, still warm, cannot hold the door in the closed position.
- f) The devices are based on the bend of a thin plate. During the painting of the vehicle the paint will cover also the plate. If the door is open before the paint is catalyzed, it can splash due to bend and next release of the thin plate. So drops of till wet paint can stick to the already painted surface of the vehicle.
- g) Some fitting tolerances exist for the door to be mounted to the frame. It can happen that the distance between the sheet of the door 32 and the sheet of the chassis 33 when the door is completely closed is not always the same from door to door. As a consequence, the contact line of the edge of the sheet 32 on the thin plate 31 can be more towards the base of the thin sheet than towards the tip. Therefore, due to pure geometrical reasons, it can happen that the sheet 32 has impacted the buffer 34 but the thin sheet 31 has not snapped back even though the door 32 has advanced the distance "S". In this situation the door cannot stay closed because the device cannot keep it hooked.
The solution US6656278B2 ( Fig. 10 ) has the following problems: - h) The device in not usable when the sheet of the door doesn't contain a hole or a plane hollow 38;
- i) The elastic swell 37, made of plastic material, might not be as strong as necessary to resist to the sharp speed changes during the movement of the vehicle.
- j) The device is based on the friction of a plastic elastic swell on the edges of the hole 38. Therefore the plastic the device is made of can scratch when the paint of the vehicle is still wet. In this case chips of plastic material can stick to the painted surfaces, compromising their integrity. If the elastic element were strengthened using a more elastic and tough plastic this problem would worsen because the said friction would increase.
The solution EP1781878A0 ( Fig. 11 ) has the following problems: - k) If the body 48 is made of plastic material, the bend parameters are highly impacted by the temperatures, making the device useful Just at room temperature.
- l) Regardless of the used material to make the body 48, when the wheel 40 goes through bend, its axis could not stay parallel to its rest position. Indeed it is not guaranteed that the force of bending stays in the plane parallel to the one containing the wheel.
The invention alms at eliminating the said drawbacks of the prior art. It includes a device that:
- Guarantees that the inertia due to the acceleration during the movements of the frames do not open the doors;
- Allows the operators to open manually the doors by a suitable force, during the manual phases in the manufacturing processes;
- Allows to the robot to open the doors and close them back during the manufacturing processes;
- Allows not to damage the surfaces just coated with antioxidant and paint;
- Allows all the above said features inside the dimensional errors of the doors, frame and of relative position between them;
- Can be mounted before the processes that involve high thermal Jump had started and removed after they have finished.
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The purposes of the list above are achieved by the device to keep the doors of a motor vehicle in a partially open position during the manufacturing process, according to this invention, that includes the features of the attached independent claim 1.
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Advantageous features of this invention are disclosed in the attached dependent claims.
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Basically the device according to this invention, that allows to keep the doors of a motor vehicle at a specified distance from the frame during the surface coating process, includes a central body that stands on a base, which is attached to the frame of the vehicle by means of a bolt through a hole existing in it. The central body includes a groove that houses a wheel that is constrained to translate along a slide and rotate around its axis. Said wheel is pushed out along the symmetry axis of the central body by a spring that is hosted inside the central body. From the central body outwards is a support on which an element is rigidly fitted to stop the complete closure of the door.
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Further features of the Invention will be clarified by the following detailed description concerning forms purely illustrative of the invention, so not restrictive, showed in the attached draws, in which:
- Fig. 1 is a axonometric view of a device according to this invention;
- Fig. 2 is a median section view through the plane II-II in Fig. 1 ;
- Fig. 2(a) is an enlarged view of the detail inside the circle (P) in Fig. 2 ;
- Fig. 3 is an exploded view of the device of Fig. 1 , where the axonometric position is opposite to the one in Fig. 1 ;
- Fig. 4 shows schematically the zone of a vehicle where the device is mounted; Fig. 5 shows, in enlarged scale, the interaction of the device when mounted with the door in the closure phase;
- Fig. 6 is a view like Fig. 5 , but with the door closed;
- Fig. 7 shows another version of the device ready to be attached to the frame of the vehicle;
- Fig. 8 shows the devices of Fig. 7 ready to be activated;
- Fig. 9 shows a device of the prior art and corresponding to the Fig. 5 of the document EP931895A1 ;
- Fig.10 shows a device of the prior art and corresponding to the Fig. 2 of the document US6656278B2 .
- Fig. 11 shows a device of the prior art and corresponding to the Fig. 2(b) of the document EP1781878A0 .
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The device according to the invention allows keeping the doors of a motor vehicle at a specified distance from the frame during the surface coating process. It includes a central body that stands on a base 1. Said base includes a hole 2 to fasten the device to the frame of the vehicle by means of a bolt (not showed). A rod 3 extending downwards from the base 1 is used as a guide to make it ease to position the device in the housings of the frame. The swells 16 and 16' Fig. 2 reproduce the same form of the said housings in order to fit them and guarantee that the device is placed in the correct position.
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The central body 5 is a tapered cylinder with a central groove 4 that allows the housing of a wheel 6; indeed the thickness of the wheel 6 is a few tenth of one millimeter less than the groove 4 width. Said wheel includes an axial pinion 11, 11' Fig. 2(a) that can translate in the corresponding slides 12 and 12' allowing the wheel 6 to move along the symmetry axis of the central body 5, until eventually to enter completely in said central body. Since the device is made conveniently in thermoplastic resin, the two opposite walls 17 and 17' that border the groove 4, can bend allowing the wheel 6 to be housed (during the assembly phase of the device) in the groove 4, although the total thickness of the wheel 6 and the pinion 11, 11' is higher than the width of the groove 4. On the top of the central body 5 there are two sloping planes 7 e 7' Fig.2(a) that are used to obtain the above said bend. Indeed, during the assembly of the device the wheel 6 is inserted inside the groove 4 by pushing the pinion 11, 11' on the sloping planes 7 and 7' downwards. Once the two walls 17 and 17' are widen apart, the pinion houses in the guides 12 and 12' and cannot exit any more due to the undercuts 18 and 18' produced under the sloping planes 7 and 7'.
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The wheel 6 Fig. 2 is thrust outside against the stops 18 and 18' by a helical spring 13. Between the spring 13 and the wheel 6 there is a sliding block 15 that on one side is housed in the inner part of the spring 13 and on the other side is sliding under the wheel 6. The other ending of the spring 13 is kept integral to the bottom plane of the base 1 by a cap 14. Shoe 15, spring 13 and cap 14 house in the inner of the central body 5 that has some concentric cavities suitable to contain them as showed in Fig. 2 .
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The undercuts 18 and 18' are slanting against the axis of the central body, at about 15°. The same sloping is reproduced on the pinion 11, 11'. Due to this, the spring force, vertical In direction, has an orthogonal component that keep close the walls 17 and 17'. This feature is used to guarantee that the wheel stay in its housing even though the plastic material the device is made of goes through a softening caused at high temperature.
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Orthogonally to the rotation axis of the wheel, from the central body 5 Fig. 1 , a support 8 starts that finishes on the other side with two slides 19 Fig. 3 . On said support a buffer 9 is housed through said slides 19 that are tapered enough not to permit it to come out. A stop 20 ensures that the buffer 9 is positioned always at the same distance. The buffer 9, made of plastic material, contains solidly a bumper 10 Fig. 1 , made of rubber, suitable to absorb the impacts.
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All the materials used by all the components of the device maintain their physical properties after cycles of one hour at temperature of 200°C.
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In the variant of Fig. 7 the support 21 Includes a ring 23 that can pivot around the central body 5 until an elastic stop 22 snap into the groove 4 where the wheel 6 Fig. 8 houses. The advantage of this version is that the support 21 can be made of a material softer than the whole device and it doesn't require adding a further element as in case of the buffer 9 and bumper 10 Fig. 1 .
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The device is assembled starting by the components showed in Fig. 3 . Both the manual and the automatic assembly are suitable for this device.
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Briefly, the device according to Fig. 1, Fig. 2 and Fig. 3 is assembled in this order:
- Insertion of the shoes 15 on the spring 13;
- Insertion of the spring 13 Inside the central body 5;
- Insertion of the cap 14 and welding of it on the bottom surface of the base 1;
- Insertion of the wheel 6 through the planes 17 and 17' in the groove 4.
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The buffer 9 is inserted in the slides 19 directly by the operator of the motor vehicle manufacturing process.
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For the variant of Fig. 7 and Fig. 8 the order of the assembly is the following:
- Insertion of the shoes 15 Fig. 3 on the spring 13;
- Insertion of the spring 13 inside the central body 5;
- Insertion of the cap 14 and welding of it on the bottom surface of the base 1;
- Insertion of the support 21 fitting the ring 23 around the central body 5 until reaching its base;
- Insertion of the wheel 6 through the planes 17 and 17' In the groove 4.
The support 21 is rotated as in Fig. 8 directly by the operator of the motor vehicle manufacturing process.
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According to Fig. 4 , the device is mounted to the frame 25 of the motor vehicle In the zone 28 dedicated to the bridge where the final lock of the door is anchored. The device interacts with the internal sheet of the door 26 in the zone 27.
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The operator opens the door and inserts the rod 3 in one of the square hollow dedicated to the anchoring bridge. Inserts the swells 16 and 16' Fig. 2 in the corresponding hollows, screws a bolt (not showed) in the threaded hole in the frame through the hole 2 In the base 1. The device is attached in zone 28 as showed in Fig. 4 , with the support 8 outwards the vehicle and without the buffer 9. In the variant of Fig. 7 is not important the orientation in the mounting phase. In the manufacturing phases when the relative position between doors and frame is tuned, the buffer 9 In not present, to allow the correct adjustment of the doors against the frame of the vehicle. Afterwards , when the vehicle is ready to go through the cataphoresis and painting processes, the operator himself will insert the buffer 9 on the support 8 through the slides 19 Fig. 3 or, In the variant of Fig. 7 , rotates the support 21 by 90° outside the vehicle.
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When the buffer 9 Fig. 3 is mounted or, in the variant of Fig.7 , the support 21 is rotated, the door can be closed. The zone 29 Fig. 5 of the cavity 31 of the internal sheet of the door is used to house the lock of the door. Said zone of the sheet interacts with the device of this invention when the door is approaching the frame of the vehicle. The sheet of the door Impacts the wheel 6 Fig. 1 In the zone 29 Fig. 5 when the door is a few centimeters far from the complete closure.
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If the door is pushed further, the wheel 6 rotates around its axis and translates downwards along the slides 12 and 12' Fig. 2 compressing the spring 13. The zone 29 Fig. 5 is a segment constant of this motion, that is, since the rotation is caused by the edge of the internal sheet of the door, the contact line of wheel against edge never changes during the motion.
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When the contact zone of the wheel against the edge of the sheet passes the crown of the wheel, the spring 13 Fig. 2 goes through a decompression, autonomously helping the door to close.
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The door keeps closing until the bumper 10 Fig. 6 impacts the sheet of the door in the zone 30 Fig. 6 . In this static position, the device acts as locking element of the door as, to open it, at least a force is needed to compress again the spring.
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The dimensions of the device are adapted to the cavity 39 in the internal sheet of the door. So if the buffer 10 is into contact with the sheet in the zone 30 Fig. 6 , the wheel is always into contact with the sheet in zone 29 and the door cannot move freely. At this stage the wheel exerts a locking on the door.
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This invention offers some advantages that are basically the overcoming of the problems of the prior art already commented. Below is reported the explanation why the problem is overcome by this invention following the same order used when commenting the issues with the prior art.
- a) This invention doesn't have this problem because the contact zone 29 on the wheel 6 is constant during the rotation motion of said wheel, so there is no sliding friction between plastic (the wheel) and metal (the door sheet).
- b) This invention doesn't have this problem because the device doesn't include external parts of metal.
- c) This invention doesn't have this problem for the same reason at bullet a).
- d) This invention doesn't have this problem. Indeed according to Fig. 6 , one end (zone 30) of the profile of the cavity in the internal sheet of the door is blocked by the bumper 10 and the other end (zone 29) is blocked by the wheel 6 by means of the thrust of the spring 13.
- e) This invention doesn't have this problem because high temperatures cannot modify the properties of the wheel 6 and of the bumper 10, which have thicknesses about respectively 4 and 10 mm.
- f) This invention doesn't have this problem because when the device works there is no bend of elastic plastic parts.
- g) This invention doesn't have this problem because, even in case of strong differences in the positioning of doors to the frame, the zone 29 will happen to be closer/farer to the top of the central body 5 but the device is activated as well.
- h) This invention doesn't have this problem because it is applicable if the door includes a not plane cavity (see Fig. 5 ).
- i) This invention doesn't have this problem because the locking force is guaranteed by the steel spring 13.
- j) This invention doesn't have this problem because its working is based on the rolling of the wheel 6 on the internal sheet of the door In the zone 29.
- k) This invention doesn't have this problem because the elastic element 13 is not part of the structure of the central body 5 so that it can be made of a different material than the central body itself, furthermore suitably chosen for the high temperatures.
- l) This invention doesn't have this problem because the lateral faces of the wheel 6 are constrained between the planes delimiting the groove 4.
Moreover further advantages have been identified: - m) It can happen that the door can be mounted forward or backward, in the driving direction, but still within the mounting tolerances. From Fig. 6 is obvious that the device is able to balance the differences until the extent that the contact zone 29 is either on the top of the wheel 6 or the edge of the sheet is coming very close to the top of the central body 5.
- n) Compared with the solution where the locking force is based on a bend spring of plastic, according to this invention the plastic body of the device can be made of cheaper plastics, that might not have special elastic properties or that might not hold them unaffected after several jumps at high temperatures.
- o) The locking force of the device can be easily changed by changing conveniently the parameters of the spring 13.
The advantages of this invention previously described are the consequence of the innovative features of the invention compared with the prior art. These are basically the following:
- The portion of the device interacting with the sheet of the door of the vehicle has no relative shift with the sheet. In other words, as the rotation is triggered by the edge of the sheet, the contact line of the wheel against the edge never changes during the motion so there is no sliding friction between the wheel and the sheet of the door. This feature guarantees that there are no degradations of the contact surfaces and the quality of the coated surfaces is not compromised.
- As the contact line between wheel and the edge is not changing during the motion, when the door is closed until the stop, it is still returned towards this position. This guarantees that there is no allowance that instead can permit the door to open in presence of inertial forces.
- The element that has the locking force (helical spring, in the version showed of the device) can be made of materials that keep constant the elastic properties during the coating processes where the environment temperature changes within a wide range (≒ 10-200°C).
- The element that has the locking force (helical spring, in the version showed of the device) can be easily adapted to the various locking need because it is a separated part, so it can be easily replaced.
- The wheel is constrained to move on a plane even though the force that generates the rotation and translation motion is inclined on the said plane.
- The device is including a stop to limit the closure of the door to a certain extent. It is possible to mount the device to the vehicle without the stop being in the way disturbing the activities of tuning of the door clearance. Indeed the operator can activate the stop when it is actually needed.
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Of course this invention is not restricted to the specific form previously described and showed in the attached figures but many modifications can be conveniently introduced without straying from the subject of the invention itself defined by the attached claims. So, for example, the wheel 6 can be inserted in the groove 4 from the top of the central body 5, according to the attached figures, or from other sides and the spring 13 can be replaced by another compression element having the same function.
