FR2741990A1 - CONTROL DEVICE, IN PARTICULAR FOR THE TRIGGERING OF RETENTION MEANS IN A VEHICLE - Google Patents

Abstract

This control device, in particular for triggering retaining means in a vehicle, comprising a housing, which comprises a connector (4), and an electrical circuit which is arranged in the housing and comprises a pressure sensor (21). According to the invention, it is characterized in that the components (2, 21) of the electrical circuit are connected in an electrically conductive manner by means of a structure (1) cut from a metal strip, in that the cut-out structure (1) contains male pins (42) of the connector (4) and in that an area in the housing wall (323) is made as a membrane (322) for pressure transmission.

Description

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  The invention relates to a control device, in particular for the triggering of retaining means in a vehicle, comprising a housing, which comprises a connector, and an electrical circuit which is arranged in the housing and comprises a pressure sensor. A control device which contains an electrical circuit, arranged in a housing and comprising a pressure sensor, and which is connected for example to a cable bundle by means of a connector integrated in the housing finds application in all technical fields that one can imagine and in which a pressure measurement is necessary. One of these technical fields is the automobile construction technique which imposes on such a control device conditions to be met at a particularly high level with regard to its size / dimensions, its insensitivity to influences middle

  environment, its reliability and its manufacturing costs.

  Recently, such control devices have also been used to control retaining means, such as an inflatable protective bag (known as an "airbag"), in a motor vehicle. Thus, for example, such a control device is arranged in a lateral part of the motor vehicle, such as the driver's door. In this case, the pressure sensor is subjected to an increase in the air pressure which occurs in a cavity of the side door and which is due to a deformation of this side door under the effect of a transverse collision and depending on the severity of the collision, it triggers a side airbag or other means

  restraint presented by the vehicle.

  In an international application benefiting from an earlier date (PCT / DE 95/00907), it is proposed to have a silicon pressure sensor on a conventional printed circuit board. The printed circuit board including the pressure sensor is disposed in a housing having an opening. Between the opening of the case and the printed circuit board,

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  a plastic sleeve surrounds the pressure sensor. At the height of the opening of the housing, the sleeve is closed by a membrane, so that the sleeve, the membrane, the printed circuit board and the pressure sensor define a space of small volume which is filled with air and which transmits to the pressure sensor, in an almost undistorted manner, a pressure signal applied to the membrane. Male connector pins which are bent at right angles through the housing and are soldered to the board.

printed circuit board.

  Due to the relatively large dimensions of this known control device which are due in particular to the previously described embodiment of the connector, the volume of the interior space of the control device is too large to be able to be used to transmit the pressure between the opening of the housing, the sealing of which is ensured by the membrane, and the pressure sensor, without then taking into account a weakening / distorted signal value which is significant. It is for this reason that the sleeve and the membrane, made in one piece with the latter, would be tightened between the printed circuit board and the opening of the housing, above the pressure sensor, and that, this fact, the volume used for the transmission of pressure would be made as small as possible. Although this solution ensures good signal transmission, it is however expensive and complex with regard to mounting due to the

  constituent elements which are necessary in addition.

  The object of the present invention is to provide a control device which avoids the drawbacks of the known control device and therefore in particular uses the entire volume of the interior space of a control device.

  command to transmit pressure signals.

  This object is achieved by means of a control device, of the generic type considered, which is characterized in that components of the electrical circuit are connected in an electrically conductive manner by

  through a cut structure (take away

  piece) in a metal strip, in that the cut structure contains male connector pins and in that an area located in the housing wall is produced in the form of a membrane used for pressure transmission. Thus, components of the electrical circuit, such as the pressure sensor itself, are connected in an electrically conductive manner by means of a structure cut from a metal strip. The cut structure contains male pins of a connector. Thanks to the use of such a cut structure, also called "cut grid" or "conductive armature (leadframe)", instead of a conventional printed circuit board, the volume of the interior space of the control device which is filled with air is clearly reduced, given that, in particular in the region of the connector and because of the male pins produced in one piece with the cut structure, the horizontal extent of the control device is reduced. Thus, an area located in the wall of the housing can be made in the form of a membrane and the reduced volume of the interior space of the control device can be used for the transmission of pressure, without a delimited space having to be provided in the control device for the transmission of pressure by means of additional elements. Excellent transmission of pressure signals is obtained, since the membrane arranged on the housing protects against influences from the surrounding environment and thus the membrane of the pressure sensor itself can remain unprotected. It is therefore not necessary either to provide the membrane of the pressure sensor with a protective layer which would reinforce the inertia of this membrane, so that the pressure sensor is no longer subjected to pressure, but also to accelerations. If the pressure sensor is for example mounted on a vehicle, it is subjected to accelerations which

  thus intervene in its output signal.

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  A part of the connector used to house an associated socket is directly mounted / produced by injection molding on the cut structure, and this as close as possible to the electrical circuit. In addition, filter capacitors for electromagnetic shielding are arranged directly at the point where the male pins enter the housing, so that conventional filter plugs, which take up space, are superfluous. Thus, not only the volume of the interior space is reduced, with the aforementioned consequences, but also the filter capacitors thus arranged provide the best possible protection against the penetration of electromagnetic radiation, since the interior of the control device no longer includes conductive tracks / unshielded male pins which

would serve as an antenna.

  In addition, the cut-out structure may include, either inside the housing, or - insofar as the cut-out structure passes through the housing - outside of this housing, one or more bores by means of which the control device can for example be fixed on a support arranged in the motor vehicle. Such a fixing then serves at the same time as a grounding bypass. Thus, in comparison with known control devices, there is the saving of an additional element which has hitherto provided the connection between the ground provided on a conventional printed circuit board and an external ground terminal. The arrangement thus adopted also makes it possible to reduce the extent of the control device and

  therefore the volume of its interior space.

  Preferably, the cut structure also includes flat areas, used for electromagnetic shielding, which are made in one piece with areas of the cut structure which serve as conductive tracks for the electrically conductive connection between the components. This development of the invention also reduces the extent of the control device and therefore the volume of its interior space, since sheets

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  separate shielding and additional layers of ground in printed circuit boards are superfluous. Preferably, integrated circuits are arranged without housing on the cut structure. The advantages presented by the aforementioned developments are

  also valid for this development of the invention.

  The use of a cut structure also requires that conductive tracks of this cut structure extend without crossing. This fact results in a relatively small number of components being able to be placed on such a cut structure and that highly integrated circuits, such as multi-chip modules, are used more and more.

  which further reduces the spatial extent of the electrical circuit.

  According to other developments of the invention, it can be provided: - that the housing is made of plastic, - that a housing part of the connector, serving to receive an associated socket, and a part of the housing are made of a part, - that the zone produced in the form of a membrane is formed in one piece with the housing and has a thickness which is thinner than the wall of the housing, - that the housing has an opening on which a flexible plastic membrane is arranged which is connected to the housing in a watertight manner, - that the pressure sensor is integrated and arranged on the cut structure in the form of an integrated circuit without housing, - that part of the cut structure passes out of the housing and that the control device is fixed by this part on a support, - that the cut structure includes zones

  planes used for electromagnetic shielding.

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  Examples of the invention and its developments are set out with reference to the drawings. We see: in Figure 1, a cutout structure for a control device according to the invention, in Figure 2, a control device according to the invention in top view, in Figure 3, a view of side of the control device according to the invention of Figure 2 by the line

A-A,

  in FIG. 4, a side view of the control device according to the invention in FIG. 2 from the line B-B and,

  in Figure 5, a known control device.

  FIG. 1 represents a structure 1, cut (with a punch) from a metal strip 12, as used in a control device according to the invention. A second structure cut from the metal strip 12 is connected to it on the right of the dashed line. The cut structure 1 comprises conductive tracks 11 which interconnect, in an electrically conductive manner, electrical components 2 and a pressure sensor 21 and which at the same time serve for fixing the components 2, 21. Connection lugs components 2, 21 pass through holes in the cut structure 1, then are welded on the rear face of this cut structure 1, or else are folded back on themselves so that they can be welded on the front face of the cut structure 1. The latter further comprises male pins 42 of a connector. Flat areas 13 are used for electromagnetic shielding and are used in the present embodiment as part of the cut-out structure 1. By means of fixing holes 14, the metal strip 12 is transported on the assembly line for manufacturing. . Flat areas of the metal strip can also be arranged inside the cut structure between conductive tracks or else be folded back to form marginal areas of the cut structure, so as to provide the best possible protection against screw for the penetration of electromagnetic radiation. The fixing holes can be used not only to advance the metal strip on the assembly line, but also to fix, on a support, the control device considered which comprises the cut structure. To improve contact, at least some parts of the

  male pins may have a gold coating.

  Such a cut structure is produced by cutting a grid structure (with a cookie cutter) from the metal strip. Then, zones of this grid are provided with plastic bridges by injection and interruptions of conductive tracks are made by cutting into the grid structure, so that if necessary, the different conductive tracks can be isolated each other. The components are mounted on the cut structure before or after the last mentioned manufacturing step. Plastic bridges provide mechanical support

  necessary for the different conductive tracks.

  FIG. 2 represents, in top view, a control device according to the invention which comprises a housing 3 comprising a lower part of the housing 31 which serves as support for a cut structure 1 whose male pins 42 are only shown in a dashed line, parts of which can be seen leaving the housing 3. The lower housing part 31 contains a connector 4 comprising a part 41 for housing an associated socket. The lower part of the casing 31 is closed, by means of snap hooks 311, by a casing cover 32 from which a protective plate 324 is mainly visible. In two locations, the cut structure 1 comes out of the lower casing part 31 and

  is fixed to an external support 5 by means of screws 51.

  Figure 3 shows a side view of the control device of Figure 2 through the cutting line A-A. We see more particularly the realization in one

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  part of the male pins 42 with the cut structure 1. A pressure sensor 21 without housing, a filtering capacitor 22, an amplifier 23 without housing and other components 2 are mounted on the cut structure 1. The pressure sensor 21 can be formed by any pressure sensor, but in particular by a silicon pressure sensor which can still receive in its substrate another part of an electrical circuit. Such an integrated circuit comprising a pressure sensor 21 is then linked directly to the cut-out structure 1 in the form of an integrated circuit without a housing, as is

shown in Figure 3.

  Since the protection against the penetration of electromagnetic radiation reaching the electrical circuit of the control device is ensured by means of the flat areas of the cut structure, the housing of the control device is preferably made of plastic material. In this case, the lower part of the housing 31, including the housing part 41 of the connector 4, is for example obtained by injection around the cut structure 1. The lower part of the housing 31 is closed in a sealed manner against the water, and this in any way, by the housing cover 32 which is also made of plastic. In the embodiment, this connection is obtained by means of snap hooks 311, with a sealing ring 33 inserted between the housing cover 32 and the lower housing part 31, the sealing ring 33 being able to also be made of plastic and by injection on one

housing halves 31, 32.

  A membrane 322 is permanently fixed to the housing cover 32. The membrane 322 can for example be made of flexible plastic and can thus be produced by injection on an opening 321 of the housing cover 32. However, the membrane 322 can also be made in one piece with the housing cover 32. For this purpose, the housing cover 32 has an area which serves as a membrane 322 and which has a thickness that is thinner than the housing wall 323 of the housing cover 32. The membrane 322 must protect from influences from the surrounding environment and from corrosion the interior space of the control device and in particular the pressure sensor 21 and the electrical circuit. The membrane 322 is then waterproof and its connection to the housing cover 32 is also made waterproof. On the other hand, the membrane 322 is preferably slightly permeable to air, so that for example, a rise in pressure in the interior space of the control device which is due to a rise in temperature is compensated by means of a pressure balance with the

  surrounding medium via the membrane 322.

  This pressure equilibrium is then obtained in an interval

  significant time - for example of the order of minutes -

  compared to the duration of the significant pressure signals received. Thus, the pressure signals received are neither weakened nor distorted. The membrane 322 is then for example made of an elastic plastic material,

  such as silicone rubber.

  Preferably, the membrane 322 has, in its outer peripheral part, a hollow rib 3221 by means of which the membrane 322 can expand or retract within certain limits, in order to thus compensate for the stresses present in the membrane 322 which are due to temperatures which vary alternately or a pressure of the surrounding medium which varies. Therefore, there is exerted on the membrane 322 removed from its position a restoring force which is almost constant over its entire area apart, so that the sensitivity of the

  pressure sensor 21 is not influenced.

  Above the membrane 322 of FIG. 3 which is produced with a relatively large surface area and which therefore transmits a pressure signal particularly well to the pressure sensor 21, there is disposed a protection plate 324 which serves as protection against -vis waters

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  projection and prevents contact from occurring with the

membrane 322.

  FIG. 4 represents the fixing of the control device to the support 5 by the part 15 of the cut structure 1 which leaves the housing 3 and by means of a screw connection 51, while, thanks to this fixing, the potential of mass of the cut structure 1 is set to the potential of the support 5. If the control device according to the invention is used as a control device for triggering an airbag for lateral protection in a motor vehicle, the control device is then fixed in a vehicle door, on a support / element for holding the door. The assembly of the components 2 and of the pressure sensor 21 on the cut structure 1 can also be carried out in the lower part of the housing 31 already containing the cut structure 1, without cover of

housing 32.

  FIG. 5 represents a known control device, used to trigger retaining means in a vehicle, which comprises the components already known, except that the amplifier 23 with a housing, the pressure sensor 21 disposed on a support 211, the filtering capacitor 22 and the male pins 42 are connected to a conventional printed circuit board 6 in the form of independent folded components and that a sleeve 7, surrounding the pressure sensor 21 and comprising a membrane 322, makes it possible to produce a small volume for pressure transmission, since the volume of the interior space

  is too large for this pressure transmission.

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Claims (8)

  1. Control device, in particular for the triggering of retaining means in a vehicle, comprising a housing (3), which comprises a connector (4), and an electrical circuit which is arranged in the housing (3) and comprises a sensor pressure (21), characterized in that components (2, 21) of the electrical circuit are connected in an electrically conductive manner by means of a structure (1) cut from a metal strip (12), in that that the cut-out structure (1) contains male pins (42) of the connector (4) and in that an area located in the housing wall (323) is produced in the form of a membrane (322) used for the pressure transmission.   2. Control device according to claim 1, characterized in that the housing (3) is made of plastic, 3. Control device according to claim 1, characterized in that a housing part (41) of the connector (4), serving to receive an associated socket, and a part of the housing (3) are made in one piece, 4. Control device according to claim 1, characterized in that the zone produced in the form of a membrane (322) is formed in one piece with the housing (3) and has a thickness that is thinner than the housing wall (323) , 5. Control device according to claim 1, characterized in that the housing (3) has an opening (321) on which is disposed a membrane (322) of flexible plastic which is connected to the housing (3) in a way waterproof, 6. Control device according to claim 1, characterized in that the pressure sensor (21) is integrated and arranged on the cut structure (1) in the form of an integrated circuit without housing, 7. Control device according to claim 1, characterized in that a part (15) of the cut structure (1) passes out of the housing and in that the control device is fixed by this part (15) on a support (5), 8. Control device according to claim 1, characterized in that the cut structure (1) comprises flat areas (13) used for electromagnetic shielding.