FR2850615A1 - Seat assembly for vehicle, has sensor to emit signal when face of sensor is submissive to pressure field, and rigid unit including support portion situated near another face of sensor to exert reaction on part of latter face - Google Patents

Abstract

The assembly has a cushion support to receive an occupant generating a field pressure in a seat unit. A sensor (6) has a face oriented towards a face of the support to detecting a presence of occupant. The sensor emits a signal when the face is submissive to the pressure field. The seat unit has a rigid unit (15) with a support portion situated near another face of the sensor to exert a reaction on a part of the latter face.

Description

SEAT ELEMENT WITH PRESENCE SENSOR

  DETECTION DEVICE AND DEVICE FOR SUCH A SEAT ELEMENT.

  The present invention relates to seat elements having presence sensors, and detection devices for such seat elements.

  More particularly, the invention relates to a seat element comprising - a structure, - a padding carried by the structure, having a bearing surface for receiving an occupant generating a pressure field in the seat member in a direction d application, and - at least one presence sensor, having a first face oriented towards the support face and arranged to be subjected to the pressure field exerted by the occupant, and a second face opposite to the first face, this sensor being adapted to emit a signal when its first face is subjected to said pressure field.

  Such seat elements, such as seats or seat backs, are known and have sensors generally located on the surface in the seat element, directly under a soft covering cap, covering the padding and receiving the occupant. . An occupant seated in the seat generates a pressure field in the seat member, and thus applies a pressure on the presence sensors, so that a signal is emitted by the presence sensor, and this signal determines the presence of occupant 30 in the seat. The sensitivity of these sensors is however such that it is necessary to position them directly under the cap.

  This integration mode has the following drawbacks in particular: it degrades the comfort of the seat, it reduces the resistance in endurance of the cap of the seat element, and the sensor has a variable sensitivity depending on the nature of the seat cover. covering with which the seat element is covered.

  The present invention is intended to overcome these disadvantages.

  For this purpose, according to the invention, there is provided a seat element which, in addition to the features already mentioned, is characterized in that it comprises a rigid component comprising a bearing portion located near the second face of the seat. sensor and adapted to exert a reaction on at least a portion of the second face of the sensor, when said pressure field is generated in the seat member, the sensor being mounted in the seat member between the rigid component and the bearing face.

  With these arrangements, it is sufficient to apply a very low pressure on the sensor so that it generates a signal, regardless of the cap materials used. It is then possible to envisage moving the presence sensor away from the support surface, for example so as to place a heating sheet or the like directly under the cap, while avoiding interactions between said heating layer and the sensors, interactions which could harm the proper functioning of the system.

  In preferred embodiments of the invention, one or more of the following provisions may also be used: the sensor and the rigid component are included in the padding and the rigid component comprises an extended rigid member adapted to support the padding; the rigid component further comprises at least one point rigid element in contact with the padding, of which at least one dimension in a plane orthogonal to the direction of application of the pressure field at the level of the sensor is of less than 1 the extent of the sensor in this plane, so that the extended rigid element is between the sensor and the point rigid element; the sensor and the rigid component are included between the padding and the structure of the seat element, and the rigid component comprises an extended rigid element adapted to bear on the structure; the support portion of the rigid component comprises at least one rigid point element situated between the extended rigid element and the sensor and of which at least one dimension in a plane orthogonal to the direction of application of the pressure at the sensor is less than the extent of the sensor in this plane; - The seat member further comprises at least one lateral rigid element, arranged to frame the sensor in a direction orthogonal to the direction of application of the pressure field; The sensor comprises: a first layer, having an outer face of the first layer, intended to be subjected to the pressure exerted by an occupant, and an inner face of the first layer on which is mounted a first conductive element, and a second layer, having an internal second layer face placed facing the inner face of the first layer, and on which is mounted a second conductive element, facing the first conductive element 30, and an outer face of the second layer, the The sensor is adapted so that the pressure field generated by the occupant is exerted on the outer face of the first layer and the reaction is exerted on the outer face of the second layer and these two pressure fields bring the two conductive elements into contact with each other. the seat element comprises at least two sensors, included between two flexible sheets to form a sheet of sensors; a common rigid element constitutes the support portion of the rigid component of at least two sensors; the sensors are separated by at least one intermediate stiff element mounted between said sensors; the sensor sheet further comprises a flexible element located near the outer face of the first layer, and arranged to distribute the pressure exerted by the occupant over a large area of the first face of the sensor.

  According to another aspect, the invention relates to a detection device for a seat element comprising: at least one presence sensor, having a first face, and a second face opposite to the first face, this sensor being adapted to emit a signal 20 when its first face is subjected to a pressure field, and - at least one rigid component comprising a bearing portion located near the second face of the sensor and adapted to exert a reaction on at least a portion of the second face of the sensor, when said first face is subjected to the pressure field.

  Other aspects, objects and advantages of the invention will appear on reading the description of several of its embodiments given as non-limiting examples.

  The invention will also be better understood with the aid of the drawings, in which: FIG. 1 represents a vehicle seat equipped with presence sensors, FIG. 2 represents a sheet of sensors, FIGS. 3a, 3b and 3c. represent a sensor in use, seen in section along the line III-III of Figure 2, - Figure 4 shows a sensor for a seat according to the invention - Figure 5 shows a second example of a sensor for a seat according to the invention; FIG. 6 shows a sheet of sensors, according to a third example, intended to be mounted in a seat element according to the invention; FIG. 7 represents a seat element according to the invention according to a fourth example, and - Figure 8 shows a seat member according to the invention, according to a fifth example.

  In the different figures, the same references designate identical or similar elements.

  Figure 1 shows a seat, comprising a seat 1 seat on which an occupant 2 can take place. It should be noted that the invention described herein is not limited to seat seats, and applies to any other seat element capable of being provided with a presence sensor, such as for example a seat back , a seat headrest, an armrest or other.

  The seat 1 comprises on its upper part a flexible covering cap 3, made of variable type materials according to the seat in question (for example textile, leather, etc.) and covering a lining 4 such as foam padding. synthetic or otherwise, which is supported by a resistant structure. This resistant structure comprises, for example, a rigid reinforcement (not shown) on which is mounted an elastic suspension sheet 21, made for example of metal son, which carries the lining 4.

  Directly under the cap 3, or placed inside the lining 4, are one or more layers of presence sensors. The presence sensors are traditionally arranged in such plies 5, of thickness less than one millimeter, as shown in FIG. 2, but could equally well be individually arranged at different locations in the seat 1.

  FIG. 2 represents such a layer 5 of sensors, viewed from above in FIG. 1, and provided with a plurality of sensors 6, for example six in number, and which can in particular each have a flattened cylindrical shape whose faces are substantially parallel to each other. the bearing face of the seat element (in this case, the upper face).

  In the example shown here, these sensors are interconnected by a first electrical wire 7, connected to the pole plus of an electric generator, and by a second electrical wire 8 connected to the minus pole of the electric generator. Either of these wires can also be connected to an ohmmeter. At rest, when not stressed, the presence sensors 6 have a high resistance, so that no current can pass through these sensors.

  The principle of operation of these sensors is shown in a sectional view, along the line III-III, 25 in Figures 3a to 3c. These figures represent a particular type of sensor, but other types of sensors could be used according to the invention, including the type for contacting conductive elements under the action of a pressure.

  Figure 3a shows a sensor 6 at rest. This sensor is for example of cylindrical shape, or other, and of thickness between about 0.1 mm and 0.5 mm. It comprises among other things: a first layer 9, constituted for example by a flexible synthetic material, intended to receive on its outer face 29, of extension S e, a pressure in a direction generally normal to the surface of this first layer 9, and connected to the envelope 17 of the sheet 5 of sensors, and further having an inner face 24, oriented towards the inside of the sensor 6, of extension Sli, - a second layer 10 , constituted for example by a flexible synthetic material, having an external face of extension S2e, and an inner face of extension S2i, oriented towards the inside of the sensor 6, and of an intermediate layer 11, consisting of example of a flexible synthetic material, placed between the first 9 and second 10 layers; this intermediate layer may for example be annular and of a smaller extent than the first and second layers so that it defines a covering space 27 in which both the first 9 and second 10 layers are in contact with the intermediate layer 11, and a free internal space 12 in which the internal faces of the first layer and the second layer 24, 26 are not in contact with the intermediate layer and are normally spaced apart from each other.

  The inner faces of the first and second layers 24, 26 are respectively provided with a first 13 and a second 14 conductor elements at the free internal space. These first 13 and second 14 conductive elements, respective extents Si, and S2c are for example of extension less than or equal to the extent of the free internal space 12. They are also respectively connected to the first 7 and the second 8 electric wires.

  For example, in the case of a cylindrical sensor, the sensor 6 is constituted by the stack of a first cylindrical layer 9, the intermediate layer 11, in the form of a ring, and the second cylindrical layer 35 so that that the hollow space in the center of the ring of the intermediate layer 11 constitutes the free internal space 12, also cylindrical in shape, and whose circular faces are formed in whole or in part by the first 13 and second 14 conductive elements. Of course, any form of sensor for matching at a given distance two conductive elements, may be used within the scope of the invention.

  As shown in FIG. 3b, when a high pressure is exerted on the sensor 6, the sensor 6 deforms and the free interior space 12 is compressed until the first 13 and second 14 conductive elements enter into position. contact, which allows a current to flow between the first 7 and the second 8 electrical wire. The ohmmeter then detects a drop in resistance of the web, which means that the seat is occupied.

  Nevertheless, and as shown in FIG. 3c, when a too weak pressure is exerted on the sensor 6, the first layer 9 is not sufficiently deformed to compensate for the displacement or the deformations of the second layer 10, so that the first 13 and second 14 conductive elements do not come into contact, and no current passes. This phenomenon is common among sensors of the prior art.

  In order to obtain a high degree of sensitivity of the sensor 6, even when a low pressure is applied to it, the seat element consists, in addition to the sensor 6 previously described, of a rigid component 15 placed near the second 10. This rigid component 15 is for example mounted on the padding 4 of the seat or connected to the structure of the seat member, as explained later. Thus, when pressure is exerted on the first layer 9 of the sensor 6, the displacement of the sensor 6 in the direction of pressure brings the second layer of the sensor 6 into contact with the rigid component 15, which is not very mobile, which applies pressure reaction on the second layer 10 of the sensor, in a direction opposite to the direction of application of the first pressure, so that the first 13 and second 14 conductive elements are brought into contact.

  In the first example of FIG. 4, the rigid component 15 comprises an extended rigid element 16, for example having a cylindrical shape of radius approximately equal to the radius of the sensor 6, but which may be less extensive, or a plate of non-cylindrical shape . This extended rigid member 16 is mounted near the second layer 10 and can be placed in or under the padding 4. The rigid component 15 may furthermore comprise a point-like rigid element 18a located, in this first embodiment, between the extended rigid element 16 and the second layer 10 of the sensor 6, and having, for example, a domed, thick shape. This pointless rigid element 18a can optionally be fixed to the extended rigid element 16. Optionally, the extended rigid elements 16 and 20 punctual 18a are constituted by a single piece. These rigid elements can be made from hard plastic materials, or even metal.

  Figure 5 shows a second embodiment of a portion of a seat member according to the invention. In this embodiment, the rigid component 15 comprises, in addition to the extended rigid element 16 and the pointal rigid element 18a, a lateral element 20 placed between the sensor 6 and the edge of the sensor web 5.

  Fig. 6 shows a third embodiment of the invention. FIG. 6 more specifically represents two sensors 6 integrated side by side in a sheet of sensors. Each sensor 6 has a flexible element 19, optional, located near the first layer 9 of the sensor 6, and for homogenizing the pressure on said cells. The other constituent elements of the sensor 6 located on the left of FIG. 6 have already been described in FIG. 5. The right-hand sensor in FIG. 6 has a different rigid element 18b, for example spherical, or cylindrical in one direction. perpendicular to the plane of the section of Figure 6, and not necessarily located opposite the center of the interior space 12. Thus, any type of rigid point element 18a, 18b is likely to be used.

  The two sensors are further separated by a rigid intermediate element 20, directly in contact with the lateral face 23 of the sensors, and for example made of the same material as the rigid elements extended 16 or punctual 18a, 18b. This intermediate rigid element is optionally placed in the ply 5 and is intended to limit the overall pressure on the ply of sensors 5.

  It may well be imagined that the sensor further comprises rigid lateral elements 20, as shown in FIG. 5, in which case the intermediate rigid element 20 and the lateral rigid element 20 of FIG. 5 can be constituted by a same element.

  In this exemplary embodiment, a point-like rigid element 18b may, for example, extend indifferently under a single sensor 6, or under several sensors. For example, the rigid point element 18b on the right of FIG. 25 is cylindrical and extends to another sensor 6 (not visible) located behind the sensor shown on the right of FIG. 6.

  Figure 7 shows a fourth embodiment of the invention. In this example, besides the sensors 6, the flexible element 19, optional, and the intermediate rigid element 20, also optional, all already described, the seat element has an extended rigid element 16, as described above, but having the particularity of extending between the point rigid elements 18a, 18b and the second sensor layer 10. Likewise, the point elements 18a, 18b are not necessarily centered on the sensors 6, or on the free internal spaces 12 of the sensors 6.

  Figure 7 further shows the positioning of the sensor web in the seat element between the hood 3 and the suspension web 21 of the seat element. Of course, such a positioning of a sensor web is not specific to this embodiment, but is valid for all the embodiments previously presented.

  Of course, all or part of the sensor web may be overmoulded preferably flexible plastic material, or optionally included in the foam forming the padding of the seat member.

  It is possible to dispense with fixing point rigid elements 18a, 18b in the padding of the seat element, advantageously taking advantage of the discontinuities offered by the structure of the seat 21, as shown in FIG. 8. By placing the sheet of With regard to such discontinuities, for example by adapting the distance between the sensors to the gap existing between two parallel wires of the suspension ply 21, it is possible to use the local discontinuities of the seat structure 21 as rigid point elements 18b. of the sensor. It is not necessary, however, that the sensors are located very precisely vis-à-vis the suspension web.

  A seat element is thus provided with presence sensors, for example arranged in a sheet, and sensitive to very small pressure gradients inside the seat.

Claims (12)

  1. Seat element (1) comprising - a structure (21), - a padding (4) carried by the structure 5 (21), having a bearing face (28) intended to receive an occupant generating a pressure field in the seat member (1) in an application direction, and - at least one presence sensor (6), having a first face (29) facing the support surface (28) and arranged to be subjected to the pressure field exerted by the occupant, and a second face (25) opposite to the first face (29), this sensor being adapted to emit a signal when its first face (29) is subjected to said pressure field, characterized in that the seat element (1) comprises a rigid component (15), comprising a bearing portion located near the second face (25) of the sensor (6) and adapted to exert a reaction on at least one part of the second face (25) of the sensor (6), when said pressure field is generated in the ment seat, the sensor (6) being mounted in the seat member between the rigid component (15) and the bearing face (28).   The seat element according to claim 1, wherein the sensor (6) and the rigid component (15) are included in the padding (4) and wherein the rigid component (15) comprises an extended rigid member (16). adapted to take support on padding (4).   The seat element according to claim 2, wherein the rigid component (15) further comprises at least one point rigid element (18a, 18b) in contact with the padding (4), at least one dimension of which in a plane orthogonal to the direction of application of the pressure field at the sensor (6) is of a range less than the extent of the sensor (6) in this plane, so that the extended rigid element (16) is included between the sensor (6) and the rigid point element (18a, 18b).   The seat element according to claim 1, wherein the sensor (6) and the rigid component (15) are included between the padding (4) and the structure (21) of the seat element, and wherein the rigid component (15) comprises an extended rigid element (16) adapted to bear on the structure (21).   Seat element according to any one of claims 2, 3 or 4, wherein the bearing portion of the rigid component (15) comprises at least one rigid point element (18a, 18b), located between the element extended rigid (16) and the sensor (6) and of which at least one dimension in a plane orthogonal to the direction of application of the pressure at the sensor (6) is of smaller extent than the extent of the sensor ( 6) in this plan.   6. Seat element according to any one of the preceding claims, further comprising at least one lateral rigid element (20), arranged to frame the sensor (6) in a direction orthogonal to the direction of application of the pressure field. .   Seat element according to any one of the preceding claims, in which the sensor (6) comprises: a first layer (9) having an outer face of a first layer (29) intended to be subjected to the pressure exerted by an occupant, and an inner face (24) of first layer on which is mounted a first conductive element (13), and - a second layer (10), having an inner face (26) of second layer placed opposite the inner face of first layer (9), and on which is mounted a second conductive element (14), facing the first conductive element (13), and an outer surface (25) of second layer, the sensor being arranged so that the pressure field generated by the occupant is exerted on the outer face of the first layer (9) and the reaction is exerted on the outer face of the second layer and these two pressure fields bring the two conductive elements (13, 14) in contact.   8. Seat element according to any one of the preceding claims comprising at least two sensors (6), included between two flexible sheets to form a sheet (5) of sensors.   9. Seat element according to claim 8, wherein a common rigid element constitutes the bearing portion of the rigid component (15) of at least two sensors (6).   10. Seat element according to any one of claims 8 and 9, wherein the sensors (6) are separated by at least one interleaved rigid element (20) mounted between said sensors (6).   Seat element according to any one of claims 8 to 10, wherein the sensor web (5) further comprises a flexible element (19) located near the outer face of the first layer (9), and arranged to distribute the pressure exerted by the occupant over a large area of the first face of the sensor (6).   12. Detection device for a seat element (1) according to claim 1, comprising: - at least one presence sensor (6) having a first face (23) and a second face (25) opposite to the first face (23), this sensor being adapted to emit a signal when its first face (23) is subjected to a pressure field, and - at least one rigid component (15) comprising a bearing portion located near the second face (25) of the sensor (6) and adapted to exert a reaction on at least a portion of the second face (25) of the sensor (6), when said first face is subjected to the pressure field.