Patent Publication Number: US-11654951-B2

Title: Vehicle steering wheel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/774,473, filed May 8, 2018, which is a National Stage of International Application No. PCT/EP2016/077447, filed on Nov. 11, 2016, which claims priority to French Patent Application FR 1560778, filed on Nov. 11, 2015, the disclosures of which applications are incorporated herein by reference. 
    
    
     FIELD 
     The present invention relates in general to a vehicle steering wheel mounted on a motor vehicle and equipped with presence sensors to detect whether the driver is holding or has let go of the steering wheel, so as to transmit an alarm, for example, in the latter case. 
     In the prior art, steering wheels are known with a hoop equipped with such presence sensors, such as that disclosed by document US 2004267422. But this system has the particular drawback of proposing several sensors that are difficult to position on the steering wheel and hold in place during manufacture. Moreover, bearing in mind the fact that these presence sensors must not be visible, they must therefore be arranged beneath the outer surface of the hoop and so must be positioned either beneath a sheath (of leather for example), embedded or even overmolded with a plastics material (such as polyurethane, for example). Consequently, this plurality of presence sensors is a drawback for the manufacture of the steering wheel. 
     One object of the present invention is to resolve the drawbacks of the above-mentioned document of the prior art and in particular, firstly, to propose a vehicle steering wheel that has several presence sensors, but is of simplified manufacture. 
     For this, a first aspect of the invention concerns a vehicle steering wheel comprising: 
     a hoop, 
     a plurality of presence sensors, each one arranged: 
     so as to define on the hoop one detection zone among a plurality of discrete detection zones, and 
     so as to detect a proximity and/or contact between a user&#39;s limb and said detection zone, 
     an outer sheath covering the plurality of presence sensors, characterized in that said plurality of presence sensors is mounted on the same support, 
     wherein the support with the presence sensors forms a detection layer comprising the support formed by an electrical insulator such as polyethylene supporting on a first face the presence sensors formed for example with a polyamide yarn covered at least with nickel, and supporting on a second face at least one grounding electrically conductive film or fabric formed, for example with a polyamide yarn coated at least with nickel, and in which the detection layer comprises a grounding electrically conductive film or fabric for a plurality of presence sensors. 
     In other words, the grounding electrically conductive film or fabric is common, or shared, for a plurality of presence sensors. 
     The presence sensors and/or grounding conductive film are in the form of a sheet or film and can be made of woven or non-woven fabric. However, the detection layer formed is flexible (it can be wound round the hoop and even deform in order to stretch or compress so as not to be visible once it is covered, for example, by leather). Moreover, the grounding conductive film or fabric (also referred to as a guard or shield), single and common to the sensors, simplifies the construction of the detection layer, limits the number of connections to the vehicle and simplifies the electronics to which it is connected. In fact, one grounding connection suffices for all of the presence sensors. This avoids the need to run a multitude of grounding electrical conductors in the hub, and/or beneath the sheath. Moreover, there is no need for the electronics connected to the grounding conductor to be multiplexed because the same grounding element is used for all of the sensors. The steering wheel and the associated electronics are therefore simpler. 
     Advantageously, the support comprises one grounding electrically conductive film or fabric. 
     Advantageously, the outer sheath is stitched with at least one seam that extends around at least part of the hoop. 
     Advantageously, at least one of said presence sensors is arranged facing at least part of the seam of the outer sheath, so as to define a detection zone that encompasses at least part of said at least one seam and that extends on either side of said at least one seam, in a transverse direction to said at least one seam. 
     The steering wheel according to the above embodiment (with a sewn outer sheath that covers the hoop) comprises several sensors but these are integral with one and the same support, which simplifies manipulation and holding in place during manufacture. Moreover, one of the presence sensors faces the seam of the outer sheath that runs around the hoop. 
     Such a seam connects the two longitudinal edges of the outer sheath together, in order to secure the sheath on the hoop. In fact, before fitting onto the steering wheel, the outer sheath is typically a piece of material generally rectangular in shape. This rectangle has two longitudinal edges, the length of which is substantially that of the inner perimeter of the hoop (since the seam is on the inside of the hoop, facing the hub), that are then stitched together, edge-to-edge for example. Furthermore, this rectangle has two lateral edges, the length of which is substantially that of the perimeter of a section of the hoop in a plane containing the axis of a steering column. As the seam is located on the inside of the hoop, the outer sheath is pre-positioned round the outside of the hoop and then folded inwards so that the lateral edges face the inside of the hoop. 
     Coming back to the presence sensor facing the seam of the outer sheath, it extends along the seam and also on either side thereof and enables detection of a proximity and/or a contact with the detection zone encompassing the seam and running along either of this seam. In other words, it is possible to detect with a single sensor whether the driver is touching the steering wheel on an inner portion of the hoop (a portion facing the hub). This embodiment thus also improves manufacture by simplifying the overall architecture: just one presence sensor is sufficient and enables detection of a proximity and/or a contact on the seam and on either side thereof (in relation to the longitudinal direction of the seam). 
     In comparison to a steering wheel comprising a presence sensor that surrounds the hoop, with a join zone (where the edges of the sensor meet without touching) arranged at the seam where detection is impossible due to the space between the edges of the presence sensor, the invention offers a detection advantage at the seam, with only one presence sensor. In other words, the invention utilizes the space between two detection zones to position the join zone. This optimizes the coverage of the detection zone. 
     Advantageously, the presence sensor arranged facing at least part of the seam has at least one edge that is always on the same side of the seam. This sensor can, for example, have a generally rectangular shape. One or two sides of this sensor can be substantially parallel to the seam. This optimizes the cutting plane of the sensor and at the same time of the sensor support while retaining total sensitivity at the seam. As the seam is located on the inside of the hoop, the sensor support is pre-positioned on the inside, the front face or the rear face of the hoop and then folded back so that the side edges face the outside, front or rear of the hoop but not the inside. In other words, the sensor support is positioned inversely or turned by 90° in relation to the outer sheath since the latter closes on the inside the hoop, at the seam. 
     Advantageously, the sensors are of the capacitive type. 
     Advantageously, said at least one seam only passes through the outer sheath. This embodiment means that the presence sensor that is facing the seam is not affected. 
     Another aspect of the invention relates to a vehicle steering wheel comprising: 
     a hoop, 
     a plurality of presence sensors, each one arranged: 
     so as to define on the hoop one detection zone among a plurality of discrete detection zones, and 
     so as to detect a proximity and/or a contact between a user&#39;s limb and said detection zone, 
     a hub, connected to the hoop by at least one spoke, 
     an outer skin made of a plastics material, covering at least the plurality of presence sensors, 
     characterized in that said plurality of presence sensors is mounted on one support, 
     in which the support with the presence sensors forms a detection layer comprising the support formed by an electrical insulator such as polyethylene supporting on a first face the presence sensors formed for example with a polyamide yarn covered at least with nickel, and supporting on a second face at least one grounding electrically conductive film or fabric formed, for example with a polyamide yarn coated at least with nickel, and in which the detection layer comprises a grounding electrically conductive film or fabric for a plurality of presence sensors. 
     In other words, the grounding electrically conductive film or fabric is common, or shared, for the plurality of presence sensors. 
     The presence sensors and/or the grounding conductive film are in the form of a sheet or film and can be made of woven or non-woven materials. However, the detection layer formed is flexible (it can be wound round the hoop and even deform so as to stretch or compress so as to be visible once it is covered, for example, by leather). Moreover, the grounding conductive film or fabric (also referred to as a guard or shield) single and common to the sensors simplifies the construction of the detection layer so as to limit the number of connections to the vehicle and simplifies the electronics to which it is connected. In fact, one grounding connection suffices for all of the presence sensors. This avoids the need to run a multitude of grounding electrical conductors in the hub, and/or beneath the sheath. Moreover, there is no need for the electronics connected to the grounding conductor to be multiplexed because the same grounding element is used for all of the sensors. The steering wheel and the associated electronics are therefore simpler. 
     Advantageously, the support comprises one grounding electrically conductive film or fabric. 
     Advantageously, at least one of said presence sensors is arranged around at least part of an inner perimeter of the hoop that is facing the hub, so as to define a detection zone that encompasses at least part of said at least one inner perimeter and that extends on either side of said at least one inner perimeter, in a transverse direction to said at least one inner perimeter. 
     The steering wheel according to the above embodiment (with a smooth and continuous outer skin, or with no seam around the hoop and that covers the hoop and overmolding or embedding the plurality of presence sensors) comprises several sensors but these are integral with one and the same support, which simplifies manipulation and holding in place during manufacture. Moreover, one of the presence sensors is arranged at the inner perimeter of the hoop (the part facing the hub) and then extends around at least part of this inner perimeter and also on either side, which allows a proximity and/or a contact between a detection zone that encompasses the inner perimeter, and extends on either side of this inner perimeter. In other words, it is possible to detect with a single sensor whether the driver is touching the steering wheel on an inner portion of the hoop (a portion facing the hub). This embodiment thus also improves manufacture by simplifying the overall architecture: just one presence sensor is sufficient and enables detection of a proximity and/or a contact on the inner perimeter and on either side thereof (in relation to the longitudinal direction of the inner perimeter). 
     Thus, the invention provides a detection for a steering wheel with a sewn sheath or seamless sheath in zones that do not normally have presence detection. 
     Advantageously, the vehicle steering wheel comprises: 
     a first presence sensor arranged to detect a proximity and/or a contact between a user&#39;s limb and a first detection zone arranged on an inner portion of the hoop, 
     a second presence sensor arranged to detect a proximity and/or a contact between a user&#39;s limb and a second detection zone arranged on a first half of an outer portion of the hoop, 
     a third presence sensor arranged to detect a proximity and/or a contact between a user&#39;s limb and a third detection zone arranged on a second half of an outer portion of the hoop. The steering wheel according to this embodiment makes it possible to differentiate the user&#39;s grip. If the latter touches the steering wheel on an inner portion of the hoop, the first presence sensor will detect it. If the user touches the steering wheel solely with his right hand on the outside of the hoop, one of the second or third presence sensors will detect it. Lastly, if the driver touches the steering wheel solely with his left hand on the outside of the hoop, the other of the second or third presence sensors will detect it. Clearly, the detection can take into account the rotation of the steering wheel in order to distinguish the left from the right. 
     Advantageously, the vehicle steering wheel comprises at least one spoke to connect the hoop to a hub, and the first presence sensor surrounds said at least one spoke and/or comprises a cutout to surround said at least one spoke, and covers at least two portions of the inner perimeter separated by said at least one spoke. 
     Advantageously, the first presence sensor covers at least partly each of the portions of the inner perimeter separated by said at least one spoke. 
     Advantageously, each presence sensor among the plurality of presence sensors is arranged to detect continuously a proximity and/or a contact between a user&#39;s limb and its respective detection zone. 
     Advantageously, the detection layer and/or the support with the presence sensors has an elongated and flat form before being placed around the hoop, with two longitudinal edges and two lateral edges. 
     Advantageously, the steering wheel hoop substantially forms a torus, obtained by rotating a section of the hoop about a circle of radius R. 
     Advantageously, the longitudinal edges are of a length that is substantially equal to a perimeter of the circle of radius R. 
     Advantageously, the lateral edges are of a length that is substantially equal to a perimeter of the section of the hoop (in a section or cut through a plane containing the axis of rotation of the steering wheel, or hub, or steering column). 
     Advantageously, the detection layer has an elongated form, with two longitudinal edges each connecting two ends lengthwise, and in which the plurality of presence sensors and said at least one grounding electrically conductive film or fabric each has a connection portion, and in which the connection portions are all arranged along the same longitudinal edge. This embodiment allows simplification of the electrical connection of the detection layer, with all of the connection portions on the same side of the detection layer. Moreover, as there is only one grounding film or fabric common to all of the sensors, its connection is easy to make along one longitudinal edge, since the surface of the common grounding film or fabric is necessarily tangent to or common with this longitudinal edge. It is therefore easier to make the connections of the layer of the steering wheel according to the invention with the vehicle&#39;s onboard network. A connection portion is a sensor portion, i.e. formed of the same material as that of the sensor, this allows the detection layer not to be made overly thick by using another element. 
     Advantageously, the connection portions are positioned in a connection zone between the hoop and at least one spoke. Preferably the connection zone is located at the bottom of the steering wheel, alternatively called the six o&#39;clock zone. This makes it possible to optimize the position of the connection zones in relation to the detection zones. 
     Advantageously, the connection portion of the second sensor and the connection portion of the third sensor are arranged on either side of the first sensor. 
     Advantageously, the connection portion of the first sensor is arranged between the second sensor and the third sensor. 
     Advantageously, the vehicle steering wheel comprises at least one spoke connecting the hoop to a hub, with a first lateral edge of said at least one spoke connecting the hoop with a first radius of curvature and a second lateral edge of said at least one spoke connecting the hoop to a second radius of curvature greater than the first radius of curvature, the support and at least one of the presence sensors covers a portion of said at least one spoke, 
     and the support and said at least one of the sensors have a cutout offset towards the first lateral edge, in relation to a width of said at least one spoke. This embodiment facilitates the cutout of the template or flat form of the detection layer, by bringing the cutout of the lateral edge that has the smallest radius of curvature closer. This also facilitates the sheathing of the template on the steering wheel and limits the risk of the formation of creases. 
     Another aspect of the invention relates to a vehicle steering wheel comprising: 
     a hoop, 
     a plurality of presence sensors, each arranged: 
     so as to define on the hoop a detection zone among a plurality of discrete detection zones, and 
     so as to detect a proximity and/or a contact between a user&#39;s limb and said detection zone, 
     an outer sheath covering the plurality of presence sensors and stitched with at least one seam that extends around at least part of the hoop, characterized in that said plurality of presence sensors is mounted on the same support, and in that at least one of said presence sensors is arranged facing at least part of the seam of the outer sheath, so as to define a detection zone that encompasses at least part of said at least one seam and that extends from either side of said at least one seam, in a transverse direction to said at least one seam. 
     The steering wheel according to the above embodiment (with a stitched outer sheath that covers the hoop) comprises several sensors but these are integral with one and the same support, which simplifies manipulation and holding in place during manufacture. Moreover, one of the presence sensors faces the seam of the outer sheath that runs the around the hoop. 
     Such a seam connects the two longitudinal edges of the outer sheath, in order to secure the sheath on the hoop. In fact, before fitting onto the steering wheel, the outer sheath is typically a piece of material usually rectangular in shape. This rectangle has two longitudinal edges, the length of which is substantially that of the inner perimeter of the hoop (since the seam is on the inside of the hoop, facing the hub), that are then stitched together, edge-to-edge for example. Furthermore, this rectangle has two lateral edges, the length of which is substantially that of the perimeter of a section of the hoop in a plane containing the axis of a steering column. 
     Coming back to the presence sensor facing the seam of the outer sheath, it extends along the seam and also on either side thereof and enables detection of a proximity and/or a contact with a detection zone encompassing the seam and running along either side of this seam. In other words, it is possible to detect with a single sensor whether the driver is touching the steering wheel on an inner portion of the hoop (a portion facing the hub). This embodiment thus also improves manufacture by simplifying the overall architecture: just one presence sensor is sufficient and enables detection of a proximity and/or a contact on the seam and on either side thereof (in relation to the longitudinal direction of the seam). 
     In comparison to a steering wheel comprising a presence sensor that surrounds the hoop, with a join zone (where the edges of the sensor meet without touching) arranged at the seam where detection is impossible due to the space between the edges of the presence sensor, the invention offers a detection advantage at the seam, with only one presence sensor. In other words, the invention utilizes the space between two detection zones in order to position the join zone. This optimizes the coverage of the detection zone. 
     Advantageously, the sensors are of the capacitive type. 
     Advantageously, said at least one seam only passes through the outer sheath. This embodiment means that the presence sensor that is facing the seam is not affected. 
     Another aspect of the invention concerns a vehicle steering wheel comprising: 
     a hoop, 
     a plurality of presence sensors, each one arranged: 
     so as to define on the hoop a detection zone among a plurality of discrete detection zones, and 
     so as to detect a proximity and/or a contact between a user&#39;s limb and said detection zone, 
     a hub, connected to the hoop by at least one spoke, 
     an outer skin made of a plastic material, covering at least the plurality of presence sensors, 
     characterized in that said plurality of presence sensors is mounted on one support, 
     and in that said plurality of presence sensors is arranged around at least part of an inner perimeter of the hoop that is facing the hub, so as to define a detection zone that encompasses at least part of said at least one inner perimeter and that extends on either side of said at least one inner perimeter, in a transverse direction to said at least one inner perimeter. 
     The steering wheel according to the above embodiment (with a smooth and continuous outer skin, or with no seam around the hoop and that covers the hoop and overmolding or embedding the plurality of presence sensors) comprises several sensors but these are integral with one and the same support, which simplifies manipulation and holding in place during manufacture. Moreover, one of the presence sensors is arranged at the inner perimeter of the hoop (the part facing the hub) and then extends around at least part of this inner perimeter and also on either side, which allows a proximity and/or a contact between a detection zone that encompasses the inner perimeter, and extends on either side of this inner perimeter. In other words, it is possible to detect with a single sensor whether the driver is touching the steering wheel on an inner portion of the hoop (a portion facing the hub). This embodiment thus also improves manufacture by simplifying the overall architecture: just one presence sensor is sufficient and enables detection of a proximity and/or a contact on the inner perimeter and on either side thereof (in relation to the longitudinal direction of the inner perimeter). 
     Thus, the invention provides a detection for a steering wheel with a sewn sheath or seamless sheath in zones that do not normally have presence detection. 
     Clearly, all of the above independent aspects can be combined together to obtain a particular embodiment of the invention. 
     Another aspect of the invention concerns a motor vehicle comprising a steering wheel according to the preceding aspects. 
    
    
     
       Further features and advantages of the present invention will emerge more clearly from the following detailed description of an embodiment of the invention given by way of non-limiting example and illustrated by the accompanying drawings, in which: 
         FIG.  1    represents a front view of a vehicle steering wheel according to the present invention, with three detection zones of proximity and/or contact between a user&#39;s limb and the hoop; 
         FIG.  2    represents a section of the vehicle steering wheel in  FIG.  1    along axis II-II; 
         FIG.  3    represents a detail of the section shown in  FIG.  2   ; 
         FIG.  4    represents a first embodiment of a detection layer defining the three detection zones in  FIG.  1   ; 
         FIG.  5    represents an alternative of the detection layer in  FIG.  4   . 
     
    
    
       FIG.  1    represents a vehicle steering wheel comprising a hoop  10 , a hub  30 , connected to the hoop  10  by three spokes  21 ,  22 ,  23 . According to the invention, the steering wheel comprises a plurality of presence sensors  41 ,  42 ,  43  (visible in  FIG.  3    arranged beneath an outer sheath  16  (visible in  FIG.  2   , and of leather for example). 
     During manufacture, the outer sheath  16  is placed on the steering wheel and in particular on the hoop  10 , then sewn onto itself with at least one seam  15  that extends around the hoop  10  and is visible in  FIG.  2   . 
     Each presence sensor of the plurality of presence sensors  41 ,  42 ,  43  defines a detection zone  11 ,  12  and  13  of proximity and/or contact between a user&#39;s limb and the hoop  10 . As shown in  FIG.  1   , the detection zone  11  is located on the inner portion of the hoop  10 , i.e. on its portion facing the hub  30 . This means that the detection zone  11  encompasses the seam  15  of the outer sheath  16 , and also extends either side of the seam  15  to cover the entire inner portion of the hoop  10  facing the hub  30 , as shown in  FIG.  2   . 
       FIG.  2    is a section along axis II-II represented in  FIG.  1   , showing the detection layer  40  that is beneath the outer sheath  16 . This detection layer  40  comprises a support on which the presence sensors  41 ,  42  and  43  are mounted, as shown in  FIG.  3    for the presence sensor  41 . 
       FIG.  2    shows on the upper section of the hoop  10  that the detection layer  40  is wound round the hoop  10 , with a join that is located at around 3 o&#39;clock, i.e. opposite the driver. This section, surrounded by zone III is shown in further detail in  FIG.  3   . For a closure at around 3 o&#39;clock, the layer  40  is pre-positioned during its assembly at around 9 o&#39;clock (i.e. on the front face of the steering wheel) then the lateral edges are folded towards the back of the steering wheel, at 3 o&#39;clock. The initial position of the layer  40  can vary as long as the join lies between 9 o&#39;clock and 3 o&#39;clock, i.e. in the top part of  FIG.  3    and is not therefore located in the inner area of the hoop. 
     In other words, the join zone where the longitudinal edges of the detection layer are facing one another is not beneath the seam  15  as is usually the case when elements are sheathed on the hoop of a steering wheel. This join zone is angularly offset, which makes it possible to have only one presence sensor  41  in order to define one detection zone  11 , which is continuous. The embodiment according to general knowledge, with a join zone beneath the seam, would necessarily create, beneath the seam, a zone without detection. Note that the edges of the detection layer  40  do not touch, or that there is no electrical contact between these edges. 
     Lastly,  FIG.  2    shows, at the connection point of spoke  21  with the hoop  10 , that the detection layer  40  covers part of the spoke  21 . Due to the connecting radii between the spokes  21 ,  22 ,  23 , cutouts can be provided in the detection layer  40  for these spoke portions to be covered by the same template. If, as for the spoke  22 , there are two different connecting radii R 1  and R 2 , it is advantageous to provide the cutout on the side of the smallest radius, in order to limit the folds in the detection layer  40  during manufacture. For example, the cutout may be made at line  47  shown in  FIG.  1   , which is closer to radius R 1  than radius R 2 , in the sense of the width of the spoke  22 . Preferably, the cutout is made on a part of the detection layer  40  that is at the back of the steering wheel, on the face opposite the driver. 
       FIG.  4    represents a first embodiment of a detection layer  40 . This comprises all of the presence sensors  41 ,  42 ,  43 , a grounding film or fabrics  44 , and the support (not visible) arranged between the presence sensors  41 ,  42 ,  43 , and the grounding film or fabrics  44 . Typically, the presence sensors  41 ,  42 ,  43 , and the grounding film or fabrics  44  are sheets or films or fabrics comprising at least one polyamide yarn covered at least partially with nickel. In other words, the presence sensors  41 ,  42 ,  43  are capacitive sensors, with the detection layer  40  forming a sandwich or composite to this effect. The support is therefore an electrical insulator and can be made of foamed polyethylene for example. In this FIG. and  FIG.  5   , the future position of the seam  15  is represented by the dot-dash line  46 . As shown, the sensor  41  has a generally rectangular shape of which the long sides are substantially parallel to the seam  15 . Thus the long sides are always on the same side of the seam  15 . The cutting plane of the sensor  41  is thus optimized since there is no wastage on cutting the latter. The seam being located on the inside of the hoop, the sensor support is pre-positioned on the inside of the hoop and then folded outwards so that the lateral edges face the outside of the hoop. In other words, the sensor support is positioned inversely in relation to the outer sheath since it closes on the inside of the hoop whereas the sensor support closes on the outside of the hoop 
     The presence sensors  41 ,  42 ,  43  and the grounding film or fabrics  44  must therefore be connected electrically, and in zone  45  portions are provided to connect to a vehicle onboard network. In order to simplify assembly, all of the connection portions are arranged on the same edge of the detection layer  40 , one of the longitudinal edges, if it has a rectangular shape as is the case here. Note that the shape shown here is a sketch and it must be remembered that the detection layer  40  according to the invention can comprise recesses to surround the spokes  21 ,  22 ,  23  of the steering wheel. 
     In the present case, the connection portion of the presence sensor  41  is arranged between the other two presence sensors  42  and  43 . If a connection is envisaged with the onboard network at the bottom spoke  21  (located at 6 o&#39;clock), enabling the presence sensors  42  and  43  to be used in order to detect a presence on the outside left or right of the steering wheel, then the two ends of the detection layer  40  will be arranged at 12 o&#39;clock on the steering wheel. Positioning the connection zone  45  on the longitudinal side opposite the dot-dash line  46  results in this connection zone being positioned on the steering wheel, once the detection layer is sheathed on the steering wheel, above the spoke  21 . This simplifies the subsequent connection to the vehicle network because the spoke  21  need not be passed over by a cable bundle in order to connect the detection layer to the hub. Similarly, all of the connections are therefore made at one and the same spoke, which produces a simple cable bundle. 
     Alternatively, as shown in  FIG.  5   , the connection portions can be provided at the ends of a connection layer  40 ′, where the presence sensor  41 ′ is arranged between a connection portion of the presence sensor  42 ′ and a connection portion of the presence sensor  43 ′. Clearly, there is also a connection portion of the presence sensor  41 ′ and a connection portion of the grounding film or fabrics  44 ′, also at the ends, and always on the same longitudinal side of the connection layer  40 ′. Positioning the connection zone  45 ′ on the longitudinal side closest to the dot-dash line  46  results in this connection zone on the steering wheel being positioned, once the detection layer is sheathed on the steering wheel, beneath the spoke  21 . This requires the spoke  21  to be passed through or surrounded by a cable bundle in order to connect the detection layer to the hub. Here too all of the connections are therefore made at one and the same spoke, which produces a very simple cable bundle. 
     It will be understood that the various modifications and/or improvements obvious to a person skilled in the art can be made to the different embodiments of the invention described in the present description without departing from the scope of the invention defined by the accompanying claims.