Patent Publication Number: US-2023152174-A1

Title: Pressure sensor layout structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Japanese Patent Application No. 2021-187494 filed on Nov. 18, 2021, the disclosures of all of which are hereby incorporated by reference in their entireties. 
     TECHNICAL FIELD 
     The present invention relates to a pressure sensor layout structure of a vehicle. 
     BACKGROUND OF THE INVENTION 
     A structure has been known, as a pressure sensor layout structure of a vehicle, that includes a bumper reinforcement (bumper beam) extending in a vehicle width direction, an absorber made of foam resin and attached to a front of the bumper reinforcement via a bracket, a pressure tube extending in the vehicle width direction along a rear surface of the absorber, and pressure sensors installed at both ends of the pressure tube (see Japanese Patent No. 6070647 (hereinbelow, referred to as Patent Document 1), for example). In this pressure sensor layout structure, the pressure sensors detect pressure changes in the pressure tube at a time of collision of a vehicle and output detection signals to an electronic control unit. The electronic control unit calculates a collision load, effective mass of a collided object, and the like, based on the detection signals. The electronic control unit determines, based on calculation results, whether a command to deploy an airbag should be outputted or not, for example. 
     SUMMARY 
     Problems to be Solved 
     However, a conventional pressure sensor layout structure (see, Patent Document 1, for example) has a risk of the absorber being cut off at an end in the vehicle width direction thereof when the vehicle has had an offset collision. If the absorber is cut off at an end thereof, the pressure sensors cannot accurately detect pressure changes in the pressure tube at a time of a collision. 
     The present invention is therefore intended to provide a pressure sensor layout structure that allows a pressure sensor to accurately and stably detect a pressure change in a pressure tube even at an offset collision of a vehicle, to further enhance traffic safety. 
     Solution to Problem 
     A pressure sensor layout structure to solve the above-identified problem includes: a bumper beam; an absorber disposed at a front of the bumper beam; a pressure tube arranged between the bumper beam and the absorber; a pressure sensor attached to an end of the pressure tube; and a sensor cover fixed to a rear surface of the absorber, wherein the sensor cover is fixed to an end portion in a vehicle width direction of the absorber, at two or more positions which are located variously in the vehicle width direction. 
     Advantageous Effects of the Invention 
     The present invention provides a pressure sensor layout structure that allows the pressure sensor to accurately and stably detect a pressure change in the pressure tube even at an offset collision of the vehicle, to further enhance traffic safety. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an overall perspective view of a pressure sensor layout structure according to an embodiment of the present invention; 
         FIG.  2    is a cross-sectional view of the pressure sensor layout structure, taken along a line II-II in  FIG.  1   ; 
         FIG.  3    is an exploded perspective view of a left end in a vehicle width direction of the pressure sensor layout structure; 
         FIG.  4    is an exploded perspective view of an absorber-sensor-unit assembly of the pressure sensor layout structure; 
         FIG.  5    is a rear view of the absorber-sensor-unit assembly; and 
         FIG.  6    is a diagram to illustrate another fixing aspect for a pressure sensor. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a description is given in detail of an embodiment of a pressure sensor layout structure according to the present invention, with reference to the drawings as required. Note that a front-rear direction, an up-down direction, and a right-left direction in the following description are based on the arrowed directions in the drawings aligned with a front-rear direction, an up-down direction, and a right-left direction of a vehicle. 
       FIG.  1    is an overall perspective view of a pressure sensor layout structure according to the embodiment.  FIG.  2    is a cross-sectional view of the pressure sensor layout structure, taken along a line II-II in  FIG.  1   . Note that a pressure tube  5  and pressure sensors  6  are indicated by hidden lines (dotted lines) in  FIG.  1   . 
     As shown in  FIG.  1   , a pressure sensor layout structure  1  is assembled in a front bumper  10  of a vehicle. In particular, the pressure sensor layout structure  1  includes a bumper beam  2 , an absorber  3 , the pressure tube  5 , the pressure sensors  6 , and a sensor cover  8  (see  FIG.  3   ) to be described below. 
     &lt;&lt;Bumper Beam&gt;&gt; 
     The bumper beam  2  is a frame member of the front bumper  10  arranged at a front of the vehicle so as to extend in a vehicle width direction. The bumper beam  2  is in a substantially bow shape, convex forward in a planar view. In particular, the bumper beam  2  extends substantially linearly at the center in the vehicle width direction, and is curved so as to be gradually displaced rearward from the center toward an outer side in the vehicle width direction. 
     As shown in  FIG.  2   , the bumper beam  2  has a closed cross-sectional structure with a front member  11 , in a plate shape in a cross-sectional view, joined with a rear member  12 , in a hat shape in a cross-sectional view. The front member  11  has a flat vertical wall  26  corresponding to a bottom of the plate shape, an upper wall  27  formed to correspond to an upper edge of the plate shape and extending upward from an upper end of the vertical wall  26 , and a lower wall  28  formed to correspond to a lower edge of the plate shape and extending downward from a lower end of the vertical wall  26 , with the upper and lower walls  27 ,  28  each shifted forward with respect to the vertical wall  26  to form a step with the vertical wall  26 . That is, the front member  11  forms a recess  29  which has the vertical wall  26 , formed flat in an up-down direction, as a bottom and is shallow in a front-rear direction. 
     As shown in  FIG.  2   , the rear member  12  has a beam body  23  formed to correspond to a protruding portion of the hat shape, being open forward and closed at a rear end thereof, an upper flange  24  formed to correspond to a brim portion of the hat shape and extending upward from an upper open end of the beam body  23 , and a lower flange  25  formed to correspond to a brim portion of the hat shape and extending downward from a lower open end of the beam body  23 . The beam body  23  of the rear member  12  is formed, at a rear thereof, with beads  23   a  extending in the vehicle width direction (perpendicular to a plane of paper in  FIG.  2   ) and being convex rearward. The beads  23   a  are formed to be a pair of upper and lower beads at the rear end of the beam body  23 . 
     As shown in  FIG.  2   , the upper and lower flanges  24 ,  25  of the rear member  12  are formed to correspond to, and joined as described above with, the upper and lower walls  27 ,  28  of the front member  11 , respectively. In addition, the upper and lower flanges  24 ,  25  respectively have turned portions  24   a,    25   a  bent and extending rearward on the way of extending upward and downward, respectively, from the beam body  23 . A hooking portion  14  of the absorber  3  (see  FIG.  3   ) is engaged with an upper end and a lower end of the bumper beam  12 , where the turned portions  24   a,    25   a  are formed, to attach an absorber-sensor-unit assembly  30  (see  FIG.  4   ) to the bumper beam  2 , as described below. 
     Note that a reference sign  9  indicates an extension in  FIGS.  1  and  2   . The extension  9  is formed of a substantially square cylinder extending rearward from a rear surface at either end of the bumper beam  2 , as shown in  FIG.  1   . The extension  9  is connected to front ends of a front side frame and a side member, which are not shown, via a connection plate  9   a.  This allows the extension  9  to transmit a collision load inputted to the bumper beam  2  to the front side frame, as a vehicle body frame, and the like. 
     &lt;&lt;Absorber&gt;&gt; 
     As shown in  FIG.  1   , the absorber  3  includes an absorber body  13  formed in front of the bumper beam  2  so as to run along the bumper beam  2 , the hooking portion  14  located off the center toward an end in the vehicle width direction of the absorber body  13  and formed to be one with the absorber body  13 , and a sensor mount  15  formed to be one with the absorber body  13  so as to extend downward from an end in the vehicle width direction of the absorber body  13 . 
     As shown in  FIG.  1   , the absorber body  13  is in a substantially bow shape, convex forward in a planar view. That is, the absorber body  13  extends substantially linearly at the center in the vehicle width direction and is gradually displaced rearward from the center toward an outer side in the vehicle width direction so as to correspond to the bumper beam  2 . 
     As shown in  FIG.  2   , the absorber body  2  is an elongated member, in a cross-sectional view intersecting in the vehicle width direction (perpendicular to a plane of paper in  FIG.  2   ), with a front portion  33  having a vertical width substantially equal to that of the extension  9 , to be described below, formed to be one with a rear portion  32  having a vertical width substantially equal to that of the vertical wall  26  of the front member  11  of the bumper beam  2 . 
     The absorber body  13  is formed, on a rear end surface of the rear portion  32 , with a mount portion  31  for the pressure tube  5  (hereinafter, sometimes referred to as the tube mount portion  31 ). This tube mount portion  31  is formed so as to be raised rearward from a general surface  32   a,  which occupies majority of the rear end surface of the absorber body  13 . The tube mount portion  31  is formed with a tube insertion groove  31   a  extending in the vehicle width direction. The tube mount portion  31  in the present embodiment is formed at an upper portion of the rear end surface of the rear portion  32  of the absorber body  13 . 
     As shown in  FIG.  2   , the hooking portions  14  are provided in a pair at a top and a bottom of the absorber body  13  so as to respectively correspond to the turned portions  24   a,    25   a  of the upper and lower flanges  24 ,  25  of the bumper beam  2 . As shown in  FIG.  1   , the hooking portion  14  has a loop-shaped support portion  14   a  extending rearward from the absorber body  13  and a protrusion  14   b  protruding from the support portion  14   a  toward the bumper beam  2 . The hooking portions  14  have the protrusions  14   b  hooked onto the turned portions  24   a,    25   a,  as shown in  FIG.  2   , to cause the absorber body  13  to be supported by the bumper beam  2 . The pair of upper and lower hooking portions  14  are provided at each of two positions, one on the right and the other on the left, corresponding to the extensions  9 , as shown in  FIG.  1   . 
     The absorber body  13 , which is supported by the bumper beam  2  at the hooking portions  14  as described above, has the rear end of the rear portion  32  thereof fitted into the recess  29  of the bumper beam  2 , as shown in  FIG.  2   . This causes the tube mount portion  31  of the pressure tube  5  to contact the vertical wall  26  of the bumper beam  2 . Then, the general surface  32   a  of the rear end surface of the absorber body  13  is separated from the vertical wall  26  at a predetermined distance. In addition, stepped surfaces  34  formed between the front portion  33  and the rear portion  32  of the absorber body  13  respectively face the upper wall  27  and lower wall  28  of the front member  11  of the bumper beam  2  at predetermined distances. 
     As shown in  FIG.  1   , the sensor mount  15  is formed of a block body connected to a bottom surface, at an end in the vehicle width direction, of the absorber body  13 . The sensor mount  15  is described in detail, together with the absorber-sensor-unit assembly  30  (see  FIG.  4   ) to be described below. Note that the absorber  3  of the present embodiment is assumed to be one formed of resin foam such as urethane foam resin. 
     &lt;&lt;Pressure Tube and Pressure Sensor&gt;&gt; 
     Next, a description is given of the pressure tube (see  FIG.  1   ) and the pressure sensor  6  (see  FIG.  1   ).  FIG.  3    is an exploded perspective view of a left end in a vehicle width direction of the pressure sensor layout structure  1  in  FIG.  1   . The pressure tube  5  is arranged so as to extend in the vehicle width direction (right-left direction in  FIG.  3   ) between the bumper beam  2  and the absorber  3 , as shown in  FIG.  3   . In particular, the pressure tube  5  is fitted in, and supported by, the tube insertion groove  31   a  formed in the tube mount portion  31 , as shown in  FIG.  2   . 
     The pressure tube  5  of the present embodiment is assumed to be one formed of elastic resin material such as synthetic rubber. The pressure tube  5  has a pressure transmitting medium, such as air, sealed in a hollow thereof. When a collision load has been inputted to the absorber body  13  in  FIG.  2   , the pressure tube  5  has a cross-sectional shape of the hollow changed by the vertical wall  2  of the bumper beam  26 . This causes the pressure tube  5  to have the pressure in the hollow increased in proportion to the magnitude of the collision load. The pressure transmitting medium in the pressure tube  5  transmits the pressure change in the hollow of the pressure tube  5  to the pressure sensor  6  in  FIG.  3   , which is mounted at the end of the pressure tube  5 . 
     The pressure sensor  6  (see  FIG.  3   ) of the present embodiment has a substantially rectangular shape. The pressure sensor  6  converts a pressure change generated in the hollow of the pressure tube  5  into an electrical signal (detection signal) and outputs the detection signal to an electronic control unit, not shown, via a harness  7  connected to the pressure sensor  6 . The electronic control unit calculates a collision load, effective mass of the collided object, and the like, based on the detection signal. Based on the results of the calculation, the electronic control unit determines whether or not to output a deployment command to an airbag for a pedestrian, for example, so as to be deployed on an engine hood. 
     A sensor unit  4  having the pressure sensor  6 , the pressure tube  5  and the harness  7 , and the sensor cover  8  are attached to the absorber  3 , as shown in  FIG.  3   , to compose the absorber-sensor-unit assembly  30  (see  FIG.  4   ), to be described next. Note that the reference sign  9  in  FIG.  3    indicates the extension to be joined to the rear surface of the bumper beam  2 . 
     &lt;&lt;Absorber-Sensor-Unit Assembly&gt;&gt; 
     Next, the absorber-sensor-unit assembly  30  is described (see  FIG.  4   ).  FIG.  4    is an exploded perspective view of the absorber-sensor-unit assembly  30 . When the absorber-sensor-unit assembly  30  is constructed, the sensor unit  4 , except the harness  7  and a connector  7   a,  is first attached to the absorber  3 , as shown in  FIG.  4   . 
     In particular, the pressure tube  5  is inserted into the tube insertion groove  31   a  of the absorber body  13 . Then, the pressure sensor  6  is inserted and fitted into a hole  42  formed in the sensor mount  15 , which is located lower than the absorber body  13 . Incidentally, a block body, in a substantially rectangular shape, of the sensor mount  15  is positioned so as to be offset rearward from a rear surface  35  of an end portion of the absorber body  13 . 
     This forms a stepped surface  41  between a rear surface  39  of the sensor mount  15  and the rear surface  35  of the absorber body  13 . In addition, a groove  36  is formed from the sensor mount  15  to the end portion of the absorber body  13 . The groove  36  is to have the pressure tube  5 , extending from the pressure sensor  6  arranged in the hole  42 , fitted therein. 
     The sensor cover  8  is composed of a bent plate body. The sensor cover  8  of the present embodiment extends from the rear surface  39  of the sensor mount  15  to the stepped surface  41  of the sensor mount  15 , the rear surface  35  of the end portion of the absorber body  13 , an inner side surface  38  of the end portion of the absorber body  13 , and a back surface  37  of the absorber body  13 . 
     That is, the sensor cover  8  is bent so as to follow the rear surface  39  of the sensor mount  15 , the stepped surface  41  of the sensor mount  15 , the rear surface  35  of the end portion of the absorber body  13 , the inner side surface  38  of the end portion of the absorber body  13 , and the back surface  37  of the absorber body  13 . In addition, the sensor cover  8  is formed with a hole  19  at a portion corresponding to the stepped surface  41  of the sensor mount  15 . Further, the sensor cover  8  is formed with a hole  18  for connecting the connector  7   a  of the harness  7  with the pressure sensor  6  arranged in the hole  42  of the sensor mount  15 . 
     The sensor cover  8  as described above is fixed by clips C to the absorber  3  at two or more positions which are located variously in the vehicle width direction of the absorber  3 . The sensor cover  8  is fixed to the absorber  3  only. Having the connector  7   a  of the harness  7  connected with the pressure sensor  6  via the hole  18  completes the absorber-sensor-unit assembly  30 . 
       FIG.  5    is a partial rear view of the absorber-sensor-unit assembly  30  on the left side. Note that  FIG.  5    shows arranged positions of the bumper beam  2  and the extension  9  by imaginary lines (dash-dot-dot-dash lines). 
     Having the hooking portions  14  of the absorber  3  of the absorber-sensor-unit assembly  30  hooked to the bumper beam  2  forms the pressure sensor layout structure  1  (see  FIG.  1   ) according to the present embodiment. In the pressure sensor layout structure  1  ( FIG.  1   ) with the absorber-sensor-unit assembly  30  as described above, the pressure sensor  6  is positioned lower than the bumper beam  2  and the extension  9 . 
     The sensor cover  8  extends more downward than the bumper beam  2  and the extension  9 . The pressure sensor  6  is positioned outside in the vehicle width direction of the bumper beam  2 , with the sensor cover  8  extending from the bumper beam  2  to the position of the pressure sensor  6 . An end in the vehicle width direction of the sensor cover  8  is positioned outer in the vehicle width direction than an end in the vehicle width direction of the pressure sensor  6 . 
     In addition, the sensor cover  8  is formed with the hole  19  so as to be adjacent to an upper portion of the pressure sensor  6 . Further, the sensor cover  8  is fixed by the clips C to the absorber  3  at positions outer in the vehicle width direction than a center position P in the vehicle width direction of the pressure sensor  6 . Moreover, the sensor cover  8  partially overlaps with the extension  9  via the bumper beam  2  and also partially overlaps with an outer side surface in the vehicle width direction of the extension  9 , as shown in  FIG.  3   . 
     &lt;&lt;Advantageous Effects&gt;&gt; 
     Next, a description is given of advantageous effects of the pressure sensor layout structure  1  according to the present embodiment. The pressure sensor layout structure  1  has the sensor cover  8  fixed, at two or more positions which are located variously in the vehicle width direction, to the absorber  3  at the end portion in the vehicle width direction of the absorber  3 . With the pressure sensor layout structure  1  as described above, the sensor cover  8  can avoid the end portion in the vehicle width direction of the absorber  3  from dropping off, even if the absorber  3  is broken at a time of an offset collision of the vehicle. The pressure sensor layout structure  1  allows the pressure sensor  6  to accurately and stably detect a pressure change in the pressure tube  5 , even at a time of an offset collision of the vehicle. 
     A conventional pressure sensor layout structure (see Patent Document  1 , for example) may have a risk of an end portion of an absorber being broken at a time of an offset collision of a vehicle, causing the pressure sensor to drop off. In contrast, the pressure sensor layout structure  1  of the present embodiment effectively prevents the pressure sensor  6  from dropping off by the sensor cover  8  provided at the end portion of the absorber  3 , even if the absorber  3  is broken at a position outer in the vehicle width direction than the hooking portion  14 . 
     In addition, the pressure sensor layout structure  1  has the sensor cover  8  fixed to the absorber  3  only. According to the pressure sensor layout structure  1  as described above, there is no need to provide mount holes in the bumper beam  2 , unlike one having the sensor cover  8  fixed to the bumper beam  2 , to facilitate mounting the sensor cover  8 . Additionally, according to the pressure sensor layout structure  1  as described above, the absorber-sensor-unit assembly  30 , having the absorber  3  and the sensor cover  8  fixed in advance, allows for improving efficiency of mounting the absorber  3 , sensor unit  4 , and sensor cover  8  to the bumper beam  2 . 
     Further, the pressure sensor layout structure  1  has the pressure sensor  6  positioned lower than the bumper beam  2  and the extension  9 . According to the pressure sensor layout structure  1  as described above, the pressure sensor  6  is prevented from being held between the bumper beam  2  or the extension  9  and another member at a time of a collision of the vehicle, and then broken. 
     Still further, the pressure sensor layout structure  1  has the sensor cover  8  extending more downward than the bumper beam  2  and the extension  9 . According to the pressure sensor layout structure  1  as described above, the pressure tube  5  is prevented from being cut off by a lower edge of the bumper beam  2  or extension  9 , when a collision load is applied to the absorber  3 . 
     Still further, the pressure sensor layout structure  1  has the pressure sensor  6  positioned outside in the vehicle width direction of the bumper beam  2 , and the sensor cover  8  extending from the bumper beam  2  to the position of the pressure sensor  6 . According to the pressure sensor layout structure  1  as described above, the sensor cover  8  reliably prevents the end portion of the absorber  3  from dropping off, even if the absorber  3  has been broken at a time of an offset collision of the vehicle. 
     Still further, the pressure sensor layout structure  1  has the end in the vehicle width direction of the sensor cover  8  positioned outer in the vehicle width direction than the end in the vehicle width direction of the pressure sensor  6 . According to the pressure sensor layout structure  1  as described above, the sensor cover  8 , when a collision load is laterally inputted to the end portion of the absorber  3 , protects the pressure sensor  6  from being directly applied with the load. This reliably prevents the pressure sensor  6  from being broken. 
     Still further, the pressure sensor layout structure  1  has the sensor cover  8  formed with the hole  19  so as to be adjacent to the upper portion of the pressure sensor  6 . According to the pressure sensor layout structure  1  as described above, a stress of the sensor cover  8  is decreased around the hole  9 , when a collision load is laterally inputted to the end portion of the absorber  3 . The sensor cover  8  is thus prevented from being broken due to the load being concentrated at the sensor cover  8  locally. 
     Still further, the pressure sensor layout structure  1  has the sensor cover  8  fixed to the absorber  3  at positions outer in the vehicle width direction than the center position P in the vehicle width direction of the pressure sensor  6 . According to the pressure sensor layout structure  1  as described above, the pressure sensor  6  is more reliably prevented from dropping off, even if the absorber  3  is broken at a time of an offset collision of the vehicle. 
     Hereinabove, the present embodiment has been described, but the present invention is not limited thereto and can be implemented in various forms. In the present embodiment, the pressure sensor  6  is assumed to be fixed in the hole  42  of the sensor mount  15  formed in the absorber  3 , but a structure of fixing the pressure sensor  6  is not limited thereto.  FIG.  6    is a diagram to illustrate another fixing structure for the pressure sensor  6 , to indicate a structure of fixing the absorber-sensor-unit assembly  30  (see  FIG.  4   ) on the left side. 
     As shown in  FIG.  6   , a fixing part  21  for the pressure sensor  6 , formed in the sensor cover  8 , is in a concave shape, which is open rearward. In this fixing structure, the pressure sensor  6  has a sensor body  16  and a flange  17  provided at one end of the sensor body  16 . The fixing part  21  is formed with a pair of claws  22  to engage the flange  17  of the pressure sensor  6  fitted into the absorber  3 . Note that a reference sign  15  in  FIG.  6    indicates a sensor mount of the absorber  3 , and reference signs C indicates the clips to fix the sensor cover  8  to the absorber  3 . 
     According to the pressure sensor layout structure  1  as described above, the fixing part  21  for the pressure sensor  6 , formed in the sensor cover  6 , is in a concave shape and this facilitates the sensor cover  8  being bent, when a collision load is laterally inputted to the end portion of the absorber  3 , to decrease a stress. 
     According to the pressure sensor layout structure  1  as described above, the fixing part  21  has the claws  22  to engage the pressure sensor  6  fitted therein, to facilitate attaching the pressure sensor  6  to the fixing part  21 . 
     LIST OF REFERENCE SIGNS 
       1 : pressure sensor layout structure,  2 : bumper beam,  3 : absorber,  5 : pressure tube,  6 : pressure sensor,  8 : sensor cover,  9 : extension,  19 : hole formed in sensor cover,  21 : fixing part for pressure sensor, and  22 : claw for engaging pressure sensor.