Abstract:
A distance measuring sensor mounting structure includes a bulkhead upper frame, a front bumper beam situated below the bulkhead upper frame and diagonally to the front thereof and at least two sensor brackets each having a distance measuring sensor fixedly supported thereon. At least two sensor brackets are installed at predetermined positions between the bulkhead upper frame and the front bumper beam to connect the bulkhead upper frame to the front bumper beam.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a mounting structure for distance measuring sensors provided at the front of an automotive vehicle.  
           [0003]    2. Description of the Related Art  
           [0004]    In measuring a distance between the subject vehicle and a vehicle running or obstacle existing ahead of the subject vehicle by detecting the vehicle or obstacle, since it is not a close distance that is to be measured, a method is adopted which utilizes a triangulation in order to measure the distance accurately.  
           [0005]    Consequently, distance measuring sensors need to be disposed on at least two positions, a distance between which is known for a required measurement. And, in view of the distance measuring performance, the longer the distance between the two positions becomes, the more accurate a resultant measurement becomes. An example of such a distance measuring sensor placement is disclosed in JP-A-7-125567.  
           [0006]    In the example, a CCD camera is used as a distance measuring sensor, and two CCD cameras each installing into its body, electronic components such as an image circuit board and a diaphragm circuit board are provided at positions apart from each other by a predetermined distance.  
           [0007]    Unless the relative position between the two CCD cameras is maintained, no high-accuracy distance measurement can be expected. However, there is disclosed in the example no description of a distance measuring sensor mounting structure which can secure the accuracy of the relative position of the two CCD cameras.  
         SUMMARY OF THE INVENTION  
         [0008]    The invention was made in view of the situation, and an object thereof is to provide a distance measuring sensor mounting structure which can not only maintain the high accuracy of a relative position between two distance measuring sensors while the sensors keep a required relative distance between them but also increase the rigidity of the body of a vehicle.  
           [0009]    With a view to attaining the object, according to a first aspect of the invention, there is provided a distance measuring sensor mounting structure wherein at least two sensor brackets each having a distance measuring sensor fixedly supported thereon are provided at predetermined positions on an automotive body frame structure in such a manner as to extend between a bulkhead upper frame and a front bumper beam situated below the bulkhead upper frame diagonally to the front to connect the bulkhead upper frame to the front bumper beam.  
           [0010]    The bulkhead upper frame and the front bumper beam are respectively directed transversely and joined to the body of a vehicle to form a strong structure which constitutes the front of the body.  
           [0011]    Since at least two sensor brackets are provided to extend between the bulkhead upper frame and the front bumper beam which are disposed in parallel to each other, the rigidity of the overall structure can be increased, whereby the improvement in rigidity of the body of the vehicle can be attained.  
           [0012]    In addition, since the distance measuring sensor is fixedly supported on each sensor bracket which constitutes the highly rigid structure, the high accuracy of the relative position of the distance measuring sensors can be secured, enabling a highly accurate distance measurement.  
           [0013]    Furthermore, since the distance measuring sensors are fixed to the sensor brackets which are provided to extend between the bulkhead upper frame and the front bumper beam, the distance measuring sensors can be disposed to face the front grille without disposing therebetween any obstacle such as glass which would deteriorate the performance of the sensors.  
           [0014]    According to a second aspect of the invention, there is provided a distance measuring sensor mounting structure as set forth in the first aspect of the invention, wherein the sensor bracket comprises a bottom plate and a back plate which are disposed to form an L-shape as viewed from the side, wherein a rib is formed on the sensor bracket in such a manner as to connect the edge of the bottom bracket to the edge of the back plate, and wherein the bottom plate is fixedly attached to the front bumper beam whereas the back plate is fixedly attached to the bulkhead upper frame.  
           [0015]    Since in the sensor bracket the ribs connect together the edges of the bottom and back plates which are formed into the L-shape, the rigidity of the sensor bracket itself is improved, whereby the mounting strength of the distance measuring sensor can be maintained much higher. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a perspective view showing a front vehicle body frame structure of an automotive vehicle according to an embodiment of the invention;  
         [0017]    [0017]FIG. 2 is a front view of the structure;  
         [0018]    [0018]FIG. 3 is a side of the structure;  
         [0019]    [0019]FIG. 4 is a plan view of the structure;  
         [0020]    [0020]FIG. 5 is a perspective view showing an infrared camera and a sensor bracket;  
         [0021]    [0021]FIG. 6 is a front view of the sensor bracket;  
         [0022]    [0022]FIG. 7 is a side view showing a state in which the infrared camera is mounted on the sensor bracket; and  
         [0023]    [0023]FIG. 8 is an explanatory view explaining a distance measuring method.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    Referring to FIGS.  1  to  6 , an embodiment according to the invention will be described below.  
         [0025]    A distance measuring sensor according to the embodiment is constituted by a infrared camera, and two infrared cameras  1 L,  1 R are disposed at transversely symmetrical positions at the front of the body of a vehicle.  
         [0026]    A front bulkhead  11  constituting a front part of the vehicle body includes a transversely and horizontally directed bulkhead upper frame  12 , a front lower cross member  12  extending in parallel to the bulkhead upper frame therebelow and a center stay  14  connecting between central portions of the bulkhead upper frame  12  and the front lower cross member  13  which are disposed vertically.  
         [0027]    The bulkhead upper frame  12  constituting an upper part of the front bulkhead  11  connects to left and right wheel houses which are part of the main body of the vehicle. Left and right side portions of the front lower cross member  13  constituting a lower part of the front bulkhead  11  are curved obliquely upwardly so as to connect at left and right upper ends thereof to left and right side frames  20 L,  20 R, respectively, which are part of the main body of the vehicle.  
         [0028]    Consequently, the bulkhead upper frame  12  and the front lower cross member  13  which are disposed vertically are both connected to the main body of the vehicle, thereby constituting a highly rigid structure.  
         [0029]    On the other hand, the left and right side frames  20 L,  20 R which are directed longitudinally protrude more frontward than the front bulkhead  11 , and a front bumper beam  21  directed transversely is provided in such a manner as to extend between left and right distal ends of the left and right side frames  20 L,  20 R.  
         [0030]    Distal ends of the side frames  20 L,  20 R are fitted in U-shaped portions opened in the back side the front bumper beam  21  at left and right end portions thereof and are then fixedly attached thereto with bolts  22 ,  23 .  
         [0031]    The front bumper beam  21  is located ahead of the front bulk head  11  at a height between the bulkhead upper frame  12  and the front lower cross member  13 .  
         [0032]    Consequently, the front bumper beam  21  is disposed below and in parallel with respect to the bulkhead upper frame  12  and diagonally to the front of thereof.  
         [0033]    Two sensor brackets  31 L,  31 R, which are transversely symmetrical with each other, are provided in such a manner as to extend between the bulkhead upper frame  12  and the front bumper beam  21  which are in the aforesaid positional relationship.  
         [0034]    As shown in FIGS. 5 and 6, the left-hand side sensor bracket  31 L is formed into an L-shape as viewed from the side with a bottom plate  32  and a back plate  33 , and ribs  34 ,  34  connect the end of an end of the bottom plate  32  and the edge of the back plate  33  to provide a highly rigid structure.  
         [0035]    Three attachment holes  32   a  are provided in the bottom plates  32  of the sensor brackets  31 L,  31 R along front end portions of the bottom plates  32 , and two attachment holes  33   a  are provided in the back plates  33  of the same sensor brackets along the upper end portions thereof. In addition, two rectangularholes 33   b ,  33   b  are formed in the back plates  33  of the respective sensor brackets  31 L,  31 R at corners which confront each other diagonally for fixing infrared cameras  1 L,  1 R, and small holes  33   c  are provided on left and right sides of each rectangular hole  33   b . Moreover, a circular hole  33   d  is formed in the other lower corner portion of the back plate  33  and a small hole  33   e  is formed above the circular hole  33   d.    
         [0036]    Note that while the left and right sensor brackets  31 L,  31 R are formed symmetrically with each other, the sensor brackets may not have to be formed symmetrically but may be formed in the same shape.  
         [0037]    On the other hand, the infrared cameras  1 L,  1 R are each formed into a shape in which a cylindrical portion  3  constituting a lens system protrudes from a rectangular main body portion  2 , brackets  4  extend in three directions from the main body portion  2 , and an attachment hole  4   a  is provided in each bracket  4  at a distal end thereof.  
         [0038]    The left and right infrared cameras  1 L,  1 R are transversely symmetrical with each other with respect to directions in which the brackets extend.  
         [0039]    As shown in FIG. 5, a backside of the infrared camera  1 L is confronted with the back plate  33  of the sensor bracket  31 L and is then fixed thereto via one reference support member  35  and two adjustable support members  36 ,  37 .  
         [0040]    The reference support member  35  is something like a rectangular prism with a predetermined longitudinal length. A bolt hole  35   a  penetrates longitudinally through the rectangular prism, and an engagement pin  35   b  protrudes upwardly along a backside of the reference support member  35 . Further, an engagement pawl is formed on an upper end of the engagement pin  35   b.    
         [0041]    The adjustable support members  36 ,  37  respectively include attachment tab portions  36   a ,  37   a  provided on left- and right-hand sides of rectangular prism cases of the adjustable support members  36 ,  37  in such a manner as to protrude therefrom, and threaded rods  36   b ,  37   b  protrude from front sides of the respective rectangular prism cases while adjustment pins  36   c ,  37   c  protrude upwardly from upper sides of the respective cases.  
         [0042]    Incorporated in the rectangular prism cases of the respective adjustable support members  36 ,  37  are mechanisms in which when upper ends of the adjustment pins  36   c ,  37   c  are turned, the threaded rods  36   b ,  37   b  move longitudinally.  
         [0043]    The two adjustable support members  36 ,  37  are fitted in advance into the rectangular holes  33   b ,  33   b  in the sensor bracket  31 L from the front so that the left and right attachment tab portion  36   a ,  37   a  come into alignment with the small holes  33   c , and bolts  38  are allowed to penetrate through the holes and be threadedly fitted to nuts  39 .  
         [0044]    Then, the backside of the infrared camera  1 L is caused to face the back plate  33  of the sensor bracket  31 L, the reference support member  35  is brought into alignment with the circular hole  33   d , and the engagement pawl of the engagement pin  35   b  is brought into engagement with the small hole  33   e  to provide a detent. Then, the left lower bracket  4  of the infrared camera  1 L is brought into abutment with a front side of the reference support member  35 , the threaded rod  36   b  of the adjustable support member  36  is allowed to penetrate through the attachment hole  4   a  in the left upper bracket  4 , and the threaded rod  37   b  of the adjustable support member  37  is allowed to penetrate through the attachment hole  4   a  in the right lower bracket  4 .  
         [0045]    In this state, a bolt  40  is allowed to penetrate through the attachment hole  4   a  in the left lower bracket  4  of the infrared camera  1 L, the holt hole  35   a  in the reference support member  35  and the circular hole  33   d  in the back plate  33 , to be threadedly fastened to a nut  41 , whereby the left lower bracket  4  is fixed (refer to FIG. 7).  
         [0046]    Thus, the infrared camera  1 L is supported on the back plate  33  of the sensor bracket  31 L via the single reference support member  35  and the two adjustable support members  36 ,  37 , the left lower bracket  4  is fixedly supported by the reference support member  35 , and the left upper bracket  4  and the right lower bracket  4  are adjustably supported by the adjustable support members  36 ,  37 .  
         [0047]    Namely, in the adjustable support members  36 ,  37 , since the threaded rods  36   b ,  37   b  can be adjusted longitudinally by turning the adjustment pins  36   c ,  37   c , the left upper bracket  4  and the right lower bracket  4  can be adjusted relative to the fixed left lower bracket  4 .  
         [0048]    As shown in FIG. 7, the threaded rod  36   b  moves longitudinally together with the left upper bracket  4  by turning the adjustment pin  36   c  of the left upper adjustable support member  36 , whereby through the longitudinal movement of the left upper bracket  4  relative to the fixed left lower bracket  4  the direction of a lens of the infrared camera  1 L can be tilted vertically as illustrated by two-dot chain lines for fine adjustment in vertical direction.  
         [0049]    In addition, when turning the adjustment pin  37   c  of the right lower adjustable support member  37 , the right lower bracket  4  moves longitudinally relative to the fixed left lower bracket  4 , whereby the direction of the lens of the infrared camera  1 L can be tilted horizontally for fine adjustment in horizontal direction.  
         [0050]    While the left-hand side infrared camera  1 L has been described heretofore, the right-hand side infrared camera  1 R is mounted on the sensor bracket  31 R transversely symmetrically with the left-hand side one, and hence the right-hand side camera can also be tilted vertically and horizontally for adjustment in vertical and horizontal directions.  
         [0051]    The bottom plates  32  of the sensor brackets  31 L,  31 R are placed on predetermined positions on an upper side of the front bumper beam  21  while the back plates  33  thereof are brought into abutment with the bulkhead upper frame  12  at predetermined positions on a front side thereof. Then, the bottom plates  32  are threadedly attached to the front bumper beam  21  with bolts  45  which have penetrated through the attachment holes  32   a  in the bottom plates  32  while the back plates  33  are threadedly attached to the bulkhead upper frame  12  with bolts  46  which have penetrated through attachment holes  33   a  in the back plates  33 , whereby the sensor brackets  31 L,  31 R extend between the bulkhead upper frame  12  and the front bumper beam  21  so as to connect them together.  
         [0052]    The left and right sensor brackets  31 L,  31 R are fixed at predetermined left and right positions between the bulkhead upper frame  12  and the front bumper beam  21 , and the infrared cameras  1 L,  1 R are fixedly supported on the sensor brackets  31 L,  31 R, respectively. Thus, a relative distance D between the two infrared cameras  1 L,  1 R is maintained to a predetermined length.  
         [0053]    As has been described heretofore, the bulkhead upper frame  12  and the front bumper beam  21  are directed transversely of the vehicle main body and connect to the wheel houses and the side frames  20 L,  20 R, thereby forming a strong structure at the front part of the vehicle body. Since the sensor brackets  31 L,  31 R are provided to extend between the bulkhead upper frame  12  and the front bumper beam  21  which are so constructed, an overall structure can be provided which is higher in rigidity.  
         [0054]    Since the infrared cameras  1 L,  1 R are fixed to the sensor brackets  31 L,  31 R, respectively, which constitute the highly rigid structure, the infrared cameras  1 L,  1 R are fixed securely whereby the relative distance D can be maintained to the predetermined length in an ensured manner.  
         [0055]    In addition, the highly rigid structure can be provided to thereby improve the rigidity of the overall vehicle body.  
         [0056]    The left and right infrared cameras  1 L,  1 R provided on the front side of the upper portion of the front bulkhead frame  11  as has been described above are concealed below a front portion of a bonnet covering over an engine compartment, and confront the front grill  51  opened forwardly (external panels of the vehicle body are indicated by two-dot chain lines in FIGS.  1  to  4 ).  
         [0057]    Consequently, the infrared cameras  1 L,  1 R can receive infrared rays directly without transmitting an obstacle such as glass, and hence, there being thereby no risk that the performance of the cameras is deteriorated.  
         [0058]    As shown in FIG. 8, the infrared cameras  1 L,  1 R which are spaced away from each other by the predetermined distance D receive infrared rays from an object thereof such as a pedestrian waling ahead thereof through the lens  1 , and an image of the pedestrian is formed on the surfaces of infrared detection elements i disposed second-dimensionally at a focal length f of the lens  1 .  
         [0059]    Assuming that a formed image of the object deviates a distance S 1  from the center in the right-hand side infrared camera  1 R whereas a formed image of the object deviates a distance S 2  from the center in the left-hand side infrared camera  1 L, a distance L to the object can be obtained as follows; L=Df/(S2−S1).  
         [0060]    Namely, assuming that a transverse deviation of the object from the right-hand side infrared camera is W, the following two expressions can be established;  
         ( L+f )/( W+S 1)=/S1  
         ( L+f )/( W+D+S 2)=f/S2  
         [0061]    and, the distance L can be obtained by deleting W from the two expressions.  
         [0062]    While the distance is measured using the two infrared cameras  1 L,  1 R in the above embodiment, three or more cameras may be arranged in parallel to each other at predetermined intervals, so that measurement results obtained from a pair of cameras can be combined to obtain more reliable measurement results.  
         [0063]    The measuring of distance can be implemented extremely quickly, and the measurement can be effected even in the dark because infrared rays are used.  
         [0064]    As distance measuring sensors, in addition to the infrared cameras, CCD cameras and sensors such as radio sensors and radars may be used.  
         [0065]    While only certain embodiments of the invention have been specifically described herein, it will apparent that numerous modifications may be made thereto without departing from the spirit and scope of the invention.