Patent Publication Number: US-2023138220-A1

Title: Front structure of vehicle

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a front structure of a vehicle, and specifically relates to the front structure of the vehicle which comprises a beam member positioned in front of a sub frame and having a closed-cross section extending in a vehicle width direction and a plate member extending forwardly from the beam member. 
     Conventionally, the following structure is known as the front structure of the vehicle. That is, the structure, in which a pair of right-and-left extension members are provided in front of a sub frame (suspension cross member), a metal-plate-made beam member is attached to respective front portions of the right-and-left extension members via respective lower-side crash cans, and a plate member (a so-called foot sweeping member) like a lower stiffener is provided in front of the beam member, is known. 
     In this conventional front structure of the vehicle, generation of an appropriate reaction force and performance of energy absorption can be compatibly attained through deformation of the plate member and deflection of the metal-plate-made beam member in a vehicle collision against a pedestrian and also unexpected damage for vehicle parts, such as a cooling member, can be suppressed even in a case of a light vehicle collision. 
     However, this conventional vehicle structure has a problem that a section of the structure which corresponds to the lower-side crash cans may cause damage to a counter vehicle if this structure is applied to a MPDB collision test which is supposed to be introduced in the near feature. The MPDB collision test is a collision test using a Mobile Progressive deformable Barrier (i.e., a front-movable type of deformable barrier) for evaluating injuriousness to the counter vehicle. 
     Herein, it may be considered that the high-rigidity beam member having the closed-cross section is used in place of the conventional metal-plate-made beam member and also a resin-made plate member, which is disclosed in Japanese Patent Laid-Open Publication No. 2008-265399, for example, is used as the above-described plate member. 
     In this case, when the vehicle has the light collision, the crushed plate member stays at a lower part of the beam member and the beam member rotates around a width-directional axis (an imaginary axis extending in the vehicle width direction), without being deformed, so that the lower-side crash cans come to be bent/deformed without being axially compressed. 
     Consequently, there may occur an unexpected contact with surrounding vehicle parts, such as the cooling member. Further, in terms of protection of the pedestrian, since the high-rigidity beam member is not deformed properly, the reaction force may become too high, so that the damage degree may be improperly increased. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a front structure of a vehicle which can compatibly attain the pedestrian-protection performance and the vehicle-parts damage suppression in the vehicle light collision even if the plate member is applied to the beam member having the closed-cross section. 
     The present invention is the front structure of the vehicle which comprises a beam member positioned in front of a sub frame and having a closed-cross section extending in a vehicle width direction, and a plate member extending forwardly from the beam member, wherein the plate member comprises a fixation portion fixed to the beam member, a body portion extending forwardly from the fixation portion, and a front end portion positioned at a front end of the body portion and configured to have higher rigidity against a load applied in a longitudinal direction than the body portion, the front end portion of the plate member comprises an upper section located at a higher level than the body portion and a lower section located at a lower level than the body portion, and the upper section is positioned on a vehicle forward side of the lower section. 
     According to the present invention, even if the vehicle collides against the pedestrian from any direction, the front end portion of the plate member transmits a collision load to the body portion so as to allow the body portion to be deformed with a constant load. Thereby, an appropriate reaction force can be generated. 
     Further, in a vehicle frontal collision, since a load input happens at the upper section of the front end portion of the plate member earlier than the lower section, there occurs a moment to cause an upper end of the front end portion to rotate such that its rear side is moved more downwardly, so that the body portion of the plate member is deflected downwardly. Thereby, the body portion can be suppressed from being crushed at a front face of the beam member. That is, even if the plate member is applied to the beam member having the closed-cross section, the pedestrian-protection performance and the vehicle-parts damage suppression in the vehicle light collision can be compatibly attained. 
     As an embodiment of the present invention, the front end portion of the plate member may comprise the lower section which protrudes downwardly from the front end of the body portion and the upper section which is positioned at a front end of the lower section. 
     According to this embodiment, a border portion between the body portion and the lower section becomes a bending causing point to cause rotation of the front end portion in the vehicle frontal collision by its bending. 
     As another embodiment of the present invention, a rib which connects a front end of the front end portion and the body portion may be provided. 
     According to this embodiment, the front end portion can be configured to have the high rigidity with a simple structure. 
     As another embodiment of the present invention, the beam member may comprise a central portion which is positioned at a central side, in the vehicle width direction, of the beam member and extends in the vehicle width direction and both-end portions which are positioned on both sides, in the vehicle width direction, of the central portion and configured to extend obliquely outwardly-and-rearwardly from both-side ends of the central portion in a plan view, and the rib which is provided at a position, in the vehicle width direction, of the front end portion which corresponds to the central portion of the beam member may be configured to extend obliquely outwardly-and-rearwardly in the plan view. 
     According to this embodiment, since the rib provided at the position, in the vehicle width direction, of the front end portion which corresponds to the central portion of the beam member extends obliquely outwardly-and-rearwardly in the plan view, the rib is crushed completely. If this rib is configured to extend straightly in the longitudinal direction, the rib resists the vehicle-frontal collision load to a considerably-large extent, so that this rib may not be crushed completely, that is, part of the rib may remain uncrushed. Meanwhile, since the rib of this embodiment is inclined relative to the vehicle longitudinal direction as described above, falling down of the rib is promoted, so that the rib&#39;s complete crushing can be promoted. 
     As another embodiment of the present invention, the front end portion of the plate member may be configured to have a forwardly-inclined shape. 
     According to this embodiment, the moment to cause the upper end of the front end portion to rotate such that its rear side is moved more downwardly becomes larger, so that the downward deflection of the body portion can be secured. Moreover, a stroke of the rearward rotation of the front end portion can be secured sufficiently, so that the front end portion can be suppressed from interfering with the body portion, thereby allowing the sufficient rotation of the front end portion. 
     As another embodiment of the present invention, the body portion of the plate member may be configured to have a liner shape, and a lower rib which connects the fixation portion and the front end portion may be provided at a lower face of the body portion. 
     According to this embodiment, the reaction force in the pedestrian&#39;s protection can be adjusted by the lower rib. Further, since the rigidity of the body portion is improved by the lower rib, the body portion can be securely deflected downwardly without buckling or bending in the vehicle frontal collision. 
     As another embodiment of the present invention, a lower end of the lower rib may be located at a higher level than a lower end of the lower section of the front end portion of the plate member. 
     According to this embodiment, the rotation of the front end portion in the vehicle frontal collision is not hindered by the lower rib. Further, the collision reaction force in the pedestrian protection can be adjusted by the lower rib. 
     As another embodiment of the present invention, an under-cover attachment portion may be provided at a base portion of the body portion of the plate member such that the under-cover attachment portion extends downwardly from the base portion of the body portion, and a notch may be formed at a base portion of the under-cover attachment portion. 
     According to this embodiment, since the notch becomes a fragile portion, the body portion can be bent downwardly with a supporting point of the base portion, i.e., a root portion, of the body portion because the notch becomes a bending causing point. Thereby, a position where a tip-side part of the body portion remains uncrushed can be moved downwardly. 
     Thus, according to the present invention, the pedestrian-protection performance and the vehicle-parts damage suppression in the vehicle light collision can be compatibly attained even if the plate member is applied to the beam member having the closed-cross section. 
     The present invention will become apparent from the following description which refers to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an upper-face perspective view showing a front structure of a vehicle. 
         FIG.  2    is a lower-face perspective view showing the front structure of the vehicle. 
         FIG.  3    is a perspective view showing a plate member, when viewed from a rearward-and-downward side of the vehicle. 
         FIG.  4    is a plan view showing a beam member, the plate member, and a lower-side crash can. 
         FIG.  5    is an enlarged plan view of a central portion, in a vehicle width direction, of  FIG.  4   . 
         FIG.  6 A  is a sectional view take along line A-A of  FIG.  4   ,  FIG.  6 B  is a sectional view take along line B-B of  FIG.  4   , and  FIG.  6 C  is a sectional view take along line C-C of  FIG.  4   . 
         FIG.  7    is a perspective view showing a notch and a protrusion face portion. 
         FIG.  8    is a perspective vertical-direction sectional view of a major part of  FIG.  7   . 
         FIG.  9    is a partial plan view showing a relation between a barrier and the protrusion face portion in a predetermined collision mode. 
         FIG.  10    is a schematic side view showing deformation at a first stage in a vehicle frontal collision. 
         FIG.  11    is a schematic side view showing deformation at a second stage in the vehicle frontal collision. 
         FIG.  12    is a schematic side view showing deformation at a third stage in the vehicle frontal collision. 
         FIG.  13    is a schematic side view showing deformation at a fourth stage in the vehicle frontal collision. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will be described specifically referring to the drawings. The drawings show a front structure of a vehicle, wherein  FIG.  1    is an upper-face perspective view showing the front structure of the vehicle,  FIG.  2    is a lower-face perspective view showing the front structure of the vehicle,  FIG.  3    is a perspective view showing a plate member, when viewed from a rearward-and-downward side of the vehicle, and  FIG.  4    is a plan view showing a beam member, the plate member, and a lower-side crash can. 
     Further,  FIG.  5    is an enlarged plan view of a central portion, in a vehicle width direction, of  FIG.  4   ,  FIG.  6 A  is a sectional view take along line A-A of  FIG.  4   ,  FIG.  6 B  is a sectional view take along line B-B of  FIG.  4   ,  FIG.  6 C  is a sectional view take along line C-C of  FIG.  4   ,  FIG.  7    is a perspective view showing a notch and a protrusion face portion, and  FIG.  8    is a perspective vertical-direction sectional view of a major part of  FIG.  7   . Moreover,  FIG.  9    is a partial plan view showing a relation between a barrier and the protrusion face portion in a predetermined collision mode. 
     As shown in  FIG.  1   , a dash lower panel (dash panel)  1  which partitions an engine room from a cabin in a vehicle longitudinal direction is provided, and a pair of front side frames  3  which extend forwardly from right-and-left both-side portions, in a vehicle width direction, of a tunnel portion  2  which is formed at the dash lower panel  1  are provided. 
     The above-described front side frame  3  is a vehicle-body rigidity member which has a front-side closed-cross section extending in the vehicle longitudinal direction which is formed by fixedly joining a front side frame inner and a front side frame outer. 
     An upper-side crash can  6  extending in the vehicle longitudinal direction is attached to a front end portion of the front side frame  3  via a plate-shaped set plate  4  and a plate-shaped attachment plate  5 . As shown in  FIGS.  1  and  2   , the upper-side crash can  6  is attached to the front end portion of each of the right-and-left front side frames  3 , and a bumper reinforcement  7  is attached to respective front end portions of a pair of right-and-left upper-side crash cans  6 . 
     As shown in  FIG.  1   , the bumper reinforcement  7  is formed by two members of a plate-shaped bumper plate  7   a  which is positioned at a front side and a bumper plate  7   b  which has a closed-cross section structure and is positioned at a rear side, and the bumper reinforcement  7  extends in the vehicle width direction in front of the upper-side crash cans  6 . 
     As shown in  FIG.  1   , an apron reinforcement  8  which extends in the vehicle longitudinal direction is provided above the front side frame  3  and on an outward side, in the vehicle width direction, of the front side frame  3 . This apron reinforcement  8  is a vehicle-body strength member which has an apron-reinforcement closed-cross section extending in the vehicle longitudinal direction, a rear portion of which is connected to a hinge pillar directly or indirectly. 
     As shown in  FIG.  1   , a shroud upper panel  9  is provided to interconnect respective front end portions of the pair of right-and-left apron reinforcements  8 ,  8  in the vehicle width direction. In the present embodiment, the shroud upper panel  9  is formed by three members of a shroud-upper central portion  9   a  which is positioned at a center, in the vehicle width direction, thereof and shroud-upper side portions  9   b,    9   c  which are positioned at right-and-left both sides, in the vehicle width direction, thereof. 
     Further, as shown in  FIGS.  1  and  2   , there is provided a connecting member  10  which connects in a vertical direction a front portion of the front side frame  3  which is located at a lower side, and the shroud upper panel  9  and the apron reinforcement  8  which are located at an upper side. 
     Moreover, as shown in  FIGS.  1  and  2   , there is provided a suspension housing  11  which connects in the vertical direction the apron reinforcement  8  which is located at the upper side and the front side frame  3  which is located at the lower side. This suspension housing  11  comprises a front-suspension tower portion  12 . 
     Meanwhile, as shown in  FIG.  1   , a dash-lower reinforcing member  13  is fixedly joined to a front portion of the dash lower panel  1 , and a dash-lower closed-cross section which extends in a longitudinal direction of the dash-lower reinforcing member  13  is formed between the dash-lower reinforcing member  13  and the dash lower panel  1 . 
     The dash-lower reinforcing member  13  is formed integrally at a front end portion of the tunnel portion  2  by an arch-shaped portion  13   a  which is formed in an arch shape along a shape of the tunnel portion  2  and a horizontal portion  13   b  which nearly horizontally extends outwardly, in the vehicle width direction, from a lower end portion of the arch-shaped portion  13   a.    
     Herein, as shown in  FIGS.  1  and  2   , a sub frame (suspension cross member)  14  is provided at a lower part of the engine room. The sub frame  14  is formed by a front cross member  15  as a sub-frame body, a rear cross member  16  (see  FIG.  1   ) which is positioned on a rearward side, in the vehicle longitudinal direction, of the front cross member  15 , and right-and-left side members  17 ,  17  which respectively connect the front cross member  15  and the rear cross member  16  in the vehicle longitudinal direction, which are connected together in a frame shape in the plan view. 
     As shown in  FIGS.  1  and  2   , a suspension-arm support bracket  18  to support a vehicle-body-side end portion of a front suspension, not illustrated, is attached to a front portion of the side member  17 . Further, as shown in the same figures, an extension member  19  which extends forwardly is provided at a front end portion of the side member  17 . 
     The extension member  19  is formed in a hollow shape by combining an upper-split member and a lower-split member, and configured such that a width, in the vehicle width direction, of a front portion of the extension member  19  is wider than that of a rear portion of the extension member  19 . 
     The extension member  19  is provided at the front end portion of each of the pair of right-and-left side members  17 ,  17 , a cross member  20  which extends in the vehicle width direction is provided between respective front portions of the pair of right-and-left extension members  19 ,  19 . 
     As shown in  FIG.  2   , a lower-side crash can  23  which extends in the vehicle longitudinal direction is attached to a front end portion of each of the extension members  19 ,  19  via a plate-shaped set plate  21  and a plate-shaped attachment plate  22 . A beam member  24  extending in the vehicle width direction (specifically, a perimeter beam) is attached to respective front end portions of a pair of right-and-left lower-side crash cans  23 . 
     As shown in  FIGS.  6 A,  6 B and  6 C , the beam member  24  is formed such that a front wall  24   a,  a rear wall  24   b,  an upper wall  24   c,  and a lower wall  24   d  are combined together in a rectangular frame shape, a partition wall  24   e  which is parallel to the upper-and-lower walls  24   c,    24   d  is formed between the front wall  24   a  and the rear wall  24   b,  whereby two closed-cross sections  25 ,  26  are formed. The beam member  24  can be made of an aluminum-made or aluminum-alloy-made extrusion molding member. 
     That is, as shown in  FIG.  2   , the beam member  24  is a member which is positioned in front of the sub frame  14  and has the closed-cross sections  25 ,  26  extending in the vehicle width direction. Further, the beam member  24  comprises, as shown in  FIG.  4   , a central portion  27  which is positioned at a central side, in the vehicle width direction, of the beam member  24  and extends in the vehicle width direction and both-end portions  28 ,  28  which are positioned on both sides, in the vehicle width direction, of the central portion  27  and configured to extend obliquely outwardly-and-rearwardly from both-side ends of the central portion  27  in the plan view. 
     As shown in  FIGS.  1 ,  2  and  6   , there is provided a lower stiffener  30  as a plate member which extends forwardly from the beam member  24 . This lower stiffener  30  is made of resin and configured such that its front end reaches a position close to a back face of a front bumper face (not illustrated), and this lower stiffener  30  is a so-called foot sweeping member which prevents a portion around an ankle of a pedestrian&#39;s foot from coming into a lower side of the vehicle when the vehicle contacts (collides against) a pedestrian. 
     As shown in  FIGS.  3 ,  4  and  6   , the lower stiffener  30  comprises a vertical face portion  31  which is provided along a front face portion of the beam member  24 , plural fixation portions  32  which fix the vertical face portion  31  to the beam member  24 , a body portion  33  which extends forwardly from the vertical face portion  31  including the fixation portions  32 , and a front end portion  34  which is positioned at a front end of the body portion  33  and configured to have high rigidity against a load applied in the longitudinal direction than the body portion  33 . 
     Further, as shown in the same figures, the lower stiffener  30  comprises protrusion face portions  35  which are forwardly spaced from the vertical face portion  31 . As shown in  FIGS.  3  and  6   , the vertical face portion  31  extends in the vertical direction in a side view, and as shown in  FIG.  4   , the vertical face portion  31  is formed in the plan view such as it extends along a front face of the central portion  27  of the beam member  24  and front faces of the both-end portions  28 ,  28  of the bean member  24 . 
     As shown in  FIG.  3   , the plural (six, in the present embodiment) fixation portions  32  to fix the vertical face portion  31  to the beam member  24  are provided such that they are positioned at intervals in the vehicle width direction. Herein, the number of the plural fixation portions  32  is not to be limited to six, and any number more than or less than six is applicable. The fixation portions  32  are fixed to the front face portion of the beam member  24  by using the plural fixation members  36  shown in  FIG.  1   . 
     As shown in  FIGS.  6 A,  6 B and  6 C , the body portion  33  extends forwardly from the vertical face portion  31  including the fixation portions  32  substantially perpendicularly to the vertical face portion  31 . Further, as shown in the same figures, the body portion  33  is configured to have a liner shape. As shown in  FIGS.  6 A,  6 B and  6 C , the front end portion  34  configured to have the higher rigidity against the longitudinal load than the body portion  33  comprises a rear-side inclined piece portion  37  which extends obliquely forwardly-and-downwardly from the front end of the body portion  33 , a front-side inclined piece portion  38  which extends obliquely forwardly-and-upwardly from a lower end of the rear-side inclined piece portion  37 , and a front piece portion  39  which extends substantially just upwardly from an upper end of the front-side inclined piece portion  38 . 
     That is, the front end portion  34  is formed by the above-described respective piece portions  37 ,  38 ,  39  as shown by an enclosing imaginary line in  FIG.  6 A . Moreover, the front end portion  34  comprises, as shown in  FIGS.  6 A,  6 B and  6 C , a front-end-portion upper section  34 U which is located above the body portion  33  and a front-end-portion lower section  34 L which is located below the body portion  33 , and the front-end-portion upper section  34 U is positioned on the forward side of the front-end-portion lower section  34 L. In the present embodiment, the front-end-portion upper section  34 U is formed by the front piece portion  39 , and the front-end-portion lower section  34 L is formed by both of the rear-side inclined piece portion  37  and the front-side inclined piece portion  38 . 
     Thereby, even if the vehicle collides against the pedestrian from any direction, the front end portion  34  transmits the load to the body portion  33  so as to allow the body portion  33  to be deformed with a constant load, so that an appropriate reaction force is generated. 
     Further, in the vehicle frontal collision, since a load input happens at the front-end-portion upper section  34 U earlier than the front-end-portion lower section  34 L, there occurs a moment to cause the upper end of the front end portion  34  to rotate such that its rear side is moved more downwardly, so that the body portion  33  is deflected downwardly. Thereby, the body portion  33  is suppressed from being crushed at the front face of the beam member  24 . That is, even if the lower stiffener  30  is applied to the beam member  24  having the closed-cross sections  25 ,  26 , the pedestrian-protection performance and the vehicle-parts damage suppression in the vehicle light collision are compatibly attained. 
     Moreover, as shown in  FIGS.  6 A,  6 B and  6 C , the front end portion  34  comprises the front-end-portion lower section  34 L which protrudes downwardly from the front end of the body portion  33  and the front-end-portion upper section  34 U which is positioned at a front end of the front-end-portion lower section  34 L, specifically at a front end of the front-side inclination piece portion  38 . Thereby, a border portion a between the body portion  33  and the front-end-portion lower section  34 L becomes a bending causing point where the front end portion  34  is rotated in the vehicle frontal collision. 
     Also, as shown in  FIGS.  6 A,  6 B and  6 C , the front end portion  34  is configured to have a forwardly-inclined shape such that its front side is located at a higher level than its rear side. Thereby, the moment to cause the upper end of the front end portion  34 , specifically an upper end of the front piece portion  39 , to rotate such that its rear side is moved more downwardly becomes larger, so that the downward deflection of the body portion  33  is secured. 
     Moreover, according to the above-described forwardly-inclined shape, a stroke of the rearward rotation of the front end portion  34  can be secured sufficiently, so that the front end portion is suppressed from interfering with the body portion  33 , thereby allowing the sufficient rotation of the front end portion  34 . 
     As shown in  FIGS.  3  and  6 A , a hook portion  40  to be inserted into a hole portion  24   f  which is formed at the front wall  24   a  of the beam member  24  is integrally formed at a central portion, in the vehicle width direction, of the vertical face portion  31  of the lower stiffener  30 . By inserting the hook portion  40  into the hole portion  24   f,  temporary attaching and positioning of the lower stiffener  30  is attained when the lower stiffener  30  is assembled to the beam member  24 . 
     As shown in  FIGS.  4 ,  5  and  6 A- 6 C , there are provided ribs  41  which connect the front end of the front end portion  34  and the front end of the body portion  33 . As shown in  FIG.  6 C , the rib  41  comprises a front piece, a rear piece, a lower piece, and an upper piece, the front piece of the rib  41  contacts a back face of the front piece portion  39 , the rear piece of the rib  41  contacts a front face of the rear-side inclination piece portion  37 , the lower piece of the rib  41  contacts an upper face of the front-side inclination piece portion  38 , and the upper piece of the rib  41  is inclined such that its front side is located at the higher level than its rear side so as to connect the upper end of a front piece portion  39  and the front end of the body portion  33 . 
     As shown in  FIG.  4   , the plural ribs  41  are provided at the lower stiffener  30  at intervals in the vehicle width direction with a prescribed distance between the two. Thereby, the front end portion  34  is configured to have the high rigidity with a simple structure. 
     Herein, the lower stiffener  30  is configured to control a reaction force to the pedestrian by means of the high-rigidity front end portion  34  which performs a function of receiving the load and the body portion  33  which performs a function of deformation. 
     As shown in  FIG.  5    which is an enlarged view of the central portion, in the vehicle width direction, of  FIG.  4   , the rib  41  which is provided at a position, in the vehicle width direction, of the front end portion  34  which corresponds to the central portion  27  of the beam member  24  is configured to extend obliquely outwardly-and-rearwardly in the plan view. Herein, in  FIG.  5   , an obliquely-extending direction of each of the ribs  41  is illustrated by an imaginary extension line for clarification. 
     Thus, by configuring the rib  41  provided at the position, in the vehicle width direction, of the front end portion  34  which corresponds to the central portion  27  of the beam member  24  to extend obliquely outwardly-and-rearwardly in the plan view, the rib  41  is crushed completely. If this rib is configured to extend straightly in the longitudinal direction, the rib resists the vehicle-frontal collision load to a considerably-large extent, so that this rib may not be crushed completely, that is, part of the rib may remain uncrushed. Meanwhile, since the rib  41  of the present embodiment is inclined relative to the vehicle longitudinal direction as described above, falling down of the rib  41  is promoted, so that the rib&#39;s complete crushing is promoted. 
     Specifically, the ribs  41  which are positioned on the right side, in the vehicle width direction, of a center line  30 CL, in the vehicle width direction, of the lower stiffener  30  extend obliquely rightwardly-and-rearwardly, whereas the ribs  41  which are positioned on the left side, in the vehicle width direction, of the center line  30 CL, in the vehicle width direction, of the lower stiffener  30  extend obliquely leftwardly-and-rearwardly. Thereby, the ribs  41  are configured such that the rib&#39;s complete crushing is promoted. 
     As shown in  FIGS.  2 ,  3  and  6 C , the body portion  33  of the lower stiffener  30  is configured to have a liner shape extending in the vehicle longitudinal direction, and lower ribs  42  which connect the vertical face portion  31  including the fixation portions  32  and the front end portion  34  are provided at a lower face of the body portion  33  of the lower stiffener  30 . In the present embodiment, the plural lower ribs  42  which respectively connect the front end portion  34  and the vertical face portion  31  in the vehicle longitudinal direction are provided at intervals in the vehicle width direction at the lower face of the body portion  33  at respective positions which correspond to the both-end portions  28  of the bead member  24  in the vehicle longitudinal direction. 
     Herein, at a position where an under-cover attachment portion described later (see reference number  43  shown in  FIGS.  7  and  8   ) is provided, the lower ribs  42  are provided at the lower face of the body portion  33  such that they connect the front end portion  34  and the under-cover attachment portion  43  in the vehicle longitudinal direction. 
     Thereby, the reaction force in the pedestrian&#39;s protection is adjusted by the lower ribs  42 . Specifically, the reaction force in the pedestrian&#39;s protection can be adjusted by changing the number of the lower ribs  42  or the thickness of the lower ribs  42 . Further, since the rigidity of the body portion  33  is improved by the lower ribs  42 , the body portion  33  is securely deflected downwardly without buckling or bending in the vehicle frontal collision. 
     Further, as shown in  FIG.  6 C , a lower end of the lower rib  42  is located at the higher level than a lower end of the front-end-portion lower section  34 L of the front end portion  34 . Thereby, the rotation of the front end portion  34  in the vehicle frontal collision is not hindered by the lower rib  42 . Further, the collision reaction force in the pedestrian protection is adjusted by the lower rib  42 . 
     The under-cover attachment portions  43  which extend downwardly are provided at the base portion of the body portion  33  of the lower stiffener  30  as shown in  FIGS.  2  and  3   . As shown in the same figures, the under-cover attachment portions  43  are provided at intervals in the vehicle width direction. 
     As shown in  FIGS.  7  and  8   , the under-cover attachment portion  43  comprises a pair of right-and-left side walls  43   a,    43   a  which face each other in the vehicle width direction with a prescribed distance, a front wall  43   b  which interconnects respective front end portions of the right-and-left side walls  43   a  in the vehicle width direction, and a bottom wall  43   c  which interconnects respective lower end portions of the right-and-left side walls  43   a  in the vehicle width direction. 
     The under-cover attachment portion  43  is formed by the above-described respective walls  43   a,    43   b,    43   c  in a boxy shape which is opened forwardly and upwardly. Also, the bottom wall  43   c  of the under-cover attachment portion  43  becomes an attaching (mounting) seat for attaching an under cover  50  shown in  FIGS.  10 - 13   . 
     As shown in  FIGS.  6 C,  7  and  8   , a notch  44  is formed at a base portion of the under-cover attachment portion  43 . As shown in  FIGS.  7  and  8   , this notch  44  is formed such that a lower side of the above-described vertical face portion  31  is cutout partially, corresponding to an upper side between the pair of right-and-left side walls  43   a  of the under-cover attachment potion  43 . 
     Thereby, since the notch  44  becomes a fragile portion, the body portion  33  is bent downwardly with a supporting point of the base portion, i.e., a root portion, of the body portion  33  because the notch  44  becomes a bending causing point. Thereby, a position where a tip-side part of the body portion  33  remains uncrushed is moved downwardly. 
     Herein, as shown in  FIG.  4   , the protrusion face portion  35  is provided at a part of the vertical face portion  31 , and comprises an upper wall  35   a  and right-and-left side walls  35   b ,  35   b  such that it is formed in a boxy shape. In other words, the protrusion face portion  35  is formed at the vertical face portion  31  via the upper wall  35   a  and the right-and-left side walls  35   b,    35   b  such that it is forwardly spaced apart from the vertical face portion  31 . As shown in  FIGS.  7  and  8   , a vehicle rearward side and a vehicle downward side of the protrusion portion  35  are opened. 
     Further, as shown in  FIG.  6 B , the protrusion face portion  35  comprises a protrusion-face-portion upper section  35 U which is located at the higher level than an upper end of the front-end-portion upper section  34 U and a protrusion-face-portion lower section  35 L which is located at a lower level than an upper end of the front-end-portion upper section  34 U. In the present embodiment, as shown in  FIG.  6 B , the protrusion-face-portion lower section  35 L is set at the same level, in the vehicle vertical direction, as the front-end-portion upper section  34 U. 
     The protrusion-face-portion lower section  35 L is configured to have the lower strength against the collision load from the vehicle forward side than the protrusion-face-portion upper section  35 U. Specifically, as shown in  FIG.  6 B,  7  and  8   , plural ribs  45  extending in the vertical direction are arranged in an upper area of the above-described boxy shape (i.e., an area of the protrusion-face-portion upper section  35 U), and a lower area of the boxy shape is configured to be a hollow  46 . 
     Thereby, even if the front end portion  34  is retreated by the rearward load and the front-end-portion lower section  34 L remains uncrushed partially, the front face of the beam member  24  is moved back just straightly by the protrusion-face-portion upper section  35 U of the protrusion face portion  35  protruding forwardly, so that the beam member  24  is suppressed from being rotated. 
     Further, by arranging the vertical rib  45  in the upper area of the boxy shape and forming the hollow  46  in the lower area of the boxy shape, the protrusion-face-portion lower section  35 L is configured such that it has the lower strength against the collision load from the vehicle forward side than the protrusion-face-portion upper section  35 U with a simple structure. 
     As shown in  FIGS.  7  and  8   , the plural vertical ribs  45  are provided at intervals in the vehicle width direction. Further, the vertical ribs  45  extend downwardly from the upper wall  35   a  of the protrusion face portion  35  and supported by a lateral crosspiece  47  which extends laterally between the right-and-left side walls  35   b,    35   b  at their lower portions. 
     As shown in  FIG.  4   , the protrusion face portion  35  is provided, in the vehicle width direction, at a location of the lower stiffener  30  which corresponds to an area between a border portion β between the central portion  27  and each of the both-end portions  28  of the beam member  24  and an inward-side end position, in the vehicle width direction, of the lower-side crash can  23 . In the present embodiment, the protrusion face portion  35  is provided, in the vehicle width direction, at a location adjacent to the inward-side end position, in the vehicle width direction, of the lower-side crash can  23 . 
     Thereby, since the protrusion face portion  35  hits against a barrier BRA earlier than the vertical face portion  31  when the barrier BRA intrudes in a collision mode determined by the MPDB collision test (see  FIG.  9   ), the crushing is controllable. 
     As shown in  FIGS.  4  and  9   , a central portion, in the vehicle width direction, of the boxy shape of the protrusion face portion  35  protrudes forwardly as a central protrusion portion  35   c . Thereby, in the vehicle frontal collision, the portion protruding forwardly (see the central protrusion portion  35   c ) previously hits against the barrier BAR (see  FIG.  9   ), so that the front face of the protrusion face portion  35  is crushed substantially uniformly. 
     Meanwhile, as shown in  FIGS.  6 A- 6 C , the front end portion  34  comprises the front-end-portion upper section  34 U which is located above the body portion  33  and the front-end-portion lower section  34 L which is located below the body portion  33 . The front-end-portion upper section  34 U is positioned on the vehicle forward side of the front-end-portion lower section  34 L and protrudes highly relative to the body portion  33 . 
     Thereby, in the vehicle frontal collision, the upper end of the front end portion  34  is rotated such that its rear side is moved more downwardly, so that the body portion  33  is deflected downwardly. Consequently, the part of the front end portion  34  which remains uncrushed is moved below the vertical face portion  31 . 
       FIG.  10    is a schematic side view showing deformation at a first stage in the vehicle frontal collision,  FIG.  11    is a schematic side view showing deformation at a second stage in the vehicle frontal collision,  FIG.  12    is a schematic side view showing deformation at a third stage in the vehicle frontal collision, and  FIG.  13    is a schematic side view showing deformation at a fourth stage in the vehicle frontal collision. Hereafter, the respective deformations in the vehicle frontal collision will be described referring to  FIGS.  10 - 13   . 
     &lt;Deformation at First Stage Shown in  FIG.  10   &gt; 
     At the first stage of the vehicle frontal collision, the frontal-collision load is inputted to the front-end-portion upper section  34 U earlier than the front-end-portion lower section  34 L of the front end portion  34  of the lower stiffener  30 , the upper end of the front end portion  34  is rotated with a support point of the border portion a such that its rear side is moved more downwardly as shown by an arrow a in  FIG.  10   , and this moment causes the body portion  33  to be deflected downwardly as shown by an arrow b in  FIG.  10   . 
     &lt;Deformation at Second Stage Shown in  FIG.  11   &gt; 
     Since the base portion of the body portion  33  of the lower stiffener  30  is configured to be fragile by forming the notch  44 , at the second stage of the vehicle frontal collision, as shown in  FIG.  11   , the body portion  33  is bend downwardly with the support point of the base portion, i.e., the root portion, of the body portion  33 , so that the position of the front end portion  34  which remains uncrushed is moved downwardly. Further, the under-cover attachment portion  43  is rotated rearwardly with the support point of the part where the notch  44  is formed so as not to hinder the downward move of the body portion  33 . 
     &lt;Deformation at Third Stage Shown in  FIG.  12   &gt; 
     Since members (see the protrusion face portion  35  and the vertical ribs  45  of the upper section  35 U) which are substantially equivalent to the uncrushed-remaining degree of the front end portion  34  of the lower stiffener  30  moving rearwardly is provided at the rear portion of the lower stiffener  30 , at the third stage of the vehicle frontal collision, the uncrushed-remaining degree of the front-face side of the beam member  24  becomes substantially uniform as show in  FIG.  12   . 
     &lt;Deformation at Fourth Stage Shown in  FIG.  13   &gt; 
     The above-described uniformizing moves back the beam member  24  just straightly and axially compresses the lower-side crash can  23 , thereby absorbing the collision energy properly. 
     In the drawings, an arrow F shows the vehicle forward side, an arrow R shows the vehicle rearward side, an arrow IN shows the inward side in the vehicle width direction, and an arrow OUT shows the outward side in the vehicle width direction, and an arrow UP shows the vehicle upward side. 
     As described above, the front structure of the vehicle according to the present embodiment comprises the beam member  24  positioned in front of the sub frame  14  and having the closed-cross sections  25 ,  26  extending in the vehicle width direction, and the plate member (the lower stiffener  30 ) extending forwardly from the beam member  24 , wherein the plate member (the lower stiffener  30 ) comprises the fixation portions  32  fixed to the beam member  24 , the body portion  33  extending forwardly from the fixation portions  32 , and the front end portion  34  positioned at the front end of the body portion  33  and configured to have the higher rigidity against the load applied in the longitudinal direction than the body portion  33 , the front end portion  34  of the plate member (the lower stiffener  30 ) comprises the upper section (the front-end-portion upper section  34 U) located at the higher level than the body portion  33  and the lower section located (the front-end-portion lower section  34 L) at the lower level than the body portion  33 , and the upper section (the front-end-portion upper section  34 U) is positioned on the vehicle forward side of the lower section (the front-end-portion lower section  34 L) (see  FIGS.  1 - 3  and  6 A- 6 C ). 
     According to this structure, even if the vehicle collides against the pedestrian from any direction, the front end portion  34  transmits the collision load to the body portion  33  so as to allow the body portion  33  to be deformed with a constant load. Thereby, an appropriate reaction force can be generated. 
     Further, in the vehicle frontal collision, since the load input happens at the upper section (the front-end-portion upper section  34 U) of the front end portion  34  earlier than the lower section (the front-end-portion lower section  34 L), there occurs the moment to cause the upper end of the front end portion  34  to rotate such that its rear side is moved more downwardly, so that the body portion  33  is deflected (bent) downwardly. Thereby, the body portion  33  can be suppressed from being crushed at the front face of the beam member  24 . That is, even if the plate member (the lower stiffener  30 ) is applied to the beam member  24  having the closed-cross sections  25 ,  26 , the pedestrian-protection performance and the vehicle-parts damage suppression in the vehicle light collision can be compatibly attained. 
     Further, in the present embodiment, the front end portion  34  comprises the lower section (the front-end-portion lower section  34 L) which protrudes downwardly from the front end of the body portion  33  and the upper section (the front-end-portion upper section  34 U) which is positioned at the front end of the lower section (the front-end-portion lower section  34 L) (see  FIG.  6 A- 6 C ). 
     According to this structure, the border portion a between the body portion  33  and the lower section (the front-end-portion lower section  34 L) becomes the bending causing point to cause the rotation of the front end portion  34  in the vehicle frontal collision by its bending. 
     Moreover, in the present embodiment, the ribs  41  which connect the front end of the front end portion  34  and the body portion  33  are provided (see  FIG.  6 C ). 
     According to this structure, the front end portion  34  can be configured to have the high rigidity with a simple structure. 
     Also, in the present embodiment, the beam member  24  comprises the central portion  27  which is positioned at the central side, in the vehicle width direction, of the beam member  24  and extends in the vehicle width direction and the both-end portions  28  which are positioned on the both sides, in the vehicle width direction, of the central portion  27  and configured to extend obliquely outwardly-and-rearwardly from the both-side ends of the central portion  27  in the plan view, and the ribs  41  which are provided at the position, in the vehicle width direction, of the front end portion  34  which corresponds to the central portion  27  of the beam member  24  are configured to extend obliquely outwardly-and-rearwardly in the plan view (see  FIGS.  4  and  5   ). 
     According to this structure, since the ribs  41  provided at the position, in the vehicle width direction, of the front end portion  34  which corresponds to the central portion  27  extend obliquely outwardly-and-rearwardly in the plan view, the ribs  34  are crushed completely. If this ribs are configured to extend straightly in the longitudinal direction, the ribs resist the vehicle-frontal collision load to a considerably-large extent, so that these ribs are not crushed completely, that is, a part of each rib remains uncrushed. Meanwhile, since the rib  41  of this embodiment is inclined relative to the vehicle longitudinal direction as described above, falling down of the rib  41  is promoted, so that the rib&#39;s complete crushing can be promoted. 
     Additionally, in the present embodiment, the front end portion  34  is configured to have the forwardly-inclined shape (see  FIG.  6 C ). 
     According to this structure, the moment to cause the upper end of the front end portion  34  to rotate such that its rear side is moved more downwardly becomes larger, so that the downward deflection of the body portion  33  can be secured. Moreover, the stroke of the rearward rotation of the front end portion  34  can be secured sufficiently, so that the front end portion  34  can be suppressed from interfering with the body portion  33 , thereby allowing the sufficient rotation of the front end portion  34 . 
     Further, in the present embodiment, the body portion  33  is configured to have the liner shape, and the lower ribs  42  which connect the fixation portion  32  and the front end portion  34  are provided at the lower face of the body portion  33  (see  FIG.  6 C ). 
     According to this structure, the reaction force in the pedestrian&#39;s protection can be adjusted by the lower ribs  42 . Further, since the rigidity of the body portion  33  is improved by the lower ribs  42 , the body portion  33  can be securely deflected downwardly without buckling or bending in the vehicle frontal collision. 
     Moreover, in the present embodiment, the lower end of the lower rib  42  is located at the higher level than the lower end of the lower section (the front-end-portion lower section  34 L) (see  FIG.  6 C ). 
     According to this structure, the rotation of the front end portion  34  in the vehicle frontal collision is not hindered by the lower ribs  42 . Further, the collision reaction force in the pedestrian protection can be adjusted by the lower ribs  42 . 
     Additionally, in the present embodiment, the under-cover attachment portion  43  is provided at the base portion of the body portion  33  such that the under-cover attachment portion  43  extends downwardly from the base portion of the body portion  33 , and the notch  44  is formed at the base portion of the under-cover attachment portion  43  (see  FIGS.  6 C,  7  and  8   ). 
     According to this structure, since the notch  44  becomes the fragile portion, the body portion  33  can be bent downwardly with the supporting point of the base portion, i.e., the root portion, of the body portion  33  because the notch  44  becomes the bending causing point. Thereby, the position where the tip-side part of the body portion  33  remains uncrushed can be moved downwardly. 
     In correspondence of the present invention to the above-described embodiment, the plate member of the present invention corresponds to the lower stiffener  30  of the embodiment. Likewise, the upper section corresponds to the front-end-portion upper section  34 U, and the lower section corresponds to the front-end-portion lower section  34 L. However, the present invention is not to be limited to the above-described embodiment. 
     For example, while the engine-driven vehicle provided with the engine room is exemplified in the embodiment, the present invention is applicable to an electric vehicle provided with a motor room. 
     As described above, the present invention is useful for the front structure of the vehicle which comprises the beam member positioned in front of the sub frame and having the closed-cross section extending in the vehicle width direction and the plate member extending forwardly from the beam member.