JP5391397B2 - Vehicle lower structure - Google Patents

Description

  The present invention relates to a vehicle lower structure applied to a vehicle.

  Conventionally, it has been required to construct a compact vehicle having sufficient vehicle body rigidity while ensuring occupant comfort.

  In Patent Document 1, a first kick-up portion and a second kick-up portion that are stepped upward at different heights are juxtaposed behind a floor panel (floor pan) and have a closed cross-sectional structure extending in the vehicle width direction. A cross member is provided in the second kick-up section, and a plurality of passenger seats are arranged in parallel above and below each of the first kick-up section and the second kick-up section. A lower vehicle body structure of a vehicle that is compatible with ensuring of vehicle body rigidity is schematically disclosed by a simplified drawing.

JP 2006-290140 A

  However, if the lower body structure of a vehicle described in Patent Document 1 is to be adopted, there is a situation that the shape of the cross member becomes an arch shape. This point will be described below with reference to FIGS.

  FIG. 7 is a perspective view of a conventional vehicle lower structure 900. FIG. 8 is a front view of a conventional vehicle lower structure 900. FIG. 9 is an end view taken along the line U-U in FIG. 8. 10 is an end view taken along the line VV of FIG. Customers' needs for automobiles are diverse, such as improved fuel economy, increased navigation distance, improved passenger cabin comfort, and increased cargo space capacity. In the process of meeting such needs, the fuel tank 901 has been disposed below the floor pan 910. And in order to increase the capacity | capacitance of the fuel tank 901, the shape of the fuel tank 901 has been changed into what has the tank protrusion 902 which protrudes ahead of a vehicle so that it may enter into the floor pan inclination part 911 of the floor pan 910. FIG. Further, in order to fix the fuel tank 901 below the floor pan 910 with a small number of members, the fuel tank holding arm 903 is fastened and fixed to the cross member 904 by setting a tank fastening bracket (not shown). The tank holding arm 903 holds the front portion of the fuel tank 901. In addition, the cross member 904 also plays a role of receiving the load of the rear seat 905 and a passenger (not shown) sitting on the rear seat 905.

  As shown in FIG. 7, the cross member 904 prevents the trailing arm mounting bracket 908 from being twisted. The trailing arm mounting bracket 908 is included in the side member 906 and holds the trailing arm 907. In this way, the cross member 904 connects the side members 906 to increase the rigidity of the entire vehicle. However, under the conventional layout design concept based on the assumption that a fuel tank 901 protruding from the front side and having a tank protrusion 902 is formed, an arched cross member 904 as shown in FIG. 8 is adopted. The cross member 904 must be connected by passing over the fuel tank 901.

  In such a layout design philosophy, the inventor mounted a hybrid battery on a compact car with a smaller vehicle size than before without reducing the cargo space capacity, and the motor drive by the hybrid battery and the fuel tank We had the opportunity to design and design a hybrid car that would run in combination with the engine driven by other fuels. Then, the inventor considered to arrange the hybrid battery that has been arranged in the luggage compartment so far in a space formed below the rear seat and above the floor pan 910 and in front of the floor pan inclined portion 911. The entire structure of the vehicle substructure was reviewed. In this review, the inventor decided that the cross member 904 is formed in an arch shape, so that the rigidity of the cross member 904 is weakened, and the lateral load input from the connecting point with the trailing arm mounting bracket 908 It has been found that the cross member 904 is easy to fall inward.

  FIG. 11 is a plan view showing a virtual vehicle lower structure 950. Here, the inventor has two examples in which the side members 906 are connected to each other by making the shape of the cross member linear so as to increase the rigidity of the force applied to the side member 906 with respect to the lateral load input from the trailing arm 907. Thought. The first example is arranged to connect load input points 951 to which a lateral load is input from the cross member indicated by reference numeral “952” in FIG. 11, that is, the trailing arm 907 in the trailing arm mounting bracket 908. This is a linear cross member 952. The second example is a cross member indicated by reference numeral “954” in FIG. 11, that is, a request for attaching a hybrid battery (not shown) to the cross member, so that the fuel tank 901 (see FIGS. 7 to 10) A travel battery attachment point 953 is set in the vicinity, and the cross member 954 is a linear cross member that extends in the vehicle width direction through the attachment point 953 and connects the side members 906 to each other. However, in the first example, the capacity of the fuel tank 901 must be greatly reduced. Further, in the second example, the attachment location of the cross member 954 and the side member 906 is significantly changed, and the displacement of each part of the vehicle due to various loads input to the vehicle is greatly changed. Forced to make changes.

  The present invention has been made in view of the above points, and an object of the present invention is to increase the rigidity of a vehicle while minimizing the number of changes in accordance with an actual vehicle design.

The vehicle lower structure of the present invention includes a side member provided on each side in the vehicle width direction including a trailing arm mounting bracket that holds an end of the trailing arm,
A cross member connecting the trailing arm mounting brackets with a long length extending in the vehicle width direction;
A fuel tank disposed in a space area on the vehicle rear side surrounded by each of the trailing arm mounting bracket and the cross member;
With
A lower cross portion protruding from the lower end of the cross member toward the front of the vehicle;
The fuel tank has an attachment projecting portion attached to the lower cross portion that projects from the vehicle front portion to the vehicle front side at a lower portion thereof,
The front surface of the fuel tank includes a flat region extending forward in the vehicle width direction toward the front of the vehicle,
The cross member is
A straight portion that is located in front of the vehicle with respect to the flat region, extends in the vehicle width direction, and looks like a horizontally long rectangular shape when viewed from the vehicle front side,
A connecting portion extending in the vehicle width direction from the straight portion and connected to each of the trailing arm mounting brackets;
And a battery mounted on the lower cross portion so as to face the flat region of the fuel tank .

  According to the present invention, the rigidity of the entire cross member is increased by the straight portion despite the minimal design change in which the cross member is provided with the straight portion, and the lateral load due to the lateral displacement of the trailing arm is not affected by the cross member. Therefore, the cross member is prevented from being overturned, the applied force rigidity is improved, and the rigidity of the entire vehicle is increased.

It is a typical top view of a vehicle lower part structure. It is a perspective view of a vehicle lower part structure. It is a front view of a vehicle lower part structure. It is an AA line end view of FIG. FIG. 4 is an end view taken along line BB in FIG. 3. It is side surface sectional drawing which shows how to attach the hybrid battery to a vehicle lower part structure. It is a perspective view of the conventional vehicle lower part structure. It is a front view of the conventional vehicle lower part structure. FIG. 9 is an end view taken along the line U-U in FIG. 8. It is the VV line end view of FIG. It is a top view which shows a virtual vehicle lower part structure.

  One embodiment will be described with reference to FIGS. The present embodiment is an application example to a hybrid car on which a fuel tank and a hybrid battery are mounted and travels using both a motor drive by the hybrid battery and an engine drive by the fuel in the fuel tank.

  FIG. 1 is a schematic plan view of the vehicle lower structure 100. First, the outline of the vehicle lower structure 100 of the present embodiment will be described based on FIG. The vehicle lower structure 100 includes a side member 101, a cross member 102, and a fuel tank 103.

  The side members 101 are provided on both sides of the side member 101 in the vehicle width direction and extend in the front-rear direction of the vehicle. Each side member 101 includes a trailing arm mounting bracket 104. The trailing arm mounting bracket 104 is a member having a U-shaped cross section in plan view, and is attached to the side member 101 with the U-shaped opening side portion facing the rear of the vehicle. The trailing arm mounting bracket 104 holds a bush 106 (see FIG. 2) forming an end of the trailing arm 105 (see also FIG. 2) in contact with the U-shaped inner surface. Further, an ear 104a (see also FIGS. 2 and 3) for spot welding the connecting portion 122 extends from the end of the trailing arm mounting bracket 104 located on the vehicle inner side toward the vehicle inner side. Yes.

  The cross member 102 is a long member extending in the vehicle width direction. Both ends of the cross member 102 are connected to the respective trailing arm mounting brackets 104. In this manner, the cross member 102 connects the two trailing arm mounting brackets 104 to increase the rigidity of the entire vehicle. The cross member 102 includes a center cross member 102a shown on the lower side (front side of the vehicle) in FIG. 1, a rear cross member 102b shown on the upper side (front side of the vehicle) in FIG. 1, and a center cross member 102a. And a front cross member (not shown) located on the front side of the vehicle. Here, the center cross member 102a corresponds to a “cross member” in the claims.

  The fuel tank 103 is disposed in a space area SP on the vehicle rear side surrounded by each trailing arm mounting bracket 104 and the center cross member 102a. The boundary of the space area SP on the vehicle rear side is defined by the rear cross member 102b.

  FIG. 2 is a perspective view of the vehicle lower structure 100. FIG. 3 is a front view of the vehicle lower structure 100. FIG. 4 is an end view taken along line AA in FIG. FIG. 5 is an end view taken along line BB of FIG. In FIG. 2, the floor pan 110 is omitted. In FIGS. 2 and 5, the hybrid battery 127 (described later) is omitted. 2 and 3, the rear seat 126 (described later) is omitted.

  A floor pan 110 is attached to the cross member 102. The floor pan 110 forms a floor pan inclined portion 112 that inclines so that the rear is upward at an angle that is substantially perpendicular to the front surface 111 of the fuel tank 103. The floor pan 110 also forms a lower floor portion 113 extending from the lower end of the floor pan inclined portion 112 to the front of the vehicle. The floor pan 110 also forms an upper floor portion 114 that extends rearward from the upper end of the floor pan inclined portion 112. A spare tire storage portion 115 for storing a spare tire (not shown) is provided in the upper floor portion 114 on the vehicle rear side of the rear cross member 102b. Further, both side portions of the floor pan 110 in the vehicle width direction are joined to the side member 101. Such a floor pan 110 serves as a boundary between a space that becomes a passenger compartment or a cargo compartment above the floor pan 110 and a space in which the fuel tank 103 below the floor pan 110 is disposed.

  The trailing arm mounting bracket 104 included in the side member 101 holds the bush 106 on its U-shaped inner surface. A load input from a tire (not shown) of a traveling vehicle is input to the bush 106 via the trailing arm 105. At least a part of the load input to the bush 106 is transmitted to the trailing arm mounting bracket 104.

  A fuel pump 116 is attached to the upper surface of the fuel tank 103. Two fuel tank mounting brackets 108 are provided above the fuel tank 103 and on the vehicle rear side of the fuel pump 116. Each of the fuel tank mounting brackets 108 protrudes from the fuel tank 103 to the vehicle rear side, and is aligned in the vehicle width direction. Here, a bracket 109 is welded to a position corresponding to the fuel tank mounting bracket 108 on the lower surface of the rear cross member 102b. The fuel tank mounting bracket 108 is fastened to the bracket 109 by bolts and nuts 118.

  In addition, a flat region 117 is formed on the front surface 111 of the fuel tank 103 so as to face the front of the vehicle and extend flat in the vehicle width direction. Two mounting protrusions 107 are provided at a location below the flat region 117 in the front portion of the vehicle in the fuel tank 103. Each of the attachment protruding portions 107 protrudes from the fuel tank 103 toward the vehicle front side, and is arranged in the vehicle width direction. The mounting protruding portion 107 contacts the lower surface of the lower cross portion 119 (described later). The attachment protruding portion 107 is fastened to the lower cross portion 119 by a bolt nut 120 (described later).

  Here, the center cross member 102a will be described. The straight portion 121 is the basis of the center cross member 102a. The straight portion 121 is a long member extending in the vehicle width direction. The straight portion 121 is located in front of the vehicle with respect to the flat region 117 formed on the front surface 111 of the fuel tank 103. The upper part of the straight part 121 is bent so as to incline upward toward the rear of the vehicle. The straight portion 121 looks like a horizontally long rectangular shape when viewed from the front side of the vehicle.

  The center cross member 102 a has a connecting portion 122. The connecting portion 122 extends outward in the vehicle width direction from each of both ends in the vehicle width direction of the straight portion 121, and is smoothly bent toward the vehicle rear side, and at its tip, the ear portion 104a of the trailing arm mounting bracket 104 is provided. It is joined to spot welding. Therefore, the center cross member 102 a receives a load from the trailing arm mounting bracket 104.

  By the way, the height of the lower end of the connection part 122 and the height of the lower end of the straight part 121 correspond. Further, the height of the connecting portion 122 is higher than the height of the straight portion 121. An arch portion 124 is disposed above the straight portion 121. The arch portion 124 is a member that is curved so as to be convex upward in a front view and extends linearly in the vehicle width direction in a plan view, and is sandwiched between the connecting portions 122 so as to be more forward of the vehicle than the flat region 117. To position. There is an opening between the arch portion 124 and the straight portion 121. When the vehicle lower structure 100 is viewed from the front side of the vehicle, the front surface 111 of the fuel tank 103 can be seen between the arch portion 124 and the straight portion 121.

  A rear seat 126 is attached to the floor pan 110 at a location above the arch portion 124. The rear seat 126 protrudes forward from the floor pan inclined portion 112, and forms a U-shaped space in side view together with the rear seat 126 and the floor pan inclined portion 112. In this space, a hybrid battery 127 for supplying power to a vehicle driving motor (not shown) is installed.

  FIG. 6 is a side sectional view showing how to attach the hybrid battery 127 to the vehicle lower structure 100. The hybrid battery 127 is placed on the lower cross portion 119 (described below) via the lower floor portion 113, and the fastening leg portion 127a, the lower floor portion 113, and the lower floor portion 113 of the lower portion of the hybrid battery 127 are provided. The battery fastening bracket 127b located on the lower surface is fixed so as not to move by fastening with the bolt nut 127c. In the present embodiment, the vehicle (automobile) is driven by a vehicle driving motor that is driven by being supplied with power from the hybrid battery 127, and an engine engine that is driven by being supplied with fuel (not shown) from the fuel tank 103. (It is realized by the combined use with (not shown)). In such a vehicle, even if the fuel tank 901 is not provided with the tank protrusion 902 as in the prior art shown in FIGS. The command will be realized.

  From the lower end of the center cross member 102a, the lower cross portion 119 protrudes forward of the vehicle. The lower cross part 119 is provided over all the connecting parts 122 and the straight part 121. An attachment urging portion 107 (described above) provided in the fuel tank 103 is in contact with the lower surface of the lower cross portion 119. The lower cross portion 119 and the attachment protruding portion 107 are fastened by a bolt and nut 120.

  In the side member 101 configured as described above, when a vehicle (automobile) travels, a load input from a tire (not shown) of the traveling vehicle via the trailing arm 105 is input to the bush 106. Is done. When a load is applied to the bush 106 and the bush 106 vibrates, the load is input to the trailing arm mounting bracket 104 included in the side member 101. As a result, the lateral load from the trailing arm mounting bracket 104 is input to the center cross member 102a.

  Here, in the side member 101 according to the present embodiment, the rigidity of the vehicle is increased and the trailing arm is attached by a minimum change in accordance with the actual vehicle design in which a part of the center cross member 102a is a straight portion 121. It is possible to suppress the inversion of the center cross member 102a due to the lateral load being input from the bracket 104 to the connecting portion 122. The inventor conducted experiments using the side member 101 shown in FIG. 2, and the torsional rigidity of the side member 101 having the straight portion 121 is 139% of the torsional rigidity of the side member 101 not having the straight portion 121. I have confirmed that.

  Further, in the side member 101 of the present embodiment, the fuel tank 103 has an attachment protruding portion 107, and this attachment protruding portion 107 is directly attached to the lower cross portion 119 of the cross member 102. That is, in the side member 101 of the present embodiment, the fuel tank holding arm 903 is not used as in the prior art shown in FIGS. 7 to 10. For this reason, the number of parts to be mounted on the vehicle is reduced, The vehicle can be reduced in weight.

  Furthermore, in the side member 101 of the present embodiment, the hybrid battery 127 is installed below the rear seat 126, and the weight of the hybrid battery 127 is received by the lower cross portion 119. For this reason, the center of gravity of the entire vehicle comes near the center of the vehicle, and the traveling of the vehicle (automobile) is stabilized.

DESCRIPTION OF SYMBOLS 100 Vehicle lower structure 101 Side member 102 Cross member 103 Fuel tank 104 Trailing arm mounting bracket 105 Trailing arm 106 Bush (end of trailing arm)
107 Extrusion part for mounting 117 Flat area 119 Lower cross part 121 Straight part 122 Connecting part SP Spatial area

Claims (2)

A side member provided on each side in the vehicle width direction, including a trailing arm mounting bracket for holding an end of the trailing arm;
A cross member connecting the trailing arm mounting brackets with a long length extending in the vehicle width direction;
A fuel tank disposed in a space area on the vehicle rear side surrounded by each of the trailing arm mounting bracket and the cross member;
With
A lower cross portion protruding from the lower end of the cross member toward the front of the vehicle;
The fuel tank has an attachment projecting portion attached to the lower cross portion that projects from the vehicle front portion to the vehicle front side at a lower portion thereof,
The front surface of the fuel tank includes a flat region extending forward in the vehicle width direction toward the front of the vehicle,
The cross member is
A straight portion that is located in front of the vehicle with respect to the flat region, extends in the vehicle width direction, and looks like a horizontally long rectangular shape when viewed from the vehicle front side,
A connecting portion extending in the vehicle width direction from the straight portion and connected to each of the trailing arm mounting brackets;
A battery mounted on the lower cross portion so as to face the flat region of the fuel tank;
Vehicle lower structure. The battery is installed below the rear seat,
The vehicle lower structure according to claim 1.

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