JP7567494B2 - Vehicle underbody structure - Google Patents

Description

The present invention relates to a vehicle undercarriage structure.

Vehicles such as automobiles have a vehicle undercarriage that includes a suspension fixing part to which a swinging suspension for the rear wheels is fixed, and a rear side member that extends from the rear end of the vehicle toward the front of the vehicle and is connected to the suspension fixing part.

In such a vehicle undercarriage structure, when the vehicle is traveling, for example due to lateral acceleration (lateral G) when the vehicle turns, the rear side member receives a load in the direction of the suspension's swing axis from the suspension fixing part, causing the rear side member to vibrate in the swing axis direction. When the rear side member vibrates in the swing axis direction, this vibration causes torsional vibration of the vehicle body and floor vibration of the floor panel.

In addition, in the vehicle undercarriage structure, one of the front, rear, left and right wheels may receive a vertical load, such as the inertial force of the vehicle acting on the outer wheel when the vehicle turns. In such cases, torsional vibration occurs with the maximum amplitude point being the underside of the floor panel on the wheel side diagonally opposite the wheel receiving the load. This torsional vibration includes a vertical vibration component and a lateral vibration component. In the vehicle undercarriage structure, these vibrations cause the underside of the floor to vibrate, making it difficult to improve the vehicle's NV (Noise and Vibration) characteristics and handling stability (maneuverability).

Patent Document 1 describes a suspension support structure for an automobile. This support structure includes a bending member 13 that bends toward the side sill 2 at the front end of the rear frame 12, and a torque box 43. The torque box 43 is disposed behind the bending member 13 and connects the rear frame 12 and the side sill 2. Furthermore, in this support structure, these members have a closed cross-sectional structure, and a trailing arm 7 that constitutes the rear suspension is fixed to the bottom surface by a support bracket 6. In this way, this structure increases the support rigidity of the support bracket 6 in the fore-and-aft direction of the vehicle body.

Patent No. 4349039

In the support structure of Patent Document 1, vibrations in the swing axis direction of the rear suspension are transmitted from the trailing arm 7 to the rear frame 12 via the support bracket 6, bending member 13, and torque box 43 due to lateral acceleration (lateral G) when the vehicle turns. With such a support structure, there is a risk that these vibrations will cause torsional vibrations of the vehicle body and floor vibrations of the floor panel.

In addition, in the support structure of Patent Document 1, when vibrations having a vibration component in the vehicle width direction occur in the rear frame 12, no special measures are taken to efficiently disperse the vibrations. Therefore, it is difficult to say that the support structure of Patent Document 1 maintains good NV characteristics and handling stability of the vehicle.

In view of these problems, the present invention aims to provide a vehicle underbody structure that can suppress torsional vibrations of the floor panel and improve the vehicle's noise and vibration characteristics and handling stability.

In order to solve the above problems, a representative configuration of the vehicle understructure according to the present invention is a vehicle understructure having a floor panel that forms the floor surface of the vehicle, the vehicle understructure further comprising a pair of side sills extending in the longitudinal direction of the vehicle along the edges of the floor panel, a pair of rear side members that extend from the rear end of the vehicle to the front of the vehicle and are connected to the rear ends of the pair of side sills, a pair of suspension fixing parts that are connected to the pair of rear side members and to which a swingable suspension for the rear wheels is fixed, and a connecting member having X-connecting parts that extend diagonally rearward from each of the pair of side sills, intersect with each other, and are further connected to each of the pair of rear side members, the X-connecting parts of the connecting member and the pair of suspension fixing parts being adjacent to each other on the pair of rear side members, or facing each other across the pair of rear side members.

The present invention provides a vehicle underbody structure that can suppress torsional vibrations in the floor panel and improve the vehicle's noise and vibration characteristics and handling stability.

1 is a bottom view showing a vehicle underbody structure according to an embodiment of the present invention. FIG. 2 is a diagram showing a part of the vehicle undercarriage of FIG. 1 . FIG. 2 is a diagram showing another part of the vehicle underbody structure of FIG. 1 . FIG. 2 is a top view showing a part of the vehicle undercarriage of FIG. 1 . FIG. 2 is a diagram illustrating a modified example of the vehicle underbody structure of FIG. 1 . FIG. 3 is a diagram showing another modified example of the vehicle underbody structure of FIG. FIG. 2 is a diagram showing still another modified example of the vehicle underbody structure of FIG. 1 .

A typical configuration of a vehicle underbody structure according to one embodiment of the present invention is a vehicle underbody structure that includes a floor panel that forms the floor surface of the vehicle, the vehicle underbody structure further includes a pair of side sills that extend in the longitudinal direction of the vehicle along the edges of the floor panel, a pair of rear side members that extend from the rear end of the vehicle to the front of the vehicle and are connected to the rear ends of the pair of side sills, a pair of suspension fixing parts that are connected to the pair of rear side members and to which swingable suspensions for the rear wheels are fixed, and a connecting member that extends diagonally rearward from each of the pair of side sills, intersects with each other, and has X-connecting parts that are connected to each of the pair of rear side members, and the X-connecting parts of the connecting member and the pair of suspension fixing parts are adjacent to each other on the pair of rear side members, or face each other across the pair of rear side members.

In the above configuration, the suspension fixing part is connected to the rear side member. Therefore, for example, while the vehicle is traveling, the rear side member receives a load in the direction of the suspension's swing axis from the suspension via the suspension fixing part. Therefore, in the above configuration, the X-connecting part of the connecting member and the suspension fixing part are arranged adjacent to each other on the rear side member, or facing each other across the rear side member. The X-connecting part of the connecting member connects the pair of side sills and the pair of rear side members in a crosswise manner, for example along a diagonal, which increases the torsional rigidity of the floor panel.

In the above configuration, the load transmitted from the suspension fixing part to the rear side member on either the left or right side can be dispersed and released to the side sill on the opposite side via the X-connecting part of the connecting member. In addition, the load transmitted from the front member located at the front of the lower side of the floor panel to the side sill on either the left or right side, particularly the vibration in the vehicle width direction, can be dispersed and released to the rear side member on the opposite side via the X-connecting part of the connecting member. Therefore, with the above configuration, the torsional vibration of the floor panel is suppressed, and the torsional vibration of the vehicle body and the floor vibration of the floor panel caused by the vibration of the rear side member are reduced, thereby improving the noise and vibration characteristics and handling stability of the vehicle.

The X-connecting portion of the connecting member may be connected to the side surfaces of the pair of rear side members that intersect with the swing axis of the suspension.

As a result, when the pair of rear side members receive a load in the direction of the swing axis via the suspension fixing parts, the connecting member is connected to the side of the pair of rear side members that intersects with the swing axis that receives this load. Therefore, the load received by either the left or right rear side member can be efficiently received by the X-connecting part of the connecting member and dispersed to the side sill on the opposite side, allowing it to be released. As a result, vibration in the swing axis direction of the rear side members can be suppressed, and torsional vibration and floor vibration caused by this vibration can be reduced.

The X-connecting portion of the connecting member may be connected to the front end of each of the pair of side sills.

As a result, a pair of side sills and a pair of rear side members are connected, for example diagonally, by the X-shaped connecting parts of the connecting member, which further increases the torsional rigidity of the floor panel. Furthermore, torsional vibrations of the vehicle body caused by vibrations transmitted from the suspension fixing parts to the rear side members can be efficiently transmitted from the front ends of the side sills to the front member via the X-shaped connecting parts of the connecting members. This suppresses vibrations of the rear side members, thereby reducing torsional vibrations and floor vibrations caused by these vibrations.

The pair of suspension fixing parts are preferably connected to the pair of rear side members so that the swing axis direction of the suspension is parallel to the X-connection part of the connecting member.

In the above configuration, the suspension fixing part is connected to the rear side member so that the swing axis direction of the suspension is parallel to the direction in which the X-connecting part of the connecting member extends, for example the diagonal direction. This allows the vibration in the swing axis direction transmitted from the suspension fixing part to the rear side member on either the left or right side to be transmitted more efficiently to the side sill on the opposite side via the X-connecting part of the connecting member. This suppresses the vibration of the rear side member, making it possible to further reduce the torsional vibration and floor vibration caused by this vibration.

The vehicle undercarriage structure may further include one or more rear cross members extending in the vehicle width direction and connecting the pair of rear side members, and the X-connecting portion of the connecting member may be connected to the pair of rear side members and the rear cross member.

As a result, the X-connection of the connecting member is supported not only by the rear side member but also by the rear cross member, which increases the support rigidity of the connecting member and suppresses vibration of the connecting member. In addition, the load transmitted to the rear side member on either the left or right side via the suspension fixing part can be dispersed and released to the rear side member and side sill on the opposite side via the X-connection of the connecting member and the rear cross member. This suppresses vibration of the rear side member, and further reduces torsional vibration and floor vibration caused by this vibration.

The vehicle undercarriage structure may further include a front member located at the lower front portion of the floor panel, the X-connecting portions of the connecting member being connected to the inner side surfaces of each of the pair of side sills, and the connecting member may further include a pair of front connecting portions that branch off from the X-connecting portions forward of the intersection of the X-connecting portions toward the inside in the vehicle width direction and are connected to the front member.

As a result, the connecting member is connected to the side sill by the X-connection portion, and is also connected to the front member via the front connection portion. This increases the support rigidity of the connecting member, and suppresses vibration of the connecting member. In addition, vibration transmitted from the rear suspension fixing portion to the rear side member can be transmitted to the front member via the X-connection portion and front connection portion of the connecting member and dispersed. This suppresses vibration of the rear side member, and further reduces torsional vibration and floor vibration caused by this vibration.

The above-mentioned front member includes a pair of front side members located forward of the pair of side sills on the vehicle, a pair of torque boxes connecting the pair of front side members and the pair of side sills, and a connecting member connecting the pair of torque boxes, the pair of side sills and the pair of torque boxes being connected to each other at a predetermined first connecting surface, the X-connecting portion of the connecting member being connected to the first connecting surface, the pair of torque boxes and the connecting member being connected to each other at a predetermined second connecting surface, and the pair of front connecting portions being connected to the second connecting surface.

As a result, in the connecting member, the X-connection part connected to the first connecting surface and the front connecting part connected to the second connecting surface are connected via the torque box. Therefore, the connecting member can be arranged so that the X-connection part and the front connecting part are adjacent to each other, making it possible to reduce the branch angle between the X-connection part and the front connecting part. This makes it easier for vibrations transmitted from the rear side member on either the left or right side to be transmitted to the front member via the X-connection part or the front connecting part on the opposite side.

Furthermore, in the connecting member, the X-connecting portion is connected to the side sill and torque box connected at the first connecting surface, and the front connecting portion is connected to the torque box and connecting member connected at the second connecting surface. This increases the support surface of the X-connecting portion and the front connecting portion, thereby increasing the support rigidity of the connecting member and suppressing vibration of the connecting member.

The connecting member may further include a pair of intermediate connecting parts that connect the front and rear positions of the intersection of the X-connecting parts in the longitudinal direction of the vehicle.

This allows the connecting members to be connected in the fore-and-aft direction of the vehicle at positions before and after the intersection of the X-shaped connecting parts by the intermediate connecting parts. This increases the rigidity of the connecting members and suppresses vibration of the connecting members.

The front ends of the pair of intermediate connecting parts of the connecting member overlap with the rear ends of the pair of front connecting parts in the vehicle longitudinal direction via the X connecting parts, and the connecting member may further have a bridging part that is disposed inside the X connecting parts and bridges between the front ends of the pair of intermediate connecting parts and the rear ends of the pair of front connecting parts in the vehicle longitudinal direction.

As a result, the connecting member is bridged between the rear end of the front connecting part and the front end of the intermediate connecting part by a bridging part arranged inside the X connecting part, so vibration can be suppressed between the front connecting part and the intermediate connecting part. Therefore, with the above configuration, load can be efficiently transmitted in the fore-and-aft direction of the vehicle between the front member and the pair of rear side members via the front connecting part, X connecting part and intermediate connecting part of the connecting member.

The one or more rear cross members may have a first rear cross member that extends in the vehicle width direction and connects the connecting members at a position rearward of the intersection of the X-connecting parts, and the rear ends of the pair of intermediate connecting parts may be connected to the first rear cross member at a predetermined connection area and further connected to the X-connecting parts at a position adjacent to the connection area.

As a result, the X-connection of the connecting member is connected not only to the rear side members but also to the first rear cross member, which increases the support rigidity of the X-connection and suppresses vibration of the connecting member. Furthermore, when a load or vibration is transmitted from the front to the X-connection via the intermediate connecting part, the connecting member can disperse and release this load or vibration not only to the X-connection but also to the first rear cross member. Furthermore, because the intermediate connecting part and the X-connection are connected at a position adjacent to the connection area between the intermediate connecting part and the first rear cross member, the connection rigidity of the intermediate connecting part, the first rear cross member, and the X-connection can be increased.

The following describes in detail preferred embodiments of the present invention with reference to the accompanying drawings. The dimensions, materials, and other specific values shown in these embodiments are merely examples to facilitate understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements that have substantially the same functions and configurations are given the same reference numerals to avoid duplicated explanations, and elements that are not directly related to the present invention are not shown.

Figure 1 is a bottom view showing a vehicle underbody structure 100 according to an embodiment of the present invention. Figure 2 is a diagram showing a portion of the vehicle underbody structure 100 of Figure 1. The figure shows the vehicle underbody structure 100 as viewed from below the vehicle. In each of the figures below, the front-to-rear direction of the vehicle is indicated by arrows Front and Back, the left and right directions of the vehicle width are indicated by arrows Left and Right, and the top-to-bottom direction of the vehicle are indicated by arrows Up and Down.

The vehicle underbody structure 100 includes a floor panel 102 that forms the floor surface of the vehicle, a pair of side sills 104, 106, and a pair of rear side members 108, 110. As the vehicle underbody structure 100 has a symmetrical structure as shown in FIG. 1, only the structure on the right side in the vehicle width direction will be described below unless otherwise necessary.

The pair of side sills 104, 106 are spaced apart in the vehicle width direction and extend in the vehicle front-rear direction along the edges 112, 114 of the floor panel 102. The pair of rear side members 108, 110 are disposed on the inner side of the pair of side sills 104, 106 in the vehicle width direction, extend from the rear end 116 of the vehicle toward the front of the vehicle, and are connected to the rear end portions 118, 120 of the pair of side sills 104, 106.

The vehicle undercarriage 100 further includes a pair of suspension fixing parts 122, 124, a front member 126, and a connecting member 128. The pair of suspension fixing parts 122, 124 are connected to a pair of rear side members 108, 110, and a swinging suspension for the rear wheels (not shown) is fixed to them.

The suspension pivot axis Sa (see FIG. 2(a)) passes through the suspension fixing part 122. FIG. 2(a) illustrates the suspension fixing part 122 and its surrounding structure. The pivot axis Sa, which passes through the suspension fixing part 122, is inclined toward the front of the vehicle as it moves inward in the vehicle width direction, and this direction is the pivot axis direction. Therefore, the rear side member 108 connected to the suspension fixing part 122 receives a load in the pivot axis direction from the suspension via the suspension fixing part 122, for example, while the vehicle is traveling.

The front member 126 is a member located at the front of the lower side of the floor panel 102, and has a pair of front side members 130, 132, a pair of torque boxes 134, 136, and a connecting member 138. The pair of front side members 130, 132 are located further forward of the pair of side sills 104, 106 and extend in the fore-and-aft direction of the vehicle. The pair of torque boxes 134, 136 connect the pair of front side members 130, 132 to the pair of side sills 104, 106. The connecting member 138 connects the pair of torque boxes 134, 136.

The pair of side sills 104, 106 and the pair of torque boxes 134, 136 are connected to each other at predetermined first connecting surfaces 140, 142. The pair of torque boxes 134, 136 and the connecting member 138 are connected to each other at predetermined second connecting surfaces 144, 146. Note that the suspension frame 148 included in the front member 126 overlaps the second connecting surfaces 144, 146 from the underside of the vehicle as shown in the figure.

The connecting member 128 has an X-connecting portion 150, a pair of front connecting portions 152, 154, and a pair of intermediate connecting portions 156, 158. The X-connecting portions 150 extend diagonally rearward from each of the pair of side sills 104, 106 below the floor panel 102, intersect with each other at a predetermined intersection point 160, and are further connected to each of the rear side members 108, 110 on the opposite side.

The X-connection portion 150 also has a pair of side sill connection portions 162, 164 and a pair of rear connection portions 166, 168. The pair of side sill connection portions 162, 164 extend obliquely forward from the intersection point 160 toward the front end portions 170, 172 of the pair of side sills 104, 106 and the first connection surfaces 140, 142, and are connected to these front end portions 170, 172 and the first connection surfaces 140, 142.

The vehicle undercarriage 100 further includes a first rear cross member 174 and a second rear cross member 176. The first rear cross member 174 extends in the vehicle width direction and connects the front ends 178, 180 of the pair of rear side members 108, 110. The second rear cross member 176 is spaced rearward of the first rear cross member 174 as shown in the figure, extends in the vehicle width direction, and connects the pair of rear side members 108, 110.

The pair of rear connecting portions 166, 168 of the X-connection portion 150 extend obliquely rearward from the intersection point 160 toward the front ends 178, 180 of the pair of rear side members 108, 110, and are connected to these front ends 178, 180.

For this reason, in the vehicle undercarriage structure 100, the pair of side sills 104, 106 and the pair of rear side members 108, 110 are diagonally connected to the underside of the floor panel 102 by the X-connecting portion 150 of the connecting member 128. This makes it possible to further increase the torsional rigidity of the floor panel 102.

In addition, in the vehicle undercarriage structure 100, the torsional vibration of the vehicle body caused by the vibration transmitted from the suspension fixing parts 122, 124 to the rear side members 108, 110 can be efficiently transmitted from the side sills 104, 106 to the front member 126 via the X-connecting part 150 of the connecting member 128. Therefore, the vibration of the rear side members 108, 110 can be suppressed, and the torsional vibration and floor vibration caused by this vibration can be reduced.

Furthermore, the front ends 178, 180 of the pair of rear side members 108, 110 are joined to the inner sides of the rear ends 118, 120 of the pair of side sills 104, 106 located on the outer side in the vehicle width direction. Therefore, the pair of rear side members 108, 110 are sandwiched in the vehicle width direction by the pair of highly rigid side sills 104, 106. This allows the vehicle undercarriage structure 100 to more fully suppress vibration of the pair of rear side members 108, 110.

Furthermore, the pair of rear connecting portions 166, 168 of the X-connection portion 150 are also connected to the first rear cross member 174 and the second rear cross member 176 shown in FIG. 1 and to the pair of intermediate connecting portions 156, 158.

The pair of intermediate connectors 156, 158 connect the pair of side sill connectors 162, 164 and the pair of rear connectors 166, 168 in the fore-and-aft direction of the vehicle at positions before and after the intersection 160 of the X connector 150. This allows the connecting member 128 to be connected in the fore-and-aft direction of the vehicle by the intermediate connectors 156, 158 at positions before and after the intersection 160 of the X connector 150, thereby increasing rigidity and suppressing vibration.

In this way, in the vehicle undercarriage structure 100, the pair of rear connecting portions 166, 168 of the X-connecting portion 150 of the connecting member 128 are supported not only by the rear side members 108, 110 but also by the first rear cross member 174 and the second rear cross member 176. Therefore, the support rigidity of the connecting member 128 can be increased, and vibration of the connecting member 128 can be suppressed.

In addition, in the vehicle undercarriage structure 100, the load transmitted to the rear side members 108, 110 on either the left or right side via the suspension fixing parts 122, 124 can be dispersed and released to the rear side members 108, 110 and side sills 104, 106 on the opposite side via the X-connecting part 150 of the connecting member 128, the first rear cross member 174, and the second rear cross member 176. This suppresses vibration of the rear side members 108, 110, and further reduces torsional vibration and floor vibration caused by this vibration.

Furthermore, the pair of front connecting parts 152, 154 of the connecting member 128 branch off from the pair of side sill connecting parts 162, 164 forward of the intersection 160 of the X connecting part 150 toward the inside in the vehicle width direction and are connected to the second connecting surfaces 144, 146 (see FIG. 2(b)). Note that FIG. 2(b) illustrates the structure of the front connecting part 152, the side sill connecting part 162 and the surrounding area of the connecting member 128.

In the connecting member 128, as shown in FIG. 1, a pair of side sill connecting parts 162, 164 of the X-connecting part 150 connected to the first connecting surfaces 140, 142 and a pair of front connecting parts 152, 154 connected to the second connecting surfaces 144, 146 are connected via a pair of torque boxes 134, 136. As a result, the connecting member 128 can arrange the pair of side sill connecting parts 162, 164 and the pair of front connecting parts 152, 154 of the X-connecting part 150 adjacent to each other, so that the branch angle between the pair of side sill connecting parts 162, 164 and the pair of front connecting parts 152, 154 can be reduced. Therefore, vibrations transmitted from the rear side members 108, 110 on either the left or right side can be easily transmitted to the front member 126 via the side sill connecting parts 162, 164 and the front connecting parts 152, 154 on the opposite side.

In addition, in the connecting member 128, a pair of side sill connecting parts 162, 164 are connected to the pair of side sills 104, 106 and the pair of torque boxes 134, 136 connected by the first connecting surfaces 140, 142, and a pair of front connecting parts 152, 154 are connected to the pair of torque boxes 134, 136 and the connecting member 138 connected by the second connecting surfaces 144, 146. Therefore, in the vehicle undercarriage structure 100, the support surfaces of the pair of front connecting parts 152, 154 and the pair of side sill connecting parts 162, 164 of the X connecting part 150 are increased, so that the support rigidity of the connecting member 128 can be increased and vibration of the connecting member 128 can be suppressed.

Furthermore, as shown in FIG. 2(a), the X-connecting portion 150 of the connecting member 128 has a rear connecting portion 166 connected to a side surface 182 of the rear side member 108. This side surface 182 of the rear side member 108 intersects with the swing axis Sa of the suspension.

Therefore, when the rear side members 108, 110 on either the left or right side receive a load in the direction of the swing axis via the suspension fixing parts 122, 124, this load can be efficiently received by the pair of rear connecting parts 166, 168 of the X-connecting part 150 of the connecting member 128 and dispersed to the opposite side sills 104, 106 for release. As a result, the vehicle undercarriage structure 100 can suppress vibrations in the swing axis direction of the rear side members 108, 110, and reduce torsional vibrations and floor vibrations caused by these vibrations.

As shown in FIG. 2(a), in the connecting member 128, the rear connecting portion 166 of the X-connecting portion 150 extends toward a corner 184 at the connection point between the rear side member 108 and the second rear cross member 176, and is joined to overlap this corner 184. In this way, in the connecting member 128, the rear connecting portion 166 is connected to the side surface 182 of the rear side member 108 as well as to the corner 184 at the connection point between the rear side member 108 and the second rear cross member 176, improving the connection rigidity.

Furthermore, in the vehicle undercarriage structure 100, the rear connecting portion 166 of the X-connecting portion 150 and the suspension fixing portion 122 are disposed adjacent to each other on the rear side member 108 as shown in FIG. 2(a). The rear connecting portion 166 is connected to the rear side member 108 at a connection width La based on the corner portion 184, and is connected to the second rear cross member 176 at a connection width Lb. The bolt axis (not shown) of the suspension fixing portion 122 is located within the range of the connection width La of the rear side member 108.

As shown in FIG. 2(b), the side sill connection portion 162 of the X-connection portion 150 extends toward a corner 186 of the first connection surface 140 between the side sill 104 and the torque box 134, and is joined to overlap this corner 188. The side sill connection portion 162 is connected to the inner side surface 188 of the side sill 104 at a connection width Lc, and is further connected to the torque box 134 at a connection width Ld. This improves the connection rigidity of the side sill connection portion 162.

The front connecting portion 152 of the connecting member 128 extends toward a corner 190 of the second connecting surface 144 between the torque box 132 and the connecting member 138, as shown in FIG. 2(b), and is joined to overlap this corner 190. The front connecting portion 152 is connected to the torque box 134 with a connection width Le, and is further connected to the connecting member 138 with a connection width Lf. This improves the connection rigidity of the front connecting portion 152.

The front connecting part 152 is attached to the suspension frame 148 at attachment points 192. Therefore, the front connecting part 152 can receive the load transmitted from the suspension (not shown) to the suspension frame 148 via the attachment points 192 and transmit and distribute the load to the X connecting part 150. The front end part 193 of the front connecting part 152 extends linearly in the fore-and-aft direction of the vehicle as shown in FIG. 2(b), but is not limited to this and may be shaped so as to be inclined outward in the vehicle width direction as it approaches the front of the vehicle.

Figure 3 shows another part of the vehicle underbody structure 100 of Figure 1. Figure 3(a) shows the suspension fixing part 124 and its surrounding structure. Figure 3(b) shows the vehicle underbody structure 100 of Figure 3(a) with the intermediate connecting part 158 of the connecting member 128 omitted.

The rear end 194 of the intermediate connector 158 is joined to the front surface 198, the underside 200 and the rear surface 202 of the first rear cross member 174 at a predetermined connection area 196 as shown in FIG. 3(a), and is further connected to the rear connector 168 of the X connector 150 at another connection area 204 located adjacent to the connection area 196.

The vehicle lower structure 100 further includes truss structures 206, 208 shown in FIG. 3(a). The truss structure 206 is formed by being surrounded by the first rear cross member 174, the front end portion 180 of the rear side member 110, and the rear connecting portion 168, and can increase the rigidity of each of these members and the floor panel 102. The truss structure 208 is formed by being surrounded by the side sill connecting portion 164 and the rear connecting portion 168 of the X connecting portion 150, and the intermediate connecting portion 158, and can increase the rigidity of each of these members and the floor panel 102.

As shown in FIG. 3B, the rear end 210 of the rear connecting portion 168 is joined to the front surface 198, the lower surface 200, and the rear surface 202 of the first rear cross member 174 at the connection region 196. Therefore, at the connection region 196, three pieces are joined together: the rear end 194 of the intermediate connecting portion 158, the rear end 210 of the rear connecting portion 168, and the first rear cross member 174, which increases the connection rigidity of each of these members.

In this way, in the vehicle undercarriage structure 100, the rear connecting portion 168 of the X connecting portion 150 of the connecting member 128 is connected not only to the rear side member 110 but also to the first rear cross member 174, so the support rigidity of the X connecting portion 150 can be increased and vibration of the connecting member 128 can be suppressed. Furthermore, in the case where a load or vibration is transmitted from the front to the X connecting portion 150 via the intermediate connecting portion 158 of the connecting member 128, this load or vibration can be dispersed and released not only to the X connecting portion 150 but also to the first rear cross member 174.

Furthermore, the rear end 194 of the intermediate connector 158 is connected to the rear connector 168 of the X connector 150 at a position adjacent to the connection region 196 between the rear end 194 of the intermediate connector 158 and the first rear cross member 174, so the connection rigidity of the intermediate connector 158, the first rear cross member 174, and the rear connector 168 of the X connector 150 can be increased.

Figure 4 is a top view showing a portion of the vehicle underbody structure 100 of Figure 1. Figure 4(a) shows a portion of the vehicle underbody structure 100 through the floor panel 102. Figure 4(b) shows the connecting member 128 of Figure 4(a).

As shown in FIG. 4(a), the vehicle undercarriage structure 100 further includes a center tunnel 212, a front seat cross member 214, and a rear seat cross member 216. The center tunnel 212 extends in the vehicle front-rear direction at the center of the floor panel 102 in the vehicle width direction and protrudes upward.

The front seat cross member 214 is a member that extends in the vehicle width direction and connects the pair of side sills 104, 106, and has multiple front seat mounting brackets 218 installed on its upper surface. The rear seat cross member 216 is spaced from the front seat cross member 214 to the rear of the vehicle, extends in the vehicle width direction, and connects the pair of side sills 104, 106, and has multiple rear seat mounting brackets 220 installed on its upper surface.

Here, the center tunnel 212 has a tunnel section 222 that protrudes upward from the floor panel 102. For example, the tunnel section 222 protrudes less from the floor panel 102 the further toward the rear of the vehicle. For this reason, the floor panel 102 is prone to surface vibrations at a position rearward of the lower end 224 of the tunnel section 222 shown in FIG. 4(a). Therefore, in the vehicle undercarriage structure 100, the intersection point 160 of the connecting member 128 is positioned rearward of the lower end 224 of the tunnel section 222, thereby suppressing surface vibrations of the floor panel 102.

The connecting member 128 also has the rear connecting portions 166, 168 located behind the rear seat cross member 216, while overlapping the intersection 160 with the rear seat cross member 216. This allows the surface vibration of the floor panel 102 to be more sufficiently suppressed at a position rearward of the lower end 224 of the tunnel portion 222.

Furthermore, in the connecting member 128, the rear seat mounting brackets 220a, 220b installed on the rear seat cross member 216 and the side sill connecting parts 162, 164 are arranged to be stacked in the vertical direction near the intersection 160. This increases the rigidity of the underside of the front seat (not shown) that receives the load when the occupant sits down, suppressing the vibration transmitted to the occupant and improving the NV characteristics. Moreover, since the rear seat mounting brackets 220a, 220b and the side sill connecting parts 162, 164 that receive the weight of the occupant are stacked in the vertical direction near the intersection 160 of the connecting member 128, the vibration transmitted to the occupant can be more sufficiently suppressed than when the front seat mounting brackets 218 are stacked on the side sill connecting parts 162, 164.

The rear seat mounting bracket 220 may be arranged so as to overlap vertically with the intermediate connecting parts 156, 158, not limited to the side sill connecting parts 162, 164, or may be arranged so as to overlap vertically with a predetermined area 226 surrounded by the side sill connecting part 162, the intermediate connecting part 156, and the rear connecting part 166 in a plan view.

The connecting member 128 further includes a plurality of bridging portions 228a, 228b, 230a, 230b, 232a, and 232b, as shown in FIG. 4(b). The front end portion 234 of the intermediate connecting portion 156 overlaps with the rear end portion 236 of the front connecting portion 152 in the vehicle longitudinal direction via the side sill connecting portion 162 of the X connecting portion 150. The bridging portions 228a and 228b are disposed inside the side sill connecting portion 162, and function as bulkheads by bridging between the front end portion 234 of the intermediate connecting portion 156 and the rear end portion 236 of the front connecting portion 152 in the vehicle longitudinal direction. This increases the rigidity between the front connecting portion 152 and the intermediate connecting portion 156 while improving the efficiency of vibration and load transmission.

The front end 238 of the intermediate connection part 158 overlaps with the rear end 240 of the front connection part 154 in the vehicle longitudinal direction via the side sill connection part 164 of the X connection part 150. The bridging parts 230a, 230b are disposed inside the side sill connection part 164 and function as bulkheads by bridging between the front end 238 of the intermediate connection part 158 and the rear end 240 of the front connection part 154 in the vehicle longitudinal direction. This increases the rigidity between the front connection part 154 and the intermediate connection part 158 while improving the efficiency of vibration and load transmission.

The front end 242 of the rear connecting part 168 overlaps with the rear end 244 of the side sill connecting part 162 in the vehicle longitudinal direction via the intersection 160 of the X connecting part 150. The bridging parts 232a, 232b are disposed inside the intersection 160 of the X connecting part 150, and function as bulkheads by bridging between the front end 242 of the rear connecting part 168 and the rear end 244 of the side sill connecting part 162 in the vehicle longitudinal direction. This increases the rigidity between the rear connecting part 168 and the side sill connecting part 162 while improving the efficiency of vibration and load transmission.

Therefore, in the vehicle undercarriage structure 100, loads can be efficiently transmitted in the fore-and-aft direction between the front member 126 and the pair of rear side members 108, 110 via the front connecting parts 152, 154, the X connecting part 150, and the intermediate connecting parts 156, 158 of the connecting member 128.

Although the connecting member 128 and rear side members 108, 110 are arranged below the floor panel 102, this is not limiting and they may be arranged above the floor panel 102.

Figure 5 is a schematic diagram showing a modified example of the vehicle underbody structure 100 of Figure 1. In the vehicle underbody structure 100A shown in Figure 5 (a), the rear connecting portion 166 of the X connecting portion 150 of the connecting member 128 and the suspension fixing portion 122 are connected to the regions of the rear side member 108 that face each other in the vehicle width direction, i.e., the side surfaces 246 and 248. In other words, the rear connecting portion 166 of the X connecting portion 150 and the suspension fixing portion 122 are arranged to face each other across the rear side member 108. Even with this vehicle underbody structure 100A, it is possible to suppress vibration in the axial direction of the swing axis Sa of the rear side member 108.

The vehicle underbody structure 100B shown in FIG. 5(b) connects the rear connecting portion 166 of the X connecting portion 150 of the connecting member 128 and the suspension fixing portion 122 to the areas of the rear side member 108 that face each other in the vertical direction, i.e., the upper surface 250 and the lower surface 252. In other words, the rear connecting portion 166 of the X connecting portion 150 and the suspension fixing portion 122 are arranged adjacent to each other on the rear side member 108. Even with this vehicle underbody structure 100B, it is possible to suppress vibration in the axial direction of the swing axis Sa of the rear side member 108.

Figure 6 shows another modified example of the vehicle underbody structure 100 in Figure 2(a). The modified vehicle underbody structure 100C differs from the vehicle underbody structure 100 in that it includes a suspension fixing part 122A instead of the suspension fixing part 120.

The suspension fixing part 122A is connected to the rear side member 108 so that the oscillating axis direction of the suspension oscillating shaft Sb (not shown) is parallel to the extending direction of the rear connecting part 166 of the X connecting part 150 of the connecting member 128, for example, the diagonal direction T.

In this manner, in the vehicle lower structure 100C, the suspension fixing part 122A is connected to the rear side member 108 so that the sway axis direction of the suspension sway axis Sb is parallel to the diagonal direction T of the rear connecting part 166 of the X connecting part 150. Although not shown, in the vehicle lower structure 100C, the suspension fixing part 124 is also connected to the rear side member 110 so that it is parallel to the diagonal direction of the rear connecting part 168.

Therefore, in the vehicle lower structure 100C, the vibration in the direction of the swing axis transmitted from the suspension fixing parts 122A, 124 to the rear side members 108, 110 on either the left or right side can be transmitted more efficiently to the side sills 104, 106 on the opposite side via the X-connecting part 150 of the connecting member 128. This suppresses the vibration of the rear side members 108, 110, and further reduces the torsional vibration and floor vibration caused by this vibration.

Figure 7 shows yet another modified example of the vehicle underbody structure 100 of Figure 1. The vehicle underbody structure 100D shown in Figure 7(a) differs from the vehicle underbody structure 100 in that it includes a connecting member 128A instead of the connecting member 128.

The connecting member 128A has an X-connecting portion 150A, a pair of front connecting portions 162A, 164A, and a pair of intermediate connecting portions 156A, 158A. The X-connecting portion 150A has a pair of side sill connecting portions 162A, 164A and a pair of rear connecting portions 166A, 168A. The X-connecting portion 150A connects the pair of side sills 104, 106 and the pair of rear side members 108, 110 so as to cross each other below the floor panel 102, but does not connect them along a diagonal line as shown in FIG. 7(a).

That is, the pair of side sill connecting parts 162A, 164A extend obliquely forward from the intersection point 160A not toward the above-mentioned first connecting surfaces 140, 142, but toward predetermined points 254, 256 of the pair of side sills 104, 106 located rearward of the first connecting surfaces 140, 142, and are connected to these predetermined points 254, 256.

In addition, the pair of rear connecting portions 166A, 168A extend obliquely rearward from the intersection point 160A toward the front ends 178, 180 of the pair of rear side members 108, 110 and are connected to these front ends 178, 180.

The pair of front connecting parts 152A, 154A branch off from the pair of side sill connecting parts 162A, 164A forward of the intersection point 160A of the X connecting part 150A toward the inside in the vehicle width direction and are connected to the front member 126. The pair of intermediate connecting parts 156A, 158A connect the pair of side sill connecting parts 162A, 164A and the pair of rear connecting parts 166A, 168A in the front-rear direction of the vehicle at positions in front of and behind the intersection point 160A.

In this way, the vehicle undercarriage structure 100C does not connect the pair of side sills 104, 106 and the pair of rear side members 108, 110 along a diagonal line on the underside of the floor panel 102 by the X-connecting portion 150A of the connecting member 128A, but does connect them crosswise, thereby increasing the torsional rigidity of the floor panel 102.

The vehicle underbody structure 100E shown in FIG. 7(b) differs from the vehicle underbody structure 100 in that it includes a connecting member 128B instead of the connecting member 128. The connecting member 128B includes a pair of floor side members 258, 260, an X member 262, and a pair of side sill connecting portions 162B, 164B.

As shown in FIG. 7(b), the pair of floor side members 258, 260 have front ends 264, 266 connected to the front member 126 below the floor panel 102, and rear ends 268, 270 connected to the front ends 178, 180 of the pair of rear side members 108, 110. In this way, the pair of floor side members 258, 260 connect the front member 126 to the pair of rear side members 108, 110.

The X-member 262 is placed in an X-shape between the pair of floor side members 258, 260 and is connected to each of the pair of floor side members 258, 260. The pair of side sill connecting portions 162B, 164B branch out from the pair of floor side members 258, 260 to the outside in the vehicle width direction and are connected to the first connecting surfaces 140, 142.

The connecting member 128B further includes multiple bridging portions 272a, 272b, 274a, 274b, 276, and 278, as shown in FIG. 7B. The front end portion 280 of the X-member 262 overlaps with the rear end portion 282 of the side sill connecting portion 162B in the extension direction of the X-member 262 via the floor side member 258. The bridging portions 272a and 272b are disposed inside the floor side member 258 and function as bulkheads by bridging between the front end portion 280 of the X-member 262 and the rear end portion 282 of the side sill connecting portion 162B in the extension direction. This increases the rigidity between the X-member 262 and the side sill connecting portion 162B while improving the transmission efficiency of vibrations and loads.

The front end 284 of the X-member 262 overlaps with the rear end 286 of the side sill connection part 164B in the extension direction of the X-member 262 via the floor side member 260. The bridging parts 274a and 274b are disposed inside the floor side member 260 and function as bulkheads by bridging between the front end 284 of the X-member 262 and the rear end 286 of the side sill connection part 164B in the extension direction. This increases the rigidity between the X-member 262 and the side sill connection part 164B while improving the efficiency of vibration and load transmission.

The rear end 288 of the X-member 262 overlaps with the rear end 268 of the floor side member 258 in the extension direction of the X-member 262. The bridging portion 276 is disposed inside the floor side member 258 and functions as a bulkhead by bridging between the rear end 288 of the X-member 262 and the rear end 268 of the floor side member 258 in the extension direction. This increases the rigidity between the X-member 262 and the floor side member 258 while improving the efficiency of vibration and load transmission.

The rear end 290 of the X-member 262 overlaps with the rear end 270 of the floor side member 260 in the extension direction of the X-member 262. The bridging portion 278 is disposed inside the floor side member 260 and functions as a bulkhead by bridging between the rear end 290 of the X-member 262 and the rear end 270 of the floor side member 260 in the extension direction. This increases the rigidity between the X-member 262 and the floor side member 260 while improving the efficiency of vibration and load transmission.

Therefore, in the vehicle substructure 100E, the load can be efficiently transmitted in the vehicle longitudinal direction between the front member 126 and the pair of rear side members 108, 110 via the pair of floor side members 258, 260 of the connecting member 128B, the pair of side sill connecting portions 162B, 164B, and the X member 262. Although the connecting member 128B differs in the number and shape of each component from the connecting member 128 shown in FIG. 1, the shape is the same when the components are combined, and therefore the connecting member 128B has the same function, such as transmitting and dispersing loads and vibrations. Although the pair of floor side members 258, 260 are arranged below the floor panel 102, this is not limiting and they may be arranged above the floor panel 102.

As described above, in the vehicle undercarriage structures 100, 100A to 100E, the torsional rigidity of the floor panel 102 can be increased by the connecting members 128, 128A, 128B. In addition, in the vehicle undercarriage structures 100, 100A to 100E, the load transmitted to the rear side members 108, 110 on either the left or right side via the connecting members 128, 128A, 128B can be dispersed and released to the side sills 104, 106 on the opposite side, and the load transmitted from the front member 126 to the side sills 104, 106 on either the left or right side can be dispersed and released to the rear side members 108, 110 on the opposite side.

Therefore, the vehicle substructures 100, 100A-100E suppress the torsional vibration of the floor panel 102, thereby reducing the torsional vibration of the vehicle body and the floor vibration of the floor panel 102 caused by the vibration of the rear side members 108, 110, thereby improving the NV characteristics and handling stability of the vehicle.

The above describes preferred embodiments of the present invention with reference to the attached drawings, but it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

The present invention can be used in vehicle undercarriage structures.

100, 100A-100E...vehicle underbody structure, 102...floor panel, 104, 106...side sill, 108, 110...rear side member, 112, 114...edge of floor panel, 116...rear end of vehicle, 118, 120...rear end of side sill, 122, 122A, 124...suspension fixing part, 126...front member, 128, 128A, 128B...connecting member, 130, 132...front side member, 134, 136...torque box, 138...connecting member, 140, 142...first connecting surface, 144, 146...second connecting surface, 148...suspension frame, 150, 150A...X connecting part , 152, 152A, 154, 154A...front connection portion, 156, 156A, 158, 158A...middle connection portion, 160, 160A...intersection portion, 162, 162A, 162B, 164, 164A, 164B...side sill connection portion, 166, 166A, 168, 168A...rear connection portion, 170, 172...front end portion of side sill, 174...first rear cross member, 176...second rear cross member, 178, 180...front end portion of rear side member, 182, 246, 248...side surface of rear side member, 184, 186, 190...corner portion, 188...inner side surface of side sill, 192...mounting point, 193...front connection portion front end of connecting portion, 194...rear end of intermediate connecting portion, 196, 204...connection area, 198...front surface of first rear cross member, 200...lower surface of first rear cross member, 202...rear surface of first rear cross member, 206, 208...truss structure, 210...rear end of rear connecting portion, 212...center tunnel, 214...front seat cross member, 216...rear seat cross member, 218...front seat mounting bracket, 220, 220a, 220b...rear seat mounting bracket, 222...tunnel portion, 224...lower end of tunnel portion, 226...predetermined area, 228a, 228b, 230a, 230b, 232a, 232b , 272a, 272b, 274a, 274b, 276, 278...bridge portion, 234, 238...front end of intermediate connection portion, 236, 240...rear end of front connection portion, 242...front end of rear connection portion, 244, 282, 286...rear end of side sill connection portion, 250...upper surface of rear side member, 252...lower surface of rear side member, 254, 256...predetermined portion of side sill, 258, 260...floor side member, 262...X member, 264, 266...front end of floor side member, 268, 270...rear end of floor side member, 280, 284...front end of X member, 288, 290...rear end of X member

Claims (10)

In a vehicle underbody structure including a floor panel that forms a floor surface of a vehicle, the vehicle underbody structure further includes:
A pair of side sills extending in a front-rear direction of the vehicle along edges of the floor panel;
a pair of rear side members extending from a rear end of the vehicle toward a front side of the vehicle and connected to rear ends of the pair of side sills;
a pair of suspension fixing portions connected to the pair of rear side members and to which a swingable suspension for a rear wheel is fixed;
a connecting member having an X-shaped connecting portion extending obliquely rearward from each of the pair of side sills, intersecting each other, and further connected to each of the pair of rear side members,
the X-connecting portion of the connecting member and the pair of suspension fixing portions are adjacent to each other on the pair of rear side members, or face each other across the pair of rear side members. 2. The vehicle underbody structure according to claim 1, wherein the X-connecting portion of the connecting member is connected to a side surface of the pair of rear side members that intersects with a swing axis of the suspension that is a rotation axis of the suspension fixing portion relative to the rear wheels and passes through the suspension fixing portion . The vehicle underbody structure according to claim 1 or 2, characterized in that the X-connecting portion of the connecting member is connected to the front end portion of each of the pair of side sills. The vehicle underbody structure according to claim 3, characterized in that the pair of suspension fixing parts are connected to the pair of rear side members so that the swing axis direction of the suspension is parallel to the X-connection part of the connecting member. The vehicle underbody structure further includes one or more rear cross members extending in a vehicle width direction and connecting the pair of rear side members,
5. The vehicle underbody structure according to claim 1, wherein the X-connecting portion of the connecting member is connected to the pair of rear side members and the rear cross member. The vehicle undercarriage further comprises:
a front member located at a lower front portion of the floor panel,
The X-connecting portions of the connecting member are connected to the inner side surfaces of the pair of side sills,
6. The vehicle underbody structure according to claim 5, wherein the connecting member further includes a pair of front connecting portions branching off from the X connecting portions forward of an intersection of the X connecting portions toward the inside in the vehicle width direction and connected to the front member. The front member is
A pair of front side members located forward of the pair of side sills;
a pair of torque boxes connecting the pair of front side members and the pair of side sills;
a connecting member connecting the pair of torque boxes,
the pair of side sills and the pair of torque boxes are connected to each other at a predetermined first connection surface,
The X-connecting portion of the connecting member is connected to the first connecting surface,
The pair of torque boxes and the connecting member are connected to each other at a predetermined second connecting surface,
The vehicle underbody structure according to claim 6, wherein the pair of front connecting portions are connected to the second connecting surface. The vehicle undercarriage structure according to claim 6 or 7, characterized in that the connecting member further has a pair of intermediate connecting parts that connect the front and rear positions of the intersection of the X-connecting parts in the longitudinal direction of the vehicle. front end portions of the pair of intermediate connecting portions of the connecting member overlap with rear end portions of the pair of front connecting portions in the vehicle front-rear direction via the X connecting portions,
9. The vehicle underbody structure according to claim 8, wherein the connecting member further includes a bridging portion disposed inside the X-shaped connecting portion and bridging between front ends of the pair of intermediate connecting portions and rear ends of the pair of front connecting portions in the vehicle longitudinal direction. the one or more rear cross members include a first rear cross member extending in a vehicle width direction and connecting positions rearward of intersections of the X connection portions of the connecting members,
10. The vehicle underbody structure according to claim 8, wherein rear ends of the pair of intermediate connectors are connected to the first rear cross member at predetermined connection regions, and are further connected to the X connector at a position adjacent to the connection region.

Images