Vehicle lower part structure

Abstract

To provide a vehicle lower part structure capable of stabilizing a folding mode of a suspension member at the time of vehicle collision.SOLUTION: A front side mount part 28 that supports a front part of a motor unit 26 is provided in a front side of the motor unit 26 mounted in a suspension member 14 in a vehicle lower side than the center of gravity G of the motor unit 26. Rear side mount parts 32 that support a rear part of the motor unit 26 are provided in a rear side of the motor unit 26 in an opposite side from the front side mount part 28 and in right and left of an upper side with the center of gravity G of the motor unit 26 therebetween. As a result, when an impact load F is transmitted to the motor unit 26, a moment M to the vehicle lower side and vehicle rear side having the center of gravity G as a center is applied to the motor unit 26, and the suspension member 14 can be stably folded so as to project downward.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercarriage. [Background technology]

[0002] Patent Document 1 discloses a technology that includes a motor compartment cross member (hereinafter referred to as "MC cross member") that is rectangular in plan view and supports a drive motor. In this prior art, a part of the end of the MC cross member is weaker in strength than other parts, and a front side member that is folded toward the inside of the vehicle width direction is inserted into the weak part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-083144 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, when the drive motor is supported by a suspension member, it is difficult to stably bend the suspension member toward the bottom of the vehicle, in other words, to bend it downward in a convex manner, in the event of a frontal collision of the vehicle (hereinafter referred to as a "frontal collision of the vehicle") or a rearward collision of the vehicle (hereinafter referred to as a "rearward collision of the vehicle").

[0005] SUMMARY OF THE INVENTION In consideration of the above, an object of the present invention is to provide a vehicle underbody structure that can stabilize the folding mode of a suspension member in the event of a vehicle collision. [Means for solving the problem]

[0006] The vehicle undercarriage structure of claim 1 is provided on a cross member that forms the front side of a suspension member and extends in the vehicle width direction, and is equipped with a front mount portion that is positioned below the center of gravity of a motor unit that drives the vehicle and supports the front of the motor unit, and a rear mount portion that is positioned on the opposite side of the front mount portion and above the vehicle with the center of gravity of the motor unit between them, and supports the rear of the motor unit.

[0007] The vehicle undercarriage structure according to claim 1 includes a front mount that supports the front portion of the motor unit and a rear mount that supports the rear portion of the motor unit. The front mount is provided on a cross member that forms the front side of the suspension member and extends in the vehicle width direction, and is located below the center of gravity of the motor unit that drives the vehicle. Meanwhile, the rear mount is located on the opposite side of the front mount and above the vehicle, with the center of gravity of the motor unit between them, and supports the rear portion of the motor unit.

[0008] In the present invention, when an impact load is input to the suspension member during a frontal collision of the vehicle, the impact load is transmitted to the motor unit side via the front mount portion. The front mount portion is located below the center of gravity of the motor unit, and the rear mount portion is located on the opposite side of the front mount portion and above the center of gravity of the motor unit.

[0009] Therefore, in the present invention, when an impact load is transmitted to the motor unit, a moment acts on the motor unit about the center of gravity toward the lower and rearward sides of the vehicle, causing the motor unit to rotate toward the lower and rearward sides of the vehicle, which can cause the suspension member to bend downwardly toward the lower side of the vehicle.

[0010] In other words, in the present invention, the force of the motor unit attempting to rotate toward the lower and rearward side of the vehicle is utilized to promote downward convex bending of the suspension member, making it possible to stably cause the suspension member to bend downward convexly.

[0011] In other words, the present invention makes it possible to control the folding mode of the suspension member. As a result, the present invention makes it possible to eliminate extra reinforcing members, etc., that are used to control the folding mode of the suspension member, thereby enabling the weight of the suspension member to be reduced.

[0012] The vehicle undercarriage structure of claim 2 is the vehicle undercarriage structure of claim 1, wherein the motor unit is disposed at the front of the vehicle, the front mounting portion is provided at one location approximately in the center of the vehicle width direction, and the rear mounting portion is provided on the left and right sides of the vehicle width direction.

[0013] In the vehicle undercarriage structure according to claim 2, the motor unit is disposed at the front of the vehicle. The front mount portion is provided at one location in the approximate center of the vehicle width direction, and the rear mount portions are provided on the left and right sides of the vehicle width direction.

[0014] In a comparative example, if the front mounts were provided on the left and right sides of the vehicle width direction, the impact load transmitted to the front mounts would be dispersed during a vehicle collision. In contrast, in the present invention, the front mounts are provided in one location approximately in the center of the vehicle width direction, so the impact load transmitted to the front mounts can be concentrated in one location, making it possible to apply a moment to the motor unit more effectively than in the comparative example.

[0015] A vehicle underbody structure according to a third aspect of the present invention is the vehicle underbody structure according to the second aspect, wherein the rear mount portion is supported by a cast member integrally formed by die-casting.

[0016] In the vehicle undercarriage structure according to claim 3, the rear mount portion is supported by a cast member integrally formed by die-casting. Therefore, in the present invention, a cross member for providing the rear mount portion is not required in the suspension member, thereby enabling weight reduction.

[0017] Here, die casting has high strength. Therefore, in the present invention, the rear mount portion is supported by a cast member integrally formed by die casting, which allows a moment to be stably applied to the motor unit downward and rearward of the vehicle, centered on the rear mount portion. Therefore, in the event of a vehicle collision, the present invention further promotes downward convex bending of the suspension member, making it possible to more stably cause the suspension member to bend downward convexly.

[0018] The vehicle undercarriage structure of claim 4 is the vehicle undercarriage structure of claim 1, wherein a first bent portion is provided at the lower part of the side rail that forms part of the suspension member and extends in the fore-and-aft direction of the vehicle, on the front side of the front mount portion in a side view of the vehicle, and which serves as a starting point for bending the side rail when the vehicle is hit.

[0019] In the vehicle undercarriage structure according to claim 4, a first bent portion is provided at the lower portion of a side rail that forms part of a suspension member and extends in the vehicle longitudinal direction, on the vehicle front side of the front mount portion in a side view of the vehicle. This first bent portion is the starting point for bending of the side rail in the event of a vehicle collision, but because the first bent portion is provided at the lower portion of the side rail, the side rail bends upward on the vehicle at the first bent portion, resulting in a so-called upward convex bend.

[0020] In the event of a vehicle collision, the force exerted by the motor unit to rotate the suspension member downward and toward the rear of the vehicle causes the suspension member to bend downward between the front and rear mount portions toward the bottom of the vehicle (bottom bent portion).

[0021] In the present invention, by forming an upward convex bending mode on the front side of the downward convex bending portion, it is possible to prevent the suspension member from bending along the vehicle width direction, and to allow the suspension member to bend stably along the vehicle up-down direction.

[0022] The vehicle undercarriage structure of claim 5 is the vehicle undercarriage structure of claim 1, wherein a second bend portion is provided at the lower part of the side rail that forms part of the suspension member and extends in the fore-and-aft direction of the vehicle, on the rear side of the rear mount portion in a side view of the vehicle, and which serves as a starting point for bending the side rail when the vehicle is hit.

[0023] In the vehicle undercarriage structure according to claim 5, a second bent portion is provided at the lower portion of a side rail that forms part of a suspension member and extends in the vehicle longitudinal direction, on the vehicle rear side of the rear mount portion in a side view of the vehicle. This second bent portion is the starting point for bending of the side rail when the vehicle is hit, but because the second bent portion is provided at the lower portion of the side rail, the side rail bends upward in a convex manner at the second bent portion.

[0024] In the event of a vehicle collision, when the suspension member bends downwardly (at the downward bent portion) between the front mount portion and the rear mount portion toward the bottom of the vehicle, the present invention forms an upward convex bend mode on the rear side of the downward bent portion. This prevents the suspension member from bending along the vehicle width direction during a vehicle collision, and enables the suspension member to bend stably along the vehicle up-down direction. [Effects of the Invention]

[0025] As described above, the vehicle underbody structure according to the present invention can stabilize the folding mode of the suspension member in the event of a vehicle collision. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic perspective view of a suspension member and a motor unit that are part of a vehicle undercarriage according to an embodiment, as viewed obliquely from the front and above. FIG. [Figure 2A] FIG. 10 is a schematic plan view illustrating a comparative example and a problem with a suspension member. [Figure 2B] FIG. 4 is a schematic side view for explaining a deformation mode of a suspension member. [Figure 3A] 1 is a schematic side view showing a state immediately before deformation of a suspension member that is part of a vehicle undercarriage structure according to an embodiment. [Figure 3B] 1 is a schematic side view showing a state in which a suspension member, which is part of a vehicle undercarriage structure according to an embodiment, is deformed. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, a vehicle undercarriage structure according to an embodiment will be described with reference to the drawings. Note that the arrow FR shown as appropriate in each drawing indicates the front direction of the vehicle, the arrow UP indicates the upward direction of the vehicle, and the arrow RH indicates the right side of the vehicle. Hereinafter, when the front-rear, left-right, top-bottom directions are used in the description, they refer to the front and rear in the front-rear direction of the vehicle, the left and right in the width direction of the vehicle, and the top and bottom in the top-bottom direction of the vehicle, unless otherwise specified.

[0028] <Vehicle undercarriage configuration> First, the configuration of the vehicle underbody structure according to this embodiment will be described.

[0029] 1 and 3A show a suspension member 14 provided in a front portion 12 of a vehicle 10 to which the vehicle undercarriage structure according to this embodiment is applied. This suspension member 14 is fastened to a pair of left and right front side members (not shown) that extend in the front-to-rear direction of the vehicle in the front portion 12 of the vehicle 10. A pair of left and right wheel houses (not shown) in which wheels 16 are arranged are provided on both outer sides of the pair of left and right front side members in the vehicle width direction.

[0030] For example, in this embodiment, the pair of left and right front side members and the pair of left and right wheel housings are connected by a cross member (not shown) that extends in the vehicle width direction, and the pair of left and right front side members, the pair of left and right wheel housings, and the cross member are integrally formed by die-casting using an aluminum alloy, a magnesium alloy, or the like.

[0031] In this embodiment, as shown in FIG. 1, the suspension member 14 includes a pair of left and right side rails 18 extending in the fore-and-aft direction of the vehicle at both ends in the vehicle width direction, and a cross member 20 extending in the vehicle width direction at the front 12 of the vehicle 10 and connecting the pair of left and right side rails 18.

[0032] The left and right side rails 18 are provided with connecting portions 22, 24 at both ends in the extension direction, and can be connected to the left and right front side members, respectively, via mounts (not shown) that include shock-absorbing materials such as vibration-isolating rubber. With the left and right side rails 18 connected to the left and right front side members, respectively, the suspension member 14 is disposed below the left and right front side members.

[0033] A motor unit 26 can be mounted on the suspension member 14, and the motor unit 26 is disposed between the left and right side rails 18 and between the left and right front side members.

[0034] 1 and 3A, a front mount portion 28 is provided on the front side of the motor unit 26. The front mount portion 28 is located below the center of gravity G of the motor unit 26 and is located in one location in the approximate center of the motor unit 26 in the vehicle width direction, and is configured to include a buffer member.

[0035] In this embodiment, the front mount portion 28 can be connected to the rear of the cross member 20 of the suspension member 14. A pair of left and right stays 30 are provided on the rear of the cross member 20, and the front mount portion 28 is connected via the stays 30. The front of the motor unit 26 is supported by the front mount portion 28.

[0036] Meanwhile, rear mount portions 32 are provided on the rear side of the motor unit 26. The rear mount portions 32 are arranged on the opposite side and above the front mount portion 28 across the center of gravity G of the motor unit 26, and are arranged on the left and right sides of the motor unit 26 on both outer sides in the vehicle width direction, and are configured to include cushioning members.

[0037] In this embodiment, the left and right rear mounts 32 are coupled to respective coupling portions provided on the left and right sides of the die-cast body, although these are not shown. The rear of the motor unit 26 is supported by these left and right rear mounts 32.

[0038] 1 and 2B, the left and right side rails 18 are provided at their lower portions with bent portions (first bent portions) 34 near the cross member 20, and bent portions (second bent portions) 36 forward of the joint portion 24. Although not shown, notches are formed in the bent portions 34 and 36, and serve as starting points for bending the side rails 18 in the event of a frontal collision of the vehicle 10 (see FIG. 3B).

[0039] Furthermore, the side rail 18 is provided with a horizontal portion 40 further forward of the bent portion 34, and a horizontal portion 42 further rearward of the bent portion 36. The horizontal portion 40 and the horizontal portion 42 are formed along a substantially horizontal direction, with the horizontal portion 42 being positioned below the horizontal portion 40. A convex portion 44 is provided between the horizontal portion 40 and the horizontal portion 42, and is formed in a convex shape toward the lower side of the vehicle.

[0040] <Actions and effects of vehicle undercarriage structures> First, the operation and effects of the vehicle underbody structure according to this embodiment will be described.

[0041] In this embodiment, as shown in Figures 1 and 3A, a front mount portion 28 is provided on the front side of the motor unit 26 mounted on the suspension member 14, supporting the front portion of the motor unit 26 below the center of gravity G of the motor unit 26.

[0042] In addition, rear mount portions 32 that support the rear portion of the motor unit 26 are provided on the left and right sides of the motor unit 26 on the opposite side and above the front mount portion 28, with the center of gravity G of the motor unit 26 between them.

[0043] In this embodiment, for example, when an impact load is input to the suspension member 14 during a frontal collision of the vehicle 10, the impact load F is transmitted to the motor unit 26 side via the front mount portion 28. Note that the term "frontal collision" here is a concept that includes not only a full-overlap frontal collision (head-on collision), but also an offset collision, an oblique collision, and a small-overlap collision.

[0044] As described above, the front mount portion 28 is disposed below the center of gravity G of the motor unit 26 in the vehicle, and the rear mount portion 32 is disposed above the center of gravity G of the motor unit 26 in the vehicle.

[0045] Therefore, when an impact load F is transmitted to the motor unit 26, a moment M acts on the motor unit 26 toward the lower and rearward side of the vehicle, centered on the center of gravity G. As a result, in this embodiment, as shown in Fig. 3B, the motor unit 26 rotates toward the lower and rearward side of the vehicle, and as a result, the side rail 18 of the suspension member 14 can bend downwardly toward the lower side of the vehicle (downwardly convex bent portion 38).

[0046] In other words, in this embodiment, the force of the motor unit 26 attempting to rotate toward the lower and rearward side of the vehicle is utilized to encourage the downward convex bending of the side rail 18 of the suspension member 14, making it possible to stably cause the side rail 18 to bend downward convexly.

[0047] In this way, in this embodiment, it is possible to stabilize the folding mode of the suspension member 14 during a frontal collision of the vehicle 10. That is, in this embodiment, it is possible to control the folding mode of the suspension member 14, and as a result, it is possible to eliminate extra reinforcing members and the like for controlling the folding mode of the suspension member 14, and it is possible to reduce the weight of the suspension member 14.

[0048] In this embodiment, as shown in FIG. 1, the front mount portion 28 is provided in one location substantially in the center in the vehicle width direction, and the rear mount portions 32 are provided on the left and right sides in the vehicle width direction.

[0049] For example, as a comparative example (not shown), if the front mount portion 28 is provided on the left and right sides of the vehicle width direction, when the vehicle 10 collides, the impact load F (see Figure 3A) transmitted to the front mount portion 28 side will be dispersed.

[0050] In contrast, in this embodiment, the front mount portion 28 is provided in one location, approximately in the center of the vehicle width direction, so that the impact load F transmitted to the front mount portion 28 can be concentrated in one location, making it possible to apply a moment to the motor unit 26 more effectively than in the comparative example.

[0051] Furthermore, in this embodiment, the rear mount portion 32 is supported by a cast member that is integrally molded by die casting. Therefore, in this embodiment, the suspension member 14 does not need a cross member for providing the rear mount portion 32, which makes it possible to reduce the weight accordingly.

[0052] Here, die casting has high strength, so in this embodiment, rear mount portion 32 is supported by a cast member integrally formed by die casting, which allows moment M' to be applied stably to motor unit 26 downward and rearward of the vehicle, with rear mount portion 32 as the center.

[0053] Therefore, in this embodiment, when the vehicle 10 collides, downward convex bending of the suspension member 14 relative to the side rail 18 is further promoted, and the suspension member 14 can be more stably bent downward convexly.

[0054] In this embodiment, a bent portion 34 is provided near the cross member 20 at the bottom of each of the left and right side rails 18 of the suspension member 14, and a bent portion 36 is provided forward of the connecting portion 24 (see FIG. 1). Although not shown, the bent portions 34, 36 may have a notch formed therein, which serves as a starting point for bending the side rails 18 when an impact load is applied.

[0055] Since the bent portions 34, 36 are provided at the bottom of the side rail 18, when the vehicle is hit, the side rail 18 bends at the bent portion 34 toward the upper side of the vehicle, forming an upward convex bend.

[0056] When the vehicle 10 collides, the force of the motor unit 26 to rotate the suspension member 14 toward the vehicle lower side and rear side causes the suspension member 14 to bend downward at a downward convex bending part 38 toward the vehicle lower side between the front mount part 28 and the rear mount part 32.

[0057] In this embodiment, by forming an upward convex bending mode on the front side of the downward convex bending portion 38, it is possible to prevent the suspension member 14 from bending along the vehicle width direction, as shown in FIG. 2A, and to bend the suspension member 14 along the vehicle up-down direction, as shown in FIG. 2B.

[0058] 3A and 3B, at bent portion 36, similar to bent portion 34, side rail 18 of suspension member 14 is bent toward the upper side of the vehicle, forming an upward convex bend.

[0059] Therefore, in this embodiment, as a comparative example, as shown in FIG. 2A, the side rails 18 of the suspension member 14 are prevented from bending along the vehicle width direction, and as shown in FIGS. 3A and 3B, the suspension member 14 can be bent along the vehicle up-down direction.

[0060] Furthermore, in this embodiment, the side rail 18 of the suspension member 14 is provided with a horizontal portion 40 located further forward of the bent portion 34. The horizontal portion 40 is formed in a substantially horizontal direction, and when an impact load F is transmitted to the horizontal portion 40 during a frontal collision of the vehicle 10, the horizontal portion 40 attempts to move toward the rear of the vehicle.

[0061] In this way, because the direction in which the impact load F is transmitted and the direction in which the horizontal portion 40 is formed are substantially the same, the impact load F transmitted toward the bent portion 34 is larger than, for example, when the side rail 18 is provided with an inclined portion that is inclined in the vehicle vertical direction further forward than the bent portion 34 (not shown). Therefore, in this embodiment, it is possible to make it easier for bending to occur starting from the bent portion 34.

[0062] In this embodiment, the side rail 18 of the suspension member 14 is provided with a horizontal portion 42 located rearward of the bent portion 36. The horizontal portion 42 is formed in a substantially horizontal direction. Furthermore, the side rail 18 is provided with a convex portion 44 between the horizontal portion 40 and the horizontal portion 42, the convex portion 44 being formed in a convex shape toward the lower side of the vehicle.

[0063] In this way, by providing the convex portion 44 on the side rail 18, when the vehicle 10 collides and an impact load F is transmitted to the side rail 18, the convex portion 44 becomes more likely to deform downward toward the vehicle and bend downward.

[0064] Here, the horizontal portion 42 tends to move relatively toward the front of the vehicle due to deformation of the side rail 18. Because the horizontal portions 40 and 42 are formed along the vehicle longitudinal direction, in this embodiment, they move closer to each other more effectively than if, for example, they were inclined portions inclined in the vehicle vertical direction.

[0065] Therefore, in this embodiment, it is possible to more effectively facilitate downward convex folding of the side rail 18. At this time, it is also possible to facilitate folding of the side rail 18 starting from the bent portion 36.

[0066] <Supplementary explanation of the above embodiment> In this embodiment, a suspension member 14 provided at the front 12 of the vehicle 10 has been described, but it goes without saying that the present invention may also be applied to a suspension member provided at the rear of the vehicle 10.

[0067] In addition, in this embodiment, the rear mounting portion 32 is supported by a cast member integrally molded by die-casting, but this is not limited to this, as long as it is positioned on the opposite side of the front mounting portion 28 and above the vehicle, with the center of gravity G of the motor unit 26 between them.

[0068] For example, in this embodiment, the front side member, the pair of left and right wheel housings, and the cross member are integrally formed by die casting, but these do not necessarily have to be integrally formed by die casting, and these members may be formed separately. In this case, for example, the rear mount portion 32 may be connected to the front side member.

[0069] In addition, in this embodiment, the front mount portion 28 is provided in one location at approximately the center in the vehicle width direction, and the rear mount portions 32 are provided on the left and right in the vehicle width direction, but this is not limited to this.

[0070] Furthermore, in this embodiment, the front side members, the pair of left and right wheel housings, and the cross member are integrally molded by die casting, but this is not limiting. For example, they may be integrally molded from a resin such as CFRP.

[0071] Furthermore, in this embodiment, bent portions 34, 36 are provided at the bottom of the left and right side rails 18, respectively, but these bent portions 34, 36 are not necessarily required, and either one of the bent portions 34, 36 may be formed.

[0072] Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment may be appropriately combined with various modified examples, and the present invention may of course be embodied in various forms as long as it does not deviate from the gist of the present invention.

[0073] <Additional Notes> The vehicle underbody structure according to the present invention may be formed by appropriately combining the following configurations.

[0074] (Configuration 1) The vehicle undercarriage structure comprises a front mount portion provided on a cross member that forms the front side of a suspension member and extends in the vehicle width direction, the front mount portion being positioned below the center of gravity of the motor unit that drives the vehicle and supporting the front of the motor unit, and a rear mount portion being positioned on the opposite side of the front mount portion and above the vehicle with the center of gravity of the motor unit between them and supporting the rear of the motor unit.

[0075] (Configuration 2) The motor unit is disposed at the front of the vehicle, the front mount portion is provided at approximately the center in the vehicle width direction, and the rear mount portions are provided on the left and right sides in the vehicle width direction.

[0076] (Configuration 3) The rear mount portion is supported by a cast member that is integrally formed by die casting.

[0077] (Configuration 4) At the lower part of the side rail, which forms part of the suspension member and extends in the fore-and-aft direction of the vehicle, a first bend portion is provided on the front side of the front mount portion when viewed from the side of the vehicle, which serves as the starting point for the side rail to break when the vehicle is hit.

[0078] (Configuration 5) At the lower part of the side rail, which forms part of the suspension member and extends in the fore-and-aft direction of the vehicle, a second bend portion is provided on the rear side of the rear mount portion when viewed from the side of the vehicle, which serves as the starting point for the side rail to break when the vehicle is hit. [Explanation of symbols]

[0079] 10 vehicles 12 Front (front of vehicle) 14 Suspension member 18 Side rail 20 Cross member 26 Motor unit 28 Front mount 32 Rear mount 34 Bend part (first bend part) 36 Bend part (second bend part) G center of gravity

Claims

1. a front mount portion provided on a cross member that forms a front side of the suspension member and extends in the vehicle width direction, the front mount portion being positioned below the center of gravity of a motor unit that drives the vehicle and supports a front portion of the motor unit; a rear mount portion that is disposed on the opposite side of the front mount portion and above the vehicle with the center of gravity of the motor unit therebetween, and that supports a rear portion of the motor unit; A vehicle undercarriage comprising:

2. The motor unit is disposed at the front of the vehicle, 2. The vehicle undercarriage structure according to claim 1, wherein the front mount portion is provided at one location in a substantially central portion in the vehicle width direction, and the rear mount portions are provided on the left and right sides in the vehicle width direction.

3. 3. The vehicle underbody structure according to claim 2, wherein the rear mount portion is supported by a cast member integrally formed by die casting.

4. 2. The vehicle undercarriage structure according to claim 1, wherein a first bent portion is provided at a lower portion of a side rail that forms part of the suspension member and extends in the fore-and-aft direction of the vehicle, on the front side of the front mount portion as seen in a side view of the vehicle, the first bent portion being a starting point for bending the side rail in the event of a vehicle collision.

5. 2. The vehicle undercarriage structure according to claim 1, wherein a second bent portion is provided at a lower portion of a side rail that forms part of the suspension member and extends in the fore-and-aft direction of the vehicle, on the vehicle rear side of the rear mount portion as seen in a side view of the vehicle, and which serves as a starting point for bending the side rail in the event of a vehicle collision.

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