Vehicle rear structure

Abstract

To provide a vehicle rear structure making it possible to reliably protect a high-voltage component by further reliably tilting an auxiliary battery backward in a rear-end collision.SOLUTION: A vehicle rear structure includes: a frame 10 having a plurality of frame members mutually coupled; an auxiliary battery 24 fixed to the frame 10 near the rear end of a vehicle; a motor unit 22 that is disposed ahead of the auxiliary battery 24 in the vehicle and fixed to the frame 10; a lower back 30 that is disposed behind the auxiliary battery 24 in the vehicle and has a rising wall part 34 opposed to the auxiliary battery 24 in a vehicle width direction; and a projection 40 that juts out of the rising wall part 34 in a vehicular fore-and-aft direction and opposed to the auxiliary battery 24. The projection 40 is located at a position where, when the projection is pushed forward in the vehicle, the projection abuts against the auxiliary battery 24 below the center of gravity of the auxiliary battery 24.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This specification discloses a vehicle rear structure including a frame, an auxiliary battery fixed near the rear end of the frame, and a high-voltage component fixed to the frame forward of the auxiliary battery. [Background technology]

[0002] Generally, vehicles are equipped with high-voltage components such as a battery and a motor. Such high-voltage components are often fixed to the frame. For example, if the frame has a pair of side members extending in the fore-and-aft direction of the vehicle and a cross member spanning between the pair of side members, the high-voltage components may be fixed by being suspended from the cross member.

[0003] These high-voltage components are required not to interfere with other components during a rear-end collision, when an obstacle collides with the rear of the vehicle. Therefore, structures have been proposed that actively change the position or posture of high-voltage components so that they do not interfere with other components during a rear-end collision.

[0004] For example, some proposals have been made to provide weak or bent portions at predetermined positions on the side members so that when a collision load is applied to the rear end of the side members, the side members deform so as to become convex upward. By deforming the side members so as to become convex upward, high-voltage components connected to the side members via the cross members are lifted upward. This effectively prevents interference between the high-voltage components and other components, even if the high-voltage components move forward in a rear-end collision. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Publication No. 2005-247063 Summary of the Invention [Problem to be solved by the invention]

[0006] Due to the space available for arranging various components, the auxiliary battery may be fixed near the rear end of the frame. In this case, there is a risk that the side members will not deform as described above, and thus the high-voltage components will not move upward during a rear-end collision. Specifically, if the auxiliary battery is fixed near the rear end of the frame, the battery will be pressed forward by an obstacle during a rear-end collision. Because the obstacle presses against the entire rear end surface of the auxiliary battery, the battery will not tilt rearward. If the auxiliary battery does not tilt rearward, the frame to which the auxiliary battery is fixed, and in turn, the vicinity of the rear end of the side member, which is part of the frame, will not tilt forward. If the vicinity of the rear end of the side member does not tilt forward, the side members will not deform upward, and thus the high-voltage components will not be lifted.

[0007] Patent Document 1 discloses a technology for preventing deformation of a power storage mechanism, which is a high-voltage component, in a rear-end collision by devising the shape of a bracket that connects the power storage mechanism to a frame. However, Patent Document 1 does not consider lifting the power storage mechanism upward in a rear-end collision or fixing an auxiliary battery near the rear end of the frame. Therefore, Patent Document 1 cannot solve the above-mentioned problem.

[0008] Therefore, this specification discloses a vehicle rear structure that can more reliably tilt the auxiliary battery rearward during a rear collision, thereby more reliably protecting high-voltage components. [Means for solving the problem]

[0009] The vehicle rear structure disclosed in this specification comprises a frame having a plurality of skeletal members connected to each other, an auxiliary battery fixed to the frame near the rear end of the vehicle, a high-voltage component arranged forward of the auxiliary battery and fixed to the frame, a lower back arranged rearward of the auxiliary battery and having a vertical wall portion facing the auxiliary battery in the vehicle width direction, and a protrusion protruding from the vertical wall portion in the fore-and-aft direction of the vehicle and facing the auxiliary battery, wherein the protrusion is positioned so that when pushed forward of the vehicle, it abuts the auxiliary battery below the center of gravity of the auxiliary battery.

[0010] In this case, the vertical wall portion has a free lower end and can swing around an axis parallel to the vehicle width direction with its upper end as a fulcrum, the protrusion protrudes from the vertical wall portion toward the rear of the vehicle, and the protrusion may be attached at a position where the abutment point, which is the intersection of an arc with the fulcrum as its center and passing through the lower end of the base of the protrusion and the rear end surface of the auxiliary battery, is below the center of gravity of the auxiliary battery.

[0011] The protrusion may be attached at a position where the contact point is within the lower half of the range above the lower end of the auxiliary battery and below the center of gravity of the auxiliary battery.

[0012] The rear end surface of the protrusion may have a first pressure-receiving surface that is substantially parallel to the vertical direction, and a second pressure-receiving surface that extends in an upwardly forward direction from an upper end of the first pressure-receiving surface.

[0013] Furthermore, the vehicle may further include a bumper cover disposed behind the lower back for covering and concealing the lower back and the protrusion.

[0014] The protrusion may also have a tapered shape in which the height gradually decreases from the base to the tip.

[0015] The frame may also include a pair of side members extending in the fore-and-aft direction of the vehicle and a plurality of cross members spanning between the pair of side members, and in the event of a rear-end collision, the protrusion collides with the auxiliary battery, causing the auxiliary battery to tilt rearward and the side members to deform into an approximately arc-like shape with an upward convexity, thereby lifting the motor unit upward. [Effects of the Invention]

[0016] According to the vehicle rear structure disclosed in this specification, the auxiliary battery located behind the high-voltage components is likely to tilt backward during a rear-end collision. When the auxiliary battery tilts backward, the high-voltage components are likely to be lifted upward, which effectively prevents interference between the high-voltage components and other components and ultimately allows the high-voltage components to be appropriately protected. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic diagram of the rear of the vehicle as seen from below. [Figure 2] FIG. 2 is a schematic diagram of a cross section taken along the line AA in FIG. [Figure 3] 10A and 10B are diagrams briefly explaining the behavior of a frame in a rear collision. [Figure 4] 2 is a cross-sectional view of FIG. 1 taken along line B-B. [Figure 5A] 10A and 10B are diagrams illustrating changes around the auxiliary battery during a rear-end collision. [Figure 5B] 10A and 10B are diagrams illustrating changes around the auxiliary battery during a rear-end collision. [Figure 5C] 10A and 10B are diagrams illustrating changes around the auxiliary battery during a rear-end collision. [Figure 6] FIG. 10 is a diagram showing a rear-end collision when there is no protrusion. DETAILED DESCRIPTION OF THE INVENTION

[0018] The vehicle rear structure will be described below with reference to the drawings. Figures 1 and 2 are schematic diagrams of the vehicle rear structure, with Figure 1 being a view of the vehicle rear from below, and Figure 2 being a cross-sectional view taken along line AA in Figure 1. In each figure, "Fr," "Up," and "Rh" indicate the front, top, and right sides of the vehicle, respectively.

[0019] 1 and 2, the rear of the vehicle has a pair of side members 11 extending in the fore-and-aft direction of the vehicle, and a first cross member 12 and a second cross member 14 that are suspended between the pair of side members 11. The side members 11 and the cross members 12, 14 are all skeletal members made of steel, and are connected to each other to form the frame 10 of the vehicle.

[0020] As shown in Fig. 1, in order to ensure space for arranging the rear wheels (not shown), the side members 11 bend inward in the vehicle width direction near a first change position L1 located in front of the rear wheels, extend diagonally rearward, then change their extending direction near a second change position L2 located behind the first change position L1, and extend toward the rear of the vehicle. Also, as shown in Fig. 2, the side members 11 bend upward near the first change position L1 and extend diagonally upward, then change their extending direction near the second change position L2, and extend substantially horizontally.

[0021] The first cross member 12 is spanned across the pair of side members 11 at a position slightly rearward of the second change position L2. The second cross member 14 is spanned across the pair of side members 11 at a position rearward of the first cross member 12. Both ends of the first cross member 12 and the second cross member 14 in the vehicle width direction are welded to the side members 11.

[0022] The front ends of trailing arms 16 are fixed to the side members 11 near the first change position L1. As shown in FIG. 2, the trailing arms 16 extend substantially horizontally from near the first change position L1 toward the rear of the vehicle. An intermediate beam 18 spans between the pair of trailing arms 16. The intermediate beam 18 is a rigid body made of steel and is located slightly forward of the first cross member 12.

[0023] A motor unit 22 and an auxiliary battery 24 are fixed to the frame 10. The motor unit 22 is a high-voltage component that combines a drive motor, an inverter, and a reduction gear, which output power for driving the vehicle, and inputs and outputs high-voltage electric power. The motor unit 22 is connected to the first cross member 12 and the second cross member 14 via a motor mount bracket (not shown), and is suspended from the first cross member 12 and the second cross member 14. As is clear from FIG. 2 , the lower end of the motor unit 22 is located below the upper end of the intermediate beam 18, and the motor unit 22 and the intermediate beam 18 face each other in the fore-and-aft direction of the vehicle.

[0024] The auxiliary battery 24 stores power to be supplied to the auxiliaries. The upper end of the auxiliary battery 24 is connected to the second cross member 14 and the rear bumper 20, and the auxiliary battery 24 is suspended from the second cross member 14 and the rear bumper 20. As is clear from FIG. 1 , the motor unit 22 is disposed approximately in the center of the vehicle width direction, and the auxiliary battery 24 is disposed at an end in the vehicle width direction. The auxiliary battery 24 is located outward in the vehicle width direction from the end in the vehicle width direction of the motor unit 22, and the auxiliary battery 24 and the motor unit 22 do not face each other in the front-to-rear direction of the vehicle.

[0025] A rear bumper 20 that is long in the vehicle width direction is connected to the rear end of the frame 10. The rear bumper 20 includes a lower back, a rear bumper reinforcement (hereinafter referred to as "rear bumper R / F"), a bumper cover, etc. Furthermore, in this example, in the event of a rear-end collision in which an obstacle collides with the rear of the vehicle, a protrusion, which will be described later, is provided on the rear bumper 20 to adequately protect the motor unit 22, which is a high-voltage component. Before describing the configuration of the rear bumper 20 in detail, the behavior of the frame 10 during a rear-end collision will be briefly described with reference to FIG. 3.

[0026] 2, in this example, the motor unit 22, which is a high-voltage component, and the intermediate beam 18, which is a rigid body, face each other in the longitudinal direction of the vehicle. In this case, if the motor unit 22 receives a rear-end collision load and moves straight forward, there is a risk that the motor unit 22 will collide with the intermediate beam 18.

[0027] To prevent such a collision between the motor unit 22 and the intermediate beam 18, in this embodiment, the side member 11 is deformed into the shape shown in FIG. 3 , i.e., a substantially arc-shaped shape that is convex upward in the rearward direction, during a rear collision. Specifically, the portion of the side member 11 between the first change position L1 and the first cross member 12 is tilted significantly upward toward the rear, and the portion of the side member 11 located rearward of the second cross member 14 is tilted significantly upward toward the front. This deformation of the side member 11 causes the cross members 12, 14 and the motor unit 22 connected to the side member 11 to be lifted upward in the vehicle. This causes the motor unit 22 and the intermediate beam 18 to be misaligned in the vertical direction, effectively suppressing interference between them. Hereinafter, the target shape of the side member 11 after deformation during a rear collision, i.e., a substantially arc-shaped shape that is convex upward in the rearward direction and in which the motor unit 22 is lifted upward, as shown in FIG. 3 , will be referred to as the “retracted shape.”

[0028] Such deformation of the side members 11 into the retracted shape can be induced to some extent by forming weak portions or bending points in advance at predetermined positions of the side members 11. However, even if weak portions or the like are formed in advance, the side members 11 are unlikely to deform into the retracted shape in the event of a rear-end collision unless the auxiliary battery 24 tilts rearward.

[0029] That is, to place the side member 11 in the retracted shape, the portion of the side member 11 rearward of the second cross member 14 must be tilted rearward and downward. However, if the auxiliary battery 24, which is connected to the side member 11 via the second cross member 14 and the rear bumper 20, does not tilt rearward, the tilt of the side member 11 rearward and downward is also hindered. As a result, if the auxiliary battery 24 does not tilt rearward, the deformation of the side member 11 to the retracted shape is hindered, and there is a risk that the motor unit 22 will not be adequately protected. Therefore, in this example, a protrusion is provided on the rear bumper 20 to more reliably tilt the auxiliary battery 24 rearward in the event of a rear-end collision. This will be described below with reference to FIG. 4.

[0030] Figure 4 is a cross-sectional view taken along the line BB in Figure 1. As shown in Figure 4, the auxiliary battery 24 has a battery main body 26 and a battery case 28 that houses the battery main body 26. Flanges 28f, 28r protrude horizontally outward from the upper end of the battery case 28. The front flange 28f is joined to the upper surface of the second cross member 14, and the rear flange 28r is joined to a fastening portion 32 of the lower back 30, which will be described later.

[0031] The rear bumper 20 has a lower back 30, a rear bumper R / F 36, a bumper cover 38, and a protrusion 40. The lower back 30 includes a fastening portion 32 extending substantially horizontally and an upright wall portion 34 extending downward from the rear end of the fastening portion 32, and has a cross-sectional shape resembling an L-shape rotated 180 degrees. As described above, the rear flange 28r of the battery case 28 is joined to the upper surface of the fastening portion 32. Because the lower end of the upright wall portion 34 is a free end, when a force is applied to the upright wall portion 34 in the forward direction of the vehicle, the upright wall portion 34 swings about an axis parallel to the vehicle width direction, with its upper end as a fulcrum Ps.

[0032] The rear bumper R / F 36 is a member that reinforces the strength of the rear bumper 20. The rear bumper R / F 36 is a rectangular tubular member that has a substantially rectangular closed cross section and is long in the vehicle width direction. The rear bumper R / F 36 is disposed rearward of the vertical wall portion 34 and joined to the upper portion of the vertical wall portion 34.

[0033] The bumper cover 38 is a design panel that covers and conceals the lower back 30 and the rear bumper R / F 36 from the rear of the vehicle. As shown in Fig. 4, the cross section of the bumper cover 38 is a generally arc-shaped convex toward the rear of the vehicle. A gap large enough to accommodate a protrusion 40 is provided between the bumper cover 38 and the upright wall portion 34.

[0034] The protrusion 40 is a member that protrudes rearward from the vertical wall portion 34 of the lower back 30. The base end of the protrusion 40 is joined to the vertical wall portion 34. The protrusion 40 has a tapered shape, in which the vertical dimension continuously decreases from its base to its tip. By tapering the protrusion 40 in this manner, the weight of the protrusion 40 can be reduced while maintaining its strength. The rear end of the protrusion 40 serves as a pressure-receiving portion that receives a load during a rear-end collision. In this example, the rear end of the protrusion 40 is provided with a first pressure-receiving surface 42 and a second pressure-receiving surface 44 that is inclined relative to the first pressure-receiving surface 42. The first pressure-receiving surface 42 is a surface that is approximately parallel to the vertical direction under normal conditions (i.e., when the vertical wall portion 34 is not swinging). The second pressure-receiving surface 44 is a surface that contacts the upper edge of the first pressure-receiving surface 42 and is inclined in a forward-upward direction compared to the first pressure-receiving surface 42. By providing the first pressure receiving surface 42 and the second pressure receiving surface 44 at different angles, the rear collision load can be stably received in the event of a rear collision, which will be described later.

[0035] The protrusion 40 is provided in a range above the lower end of the auxiliary battery 24 and below the center of gravity G of the auxiliary battery 24. More precisely, in this example, the protrusion 40 is provided in a range Ha that is the lower half of the range above the lower end of the auxiliary battery 24 and below the center of gravity G of the auxiliary battery 24. Even more precisely, in this example, if the intersection of an arc 50 that is centered on the above-mentioned fulcrum Ps and passes through the lower end of the base of the protrusion 40 and the rear end surface of the auxiliary battery 24 is defined as a contact point Pc, the position of the protrusion 40 is determined so that this contact point Pc is located within the above-mentioned range Ha.

[0036] 4, the protrusion 40 is illustrated as a solid member, but the protrusion 40 may be hollow as long as it has sufficient strength to prevent deformation even when subjected to a collision load during a rear-end collision. Furthermore, the protrusion 40 may be made of either metal or resin as long as it has sufficient strength.

[0037] Next, the function of the protrusion 40 will be described with reference to Figures 5A to 5C. Figures 5A to 5C are diagrams illustrating changes in the vicinity of the auxiliary battery 24 during a rear-end collision. Consider a rear-end collision in which an obstacle 100 collides with the rear of the vehicle. Note that although the rear bumper R / F 36 and bumper cover 38 are not shown in Figures 5A to 5C, in reality, these are interposed between the protrusion 40 and the obstacle 100 in a crushed and compressed state in the fore-and-aft direction of the vehicle.

[0038] 5A, in the initial stage of a rear-end collision, the collision load from the obstacle 100 is input to the rear end of the protrusion 40 via the crushed and compressed rear bumper R / F 36 and bumper cover 38. At this time, the collision load is input mainly to the first pressure-receiving surface 42 of the rear end of the protrusion 40, which is approximately parallel to the vertical direction.

[0039] When subjected to a collision load, the upright wall portion 34 of the lower back 30 swings around the fulcrum Ps as shown in FIG. 5B . This swinging causes the posture of the protrusion 40 to change. As a result, after the swinging, the second pressure-receiving surface 44 becomes substantially parallel to the vertical direction. In this case, the collision load is received by the second pressure-receiving surface 44. In other words, in this example, by providing the first pressure-receiving surface 42 and the second pressure-receiving surface 44 at different angles to each other at the rear end of the protrusion 40, the collision load can be continuously received by the surface even if the posture of the protrusion 40 changes. By receiving the collision load by the surface, most of the collision load can be reliably transmitted to the protrusion 40.

[0040] When the lower back 30 swings sufficiently, as shown in FIG. 5B , the lower root end of the protrusion 40 presses against the rear end surface of the auxiliary battery 24 at the contact point Pc. As described above, this contact point Pc is located below the center of gravity G of the auxiliary battery 24. Therefore, when the protrusion 40 presses the auxiliary battery 24 rearward due to a collision load, the auxiliary battery 24 tilts toward the rear of the vehicle as shown in FIG. 5C . As the auxiliary battery 24 tilts rearward, the portion of the side member 11 rearward of the second cross member 14 tends to tilt upward toward the front as shown in FIG. 3 . As a result, the side member 11 is induced to deform into the target shape, and the motor unit 22 is lifted upward. This prevents interference between the motor unit 22 and the intermediate beam 18 and appropriately protects the motor unit 22, which is a high-voltage component.

[0041] For reference, the behavior of the auxiliary battery 24 in the absence of the protrusion 40 will be described with reference to FIG. 6 . As shown in FIG. 6 , in the absence of the protrusion 40, the lower back 30, bumper cover 38, and other components, which are crushed and compressed in the fore-and-aft direction of the vehicle, are interposed between the obstacle 100 and the auxiliary battery 24 during a rear-end collision. At this time, the pressure from the obstacle 100 is received by the entire rear end surface of the auxiliary battery 24. In this case, even if the auxiliary battery 24 attempts to tilt rearward, i.e., even if the upper part of the auxiliary battery 24 attempts to move rearward relative to the lower part, this movement is restricted by the obstacle 100. As a result, in the absence of the protrusion 40, the obstacle 100 restricts the rearward tilt of the auxiliary battery 24, thereby inhibiting the deformation of the side member 11 into the retracted shape. On the other hand, when the protrusion 40 is provided as in this example, the collision load is below the center of gravity G of the auxiliary battery 24, as described above. Since the force is input to the contact point Pc, the auxiliary battery 24 is induced to tilt backward, which causes the side member 11 to deform into the target shape and eventually induces the lifting of the motor unit 22. This allows the high-voltage components to be appropriately protected.

[0042] The configuration described above is merely an example, and other configurations may be modified as long as the protrusion 40, which protrudes in the vehicle fore-and-aft direction, is provided on the upright wall portion 34 of the lower back 30 below the center of gravity G of the auxiliary battery 24. For example, the shape of the protrusion 40 may be modified as appropriate as long as it can input a collision load to the portion of the auxiliary battery 24 below the center of gravity G during a rear-end collision. For example, in this example, the rear end of the protrusion 40 is provided with a first pressure-receiving surface 42 and a second pressure-receiving surface 44, but the number of surfaces constituting the rear end may be one or three or more. Furthermore, in this example, the motor unit 22 is used as an example of a high-voltage component, but the high-voltage component may be another component, such as a main battery. [Explanation of symbols]

[0043] 10 frame, 11 side member, 12 first cross member, 14 second cross member, 16 trailing arm, 18 intermediate beam, 20 rear bumper, 22 motor unit, 24 auxiliary battery, 26 battery body, 28 battery case, 30 lower back, 32 fastening portion, 34 vertical wall portion, 38 bumper cover, 40 protrusion, 42 first pressure receiving surface, 44 second pressure receiving surface, 50 arc, 100 obstacle, G center of gravity, Pc contact point, Ps fulcrum.

Claims

1. a frame having a plurality of skeletal members connected to one another; an auxiliary battery fixed to the frame near the rear end of the vehicle; a high-voltage component disposed forward of the auxiliary battery and fixed to the frame; a lower back disposed behind the auxiliary battery and having a vertical wall portion facing the auxiliary battery in a vehicle width direction; a protrusion protruding from the vertical wall portion in the vehicle front-rear direction and facing the auxiliary battery; the protrusion is provided at a position where it comes into contact with the auxiliary battery below the center of gravity of the auxiliary battery when the protrusion is pushed forward of the vehicle. A vehicle rear structure characterized by:

2. 2. The vehicle rear structure according to claim 1, The upright wall portion has a lower end that is a free end and is swingable around an axis parallel to the vehicle width direction with its upper end as a fulcrum, the protrusion protrudes from the upright wall portion toward the rear of the vehicle, The protrusion is attached at a position where an abutment point, which is an intersection point between an arc having the fulcrum as its center and passing through a base lower end of the protrusion and a rear end surface of the auxiliary battery, is below the center of gravity of the auxiliary battery. A vehicle rear structure characterized by:

3. 3. The vehicle rear structure according to claim 2, A vehicle rear structure characterized in that the protrusion is attached at a position where the contact point is within the lower half of the range above the lower end of the auxiliary battery and below the center of gravity of the auxiliary battery.

4. 4. The vehicle rear structure according to claim 2 or 3, A vehicle rear structure characterized in that the rear end surface of the protrusion has a first pressure-receiving surface that is approximately parallel to the vertical direction, and a second pressure-receiving surface that extends in an upward direction toward the front from the upper end of the first pressure-receiving surface.

Images