Vehicle battery unit mounting structure

Abstract

To provide a battery unit loading structure that suppresses a deformation amount of a battery case.SOLUTION: A battery unit loading structure includes: a pair of right and left rear frames 1 extending along a back-and-forth direction of a vehicle M; a battery unit 10 formed by including a case 12 in which a battery is stored and which is arranged between the pair of rear frames, and a battery frame 11 which is provided so as to be integrated at a part of a peripheral edge of the case at an opening side, extends in a vehicle widthwise direction, has protrusions 11ra protruding in the vehicle widthwise direction beyond a clearance between the pair of rear frames and provided at respective ends, and has the protrusions fastened to the respective upper surfaces of the pair of rear frames; and a reinforcement plate 14 provided so as to be integrated with the rear frames at respective regions where the pair of rear frames and the protrusions are respectively fastened with each other. The reinforcement plate is placed so as to extend in the back-and-forth direction of the vehicle at each region where each rear frame and each protrusion are fastened with each other. The rear frames and the battery frame are fastened with each other at a first fastening portion RS located at the back side of the protrusion and at a second fastening portion FS located at the front side of the protrusion.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This invention relates to a mounting structure of a high-voltage battery unit mounted on a vehicle such as an automobile.

Background Art

[0002] In recent years, in vehicles such as automobiles, in addition to a conventional internal combustion engine (engine), hybrid vehicles equipped with an electric motor (electric motor) as a drive source, electric vehicles that use an electric motor as a drive source, etc. have been generally put into practical use and are becoming widely popular.

[0003] In this type of vehicle, a high-voltage battery unit (hereinafter simply referred to as a battery unit) including a high-voltage battery for driving an electric motor (hereinafter simply referred to as a battery) and a battery case for housing this battery is mounted. In a conventional vehicle, the battery unit is generally arranged at the bottom surface portion of the rear luggage room of the vehicle.

[0004] This type of battery unit tends to increase in outer size as the battery capacity increases. Therefore, when mounting a larger-capacity battery on a vehicle, there is a tendency for the amount of vehicle body stroke, especially during a rear collision, to decrease.

[0005] Conventionally, at the time of a rear collision of a vehicle, a method has been adopted to absorb the collision energy by deforming the bumper beam and the rear frame, thereby suppressing the deformation of the battery unit due to the collision energy. Since the battery adopted in the battery unit in this type of vehicle is a high-voltage battery, there is a desire to avoid as much as possible the contact between a part of the battery case crushed due to the deformation of the battery case and the battery, or an increase in the input of collision energy to the battery.

[0006] As mentioned above, as the battery unit gets larger, the amount of body stroke during a collision decreases, which means that the body frame members cannot adequately absorb the collision energy through deformation. As a result, the collision energy input to the battery case increases. Therefore, measures such as making the battery case itself more robust are necessary. However, adopting measures to ensure the strength of the battery case increases its weight and also raises manufacturing costs.

[0007] Therefore, various proposals have been made in the past, such as in Japanese Patent Publication No. 2017-114190, Japanese Patent Publication No. 2012-114069, and Japanese Patent Publication No. 2016-164051, for example, regarding battery unit mounting structures that aim to reduce the weight and manufacturing cost of the battery case while suppressing the input of collision energy to the battery case during a collision.

[0008] The battery unit mounting structure disclosed in the above-mentioned Japanese Patent Publication No. 2017-114190 consists of a battery case for housing the battery and a suspension frame that supports the battery case in a suspended manner. A weak point that bends when subjected to impact is provided near the fastening portion of the suspension frame to the vehicle body frame, and the structure reduces the impact on the battery case by moving the battery case forward.

[0009] The battery unit mounting structure disclosed in Japanese Patent Publication No. 2012-114069 is a structure that suppresses the load on the battery unit by providing a reinforcing member on the lower or upper surface of the battery unit and transmitting a load (for example, a load due to a side collision) applied to one of a pair of left and right vehicle body frame members to the other vehicle body frame member.

[0010] The battery unit mounting structure disclosed in the above-mentioned Japanese Patent Publication No. 2016-164051 is a structure that suppresses deformation of the battery case and damage to the battery housed inside the case by providing a reinforcing member on the bottom surface of the battery case and distributing the load applied to the case wall surface. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2017-114190 [Patent Document 2] Japanese Patent Publication No. 2012-114069 [Patent Document 3] Japanese Patent Publication No. 2016-164051 [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] However, even in the conventional battery unit mounting structures disclosed in the aforementioned publications, there is still room for improvement in efficiently absorbing externally input collision energy and suppressing deformation of the battery case.

[0013] The object of the present invention is to provide a vehicle battery unit mounting structure that can efficiently increase the amount of collision energy absorbed and suppress the amount of deformation of the battery case, while reducing the weight and manufacturing cost of the battery case. [Means for solving the problem]

[0014] To achieve the above objective, a battery unit mounting structure for a vehicle according to one aspect of the present invention comprises: a battery unit formed by: a pair of left and right rear frames extending along the longitudinal direction of the vehicle; a housing in which a battery is housed and positioned between the pair of rear frames; a battery frame integrally provided on a part of the opening-side peripheral edge of the housing and extending in the vehicle width direction, having protruding portions at both ends that protrude in the vehicle width direction beyond the distance between the pair of rear frames, and the protruding portions being fixed to the upper surfaces of the pair of rear frames; and reinforcing plates integrally provided with the rear frames in each region where the pair of rear frames and the protruding portions are fixed, wherein the reinforcing plates are arranged to extend in the longitudinal direction of the vehicle in the regions where the rear frames and the protruding portions are fixed. The reinforcing plate and The rear frame and the battery frame are fixed together at a first fastening portion located behind the protruding portion and a second fastening portion located in front of the protruding portion. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a vehicle battery unit mounting structure that can efficiently increase the amount of collision energy absorbed and suppress the amount of deformation of the battery case, while reducing the weight and manufacturing cost of the battery case. [Brief explanation of the drawing]

[0016] [Figure 1] A schematic diagram of a vehicle battery unit mounting structure according to one embodiment of the present invention. [Figure 2] A conceptual diagram showing the battery unit mounting structure in a cross-section along the line [2]-[2] in Figure 1. [Figure 3] Figure 1 is a perspective view showing only the main parts of the battery unit, partially disassembled. [Figure 4] Figure 3 is a schematic perspective view showing the main structure of the rear battery frame within the battery unit. [Figure 5]Perspective view showing an enlarged view of the rear area (the area indicated by reference numeral [4] in FIG. 1) of the joint region between the battery frame and the rear side frame in the battery unit of FIG. 3. [Figure 6] FIG. 6 is an exploded perspective view showing FIG. 5 decomposed. [Figure 7] Plan view of FIG. 5 as seen from above. [Figure 8] Perspective view showing an enlarged view of the front area (the area indicated by reference numeral [8] in FIG. 1) of the joint region between the battery frame and the rear side frame in the battery unit of FIG. 3. [Figure 9] Exploded perspective view showing FIG. 8 decomposed. [Figure 10] Diagram for explaining the operation when a collision impact or the like is applied to the battery unit mounting structure of the present embodiment from the rear of the vehicle.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described with reference to the illustrated embodiments. Each of the drawings used in the following description is a schematic illustration, and in order to show each component in a size that can be recognized on the drawing, the dimensional relationships, scales, etc. of each member may be shown differently for each component. Therefore, the present invention is not limited only to the forms shown in the drawings with respect to the quantity of each component described in each drawing, the shape of each component, the ratio of the size of each component, the relative positional relationship of each component, etc.

[0018] The battery unit mounting structure of a vehicle according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of the battery unit mounting structure of a vehicle according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing the battery unit mounting structure in a cross-sectional view taken along line [2]-[2] of FIG. 1.

[0019] Figure 3 is a perspective view showing only the main parts of the battery unit from Figure 1, partially disassembled. In Figure 3, to avoid complexity in the drawing, the illustration of each component housed inside the battery unit is omitted, and only the components directly related to the present invention (basic components of the battery unit) are shown.

[0020] Figures 4 to 7 are enlarged views of the rear region (indicated by the reference numeral [4] in Figure 1) of the joint area between the battery frame and the rear side frame in the battery unit. Of these, Figure 4 is a schematic perspective view showing the structure of the main part of the rear battery frame. In Figure 4, the cross-section is shown along the line [4]-[4] in Figure 3. Here, Figure 4 shows the rear battery frame and rear bracket assembled.

[0021] Figure 5 is an enlarged perspective view of the main part showing the assembled state of the joint between the rear battery frame and the rear side frame in the battery unit (the area indicated by reference numeral [4] in Figure 1). Figure 6 is an exploded perspective view of Figure 5. Figure 7 is a top view of Figure 5.

[0022] Figures 8 and 9 are enlarged views of the front region (indicated by the reference numeral [8] in Figure 1) of the connection area between the battery frame and the rear side frame in the battery unit. Of these, Figure 8 is an enlarged perspective view of the main part showing the connection state between the front battery frame, the rear side frame and the cross member in the battery unit. Figure 9 is an exploded perspective view of Figure 8.

[0023] In Figures 1 to 9, the direction indicated by arrow symbol F represents the front side of the vehicle. Similarly, the direction indicated by arrow symbol R represents the rear side of the vehicle. In the following explanation, "front side" refers to the side indicated by arrow symbol F. Likewise, in the following explanation, "rear side" refers to the side indicated by arrow symbol R (and the same applies to Figure 10, which will be discussed later).

[0024] First, the general outline of the battery unit mounting structure of a vehicle according to one embodiment of the present invention will be briefly described below with reference to Figures 1 and 2.

[0025] As shown in Figures 1 and 2, the vehicle M of this embodiment has a battery unit 10 mounted on the floor panel 6 of the rear luggage compartment M1 (see Figure 2). This battery unit 10, as will be described in detail later, consists of a battery case 12 and a battery frame 11 provided on the periphery of the opening side of the battery case 12 (see Figure 2 or Figure 3, which will be described later). Inside the battery unit 10 are a battery (storage battery) 100 and auxiliary equipment 101, etc.

[0026] A pair of rear frames, or rear side frames 1, are provided on the rear side of the vehicle M. The pair of rear side frames 1 extend along the longitudinal direction of the vehicle and are positioned near the left and right edges at intervals in the width direction of the vehicle M.

[0027] Furthermore, as will be described in more detail later, the front battery frame 11f and the rear battery frame 11r of the battery unit 10, which are provided in the longitudinal direction of the vehicle M, are fixed to the upper surface of the pair of rear side frames 1.

[0028] An extension 3 is attached to each rear end of a pair of rear side frames 1. Each extension 3 is attached to a rear bumper beam 2 that extends in the vehicle width direction.

[0029] Furthermore, the rear ends of the pair of rear side frames 1 are connected by a first rear cross member 4 (not shown in Figures 1 and 2; see Figure 10 later) that extends in the left and right directions in the vehicle width direction. Similarly, the front ends of the rear side frames 1 are connected by a second rear cross member 5 (not shown in Figure 1; see Figure 2 and Figure 9 later) that extends in the left and right directions in the vehicle width direction.

[0030] As shown in Figure 2, undercarriage components 102, a muffler 103, etc., are arranged on the outside of the floor panel 6 of the rear luggage compartment M1. Also, seats 104, etc., are arranged on the front side of the rear luggage compartment M1. Note that these component units are not directly related to the present invention, so only their arrangement is illustrated with dashed lines in Figure 2. This configuration is substantially the same as the internal configuration of conventional automobiles and other vehicles.

[0031] In Figure 2, the symbol L indicates the shortest distance between the inner wall surface of the rear battery frame 11r or battery case 12 (rear end side) and the outer wall surface (rear end side) of the battery 100. This shortest distance L refers to the range within which, if the rear battery frame 11r or battery case 12 (rear end side) is crushed due to a rearward impact, the components on the battery case side will not come into contact with the internal battery 100. Therefore, it is considered that crushing of the rear battery frame 11r or battery case 12 is permissible within the range of the shortest distance L.

[0032] Next, the details of the battery unit mounting structure of this embodiment will be described below with reference to Figures 3 to 9. The basic configuration of the battery unit 10 consists of a battery frame 11, a battery case 12, a rear bracket 13, etc., as shown in Figure 3, etc.

[0033] The battery frame 11 consists of a rear battery frame 11r, a front battery frame 11f, and two side battery frames 11s. The battery frame 11, as a whole, forms a substantially rectangular frame with its four frame members (11r, 11f, 11s). In this case, the rear battery frame 11r has a protruding portion 11ra that extends a predetermined length in the width direction beyond the two side battery frames 11s (see Figure 3). This protruding portion 11ra is the part that is placed on the upper surface of the rear side frame 1 and fastened and fixed.

[0034] The rear battery frame 11r, the front battery frame 11f, and the two side battery frames 11s each have a roughly channel-shaped cross-section (a so-called hat shape). The rear bracket 13 is joined to the bottom surface of the rear battery frame 11r. As a result, the rear battery frame 11r and the rear bracket 13 form a closed cross-section (see Figure 4).

[0035] The battery case 12 is a dish-shaped housing with a rectangular opening, which houses the battery inside. The battery case 12 is positioned within a rectangular frame formed by the rear battery frame 11r, the front battery frame 11f, and two side battery frames 11s. For this purpose, a flange (not shown) is formed on the peripheral edge of the opening side of the battery case 12. The battery frame 11 is joined to this flange in a manner in which it is placed.

[0036] The rear bracket 13 is joined to the bottom surface of the rear battery frame 11r. The rear bracket 13 is then placed on the upper surface portion near the rear end of each of the pair of rear side frames 1. In this state, the rear bracket 13 is fixed to a predetermined portion near the rear end of each of the pair of rear side frames 1.

[0037] To this end, one rear through-hole 13a and two front through-holes 13b are formed at predetermined positions near both ends of the rear bracket 13. As shown in Figures 5 and 6, fastening bolts 15 for the reinforcing plate 14 provided on the rear side frame 1 are inserted through the rear through-hole 13a. Fastening nuts 17 are screwed onto these fastening bolts 15.

[0038] Furthermore, two fastening bolts 16r are inserted through the front through-hole 13b. These two fastening bolts 16r are screwed into fastening nuts (not shown) of the reinforcing plate 14. In this way, the rear bracket 13 is fastened and fixed to the pair of rear side frames 1.

[0039] Furthermore, the front battery frame 11f is fixed to the second rear cross member 5, as shown in Figures 8 and 9. For this purpose, two through holes 11a (see Figures 3 and 9) are formed at predetermined positions near both ends of the front battery frame 11f. Two fastening bolts 16f are inserted through these two through holes 11a, as shown in Figures 8 and 9. These two fastening bolts 16f are screwed into fastening nuts (not shown) that are joined to the back surface of two nut placement holes 5a (see Figure 9) of the second rear cross member 5. In this way, the front battery frame 11f is fastened and fixed to the second rear cross member 5. The second rear cross member 5 is formed by joining parts of two members 5x and 5y, which are formed by bending plate-shaped members.

[0040] On the other hand, reinforcing plates 14 are provided at predetermined locations near the rear end of each of the pair of rear side frames 1 (see reference numeral P in Figures 5 to 7). These reinforcing plates 14 are provided to improve the strength (especially the bending strength) in a predetermined area (here, within the range of area P) of the pair of rear side frames 1. Here, the area indicated by reference numeral P in Figures 5 to 7 will be referred to as the reinforced area P in the following description. Also, in Figure 7, the part indicated by reference numeral B1 is the rear end of the pair of rear side frames 1 and is the joint with the extension 3 (not shown in Figure 7). The part indicated by reference numeral B2 indicates the boundary between the reinforced area P and the normal area of ​​the pair of rear side frames 1. As will be explained in detail in the description of the operation below, the joint part B1 and the boundary part B2 are the locations where bending occurs in the rear side frame 1 when a collision impact or the like is applied to the rear side frame 1 from a predetermined direction.

[0041] The reinforcing plate 14 consists of a plate member formed by bending to conform to the shape of the inner surface of each of the pair of rear side frames 1. The reinforcing plate 14 is joined to the back side of each rear side frame 1. In this case, the parts indicated by the symbol WP in Figures 6 and 7 indicate multiple joining points (specifically, for example, multiple spot welding points) of the reinforcing plate 14 to the rear side frame 1. In this way, the reinforcing plate 14 is firmly joined to predetermined parts of the pair of rear side frames 1.

[0042] Furthermore, as shown in Figure 6, the reinforcing plate 14 has a bolt insertion hole 14a and two nut placement holes 14b. The bolt insertion hole 14a is formed at a predetermined location near the rear end of the reinforcing plate 14. The two nut placement holes 14b are formed at a predetermined location near the front end of the reinforcing plate 14.

[0043] Here, the area where the bolt insertion hole 14a is located will be referred to as the rear fastening part RS, which is the first fastening part, in the following description (see Figure 7). Also, the area where the two nut placement holes 14b are located will be referred to as the front fastening part FS, which is the second fastening part, in the following description (see Figure 7).

[0044] In this case, the front fastening portion FS has more fastening points than the rear fastening portion RS. Specifically, for example, the rear fastening portion RS is fastened and secured by one fastening point (fastening bolt 15 and fastening nut 17). The front fastening portion FS is fastened and secured by two fastening points (two fastening bolts 16r).

[0045] A fastening bolt 15 is joined to the bolt insertion hole 14a of the reinforcing plate 14 in a manner that it protrudes from the back surface toward the top surface. This fastening bolt 15 passes through the bolt insertion hole 14a of the reinforcing plate 14, through the through hole 1a of the rear side frame 1, and then through the rear through hole 13a of the rear bracket 13. A fastening nut 17 is then screwed onto the fastening bolt 15. As a result, the battery frame 11 (rear bracket 13) is fastened and fixed to the rear side frame 1 at the rear fastening portion RS.

[0046] Furthermore, fastening nuts (not shown; hereinafter referred to as back nuts) are attached to the back side of the reinforcing plate 14 in the two nut placement holes 14b. Two fastening bolts 16r are screwed into these back nuts (not shown) of the two nut placement holes 14b, passing through the front through hole 13b of the rear bracket 13, then through the through hole 1b of the rear side frame 1, and then through the nut placement holes 14b of the reinforcing plate 14. As a result, the battery frame 11 (rear bracket 13) is fastened and fixed to the rear side frame 1 at the front fastening portion FS.

[0047] As described above, in the structure of this embodiment, the rear fastening portion RS and the front fastening portion FS are positioned to sandwich the rear battery frame 11r of the battery frame 11 in the front-rear direction (see Figure 7, etc.).

[0048] Furthermore, in the structure of this embodiment, on the rear side frame 1, the rear fastening portion RS is located near the boundary portion B2 with the reinforced area P provided by the reinforcing plate 14, and is positioned further forward than the boundary portion B2. The front fastening portion FS is positioned even further forward than the rear fastening portion RS. In this case, the rear fastening portion RS and the front fastening portion FS are positioned with the rear battery frame 11r in between.

[0049] Furthermore, the reinforcing plate 14 is configured such that the area extending towards the front of the vehicle M is larger than the area extending towards the rear of the vehicle M, with respect to the region where the rear side frame 1 and the protruding portion 11ra are fixed.

[0050] The operation of the battery unit mounting structure of this embodiment, configured as described above, will be explained below with reference to Figure 10. Figure 10 is a diagram illustrating the operation of the battery unit mounting structure of this embodiment when a collision or other impact is applied from the rear of the vehicle.

[0051] The action described in Figure 10 assumes a case where a roughly cylindrical object (the test pole indicated by symbol T) collides with the vehicle M at approximately its center in the width direction, from the rear of the vehicle M, along the vehicle M's longitudinal axis. Note that Figure 10 shows approximately one half of the vehicle M. First, at the position shown in Figure 10(A), the test pole T is assumed to collide with the rear bumper beam 2 from the direction of arrow G (rear) in Figure 10(A), approximately at the center of the beam. Here, the collision start position between the test pole T and the rear bumper beam 2 is indicated by the symbol A in Figure 10(A), and the collision start point is indicated by the symbol C in the same Figure 10(A).

[0052] As the test pole T moves further in the direction of arrow G from the collision initiation point C, the collision energy causes the rear bumper beam 2 to bend inward towards the vehicle body M around the collision point C1. As a result, the rear bumper beam 2 flexes inward towards the vehicle body around the collision point C1.

[0053] At this time, near each end of each rear bumper beam 2, it is joined to the respective rear ends of each extension 3. Also, each front end of each extension 3 is joined to the respective rear ends of each rear side frame 1. Therefore, as the test pole T moves from the collision initiation point C toward the direction of arrow G (front side F), as shown in Figure 10(A), the rear bumper beam 2 flexes, and each extension 3 bends inward at the joint portion B1 with the rear end of each rear side frame 1. In Figure 10(A), the symbol D1 indicates the inclination (flex) of the extension 3 due to bending. Then, as shown in Figure 10(A), the test pole T crushes the rear bumper beam 2, and a part of the rear bumper beam 2 collides with the first rear cross member 4. This also initiates the crushing of the first rear cross member 4.

[0054] After the state shown in Figure 10(A), as the test pole T moves further from the impact point C1 in the direction of arrow G to the impact point C2 as shown in Figure 10(B), the crushing of the rear bumper beam 2 and the first rear cross member 4 progresses. As a result, the deflection (inward tilt) of the extension 3 due to bending increases as shown by the symbol D2 in Figure 10(B). At the same time, the rear end portion of the rear side frame 1 begins to bend from near the boundary portion B2. However, the rear side frame 1 and the rear bracket 13 remain fastened at the rear fastening portion RS.

[0055] Here, the rear end portion of the rear side frame 1 absorbs collision energy by bending inward from the vicinity of the boundary portion B2 with the reinforcing plate 14. As a result, the collision energy applied to the rear fastening portion RS is suppressed. Therefore, damage to the rear fastening portion RS is suppressed.

[0056] Furthermore, at this time, the longitudinal length of the rear side frame 1 behind the boundary portion B2 is relatively short compared to the total length of the rear side frame 1. Therefore, the inclination of the rear end portion of the rear side frame 1 that bends near the boundary portion B2 is suppressed.

[0057] Thus, in the structure according to this embodiment, when the vehicle M receives collision energy from a rearward collision, the inward tilting of the rear side frame 1 itself is suppressed. As a result, the time it takes for the crushing of the rear bumper beam 2 and the first rear cross member 4 to reach the rear battery frame 11r can be reduced. Therefore, damage to the rear battery frame 11r is suppressed.

[0058] After the state shown in Figure 10(B), if the test pole T moves further from the collision point C2 in the direction of arrow G, eventually the rear through hole 13a of the rear bracket 13 will be cut at the rear fastening portion RS, as shown in Figure 10(C). As a result, the fastening force at the rear fastening portion RS is released.

[0059] As a result, the rear end portion of the rear side frame 1 experiences increased deflection (inward tilt) due to bending, as shown by the reference numeral D3 in Figure 10(C). However, at this point, the rear side frame 1 and the rear bracket 13 are firmly fastened at the front fastening portion FS (two-point fastening). Therefore, at this time, the rear side of the rear side frame 1 will bend from the front fastening portion FS.

[0060] In this case, for example, if the front fastening portion FS is not provided, the rear side frame 1 will tilt inward as a whole at a predetermined portion further forward.

[0061] Therefore, in the structure of this embodiment, by providing a front fastening portion FS in addition to the rear fastening portion RS, for example, at the time shown in Figure 10(C), the rear side frame 1 is configured to flex only from the rear side of the front fastening portion FS. In this case, the tilt of the rear side frame 1 is suppressed compared to the case where the rear side frame 1 tilts as a whole.

[0062] Therefore, the amount of movement from collision point C2 in Figure 10(B) to collision point C3 in Figure 10(C) is suppressed. This suppresses damage to the rear battery frame 11r. Here, for example, in this embodiment, damage to the rear battery frame 11r in the forward direction is suppressed to within a predetermined separation distance L, so that the rear battery frame 11r does not come into contact with the battery inside the case.

[0063] As the test pole T moves further in the direction of arrow G, the front through-hole 13b of the rear bracket 13 is eventually severed at the front fastening portion FS, as shown in Figure 10(C). At the same time, the collision energy is transmitted through the two side battery frames 11s to the front battery frame 11f. Consequently, the connection between the front battery frame 11f and the second rear cross member 5 is broken.

[0064] Specifically, for example, when collision energy is transmitted to the front battery frame 11f, the fastening state between the front battery frame 11f and the second cross member 5 by the two fastening bolts 16f is maintained, but the joint between the two members 5x and 5y that make up the second cross member 5 is broken. As a result, the battery unit 10, having received the collision energy, becomes capable of moving forward of the vehicle M.

[0065] In other words, at this point, the battery unit 10 is essentially released from its fixed position to the rear side frame 1. Therefore, the collision energy received by the battery unit 10 at this time causes it to move forward relative to the vehicle M. As a result, the battery unit 10 will not be damaged by the collision energy it receives from this point onward.

[0066] As described above, according to the above embodiment, the rear battery frame 11r of the battery frame 11 in the battery unit 10, which extends in the vehicle width direction of the vehicle M, has protruding portions 11ra at both ends that protrude in the vehicle width direction of the rear side frame 1. The battery frame 10 is fixed to the pair of rear side frames 1 by fastening and fixing each protruding portion 11ra to the respective upper surfaces of the pair of rear side frames 1.

[0067] Furthermore, a reinforcing plate 14 is provided integrally with each rear side frame 1 in each region where the pair of rear side frames 1 and the protrusion 11ra are fixed. This reinforcing plate 14 is arranged to extend in the longitudinal direction of the vehicle in the region where the rear side frames 1 and the protrusion 11ra are fixed. The rear side frames 1 and the battery frame 11 are fixed at a first fastening part (rear fastening part RS) located behind the protrusion 11ra and a second fastening part (front fastening part FS) located in front of the protrusion 11ra. In other words, the first fastening part (rear fastening part RS) and the second fastening part (front fastening part FS) are positioned to sandwich the protrusion 11ra in the longitudinal direction of the vehicle M.

[0068] Furthermore, the second fastening section (front fastening section FS) has more fastening points than the first fastening section (rear fastening section RS). Specifically, the second fastening section (front fastening section FS) has two fastening points, while the first fastening section (rear fastening section RS) has one fastening point.

[0069] Furthermore, the reinforcing plate 14 is configured such that the area extending towards the front of the vehicle M is larger than the area extending towards the rear of the vehicle M, with respect to the region where the rear side frame 1 and the protrusion 11ra are fixed.

[0070] With this configuration, according to this embodiment, when a collision impact or the like is applied to the vehicle M from the rear, the collision energy can be absorbed by bending the rear side frame 1 at a predetermined part near the rear end, i.e., the boundary portion B2 with the reinforcing plate 14.

[0071] Furthermore, by providing the first fastening portion (rear fastening portion RS) and the second fastening portion (front fastening portion FS), deformation of the rear side frame 1 (inward bending due to bending) can be suppressed. This suppresses the collision energy applied to the case member (rear battery frame 11r) of the battery unit 10, and thus prevents damage to the case member (rear battery frame 11r).

[0072] Furthermore, by sequentially breaking the first fastening portion (rear fastening portion RS) and the second fastening portion (front fastening portion FS) before the case member (rear battery frame 11r) deforms beyond a predetermined level, the battery unit 10 can be moved forward. Therefore, deformation of the case member (rear battery frame 11r) can be suppressed.

[0073] In this way, in this embodiment, deformation of the rear side frame 1 can be suppressed, and the amount of deformation of the battery case can be minimized.

[0074] The present invention is not limited to the embodiments described above, and various modifications and applications can be implemented without departing from the spirit of the invention. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of the multiple constituent elements disclosed. For example, if the problem that the invention aims to solve can be solved and the effects of the invention can be obtained even if some constituent elements are deleted from all the constituent elements shown in one embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. Furthermore, constituent elements from different embodiments may be combined as appropriate. This invention is not limited by any particular embodiment other than being limited by the appended claims. [Explanation of symbols]

[0075] 1…Rear side frame 1a,1b...Through hole 2…Rear bumper beam 3…Extension 5…Second cross member 5a... Nut placement hole 6…Floor panel 10…Battery unit 11…Battery frame 11a...Through hole 11f... Front battery frame 11r... Rear battery frame 11ra…Protrusion 11s…Side battery frame 12…Battery case 13…Rear bracket 13a...Rear through hole 13b...Front through hole 14…Reinforcement plate 14a... Bolt insertion hole 14b...Nut placement holes 15… Fastening bolts 16f, 16r… fastening bolts 17... Nut 100... Battery (rechargeable battery) 101…Auxiliary equipment 102... Suspension parts 103... Muffler 104...sheet M... Vehicle M1... Rear luggage compartment P...Reinforcement area FS...Front fastening part RS…Rear side fastening part

Claims

1. A pair of left and right rear frames extending along the front-to-rear direction of the vehicle, A battery unit is formed comprising a housing in which a battery is housed and positioned between the pair of rear frames, and a battery frame integrally provided on a part of the opening side periphery of the housing, extending in the vehicle width direction and having protruding portions at both ends that protrude in the vehicle width direction beyond the distance between the pair of rear frames, with the protruding portions being fixed to the upper surfaces of the pair of rear frames, A reinforcing plate is provided integrally with the rear frame in each region where the pair of rear frames and the protruding portion are fixed, It is equipped with, The reinforcing plate is disposed in the region where the rear frame and the protruding portion are fixed, extending in the longitudinal direction of the vehicle. The reinforcing plate, the rear frame, and the battery frame are fixed together at a first fastening portion located behind the protruding portion and a second fastening portion located in front of the protruding portion. A vehicle battery unit mounting structure characterized by the following features.

2. The battery unit mounting structure for a vehicle according to claim 1, characterized in that the first fastening portion and the second fastening portion are positioned to sandwich the protruding portion in the front-rear direction of the vehicle.

3. The battery unit mounting structure for a vehicle according to claim 2, characterized in that the second fastening portion has more fastening points than the first fastening portion.

4. The vehicle battery unit mounting structure according to claim 1, characterized in that the reinforcing plate has a larger area extending forward of the vehicle than the area extending rearward of the vehicle, straddling the region where the rear frame and the protrusion are fixed.

5. The battery unit mounting structure for a vehicle according to claim 1, characterized in that the reinforcing plate is integrally joined to the rear frame by spot welding.

6. The battery frame includes at least a rear battery frame, The aforementioned protrusion is formed on the rear battery frame. The battery unit mounting structure for a vehicle according to feature 1.

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