Battery pack

Abstract

This battery pack is provided with a battery and a battery case in which the battery is accommodated. The battery case is provided with: a first frame part that extends in the left-right direction while being separated in the front-rear direction of the vehicle; a second frame part that extends in the front-rear direction while being separated in the left-right direction of the vehicle; and a cross member that spans the center portion of the second frame part.

Description

Battery pack

[0001] The present invention relates to a battery pack.

[0002] 2. Description of the Related Art In vehicles such as hybrid vehicles and electric vehicles, a battery pack for supplying electricity to a motor that serves as a drive source is provided under the luggage compartment behind the rear seats (see, for example, Patent Document 1).

[0003] JP 2018-167640 A

[0004] In the above-mentioned vehicle, it is required to protect the battery, high-voltage unit, and other components housed inside the battery pack in the event of a rear-end collision.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide suitable protection for components provided inside a battery pack.

[0006] A battery pack according to one embodiment of the present invention comprises a battery and a battery case in which the battery is housed, the battery case comprising a first frame portion extending in the left-right direction and spaced apart in the fore-and-aft direction of the vehicle, a second frame portion extending in the fore-and-aft direction and spaced apart in the left-and-aft direction of the vehicle, and a cross member spanning the central portion of the second frame portion.

[0007] According to the present invention, it is possible to suitably protect components provided inside the battery pack.

[0008] 1 is a diagram showing an outline of the configuration of a vehicle. 2 is a diagram showing an example of how a battery pack is installed. 3 is a diagram showing the configuration of the battery pack. 4 is a top view of the lower case. 5 is a diagram showing a battery and a high-voltage unit housed in the lower case. 6 is a bottom view of the lower case. 7 is an exploded view of the battery cover. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 3. 9 is a cross-sectional view taken along line IX-IX in FIG. 3. 10 is a diagram showing the configuration of a vehicle body. 11 is a diagram showing a vehicle body equipped with a battery pack. 12 is a diagram showing a vehicle body equipped with a battery pack with the cover removed. 13 is a diagram showing the transmission of load in the battery pack during a side collision. 14 is a vertical cross-sectional view taken along the longitudinal direction of the battery. 15 is a diagram showing deformation of the left frame and flange during a side collision. 16 is a diagram showing the shape of the left frame and flange at a position facing the suspension support portion. 17 is a diagram showing the shape of the flange at a position facing the suspension support portion. 18 is a diagram showing deformation of the left frame and flange at a position facing the suspension support portion during a side collision.

[0009] 1. General Configuration of Vehicle> Fig. 1 is a diagram showing the general configuration of a vehicle 1. As shown in Fig. 1, the vehicle 1 is an electric vehicle or a hybrid vehicle equipped with a motor generator 2 (denoted as "M / G" in the figure) as a power source. The vehicle 1 includes the motor generator 2, a battery pack 3, an inverter 4, and a power transmission cable 5. The battery pack 3 includes a battery 11 and a high-voltage unit 12.

[0010] The motor generator 2 is a power source, such as a three-phase AC motor, that drives the vehicle 1. The motor generator 2 generates driving force using electricity (power) supplied from the battery 11 via the high-voltage unit 12, the inverter 4, and the power transmission cable 5, and transmits the driving force to the drive wheels to drive the vehicle 1. If the vehicle 1 is a hybrid vehicle, it will also be equipped with an engine as a power source.

[0011] The motor generator 2 is capable of generating electricity (power) by performing regenerative operation. The electricity generated by the regenerative operation of the motor generator 2 is supplied to the battery 11 via the inverter 4, the power transmission cable 5, and the high-voltage unit 12.

[0012] The inverter 4 converts the DC current supplied from the battery 11 into three-phase AC current and supplies it to the motor generator 2 via the power transmission cable 5. When the motor generator 2 performs regenerative operation, the inverter 4 converts the AC current supplied from the motor generator 2 into DC current and supplies it to the battery 11 via the power transmission cable 5.

[0013] The battery 11 is a so-called high-voltage secondary battery that stores electricity to be supplied to the motor generator 2. The battery 11 can be charged by regenerative operation of the motor generator 2. The battery 11 may also be charged by electricity supplied from an external device (not shown).

[0014] The high-voltage unit 12 includes a junction box and a monitoring unit. The junction box is provided with electronic components such as relays, fuses, and connectors. The monitoring unit is provided with electronic components such as sensors for monitoring the state of the battery 11. In the vehicle 1, a BCU (Battery Control Unit), which is a computer for controlling the operation of the battery 11, is provided separately from the battery pack 3, but the BCU may be included in the high-voltage unit 12.

[0015] The high voltage unit 12 is connected to the battery 11 via a cable (not shown). Therefore, the high voltage from the battery 11 is applied to the high voltage unit 12.

[0016] Fig. 2 is a diagram showing an example of installation of the battery pack 3. As shown in Fig. 2, the vehicle 1 is provided with a luggage compartment 7 behind the rear seats 6. The luggage compartment 7 can be opened and closed by a back door 8.

[0017] A battery pack 3 is mounted below the luggage compartment 7. A luggage compartment board 9 is provided above the battery pack 3, and luggage and the like can be placed on the luggage compartment board 9.

[0018] 2. Battery Pack Configuration Fig. 3 is a diagram showing the configuration of the battery pack 3. Fig. 4 is a top view of the lower case 14. Fig. 5 is a diagram showing the battery 11 and high-voltage unit 12 housed in the lower case 14. Fig. 6 is a bottom view of the lower case 14. Fig. 7 is an exploded view of the battery case cover 15. Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 3. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 3.

[0019] In the following description, the forward direction of the vehicle 1 will be referred to as the forward direction, the backward direction of the vehicle 1 as the backward direction, the direction facing right with respect to the forward direction of the vehicle 1 as the right direction, the direction facing left with respect to the forward direction of the vehicle 1 as the left direction, the vertically upward direction as the upward direction, and the vertically downward direction as the downward direction. The left-right direction may also be referred to as the width direction of the vehicle 1 or simply as the width direction.

[0020] 3 , the battery pack 3 includes a battery case 13. The battery 11 and the high-voltage unit 12 are housed inside the battery case 13. The battery case 13 is composed of a lower case 14 that is recessed and opens upward, and a battery case cover 15 that closes the opening of the lower case 14.

[0021] As shown in Figures 3 to 6, the lower case 14 includes a front frame 21, a rear frame 22, a left frame 23, a right frame 24, a battery case pan 25, a center frame 26, a stay 27, a left front bracket 28, a right front bracket 29, a left side bracket 30, a right side bracket 31, a center frame lower 32, a left side frame lower 33, a right side frame lower 34, a crash box 35, a front frame lower 36, and a rear frame lower 37.

[0022] The front frame 21 extends in the left-right direction. As shown in Figure 8, the front frame 21 is formed so that the cross section perpendicular to the longitudinal direction is generally in an inverted U shape, opening downward. In other words, the cross section of the front frame 21 is hat-shaped. The front frame 21 is formed with fastening holes 38a, 38b, 38c, and 38d for fixing the battery pack 3 to the vehicle body.

[0023] A front bracket 17 is fastened to the front surface of the front frame 21. The front bracket 17 is attached so as to extend downward and forward from the front wall surface of the front frame 21. Two through holes are formed on the front side of the front bracket 17, and when the battery pack 3 is attached to the vehicle body 100 (see FIG. 10 ), the front bracket 17 is fastened to the front cross member 103 by fastening parts (e.g., bolts and nuts) via the through holes.

[0024] The rear frame 22 is located rearward of the front frame 21 and is arranged parallel to and spaced apart from the front frame 21 in the front-to-rear direction. Note that "parallel" includes not only completely parallel but also approximately parallel, and this also applies hereinafter. Like the front frame 21, the rear frame 22 extends in the left-to-right direction and has a cross section perpendicular to the longitudinal direction that is approximately inverted U-shaped (hat-shaped). Fastening holes 38e, 38f, 38g, and 38h are formed in the rear frame 22 for fixing the battery pack 3 to the vehicle body.

[0025] The left frame 23 extends in the front-to-rear direction. As shown in Figure 9, the left frame 23 is formed so that a cross section perpendicular to the longitudinal direction is generally in an inverted U shape, opening downward. In other words, the left frame 23 has a hat-shaped cross section. A fastening hole 39a is formed in the left frame 23 rearward of the center in the front-to-rear direction. The fastening hole 39a is formed in a position facing a fastening hole 45a of a left bracket 45 (described later), and the fastening hole 39a and the fastening hole 45a are fastened together by a fastening portion 47a.

[0026] The right frame 24 is disposed to the right of the left frame 23 and is spaced apart from and parallel to the left frame 23 in the left-right direction. Like the left frame 23, the right frame 24 extends in the front-to-rear direction and has a generally inverted U-shaped (hat-shaped) cross section. A fastening hole 39b is formed in the right frame 24 rearward of the center in the front-to-rear direction. The fastening hole 39b is formed in a position facing a fastening hole 46a of a right bracket 46 (described later), and the fastening hole 39b and the fastening hole 46a are fastened together by a fastening portion 48a. The fastening portions 47a, 48a are, for example, bolts and nuts.

[0027] The upper end of the left frame 23 is joined to the left end of the front frame 21. The upper end of the right frame 24 is joined to the right end of the front frame 21. The lower end of the left frame 23 is joined to the left end of the rear frame 22. The lower end of the right frame 24 is joined to the right end of the rear frame 22. As a result, the front frame 21, rear frame 22, left frame 23, and right frame 24 are formed as a substantially rectangular frame as a whole. Furthermore, the front frame 21, rear frame 22, left frame 23, and right frame 24 have hat-shaped cross sections, which increases their rigidity.

[0028] 8 and 9, the battery case pan 25 is formed by bending a single plate material to form a bottom surface 25a, and a front wall 25b, a rear wall 25c, a left side wall 25d, and a right side wall 25e that surround the bottom surface 25a. The bottom surface 25a, the front wall 25b, the rear wall 25c, the left side wall 25d, and the right side wall 25e form the battery case pan 25 in a recessed shape that is open at the top.

[0029] The bottom portion 25a is formed in a generally rectangular shape and extends horizontally (front-to-back and left-to-right directions). A front wall 25b is formed continuously with the upper end of the bottom portion 25a. The front wall 25b is formed so as to extend in the up-down and left-to-right directions. A rear wall 25c is formed continuously with the lower end of the bottom portion 25a. The rear wall 25c is formed so as to extend in the up-down and left-to-right directions. A left side wall 25d is formed continuously with the left end of the bottom portion 25a. The left side wall 25d is formed so as to extend in the up-down and front-to-back directions. A right side wall 25e is formed continuously with the right end of the bottom portion 25a. The right side wall 25e is formed so as to extend in the up-down and front-to-back directions. The battery case pan 25 may be formed by combining the bottom portion 25a, front wall 25b, rear wall 25c, left side wall 25d, and right side wall 25e, each made of a different plate material, by welding or the like.

[0030] The front wall 25b, rear wall 25c, left side wall 25d, and right side wall 25e each have a flange 25f formed continuously at the upper end thereof so as to extend outward. That is, the battery case pan 25 has the flange 25f formed on its outer edge. The flange 25f extends horizontally (in the front-to-rear and left-to-right directions). The front frame 21, rear frame 22, left frame 23, and right frame 24 are joined to the flange 25f from above.

[0031] The center frame 26 is joined to the upper surface of the bottom surface 25a of the battery case pan 25 so as to be centered in the left-right direction of the battery case pan 25 and aligned along the front-rear direction. As shown in Fig. 8 , the rear end of the center frame 26 abuts against the rear side wall 25c, and the front end extends forward from the center in the front-rear direction of the bottom surface 25a. As shown in Fig. 9 , the cross section of the center frame 26 perpendicular to the longitudinal direction is formed in an inverted U-shape (hat-shape), thereby increasing the rigidity of the center frame 26.

[0032] The stay 27 is joined to the upper surface of the bottom portion 25a at the center in the left-right direction of the battery case pan 25 so as to overlap the front end of the center frame 26. The front end of the stay 27 abuts the front side wall 25b and extends obliquely upward from the rear to the front. The stay 27 has an inverted U-shape (hat shape) perpendicular to the longitudinal direction, which increases its rigidity.

[0033] The left front bracket 28 is joined to the left front of the upper surface of the bottom surface portion 25a. The left front bracket 28 is made of a bent plate material so that the center portion is positioned substantially horizontal and higher than the upper surface of the bottom surface portion 25a. As shown in FIG. 5, the high-voltage unit 12 is attached to the center portion of the left front bracket 28.

[0034] The right front bracket 29 is joined to the right front of the upper surface of the bottom surface portion 25a. The right front bracket 29 is made of a bent plate material so that its center is positioned substantially horizontal and higher than the upper surface of the bottom surface portion 25a. As shown in FIG. 5, the high-voltage unit 12 is attached to the center of the right front bracket 29.

[0035] In this way, the high-voltage unit 12 is attached separately to the left front bracket 28 and the right front bracket 29. However, the high-voltage unit 12 may be attached collectively to only one of the left front bracket 28 and the right front bracket 29.

[0036] The left side bracket 30 is joined to the left rear of the upper surface of the bottom portion 25a. The left side bracket 30 is arranged to extend in the front-to-rear direction, and is made of a bent plate material so that its central portion is higher than the upper surface of the bottom portion 25a and is generally horizontal. The right side bracket 31 is joined to the right rear of the upper surface of the bottom portion 25a. The right side bracket 31 is arranged to extend in the front-to-rear direction, and is made of a bent plate material so that its central portion is higher than the upper surface of the battery case pan 25 and is generally horizontal. As shown in FIG. 9 , the battery 11 is attached so as to span the center of the left side bracket 30 and the right side bracket 31. Note that the illustration shows an example in which two stacks of multiple cells are provided as the battery 11.

[0037] As shown in Fig. 6, the center frame lower 32 extends in the front-rear direction at the center of the battery case pan 25 in the left-right direction and is joined to the underside of the bottom surface 25a. The left side frame lower 33 and the right side frame lower 34 are arranged parallel to the left and right of the center frame lower 32, extend in the front-rear direction, and are joined to the underside of the bottom surface 25a. As shown in Fig. 9, the center frame lower 32, the left side frame lower 33, and the right side frame lower 34 have a U-shaped (inverted hat) cross section perpendicular to the longitudinal direction, which increases their rigidity.

[0038] In this way, the rigidity of the upper part of the lower case 14 is increased by the front frame 21, rear frame 22, left frame 23, and right frame 24. In addition, the rigidity of the lower part of the lower case 14 is increased by the center frame 26, stays 27, center frame lower 32, left side frame lower 33, and right side frame lower 34.

[0039] The lower case 14 also prevents the battery case pan 25 from being crushed by external forces from the left and right direction by the front frame 21 and rear frame 22. Furthermore, the lower case 14 also prevents the battery case pan 25 from being crushed by external forces from the front and rear direction by the left frame 23, right frame 24, center frame 26, stays 27, center frame lower 32, left side frame lower 33, and right side frame lower 34.

[0040] The crash boxes 35 are joined from below to the central rear end of the bottom surface 25a so as to overlap the rear ends of the center frame lower 32, left side frame lower 33, and right side frame lower 34. As shown in FIG. 8 , the crash boxes 35 are composed of two plates 35a, 35b, and a separator member 35c. The front end of the plate 35a is joined to the vertical center of the rear wall 25c and extends downward and rearward from its front end to its rear end. The tip of the plate 35b is joined to the bottom surface 25a and the rear end of the center frame lower 32 and extends upward and rearward from its front end to its rear end. The separator member 35c has a structure including two separators connecting the plate members 35a and 35b, which are spaced apart in the vertical direction. The crash box 35 is formed by plate members 35a and 35b so that the cross section perpendicular to the left-right direction has a closed cross section (approximately rectangular), and its interior is reinforced by a separator member 35c to increase its strength.

[0041] 8, the front frame lower 36 is joined from below to the front flange 25f of the battery case pan 25. As a result, the front flange 25f of the battery case pan 25 is sandwiched between the front frame 21 and the front frame lower 36, further increasing the rigidity of the front portion of the lower case 14.

[0042] The rear frame lower 37 is joined from below to the rear flange 25f of the battery case pan 25. As a result, in the battery case pan 25, the rear flange 25f is sandwiched between the rear frame 22 and the rear frame lower 37, further increasing the rigidity of the rear portion of the lower case 14.

[0043] As shown in FIGS. 3 and 7, the battery case cover 15 includes a main cover 41, a left front cover 42, a service plug cover 43, a right front cover 44, a left bracket 45, and a right bracket 46.

[0044] The main cover 41 includes a lower cover 51, a center frame upper 52, a first cover cross member 53, and a second cover cross member 54.

[0045] The lower cover 51 is formed in a shape such that the front left and front right portions are cut out of a substantially rectangular plate material. The length of the lower cover 51 in the front-to-rear direction is approximately the same as the distance between the front frame 21 and the rear frame 22 of the lower case 14, and the length of the lower cover 51 in the left-to-right direction is approximately the same as the distance between the left frame 23 and the right frame 24 of the lower case 14.

[0046] A through-hole 51a is formed in the lower cover 51 below the second cover cross member 54. A cooling duct (not shown) is connected to the through-hole 51a. The cooling duct is a duct for sending air from the vehicle interior into the battery case 13, and the air is sent into the battery case 13 by a fan (not shown).

[0047] A through hole 51b is formed in the lower cover 51 between the first cover cross member 53 and the second cover cross member 54. An exhaust duct 16 is connected to the through hole 51b. One end of the exhaust duct 16 is connected to the through hole 51b, and the other end is open to the outside of the vehicle. The exhaust duct 16 is provided to exhaust smoke outside the vehicle when the battery 11 emits smoke.

[0048] The upper center frame 52 is joined to the top surface of the lower cover 51 at the center in the left-right direction of the lower cover 51 so as to extend in the front-rear direction. The upper center frame 52 is formed so that its length in the front-rear direction is approximately the same as that of the lower cover 51. As shown in FIG. 8 , the upper center frame 52 spans between the front frame 21 and the rear frame 22.

[0049] The first cover cross member 53 is joined to the upper surface of the lower cover 51 so as to extend in the left-right direction near the center of the lower cover 51 in the front-rear direction. The first cover cross member 53 is formed so that its length in the left-right direction is approximately the same as that of the lower cover 51.

[0050] The second cover cross member 54 is joined to the upper surface of the lower cover 51 so as to be disposed parallel to and spaced apart from the first cover cross member 53 in the front-to-rear direction. The second cover cross member 54 is disposed rearward of the first cover cross member 53. Like the first cover cross member 53, the second cover cross member 54 is formed so that its length in the left-to-right direction is approximately the same as that of the lower cover 51.

[0051] As shown in Figure 9, the first cover cross member 53 and the second cover cross member 54 are bridged between the left frame 23 and the right frame 24. In addition, as shown in Figure 8, the first cover cross member 53 and the second cover cross member 54 are disposed directly above the battery 11.

[0052] The center frame upper 52, the first cover cross member 53 and the second cover cross member 54 have a cross section perpendicular to the longitudinal direction that is formed in a generally inverted U-shape (hat-shape), thereby increasing rigidity.

[0053] The first cover cross member 53 and the second cover cross member 54 have a thickness in the vertical direction greater than that of the center frame upper 52. Therefore, the first cover cross member 53 and the second cover cross member 54 are joined to the lower cover 51 so as to pass above the center frame upper 52.

[0054] The left front cover 42 is formed from a plate material in a generally rectangular shape so as to fit into the upper left notch of the lower cover 51. A through hole 42a is formed in the left front cover 42 at a position facing the service plug of the high-voltage unit 12 provided in the battery case 13. A service plug cover 43 is attached to cover the through hole 42a from above. The service plug cover 43 is formed from a plate material and is detachable from the left front cover 42.

[0055] The right front cover 44 is made of a plate material and is formed into a substantially rectangular shape so as to fit into the upper right notch of the lower cover 51 .

[0056] The left front cover 42 and the right front cover 44 are fastened to the lower cover 51 and the upper center frame 52 by fastening parts (e.g., bolts and nuts). This gives the battery case cover 15 a generally rectangular shape as a whole. The battery case cover 15 is then fastened to the front frame 21, rear frame 22, left frame 23, and right frame 24 of the lower case 14 by fastening parts.

[0057] The left bracket 45 and the right bracket 46 are made of plate material and are formed into a generally triangular shape in top view. Fastening holes 45a, 45b, and 45c are formed in the left bracket 45 at positions corresponding to the corners of the generally triangle. Fastening holes 46a, 46b, and 46c are formed in the right bracket 46 at positions corresponding to the corners of the generally triangle.

[0058] The main cover 41 has a fastening hole 41a formed in a position facing the fastening hole 45b, and a fastening hole 41b formed in a position facing the fastening hole 46b. The left bracket 45 has the fastening hole 45a fastened to the fastening hole 39a of the left frame 23 by the fastening portion 47a, and the fastening hole 45b fastened to the fastening hole 41a of the main cover 41 by the fastening portion 47b. This fixes the left bracket 45 to the left frame 23 and the main cover 41. The right bracket 46 has the fastening hole 46a fastened to the fastening hole 39b of the right frame 24 by the fastening portion 48a, and the fastening hole 46b fastened to the fastening hole 41b of the main cover 41 by the fastening portion 48b. This fixes the right bracket 46 to the right frame 24 and the main cover 41.

[0059] The left bracket 45 and the right bracket 46 are not essential components, and may not be provided.

[0060] 3. Vehicle Body Configuration Next, a description will be given of the configuration of a vehicle body on which the battery pack 3 is mounted. It is assumed that the battery pack 3 will be mounted on a plurality of different vehicle bodies. Therefore, an example of a vehicle body on which the battery pack 3 is mounted will be described here.

[0061] Fig. 10 is a diagram showing the configuration of the vehicle body 100. Fig. 11 is a diagram showing the vehicle body 100 equipped with the battery pack 3. Fig. 12 is a diagram showing the vehicle body 100 equipped with the battery pack 3 with the battery case cover 15 removed.

[0062] 10, 11, and 12, the vehicle body 100 includes a left main frame 101 and a right main frame 102. The left main frame 101 and the right main frame 102 are spaced apart in the left-right direction and extend along the front-rear direction.

[0063] A front cross member 103 and a rear cross member 104 are spanned between the left main frame 101 and the right main frame 102. The front cross member 103 and the rear cross member 104 are joined to the left main frame 101 and the right main frame 102 so as to be spaced apart in the front-to-rear direction and extend in the left-to-right direction. The front cross member 103 is disposed near the boundary between the rear seat 6 and the luggage compartment 7 in the front-to-rear direction. The rear cross member 104 is disposed approximately in the center of the luggage compartment 7 in the front-to-rear direction. The front cross member 103 has a cross section perpendicular to the longitudinal direction that is formed as a hollow, approximately rectangular, closed cross section, thereby enhancing its rigidity. The rear cross member 104 has a cross section perpendicular to the longitudinal direction that is formed as a hollow, approximately rectangular, closed cross section, thereby enhancing its rigidity.

[0064] A floor pan 105 is mounted between the left main frame 101 and the right main frame 102. The floor pan 105 is formed by bending a plate material into a concave shape that opens upward. A flange is formed on the outer edge of the floor pan 105, and the left main frame 101, the right main frame 102, and the front cross member 103 are joined to this flange. The rear cross member 104 is joined to the underside of the floor pan 105.

[0065] A left gusset 106 is joined to the joint between the left main frame 101 and the front cross member 103, reinforcing the joint between the left main frame 101 and the front cross member 103. Similarly, a right gusset 107 is joined to the joint between the right main frame 102 and the front cross member 103, reinforcing the joint between the right main frame 102 and the front cross member 103.

[0066] A suspension support member 108, to which a suspension abuts, is joined to the left main frame 101 forward of the rear cross member 104 in the front-to-rear direction. The suspension support member 108 is disposed so as to protrude leftward from the left main frame 101. The suspension support member 108 is also disposed so as to tilt upward as it extends leftward.

[0067] A suspension support member 109, to which the suspension abuts, is joined to the right main frame 102 forward of the rear cross member 104 in the front-to-rear direction. The suspension support member 109 is disposed so as to protrude to the right from the right main frame 102. The suspension support member 109 is also disposed so as to tilt upward as it extends to the right.

[0068] A rear skirt 110 is joined to the rear end of the floor pan 105. The rear skirt 110 is disposed so as to extend upward from the floor pan 105. A striker is attached to the center of the rear skirt 110 in the left-right direction, and the luggage compartment 7 is closed when the back door 8 engages with the striker.

[0069] A rear bumper beam 111 is joined to the rear ends of the left main frame 101 and the right main frame 102. The rear bumper beam 111 is arranged to extend in the left-right direction, with both ends joined to the left main frame 101 and the right main frame 102, respectively. Most of the rear bumper beam 111 is arranged rearward and spaced apart from the left main frame 101, the right main frame 102, the floor pan 105, and the rear skirt 110. The rear bumper beam 111 has greater strength than other components constituting the vehicle body 100, and reduces damage to the vehicle body 100 in a rear-end collision (including an offset collision).

[0070] In the vehicle body 100, the battery pack 3 is fastened to the left main frame 101, the right main frame 102, and the front cross member 103. When the battery pack 3 is fastened to the vehicle body 100, the left bracket 45 and the right bracket 46 are not provided on the battery pack 3 (they are removed).

[0071] The front cross member 103 (left gusset 106, right gusset 107) has fastening holes 112a, 112b spaced apart in the left-right direction on the left side and fastening holes 112c, 112d spaced apart in the left-right direction on the right side. The left main frame 101 has fastening holes 112e, 112f spaced apart in the front-rear direction on the rear side. The right main frame 102 has fastening holes 112g, 112h spaced apart in the front-rear direction on the rear side. These fastening holes 112a to 112h are located at positions corresponding to the fastening holes 38a to 38h formed in the battery pack 3, respectively.

[0072] Fastening hole 112a and fastening hole 38a are fastened together by fastening portion 113a. Similarly, fastening hole 112b and fastening hole 112h and fastening hole 38b and fastening hole 38h are fastened together by fastening portions 113b and 113h, respectively. Fastening portions 113e and 113g are formed by threads and nuts welded to extend upward from the top surfaces of left main frame 101 and right main frame 102. Fastening portions 113a, 113b, 113c, 113d, 113f, and 113h are formed by bolts and nuts, for example. Note that hereinafter, when fastening portions 113a to 113h are described without distinction, they will be referred to as fastening portions 113.

[0073] 4. Battery Protection Structure Fig. 13 is a diagram showing the transfer of load during a side collision in the battery pack 3. In Fig. 13, the transfer of load is indicated by black arrows.

[0074] If the vehicle 1 is hit by an object from the side (for example, from the left), if the front frame 21, rear frame 22, left frame 23, and right frame 24 alone attempt to absorb the load of the collision from the side (hereinafter referred to as the side collision load), the left frame 23 or the right frame 24 may bend or deform, which could damage the battery 11 and high-voltage unit 12.

[0075] Therefore, the battery pack 3 is provided with a first cover cross member 53 and a second cover cross member 54. As described above, the first cover cross member 53 and the second cover cross member 54 are bridged across and fastened to the central portions of the left frame 23 and the right frame 24. Therefore, when a side collision load is applied to the left frame 23, the side collision load is transmitted not only to the front frame 21 and the rear frame 22 but also to the first cover cross member 53 and the second cover cross member 54.

[0076] At this time, the first cover cross member 53 and the second cover cross member 54 brace the central portions of the left frame 23 and the right frame 24, thereby reducing bending of the left frame 23 and the right frame 24 at their central portions, thereby reducing damage to the battery 11 and the high-voltage unit 12 caused by bending of the left frame 23 and the right frame 24 at their central portions.

[0077] In particular, the first cover cross member 53 and the second cover cross member 54 are disposed vertically above the batteries 11. Specifically, the batteries 11 are disposed along the left-right direction. The first cover cross member 53 is disposed vertically above and along the front battery 11 of the two batteries 11. Similarly, the second cover cross member 54 is disposed vertically above and along the rear battery 11 of the two batteries 11.

[0078] As a result, the first cover cross member 53 and the second cover cross member 54 can prevent bending of the portions of the left frame 23 and the right frame 24 that face the battery 11 in the front-to-rear direction.

[0079] 14 is a vertical cross-sectional view taken along the longitudinal direction of the battery 11. The left side of the battery 11 will be mainly described below, but the same applies to the right side.

[0080] In order to extend the driving distance and improve fuel economy of the vehicle 1, a larger capacity (larger size) battery 11 is required. Therefore, as shown in Fig. 14, the battery 11 is arranged close to, for example, the left side wall 25d of the battery case pan 25. Therefore, not much clearance is provided between the battery 11 and the left side wall 25d.

[0081] In such a case, if the left frame 23 is bent by the side collision load, it will immediately come into contact with the battery 11. For this reason, it is particularly effective to provide the first cover cross member 53 and the second cover cross member 54.

[0082] A flange 23b extending leftward (outward) and expanding horizontally is connected to the lower end of the left side wall 23a of the left frame 23. A flange 25f of the battery case pan 25 is joined to the lower part of the left frame 23.

[0083] If the flanges 23b and 25f extend straight in the horizontal direction, a side collision load will be input to the flanges 23b and 25f in the battery pack 3. In this case, the left frame 23 and the flange 25f will maintain their original shapes without changing, and the side collision load may cause the left frame 23 to move to the right. This may cause the left frame 23 to come into contact with the battery 11, damaging the battery 11.

[0084] Therefore, a step 25g (crank) is formed on the flange 25f at a position facing the left frame 23, more specifically at a position that forms a closed cross section together with the left frame 23. In other words, the step 25g is formed on the flange 25f so that the height varies in the vertical direction (so that the left side is higher) as it extends leftward (outward).

[0085] 15 is a diagram showing deformation of the left frame 23 and flange 25f during a side collision. When the vehicle 1 is hit from the left side and a side collision load is applied to the battery pack 3, the side collision load is input to the flange 23b of the left frame 23 and the flange 25f of the battery case pan 25. This side collision load is transmitted to the step 25g of the flange 25f.

[0086] 15, the flange 25f is deformed to form an upward convex shape at the step 25g. In addition, as the battery case pan 25 is deformed, the left frame 23 is bent inward around the connection between the left side wall 23a and the top surface 23c.

[0087] This makes it possible to prevent the left frame 23 from moving to the right due to a side collision load, thereby reducing contact of the left frame 23 with the battery 11.

[0088] Fig. 16 is a diagram showing the shapes of the left frame 23 and the flange 25f at a position facing the suspension support member 108. Fig. 17 is a diagram showing the shape of the flange 25f at a position facing the suspension support member 108.

[0089] As described above, the suspension support member 108 is disposed so as to tilt upward as it moves toward the left. Therefore, the portion of the battery pack 3 that faces the suspension support member 108 is formed so that the suspension support member 108 does not come into contact with the portion.

[0090] 16, the left frame 23 has a left side wall 23a that is shorter than the other portions as a shape of the portion facing the suspension support member 108. Also, the left frame 23 has a flange 23b that extends in an upper left direction.

[0091] The flange 25f of the battery case pan 25 is formed so that the portion facing the suspension support member 108 extends in an upper left direction. As shown in FIG. 17 , a bead 25h extending in the left-right direction is formed on the flange 25f at the portion facing the suspension support member 108. The bead 25h is formed from the left end toward the inside to a predetermined length. Here, the left-right length of the bead 25h is shorter than the left-right length of the plane of the flange 25f.

[0092] 18 is a diagram showing deformation of the left frame 23 and the flange 25f during a side collision at a position facing the suspension support member 108. When the vehicle 1 is side-collided from the left side and a side collision load is applied to the battery pack 3, as shown in FIG. 18, the flange 23b of the left frame 23 and the flange 25f of the battery case pan 25 extend in an upper left direction, so that the flange 23b bends upward (clockwise in the drawing) around the connection between the flange 23b and the left side wall 23a. Furthermore, as the flange 23b of the battery case pan 25 deforms, the flange 25f bends upward.

[0093] This makes it possible to prevent the left frame 23 from moving to the right due to a side collision load, thereby preventing the left frame 23 from coming into contact with the battery 11. In this case, if a bead 25h is formed on the flange 25f, this is effective because it can promote bending of the flange 25f.

[0094] 5. Modifications The above embodiment is merely an example of how the present invention can be implemented, and the implementation of the present invention is not limited to the above example, and various modifications are possible.

[0095] In the above description, the battery pack 3 is provided with two cross members, the first cover cross member 53 and the second cover cross member 54. However, the battery pack 3 may be provided with one cross member or three or more cross members.

[0096] In the above embodiment, two batteries 11 are provided. However, one battery 11 or three or more batteries 11 may be provided.

[0097] 6. Summary As described above, the battery pack 3 of the embodiment includes the battery 11 and the battery case 13 that houses the battery 11. The battery case 13 includes first frame portions (corresponding to the front frame 21 and the rear frame 22) that extend in the left-right direction and are spaced apart in the front-rear direction of the vehicle, second frame portions (corresponding to the left frame 23 and the right frame 24) that extend in the front-rear direction and are spaced apart in the left-right direction of the vehicle, and cross members (corresponding to the first cover cross member 53 and the second cover cross member 54) that span across central portions of the second frame portions. As a result, when a side collision load is transmitted to the battery pack 3, the first cover cross member 53 and the second cover cross member 54 brace central portions of the left frame 23 and the right frame 24, thereby reducing bending of the left frame 23 and the right frame 24 at their central portions. This reduces damage to the battery 11 and the high-voltage unit 12 that would be caused by bending of the left frame 23 and the right frame 24 at their central portions.

[0098] The battery 11 is disposed along the left-right direction, and the cross members are disposed vertically above the battery 11. This allows the first cover cross member 53 and the second cover cross member 54 to further suppress deformation of the portions of the left frame 23 and the right frame 24 that face the battery 11.

[0099] The battery pack 3 includes a battery case pan 25 joined to the first and second frame portions and housing the battery 11. The battery case pan 25 has an outwardly extending flange 25f formed on its outer edge. The second frame portion has a hat-shaped cross section perpendicular to the longitudinal direction and is joined to the flange 25f of the battery case pan 25 from below. A step 25g is formed on the flange 25f of the battery case pan 25 at a position facing the second frame portion. This causes the flange 25f to deform into an upwardly convex shape at the step 25g due to a side collision load. Furthermore, as the battery case pan 25 deforms, the left frame 23 bends inward around the connection between the left side wall 23a and the top surface 23c. This prevents the left frame 23 from moving rightward due to a side collision load, reducing contact of the left frame 23 with the battery 11.

[0100] The battery pack 3 includes a battery case pan 25 joined to the first and second frame portions and housing the battery 11. The battery case pan 25 has a flange 25f extending outward from its outer edge. The second frame portion has a hat-shaped cross section perpendicular to the longitudinal direction and is joined to the flange 25f of the battery case pan 25 from below. The flange 25f extends upward as it extends outward. This allows the flange 25f of the battery case pan 25 to bend upward due to a side collision load. The left frame 23 also bends in response to deformation of the flange 25f. This makes it possible to prevent the left frame 23 from moving rightward due to a side collision load, thereby preventing the left frame 23 from coming into contact with the battery 11.

[0101] REFERENCE SIGNS LIST 1 vehicle 3 battery pack 11 battery 21 front frame 22 rear frame 23 left frame 24 right frame 53 first cross member 54 second cross member

Claims

1. A battery pack comprising: a battery; and a battery case in which the battery is housed, wherein the battery case comprises: a first frame portion extending in the left-right direction and spaced apart in the front-to-rear direction of the vehicle; a second frame portion extending in the front-to-rear direction and spaced apart in the left-to-right direction of the vehicle; and a cross member spanning a central portion of the second frame portion.

2. The battery pack according to claim 1, wherein the battery is arranged along the left-right direction, and the cross member is arranged vertically above the battery.

3. A battery pack as claimed in claim 1 or claim 2, comprising a battery case pan joined to the first frame portion and the second frame portion and accommodating the battery, wherein the battery case pan has a flange formed on its outer edge that extends outward, the second frame portion has a hat-shaped cross section perpendicular to the longitudinal direction and is joined to the flange of the battery case pan from below, and a step is formed on the flange at a position opposite the second frame portion.

4. A battery pack as described in claim 1 or claim 2, comprising a battery case pan joined to the first frame portion and the second frame portion and accommodating the battery, wherein the battery case pan has a flange formed on its outer edge that extends outward, and the second frame portion has a hat-shaped cross section perpendicular to the longitudinal direction and is joined to the flange of the battery case pan from below, and the flange is formed so as to extend upward as it extends outward.

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