Battery Pack Protection Device

Abstract

While ensuring space inside the vehicle, it also reduces damage to the battery pack caused by obstacles on the road while driving. [Solution] A battery pack protection device that protects a battery pack 27 mounted on a vehicle, comprising a protective body 2 provided in front of the battery pack 27 and below the front axle O of the vehicle 20, and a link mechanism 5 as a variable mechanism, the protective body 2 having a base 3 fixed to the bottom of the front cross member 21, and a crushing section 4 attached below the base 3 via the link mechanism 5 so that it can move up and down, the protective body 2 lowers the position of the crushing section 4 relative to the base 3 via the link mechanism 5, and when the vehicle 20 is traveling, the crushing section 4 of the protective body 2 can crush or bounce off obstacles R on the road surface G.

Description

[Technical Field]

[0001] The present invention relates to a battery pack protection device that protects a battery pack that supplies power to a traction motor of an electric vehicle. [Background technology]

[0002] Conventionally, some electric vehicles have a battery pack that supplies power to a driving motor and is located below the floor panel. The battery pack located below the floor panel may be damaged by collision with obstacles such as stones or foreign objects on the road surface while the vehicle is traveling. To prevent damage to the battery pack, for example, Patent Document 1 discloses a battery pack in which a protective plate is located below the bottom surface of a battery case that houses multiple battery stacks.

[0003] The battery pack described in Patent Document 1 includes a cooler arranged on the bottom surface of a battery case and a cushioning member. In the cooler, a cooling module is arranged for each of a plurality of battery stacks, and a connection part is provided to connect adjacent cooling modules. A cushioning member is arranged between the protective plate and the connection part, and a weakened part is formed in the part of the connection part where the cushioning member is arranged.

[0004] In the battery pack described in Patent Document 1, when a foreign object on the road collides with the protective plate while the vehicle is traveling, the protective plate bulges upward, causing the buffer material to shrink and deform, while pressing the connection part upward. At this time, the buffer material bends starting from the weak part of the connection part, thereby absorbing the impact of the collision.

[0005] Furthermore, in order to prevent damage to the battery pack, for example, Patent Document 2 discloses a battery pack in which a plurality of first skeletal members and a plurality of second skeletal members are provided on the bottom of the battery pack case (battery case). In the battery pack described in Patent Document 2, the plurality of first skeletal members extend in the vehicle width direction and are arranged at intervals from each other in the vehicle front-rear direction. The plurality of second skeletal members extend in the vehicle front-rear direction and are arranged at intervals from each other in the vehicle width direction.

[0006] In the battery pack described in Patent Document 2, the plurality of first skeletal members and the plurality of second skeletal members can prevent the bottom of the battery case from being hit by obstacles on the road surface when the vehicle is traveling. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2023-046518 [Patent Document 2] Japanese Patent Publication No. 2020-114701 Summary of the Invention [Problem to be solved by the invention]

[0008] The battery pack described in Patent Document 1 has a space between the bottom of the battery case and the protective plate. This space must be large enough in the vertical direction so that when an obstacle on the road collides with the protective plate while the vehicle is in motion, the protective plate does not bulge upward and hit the bottom of the battery case. This space can be secured by raising the position of the battery case. However, raising the position of the battery case also raises the position of the floor panel, which can reduce the interior space of the vehicle.

[0009] The battery pack described in Patent Document 2 requires space below the battery case to accommodate multiple first skeletal members and multiple second skeletal members. This space can be secured by raising the position of the battery case. However, raising the position of the battery case also raises the position of the floor panel, which can reduce the vehicle interior space.

[0010] Therefore, an object of the present invention is to prevent damage to the battery pack caused by obstacles on the road surface while driving, while ensuring sufficient space in the vehicle interior. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention can employ the following configurations 1 to 5. [Configuration 1] A battery pack protection device for protecting a battery pack mounted in a vehicle, A battery pack protection device having a protector provided in front of the battery pack and below the front axle of the vehicle, and a variable mechanism for changing the vertical position of the bottom of the protector.

[0012] [Configuration 2] The battery pack protection device according to configuration 1 includes an operating means for operating the variable mechanism, a vehicle speed detection means for detecting the vehicle speed, and a control unit for controlling the operation of the variable mechanism based on the vehicle speed, and when the vehicle is traveling at a predetermined speed or higher, the control unit operates the variable mechanism using the operating means and controls the position of the bottom of the protector to be lowered.

[0013] [Configuration 3] The battery pack protection device according to configuration 1 has an operating means for operating the variable mechanism, a detection means for detecting the condition of the road surface, and a control unit for controlling the operation of the variable mechanism based on the condition of the road surface, and when an obstacle of a predetermined size or larger is detected on the road surface, the control unit operates the variable mechanism using the operating means and controls the position of the bottom of the protector to be lowered.

[0014] [Configuration 4] The battery pack protection device according to configuration 1 has an elastic member that biases the bottom of the protector upward, and when the protector experiences air resistance equal to or greater than a predetermined air resistance while the vehicle is traveling, the position of the bottom of the protector descends against the biasing force of the elastic member, and when the protector experiences air resistance smaller than the predetermined air resistance, the position of the bottom of the protector rises due to the biasing force of the elastic member.

[0015] [Configuration 5] 5. The battery pack protection device according to any one of configurations 1 to 4, wherein the bottom of the protector is lowered by the variable mechanism toward the battery pack at the rear in the vehicle longitudinal direction. [Effects of the Invention]

[0016] According to this invention, when the vehicle is traveling, the variable mechanism lowers the position of the bottom of the protective body in front of the battery pack, crushing or bouncing off obstacles on the road surface, thereby preventing obstacles from colliding with the bottom of the battery pack, eliminating the need to raise the position of the battery pack relative to the road surface, and ensuring space in the vehicle interior. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a side view showing a vehicle to which a battery pack protection device according to a first embodiment of the present invention is applied; [Figure 2] FIG. 1 is a bottom view showing a vehicle to which the battery pack protection device of the same is applied; [Figure 3] Cross section along line AA in Figure 2 [Figure 4] A cross-sectional view showing the state in which the crushing part of the protective body in FIG. 3 rises. [Figure 5] FIG. 1A is an explanatory diagram showing a state in which the crushable portion of the protector of the battery pack protection device rises; FIG. 1B is an explanatory diagram showing a state in which the crushable portion of the protector of the battery pack protection device falls; [Figure 6] FIG. 2 is a flowchart showing the control by the control unit of the battery pack protection device of the embodiment; [Figure 7]FIG. 10A is an explanatory diagram showing a state in which the crushable portion of the protector of the battery pack protection device according to the second embodiment of the present invention is rising; FIG. 10B is an explanatory diagram showing a state in which the crushable portion of the protector of the battery pack protection device according to the second embodiment of the present invention is falling; DETAILED DESCRIPTION OF THE INVENTION

[0018] A battery pack protection device 1 according to a first embodiment of the present invention will be described with reference to the drawings. As shown in Figures 1 to 4, the battery pack protection device 1 is applied to an electrically powered vehicle 20, such as an electric vehicle or a hybrid vehicle, equipped with a battery pack 27 that supplies power to a traction motor.

[0019] The electric vehicle 20 includes a front motor 22 and a pair of front tires 23 attached to a front cross member 21, a rear motor 25 and a pair of rear tires 26 attached to a rear cross member 24, a battery pack 27 disposed below a floor panel 30, and a battery pack protection device 1. In the following description, the up-down direction, the front-rear direction, and the vehicle width direction are based on the vehicle parked on level ground.

[0020] The front cross member 21 is attached to the front lower surfaces of a pair of front side members 28. The front cross member 21 is a frame-shaped member in a plan view. As shown in Fig. 2, the front cross member 21 has a pair of side members 21a extending in the vehicle width direction and a pair of cross members 21b extending in the front-rear direction that spans between the pair of side members 21a.

[0021] A front motor 22 is disposed between the pair of side members 21a in the vehicle width direction and between the pair of cross members 21b in the front-rear direction. Lower arms 21c are attached to both sides of the pair of side members 21a in the vehicle width direction. A pair of front tires 23 are rotatably attached to the pair of side members 21a via the lower arms 21c.

[0022] The rear cross member 24 is attached to the lower part of a pair of rear side members 29. The rear cross member 24 is a frame-shaped member in a plan view. As shown in Fig. 2, the rear cross member 24 has a pair of side members 24a extending in the vehicle width direction and a pair of cross members 24b extending in the front-rear direction that spans between the pair of side members 24a.

[0023] A rear motor 25 is disposed between the pair of side members 24a in the vehicle width direction and between the pair of cross members 24b in the front-rear direction. A pair of rear tires 26 are rotatably attached to the pair of side members 24a via lower arms 24c.

[0024] The battery pack 27 has a plurality of battery cells (not shown) that supply power to the front motor 22 and the rear motor 25, and a flat, box-shaped case 27a that houses the plurality of battery cells. Fixing pieces 27b are provided at multiple locations in the front-to-rear direction of the vehicle on both sides of the case 27a in the vehicle width direction. Each fixing piece 27b is fixed to the lower surface of a pair of front side members 28. A floor panel 30 is attached to the upper part of the battery pack 27.

[0025] The battery pack protection device 1 includes a protection body 2 attached to the lower part of the front cross member 21, a variable mechanism, an operating means for operating the variable mechanism, a detection means for detecting the condition of the road surface G in front of the electric vehicle 20, a vehicle speed detection means for detecting the vehicle speed of the electric vehicle 20, and a control unit for controlling the operation of the variable mechanism.

[0026] The protector 2 has a base 3 and a crushing unit 4 that is arranged below the base 3 via the variable mechanism. The base 3 is formed from a metal plate that is rectangular in plan view. The base 3 is fixed to the front cross member 21 with its length aligned with the vehicle width direction. The base 3 has a width dimension in the vehicle width direction that is slightly smaller than that of the battery pack 27. Two fasteners 3a are integrally provided on each of the front and rear end faces of the base 3. The two front fasteners 3a protrude forward from the front end face of the base 3. The two rear fasteners 3a protrude rearward from the rear end face of the base 3.

[0027] The fixture 3a has an upper surface portion 3b located at the upper end side and a pair of side surfaces 3c integrally formed on both sides of the upper surface portion 3b in the vehicle width direction. The upper surface of the upper surface portion 3b is located on the same plane as the upper surface of the base portion 3. The pair of side surfaces 3c are inclined downward from both ends of the upper surface portion 3b in the vehicle width direction toward the outside in the vehicle width direction and extend outward in the vehicle width direction from their lower ends. The lower surfaces of the extending portions of the pair of side surfaces 3c are located on the same plane as the lower surface of the base portion 3.

[0028] Of the two fixing devices 3a located on the front and rear sides of the base 3, the upper surface 3b of the fixing device 3a located on one side in the vehicle width direction and the cross member 21b located on one side in the vehicle width direction of the cross members 21b are fastened together with fasteners 31 consisting of bolts and nuts. Of the two fixing devices 3a located on the front and rear sides of the base 3, the upper surface 3b of the fixing device 3a located on the other side in the vehicle width direction and the cross member 21b located on the other side in the vehicle width direction are fastened together with fasteners 31 consisting of bolts and nuts.

[0029] As a result of this fastening, as shown in Fig. 2, the base 3 of the protector 2 is disposed below the axle O of the front pair of tires 23. Here, the axle O is an axis in the vehicle width direction that passes through the center of rotation of each of the front pair of tires 23. Also, as shown in Fig. 1, the base 3 is disposed within a range that does not extend beyond the circumference of the front pair of tires 23 when viewed from the side.

[0030] The crushing unit 4 is a rectangular metal plate-like member. The crushing unit 4 is attached below the base 3 via the variable mechanism so that it can be raised and lowered, with the length of the crushing unit 4 aligned with the vehicle width direction. The crushing unit 4 has the same width dimensions in the vehicle width direction and the vehicle front-rear direction as the base 3.

[0031] As shown in Figures 5(a) and 5(b), a link mechanism 5 is used as the variable mechanism. The link mechanism 5 is a parallel link mechanism having a pair of link members 5a. The link mechanism 5 is arranged on both sides of the base 3 and the crushing unit 4 in the vehicle width direction. One end of the pair of link members 5a in the length direction is rotatably attached to the outer end surface of the base 3 in the vehicle width direction. The other end of the pair of link members 5a in the length direction is rotatably attached to the outer end surface of the crushing unit 4 in the vehicle width direction. The pair of link members 5a are inclined so as to face downward toward the front in the vehicle longitudinal direction.

[0032] The apparatus has an operating means for operating the link mechanism 5. As the operating means, a hydraulic or electric actuator can be used. In this embodiment, an electric actuator 32 is used as the operating means. As shown in FIGS. 5(a) and 5(b), the electric actuator 32 includes an electric motor 32a attached to the base 3 and a slide shaft 32b whose tip is attached to the crushing unit 4. When driven by the electric motor 32a, the electric actuator 32 converts the rotational force of the electric motor 32a into linear motion using a ball screw mechanism (not shown), thereby moving the slide shaft 32b forward and backward, thereby operating the link mechanism 5.

[0033] The control unit that controls the operation of the link mechanism 5 is, for example, a control unit (not shown) that controls the operation of various electronic devices provided in the electric vehicle 20. As detection means that detects the state of the road surface G ahead of the electric vehicle 20, for example, a sensor camera (not shown) that captures image information around the electric vehicle 20 is used. As vehicle speed detection means that detects the traveling speed (vehicle speed) of the electric vehicle 20, for example, a vehicle speed sensor that detects the vehicle speed provided in the electric vehicle 20 is used.

[0034] The flow of control of the elevation of the crushing unit 4 of the protective body 2 by the control unit will be described with reference to the flow chart of FIG. First, in step S1, it is determined whether the driver has started up the vehicle system and the vehicle is in a ready state (READY state). This start-up operation is, for example, an operation in which the driver presses a start button (power switch) provided near the driver's seat. If it is determined in step S1 that the vehicle is in the READY state, the process proceeds to step S2.

[0035] In step S2, it is determined whether the vehicle speed of the electric vehicle 20 is equal to or greater than a predetermined speed. If the vehicle speed sensor determines in step S2 that the vehicle speed is equal to or greater than the predetermined speed, the process proceeds to step S3. If the detection means determines in step S3 that the obstacle R on the road surface G is equal to or greater than a predetermined size, the process proceeds to step S4. In step S4, the link mechanism 5 is operated by the operating means (electric actuator 32), and control is performed to lower the crushing unit 4 of the protective body 2. After step S4, the process returns to step S1.

[0036] If it is determined in step S2 that the vehicle speed is less than a predetermined speed, or if it is determined in step S3 by the detection means that the obstacle is smaller than a predetermined size, the process proceeds to step S5. In step S5, the link mechanism 5 is operated by the electric actuator 32, and control is performed to raise the crushing section 4 of the protective body 2. After step S5, the process returns to step S1.

[0037] If it is determined in step S1 that the device is not in the READY state, the process proceeds to step S6. In step S6, the link mechanism 5 is operated by the electric actuator 32 to raise the crushing unit 4 of the protective body 2, and the control of the control unit ends in step S7.

[0038] In this embodiment, when the control unit determines that the vehicle speed of the electric vehicle 20 is equal to or greater than a predetermined speed, or when it determines that an obstacle on the road surface is equal to or greater than a predetermined size, the control unit may operate the link mechanism 5 using the electric actuator 32 and control the lowering of the crushing section 4 of the protective body 2.

[0039] In a battery pack protection device 1 according to an embodiment of the present invention, a protector 2 includes a base 3 attached to a front cross member 21, and a crushing unit 4 that rises and falls below the base 3 via a link mechanism 5. In this embodiment, when a control unit determines that the vehicle speed of an electric vehicle 20 is equal to or greater than a predetermined speed and that an obstacle on the road surface is equal to or greater than a predetermined size, the control unit activates the link mechanism 5 and controls the lowering of the crushing unit 4 of the protector 2. When the crushing unit 4 of the protector 2 is lowered, the bottom surface of the crushing unit 4 is lower than the bottom surface of the battery pack 27, as shown in FIG. 1 . Therefore, when the electric vehicle 20 is traveling, obstacles R, such as stones or foreign objects, on the road surface G are bounced off or crushed by the crushing unit 4.

[0040] The size of the crushed obstacles R becomes smaller and they are less likely to collide with the bottom surface of the battery pack 27, thereby reducing damage to the battery pack 27. As a result, it is no longer necessary to raise the position of the battery pack 27 in order to reduce damage to the battery pack 27, as in the past, and space in the vehicle interior can be secured.

[0041] Also, since there is no need to raise the position of battery pack 27, it is possible to ensure the height from the road surface G to the bottom surface of battery pack 27 (height above ground), and to lower the center of gravity of battery pack 27. Furthermore, since there is no need to provide a protective plate or the like at the bottom of the battery pack as in the past, it is possible to reduce the weight and cost of battery pack 27.

[0042] In the battery pack protection device 1 of this embodiment, the control unit activates the link mechanism 5 and controls the raising of the crushing unit 4 of the protective body 2 when the vehicle speed of the electric vehicle 20 is below a predetermined speed. When the vehicle speed of the electric vehicle 20 is below a predetermined speed, the driver can visually recognize an obstacle R on the road surface G and take action to avoid it. Therefore, as described above, only when the vehicle speed of the electric vehicle 20 is above a predetermined speed and it is difficult for the driver to take action to avoid an obstacle R on the road surface G, the control unit can activate the link mechanism 5 and control the lowering of the crushing unit 4 of the protective body 2.

[0043] Furthermore, in the battery pack protection device 1 of this embodiment, when the detection means determines that the obstacle R on the road surface G is smaller than a predetermined size, the control unit activates the link mechanism 5 and controls the raising of the crushing unit 4 of the protector 2. When the obstacle R on the road surface G is smaller than the predetermined size, for example, when the crushing unit 4 is raised and the height of the obstacle R on the road surface G is smaller than the height from the road surface G to the crushing unit 4, there is no risk of the obstacle R damaging the battery pack 27. Therefore, only when the obstacle R on the road surface G is larger than the predetermined size and there is a risk of the obstacle R damaging the battery pack 27, the control unit can activate the link mechanism 5 and control the lowering of the crushing unit 4 of the protector 2.

[0044] In the battery pack protection device 1 of this embodiment, the protector 2 is provided in front of the battery pack 27 and below the front axle O of the electric vehicle 20. The crushing section 4 of the protector 2 is lowered by a link mechanism 5 relative to the base 3 toward the battery pack 27 at the rear in the longitudinal direction of the vehicle. Therefore, when an obstacle R on the road surface G is bounced outward in the vehicle width direction by the base 3 or the crushing section 4 while the electric vehicle 20 is traveling, the bounced obstacle R hits the front pair of tires 23. This prevents the obstacle R from being bounced onto a sidewalk or the like located around the electric vehicle 20 and outward in the vehicle width direction.

[0045] Next, a battery pack protection device 11 according to a second embodiment of the present invention will be described with reference to Fig. 7. This battery pack protection device 11 differs from the battery pack protection device 1 according to the first embodiment described above in that the actuating means for actuating the link mechanism 5 is an elastic member, and that the device does not include a control unit for controlling the actuation of the link mechanism 5. Since the other components are the same as those in the first embodiment, the same reference numerals as those in the first embodiment are used and their description will be omitted.

[0046] As shown in FIG. 7(a), in a battery pack protection device 11, a coil spring 12 serving as the elastic member is stretched between a base 3 and a crushable portion 4 of a protector 2. One end (upper end) of the coil spring 12 is attached to the base 3, and the other end (lower end) of the coil spring 12 is attached to the crushable portion 4. When the crushable portion 4 is in contact with the base 3, the coil spring 12 is stretched relative to its natural state and stretched between the base 3 and the crushable portion 4. The natural state of the coil spring 12 refers to a state in which no external force is acting on the coil spring 12 and the coil spring 12 is not stretched. The coil spring 12 biases the crushable portion 4 upward.

[0047] The crushing unit 4 is biased upward by the coil spring 12. Therefore, when the electric vehicle 20 is traveling, the crushing unit 4 experiences air resistance that corresponds to the speed of the electric vehicle 20. For example, as the speed of the electric vehicle 20 increases, the crushing unit 4 may experience air resistance that exceeds a predetermined level. In the battery pack protection device 11 of this embodiment, when the crushing unit 4 experiences air resistance that exceeds the predetermined level, the crushing unit 4 descends via the link mechanism 5 against the biasing force of the coil spring 12, lowering the position of the bottom of the crushing unit 4 (see FIG. 7(b)). This allows the crushing unit 4 to bounce off or crush obstacles R on the road surface G, preventing damage to the battery pack 27 that may occur when the obstacles R on the road surface G get caught below the battery pack 27.

[0048] Furthermore, when the vehicle speed of the electric vehicle 20 decreases and the crushing unit 4 experiences air resistance smaller than a predetermined air resistance, the crushing unit 4 rises due to the biasing force of the coil spring 12, raising the position of the bottom of the crushing unit 4. When the vehicle speed of the electric vehicle 20 decreases to the point where the crushing unit 4 rises, the driver can visually recognize and take evasive action against an obstacle on the road surface. Therefore, as described above, the crushing unit 4 descends and the position of the bottom of the crushing unit 4 can be lowered only when the vehicle speed of the electric vehicle 20 increases and it is difficult for the driver to take evasive action against an obstacle R on the road surface G.

[0049] In this embodiment, the configuration of the present invention has been explained assuming an electric vehicle (electric vehicle (EV)) that has only a front motor 22 and a rear motor 25 as a driving source for driving, but the present invention can also be applied to hybrid vehicles (HVs) that have a motor and an engine as a driving source for driving, in particular plug-in hybrid vehicles (PHEVs) that can externally charge the onboard secondary battery from an external charging facility and can also externally supply power from the secondary battery to external devices, and fuel cell vehicles (FCEVs) that have a hydrogen tank or the like for storing hydrogen as fuel and a fuel cell below the floor panel. [Explanation of symbols]

[0050] 1, 11 Battery pack protection device 2 Protective Body 3 base 4 Crushing section 5 Link mechanism 5a Link member 12 Coil spring 20 Electric Vehicles 21 Front cross member 21a, 24a Side members 21b, 24b cross members 21c, 24c lower arm 22 Front motor 23, 26 tires 24 Rear cross member 25 rear motor 27 Battery Pack 28 Front side member 29 Rear side member 30 Floor Panel 31 Fasteners 32 Electric Actuator 32a Electric motor 32b Slide shaft O Axle G road surface R Obstacle

Claims

1. A battery pack protection device for protecting a battery pack mounted in a vehicle, A battery pack protection device having a protector provided in front of the battery pack and below the front axle of the vehicle, and a variable mechanism for changing the vertical position of the bottom of the protector.

2. 2. The battery pack protection device according to claim 1, further comprising: an operating means for operating the variable mechanism; a vehicle speed detection means for detecting the vehicle speed; and a control unit for controlling the operation of the variable mechanism based on the vehicle speed, wherein when the vehicle is traveling at a predetermined speed or above, the control unit operates the variable mechanism using the operating means and controls the position of the bottom of the protection body to be lowered.

3. 2. The battery pack protection device according to claim 1, further comprising: an operating means for operating the variable mechanism; a detection means for detecting the condition of the road surface; and a control unit for controlling the operation of the variable mechanism based on the condition of the road surface, wherein when an obstacle of a predetermined size or larger is detected on the road surface, the control unit operates the variable mechanism using the operating means and controls the position of the bottom of the protector to be lowered.

4. 2. The battery pack protection device according to claim 1, further comprising an elastic member that biases the bottom of the protective body upward, and when the protective body experiences air resistance equal to or greater than a predetermined air resistance while the vehicle is traveling, the position of the bottom of the protective body descends against the biasing force of the elastic member, and when the protective body experiences air resistance smaller than the predetermined air resistance, the position of the bottom of the protective body rises due to the biasing force of the elastic member.

5. 5. The battery pack protection device according to claim 1, wherein the bottom of the protection body is lowered by the variable mechanism toward the battery pack at the rear in the vehicle longitudinal direction.

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