Patent Publication Number: US-8540282-B2

Title: Protecting structure for power source apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a protecting structure in which a power source apparatus mounted on a vehicle is surrounded by a plurality of frames to protect the power source apparatus against shocks from the outside. 
     BACKGROUND ART 
     Secondary batteries have conventionally been mounted on vehicles such that the output from the secondary battery is used to run the vehicle or the secondary battery is charged with regenerative energy from the vehicle (for example, see Patent Documents 1 and 2). In such a vehicle, it is necessary to suppress the application of an excessive load to the secondary battery to prevent damage to the secondary battery when the vehicle is subjected to an external force in a collision. 
     To address this, in Patent Document 1, a floor panel is formed to be easy-to-deform to absorb shocks so that no external force may act on a battery. In Patent Document 2, a bracket connected to a battery pack has a rotatable configuration and the bracket is rotated to absorb a shock when a vehicle is subjected to the shock.
     Patent Document 1: Japanese Patent Laid-Open No. 2001-113959 (Paragraph No. 0013)   Patent Document 2: Japanese Patent Laid-Open No. 2007-253933 (FIGS. 1, 7, and 8)   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     Patent Document 1, however, discloses the configuration in which the battery is merely fixed to the floor panel. An external force may act on the battery depending on the magnitude of the external force applied to a vehicle. On the other hand, Patent Document 2 discloses the configuration in which the battery pack is fixed to a floor panel by using bolts. An external force may act on the battery pack depending on the magnitude of the external force applied to the vehicle. 
     It is thus an object of the present invention to provide a protecting structure for a power source apparatus capable of suppressing the action of an external force on the power source apparatus when a vehicle is subjected to a shock. 
     Means for Solving the Problems 
     According to the present invention, a protecting structure for a power source apparatus comprises a frame unit in which a plurality of frames are connected to each other and surround the power source apparatus mounted on a vehicle; and an abutting member extending in a direction in which an external force in a predetermined direction acts on the vehicle, one end thereof connected to the frame unit, and the other end thereof being away from the vehicle body, wherein the abutting member is displaced in the predetermined direction in response to displacement of the frame unit subjected to the external force in the predetermined direction and the other end of the abutting member abuts on the vehicle body. 
     The frame unit can be fixed to the vehicle body through a fixing member. According to the protecting structure of the present invention, it is possible to absorb an external force by abutting the abutting member on the vehicle body. Therefore it is not necessary to strengthen fixing of the fixing member. Specifically, the structure of the fixing member can be simplified. 
     The power source apparatus can be placed in a rearward position of the vehicle. In addition, the power source apparatus can be formed of a secondary battery. Specifically, the power source apparatus comprises an assembled battery having a plurality of cells (secondary battery) and a case housing the assembled battery. The vehicle body on which the abutting member abuts is a cross member extending in a direction from left to right of the vehicle. 
     According to another aspect, the present invention provides a frame unit in which a plurality of frames are connected to each other and surround a power source apparatus mounted on a vehicle, wherein, of the plurality of frames, a frame placed along a lower surface of the power source apparatus is formed integrally with a frame placed along a side face of the power source apparatus. 
     According to another aspect, the present invention provides a frame unit in which a plurality of frames are connected to each other and surround a power source apparatus mounted on a vehicle, wherein the plurality of frames include two frames placed along side faces of the power source apparatus and extending in directions orthogonal to each other. One of the two frames has a projection portion which abuts on the other frame to prevent deformation of the frame. 
     Effect of the Invention 
     According to the present invention, the frame unit formed of the plurality of frames is used to surround the power source apparatus, so that when an external force is applied to the vehicle, the direct action of the external force on the power source apparatus can be suppressed. In addition, since the abutting member extending in the direction in which the abutting member abuts on the vehicle body is connected to the frame unit, the external force applied to the frame unit can be conveyed to the vehicle body through the abutting member. This can suppress the action of the external force on the power source apparatus through the frame unit. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  A perspective view of the outer appearance showing the configuration of a portion of a vehicle in Embodiment 1 of the present invention. 
         FIG. 2  A schematic diagram showing the configuration of a battery pack. 
         FIG. 3  A perspective view of the outer appearance showing the configuration of a protecting frame in Embodiment 1. 
         FIG. 4  A top view showing the configuration of a portion of the protecting frame in Embodiment 1. 
         FIG. 5  A side view showing the configuration of the protecting frame in Embodiment 1. 
         FIG. 6  A side view showing the configuration of a protecting frame in Embodiment 2 of the present invention. 
         FIG. 7  A side view showing the configuration of a protecting frame in a comparative example of Embodiment 2. 
         FIG. 8  A side view showing the configuration of a protecting frame in Embodiment 3 of the present invention. 
         FIG. 9  A side view showing the configuration of a protecting frame in Embodiment 4 of the present invention. 
     
    
    
     EMBODIMENT OF THE INVENTION 
     Preferred embodiments of the present invention will hereinafter be described. 
     Embodiment 1 
     A vehicle in Embodiment 1 of the present invention will be described with reference to  FIG. 1 .  FIG. 1  is a perspective view of the outer appearance showing the configuration of a portion of the vehicle in the present embodiment. In  FIG. 1 , an X axis, a Y axis, and a Z axis are axes orthogonal to each other. The X axis corresponds to a traveling direction of the vehicle. The traveling direction refers to a direction in which the vehicle runs forward and backward. The Y axis corresponds to a transverse direction of the vehicle, and the Z axis corresponds to a direction of gravity. 
     The vehicle in the present embodiment is a vehicle on which a battery pack (power source apparatus) is mounted. Examples of the vehicle include a hybrid vehicle and an electric vehicle. The hybrid vehicle is a vehicle which has not only the battery pack but also another power source such as an internal combustion engine or a fuel battery which outputs energy for use in running of the vehicle. The electric vehicle is a vehicle which runs only with the output from the battery pack. The battery pack in the present embodiment is discharged to output energy for use in running of the vehicle or is charged with energy produced in braking of the vehicle or with power supplied from the outside of the vehicle. 
     A vehicle body  1  has a pair of side members  10  extending in the X direction, a cross member  12  extending in the Y direction and connected to the pair of side members  10 , and a floor panel  11  fixed to the pair of side members  10 . The side members  10  and the cross member  12  constitute the skeleton of the vehicle body  1 . 
     The floor panel  11  has a housing portion  11   a  formed therein for housing a spare tire. The housing portion  11   a  can be omitted. A protecting frame (protecting structure)  20  is placed above the housing portion  11   a  of the floor panel  11 . The protecting frame  20  is provided for protecting the battery pack mounted on the vehicle. Specifically, the protecting frame  20  has a structure which surrounds the periphery of the battery pack to prevent the direct action of an external force on the battery pack. 
     The specific configuration of the protecting frame  20  will be described later. As shown in  FIG. 1 , the protecting frame  20  is placed in a rearward position of the vehicle body  1 . For example, the protecting frame  20  (battery pack) can be placed in a luggage room of the vehicle. 
     As shown in  FIG. 2 , the battery pack  30  has an assembled battery  31  and a case  32  for housing the assembled battery  31 . The assembled battery  31  is fixed to the case  32  by fastening members such as bolts, and the case  32  is fixed to the protecting frame  20  through fastening members such as bolts. The assembled battery  31  is formed of a plurality of cells connected electrically in series through a bus bar. A secondary battery such as a nickel metal hydride battery or a lithium-ion battery can be used as the cell. Instead of the secondary battery, an electric double layer capacitor (capacitor) can be used. 
     The cell may have any shape, and for example, a cylindrical type or a square type can be used. It is possible to supply a gas for adjusting the temperature of the assembled battery  31  into the case  32 . Specifically, a gas for cooling can be supplied to suppress a rise in temperature of the assembled battery  31 . In addition, a gas for heating can be supplied to suppress a drop in temperature of the assembled battery  31 . A fluid can be housed in the case  32  instead of the gas. Specifically, an insulating fluid can be housed to promote heat transfer between the assembled battery  31  and the case  32 . As the insulating fluid, an insulating oil or a fluorochemical inert fluid can be used. 
     As shown in  FIG. 1 , the protecting frame  20  is fixed to the side members  10  and the floor panel  11  through a plurality of fixing members  13 ,  14 , and  15 . 
     A pair of first fixing members  13  is connected to the portion of the protecting frame  20  that is located in a rearward position of the vehicle. The first fixing members  13  are fixed to the associated side members  10  by fastening members such as bolts. A pair of second fixing members  14  and a pair of third fixing members  15  are connected to the portions of the protecting frame  20  that are located in a forward position of the vehicle. The second fixing members  14  are fixed to the associated side members  10  by fastening members such as bolts. The third fixing members  15  are located between the pair of second fixing members  14  in the Y direction and are fixed to the floor panel  11  by fastening members such as bolts. 
     Next, the configuration of the protecting member  20  will be described with reference to  FIGS. 3 and 4 .  FIG. 3  is a perspective view showing the outer appearance of the protecting frame  20 .  FIG. 4  is a diagram illustrating the protecting frame  20  viewed from the top (Z direction) and showing the configuration of a portion of the protecting frame  20 . 
     A first frame  21   a  is located on a rearward side of the vehicle and extends in the Y direction. A second frame  21   b  is located in the direction of gravity (downward direction) relative to the first frame  21   a  and extends in the Y direction. The first frame  21   a  and the second frame  21   b  are placed generally in parallel within a Y-Z plane. The lengths of the first frame  21   a  and the second frame  21   b  in the Y direction are larger than the length of the battery pack  30  in the Y direction. The first fixing members  13  are connected to both ends of the second frame  21   b.    
     Four third frames  21   c  extending in the Z direction are connected to the first frame  21   a  and the second frame  21   b . The third frame  21   c  has a length larger than that of the battery pack  30  in the Z direction. The four third frames  21   c  are placed at equal intervals in the Y direction. While the four third frames  21   c  are provided in the present embodiment, the present invention is not limited thereto. The number of the third frames  21   c  and the interval between the third frames  21   c  can be set as appropriate. Specifically, the number and the like of the third frames  21   c  can be set in view of the strength and the like of the protecting frame  20 . 
     A fourth frame  21   d  is located in a forward position of the vehicle and extends in the Y direction. In contrast to the other frames, the fourth frame  21   d  has a triangular shape in section orthogonal to a longitudinal direction of the fourth frame  21   d . A fifth frame  21   e  is located in the direction of gravity (downward direction) relative to the fourth frame  21   d  and extends in the Y direction. The second fixing members  14  are connected to both ends of the fifth frame  21   e . The third fixing members  15  are connected to central portions of the fifth frame  21   e.    
     The lengths of the fourth frame  21   d  and the fifth frame  21   e  in the Y direction are larger than the length of the battery pack  30  in the Y direction. Four sixth frames  21   f  are connected to the fourth frame  21   d  and the fifth frame  21   e . The sixth frames  21   f  extend in the Z direction such that they are inclined with respect to the Y-Z plane. Specifically, the end portions of the sixth frames  21   f  that are connected to the fifth frames  21   e  are located forward of the vehicle with respect to the end portions of the sixth frames  21   f  that are connected to the fourth frames  21   d . The four sixth frames  21   f  are placed at equal intervals in the Y direction. 
     While the sixth frames  21   f  are inclined with respect to the Y-Z plane in the present embodiment, the present invention is not limited thereto. Specifically, the sixth frames  21   f  can be placed along the Z direction similarly to the third frames  21   c . While the four sixth frames  21   f  are provided in the present embodiment, the present invention is not limited thereto. The number of the sixth frames  21   f  and the interval between the sixth frames  21   f  can be set as appropriate. Specifically, the number and the like of the sixth frames  21   f  can be set in view of the strength and the like of the protecting frame  20 . 
     Five seventh frames  21   g  extending in the X direction are connected to the first frame  21   a  and the fourth frame  21   d . The first frame  21   a , the fourth frame  21   d , and the seventh frames  21   g  are located in the same plane (in an X-Y plane) and constitute an upper plane of the protecting frame  20 . The number of the seventh frames  21   g  and the interval between the seventh frames  21   g  can be set as appropriate. 
     Four eighth frames  21   h  extending in the X direction are connected to the second frame  21   b  and the fifth frame  21   e . The second frame  21   b , the fifth frame  21   e , and the eighth frames  21   h  are located in the same plane (in the X-Y plane) and constitute a lower plane of the protecting frame  20 . The interval between the upper plane and the lower plane of the protecting frame  20  is larger than the length of the battery pack  30  in the Z direction. The lengths of the eighth frames  21   h  and the seventh frames  21   g  in the X direction are larger than the length of the battery pack  30  in the X direction. The number of the eighth frames  21   h  and the interval between the eighth frames  21   h  can be set as appropriate. 
     Abutting frames (abutting members)  22  extending toward the cross member  12  are connected to both ends of the second frame  21   b . The abutting frames  22  and the four eighth frames  21   h  are located in the same plane (in the X-Y plane), and the abutting frames  22  are placed such that they are inclined with respect to the eighth frames  21   h . As shown in  FIG. 4 , the abutting frames  22  are placed in a rearward position of the vehicle relative to the cross member  12 , and a portion of the cross member  12  and the abutting frames  22  are located in the same plane (in the X-Y plane). 
     An area of each of the abutting frames  22  closer to its end is connected to the eighth frame  21   h  through a support frame  23 . The support frame  23  is provided for supporting the area of the abutting frame  22  closer to the end. The support frame  23  can be omitted. 
     Protruding portions  12   a  protruding in the Z direction are formed at both end portions of the cross members  12 . The protruding portion  12   a  has a surface opposed to an end portion  22   a  of the abutting frame  22 . A predetermined clearance is provided between the protruding portion  12   a  and the end portion  22   a  of the abutting frame  22 . The clearance is provided for preventing interference between the end portion  22   a  of the abutting frame  22  and the protruding portion  12   a  of the cross member  12  in mounting the protecting frame  20  on the vehicle body  1 . 
     The frames  21   a  to  21   h ,  22 , and  23  constituting the protecting frame  20  can be connected to each other by welding or can be connected by using fastening members such as bolts. 
     Next, the functions of the protecting frame  20  of the present embodiment will be described with reference to  FIG. 5 .  FIG. 5  is a side view showing the configuration of the protecting frame  20 . 
     When an excessive load (external force) is applied to a rearward portion of the vehicle in a collision or the like of the vehicle, the portion of the floor panel  11  that is located in a rearward position of the vehicle is deformed. Such deformation of the floor panel  11  can absorb the external force. The external force is also applied to the protecting frame  20  depending on the degree of the deformation of the floor panel  11 . In  FIG. 5 , an arrow represents the external force F acting on the protecting frame  20 . 
     For example, when the external force F exceeds the yield point of the first fixing members  13 , the protecting frame  20  is displaced in the direction in which the external force F acts, so that the end portion  22   a  of the abutting frame  22  abuts on the protruding portion  12   a  of the cross member  12 . This causes the external force F acting on the protecting frame  20  to be transferred to the cross member  12  through the abutting frame  22 . Since the cross member  12  is subjected to the external force F through the abutting frame  22 , the cross member  12  is deformed to absorb the external force F. 
     The cross member  12  is a member constituting part of the skeleton of the vehicle body  1 , and thus the external force F transferred to the cross member  12  through the abutting frame  22  is converted into force which will run the vehicle forward. The forward running of the vehicle can absorb the external force F. 
     It is contemplated that the connecting portion between the protecting frame  20  and the vehicle body  1  can have a robust structure in order to prevent detachment of the protecting frame  20  from the vehicle body  1  due to the external force F acting on the protecting frame  20 . In this case, however, the number of parts used in the connecting portion is increased. A configuration in which the protecting frame  20  and the vehicle body  1  are merely fixed mechanically to each other has a limit to the external force F, and the protecting frame  20  may be detached from the vehicle body  1  depending on the magnitude of the external force F. 
     Since the battery pack  30  is surrounded by the protecting frame  20  in the present embodiment, the direct action of the external force on the battery pack  30  can be suppressed even when the vehicle is subjected to a shock. Specifically, the external force reaches the protecting frame  20  before it reaches the battery pack  30 , so that the application of an excessive load to the battery pack  30  can be prevented. 
     Alternatively, the battery pack  30  can be reinforced to ensure the strength of the battery pack  30 . The use of the configuration of the protecting frame  20  in the present embodiment, however, can result in a simpler configuration. Specifically, if the battery pack  30  is reinforced, a complicated reinforcement structure should be used, but the protecting frame  20  in the present embodiment can be realized with a simpler structure since it is provided by simply combining the plurality of frames. 
     In the present embodiment, the external force F acting on the protecting frame  20  is transferred to the cross member  12  through the abutting frame  22  to absorb the external force F as described above. This can achieve the simple structure for fixing the protecting frame  20  to the vehicle body  1  to prevent an increase in cost of the fixing structure of the protecting frame  20  to the vehicle body  1 . 
     In the present embodiment, when the external force F acts on the protecting frame  20 , the end portion  22   a  of the abutting frame  22  abuts on the cross member  12  before the first fixing member  13  is detached from the side member  10 . Thus, the external force F can be conveyed to the cross member  12  in a relatively early stage after the external force F acts on the protecting frame  20 , thereby allowing a reduction in load on the protecting frame  20 . 
     The present embodiment can readily provide the above-mentioned effects when the battery pack  30  is increased in size. Specifically, when the battery pack  30  is increased in size, the protecting frame  20  is located close to a rearward portion of the vehicle. The battery pack  30  is increased in size when a plurality of assembled batteries  31  are used or when the number of cells constituting the assembled battery  31  is increased. 
     In such a case, the external force applied to the vehicle tends to act on the protecting frame  20 . Thus, the protecting frame  20  in the present embodiment can be used to convey the external force applied to the protecting frame  20  efficiently to the cross member  12  through the abutting frame  22 . 
     While the end portion  22   a  of the abutting frame  22  is caused to abut on the cross member  12  in the present embodiment, the present invention is not limited thereto. Specifically, when the end portion  22   a  of the abutting frame  22  is caused to abut on a member which constitutes part of the skeleton of the vehicle body  1 , the same effects as those in the present embodiment can be provided. Examples of the member which constitutes part of the skeleton of the vehicle body  1  include not only the cross member  12  but also a reinforcement member (gusset) serving as a reinforcement in connecting the frames of the vehicle, for example. 
     While the abutting frames  22  are connected to the second frame  21   b  in the present embodiment, the present invention is not limited thereto. For example, the abutting frames  22  can be connected to the third frames  21   c . In this case, the external force F applied to the protecting frame  20  can also be transferred to the cross member  12  through the abutting frames  22 . In addition, it is essential only that the abutting frames  22  should extend toward the protruding portions  12   a  of the cross member  12 , and the specific shape of the abutting frames  22  can be set as appropriate. Specifically, while each of the abutting frames  22  has a hollow shape in the present embodiment, another shape can be used. 
     Embodiment 2 
     A vehicle in Embodiment 2 of the present invention will be described with reference to  FIG. 6 .  FIG. 6  is a side view showing the configuration of a protecting frame in the present embodiment. In the present embodiment, members having the same functions as those described in Embodiment 1 are designated with the same reference numerals, and detailed description thereof is omitted. In the following, different points from those in Embodiment 1 will be described. 
     While the protecting frame  20  of Embodiment 1 has the abutting frames  22  which abut on the cross member  12 , the abutting frames  22  and the support frames  23  are not provided in the present embodiment. 
     In a protecting frame  20  of the present embodiment, a connecting member  24  extending along a first frame  21   a  is fixed to a side face of the first frame  21   a . A seventh frame  21   g  is fixed to the first frame  21   a  by welding. 
     A connecting member  25  which is to be connected to the connecting member  24  is fixed to an end of each of third frames  21   c . The connecting members  24  and  25  are connected to each other by fastening members such as bolts to fix the first frame  21   a  to the third frame  21   c .  FIG. 6  shows the state before the first frame  21   a  is fixed to the third frame  21   c . For fixing the first frame  21   a  to the third frame  21   c , the first frame  21   a  is moved in a direction indicated by an arrow A. 
     The third frame  21   c  is formed integrally with an eighth frame  21   h . For example, the third frame  21   c  and the eighth frame  21   h  can be formed integrally by molding, or the third frame  21   c  and the eighth frame  21   h  can be formed integrally by welding. The third frame  21   c  of the present embodiment is different from the third frame  21   c  described in Embodiment 1. Specifically, while the third frame  21   c  is connected to the second frame  21   b  extending in the Y direction in Embodiment 1, the third frame  21   c  is connected to the eighth frame  21   h  in the present embodiment. In addition, a fixing member  13  is provided in a corner portion of the frame in which the third frame  21   c  and the eighth frame  21   h  are formed integrally. 
     The plurality of third frames  21   c  are placed in a Y direction in the present embodiment, and a frame is provided between the adjacent ones of the third frames  21   c  in the Y direction for connection of the third frames  21   c . The frame extends in the Y direction similarly to the second frame  21   b  described in Embodiment 1. 
     Since the third frame  21   c  and the eighth frame  21   h  are formed integrally in the present embodiment, the deformation of the third frame  21   c  can be suppressed even when an external force F is applied to the protecting frame  20 . 
     It is contemplated that the protecting frame  20  has the configuration shown in  FIG. 7 . In this case, however, the third frame  21   c  is deformed and applies an excessive load to a battery pack  30  when the protecting frame  20  is subjected to an external force F. In the following, the configuration shown in  FIG. 7  will be described specifically. 
     In the configuration shown in  FIG. 7 , one end of the third frame  21   c  is fixed to the first frame  21   a , and a connecting member  26  is provided at the other end of the third frame  21   c . A connecting member  27  which is to be connected to the connecting member  26  is provided for the second frame  21   b . The connecting members  26  and  27  have flange portions  26   a  and  27   a  opposite to each other in a Z direction, respectively. 
     The flange portions  26   a  and  27   a  are connected to each other by fastening members such as bolts to fix the third frame  21   c  to the second frame  21   b .  FIG. 7  shows the state before the third frame  21   c  is fixed to the second frame  21   b . For fixing the third frame  21   c  to the second frame  21   b , the third frame  21   c  is moved in a direction indicated by an arrow A. 
     In the configuration of the protecting frame  20  shown in  FIG. 7 , the third frame  21   c  may be deformed as shown by dotted lines in  FIG. 7  when the external force F is applied. When the third frame  21   c  is deformed as shown by the dotted lines in  FIG. 7 , the end portion of the third frame  21   c  applies an excessive load to the battery pack  30 . Since the third frame  21   c  and the second frame  21   b  are fixed to each other only by the connection of the connecting members  26  and  27 , the third frame  21   c  is easily detached from the second frame  21   b  unless the connecting portion of the connecting members  26  and  27  has greater rigidity. 
     On the other hand, in the configuration of the present embodiment shown in  FIG. 6 , the third frame  21   c  and the eighth frame  21   h  are formed integrally, and the end portion of the third frame  21   c  is placed adjacent to the side face of the first frame  21   a  with the connecting member  24  interposed between them. Thus, even when the third frame  21   c  is subjected to the external force F, the deformation of the end portion of the third frame  21   c  as shown by the dotted lines in  FIG. 7  can be prevented. This can improve the strength of the protecting frame  20  against shocks from the rear of the vehicle. 
     While the abutting frames  22  and the support frames  23  described in Embodiment 1 are not provided in the present embodiment, the abutting frames  22  and the support frames  23  can be provided similarly to Embodiment 1. This can efficiently suppress the application of an excessive load to the battery pack  30 . 
     Embodiment 3 
     A vehicle in Embodiment 3 of the present invention will be described with reference to  FIG. 8 .  FIG. 8  is a side view showing the configuration of a protecting frame in the present embodiment. In the present embodiment, the configuration of the protecting frame is changed from that in Embodiment 1. Members having the same functions as those described in Embodiment 1 are designated with the same reference numerals. 
     While the protecting frame  20  in Embodiment 1 has the abutting frames  22  which abut on the cross member  12 , the abutting frames  22  and the support frames  23  are not provided in the present embodiment. 
     In a protecting frame  20  of the present embodiment, a third frame  21   c  is fixed to a side face of a first frame  21   a  by welding or the like. A connecting member  26  is attached to an end portion of the third frame  21   c  and a depression portion  21   c   1  is formed in the end portion. 
     A connecting member  27  is attached to a side face of a second frame  21   b . The connecting member  27  is connected to the connecting member  26  by fastening members such as bolts. Specifically, flange portions  26   a  and  27   a  provided for the connecting members  26  and  27 , respectively, are connected to each other by fastening members such as bolts to fix the third frame  21   c  to the second frame  21   b.    
     A projection portion  21   b   1  which is to be inserted into the depression portion  21   c   1  of the third frame  21   c  is formed integrally with the side face of the second frame  21   b  that is opposed to the end portion of the third frame  21   c . In the present embodiment, the third frame  21   c  is moved toward the second frame  21   b  in a direction indicated by an arrow A to insert the projection portion  21   b   1  into the depression portion  21   c   1  of the third frame  21   c  and the connecting members  26  and  27  are fixed by fastening members to constitute the protecting frame  20 . In the present embodiment, the strength of the protecting frame  20  is ensured by the engagement of the projection portion  21   b   1  and the depression portion  21   c   1  and the connection of the connecting members  26  and  27 . 
     In the present embodiment, the strength of the protecting frame  20  can be improved as compared with the configuration shown in  FIG. 7 . Even when the protecting frame  20  is subjected to an external force F, the deformation of the third frame  21   c  as shown by the dotted lines in  FIG. 7  can be prevented. In addition, in the present embodiment, the abutment of the projection portion  21   b   1  on the depression portion  21   c   1  can enhance the strength in the connecting portion of the third frame  21   c  and the second frame  21   b . This can achieve a simple configuration of the connecting members  26  and  27 . Specifically, it is essential only that the connecting structure of the connecting members  26  and  27  should be formed such that the projection portion  21   b   1  is not be detached from the depression portion  21   c   1 . 
     While the present embodiment has the configuration in which the projection portion  21   b   1  is inserted into the depression portion  21   c   1 , the present invention is not limited thereto. For example, the projection portion  21   b   1  can be in contact with the side face of the third frame  21   c  that is opposed to the battery pack  30 . In this case, the position of the projection portion  21   b   1  is different from that in the configuration shown in  FIG. 8 . In this configuration, when the protecting frame  20  is subjected to the external force F, the abutment of the side face of the third frame  21   c  on the projection portion  21   b   1  can also suppress the deformation of the end portion of the third frame  21   c.    
     While the abutting frames  22  and the support frames  23  described in Embodiment 1 are not provided in the present embodiment, the abutting frames  22  and the support frames  23  can be provided similarly to Embodiment 1. This can efficiently suppress the application of an excessive load to the battery pack  30 . 
     While the depression portion  21   c   1  is provided for the third frame  21   c  and the projection portion  21   b   1  is provided for the second frame  21   b  in the present embodiment, the present invention is not limited thereto. Specifically, a projection portion corresponding to the projection portion  21   b   1  can be provided for the third frame  21   c , and a depression portion corresponding to the depression portion  21   c   1  can be provided for the second frame  21   b.    
     Embodiment 4 
     A vehicle in Embodiment 4 of the present invention will be described with reference to  FIG. 9 .  FIG. 9  is a side view showing the configuration of a protecting frame in the present embodiment. In the present embodiment, members having the same functions as those described in Embodiments 1 and 2 are designated with the same reference numerals, and detailed description thereof is omitted. In the following, different points from those in Embodiments 1 and 2 will be described. 
     While the protecting frame  20  in Embodiment 1 has the abutting frames  22  which abut on the cross member  12 , the abutting frames  22  and the support frames  23  are not provided in the present embodiment. In addition, while the protecting frame  20  in Embodiment 1 has the third frames  21   c  provided on the upper surface of the second frame  21   b , a side face of a third frame  21   c  is connected to a side face of a second frame  21   b  in the present embodiment. A fixing member  13  is provided for an end portion of the third frame  21   c.    
     In the protecting frame  20  of the present embodiment, the deformation of end portion of the third frame  21   c  can be suppressed even when an external force F is applied. One end portion of the third frame  21   c  is connected to a first frame  21   a  extending in a Y direction, while the other end portion of the third frame  21   c  is connected to the second frame  21   b  extending in the Y direction. Thus, both end portions of the third frame  21   c  are prevented from being deformed by the first frame  21   a  and the second frame  21   b . This can enhance the strength of the protecting frame  20 . 
     While the abutting frames  22  and the support frames  23  described in Embodiment 1 are not provided in the present embodiment, the abutting frames  22  and the support frames  23  can be provided similarly to Embodiment 1. This can efficiently suppress the application of an excessive load to the battery pack  30 .