Patent Publication Number: US-11383590-B2

Title: Vehicle underfloor battery connector protector structure

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2018-157717 filed on Aug. 24, 2018, which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract. 
     TECHNICAL FIELD 
     Disclosed herein is a vehicle underfloor structure in which a battery and a suspension member are disposed under a floor of a vehicle. 
     BACKGROUND 
     A vehicle having a battery disposed under a floor of the vehicle has been widely known hitherto. For example, WO 2014/045754 A discloses a technique for disposing a battery under a floor of a vehicle. According to WO 2014/045754 A, a plurality of connectors project from a front end of the battery. 
     However, according to WO 2014/045754 A, nothing is provided directly under the plurality of connectors, and accordingly terminals of the connectors are exposed to the road surface. Therefore, while the vehicle is traveling, an object dropped on the road surface (hereinafter, referred to as an “on-road dropped object”) or a flipped stone may come into contact with the connectors to cause deterioration or damage of the connectors. 
     Here, with a cross member extending in the vehicle width direction provided in front of the battery and below the connectors, the on-road dropped object collides with the cross member before colliding with the connectors as the vehicle advances. Therefore, with provision of such a cross member, the contact between the connectors and the on-road dropped object can be prevented to some extent. However, the cross member located in front of the battery is often located above the lower ends of the connectors. Therefore, in the conventional vehicle, the connectors projecting from the front end of the battery cannot be properly protected. 
     Therefore, disclosed herein is a vehicle underfloor structure that can properly protect the connectors projecting from the front end of the battery. 
     SUMMARY 
     A vehicle underfloor structure disclosed herein includes a battery disposed under a floor of a vehicle and having at least one connector projecting from a front end of the battery, a suspension member provided adjacent to a vehicle front side of the battery, a lower end of the suspension member being located higher than a lower end of the battery, and a protector covering and protecting the at least one connector from below, the protector being laid between the battery and the suspension member. 
     This configuration causes the on-road dropped object to collide with the protector before colliding with the connector as the vehicle advances. As a result, the connector can be effectively prevented from colliding with the on-road dropped object, which in turn makes it possible to properly protect the connector. 
     Further provided is an attachment bar attached to a lower portion of the suspension member and extending in a vehicle width direction, and a front portion of the protector may be attached to the attachment bar. 
     This configuration causes many of the on-road dropped objects to collide with the attachment bar before colliding with the protector. In other words, the likelihood of collision between the protector and the on-road dropped object can be reduced, and the deformation and deterioration of the protector can be suppressed. Further, the attachment bar thus provided allows the front end of the protector to be made low in height. As a result, the inclination angle of the protector can be made almost level. Even when the protector collides with the on-road dropped object, the collision angle can be small, so that deformation or damage of the protector can be more effectively prevented. 
     In this configuration, the lower end of the attachment bar may be located lower than the lower end of the at least one connector and higher than the lower end of the battery. 
     Making the lower end of the attachment bar lower than the lower end of the connector makes it possible to effectively prevent the on-road dropped object from colliding with the protector or the connector. Further, making the lower end of the attachment bar higher than the lower end of the battery makes it possible to prevent excessive lowering of the attachment bar and accordingly reduce the contact of the attachment bar with the road surface. 
     Further, at a rear portion of the suspension member, a rear cross part is provided, the rear cross part having an arch shape, extending in the vehicle width direction, and having a center in the vehicle width direction convex, and the attachment bar is attached to the rear cross part to extend across the arch. 
     This configuration allows the rear cross part of the suspension member having high rigidity to receive the force applied to the attachment bar from the on-road dropped object. 
     The vehicle underfloor structure disclosed herein can properly protect the connector projecting from the front end of the battery. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiment(s) of the present disclosure will be described by reference to the following figures, wherein: 
         FIG. 1  is a plan view of a section around a battery; 
         FIG. 2  is a view seen from A of  FIG. 1 ; 
         FIG. 3  is a perspective view of a protector; 
         FIG. 4  is an enlarged view of a D section of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view taken along B-B of  FIG. 1 ; 
         FIG. 6  is a cross-sectional view taken along C-C of  FIG. 1 ; 
         FIG. 7  is a partial perspective view of an attachment bar as seen from below; 
         FIG. 8  is a schematic side view of a section around the battery and a rear cross part without the protector or the attachment bar, 
         FIG. 9  is a schematic side view of the section around the battery and the rear cross part with the protector but without the attachment bar; 
         FIG. 10  is a schematic side view of the section around the battery and the rear cross part with the protector and the attachment bar; 
         FIG. 11  is a schematic cross-sectional view of a section around a fastening hole in a normal state; and 
         FIG. 12  is a schematic cross-sectional view of the section around the fastening hole in a front collision. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the vehicle underfloor structure will be described with reference to the drawings.  FIG. 1  is a plan view of a section around a battery  10 . Further,  FIG. 2  is a view seen from A of  FIG. 1 . Note that, in each of the drawings, “Fr,” “Up,” and “W” denote a vehicle front direction, a vehicle upper direction, and a vehicle width direction, respectively. 
     The vehicle V is an electric vehicle equipped with at least a motor as a power source, and is, for example, an electric vehicle that travels only by power from the motor, or a hybrid vehicle that travels by power from both the motor and an engine. Under a floor F of the vehicle V, the battery  10  that transfers electric power to and from a traveling motor is disposed. The battery  10  is a chargeable and dischargeable secondary battery such as a lithium ion battery. The battery  10  has a battery case  17  made of metal. Inside the battery case  17 , a battery module constituted by a plurality of battery elements (cells) connected in series or in parallel is housed. In this example, the battery case  17  has a substantially rectangular parallelepiped shape that is flat, and elongated in a vehicle longitudinal direction. 
     A connector  18  that connects the battery module and an external device is attached to a front surface of the battery case  17 . For example, a signal line, a power line, and a refrigerant pipe are connected to the connector  18 . The number of connectors  18  may be appropriately changed as needed, and may be one, or two or more. In the drawings, an example in which three connectors  18  are provided on the front surface of one battery case  17  is illustrated. 
     A suspension member  12  is provided adjacent to a vehicle front side of the battery  10 . The suspension member  12  is a frame member that supports a suspension. The suspension member  12  of this example includes a front cross part  20  and a rear cross part  22  that extend in the vehicle width direction, and a pair of side parts  24  that each connect an end of the front cross part  20  and an end of the rear cross part  22 , and has a substantially square shape. 
     As is apparent from  FIG. 2 , the front cross part  20  has an inverted arch shape whose center in the vehicle width direction is concave. Further, the rear cross part  22  has an arch shape whose center in the vehicle width direction is convex. A lower end of the suspension member  12  is located higher than a lower end of the battery  10 . Further, lower ends of some of the connectors  18  are located lower than the lower end of the rear cross part  22  at positions identical to each other in the vehicle width direction. 
     A protector  14  is laid between the suspension member  12  and the battery  10 .  FIG. 3  is a perspective view of the protector  14 , and  FIG. 4  is an enlarged view of a D section of  FIG. 3 . Note that, in  FIG. 4 , in order to make a through-hole identifiable, sandy hatching is applied to the protector  14 . 
     The protector  14  covers the connectors  18  from below to protect the connectors  18  from contact with a road surface or a flipped stone. The protector  14  is a plate member long in the vehicle longitudinal direction and is, for example, a press-molded member. The protector  14  has a plurality of raised parts  28  that are raised in a thickness direction and a plurality of recessed parts  26  that are recessed in the thickness direction. The raised parts  28  and the recessed parts  26  each extend in the vehicle longitudinal direction. Further, the raised parts  28  and the recessed parts  26  are alternately arranged. As is apparent from  FIG. 3 , neither a width of each of the raised parts  28  nor a width of each of the recessed parts  26  is constant, and the width of the raised part  28  is slightly decreased toward a vehicle rear side. Further, the width of the recessed part  26  is significantly increased toward the vehicle rear side. 
     A front portion of the protector  14  is fastened to the rear cross part  22  of the suspension member  12  using an attachment bar  16  (to be described later). For this fastening, at around a front end of the protector  14 , a fastening hole  30  is formed through which a fastening bolt  42  that is a fastening member is inserted. A diameter of the fastening hole  30  is larger than a major diameter of the fastening bolt  42  and smaller than a diameter of a head of the fastening bolt  42 . The fastening bolt  42  inserted through the fastening hole  30  is screwed into a weld nut  43  fixed to the attachment bar  16  to fasten the protector  14  to the attachment bar  16 .  FIG. 5  is a cross-sectional view taken along B-B of  FIG. 1 , showing how this fastening is performed. 
     The protector  14  further includes a cutout  32  that is located adjacent to a rear side of the fastening hole  30  and partially connected to the fastening hole  30  (see  FIG. 4 ). The cutout  32  is sufficiently wider than the diameter of the head of the fastening bolt  42 . The cutout  32  thus provided allows the protector  14  and the attachment bar  16 ; that is, the protector  14  and the suspension member  12 , to easily disconnect from each other in a front collision. This will be described later. 
     Here, as shown in  FIG. 4 , a portion where the cutout  32  is formed is recessed in a substantially V-shape. That is, the protector  14  includes a recess  34  constituted by a front slope surface  36  inclined to descend rearward and a rear slope surface  38  inclined to ascend rearward that are connected to each other in the vehicle longitudinal direction. A portion of the cutout  32  extends across the front slope surface  36 . The rear slope surface  38  is a flat surface having neither a cutout nor a hole. It can be said that a rear end (i.e., an upper end) of the rear slope surface  38  is located higher than a lower end of the fastening bolt  42  as described in detail later, and the rear slope surface  38  faces the head of the fastening bolt  42  in the vehicle longitudinal direction. 
     Further, as is apparent from  FIGS. 3 and 5 , the fastening hole  30 , the cutout  32 , and the recess  34  are all formed in each of the raised parts  28 . As shown in  FIG. 5 , a projection amount of the raised parts  28  from the recessed parts  26  is greater than a thickness of the head of the fastening bolt  42 . In other words, a lower end of each of the recessed parts  26  is located lower than the lower end of the fastening bolt  42  at a position identical to the fastening bolt  42  in the longitudinal direction. Accordingly, both sides in the vehicle width direction of the fastening bolt  42  are always surrounded by upright walls  40  extending from the raised parts  28  to the recessed parts  26 . This makes other members less prone to coming into contact with the fastening bolt  42 , which in turn makes it possible to effectively prevent damage or loosening of the fastening bolt  42 . 
     A rear portion of the protector  14  is attached directly to a bottom surface of the battery  10  or indirectly to the bottom surface of the battery  10  with a battery frame (not shown) or the like interposed therebetween. The protector  14  may be attached to the battery  10  by fastening using a bolt or a rivet, or by welding. In any case, attaching the rear portion of the protector  14  to the bottom surface of the battery  10  allows the protector  14  to cover the connectors  18  projecting from the front surface of the battery  10  from below. This makes it possible to protect the connectors  18  from contact with a road surface or a flipped stone. 
     In the meantime, in this example, such connectors  18  are disposed above the recessed parts  26  of the protector  14 . This will be described with reference to  FIG. 6 .  FIG. 6  is a schematic cross-sectional view taken along a line C-C of  FIG. 1 . As is apparent from  FIG. 6 , the connectors  18  are all located above the recessed parts  26 . This configuration makes it possible to sufficiently secure a distance between each of the connectors  18  and the protector  14  and accordingly prevent the connectors  18  and the protector  14  from coming into contact with each other. Further, such a configuration allows the protector  14  to be disposed higher than a configuration where the connectors  18  are disposed above the raised parts  28 . As a result, the likelihood of contact between the protector  14  and the road surface can also be reduced. 
     As described above, the protector  14  is fastened to the attachment bar  16 . The attachment bar  16  is a member attached to a lower portion of the rear cross part  22 .  FIG. 7  is a partial perspective view of the attachment bar  16  as viewed from below. In this example, the attachment bar  16  is a rectangular tubular member elongated in the vehicle width direction. A through hole  44  used for fastening the attachment bar  16  to the protector  14  is formed through a bottom surface of the attachment bar  16 . Further, onto a back surface side of the through hole  44 , the weld nut  43  (see  FIG. 5 ) into which the fastening bolt  42  is screwed is fixed. 
     A through hole  46  used for fastening the attachment bar  16  to the rear cross part  22  is formed at an end and through an upper surface of the attachment bar  16 . Further, as shown in  FIG. 7 , the bottom surface of the attachment bar  16  that faces the through hole  46  is largely cut out, allowing insertion of the fastening bolt  48  from below. At a portion of the rear cross part  22  corresponding to the through hole  46 , an insertion hole through which the fastening bolt  48  is inserted is formed, and further, on a back surface side of the insertion hole, a weld nut  50  into which the fastening bolt  48  is screwed is fixed. However, the attachment of the attachment bar  16  to the rear cross part  22  described here is an example, and both the attachment bar  16  and the rear cross part  22  may be attached to each other by a different method such as welding. 
     Here, as described above and shown in  FIG. 5 , the rear cross part  22  has an arch shape whose center in the vehicle width direction is convex. The attachment bar  16  is attached to a bottom surface of the rear cross part  22  so as to extend across the arch. This produces a certain gap between the upper surface of the attachment bar  16  and the bottom surface of the rear cross part  22  at the center in the vehicle width direction. 
     As shown in  FIG. 2 , the attachment bar  16  may have a position and size such that a lower end of the attachment bar  16  is located lower than the lower ends of the connectors  18  and higher than the lower end of the battery  10 . This configuration makes it possible to effectively prevent the protector  14  from coming into contact with an object dropped on a road (hereinafter referred to as an “on-road dropped object”). This will be described later. 
     Next, the reason why the protector  14  and the attachment bar  16  as described above are provided will be described.  FIGS. 8 to 10  are schematic side views of a section around the battery  10  and the rear cross part  22 .  FIG. 8  shows a configuration where neither the protector  14  nor the attachment bar  16  is provided,  FIG. 9  shows a configuration where only the protector  14  is provided but the attachment bar  16  is not provided, and  FIG. 10  shows a configuration where both the protector  14  and the attachment bar  16  are provided. 
     Various objects (on-road dropped objects  100 ) are dropped on a road, and some of the on-road dropped objects  100  are relatively large. When the lower end of the rear cross part  22  is located higher than the lower ends of the connectors  18 , some of such on-road dropped objects  100  may collide with the connectors  18 . For example, as shown in  FIG. 8 , it is assumed that an on-road dropped object  100  lower than the lower end of the rear cross part  22  but higher than the lower ends of the connectors  18  is dropped on a road. In this case, the on-road dropped object  100  passes under the rear cross part  22  and collides with the connectors  18  as the vehicle travels, which may damage or deteriorate the connectors  18 . 
     On the other hand, as shown in  FIG. 9 , it is assumed that the protector  14  that covers and protects the connectors  18  from below is laid between the rear cross part  22  and the battery  10 . In this case, as in  FIG. 8 , even when the on-road dropped object  100  is present, the on-road dropped object  100  collides with the protector  14  before colliding with the connectors  18 . Then, the collision of the on-road dropped object  100  with the protector  14  causes the vehicle to move upward to run over the on-road dropped object  100 , thereby preventing the connectors  18  from colliding with the on-road dropped object  100 . 
     However, since the protector  14  is a thin plate, the protector  14  may be deformed or damaged when colliding with the on-road dropped object  100  with a strong force. In this example, as described above and shown in  FIG. 10 , the attachment bar  16  is interposed between the protector  14  and the rear cross part  22 . The attachment bar  16  extends across the arch formed by the rear cross part  22 . In other words, the attachment bar  16  is attached to a position sufficiently lower than the center in the vehicle width direction of the rear cross part  22 . Accordingly, many of the on-road dropped objects  100  collide with the attachment bar  16  before colliding with the protector  14  as the vehicle travels. When the on-road dropped object  100  collides with the attachment bar  16 , the vehicle moves upward to run over the on-road dropped object  100 . As a result, the contact between the on-road dropped object  100  and the protector  14  is suppressed, which in turn effectively prevents deformation or damaged of the protector  14 . 
     In general, the larger an angle between a direction of the force applied to the protector  14  and the surface of the protector  14 , the more the protector  14  is prone to being deformed, and the more the direction of the force becomes parallel to the surface of the protector  14 , the less the protector  14  is prone to being deformed. When the attachment bar  16  is interposed between the protector  14  and the rear cross part  22 , the height of the front end of the protector  14  is lowered, and the inclination of the protector  14  becomes gentle. That is, an attachment posture of the protector  14  becomes almost level. Accordingly, even when the on-road dropped object  100  collides with the protector  14 , the angle between the direction of the force applied at the collision (generally, parallel to the road surface) and the protector  14  is small. As a result, even when the on-road dropped object  100  collides with the protector  14 , the protector  14  is less prone to being deformed. 
     Here, in order for the on-road dropped object  100  to pass under the lower end of the attachment bar  16  to avoid colliding with the protector  14  and the connectors  18 , the lower end of the attachment bar  16  may be lowered to some degree. However, when the lower end of the attachment bar  16  is excessively lowered, contact between the attachment bar  16  and the road surface frequently occurs. Therefore, in this example, the attachment bar  16  has a position and size such that the lower end of the attachment bar  16  is located lower than the lower ends of the connectors  18  and higher than the lower end of the battery  10 . Such a position and size makes it possible to prevent the on-road dropped object  100  from coming into contact with the protector  14  while suppressing contact between the attachment bar  16  and the road surface. 
     In the meantime, in the front collision where an obstacle collides with the front of the vehicle, a large force (collision load) directed rearward of the vehicle is produced in the suspension member  12 . When the battery  10  and the suspension member  12  are connected by the protector  14 , the collision load is transmitted to the front portion of the battery  10 . The rear portion of the battery  10  is rigidly fixed to a body or frame, so when such a collision load is transmitted to the front portion of the battery  10 , a compressive stress in the vehicle longitudinal direction is undesirably produced in the battery  10 . 
     Therefore, in this example, in order for the protector  14  and the suspension member  12  to easily disconnect from each other in the front collision, the cutout  32  is provided adjacent to the rear side of the fastening hole  30  and connected to the fastening hole  30 . Further, in this example, as described above, the rear slope surface  38  inclined to ascend rearward is further provided adjacent to the rear side of the fastening hole  30 . An effect of the cutout  32  and the rear slope surface  38  will be described with reference to  FIGS. 11 and 12 .  FIGS. 11 and 12  are schematic cross-sectional views of a section around the fastening hole  30 ,  FIG. 11  shows a normal state, and  FIG. 12  shows a state in the front collision. 
     Since the cutout  32  is connected to the rear side of the fastening hole  30 , as shown in  FIG. 12 , the fastening bolt  42  can easily move rearward of the vehicle. Accordingly, when the suspension member  12  and the attachment bar  16  fixed to the suspension member  12  move rearward at the front collision, the fastening bolt  42  also moves rearward of the vehicle and passes through the cutout  32 . This causes the protector  14  and the attachment bar  16 ; that is, the protector  14  and the suspension member  12 , to disconnect from each other to prevent transmission of the load to the front portion of the battery  10 . 
     Here, in this example, the rear slope surface  38  inclined to ascend rearward is provided adjacent to a rear side of the cutout  32 . When the fastening bolt  42  passes through the cutout  32  and moves rearward, the head of the fastening bolt  42  collides with the rear slope surface  38 . A force produced by this collision is converted to a forward and downward force by the rear slope surface  38  inclined to ascend rearward to cause the protector  14  to easily move downward. Then, when the protector  14  moves downward, load transmission to the battery  10  through the protector  14  is more reliably prevented. 
     Note that, in order to cause the fastening bolt  42  to collide with the rear slope surface  38 , the upper end of the rear slope surface  38  needs to be located higher than the lower end of the fastening bolt  42 . Generally, the steeper the inclination angle of the protector  14 , the lower the location of the upper end of the rear slope surface  38 . In this example, interposing the attachment bar  16  between the protector  14  and the suspension member  12  makes the protector  14  almost level. Thus, a difference in height between the upper end of the rear slope surface  38  and the fastening hole  30  can be suppressed, and the fastening bolt  42  can be made to collide with the rear slope surface  38  more reliably. 
     Note that the above description is an example, and as long as at least the protector  14  laid between the battery  10  and the suspension member  12  is provided, the remaining configuration may be changed as appropriate. For example, although in this example the cutout  32  and the recess  34  that are connected to the fastening hole  30  are provided in the protector  14 , any of them is not necessarily provided. Further, the protector  14  and the attachment bar  16  may be attached to each other by not only fastening using a bolt, but also other connections such as fastening using a rivet or welding. 
     Further, the position, size, and shape of the attachment bar  16  may be changed as appropriate. Thus, for example, the attachment bar  16  may have a shape other than the rectangular tubular shape. For example, the attachment bar  16  may have a substantially hat shape having a plate elongated in the vehicle width direction and legs having a substantially L-shape that extend upward from both ends of the plate for fastening to the rear cross part  22 . Further, the protector  14  may be directly connected to the suspension member  12  without the attachment bar  16 . Further, the shape of the protector  14  may also be changed as appropriate, and may be, for example, a flat shape without any of the recessed part  26 , the raised part  28 , and the recess  34 , or may be curved as a whole.