Patent Publication Number: US-2012040219-A1

Title: System for fixing a battery pack and associated automated method of assembly/disassembly

Description:
The present invention relates to a system for attaching a battery pack to a bodyshell such as a bodyshell of a motor vehicle, and to automatable methods for mounting/dismounting such a battery pack. 
     In the field of the attachment of power batteries to a vehicle, no system/method is known that allows an automatable mounting/dismounting. 
     The present invention proposes to make the initial placing and the replacement of a power battery automatable, that is to say able to be carried out without manual technical intervention, for example at a service station. 
     The subject of the invention is a system for attaching a battery pack to a bodyshell, said battery pack comprising a housing, the housing and the bodyshell delimiting between them a space capable of receiving batteries, said housing being furnished with a plurality of at least one device for attaching the housing to the bodyshell on an axis, each device comprising:
         a shaft secured to said housing while being free to rotate about the axis relative to said housing, having at one of its ends a centering shape of revolution about the axis capable of interacting with a complementary shape present on the bodyshell, and at its other end a recess capable of receiving a tool for rotation about the axis;   a cam secured to and rotated by the shaft about the axis and having a substantially flat extension in a plane perpendicular to the axis capable, depending on the angle of rotation of said shaft, of being lodged in or dislodged from a casing made in the bodyshell which casing being substantially flat and perpendicular to the axis,
 
the bodyshell being furnished with one and the same plurality of complementary shape and of casing facing each attachment device.
       

     According to another advantageous feature, each attachment device also comprises an elastic means placed so as to be compressed, on the axis, between the housing and the bodyshell when the cam is placed in the casing, in order to create, when it is relaxed, a bearing force for forcing the extension of said cam against the wall of said casing. 
     The invention also relates to an automatable method for mounting a battery pack comprising such an attachment system, comprising the following steps:
         placing the housing fitted with batteries on a deck, close to the bodyshell,   moving the deck in order to align each centering shape of the plurality of attachment devices of the housing with a corresponding complementary shape of the bodyshell,   moving the deck along the axis in order to insert each centering shape of the plurality of attachment devices of the housing into the corresponding complementary shape of the bodyshell,   rotating each shaft by means of a tool engaged in each recess so as to place each cam of the plurality in each corresponding casing,   removing the deck.       

     The invention also relates to an automatable method for dismounting a battery pack comprising such an attachment system, comprising the following steps:
         placing a deck in contact with the housing,   rotating each shaft by means of a tool engaged in each recess so as to dislodge each cam of the plurality from each corresponding casing,   moving the deck along the axis in order to extract each centering shape of the plurality of attachment devices of the housing from the corresponding complementary shape of the bodyshell,   removing the deck taking away the battery pack.       

     According to another feature of the invention, the mounting and dismounting methods also comprise a movement of the deck along the axis, compressing, if necessary, each elastic means, and the removal of the deck is carried out by relaxing, if necessary, each elastic means. 
     One advantage of the device according to the invention is that it allows automation of the placement and replacement of a power battery pack. 
     Another advantage of the system is that it is based on simple mechanical elements providing good robustness and an ease of industrial application. 
    
    
     
       Other features, details and advantages of the invention will emerge more clearly from the detailed description given below as an indication with respect to the drawings in which: 
         FIG. 1  shows an example of a battery pack in a view from above, 
         FIG. 2  shows this same battery pack in a view from the side, and its placement on the vehicle, 
         FIG. 3  shows an attachment device according to the invention in a perspective view, 
         FIG. 4  shows the same device in an exploded view, 
         FIG. 5  illustrates, on a device seen from above, two planes of section  1  and  2 , 
         FIG. 6 , respectively  7 , shows the attachment device according to the invention in a sectional view along the sectional plane  1 , respectively along the sectional plane  2 , 
         FIGS. 8 and 9  illustrate two steps in the placement of the attachment device on the bodyshell. 
     
    
    
     According to  FIG. 1 , a battery pack  20  has a shape that can be complex. According to the invention it is fitted with a plurality of at least one attachment device  18 , in this instance eight in number and distributed on its periphery, in order to allow the battery pack  20  to be attached to the bodyshell  11 . 
       FIG. 2  illustrates an example of placement of said battery pack  20 , in an illustrative manner, beneath the vehicle  19 . Such a placement is advantageously carried out by means of a movable deck  10 . 
     With reference to  FIGS. 3 and 4  showing a preferred embodiment of an attachment device  18 , respectively shown in a perspective view ( FIG. 3 ) and in an exploded view ( FIG. 4 ), and to  FIGS. 6 and 7  showing two perpendicular sections of the same embodiment, a housing  3  secured to the battery pack  20  is partially illustrated. Said housing  3  is pierced with a circular hole  9 . Into this hole  9  is placed, if necessary, by means of a centering ring  2 , a circular shaft  1  with an axis of revolution Z. Thus said shaft  1  is free to rotate about the axis Z. Said shaft  1  can have a shoulder, as illustrated, in order to butt against the housing  3 . The shaft  1  has at one of its ends a centering shape  13  of revolution about the axis Z. This centering shape  13  is capable of interacting with a complementary shape  14  made on the bodyshell  11 . 
     In the example illustrated, the centering shape  13  is a cylindrical protrusion, while the complementary shape  14  is a cylindrical recess, of slightly greater diameter, in order to be able to receive the centering shape  13  moving in translation along the axis Z. It appears that the shape  13 , respectively  14 , could be any other shape of revolution (for example a cone), the centering shape  13  being able to be a recess or the complementary shape being able to be protrusion, as long as the two shapes  13 ,  14  remain complementary with one another. At its other end, the shaft  1  comprises a recess  15  capable of receiving a tool  12  for rotating about the axis Z. This recess is more evident in  FIGS. 6-9 . 
     Also placed on the shaft  1 , on the side opposite to the shoulder relative to the housing  3 , is a cam  4 . This cam  4  is secured in rotation to the shaft  1 . This securing can be obtained by means of a complementary prismatic profile of the shaft  1  and of the cam  4  at their interface (solution not shown). This securing can also be obtained by means of an attachment of the cam  4  to the shaft  1  achieved, as in the example illustrated, by two screws  7 . Said attachment, in that it traps the housing  3  between the cam  4  and the shaft  1 , secures the attachment device  18  to the housing  3 . 
     The cam  4  is substantially flat on a plane perpendicular to the axis Z and substantially circular in this same plane, except for an extension  17  extending mainly in a radial direction. 
     With reference now to  FIGS. 8 and 9 , the operating method of said attachment device  18  will now be described in detail. The extension  17  is such that it is capable, depending on the angle of rotation of the cam  4  and of said shaft  1 , of being lodged in or dislodged from a casing  16  made in the bodyshell  11 , which casing being substantially flat, perpendicular to the axis Z and placed facing the cam  4 , when the centering shape  13  of the shaft  1  of the attachment device  18  is engaged in the complementary shape  14 . 
       FIGS. 8 and 9  show an attachment device  18  seen from the side and in sectional view, with respect to a detail of the bodyshell  11  comprising a complementary shape  14  capable of receiving the centering shape  13  of the shaft  1  and a casing  16 . In  FIG. 8 , the cam  5  is oriented such that the extension  17  is dislodged from the casing  16 : the attachment device is then unlocked. On the other hand, in  FIG. 9 , the cam  5  is oriented such that the extension  17  is lodged in the casing  16 : the attachment device is then locked. 
     According to a preferred embodiment, the attachment device  18  also comprises an elastic means  5 , in this instance an elastomer part. This means  5  is placed so as to be compressed, on the axis Z, between the housing  3  and the bodyshell  11  when the cam  4  is placed in the casing  16 , in order to create, when the elastic means  5  is relaxed, a bearing force for forcing the extension  17  of said cam  4  against the wall of said casing  16 . Therefore, as illustrated in  FIG. 8 , the device  18  is moved, by a pressure along the axis Z, upward in the plane of the figure, so as, on the one hand, to compress the elastic means  5  and, on the other hand, to allow the cam  4  to be placed facing the casing  16  in order to allow a rotation that will allow it to be put in place. When this rotation has been carried out, as illustrated in  FIG. 9 , said pressure can be relaxed, causing a partial relaxation of the elastic means  5 . The extension  17  of the cam  4  comes into contact along the axis Z with one face of the casing  16 . The residual compression of the elastic means  5  then produces a pressure of the extension  17  of said cam  4  against the wall of said casing  16 . The attachment device  18  is held in position, relative to the bodyshell  11 , under the combined action of the centering of the centering shape  13  with respect to the complementary shape  14 , and of the contact of the cam  4  in the casing  16 . The additional pressure due to the elastic means  5  reinforces this positional hold and makes the attachment better able to withstand the impacts and vibrations that can occur on a vehicle  19 . 
     The elastomer part  5  is assembled with the shaft  1  by means of screws  7 . The two inserted spacers  6  have a height substantially equal to the thickness of the part at the same level as the attachment, so that tightening the screws  7  does not deform said part  5 . 
     A plate  8  is advantageously placed on top of the elastomer part  5  in order to protect it and to spread the compression. It is assembled on the part  5  by any known means, for example by bonding or vulcanization. 
     According to an advantageous arrangement, the battery pack  20  and the housing  3  are placed underneath the bodyshell  11 . Thus the battery pack  20  is protected and mounting/dismounting from beneath the vehicle is possible, for example by means of a hoist or from a pit. 
     In order to be able to place the centering of the centering shapes  13  relative to the complementary shapes  11 , the axes Z of the attachment devices  18  of the plurality are advantageously parallel. 
     In order to combine the advantages of access from beneath and moreover a use of gravity for the placing/replacing of a battery pack  20 , the battery pack  20  then being simply placed on the housing  3 , the axis Z of the attachment devices  18  is advantageously vertical. 
     The attachment system  18  as described above advantageously makes it possible to develop an automatic mounting and/or dismounting method with no manual intervention. 
     Mounting comprises the following steps in succession. The battery pack  20  consisting of the housing  3  furnished with batteries is placed on a deck  10  close to the bodyshell  11 , preferably close to the zone for placement on the vehicle  19 . The deck  10  can be moved and is moved in order to align the axis of each centering shape  13  of an attachment device  18  with the axis of the corresponding complementary shape  14  made in the bodyshell  11 . The deck  10  is then moved parallel to itself, in order to move closer to the bodyshell  11 , by a translational movement along the axis Z. This inserts said centering shapes  13  into said complementary shapes  14  of the bodyshell  11 . In the event of an embodiment with an elastic means  5 , the latter is compressed during this movement. While thus holding the battery pack  20 , the shaft  1  of each attachment device  18  is turned, for example by means of a tool  12  engaged in the recess  15 , in order to engage the extension  17  of the cam  4  in the corresponding casing  16  of the bodyshell  11 . Only one tool  12  can sequentially rotate all of the cams  4 . Alternatively, up to one tool  12  per device  18  can be used. The battery pack  20  is at this stage attached to the bodyshell  11 , and the deck  10  can be removed. If an elastic means  5  is used, the removal of the deck causes a partial relaxation of said elastic means  5  which allows a partial compression of the elastic means  5  to remain, which causes pressure from the cam  4  in the casing  16  and therefore reinforces the attachment. 
     Dismounting comprises steps that are substantially the reverse of the mounting. It comprises the following steps in succession. The deck  10  is placed in contact with the housing  3  of the battery pack  20 . If an elastic means  5  is used, an additional step moves the deck  10 , along the axis Z, closer to the bodyshell  11  in order to compress the elastic means  5  and to align the cams  4  with the casings  16 , in order to remove the pressure previously described so as to make disengagement of the cams  4  easier. The shafts  1  of the attachment devices  18  are then turned, for example by means of one or more tools  12  each engaged in a recess  15 , in order to turn the cams  4  so as to dislodge the extension  17  from the corresponding casing  16 . The deck is then moved along the axis Z, away from the bodyshell  11 , in order to extract the centering shapes  13  from the corresponding complementary shapes  14  of the bodyshell  11 . The battery pack  20  is then detached from the bodyshell and removing the deck  10  allows it to be set down. 
     It is apparent to those skilled in the art that the mounting/dismounting steps can be carried out manually but also advantageously in a totally automated manner.