Abstract:
The invention relates to an accumulator ( 10 ), particularly a prismatic lead accumulator, comprising a housing and (a) at least one stack ( 29 ) of plates, (b) which has a plurality of spaced-apart pole plates ( 14, 16 ) that are entirely suspended by a fixing element ( 28 ) in at least one circumferential direction (U). According to the invention, the fixing element ( 28 ) is fixedly connected to the housing ( 19 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to an accumulator, in particular a lead-acid accumulator having a housing and at least one plate stack which is arranged in the housing, wherein the plate stack has a multiplicity of pole plates which are separated from one another and are completely surrounded by a fixing element, at least in a circumferential direction. According to a second aspect, the invention relates to a method for production of an accumulator. 
     BACKGROUND 
     An accumulator of this generic type is known, for example, from DE 20 2006 001 509 U1. There, a fixing element in the form of a thermoplastically welded tape is used, in order to hold the pole plates of the plate stack together. One major advantage of this arrangement is that the housing of the accumulator can be designed to have thin walls, since it need no longer exert pressure on the plate stack in order to ensure the accumulator is sufficiently resistant to shaking. In order to withstand, in particular extremely severe shaking loads without damage, the housing must, however, still have considerable strength. This leads to the consumption of a large amount of material for the production of the housing, and to the accumulator being heavy. A further disadvantage is that the plate stacks must be manufactured with high geometric accuracy. This is because, on the one hand, the plate stack must be large enough to make contact with the housing all the time, even in the event of a severe shaking load. On the other hand, the plate stack must be sufficiently small that it is not damaged during insertion into the housing. This stringent accuracy requirement for the plate stack and the housing leads to high manufacturing costs. 
     SUMMARY OF THE DESCRIPTION 
     The invention is based on the object of overcoming the disadvantages of the prior art. 
     The invention solves the problem by an accumulator of this generic type in which the fixing element is firmly connected to the housing. According to a second aspect, the invention solves the problem by means of a method having the following steps: (a) provision of a housing, (b) provision of a plate stack which has a multiplicity of pole plates which are separated from one another, (c) surrounding of the plate stack with a fixing element which is circumferential in a circumferential direction, (d) then, insertion of the plate stack into the housing, and (f) connection of the fixing element to the housing. 
     The invention has the advantage that the shaking resistance of the accumulator is increased, and the geometric requirements for the plate stack can be reduced at the same time. With the geometric requirement for the plate stack remaining unchanged, this advantageously minimizes the risk of damage occurring to the housing or the plate stack when the plate stack is being inserted into the housing. 
     A further advantage is that manufacturing can be carried out easily, which means that existing manufacturing facilities can easily be converted. 
     A further advantage is that the shaking resistance of the accumulator is increased with the wall thickness of the housing remaining unchanged. For a predetermined shaking resistance of the accumulator, the wall thickness of the housing can advantageously be reduced, which leads to less material being consumed and to a lighter-weight accumulator. 
     For the present description, a fixing element means, in particular, any component of the accumulator which exerts a force on the pole plates of the plate stack such that the pole plates cannot be moved away from one another. It is possible, but not necessary, for the fixing element to hold the pole plates together. It is also possible for the pole plates to be held together in some other manner, for example by means of joint connections. Examples of fixing elements are sealing straps, casings, sheaths having recesses, or meshes. By way of example, fixing elements can be connected to the plate stack by adhesive bonding or welding to the plate stack, looping and/or adhesive bonding to the plate stack. 
     The expression that the fixing element is firmly connected to the housing means in particular that the fixing element is attached to the housing such that accelerations and vibrations which typically occur in the case of an accumulator do not, lead to the fixing element becoming detached from the housing. It is possible for the fixing element to be joined directly to the housing, for example by welding, pressing on and/or pressing in. It is particularly advantageous for the fixing element to be adhesively bonded to the housing. 
     In one preferred embodiment, the fixing element is connected to a bottom of the housing. Alternatively or additively, the fixing element is also connected to an inner face of a side wall of the housing. If there are a plurality of side walls of the housing in the vicinity of the fixing element, the fixing element is preferably connected to all, these side walls. This results in particularly good resistance to shaking. 
     The housing preferably has T-shaped ribs which project into an internal area of the housing, and the fixing element is preferably connected to the T-shaped rib or ribs. An accumulator such as this has two advantages. On the one hand, the T-shaped ribs and the connection to the plate stack via the ribs result in particularly good resistance to shaking. On the other hand, the fixing element makes it easier to insert the plate stack in the direction of the ribs. In general, the plate stack is inserted along a longitudinal extent of the ribs. If the plate comes into contact with an edge of the rib during insertion, then it slides away from the edge on the fixing element, avoiding damage to the plate stack. 
     Particularly good resistance to shaking is achieved if the fixing element is also connected to a cover of the housing. 
     One particularly suitable option for connecting the fixing element to the housing is adhesive bonding, with an acid-resistant and/or lye-resistant adhesive joint advantageously being provided. 
     A fiber-reinforced plastic tape, for example composed of polypropylene, polyethylene, polyvinyl chloride or polyethylene terephthalate, has been found to be a suitable fixing element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One exemplary embodiment of the present invention will be explained in more detail in the following text with reference to the attached drawings, in which: 
         FIG. 1  shows a longitudinal section through an accumulator according to the invention, and 
         FIG. 2  shows a second section, at right angles to the section shown in  FIG. 1 , through a second embodiment of an accumulator according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a cross-sectional view of an accumulator  10  which comprises electrochemical cells  12 . 1  to  12 . 6  of which the electrochemical cells  12 . 1 ,  12 . 2  and  12 . 3  are shown in  FIG. 1 . The electrochemical cells  12 . 1 ,  12 . 2 ,  12 . 3  each comprise a multiplicity of pole plates  14 . 1 ,  14 . 2  and  14 . 3 , respectively, which are separated from one another and form a positive plate set, and negative pole plates  16 . 1 ,  16 . 2  and  16 . 3 , respectively, which form a negative plate set. The electrochemical cells  12 . 1  to  12 . 3  are physically separated and electrically isolated from one another by partition walls  18 . 1 ,  18 . 2 , and are arranged in a housing  19 . In the following text, a reference symbol with a numerical suffix “.1”, “.2”, . . . denotes the respective specific object. Reference symbols without a numerical suffix denote the object in general. 
     The positive pole plates and the negative pole plates are each separately mechanically and electrically connected to a connector  20 . 1 ,  20 . 2 ,  20 . 3  and  20 . 4 . Two respective connectors  20 . 1  and  20 . 2  as well as  20 . 3  and  20 . 4  are electrically and mechanically connected to one another through an opening, which is not shown, in the respective partition wall  18 . 1  or  18 . 2 , as a result of which the electrochemical cells  12 . 1  to  12 . 3  are connected in series. Contact is made with the accumulator via a positive pole  24  and a negative pole  26  ( FIG. 2 ). 
     As shown in  FIG. 1 , the pole plates  14 ,  16  are completely surrounded by two fixing elements  28 . 1 ,  282  in a circumferential direction which is indicated by an arrow U and runs at right angles to the longitudinal direction of the accumulator  10 , and these two fixing elements  28 . 1 ,  28 . 2  hold the pole plates  14 ,  16  together, thus forming respective plate stacks  29 . 1 ,  29 . 2 ,  29 . 3 . The fixing elements  28 . 1 ,  28 . 2  have a fixing element width B which, for example, is between 20 mm and 30 mm. It is also possible to enclose the pole plates  14 ,  16  in a circumferential direction which runs parallel to the longitudinal direction of the accumulator  10 . 
     The fixing elements  28 . 1 ,  28 . 2  are firmly connected to a bottom  32  of the housing  19  by means of adhesive points  30 . 1 ,  30 . 2  on the bottom face. The fixing elements  28 . 1 ,  28 . 2  are furthermore connected to a side wall of the housing  19  via lateral adhesive points  34 . 1 ,  34 . 2 . 
       FIG. 2  shows a horizontal cross section through a second embodiment of an accumulator according to the invention. In the embodiment shown in  FIG. 2 , the housing  19  has a multiplicity of T-shaped ribs  36 . 1 ,  36 . 2 , . . . , which project into an internal area  38  of the accumulator. The T-shaped ribs  36 . 1 , . . . have a rib width R, which is smaller by a small amount than the fixing element width B of the fixing elements. 
     In the embodiment shown in  FIG. 2 , the plate stack  29  is surrounded by three fixing elements  28 . 1 ,  28 . 2 ,  28 . 3 . Each of the three fixing elements  28 . 1  to  28 . 3  is connected, analogously to the situation shown in  FIG. 1 , to the bottom of the housing  19  by means of three adhesive points, which are not shown that are at the bottom face. The fixing elements  28 . 1  to  28 . 3  are arranged on the plate stack such that they are directly opposite the T-shaped ribs  36 . 1  to  36 . 3  and are connected to them via lateral adhesive points  34 . 1 ,  34 . 2  and  34 . 3 . 
     Furthermore, the housing  19  has a longitudinal partition wall  40  which separates the electrochemical cells  12 . 1  to  12 . 3  from the electrochemical cells  12 . 4  to  12 . 6 . The fixing elements  28 . 1 ,  28 . 2 ,  28 . 3  are additionally fixed to the longitudinal partition wall  40  by means of lateral adhesive points  34 . 4 ,  34 . 5 ,  34 . 6  facing the longitudinal partition wall. Furthermore, adhesive points  42 . 1 ,  42 . 2  are provided on the cover face, in order to permanently connect the fixing elements to a cover, which is not shown. 
     The accumulator  10  is produced by first of all injection-molding the housing  19 . Plate stacks  29  are furthermore formed from the positive and negative pole plates  14 ,  16 , and are surrounded by one, two, three, four or more fixing elements  28 . The fixing elements  28  are then provided with adhesive and are then inserted into the housing  19 , in an insertion direction which is indicated by an arrow E. During the process, the adhesive comes into contact with the housing  19 , and is cured. Battery liquid is then added, the adhesive points  42  on the cover face are applied, and a cover which is not shown is welded in a gas-tight manner to the existing housing, thus completing the production of the accumulator  10 . 
     LIST OF REFERENCE SYMBOLS 
     
         
           10  Accumulator 
           12  Electrochemical cell 
           14  Positive pole plates 
           16  Negative pole plates 
           18  Partition wall 
           19  Housing 
           20  Connector 
           22  Connector 
           24  Positive pole 
           26  Negative pole 
           28  Fixing element 
           29  Plate stack 
           30  Adhesive point on the bottom face 
           32  Bottom 
           34  Lateral adhesive point 
           36  T-shaped rib 
           38  Internal area 
           40  Longitudinal partition wall 
           42  Adhesive point on the cover face 
         U Circumferential direction 
         B Fixing element width 
         R Rib width 
         E Insertion direction