Abstract:
A rechargeable battery ( 1 ) for hand-guided electromechanical tools, having a plurality of rechargeable battery cells ( 10 ) which are electrically connected to one another by means of electrical cell connectors ( 110 ), wherein the electrical cell connectors ( 110 ) are fixed to a cell connection frame ( 120 ), which is provided on one pole side ( 19 ) of the rechargeable battery cells ( 10 ), for the purpose of simplified mounting of the electrical cell connectors ( 110 ) on the rechargeable battery cells ( 10 ). Furthermore, an electromechanical tool, in particular a cordless screwdriver, a drill, a circular saw, a jigsaw, a sander, a garden appliance, having a rechargeable battery ( 1 ) according to the invention.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP2008/056043 filed on May 16, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a rechargeable battery for hand-guided electromechanical tools, in which the rechargeable battery has many rechargeable battery cells electrically connected to one another. The invention also pertains to an electromechanical tool having a rechargeable battery according to the invention. 
     2. Description of the Prior Art 
     All hand-guided, portable, electrically operated hand tools in which a motor is a usually inseparable component of the tool are called electromechanical tools. Examples are power drills, rechargeable battery cells, circular and saber saws, right-angle sanders, and other power sanders, as well as various garden tools, depending on the design, such as electric hedge shears. Rechargeable batteries or nonrechargeable batteries for such tools should have the highest possible capacity, and a sturdy construction that resists even relatively strong impacts, and should be capable of being produced both simply and furthermore economically. 
     Electrical connections of rechargeable battery cells or battery pack cells inside a rechargeable battery are embodied in the prior art by way of separate cell connections. As a result, particularly with rechargeable batteries that have many rechargeable battery cells, the effort of assembly is high and there are problems in positioning the cell connections. If the electric cell connections are not prefixed by means of a separate device frame or held on the rechargeable battery cells by means of clamping or retaining elements before welding to the poles of the rechargeable battery cells is done, then geometric imprecisions can result in positioning the cell connections. This leads to quality problems with the rechargeable batteries, and in later use, the likelihood of failure of the rechargeable battery can be increased. 
     German Patent DE 100 03 740 C1 discloses a battery with a heat dissipator, and a plurality of battery cells are interconnected with one another in the battery. These battery cells are connected in parallel, and each three battery cells are connected electrically by means of a cell connector and form a battery cell packet. The batter cell packets of the battery are electrically connected by means of current bridges and connected in series. The electrical cell connection and current bridges are each provided separately inside the battery. For dissipation of heat generated in the battery, a flat cooling plate is provided on at least one face end of the battery and is at least indirectly in thermal contact with the cell connections and the current bridges. 
     OBJECT AND SUMMARY OF THE INVENTION 
     It is one object of the invention to disclose an improved rechargeable battery. In particular, it is an object of the invention on the one hand to dispense with pre-fixation of the separate electrical cell connections on the rechargeable battery cells, without having to accept sacrifices in quality in the production of the rechargeable battery. It is furthermore an object of the invention to disclose a robust, economical rechargeable battery that furthermore should be capable of being produced quickly. It is moreover an object of the invention to realize an electromechanical tool having a rechargeable battery of the invention. 
     According to the invention, for simplified, faster and more-economical assembly of the rechargeable battery, an electrical cell connector for rechargeable battery cells of the rechargeable battery is affixed to a cell connection frame, which is preferably of plastic and which can be provided on one pole side of the rechargeable battery. The electrical cell connector and the cell connection frame form the cell connection according to the invention by means of which the rechargeable battery cells can be connected electrically. Preferably, the cell connection frame is spray-coated or coated from behind on the cell connection or cell connections. According to the invention, the separate cell connections that are usual in the prior art are preferably connected to one another by a plastic spray-coating in the form of a frame, thus creating an integrated component comprising a plurality of cell connections and the cell connection frame. 
     As a result, the effort and expense in rechargeable battery assembly in particular is reduced, and constant quality of the welded connections of the individual rechargeable battery cells to the electrical cell connectors is guaranteed, since the cell connection frame can be positioned exactly on a cell cluster of the rechargeable battery. Because of the ease of assembly of the cell connection according to the invention, secure electrical cell connectors are obtained with little fluctuation in quality. As a result, the rechargeable battery and the cell connection is inexpensive, economical, and reliable. The cell connection of the invention is well designed with regard to temperature performance and electrical insulation performance. The cell connection is furthermore safe and reliable because of influence on the geometry of its cell connection frame, since this frame can be adapted to requirements inside the rechargeable battery. 
     The cell connection according to the invention preferably has rectangular or circular through recesses, on or in which contact portions of the electrical cell connectors are disposed. These through recesses, in an assembled cell connection, are disposed on or above the poles of the rechargeable battery cells of the rechargeable battery. The applicable contact portion for a welding tool, in particular a welding electrode, is accessible through the respective through recess, and as a result, a pole of a rechargeable battery cell can be welded to the applicable contact portion. 
     In preferred embodiments of the invention, the electrical cell connectors has a curved transitional portion, and the contact portions of the cell connection can be seated resiliently on the poles of the rechargeable battery cell. This simplifies welding of the contact portions to the applicable poles. In the case of flat cell connectors, it is naturally possible for the contact portions also to be embodied as spring contacts. 
     By means of protrusions and/or recesses, for instance, on the side of the cell connection frame that faces toward the poles of the rechargeable battery cells, the cell connection of the invention can be positioned on the rechargeable battery cells. In other words, by means of a fastening portion formed integrally onto or into the cell connection frame, it is possible to position the cell connection frame quickly and simply on the rechargeable battery cells. Next, the contact portions of the electrical cell connectors are welded to the poles of the rechargeable battery cells. In embodiments of the invention, the cell connection can be locked, clipped or glued to one or a plurality of rechargeable battery cells and/or to a housing of the rechargeable battery. 
     In the cell connection of the invention, the cell connections can furthermore be secured or provided intermittently inside the cell connection frame, and/or the cell connections can intermittently be flush with an outside of the cell connection. In the latter embodiment, space is usually saved compared with the first one mentioned. The plain portions of the cell connections can be electrically insulated from a housing of the rechargeable battery or separately. 
     Further preferred embodiments of the invention will become apparent from the other dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in further detail below in terms of exemplary embodiments, in conjunction with the accompanying drawings. In the drawings: 
         FIG. 1  shows a first embodiment of a cell connection according to the invention in a top view; 
         FIG. 2  shows the cell connection of  FIG. 1  in an assembled state on a plurality of rechargeable battery cells, in a partly sectional side view; 
         FIG. 3  shows a second embodiment of the cell connection of the invention in an assembled state on a plurality of rechargeable battery cells, in a partly sectional side view; and 
         FIG. 4  shows a third embodiment of the cell connection of the invention, in a top view. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention is described in further detail below in terms of a rechargeable battery for hand-guided electromechanical tools. However, the invention not meant to be limited to such hand-guided tools but instead pertains to rechargeable batteries in general. For instance, the invention can be employed with rechargeable batteries for motor vehicles that have internal combustion engines or drive systems of electric motor vehicles. It is also possible for instance to use the invention for rechargeable batteries for portable electronic devices, drives, such as drives for constructing models, and in cell phones, cameras, and the like. 
     When the term “cell connector” is used hereinafter, it is meant to include the term cell terminal for one pole of the rechargeable battery; that is, the invention also pertains to that portion of a rechargeable battery at which the cell connection, in the form of a rechargeable battery pole, is visible on an outside of the rechargeable battery. Dashed lines in the drawings also designate edges that cannot be seen. Conversely, dot-dashed lines represent optional or additional embodiments of the invention. 
       FIGS. 1 and 2  show a rechargeable battery  1  which can also be embodied as a rechargeable battery train or rechargeable battery packet or a nonrechargeable battery. A housing of the rechargeable battery  1  is not shown. The rechargeable battery  1  has four rechargeable battery cells  10 , and an electrical connection of two rechargeable battery cells  10  is effected via an electrical cell connector  110 . It is understood to be possible to provide the rechargeable battery  1  with one more or fewer rechargeable battery cells  10 , and to connect them electrically in series or parallel as needed. 
     The electrical cell connectors  110 , preferably embodied in flat and preferably striplike form, are provided on one pole side  19  of the rechargeable battery cells  10  of the rechargeable battery  1 . The electrical cell connectors  110  are disposed in part on and/or inside a cell connection frame  120 . That is, the cell connection frame  120  and the electrical cell connectors  110  are combined into one component. The cell connection frame  120  here comprises an electrical insulating material and is preferably made from a plastic. In particular, the cell connection frame  120  is integrally injected, or spray-coated, or spray-coated from behind, onto the individual electrical cell connectors  110  by means of an injection molding process. 
     The electrical cell connectors  110  and the cell connection frame  120  of the invention together yield the cell connection  100  of the invention, which is seated on the pole side  19  of the rechargeable battery cells  10 . Contact portions  112  of the electrical cell connectors  110  each contact the rechargeable battery cells  10  at a respective electrical pole  12 . Preferably, the contact portions  112  are welded to the respective pole  12 , preferably spot-welded. However, it is also possible to make an electrical contact of a contact portion  112  with the applicable pole  12  in some other way, which can even be done only via spring forces, for instance. Weld spots  113  connecting the contact portions  112  to the, poles  12  can be seen in  FIGS. 1 and 4 . 
     Particularly if the contact portions  112  are to be welded to the poles  12 , the cell connection frame  120  has through recesses  122 , so that a welding tool (welding horn, electrode, sonotrode) can reach the vicinity of a contact portion  112  that is to be welded to the applicable pole  12 . For that purpose, the through recesses  122  are provided on or in a region of the cell connection frame  120  on or in which the contact portions  112  of the electrical cell connectors  110  are provided. The through recesses  122  are circular, elliptical or rectangular, for instance, but arbitrary shapes of the through recesses  122  can of course be used as well. If welding of the contact portions  112  to the poles  12  is dispensed with, then the through recesses  122  can be left out, and the cell connection  100  can form part of the housing of the rechargeable battery  1 . 
     In the exemplary embodiment shown in  FIG. 2 , the electrical cell connectors  110  are secured by one portion inside the cell connection frame  120 . The region of the electrical cell connector  110  located in the vicinity of the through recess  122  is preferably guided in a region of the through recess  122  via a curved transitional portion  111 . In this respect it is preferable for curved transitional portion  111  to guide the contact portion  112  of the electrical cell connector  110  in a region below an underside  129  of the cell connection frame  120 . In other words, the free contact portions  112  of the applicable cell connectors  110  protrude from the underside  129  or outside of the cell connection frame  120 . The contact portions  112  are located parallel to the underside  129  and preferably also parallel to a top side  128  of the cell connection frame  120 . 
     To compensate for a difference in height among the rechargeable battery cells  10 , the various contact portions  112  are disposed in two planes parallel to one another. However, in other embodiments of the invention, it is possible for all the contact portions  112  of the electrical cell connectors  110  to be disposed in one plane, in which case the applicable poles  12  of the rechargeable battery cells  10  are then also disposed in one plane. 
     In  FIG. 1 , it can be seen that the cell connection  100  or the cell connection frame  120  is aligned with both its long sides with the rechargeable battery cells  10 , and as can also be seen in  FIG. 2 , with its two transverse sides it extends beyond the respective lateral rechargeable battery cell  10 . However, it is also possible to select other configurations. For instance, it is possible for the transverse and long sides of the cell connection frame  120  to be aligned with the rechargeable battery cells  10  or protrude into it or beyond it (in top view). It is also possible to dispose the cell connection frame  120  asymmetrically or partly symmetrically with respect to the rechargeable battery cells  10 . This is indicated in part by the embodiments shown in dashed lines in  FIG. 1 .  FIG. 1  also shows a rechargeable battery cell  10  that is enlarged compared with the rechargeable battery cells  10  shown in  FIG. 2 . 
     To simplify “centering” or preassembly of the cell connection  100  on the rechargeable battery cells  10 , the cell connection  100  can have assembly protrusions  124  on its underside  129  facing toward the rechargeable battery cells  10 . These protrusions are shown in dot-dashed lines in  FIG. 2 . A plurality of assembly protrusions  124  (see also  FIG. 4 ) may be provided. It is moreover possible to provide only one assembly protrusion  124 , which in the assembled state extends all the way around or only partway around the rechargeable battery cells  10  of the rechargeable battery  1 . 
     Another possibility of providing the cell connection  100  according to the invention on the rechargeable battery cells  10  is shown in  FIG. 3 . Here the contact portions  112  of the electrical cell connectors  110  protrude into the corresponding through recesses  122  of the cell connection frame  120 . In other words, the electrical cell connectors  110  are disposed entirely inside an outer boundary of the cell connection frame  120 . Correct seating of the cell connection  100  on the rechargeable battery cells  10  is effected by means of recesses  126 , which are provided in the cell connection frame  120 . The recesses  126  trace the applicable portions of the rechargeable battery pack cells  10 , so that protrusions formed by the recesses  126  come to rest in free spaces between two or four rechargeable battery cells  10 . As shown in  FIG. 3 , the cell connection  100  according to the invention may be embodied as overall shorter than the rechargeable battery cells  10  disposed side by side.  FIG. 3  furthermore shows an embodiment of the invention with an assembly protrusion  124  which is provided on one long end of the cell connection frame  120  and which in the assembled state conforms to one or a plurality of rechargeable battery cells  10 . 
       FIG. 3  furthermore shows an embodiment in which a top side  128  (in dot-dashed lines) of the cell connection frame  120  is aligned with at least one electrical cell connector  110  ( FIG. 3 , top center). Naturally, it is also possible for a plurality of electrical cell connectors  110 , or all of them, to be aligned by at least one portion with the top side  128  of the cell connection frame  120  (this is not shown in the drawing). In such embodiments of the invention, it is preferable that the electrical cell connectors  110 , in those portions on which they have material contact with the cell connection frame  120 , have corresponding recesses, preferably through recesses, into which the fluid plastic can flow in the spray-coating process, so as to affix the electrical cell connectors  110  to the cell connection frame  120 . Naturally, it is also possible for this to be done only later upon assembly of the electrical cell connectors  110  on an already-completed cell connection frame  120 . 
       FIG. 4  shows an embodiment of the cell connection  100  according to the invention in which two rows each of four rechargeable battery cells  10  are connected electrically in series to one another. This can be seen from the arrangement of the poles  12  of the rechargeable battery cells  10 . A cell connection  100  according to the invention located opposite that face end then connects the rechargeable battery cells  10  not shown in  FIG. 4  accordingly. That side then also has the poles  12  of the rechargeable battery  1 . In all the embodiments of the invention, it is possible for this side of the rechargeable battery  1  to be electrically interconnected with conventional cell connections. 
       FIG. 4  furthermore shows an alternative preferred electrical contact portion  112  ( FIG. 4 , bottom center), which has two tongues, and each tongue is connected electrically to the pole  12  of the rechargeable battery cell  10  by means of a weld spot  113 ; the two tongues are separated from one another via a gap.  FIG. 4  furthermore shows an alternative rechargeable battery cell  10  in its cross section, which is constructed as approximately square or nearly rectangular. As a result, the space inside the rechargeable battery  1  can be utilized more effectively. 
       FIG. 4  furthermore shows alternative assembly protrusions  124 . On the one hand, one such assembly protrusion  124  is provided in all four corner regions of the cell connection frame  120 . Alternatively or in addition, it is possible to provide the assembly protrusions  124  in a middle region of the cell connection frame  120 . This is shown as an example by means of two peglike assembly protrusions  124 . 
     The invention is of course also usable with only a single electrical cell connector  110  that connects two rechargeable battery cells  10  to one another. In that case, the cell connection frame  120  is preferably embodied as a land between the two contact portions  112  of the electrical cell connector  110 . 
     The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.