WO2013149668A1

WO2013149668A1 - Battery pack

Info

Publication number: WO2013149668A1
Application number: PCT/EP2012/056284
Authority: WO
Inventors: Joachim Rief
Original assignee: Husqvarna Ab
Priority date: 2012-04-05
Filing date: 2012-04-05
Publication date: 2013-10-10
Also published as: CN104205410A; CN104205410B; DE112012006185T5; DE112012006185B4

Abstract

Battery pack with a battery cell assembly (1) comprising: - at least one first component (4 or 5) being a connector component; - at least one second component (2 or 4), wherein said first connector component (4 or 5) is in electrical contact to said second component (2 or 4); - at least one wall structure (7) which is arranged adjacent to said first connector component (4 or 5) and said second component (2 or 4); - and at least one retaining element (9) which is provided on said first connector component (4 or 5) and/or on said second component (2 or 4) and/or on said wall structure (7), wherein said retaining element (9) fixes said first connector component (4 or 5) and/or said second component (2 or 4) in its position relative to said wall structure (7).

Description

Battery pack

The present invention is related to a battery pack.

Common battery packs comprise a plurality of battery cells which are arranged in a housing and interconnected with each other electrically . The document US 5,096,788 A discloses a battery pack comprising a housing and a plurality of cells within the housing, each cell having a positive and negative terminal. A flex circuit is pro^¬ vided for interconnecting the plurality of cells. The battery pack additionally comprises biasing means for providing suffi- cient contact pressure between the flex circuit and the cell terminals. Shock pads are used to dampen the movement of the cells when the battery pack is dropped or receives a sudden im^¬ pact. The cells have their respective adjacent positive and neg^¬ ative terminals connected together via steel tabs. The steel tabs are typically spot welded to the terminals and then welded or soldered to the contacts of the flex circuit. Since the steel tabs are welded to the flex circuit, there is little concern whether enough force exists between cell terminals and the con^¬ tacts .

The further document US 2010/0310922 Al discloses a lithium ion battery including a housing and a top attached to an open end of the housing. The battery pack includes a plurality of battery cells, arranged in parallel and contained in the housing. The battery pack further includes cathode and anode current collec^¬ tors. Each of the current collectors includes a collector plate welded to a collector plate tab. The collector plate tabs are welded to the respective cathode and anode covers of the battery cells . Known battery packs have the disadvantage, that in the case of a drop or another impact, forces affect the welding connections of the battery pack and these welding connections can be damaged or broken. In those cases, the electric connection established by the welding connection would not work.

Therefore it is an object of the invention to provide an im^¬ proved battery pack, wherein fixing connections, such as welding connections, are more robust or protected against mechanical collapse or malfunction.

It is a further object of the invention to provide a recharge^¬ able battery for garden tools which is robust and reliable under rough conditions and which resists sudden impacts.

This object is obtained by claims 1, 21 and 22. Advantageous em^¬ bodiments result from dependent claims.

According to claim 1 a battery pack with a battery cell assembly comprises at least one first component being a connector compo^¬ nent, at least one second component, wherein said first connec^¬ tor component is in electrical contact to said second component, at least one wall structure which is arranged adjacent to said first connector component and said second component, and at least one retaining element which is provided on said first con^¬ nector component and/or on said second component and/or on said wall structure, wherein said retaining element fixes said first connector component and/or said second component in its position relative to said wall structure.

A sudden impact, e.g. from a drop of the battery pack, may re^¬ sult in a displacement of the first component and in a mechani^¬ cal impact or displacement of the first component and/or second component which influences the electrical connection between both. Having a retaining element as described above, the first component and/or second component are additionally secured in their relative positions. A movement of the first connector com- ponent and/or the second component is at least impeded, but still possible.

According to a further embodiment of the invention said first connector component is fixedly attached to said second compo^¬ nent .

Thus, the electrical connection between the components is se^¬ cured also under rough conditions. By means of the retaining el- ements, the fixed connection is at least partially protected from forces resulting from impacts.

According to a further embodiment of the invention said first connector component is a connector bridge and said second compo- nent is a battery cell.

A retaining element is particularly useful, when a connector bridge is used to interconnect two or more battery cells. The connections between the connector bridge and the battery cells are protected from being damaged or displaced in the case of a drop or a sudden impact, when a retaining element is provided that impedes a movement of the connector bridge in the position where it is connected to the battery cell. In an alternative embodiment of the invention said first connec^¬ tor component is a connector element and said second component is a connector bridge.

Retaining elements are also useful, when a connector element in- terconnects a connector bridge, e.g. to a circuit board. For ex^¬ ample, when the connector element is bent into its final posi^¬ tion, resilient spring-back forces in the connector element might cause a stress or tension, e.g. on a welded connection be^¬ tween connector element and connector bridge. By means of the retaining elements the connector bridge can be protected from being drawn out of its position and stresses on the connection between connector element and connector bridge can be reduced. According to a further embodiment of the invention said wall structure is arranged substantially perpendicular to a planar extension of said first connector component.

When the retaining element can interact with a wall structure that is perpendicular to the first connector component, the re^¬ taining function can be optimized. According to a further embodiment of the invention said first component has at least one fixing section and said first compo^¬ nent is connected to said second component via at least one fix^¬ ing connection. In such a way, a defined section is provided on the first compo^¬ nent, which is formed and/or dimensioned in order to establish a stable fixing connection to the second component. Thus, a robust electrical connection is formed between both components. According to a further advantageous embodiment of the invention said wall structure is formed substantially U-shaped, and said fixing section is formed correspondingly to the shape of said wall structure and is at least partially surrounded by said wall structure .

Thus, the fixing section of the first component fits in between the wall structure, wherein a displacement of the fixing section relative to the wall structure is avoided or at least impeded. A configuration with a wall structure that is formed correspond- ingly to the fixing section, is advantageous for an easy arrangement of the retaining element.

According to a further advantageous embodiment of the invention said fixing section is a welding section and said first compo- nent is connected to said second component via at least one welding connection. A welding connection connects the first and second component in a very stable way. The electric contact between the components is established reliably. Further, stresses resulting from me^¬ chanical impacts on the battery cell assembly and on the welding connection can be supported or absorbed at least partially.

According to a further embodiment of the invention said first connector component has at least one, preferably two, retaining elements, preferably formed integrally to said first connector component, in particular two retaining elements arranged on op^¬ posing sides of said fixing section of said first connector component, wherein each of said two retaining elements abuts on a different wall of said wall structure. The retaining element can be arranged on the wall structure ad^¬ jacent to the fixing section. Thus, the fixing section can be held or clamped with sufficient forces and in a very quick mounting process. Further, the position of the first connector component can be fixed prior to the fixation process, e.g. weld- ing process.

In a further advantageous embodiment of the invention said at least one, preferably two, retaining elements abut inclined on said wall structure or said at least one, preferably two, re- taining elements are arranged angularly relative to said wall structure .

The retaining elements are slightly inclined or angled in a di^¬ rection that a linear movement as well as a rotational movement of the first connector component is at least partially impeded along the wall structure.

In a further advantageous embodiment of the invention at least one connector element is fixed, preferably welded, to said con- nector bridge, wherein said connector element provides a first force loaded on said connector bridge, said first force drawing said connector bridge out of its intended position, wherein said at least one retaining element clamps in a force closure provid^¬ ing a second force in an opposing direction to said first force provided by said connector element. Thus, the drag force affecting the connector bridge resulting from a spring-back resilience of the connector element can be biased or at least partially reduced. The tendency of the con^¬ nector bridge to be drawn out of position is at least partially compensated .

In a further advantageous embodiment of the invention a resil^¬ ient force affects said connector element loading a stress on said fixing connection, wherein said at least one retaining element clamps in a force closure to said wall structure and pro- vides a force affecting in an opposing direction to said stress on said fixing connection.

In such a configuration, the fixing connection is at least partially relieved from the stress that affects thereto. In the case of a drop of the battery pack, the stress would result in a worse damage of the connection. By means of the retaining ele^¬ ment the stress in the connection can be reduced which reduces the risk of damage of the connection in the case of a drop. In a further advantageous embodiment of the invention said fix^¬ ing section is a welding section, which comprises at least one first welding section and at least one second welding section, wherein said first welding section is separated from said second welding section by a recess and wherein at least one retaining element is arranged on each of said first and second welding section .

With such a recess a displacement of the fixing sections or forces on the fixing sections can be compensated. In cooperation with said retaining elements such recesses can provide addi^¬ tional resilience to the clamping connection. Further, the insertion of the first connector component into its intended posi- tion can be relieved, while the extraction or removing of the first connector component is impeded.

In a further advantageous embodiment of the invention said con- nector bridge has a H-shaped form or a T-shaped form or an L- shaped form or an I-shaped form, wherein said at least one, preferably two, retaining element is arranged on at least one end section of a leg of said H-shaped form or at least one end section of a cross bar of said T-shaped form or at least one end section of a leg of said L-shaped form or at least one end sec^¬ tion of said I-shaped form, in particular wherein at least one, preferably two, retaining element is arranged on each end sec^¬ tion of each leg of said H-shaped form or on each end section of the crossbar of said T-shaped form or on each end section of each leg of said L-shaped form or on each end section of said I- shaped form.

Providing the retaining elements on the legs of the specifically shaped connector bridges allows to secure the connector bridge in an advantageous way in that positions where the welding con^¬ nections are provided.

In a further advantageous embodiment of the invention said first component comprises at least one pair of retaining elements which forms a pair of barbed hooks providing resistance against movement of said first component.

A particular advantageous configuration is achieved, when two retaining elements work as barbed hooks. Then, clamping connec- tion on the wall structure is very effective.

In a further advantageous embodiment of the invention said con^¬ nector bridge comprises at least one first retaining element and said wall structure comprises at least one second retaining ele- ment, wherein said first retaining element and said second re^¬ taining element are arranged on opposing sides of said connector bridge . In such a configuration the connector bridge can be installed in between the wall structure e.g. by a rotational movement. Once installed, the retaining elements impede the displacement of the connector bridge due to forces applied in an impact or from a connector element as described above.

In a further advantageous embodiment of the invention said first retaining element is arranged inclined relative to said wall structure and said second retaining element is arranged substan^¬ tially perpendicular to said wall structure.

Thus, the effect of the first retaining element which can clamp on the wall structure is intensified. The second retaining ele- ment can additionally act as a holder for the second component.

In a further advantageous embodiment of the invention said wall structure comprises two retaining elements on opposing sides of said first component, wherein said first component comprises at least one recess which divides said first component into a first fixing section and a second fixing section in the region of said retaining elements in such a way, that said first fixing section and said second fixing section can snap into the geometry formed by the wall structure and the retaining elements.

A snapping connection allows easy installation of the connector bridge. The snapping connection could be designed releasable or not releasable. Further the connector bridge can be brought re^¬ liably into its proper position.

In a further advantageous embodiment of the invention the wall structure has at least one cutout adjacent to each of said re^¬ taining elements. The cutouts facilitate the mounting of the welding sections un^¬ der the retaining elements in an advantageous way. According to a further advantageous embodiment of the invention at least one battery cell is electrically connected via said first component and/or via said second component to at least one terminal unit of said battery cell assembly.

A terminal unit shall be understood as a means for interconnect^¬ ing and/or controlling the several voltages or currents generated by the several battery cells, in particular as a circuit board comprising further electric connecting means and/or elec- trie control means. In such a manner a very stable electric con^¬ nection between the battery cells of the battery pack and the terminal unit is created, being highly resistant against me^¬ chanical impacts or shocks. Particularly advantageous is to provide a battery pack embodying the inventive features in a rechargeable battery. Rechargeable batteries are often manipulated and the risk of impacts is very high. Therefore rechargeable batteries need to be very robust against drops and impacts, which is achieved in using a battery pack as defined in the claims 1 to 20.

Further advantageous is to provide a handheld garden tool with a rechargeable battery that comprises a battery pack according to one of the claims 1 to 20. In particular in rough working envi- ronment, the rechargeable battery has to be very stable and re^¬ liable .

For further embodiments and configurations, advantages and ad^¬ vantageous effects, reference is made to the description above and further above.

Selected embodiments of the invention will now be described in connection with the annexed figures, in which:

Fig. 1 shows a perspective view of a battery cell assembly in an intermediary assembly step; shows a perspective view of a battery cell assembly af ter the mounting of connector elements 5 onto the connector bridges 4a to 4f; shows a side view of a battery cell assembly; shows a detailed view of a connector element embodying the invention; shows a detailed sectional view of the connector ele^¬ ment according to Fig. 4; shows a side view of a battery cell assembly; shows a detailed view of a connector bridge according to Fig. 6;

Fig. 8 shows a top view of a connector element welded to a connector bridge in an installed position on a cover element ;

Fig. 9 shows a sectional view B-B of the connector bridge as indicated in Fig. 8;

Fig. 10 shows a top view of a connector element welded to a connector bridge in an installed position on a cover element having a different configuration of retaining elements ;

Fig. 11 shows a sectional view C-C of the connector bridge as indicated in Fig. 10;

Fig. 12 shows a sectional view D-D of the connector bridge as indicated in Fig. 10; Fig. 1 shows a perspective view of a battery cell assembly 1 in an intermediary assembly step. The battery cell assembly 1 com^¬ prises a plurality of battery cells 2 formed as cylindrical ele^¬ ments which are combined juxtaposed in a battery. In this spe- cific embodiment the battery cell assembly 1 comprises 20 bat^¬ tery cells 2. The front end and the back end of the cylindrical elements of the battery cells 2 are fixedly attached to a first cover element 3a and a second cover element 3b. Battery cell as^¬ semblies 1 of that kind are e.g. used for rechargeable batteries or accumulators in particular for handheld devices, such as gar^¬ den tools, e.g. hedge trimmers, blowers, chainsaws, brushcut- ters, trimmers or the like.

Each end of each battery cell 2 is electrically connected to a connector bridge 4a, 4b, 4c, 4d, 4e, 4f as shown in Fig. 1. In this embodiment four battery cells 2 are electrically connected to each one of the connector bridges 4a, 4b, 4c, 4d which have an H-shaped form. Two battery cells 2 are electrically connected to each one of the connector bridges 4e, 4f which have an I- shaped form. For example, the I-shaped connector bridges 4e, 4f can each connect two battery cells 2 in series, wherein these pairs of serially connected battery cells 2 can be connected in parallel. Correspondingly, this is possible by means of the H- shaped connector bridges 4a to 4d with a plurality of battery cells 2. Also different shapes for the connector bridges 4a to 4f could be used, depending on the design of the battery cell assembly 1.

On a lateral side of the battery cell assembly 1 a terminal unit, e.g. a circuit board 6 is arranged, whereupon electronic components and electrical connection means can be arranged. A terminal unit shall be understood as a means for interconnecting and/or controlling the several voltages or currents generated by the several battery cells 2. For connecting the battery cells 2 electrically with the circuit board 6 connector elements 5 are provided. Connector bridges 4a to 4f and connector elements 5 are both formed as flat metal sheet elements, e.g. made from nickel plated steel or copper or the like. Along a bending line 13, the connector elements 5 can be brought into a final posi^¬ tion .

In a pre-mounted situation the connector elements 5 are attached to the circuit board 6. After attaching the circuit board 6 to the first and second cover elements 3a, 3b, the connector ele^¬ ments 5 are arranged in a predetermined position relative to the connector bridges 4a to 4f. Fig. 2 shows a perspective view of a battery cell assembly 1 af^¬ ter the mounting of the connector elements 5 onto the connector bridges 4a to 4f. During the mounting process, the connector el^¬ ements 5 are bent along a bending line 13 in a direction towards the connector bridges 4a to 4f. It is possible, that the first end sections of the connector elements 5 are attached to the circuit board 6 by engaging around an edge or rim of the circuit board 6. The opposite end sections of the connector elements 5 are in contact with the connector bridges 4a to 4f. Said contact can be a plane contact or a contact where only one or a few points of the surfaces of each component contact each other. In particular, the connector elements 5 are connected to the cir^¬ cuit board 6 by a soldering process, more precise, the connector elements 5 are soldered into holes on the circuit board 6. The connector elements 5 can be supplied to the assembly line as pre-formed or pre-bent components, then attached to the circuit board 6 and after that bent or brought into a final form for es^¬ tablishing an electric contact between the connector bridges 4a to 4f and the circuit board 6. The figures 1 and 2 show a battery cell assembly 1 which com^¬ prises 20 battery cells 2, whereas the following figures show a battery cell assembly 1 which comprises 10 battery cells 2.

Fig. 3 shows a side view of a battery cell assembly 1. The lay- out of the battery cell assembly 1 may differ from that accord^¬ ing to the above described figures. However, the inventive fea^¬ tures can be explained with reference to an overall view of the figures. The second cover element 3b of the battery cell assem^¬ bly 1 comprises a connector bridge 4 which connects two of the battery cells 2 over the connector element 5 to the circuit board 6. Further connector bridges are arranged on the second cover element 3b which each connects two of the battery cells 2 or a single battery cell 2 via the connector element 5 to the circuit board 6. The connector bridges 4 on the battery cell as^¬ sembly 1 in this figure have T-shaped or L-shaped forms.

Fig. 4 shows a detailed view of a connector element 5 which is in contact with the connector bridge 4. An end section 12 of the connector element 5 has a fixing section which is formed as a first welding section 5a and a second welding section 5b, wherein first and second welding sections 5a, 5b are distanced from each other by a recess 8. In a direction towards a middle sec^¬ tion 11 of the connector element 5 first and second welding sec^¬ tions 5a, 5b conjoin or merge together and form the middle sec^¬ tion 11.

The connector element 5 is fixed to the connector bridge 4 by means of a welding connection. It is also possible, that the fixation is obtained in another useful way, for example by means of a soldering connection or by means of screws which are applied to the fixing section. It is further possible, that the fixing section is pressed to its counterpart by means of a spring. In general, a section shall be understood as a fixing section, where the fixing means engaging.

In an alternative embodiment, the connector element 5 can be held in electrical contact to the connector bridge 4 by means of screws or by means of a spring, pressing the connector element 5 onto the connector bridge 4 or one or both of the components on^¬ to a respective battery cell 2.

On each of the first and second welding sections 5a, 5b two welding spots are arranged, welding first and second welding section 5a, 5b fixedly to the connector bridge 4. It is also possible to provide only one or more than two welding points or welding spots. By means of the recess 8 displacements of first and second welding section 5a, 5b caused by thermal or mechani^¬ cal stress can be compensated. After being bent into its final position, the connector element 5 tends to move back in its previous or pre-bent position. This is caused by the spring-back resilience present in the material of the connector element 5 induced by the bending process. This results in a spring-back force which impacts on the connector element 5 and consequently on the welding connection between first and second welding sections 5a, 5b and connector bridge 4. More precisely, the end section of the connector element 12 tends to move away from the connector bridge 4 but is welded thereto and transfers the force or impact via the welding con^¬ nection to the connector bridge 4. Consequently, the connector bridge 4 is drawn or pulled out of its position on the second cover element 3b. Furthermore, mechanical stress or tension is applied on the welding connection. The connector bridge 4 is welded to the battery cells 2 and is therefore fixedly attached to the battery cell assembly 1. However, a partial displacement of the connector bridge 4 can occur and cause deviations of the normal conditions of the electric connection between connector bridge 4 and first and second welding sections 5a, 5b.

With regard to Fig. 5, showing a detailed cross-sectional view of the connector element 5 and the connector bridge 4, the con^¬ nector bridge 4 is placed on the second cover element 3b and is laterally surrounded by a wall structure 7. At least partially, said wall structure 7 extends substantially perpendicular to a planar extension of the connector element 5. The welding spots 10 connect the connector element 5 to the connector bridge 4 and define a distance or a gap between them.

The connector bridge 4 has retaining elements in the form of lateral straps 9 on both sides which are in contact with the wall structure 7. Said straps 9 may be provided as an appendix or an additional forming of the connector bridge 4. Further the straps are arranged integral to the connector bridge 4 and ex^¬ tend inclined in an upward direction. Thus, said straps 9 are arranged angularly relative to the connector bridge 4. In other words, the straps 9 are inclined in an opposite direction of the mounting direction of the connector bridge 4. Thus, said straps 9 act as a counter-structure for the spring-back force. In the case where the spring-back force affects the connector bridge 4, the straps 9 retain the connector bridge 4 in a direction that is opposite to the direction of the spring-back force.

In an alternative embodiment (which is not shown in the fig^¬ ures), it is also possible to arrange such retaining elements 9 on the end section 12 of the connector element 5 or on each of said first and second cover element 3a, 3b. In the former of these configurations, the connector element 5 is retained or supported against the spring-back force and relieves or unbur^¬ dens the welding connection between connector element 5 and connector bridge 4 from at least a part of the stress which results from the spring-back force. In a latter of these configurations, either the connector element 5 or the connector bridge 4 is retained in its position by the retaining elements 9.

Fig. 6 shows a side view of a battery cell assembly 1 with con^¬ nector element 5 and circuit board 6. The welding sections 14a, 14b of the connector bridge 4 are welded to respective welding sections of the battery cells 2 (not visible) . Specific connec^¬ tion portions 15 are provided on the connector bridges 4, 4a to 4f for the contact of the connector bridges 4, 4a to 4f to the respective connector elements 5. Some of the connection portions 15 are covered by the welding sections of the connector elements 5 and therefore not visible in this view.

Fig. 7 shows a detailed view of the welding sections 14a, 14b of the connector bridge 4. The welding sections 14a, 14b are sepa- rated by the recess 8 from each other. For example, the first welding section 14a is connected to a positive or plus pole of a battery cell 2 and the second welding section 14b is connected to a negative or minus pole of a battery cell 2. In the welding process, a welding current is provided which goes from one weld- ing section 14a or 14b to the battery cell 2 and from there to the other welding section 14a or 14b. Because of the welding current, the welding sections 14a, 14b are heated up and the welding geometries are welded together. The recess 8 ensures that the welding current goes from the welding section to the battery cell 2 and prevents that the welding current goes only from one welding section 14a, 14b to the other without flowing through the battery cell part. The wall structure 7 encloses the welding sections 14a, 14b on three sides in the shape of a U. Each of the welding sections

14a, 14b comprises one retaining element 9, which can be a strap which abuts to the wall structure 7. When the connector bridge 4 is inserted into its position be^¬ tween the wall structure 7, the straps 9 fix the welding sec^¬ tions 14a, 14b in their position in a defined distance to the wall structure 7 and the welding process can be carried out on the connector bridge 4. Further, the connector bridge 4 is se- cured within its position between the wall structure 7 in the case of an impact, e.g. when the battery pack where the battery cell assembly 1 is built-in, falls to the ground. Then, the stress or impact which affects the welding connection between connector bridge 4 and battery cell 2 can be absorbed or reduced at least partially by the straps 9. Further, the straps 9 retain the connector bridge 4 against a spring-back force transferred by a connector element 5 as explained above. In other words the straps 9 act as a barbed hook for the connector bridge 4. After the mounting and welding processes for mounting the connector bridges 4, 4a to 4f and the connector elements 5 to the battery cell assembly 1, the areas inside of the wall structure 7 can be filled up with resin or synthetic material for encapsu^¬ lating the electric connections formed by said components. Thus, wall structure 7 and resin or synthetic material form an enclo^¬ sure for the electric connections formed therein.

Fig. 8 shows a top view of a connector element 5 welded to a connector bridge 4 in an installed position on a cover element 3a, 3b. The connector bridge 4 has a T-shaped form and is placed lying flatly inside of a wall structure 7 that surrounds the connector bridge 4. Each end of the cross-bar of the T-shaped body of the connector bridge 4 has a first welding section 14a and a second welding section 14b which are separated from each other by a recess 8. Also the end section 12 of the connector element 5 has two weld- ing sections. Welding points 10 are provided on the end section 12 of the connector element 5 and on the two ends of the cross^¬ bar of the T-shaped body of the connector bridge 4.

The end portion of the connector bridge 4 which is connected to the end section 12 of the connector element 5 can have a recess 8 or can be provided without a recess. Further, the end section 12 of the connector element 5 and/or the end portion of the connector bridge 4 can have one or more retaining elements. In this view, the end portion of the connector bridge 4 has two retaining elements 9a abutting to the wall structure 7, wherein the end section 12 can also have retaining elements, also abut^¬ ting to the wall structure 7. Because of the spring-back resil^¬ ience of the connector element 5, the end section 12 tends to move away and out of the circumferential wall structure 7. The retaining elements impede a movement of the end section 12 out of its position within the wall structure 7.

Due to the tension applied by the end section 12 of the connec- tor element 5 via the welding connection, the end portion of the connector bridge 4 is drawn out of its position within the wall structure 7. The retaining elements 9a impede or counteract this movement . The end portions of the cross-bar of the T-shaped connector bridge 5 each have a recess 8 and welding sections 14a, 14b. The welding section 14b which is the welding section directed towards the connector element 5 has a retaining element 9c that abuts to the wall structure 7. The welding section 14a which is the welding section averted from the connector element 5 is retained in its position by a retaining element 9d that is pro^¬ vided on the wall structure 7 itself, e.g. which is formed inte^¬ grally to the wall structure 7. For example, two retaining elements 9d can be provided on the wall structure 7 for retaining the welding sections 14a, 14b of the connector bridge 4, whereas on the opposing side of the welding section 14a, 14b retaining elements 9c are formed inte- grally to the connector bridge 4.

Fig. 9 shows a sectional view B-B of the connector bridge 4 as indicated in Fig. 8. The welding section 14b comprises a retaining element 9c in the form of a strap which is inclined relative to the wall structure 7. On the side of the welding section 14a the wall structure 7 comprises a retaining element 9d in the form of a protrusion.

Both welding sections 14a, 14b are in contact with the battery cell 2 via the welding points 10 and partially distanced from the battery cell 2. In the case that the connector element 5 ap^¬ plies a force to the connector bridge 4 according to the con^¬ figuration as shown in Fig. 8, the welding sections 14a, 14b experience some kind of rotational force or torque. In such a situation, the retaining element 9c acts in a direction opposing to this rotational force and as a result, the connector bridge 4 is held in position.

For the installation of the connector bridge 4, the connector bridge 4 is laid into the wall structure 7, first with its weld^¬ ing section 14a which is moved in between the battery cell 2 and the retaining element 9d. After that the connector bridge is ro^¬ tated in between the wall structure, such that the retaining el^¬ ement 9c gets in contact with the wall structure 7 and the con^¬ nector bridge is positioned parallel to the battery cell 2.

Fig. 10 shows a top view of a connector element 5 welded to a connector bridge 4 having a different configuration of retaining elements 9a to 9d. The connection of the connector element 5 to the connector bridge 4 is configured similar to the connection as shown before. However, the wall structure 7 comprises four retaining elements 9d formed integrally thereto. Each retaining element 9d is provided for holding or retaining one welding section 14a, 14b. Fig. 11 shows a sectional view C-C of the connector bridge 4 as indicated in Fig. 10. In this configuration, the wall structure 7 has two retaining elements 9d formed on opposing sides of the wall structure. Each one of the retaining elements 9d holds or retains one of the welding sections 14a, 14b.

In an alternative embodiment retaining elements 9d, for example ribs, can be provided on the wall structure 7, wherein retaining elements 9a, for example straps, can be provided on the connec^¬ tor elements 5 and/or on the connector bridges 4. The retaining elements 9a on the connector elements 5 and/or on the connector bridges 4 can be snapped in under the retaining elements 9d on the wall structure 7. In such a configuration, the retaining el- ements 9d on the wall structure 7 can hold back or retain the retaining elements 9a on the connector elements 5 and/or on the connector bridges 4.

Fig. 12 shows a sectional view D-D of the connector bridge 4 as indicated in Fig. 10. Also in this configuration two retaining elements 9d are formed to opposing sides of the wall structure 7. However, cutouts 16 are provided between the retaining elements 9d and the battery cell 2. In both configurations, for in^¬ stallation, the connector bridge 4 can be snapped into the ge- ometry of the wall structure 7, i.e. the retaining elements 9d form a catch for the welding sections 14a, 14b which can be pressed together due to the recess 8 formed between them. Thus, a snap connection for the connector bridge 4 is established with the wall structure 7.

In general, the retaining elements 9, 9a, 9c, 9d can be provided advantageously in an adapted manner to the desired configuration of the battery cell assembly 1. In particular, the retaining elements 9, 9a, 9c, 9d can be arranged alone or in plurality on the connector bridges 4, 4a, 4b, 4c, 4d, 4e, 4f, and in particu^¬ lar on the end sections of the I-shaped, H-shaped, L-shaped or T-shaped connector bridges, on the connector elements 5 or on the wall structure 7. List of reference numerals

1 battery cell assembly

2 battery cell

3a first cover element

3b second cover element

4, 4a, 4b, 4c, 4d, 4e, 4f connector bridges

5 connector elements

5a first welding section

5b second welding section

6 circuit board

7 wall structure

8 recess

9, 9a, 9c, 9d retaining element

10 welding points

11 middle section of connector element 12 end section of connector element 13 bending line

14a first welding section of connector bridge

14b second welding section of connector bridge

15 connection portion

16 cutout

Claims

1. Battery pack with a battery cell assembly (1) comprising:

- at least one first component (4 or 5) being a connector component ;

- at least one second component (2 or 4), wherein said first connector component (4 or 5) is in electrical contact with said second component (2 or 4);

- at least one wall structure (7) which is arranged adjacent to said first connector component (4 or 5) and said second component (2 or 4) ;

- and at least one retaining element (9) which is provided on said first connector component (4 or 5) and/or on said second component (2 or 4) and/or on said wall structure (7), wherein said retaining element (9) fixes said first connec^¬ tor component (4 or 5) and/or said second component (2 or 4) in its position relative to said wall structure (7) .

2. Battery pack according to claim 1, characterized in that

said first component (4 or 5) is fixedly attached to said second component (2 or 4) .

3. Battery pack according to claim 1 or 2, characterized in

that said first component is a connector bridge (4, 4a, 4b, 4c, 4d, 4e, 4f) and that said second component is a battery cell (2) .

4. Battery pack according to claim 1 or 2, characterized in

that said first component is a connector element (5) and that said second component is a connector bridge (4, 4a, 4b, 4c, 4d, 4e, 4f) .

5. Battery pack according to any of the preceding claims,

characterized in that said wall structure (7) is arranged substantially perpendicular to a planar extension of said first component (4, 5) .

6. Battery pack according to any of the preceding claims, characterized in that said first component (4 or 5) has at least one fixing section (5a, 5b, 14a, 14b) and that said first component (4 or 5) is connected to said second compo^¬ nent via at least one fixing connection.

7. Battery pack according to claim 6, characterized in that said wall structure (7) is formed substantially U-shaped, wherein said fixing section (5a, 5b, 14a, 14b) is formed correspondingly to the shape of said wall structure (7) and is at least partially surrounded by said wall structure

(7) .

8. Battery pack according to claims 6 or 7, characterized in that said fixing section (5a, 5b, 14a, 14b) is a welding section and that said first component (4 or 5) is connected to said second component via at least one welding connec^¬ tion .

9. Battery pack according to any of claims 6-8, characterized in that said first component (4 or 5) has at least one, preferably two, retaining elements (9), preferably formed integrally to said first component (4 or 5), in particular two retaining elements (9) arranged on opposing sides of said fixing section (5a, 5b, 14a, 14b) of said first con^¬ nector component (4 or 5), wherein each of said two retaining elements (9) abuts on a different wall of said wall structure ( 7 ) .

10. Battery pack according to claim 9, characterized in that said at least one, preferably two, retaining elements (9) abut inclined on said wall structure (7) or in that said at least one, preferably two, retaining elements (9) are ar^¬ ranged angularly relative to said wall structure (7) .

Battery pack according to claim 3 or any of claims 5 to 10 referring back to claim 3, characterized in that at least one connector element (5) is fixed, preferably welded, to said connector bridge (4, 4a, 4b, 4c, 4d, 4e, 4f ) , wherein said connector element (5) provides a first force loaded on said connector bridge (4, 4a, 4b, 4c, 4d, 4e, 4f ) , said first force drawing said connector bridge (4, 4a, 4b, 4c, 4d, 4e, 4f) out of its intended position, wherein said at least one retaining element (9) clamps in a force closure providing a second force in an opposing direction to said first force provided by said connector element (5) .

12. Battery pack according to any of claims 6 to 10 referring back to claim 4, characterized in that a resilient force affects said connector element (5) loading a stress on said fixing connection, wherein said at least one retaining element (9) clamps in a force closure to said wall structure

(7) and provides a force affecting in an opposing direction to said stress on said fixing connection.

13. Battery pack according to claim 6 to 12 referring back to claim 4, characterized in that said fixing section is a welding section, which comprises at least one first welding section (5a, 14a) and at least one second welding section

(5b, 14b), wherein said first welding section (5a, 14a) is separated from said second welding section (5b, 14b) by a recess (8) and wherein at least one retaining element (9) is arranged on each of said first and second welding section

(5a, 14a, 5b, 14b) .

14. Battery pack according to one of the claims 3 to 13, characterized in that said connector bridge (4, 4a, 4b, 4c, 4d, 4e, 4f) has a H-shaped form or a T-shaped form or an L- shaped form or an I-shaped form, wherein said at least one, preferably two, retaining element (9) is arranged on at least one end section of a leg of said H-shaped form or at least one end section of a cross bar of said T-shaped form or at least one end section of a leg of said L-shaped form or at least one end section of said I-shaped form, in par- ticular wherein at least one, preferably two, retaining el^¬ ement (9) is arranged on each end section of each leg of said H-shaped form or on each end section of the cross bar of said T-shaped form or on each end section of each leg of said L-shaped form or on each end section of said I-shaped form.

15. Battery pack according to any of the preceding claims,

characterized in that said first component (4 or 5) com^¬ prises at least one pair of retaining elements (9) which forms a pair of barbed hooks providing resistance against movement of said first component (4 or 5) .

16. Battery pack according to claim 3 or one of the preceding claims referred back to claim 3, characterized in that said connector bridge (4, 4a, 4b, 4c, 4d, 4d, 4e, 4f) comprises at least one first retaining element (9c) and said wall structure (7) comprises at least one second retaining ele^¬ ment (9d), wherein said first retaining element (9c) and said second retaining element (9d) are arranged on opposing sides of said connector bridge (4, 4a, 4b, 4c, 4d, 4d, 4e, 4f) .

17. Battery pack according to claim 16, characterized in that said first retaining element (9c) is arranged inclined rel^¬ ative to said wall structure (9d) and that said second re^¬ taining element (9d) is arranged substantially perpendicu^¬ lar to said wall structure (7) .

18. Battery pack according to any of the preceding claims,

characterized in that said wall structure (7) comprises two retaining elements (9d) on opposing sides of said first component (4 or 5), wherein said first component (4 or 5) comprises at least one recess (8) which divides said first component into a first fixing section (5a, 14a) and a sec^¬ ond fixing section (5b, 14b) in the region of said retaining elements (9d) in such a way, that said first fixing section (5a, 14a) and said second fixing section (5b, 14b) can snap into the geometry formed by the wall structure (7) and the retaining elements (9d) .

19. Battery pack according to claim 18, characterized in that the wall structure (7) has at least one cutout (16) adja^¬ cent to each of said retaining elements (16) .

20. Battery pack according to any of the preceding claims,

characterized in that at least one battery cell (2) is electrically connected via said first component (4 or 5) and/or via said second component (2 or 4) to at least one terminal unit of said battery cell assembly (1) .

21. Rechargeable battery, comprising at least one battery pack according to one of the claims 1 to 20.

22. Handheld garden tool such as a hedge trimmer, a blower, a brush cutter or a chainsaw, comprising at least one rechargeable battery pack having at least one battery pack according to one of the claims 1 to 20.