RECHARGEABLE BATTERY PACK

Abstract

A rechargeable battery pack. The rechargeable battery pack includes a housing, at least one rechargeable battery cell including a cell connector, and a circuit board. The at least one rechargeable battery cell being electrically connected to the circuit board via the cell connector. The circuit board includes a connection point for the materially bonded connection of the cell connector to the circuit board, the connection point being situated on a side of the circuit board facing away from the rechargeable battery cells.

Claims

1-15. (canceled)

16. A rechargeable battery pack, comprising: a housing; at least one rechargeable battery cell; a cell connector; and a circuit board, the at least one rechargeable battery cell being electrically connected to the circuit board via the cell connector, wherein the circuit board includes a connection point for a materially bonded connection of the cell connector to the circuit board, the connection point being situated on a side of the circuit board facing away from the rechargeable battery cells.

17. The rechargeable battery pack as recited in claim 16, wherein the rechargeable battery pack includes a mounting aid for mounting support.

18. The rechargeable battery pack as recited in claim 17, wherein the circuit board includes a recess, in which the mounting aid and the cell connector are situated, the mounting aid having a length that is greater than a thickness of the circuit board.

19. The rechargeable battery pack as recited in claim 17, wherein the mounting aid has a rounded edge on a side facing away from the connection point, which is provided for flexing the cell connector.

20. The rechargeable battery pack as recited in claim 16, wherein the rechargeable battery pack includes a support element, on which the circuit board rests in an area of the connection point.

21. The rechargeable battery pack as recited in claim 16, wherein the circuit board includes a contact surface, which is connected via a material bonding, via a solder layer, to a weld platelet in a materially bonded manner.

22. The rechargeable battery pack as recited in claim 21, wherein a dimple of the cell connector, is connected directly to the weld platelet.

23. The rechargeable battery pack as recited in claim 21, wherein the material bonding and/or the contact surface and/or the weld metal plate, includes a recess.

24. The rechargeable battery pack as recited in claim 21, wherein the weld metal platelet includes a dimple, which extends in a direction facing away from the circuit board.

25. The rechargeable battery pack as recited in claim 24, wherein the recess is situated in a weld area in an area of the dimple.

26. The rechargeable battery pack as recited in claim 21, wherein the material bonding and/or the contact surface includes at least one degassing channel for an expansion of trapped air.

27. A method for welding a cell connector on a circuit board, the method comprising: welding the cell connector via a weld platelet, onto a contact surface of the circuit board; wherein a cavity is situated in a direct weld area between the weld platelet and the circuit board.

28. The method as recited in claim 27, wherein the weld platelet is connected via a solder layer, to the circuit board and the solder layer and/or the contact surface and/or the weld metal platelet includes a recess.

29. The method as recited in claim 27, wherein the welding takes place via a resistance welding method or a laser welding method.

30. The method as recited in claim 27, wherein the contact surface is a metallization in an outer layer of the circuit board.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further advantages result from the following drawing description. The figures and the description contain numerous features in combination. Those skilled in the art will also appropriately consider the features individually and combine them to form meaningful further combinations. Reference numerals of features of different specific embodiments of the present invention, which essentially correspond to one another, are provided with the same number and with a letter characterizing the specific embodiment.

[0039] FIG. 1 shows a perspective view of an electric bicycle including a rechargeable battery pack according to an example embodiment of the present invention,

[0040] FIG. 2 shows a perspective view of the rechargeable battery pack without the housing, according to an example embodiment of the present invention.

[0041] FIG. 3 shows a front view of a cell holder including inserted rechargeable battery cells of the rechargeable battery pack, according to an example embodiment of the present invention.

[0042] FIG. 4 shows a section through a connection point of the rechargeable battery pack, according to an example embodiment of the present invention.

[0043] FIG. 5A schematically shows a side view of the connection point according to FIG. 4.

[0044] FIG. 5B schematically shows a top view of the connection point according to FIG. 4.

[0045] FIG. 6A schematically shows a side view of an alternative specific embodiment of a connection point for a rechargeable battery pack.

[0046] FIG. 6B schematically shows a top view of the connection point according to FIG. 6A.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0047] A consumer 10 including a rechargeable battery pack 100 is shown in a schematic side view in FIG. 1. Consumer 10 is designed by way of example as an electrically driven means of transportation 12, in particular, as an electric bicycle 14. Electric bicycle 14 may, for example, be designed as a Pedelec or as an eBike.

[0048] Electric bicycle 14 includes a housing 16 in the shape of a frame 18 or of a bicycle frame. Two wheels 20 are connected to frame 18. Consumer 10 also includes a drive unit 22, which includes an electric motor or auxiliary motor. The electric motor is designed preferably as a permanent magnet-excited, brushless DC motor. The electric motor is designed, for example, as a mid-mounted motor, a hub motor or the like also being possible.

[0049] Drive unit 22 includes a control unit (not shown), which is designed for controlling or regulating electric bicycle 14, in particular, the electric motor. Electric bicycle 14 includes a pedal crank 24. Pedal crank 24 includes a pedal crankshaft (not shown).

[0050] The control unit and drive unit 22 including the electric motor and the pedal crankshaft are situated in a drive housing 26 connected to the frame. The drive motion of the electric motor is preferably transferred via a gear (not shown) to the pedal crankshaft, the amount of assistance by drive unit 22 being controlled or regulated with the aid of the control unit.

[0051] Consumer 10 is electrically and mechanically connected to rechargeable battery pack 100, which is designed for supplying power to drive unit 22. Rechargeable battery pack 100 is designed as a removable rechargeable battery pack 102. The underside of frame 18 includes an opening, through which rechargeable battery pack 100 is inserted or pivoted into frame 18. In the connected state, the opening is closed by a housing 104 of rechargeable battery pack 100. Alternatively, it is possible that frame 18 itself closes the opening or the opening is closed by a cover. Alternatively, it is possible that rechargeable battery pack 100 is designed to be detachable at frame 18 or to be attachable at a luggage carrier not shown. Alternatively, rechargeable battery pack 100 may also be inserted from above or laterally. In addition, it is also possible that rechargeable battery pack 100 is inserted from below into a closed frame tube.

[0052] Rechargeable battery pack 100 is shown in a perspective view in FIG. 2 without housing 104 of rechargeable battery pack 100. Housing 104 seals rechargeable battery pack 100 to the outside and is formed of a synthetic material. For detachable connection, rechargeable battery pack 110 includes a mechanical interface not shown, via which rechargeable battery pack 100 is lockable on electric bicycle 14.

[0053] Rechargeable battery pack 100 includes, for example, 20 rechargeable battery cells 106 (see FIG. 3), which are situated in the interior of housing 104. Housing 104 also includes interior housing parts 108 in the form of cell holders 110. Cell holders 110 are designed to accommodate rechargeable battery cells 106. Rechargeable battery pack 100 includes by way of example four cell holders 110, in each of which five rechargeable battery cells 106 are situated. Cell holders 110 have a multi-part design, for example, the parts being connected to one another in a force-fitting and form-fitting manner. It is also possible, however, that cell holders 110 are designed as one part or as one piece. Cell holders 110 are situated behind one another in such a way that rechargeable battery cells 106 accommodated in different cell holders 110 are situated essentially coaxially to one another.

[0054] Rechargeable battery cells 106 are designed as cylindrical round cells. Rechargeable battery cells 106 are situated essentially completely in cell holders 110. Cell holders 110 in this case enclose rechargeable battery cells 106 essentially completely along their lateral surface. Rechargeable battery cells 106 have a center axis 107 (see FIG. 3), which corresponds to a center longitudinal axis of rechargeable battery cells 106. Within a cell holder 110, rechargeable battery cells 106 are situated next to one another so that center axes 107 of rechargeable battery cells 106 are situated in parallel to one another.

[0055] Rechargeable battery pack 100 includes electronics 112, which are designed for controlling or regulating rechargeable battery pack 100 and/or consumer 10 and/or a charging device not shown. Electronics 112 include by way of example a BMS for monitoring rechargeable battery pack 100.

[0056] Electronics 112 include a circuit board 114, which is designed by way of example as a planar and rigid circuit board 114. Circuit board 114 is situated on cell holder 110 and is seated on cell holder 110. Circuit board 114 has a length that corresponds essentially to a length of cell holder 110.

[0057] Cell holder 110 and circuit board 114 include connection elements not shown for force-fitting and/or form-fitting connection. Circuit board 114 spans a circuit board plane 115. Circuit board 114 or circuit board plane 115 (see FIG. 3) extends in parallel to rechargeable battery cells 106 or to center axes 107 of rechargeable battery cells 106.

[0058] Rechargeable battery pack 100 includes cell connector 118, which is designed for electrically connecting rechargeable battery cells 106 to electronics 112. Cell connectors 118 are designed for providing power and/or for monitoring the individual cell voltage. Cell connector 118 is made of a metallic material, for example, of a steel such as hilumin. In the specific embodiment shown, all cell connectors 118 are connected directly to circuit board 114. Alternatively, it would also be possible that individual cell connectors 118, for example, the cell connector for supplying power, are connected directly to electrical contact elements (not shown) of rechargeable battery pack 100.

[0059] Cell connectors 118 are designed by way of example as one piece. Cell connectors 118 include a circuit board connection element 120 for connection to circuit board 114 and a cell connection element 122 (see FIG. 3) for connection to rechargeable battery cells 106.

[0060] Circuit board 114 has an upper side 124, which faces away from rechargeable battery cells 106, and a lower side 125, which faces rechargeable battery cells 106. Connection points 126, via which cell connector 118, in particular, circuit board connection element 120, is connected in a materially bonded manner to circuit board 114, for example, via a weld connection, are situated on upper side 124 of circuit board 114. Circuit board 114 has a recess 128, through which cell connectors 118 are guidable to upper side 124 of circuit board 114.

[0061] A top view of one of cell holders 110 including inserted rechargeable battery cells 106 is shown in FIG. 3. Two cell connectors 118 are shown by way of example, which are designed for individual cell monitoring and are connected to circuit board 114. Cell connectors 118 are also designed to connect rechargeable battery cells 106 serially and/or in parallel to one another. Cell connectors 118 are connected to rechargeable battery cells 106, in particular, to respective cell poles 130 of rechargeable battery cells 106, via cell connection element 122 with the aid of a resistance welding connection. Thus, cell connection elements 122 extend essentially in parallel to cell poles 130 of rechargeable battery cells 106. Cell poles 130 of rechargeable battery cells 106 are situated essentially perpendicular to circuit board plane 115.

[0062] Cell holder 110 includes one individual cell receptacle 132 per rechargeable battery cell 106. Individual cell receptacles 132 include a cylindrical wall 134, which encloses rechargeable battery cells 106 along their lateral surface. Wall 134 is designed in such a way that it is assigned to two different individual cell receptacles 132 between two adjacent rechargeable battery cells 106. Wall 134 is rigid and is formed, for example, from a hard plastic. For play-free fastening of rechargeable battery cells 106, individual cell receptacles 132 include fastening means (i.e., fastener) 136 for radially fixing rechargeable battery cells 106 in individual cell receptacles 132. Fastening means 136 are designed, for example, as resilient latch arms, which apply a force to the lateral surface of rechargeable battery cells 106 in the connected state. Fastening means 136 and cylindrical wall 134 are designed by way of example as one piece with cell holder 110.

[0063] Individual cell receptacles 132 each have a center axis 138, which corresponds essentially to center axis 107 of rechargeable battery cells 106. In this case, center axis 107 of rechargeable battery cells 106 may have a slight offset from the center axis of individual cell receptacles 132 as a function of the size of the cell.

[0064] The geometry of rechargeable battery pack 100 is determined largely by the arrangement of individual cell receptacles 132 to one another. A compact and flexible rechargeable battery pack 100 installable in consumer 10 may be provided as a result of the design of cell holder 110 described below.

[0065] Rechargeable battery cells 106 are distributed on two main planes 140 and on one intermediate plane 142, which are situated in parallel to one another. Cell holder 110 includes two individual cell receptacles 132, which are situated in first main plane 144, and two individual cell receptacles 132, which are situated in second main plane 146. Main planes 140 each include more individual cell receptacles 132 than intermediate plane 142. Situated between main planes 140 is intermediate plane 142, in which a single individual cell receptacle 132 is situated. Main planes 140 and intermediate planes 142 each extend through center axes 138 of individual cell receptacles 132, to which they are assigned.

[0066] Individual cell receptacles 132 are situated in such a way that a distance 150 between first or second main planes 144, 146 and intermediate plane 142 is in a range between 54% and 60% of a diameter 152 of rechargeable battery cells 106. Diameter 152 of rechargeable battery cells 106 in this case corresponds essentially to a diameter of individual cell receptacles 132. Distance 150 between first main plane 144 and intermediate plane 142 and distance 150 between second main plane 146 and intermediate plane 142 are, for example, essentially the same.

[0067] Circuit board 114 of rechargeable battery pack 100 is situated essentially in parallel to main planes 140. Distance 154 of two adjacent center axes 138 of individual cell receptacles 132 within a main plane 140 is designed to be greater in this case than a width 156 of circuit board 114, in particular, by more than 75% greater than width 156 of circuit board 114. Distance 154 of rechargeable battery cells 106 in main planes 140 is designed, for example, to be the same. It would, however, also be possible that different main planes have different distances between their assigned individual cell receptacles.

[0068] Cell holder 110 spans a circuit board accommodation area 158, which is designed for accommodating circuit board 114, circuit board 114 being situated completely in circuit board accommodation area 158. Circuit board accommodation area 158 is situated above individual cell receptacle 132 of intermediate plane 142 and between the two individual cell receptacles 132 of first main plane 144. As a result, the circuit board is situated in such a way that circuit board plane 115 has a distance 159 from first main plane 144, which is in a range between 30% and 55% of diameter 152 of rechargeable battery cells 106 or of individual cell receptacles 132, as a result of which rechargeable battery pack 100 is particularly compactly designed.

[0069] A section through a connection point 126 is shown in FIG. 4, via which cell connector 118 is connected to circuit board 114.

[0070] Prior to mounting, cell connector 118 extends essentially completely in one plane. Circuit board connection element 120 thus extends prior to mounting as an extension in a straight line starting from cell connection element 122 in the direction of circuit board 114.

[0071] Since connection point 126 is situated on a side facing away from rechargeable battery cells 106, cell connector 110, in particular, circuit board connection element 120, is fed through recess 128 of circuit board 114, so that circuit board connection element 120 protrudes on the upper side of circuit board 114.

[0072] Cell holder 110 includes a mounting aid 160, which is situated in recess 128 of circuit board 114. Mounting aid 160 has a length, which is greater than a thickness of circuit board 114, so that mounting aid 160 protrudes on the upper side of circuit board 114. Mounting aid 160 has a rounded edge 162, which is situated on a side facing away from connection point 126. Cell connector 118 is also situated on the side of mounting aid 160, which faces away from connection point 126.

[0073] For better illustration, connection 126 is shown in a schematic side view and in a schematic top view in FIG. 5A and in FIG. 5B.

[0074] Connection point 126 includes a contact surface 164. Contact surface 164 is designed by way of example as a copper pad on the outer layer of circuit board 114. Contact surface 164 is connected via a solder layer 166 to a weld platelet 168 with the aid of a solder connection. Weld platelet 168 is made of a metallic material. For example, weld platelet 168 is made of the same material as cell connector 118. It is, however, also possible that weld platelet 168 is made of another material.

[0075] Weld platelet 168 extends in parallel to circuit board plane 115 (see FIG. 3). To connect cell connector 118 to connection point 126 of circuit board 114, in particular, to connect circuit board connection element 120 to weld platelet 168, circuit board connection element 120 is flexed in the area of rounded edge 162 of mounting aid 160 around the latter and guided above connection point 126. Mounting aid 160 ends approximately at the height of weld platelet 168, so that circuit board connection element 120 in the mounted state rests on mounting aid 160 and on weld platelet 168.

[0076] The connection of circuit board connection element 120 to weld platelet 168 takes place via a resistance welding method. For this purpose, circuit board connection element 120 is brought into contact with weld platelet 168. The resistance welding takes place via two electrodes, between which a voltage is applied. In the specific embodiment shown, one electrode is placed on cell connector 118 above connection point 126 and the second electrode is placed directly on weld platelet 168.

[0077] Alternatively, it would also be possible that cell connector 118 includes two circuit board connection elements 120, which extend via a gap separately and in parallel to one another, and in each case an electrode is placed on a circuit board connection element 120 in such a way that the gap is situated between the electrodes.

[0078] Since the connection also takes place by application of force on circuit board 114 in the area of connection point 126, rechargeable battery pack 100 includes, in particular, cell holder 110, a support element 170, on which circuit board 114 rests in the area of connection point 126 and is supported thereby. Thus, support element 170 is designed both as a mounting stop for aligning circuit board 114 and as a counter bearing during the welding process. Mounting aid 160 and support element 170 are designed by way of example as one piece with cell holder 110.

[0079] Cell connector 118, in particular, circuit board connection element 120, includes a dimple 172, via which the bearing surface of cell connector 118 [that bears] on weld platelet 168 is reduced. Dimple 172 of cell connector 118 in this case extends in the direction of circuit board 114. The energy or heat required for welding is introduced essentially in the area of dimple 172. This area thus corresponds to a direct weld area 174.

[0080] Connection point 126 includes a cavity 176 in direct weld area 174, which is designed to locally reduce the heat transfer during the welding process. Cavity 176 is formed between weld platelet 168 and circuit board 114.

[0081] Cavity 176 is formed in the specific embodiment shown by a recess 178 in contact surface 164 and a recess 180 in solder layer 166. Recesses 178, 180 have, by way of example, the same cross section, but it is also possible that recesses 178, 180 have different cross sections and thus different sizes. Recesses 178, 180, for example, have a rectangular cross section, however, other shapes such as, for example, square, round, triangular, polygonal, etc. are also possible.

[0082] An overheating in direct weld area 174 is thus prevented by cavity 176 and the heat is better distributed over entire weld area 182.

[0083] For the expansion of trapped air, circuit board 114 also includes degassing channels 186, which are designed by way of example as recesses in solder layer 166 and in contact surface 164.

[0084] An alternative specific embodiment of connection point 126 according to FIG. 4 is shown in FIG. 6A and FIG. 6B. Connection point 126a in this case differs, in particular, in that cavity 176a is situated only in solder layer 166a in the form of a recess 180a. Thus, cavity 176a is situated between weld platelet 168a and contact surface 164a. This cavity 176a is producible, for example, by inserting solder resist webs 184a, which delimit or form recess 180a.