Akkupack

Abstract

Battery pack (10) for an electrical device comprising at least one circuit board (12), at least one battery cell (16) and at least one temperature sensor (22) for measuring the temperature of at least one battery cell (16), wherein the temperature sensor (22) is attached directly to the circuit board (12), and wherein a section of the circuit board (12) forms a support element (18) to which the temperature sensor (22) is attached, characterized in that the support element is sectionally delimited from the rest of the circuit board by a groove-shaped recess.

Description

[0001] The invention relates to a battery pack and an electric hand tool in which a battery pack according to the invention can be used.

[0002] Battery packs are specifically designed to refer to rechargeable batteries for electrically powered devices. Such electrically powered devices include, for example, power tools, but also all conceivable other types of electrically powered devices, such as kitchen appliances, mobile work devices (mobile phones, tablets, laptops, etc.), and even mobile entertainment devices.

[0003] The use of battery packs is particularly advantageous when using electrically powered devices, especially handheld power tools, on construction sites, as no cables, and especially no extension cords, are required to supply the device with electrical power. Furthermore, the provision of electrical power on construction sites can be problematic, especially when multiple electrically powered devices, especially handheld power tools, are being operated simultaneously. Finally, with battery-powered handheld power tools, there is no risk of damaging the power cable while working.

[0004] A battery pack for an electrical device typically comprises at least one circuit board, at least one battery cell, and a temperature sensor. Typically, several battery cells are combined into battery packs that can be easily connected to the device. The circuit board can be designed to accommodate and be equipped with resistors, fuses, and electrical components for controlling the battery cells. The battery cells are connected to the circuit board via conductor tracks or printed circuit boards and can be connected in series and / or parallel.

[0005] Battery packs of this type can be coupled to a power tool, for example, to supply the power tool's electric motor with power when connected. Once a connected battery pack is discharged, it can be replaced with a charged one, or charging can be performed directly on the tool.

[0006] It is well known that both a battery's ability to be recharged and its ability to deliver power depend on its temperature. For example, if a battery pack is too cold, it can only deliver little or no power to the power tool. If the temperature is too high, its stored power capacity decreases. Furthermore, excessively high temperatures can lead to a dangerous condition inside the battery pack.

[0007] For this reason, it is desirable to be able to determine the temperature of a battery pack. The provision of a temperature sensor in a battery pack is known from various prior art documents.

[0008] For example, DE 42 34 231 A1 discloses a rechargeable battery with a temperature sensor that shuts off the battery when a predetermined temperature is reached. The battery then no longer supplies power, even though it is not yet fully discharged. Since there is no cooling time for the battery, it can be recharged immediately. Despite the shorter discharge time, the battery is intended to be available for a longer period of time. The temperature sensor is intended to determine the temperature of the battery cells.

[0009] Another solution is known from DE 90 16 987 U1, in which a metal clamp presses a temperature sensor against a battery. The metal clamp is attached at one end to a clamping claw by means of a clamping screw and a clamping nut. This clamp, in turn, is secured to a metal base plate.

[0010] Furthermore, it is known to place temperature sensors somewhere in the battery pack so that they are in contact with at least one cell wall, if possible. Since temperature sensors are conventionally inserted loosely into the battery pack, a small air gap always remains between the surface of the temperature sensor and the nearest cell. However, this method distorts the measured temperatures due to the air cushion between them.

[0011] In order to counteract this problem, a solution is described in the document EP 1 927 152 B1 in which a spring element is provided which loads the temperature sensor in the direction of at least one battery cell, wherein the spring element is connected to a cell holder for receiving and holding the battery cells and wherein the cell holder and spring element, the latter designed as a tab, are plastic parts.

[0012] Although this solution has proven advantageous in practice, assembly, like the other solutions described above, is comparatively complex. In particular, it is necessary to connect the temperature sensor to the circuit board. In prior art solutions, this is achieved, for example, by providing a connection via a stranded wire, a cable, or a connector. In all of these cases, however, the circuit board must be manually populated with the respective connecting elements, so this part of the assembly must be performed manually.

[0013] Finally, reference is made to the prior art documents DE 10 2016 107 780 A1, US 2015 / 0244040 A1 and US 2016 / 0204481 A1.

[0014] Accordingly, it is an object of the present invention to provide a battery pack which at least reduces the disadvantages known from the prior art and enables simplified assembly.

[0015] This object is achieved by a battery pack having the features of claim 1 and an electric hand tool having the features of claim 9.

[0016] Accordingly, the at least one temperature sensor is arranged on at least one circuit board and is attached directly to the circuit board, wherein a portion of the circuit board forms a carrier element to which the temperature sensor is attached.

[0017] In this case, the at least one circuit board to which the temperature sensor is directly attached forms, in particular, the main circuit board, which is equipped with the resistors, fuses, and / or electrical components for controlling the battery cells. In the case of multiple circuit boards, the information from the temperature sensor can thus be easily and directly transmitted to the processing electronics of the main circuit board.

[0018] By directly mounting the temperature sensor on the circuit board, the complex assembly of a connecting element, such as a stranded wire, a connecting wire or the like, as is known from the prior art, can be dispensed with.

[0019] In particular, the carrier element is formed integrally with the circuit board, i.e., the carrier element is part of the circuit board. According to the invention, a separate carrier element is dispensed with.

[0020] For example, a conventional printed circuit board can be provided with a support element by, for example, forming a section of the circuit board through a forming process or elastically deforming it, for example, by bending it, so that the support element or at least the temperature sensor attached to it, at least in the assembled state, extends in a plane that is not parallel to the rest of the circuit board. For example, the circuit board can be bent or bulged in the area of ​​the support element.

[0021] According to the invention, the carrier element is separated from the rest of the circuit board in sections by a groove-shaped recess. During the manufacture of the carrier element, for example, a groove-shaped milled recess can be made, which separates the carrier element at least in sections from the rest of the circuit board. The groove-shaped recess can describe a wide variety of curves in a plan view. For example, it can be provided that the carrier element is designed in a tab-shaped manner when viewed from above.

[0022] Regardless of whether the carrier element is separated from the rest of the circuit board in sections by a groove-shaped recess and / or extends, for example by bending, in a different plane than the rest of the circuit board, it can also be provided that the circuit board is designed to be elastic at least in the region of the carrier element in order to be able to elastically prestress the temperature sensor in the direction of at least one battery cell.

[0023] For example, a tab-shaped support element - but also any other shaped or provided support element - can be deflected by a predetermined angle relative to the rest of the circuit board, wherein the angle is selected such that, in the assembled state, the support element would engage in the installation space of at least one battery cell. Due to the partially elastic design of the support element, however, it can be elastically deflected by the corresponding at least one battery cell during assembly and in this way elastically preloads the temperature sensor against the at least one battery cell. Such a solution combines, for example, the advantages of a spring element, as known, for example, from EP 1 927 152 B1, with the inventive advantage of being able to dispense with an additional connecting element, such as a stranded wire, a plug, or a connecting wire.

[0024] The at least one temperature sensor can be arranged, regardless of the specific design of the carrier element, on a side of the circuit board facing the at least one battery cell or alternatively on a side of the circuit board facing away therefrom.

[0025] It can further be provided that the battery pack comprises a cell holder and / or a housing, wherein a holding structure is provided on the cell holder or the housing, which, when mounted, holds the temperature sensor attached to the circuit board in contact with at least one battery cell. For example, with an elastic design of the circuit board, a corresponding deflection of the carrier element toward at least one battery cell can be effected by the holding structure, at least in the region of the carrier element.

[0026] Alternatively, however, it is of course also conceivable that the circuit board has already been correspondingly formed in the area of ​​the carrier element and the holding structure only serves to ensure contact between the temperature sensor attached to the circuit board and at least one battery cell.

[0027] In particular, it can be provided that the holding structure comprises a snap hook which, in the assembled state, engages behind the carrier element and holds it in the desired position.

[0028] Alternatively or additionally, it can be provided that the holding structure comprises a hold-down device which, in the assembled state, presses the carrier element towards at least one battery cell and holds it in the desired position. Such a hold-down device can be designed in particular as a projection, for example dome-shaped, and can extend, for example, from a housing shell which is attached to the side of the circuit board facing away from the battery cells, towards the battery cells. A holding structure designed as a snap hook can, for example, be formed on the cell carrier in order to engage behind the carrier element during assembly and to fix it in the desired position in the assembled state.

[0029] Finally, the invention relates to an electric hand tool with a battery pack as described above for supplying an electric motor of the electric hand tool with electrical energy, wherein the battery pack can be detachably coupled to the electric hand tool.

[0030] Further advantages and features of the invention emerge from the remaining application documents, in particular from the description of the figures and the dependent claims.

[0031] The invention is explained in more detail below with reference to the figures. The figures show preferred embodiments of the invention in which various features of the invention are combined. Of course, however, these features can also be considered separately, and those skilled in the art will be able to combine them into suitable sub-combinations without inventive effort.

[0032] The figures show schematically: Fig. 1 shows a battery pack according to a first embodiment in a perspective view; Fig. 2 the battery pack according to Fig. 1 in partially sectioned side view; Fig. 3 a plan view of a battery pack according to the invention with a lid; Fig. 4 the battery pack according to Fig. 3 in a sectional view along the line BB; and Fig. 5 the detail C from Fig. 4; and Fig. 6 an isometric view of a battery pack according to the invention according to another embodiment of the invention.

[0033] The Fig. Figure 1 shows a battery pack, generally designated by reference numeral 10. For simplicity, the outer battery housing surrounding the battery pack 10 is not shown in this illustration. The battery pack 10 comprises a circuit board 12, a cell holder 14, and three battery cells 16.

[0034] Of course, a battery pack within the meaning of the present invention can also have more than three battery cells, for example eight battery cells, four battery cells, or fewer battery cells, for example one or two battery cells. Furthermore, it is conceivable for more than one circuit board to be provided, wherein a single circuit board is advantageous for the purposes of particularly simple assembly. Furthermore, the illustrated embodiment of a cell holder 14 is only an example; other designs, such as those known from EP 1 927 152 B1, are also conceivable. It is also irrelevant for the invention whether the battery cells are connected in parallel or in series and, in particular, also irrelevant whether the battery cells are arranged in one plane or in several planes one above the other.

[0035] The battery cells 16 are accommodated in the cell holder 14 in such a way that short circuits, as well as mechanical damage to the electrical contacts and the battery cells 16 themselves, are avoided. Furthermore, the cell holder 14 has connecting elements (not labeled) that serve to connect to housing parts of the housing 30 of the battery pack 10.

[0036] The printed circuit board 12 comprises a carrier element 18 formed integrally with it, which is formed by a section of the printed circuit board. In the first embodiment, the carrier element 18 is separated from the remaining part of the printed circuit board 12 by a straight milled recess 20 and is designed in the form of a tab or tongue. Furthermore, the Fig. 2 that the carrier element 18 extends in a different plane than the rest of the circuit board 12. The carrier element 18 and the circuit board 12 enclose an angle ß of approximately 20° between them. This can be achieved during production, for example, by a forming process such as bending the circuit board in the region of the carrier element 18. By deflecting the carrier element 18 by the angle ß, the carrier element can be brought into contact with or in the immediate vicinity of one of the battery cells 16 of the battery pack 10. Of course, a larger or smaller bending angle ß can also be selected depending on the design of the battery pack. Furthermore, it is also conceivable that the entire carrier element does not extend in one plane at an angle to the rest of the circuit board, but that the carrier element is, for example, bulged out in some areas or is otherwise deformed in order to form a projection for a temperature sensor to be accommodated.

[0037] The carrier element 18 is in the embodiments of the Fig. 1 to 6 on its side facing the battery cells 16 with a temperature sensor 22 (shown in Fig. 2, Fig. 4 and Fig. 5) that is in direct contact with at least one of the battery cells 16 or, as shown in the Fig. 2, Fig. 4 and Fig. 5, can be brought into close proximity to at least one battery cell 16.

[0038] According to the first embodiment of the Fig. 1 and Fig. 2, a recess 24 with insertion bevels 26 is provided on the cell carrier 14, which enables contact or direct proximity to the central battery cell. In an alternative design of the cell holder 14, such a recess 24 can be omitted. For example, a design variant of the cell holder as described in EP 1 927 152 B1 can be provided, which, for example, is particularly well suited to the solution according to Fig. 3 to 5 can be combined.

[0039] In contrast to the representation of the Fig. 1 and Fig. 2 is in the Fig. 3 to 5, a hold-down device 28 is provided on the housing shell 30, which presses the carrier element 18 in the direction of the at least one battery cell 16. As in the Fig. As can be seen in Figure 4, the hold-down device 28 protrudes from a housing shell 30 in the direction of the battery cells 16, which is arranged on a side of the circuit board 12 facing away from the battery cells 16 (upper housing shell). The hold-down device can serve to deflect or secure an already deflected support element. Accordingly, the hold-down device can be designed as a single holding structure or as part of a holding structure that, for example, can hold further elements, as in the Fig. 1, Fig. 2 and Fig. 6 shown.

[0040] The Fig. Finally, Figure 6 shows a further embodiment in which an additional snap hook 32 is provided on the cell carrier 14, which engages over the carrier element 18 in the assembled state. The cell holder 14 in this embodiment is like the cell holder of the Fig. 1 and Fig.2 and also has insertion bevels 26 and a recess 24. In addition, increased elasticity of the carrier element in the transition area to the circuit board 12 is provided by the fact that the carrier element 18 is provided with an additional milled recess 34 in the transition area, which results in a reduced material thickness of the circuit board in this area and thus greater elasticity.

[0041] Depending on the initial thickness of the printed circuit board 12, however, such a milled recess 34 may be omitted. For example, it is conceivable to use a printed circuit board with a total thickness of approximately 1 mm, which, according to practical tests, has sufficient elasticity to move the carrier section or carrier element 18 into the desired position.

[0042] What all the battery packs shown have in common is that the temperature sensor 22 is attached directly to the circuit board 12, so that complex connecting elements for assembly, such as additional stranded wires, connecting wires or the like, can be dispensed with.

Claims

[1] Battery pack (10) for an electrical device with at least one printed circuit board (12), at least one battery cell (16) and at least one temperature sensor (22) for measuring the temperature of at least one battery cell (16), wherein the temperature sensor (22) is attached directly to the printed circuit board (12), and wherein a section of the printed circuit board (12) forms a carrier element (18) to which the temperature sensor (22) is attached, characterized by that the carrier element is partially separated from the rest of the circuit board by a groove-shaped recess. [2] Battery pack (10) according to claim 1, characterized by that the carrier element (18) is formed in one piece with the circuit board (12). [3] Battery pack according to one of the preceding claims, characterized bythat, for example, a section of the circuit board is deformed by a forming process or elastically, for example bent, so that the carrier element or at least the temperature sensor extends, at least in the assembled state, in a plane which is not parallel to the rest of the circuit board. [4] Battery pack according to one of the preceding claims, characterized by that the at least one temperature sensor (22) is arranged on a side of the circuit board (12) facing the at least one battery cell (16) or on a side of the circuit board (12) facing away from this. [5] Battery pack (10) according to one of the preceding claims, characterized by that the circuit board (12) is elastically designed at least in the region of the carrier element (18) in order to be able to elastically prestress the temperature sensor (22) in the direction of at least one battery cell (16). [6] Battery pack (10) according to one of the preceding claims, characterized byin that the battery pack further comprises a cell holder (14) and / or a housing (30), wherein a holding structure is provided on the cell holder (14) or the housing (30) which, in the mounted state, holds the temperature sensor (18) attached to the circuit board (12) in contact with or at least in the immediate vicinity of at least one battery cell (16). [7] Battery pack (10) according to claim 6, characterized by that the holding structure comprises a snap hook (32) which, in the assembled state, engages behind the support element (18) in sections and holds it in the desired position. [8] Battery pack (10) according to claim 6 or 7, characterized by that the holding structure comprises a hold-down device (28) which, in the assembled state, presses the carrier element (18) in the direction of at least one battery cell (16) and holds it in the desired position. [9] Electric hand tool with a battery pack (10) according to one of the preceding claims, for supplying an electric motor with electrical energy, wherein the battery pack (10) is detachably connectable, in particular coupleable, to the electric hand tool.

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