Energy storage unit for an electrical consumer

Abstract

The invention relates to an energy storage unit (16) for an electrical consumer (10) comprising at least one first energy storage cell (20), at least one first temperature sensor (82) for detecting a temperature (T) of the at least one first energy storage cell (20), and a circuit board (58) for receiving the at least one first temperature sensor (82). According to the invention, the at least one first temperature sensor (82) and the circuit board (58) are surrounded, in particular entirely, by a thermally conductive potting compound (60), wherein the thermally conductive potting compound (60) is designed in such a way that it is in contact with the at least one first energy storage cell (20), in particular in place of the at least one first temperature sensor (82).

Description

[0001] Energy storage unit for an electrical consumer

[0002] Description

[0003] The invention relates to an energy storage unit for an electrical consumer according to the preamble of independent claim 1. The energy storage unit comprises at least one first energy storage cell, at least one first temperature sensor for detecting a temperature of the at least one first energy storage cell and a circuit board for receiving the at least one first temperature sensor.

[0004] State of the art

[0005] A large number of electrical consumers are operated with permanently integrated energy storage units (also known as rechargeable batteries or battery packs) or energy storage units that can be replaced by the operator without tools (hereinafter referred to as interchangeable battery packs). These units are discharged by the electrical consumer and recharged using a charger. Typically, such energy storage units consist of a plurality of energy storage cells connected in series and / or parallel to achieve a required battery voltage or capacity. If the energy storage cells are designed as lithium-ion (Li-ion) cells, for example, a high power and energy density can be achieved with particular advantage. On the other hand, such cells also require compliance with strict specifications regarding maximum charging and discharging current, voltage, and temperature to avoid electrical faults.If, for example, the detected temperature is outside specified limits, the discharging or charging process of the energy storage unit is interrupted or at least restricted.

[0006] In modern, battery-operated electrical devices, the cell voltage of the parallel-connected energy storage cells of a so-called cell cluster of the energy storage unit is evaluated, for example, by a monitoring unit. The term "cell voltage" therefore refers not only to the voltage of a single energy storage cell, but also to the voltage of a cell cluster consisting of energy storage cells connected in parallel. Such so-called single-cell monitoring (SCM) is known, for example, from WO 20043386 A1, which also prevents dangerous operation of a removable battery pack in the event of a fault through redundant monitoring.

[0007] The object of the invention is to achieve a particularly robust and reliable temperature detection in an energy storage unit for safe operation in conjunction with the simplest possible production of the energy storage unit.

[0008] Advantages of the invention

[0009] To achieve the above object, it is provided that the at least one first temperature sensor and the circuit board are surrounded, in particular completely, by a thermally conductive potting compound, wherein the potting compound is designed such that it comes into thermal contact with the at least one first energy storage cell, in particular at the location of the at least one first temperature sensor. This particularly advantageously enables simple and cost-effective production of the energy storage unit in conjunction with reliable and safe temperature monitoring.

[0010] The invention further relates to an electrical consumer with an energy storage unit according to the invention and to a system comprising an electrical consumer designed as a hand-held power tool and at least one energy storage unit designed as a removable battery pack. However, in the context of the invention, an electrical consumer should basically be understood as all devices with an electrical load that can be supplied by means of an energy storage unit, such as a removable battery pack or a permanently integrated battery pack. The electrical load can be a predominantly inductive load in the form of an electric motor drive. Predominantly resistive or capacitive loads are also conceivable. Electrically commutated electric motors (so-called EC orBLDC motors) are suitable, the individual phases of which are controlled via at least one power transistor using pulse width modulation to control or regulate their speed and / or torque. In this context, the invention is applicable to battery-operated machine tools for machining workpieces using an electrically driven tool. The electrical processing device can be designed both as a handheld power tool and as a stationary machine tool. Typical machine tools in this context are handheld or pillar drills, screwdrivers, impact drills, planers, angle grinders, orbital sanders, cell polishing machines, or the like. Other electrical consumers include garden and construction equipment such as lawn mowers, grass trimmers, pruning saws, power cutters and trenchers, blowers, robot breakers and excavators, or the like, as well as measuring devices such as laser rangefinders, wall scanners, etc.Furthermore, the invention is applicable to household appliances, such as vacuum cleaners, mixers, etc., and electrically powered road and rail vehicles, such as e-bikes, e-scooters, pedelecs, electric and hybrid vehicles, etc., as well as aircraft and ships with an energy storage unit according to the invention.

[0011] The voltage class of the energy storage unit results from the connection (parallel or series) of the individual energy storage cells integrated in the energy storage unit and is generally an integer multiple (>= 1) of the voltage of the individual energy storage cells. An energy storage cell is typically designed as a galvanic cell with a structure in which one cell pole is located at one end and another cell pole at an opposite end. In particular, the energy storage cell has a positive cell pole at one end and a negative cell pole at an opposite end. The energy storage cells are preferably designed as lithium-based battery cells, e.g. Li-ion, Li-cell polymer, Li-metal or the like. However, the invention is also applicable to energy storage units with Ni-Cd, Ni-Mh cells or other suitable cell types.For common Li-ion energy storage cells with a cell voltage of 3.6 V, voltage classes of 3.6 V, 7.2 V, 10.8 V, 14.4 V, 18 V, 36 V, etc. are obtained, for example. An energy storage cell is preferably designed as an at least substantially cylindrical round cell, with the cell poles arranged at the ends of the cylinder. However, the invention is not dependent on the type and design of the energy storage cells used, but can be applied to any energy storage units and cells, e.g., in addition to round cells, also prismatic cells, pouch cells or the like. The DC voltage values ​​are primarily based on the typical cell voltages of the energy storage cells used. For example, for pouch cells and / or cells with a different electrochemical composition, voltage values ​​are possible that differ from those of energy storage units equipped with Li-ion cells.

[0012] If the energy storage unit is designed as a removable battery pack, it can be detachably connected in a force-locking and / or form-locking manner via an electromechanical interface of the removable battery pack to a correspondingly complementary electromechanical interface of the electrical consumer or charger. A "detachable connection" is to be understood in particular as a connection that can be released and established without tools - i.e., by hand. The design of the electromechanical interfaces and their receptacles for the force-locking and / or form-locking detachable connection are not the subject of this invention. A person skilled in the art will select a suitable embodiment for the electromechanical interface depending on the power or voltage class of an electrical consumer and / or removable battery pack, so this will not be discussed in further detail here. The embodiments shown in the drawings are therefore to be understood only as examples.In particular, interfaces with more electrical contacts than those shown can be used.

[0013] In a further development of the invention, it is provided that the at least one first temperature sensor is arranged on a circuit board layer of the circuit board, and the potting compound has a recess on a side of the circuit board opposite the circuit board layer in the region of the at least one first temperature sensor, in particular for thermally insulating the circuit board or the at least one first temperature sensor from a housing of the energy storage unit or the electrical load. In a particularly advantageous manner, the heat capacity in the immediate vicinity of the temperature sensor can thereby be reduced in order to avoid or at least reduce temperature influences of other components and / or the housing of the energy storage unit or the electrical load on the temperature sensor.

[0014] The recess can be designed such that a cavity is formed between the potting compound and the housing, which defines a distance between the potting compound and the housing, at least in the region of the at least one first temperature sensor. This further reduces or prevents any impairment of the temperature measurement caused by temperature influences acting on the housing.

[0015] Additionally, a further temperature sensor can be arranged on the circuit board, which is spaced apart from the first temperature sensor in such a way that it detects the temperature of another energy storage cell. The further temperature sensor is surrounded by the encapsulating compound in such a way that it comes into thermal contact with the other energy storage cell, particularly at the location of the further temperature sensor. Thus, multiple energy storage cells can be monitored in the sense of thermal single-cell monitoring and, if necessary, deactivated separately via corresponding switching elements on the circuit board if specified temperature limits are exceeded or undershot.

[0016] To optimize thermal conductivity between the temperature sensor and the energy storage cell, the thermal contact surfaces of the encapsulating compound are adapted to the outer contour of the energy storage cell. For example, if the energy storage cells are cylindrical, round cells, optimized conductivity is achieved if the thermal contact surfaces of the encapsulating compound have a complementary, particularly concave, shape to create the largest possible surface area that transmits the temperature of the energy storage cells to the temperature sensors. Furthermore, such a positive fit allows for simplified assembly of the circuit board, since the appropriately preformed encapsulating compound ensures reproducible positioning on the energy storage cells.

[0017] An alternative or supplementary option for reducing or avoiding the impairment of temperature measurement due to temperature influences acting on the housing is possible in that the potting compound has at least one protruding contact point for the housing of the energy storage unit or the electrical load on a side facing away from the at least one first energy storage cell, forming an air gap between the housing and the potting compound. The air gap can also be formed by two contact points of the potting compound, with the temperature sensors arranged substantially centrally between the two contact points.

[0018] In a further development of the invention, the potting compound is designed as an elastic thermoplastic. Such a thermoplastic can be produced, for example, using so-called low-pressure molding. The circuit board, including its electrical connection points, is placed in a negative mold, which is then filled with a hot, viscous polymer. After the polymer has cooled, a robust and partially elastic shell is created, which ensures very good protection against corrosion caused by moisture, fingerprints, or the like. The elasticity of the thermoplastic allows tolerances between the circuit board or the temperature sensor and the energy storage cell to be compensated, which improves thermal conductivity.

[0019] In order to keep the design of the energy storage unit as compact as possible, the circuit board surrounded by the potting compound is arranged on two adjacent energy storage cells in such a way that it does not protrude beyond an envelope formed by the two energy storage cells in a cross-section.

[0020] Typically, the electrical cell poles of at least two energy storage cells of the energy storage unit are electrically connected to one another in a series or parallel circuit via at least one cell connector. The electrical connection of the cell connectors to the electrical cell poles is achieved by means of a material-to-material connection, for example by soldering, cold welding, or the like. The cell connectors are designed as flat stamped sheets or tabs, which in turn are electrically connected to a printed circuit board (PCB) of the energy storage unit for monitoring the energy storage cells via electrical connection points on the circuit board. The electrical connection between the connection points of the circuit board and the cell connectors is also made by means of a material-to-material connection using electrical cables, ribbon cables, bonding wires, lead frames, or the like. Flexible printed circuit boards (FPCs) are also sometimes used.In an alternative embodiment of the invention, the object can therefore be seen in achieving a particularly robust electrical connection of individual energy storage cells of an energy storage unit to the circuit board in conjunction with the simplest possible production of the energy storage unit.

[0021] To solve this problem, the circuit board, including the electrical connection points, is completely encased in a potting compound. This provides effective protection for the electrical connections between the circuit board and the cell connector against contamination and shunts, while also avoiding time-consuming and error-prone soldering during assembly of the energy storage unit.

[0022] In a further development of the invention, the potting compound is made of a low-pressure molding thermoplastic. In low-pressure molding, the circuit board, including its electrical connection points, is placed in a negative mold, which is then filled with a hot, viscous polymer. After the polymer cools, a robust and partially elastic shell is created, providing excellent protection against corrosion caused by moisture, fingerprints, or the like. Alternatively, it is also conceivable for the potting compound to be made of a silicone compound, with corresponding advantages.

[0023] In addition, at least one of the cell connectors has an electrical tap for single-cell monitoring (SCM) of the energy storage cells. Since no additional material connection for the SCM tap is required during assembly of the energy storage unit, it is at least partially protected against contamination and / or corrosion, significantly reducing the risk of unwanted discharge of the energy storage unit or individual energy storage cells.

[0024] Furthermore, it is provided that at least one of the cell connectors has a tolerance compensation for adapting to the length of the energy storage cells. Since the electrical connection of the cell connectors to the circuit board is already established during assembly and the individual components each have fixed lengths, the tolerance compensation makes it possible to compensate for any length tolerances of the energy storage cells, the circuit board, and / or their connection points. The tolerance compensation of the cell connector can be designed as a U-shaped, zigzag, or wave-shaped fold parallel to a longitudinal axis of the respective energy storage cell.

[0025] The invention also relates to a method for producing an energy storage unit for an electrical consumer, comprising a plurality of energy storage cells, each energy storage cell having two electrical cell poles and the electrical cell poles of at least two energy storage cells being electrically connected to one another in a series or parallel circuit via at least one cell connector, and comprising a printed circuit board having at least one electrical connection point for electrically connecting the at least one cell connector. With the advantages mentioned above, the at least one cell connector is first electrically connected, in particular by a material bond, to the electrical connection point in one method step.In subsequent process steps, the circuit board, including the at least one electrical connection point, is then potted, in particular completely, with a potting compound and arranged parallel to a longitudinal axis of the energy storage cells in order to firmly connect the at least one cell connector to the electrical cell poles of at least two energy storage cells. In the context of the invention, a firmly connected connection is understood to mean, in particular, an electrical connection created by soldering, cold welding, or the like.

[0026] In a method step of the method according to the invention, it is additionally provided that the circuit board is electrically connected to at least one further circuit board by means of a flexible line, in particular a multi-core ribbon cable, before being potted with the potting compound. The further circuit board can, for example, have a plurality of electrical contacts of the electromechanical interface of the energy storage unit designed as a removable battery pack for contacting the electrical consumer or a charger. After potting with the potting compound, the circuit board and the at least one further circuit board are then arranged essentially at right angles to one another around the energy storage rows in a method step. Instead of a flexible line, the further circuit board can also be designed as a flexible circuit board and be electrically connected directly to the circuit board, in particular by a material bond.

[0027] In a further, alternative embodiment of the invention, the object can be seen in achieving a particularly simple and accurate temperature detection of an energy storage unit, in particular of an energy storage cell of the energy storage unit, for a safe operation of the energy storage unit.

[0028] To achieve this objective, the at least one first temperature sensor is arranged for thermal coupling with the at least one energy storage cell on the side edge or on the circuit board layer directly adjacent to the side edge. Since the accuracy of temperature detection depends on the thermal conductivity between the energy storage cell and the temperature sensor, the invention particularly advantageously enables the heat generated during the charging or discharging process to be transferred from the energy storage cell to the temperature sensor in a targeted manner and with as little loss as possible. At the same time, the proposed solution is very cost-effective, especially since no separate mounting devices or adhesive bonds are required.

[0029] In a further embodiment, it is provided that the circuit board spans a circuit board plane, wherein a longitudinal axis of the at least one energy storage cell, in particular of a plurality of parallel energy storage cells, is aligned perpendicular to the circuit board plane. Furthermore, the side edge can be adapted to an outer contour of the at least one energy storage cell, at least in the region of the at least one temperature sensor. Additionally or alternatively, the side edge has at least one contact point with the at least one energy storage cell. In this way, optimal thermal contact of the temperature sensor positioned on the side edge can be achieved depending on the outer contour of the at least one energy storage cell.

[0030] Furthermore, the thermal contact between the at least one temperature sensor and the at least one energy storage cell can be improved in that the circuit board has at least one recess in the vicinity of the at least one first temperature sensor, which recess causes a spring force of the side edge relative to the at least one energy storage cell in such a way that the at least one energy storage cell deforms the side edge and / or the recess in the assembled state of the circuit board due to a compressive force. In the event of deformation of the side edge, this is preferably designed to be compressed in the plane of the circuit board. Due to the compressive force and the spring force counteracting this compressive force, the at least one temperature sensor is always held optimally on the energy storage cell. Furthermore, the recess can cause thermal decoupling of the at least one temperature sensor from the rest of the circuit board.

[0031] Particularly advantageously, the at least one first temperature sensor is designed as an SMD component, which is arranged on the at least one circuit board layer or directly in a recess in the side edge. SMD components are very compact and therefore allow for particularly space-saving and cost-effective assembly in series production.

[0032] The thermal coupling can be further improved by the side edge having a thermally conductive coating at least in the immediate vicinity of the at least one first temperature sensor.

[0033] A supplementary embodiment of the invention provides for a further temperature sensor to be arranged on the side edge or a further side edge of the circuit board, wherein the further temperature sensor is spaced from the first temperature sensor such that it detects the temperature of a further energy storage cell, in particular largely independently of the first energy storage cell. Thus, multiple energy storage cells can be monitored in the sense of thermal single-cell monitoring and, if necessary, deactivated separately via corresponding switching elements on the circuit board if predetermined temperature limits are exceeded or undershot.

[0034] In order to reduce or avoid falsification of the temperature detection, it can also be provided that the circuit board has at least one further recess for thermal decoupling in the vicinity of the at least one first temperature sensor and / or the further temperature sensor.

[0035] Examples of implementation

[0036] drawing

[0037] The invention is explained below by way of example with reference to Figures 1 to 13, wherein the same reference numerals in the figures indicate the same components with the same mode of operation.

[0038] It shows

[0039] Fig. 1: an electrical consumer designed as a hammer drill according to the prior art in a perspective view,

[0040] Fig. 2: a perspective view of an electrical consumer designed as a multi-tool according to the prior art,

[0041] Fig. 3: a perspective view of an energy storage unit designed as a 12V interchangeable battery pack according to the prior art,

[0042] Fig. 4: a perspective view of an energy storage unit designed as an 18V interchangeable battery pack according to the prior art,

[0043] Fig. 5: a first embodiment of the inner part of the energy storage unit according to the invention in a perspective view before (Figure 5a) and after its assembly (Figure 5b), Fig. 6: a detailed view of the inner part of the energy storage unit according to the invention

[0044] Energy storage unit according to Figure 5,

[0045] Fig. 7: a cell connector of the energy storage unit according to the invention according to Figures 5 and 6 in a perspective view,

[0046] Fig. 8: a section through the energy storage unit according to the invention at approximately half the length of the energy storage unit,

[0047] Fig. 9: a detailed view of the inner part of the inventive

[0048] Energy storage unit according to Figures 5 to 8 in a perspective view,

[0049] Fig. 10: another embodiment of the inventive

[0050] Energy storage unit in a frontal view,

[0051] Fig. 11: Detailed views of various alternative embodiments (Figures 11a to 11d) of a printed circuit board of the energy storage unit according to the invention according to Figure 10,

[0052] Fig. 12: a detailed view of another embodiment of the

[0053] Printed circuit board of the energy storage unit according to the invention according to Figure 10 and

[0054] Fig. 13: Detailed views of various alternative embodiments (Figures 13a to 13d) of a side edge of the circuit board of the energy storage unit according to the invention according to Figure 10.

[0055] Description of the embodiments

[0056] Figure 1 shows an example of an electrical load 10 designed as a hammer drill 12 with a housing 14. In addition to a percussion mechanism (not shown in detail), which is driven by an electric motor (also not shown in detail), in particular a brushless direct current (DC) motor (electrically commutated - EC or brushless direct current - BLDC), an energy storage unit 16 for supplying energy to the electric motor and to electronics controlling it (not shown) is arranged in the housing 14 of the hammer drill 12. The energy storage unit 16 is designed as a permanently integrated battery pack 18 that cannot be replaced by the operator. The battery pack 16 can comprise a single energy storage cell 20 or a plurality of energy storage cells 20 (see Figures 5, 8 and 10). As already mentioned at the beginning, the battery voltage Ußatt of the energy storage unit 18 is generally an integer multiple (>= 1) of the individual orCell voltages Uceii of the energy storage cells 20 depend on their connection (parallel or series). The energy storage cells 20 are preferably designed as lithium-based rechargeable cells, e.g., Li-ion, Li-Po, Li-metal, or the like. However, the invention is also applicable to energy storage units 18 with Ni-Cd, Ni-MH cells, or other suitable cell types.

[0057] The speed and / or torque of the electric motor, designed as an EC motor, can be controlled or regulated, for example, by means of the electronics and an inverter controlled by the electronics (e.g., an H-bridge consisting of semiconductor switches, a Bö bridge, or the like) via pulse width modulation (PWM) depending on a main switch 22. Since the functionality of a PWM control is known to those skilled in the art, it will not be discussed in further detail here. Furthermore, other control or regulation methods for corresponding electric motors are also known without limiting the invention.

[0058] Figure 2 shows a further exemplary embodiment of an electrical consumer 10 in the form of an electric motor-driven multi-tool 24. Instead of a single main switch 22, this is divided into a pure on / off switch arranged on the top of the housing 14 and a speed controller arranged on the side of the housing 14. A further, significant difference from the hammer drill 12 shown in Figure 1 lies in the interchangeability of the energy storage unit 16, designed as a replaceable battery pack 26. For the connection to the multi-tool 24 that can be released without tools - i.e. by hand - the replaceable battery pack 26 has an electromechanical interface 28 (cf. the following explanations according to Figures 3 and 4), which can be plugged into an electromechanical interface 30 of the multi-tool 24 designed as a plug-in receptacle. When the replaceable battery pack 26 is fully plugged in, it can power the multi-tool 26 orsupply its electric motor and electronics with the required battery voltage Ußatt. A plugged-in interchangeable battery pack 26 is understood in particular to mean an interchangeable battery pack 26 whose electromechanical interface 28, when connected to the electrical consumer 10, is connected to the correspondingly complementary electromechanical interface 30 of the electrical consumer 10.

[0059] It should be noted again that the invention is also applicable to electrical consumers that have purely resistive and / or capacitive electrical loads, so that the power tools shown here are to be understood merely as examples and are primarily intended to illustrate the different types of energy storage units 20 and their application.

[0060] Figures 3 and 4 show perspective views of two different interchangeable battery packs 26. In addition to their characteristic shape, the interchangeable battery packs 26 differ particularly in their battery voltage U, capacity, and their electromechanical interfaces 28.

[0061] Figure 3 shows a removable battery pack 26 with a battery voltage Ußatt of 10.8 V (nominally 12 V). The removable battery pack 26 has a housing 14 in which three cylindrical energy storage cells 20 (see Figures 5 and 8), each with a cell voltage Uceii of 3.6 V, are arranged and electrically connected in series. The removable battery pack 26 is designed such that it can be removably inserted into the electrical consumer 10 shown in Figure 2, which is designed as a multi-tool 24, without the need for tools.

[0062] The removable battery pack 26 has an electrical contact part 32 of the electromechanical interface 28 at one end, which comprises two electrical contacts 34, which are designed as power supply contacts 36, and three further electrical contacts 34, which are designed as signal or data contacts 38. The power supply contacts 36 can be used to supply the electrical load 10 or the multi-tool 24 with power. On the other hand, this also makes it possible to charge the removable battery pack 26 using a charger (not shown). Information about various operating parameters of the removable battery pack 26, such as the battery voltage UBatt, the cell voltages Uceii, a temperature T measured in the removable battery pack 26, a charging or discharging current I, a coding, or the like, can be transmitted to the electrical load 10 or the charger via the signal or data contacts 38 for evaluation there.Based on these operating parameters, the electronics of the electrical consumer 10 or the charger can control or regulate the discharging or charging process.

[0063] On an end of the removable battery pack 26 opposite the end with the electrical contact part 32 of the electromechanical interface 28, a mechanical contact part 40 is arranged for the tool-free mechanical connection of the removable battery pack 26 to the electrical consumer 10. The mechanical contact part 40 comprises two spring-loaded locking lugs 42, which can be connected to the housing 14 of the electrical consumer 10 in a force-locking and form-locking manner. As a rule, no corresponding locking is necessary in the charger, so the locking lugs 42 are not used there. However, it is conceivable that the removable battery pack 26 could also be locked in the charger during the charging process.

[0064] Figure 4 shows a removable battery pack 26 with a battery voltage UBatt of 18 V. Ten cylindrical energy storage cells 20 are arranged in two layers in the housing 14 of the removable battery pack 26. Two energy storage cells 20 are connected in parallel to form a cell cluster. The five cell clusters are then connected in series, so that with a cell voltage Uceii of 3.6 V each, the resulting battery voltage Ußatt is 18 V. A charge level indicator 44 is arranged on the outer surface of the housing 14 of the removable battery pack 26, via which the charge level can be displayed. The electromechanical interface 28 of the removable battery pack 26 has two guide rails 46, which, when inserted, are guided into corresponding guide grooves of the electromechanical interface 30 of the electrical consumer 10 or the charger.In addition, a locking element 48 is provided, which is designed to lock the removable battery pack 26 to the electrical consumer 10. The locking element 48 is designed as a pivoting and spring-mounted latching means that automatically engages at the end of the insertion process. The inserted removable battery pack 26 can be unlocked by actuating a mechanical actuating element (not shown) arranged on a side of the removable battery pack 26 opposite the charge level indicator 44. The electrical contact part 32 of the electromechanical interface 28 is arranged between the two guide rails 46 and has a plurality of electrical contacts 34 for energy and data transmission, corresponding to the removable battery pack 26 shown in Figure 3. In particular, the signal or data contact 38 is designed as a coil that inductively transmits the operating parameters to the electrical consumer 10.An electrical contact 34 should therefore also be understood as a contact that enables contactless energy and / or data transmission.

[0065] Figure 5a shows the interior of the removable battery pack 26 shown in Figure 3 prior to its assembly. The removable battery pack 26 comprises three Li-ion energy storage cells 20, which are arranged such that their cross-section has a substantially triangular outer contour (see also Figure 8). Each energy storage cell 20, in turn, has a positive and a negative cell pole 50 on its end faces. Figure 5b shows the removable battery pack 26 after the interior has been assembled. In contrast to Figure 3, the electrical contact part 32 of the electromechanical interface 28 has only two instead of three signal or data contacts 38. The three energy storage cells 20 are connected in series by means of two cell connectors 52, so that with a cell voltage Uceii of 3.6 V each, a battery voltage Ußatt of 10.8 V results.

[0066] Each cell connector 52 is formed as a flat stamped sheet metal which, as shown in Figure 6, is electrically connected at a first end 54 to an electrical connection point 56 of a printed circuit board 58 by a material fit, for example by soldering. Subsequently, the printed circuit board 58, including its electrical connection points 56 and the ends 54 of the cell connectors 52, is encapsulated, in particular completely, with a potting compound 60. The potting compound 60 can, for example, be made of a low-pressure molding thermoplastic. During low-pressure molding, the printed circuit board 58, including its electrical connection points 56, is placed in a negative mold, which is then filled with a hot, viscous polymer. After the polymer has cooled, a robust and partially elastic shell is created, which ensures very good protection against corrosion caused by moisture, fingerprints, or the like.Alternatively, it is also conceivable for the potting compound 60 to be formed from a silicone compound. Figure 6 shows the circuit board 58, including its electrical connection points 56 and the ends 54 of the cell connectors 52, after being potted with the potting compound 60 in a side sectional view, with the potting compound 60 shown in dashed lines to better illustrate its internal components.

[0067] In a subsequent step, the encapsulated circuit board 58 is arranged parallel to a longitudinal axis 62 of the energy storage cells 20, as shown in Figures 5a and 5b. Finally, at the end of the assembly of the inner part, the cell connectors 52, formed as flat stamped sheets or tabs, are integrally connected to the cell terminals 50 of the energy storage cells 20 by a cold welding process via corresponding contact points 64 (see also Figure 7).

[0068] If necessary, the circuit board 58 can be electrically connected to at least one further circuit board 70 by means of a flexible cable 66, in particular a multi-core ribbon cable 68, before being potted with the potting compound 60. The further circuit board 70 is connected in particular to two further stamped sheets 72, which serve to electrically connect the positive cell pole 50 of the first energy storage cell 20 and the negative cell pole 50 of the last energy storage cell 20 of the series circuit to the positive and negative power supply contacts 36 of the electromechanical interface 28, respectively. The two power supply contacts 36 are soldered directly onto the further circuit board 70 for this purpose, but can also be electrically connected with corresponding cables. The same applies to the further stamped sheets 72.The circuit board 58 and the at least one further circuit board 70 are finally arranged around the energy storage cells 20, essentially at right angles to one another after being potted with the potting compound 60. At least one of the cell connectors 52 has an SCM tap 74 for individual cell monitoring, which is integrally connected to the cell connector 52 and is preferably arranged between the end 54 for electrical contact with the circuit board 58 and the contact points 64 for electrical contact with the cell poles 50 of the energy storage cells 20. The SCM tap 74 is integrally connected, for example by soldering, to a cable (not shown), which in turn is connected to an SCM pre-stage (not shown) of a corresponding electronics system, which is arranged either in the removable battery pack 26 or in the electrical load 10, if this has a permanently integrated battery pack 18 according to Figure 1.To measure the individual cell voltages Uceii, the SCM pre-stage switches sequentially, for example via integrated transistors, between the individual SCM taps 74 of the cell connectors 52 in such a way that each is connected to a positive and a negative cell pole 50 of the energy storage cell 20 to be measured. The term "energy storage cell" should also include a cell cluster, since this only influences the capacity of the interchangeable battery pack 10, but is equivalent for measuring the cell voltages Uceii.

[0069] The electronics of the removable battery pack 26 or the electrical consumer 10 can comprise an integrated circuit in the form of a microprocessor, ASIC, DSP, or the like for controlling or regulating the charging or discharging process. It is also conceivable for the control or regulation to be carried out by means of several microprocessors or at least partially by means of discrete components with corresponding transistor logic. Furthermore, the electronics can comprise a memory for storing the operating parameters. Since such electronics are known to those skilled in the art, they will not be discussed further here.

[0070] Figure 7 shows a detailed view of one of the cell connectors 52. This has at least one tolerance compensation 76 for adapting to a length L of the energy storage cells 20 (see Figures 5a and 5b). The tolerance compensation 76 of the cell connector 52 is designed as a U-shaped fold 78 parallel to the longitudinal axis 62 of the respective energy storage cell 20, wherein the orientation of the fold 78 can be configured differently depending on the spatial conditions and the material thickness of the stamped sheet. Instead of a U-shaped fold, a zigzag or wave-shaped fold is also conceivable. Since the electrical connection of the cell connectors 52 to the circuit board 58 is already established during its assembly and the individual components each have fixed lengths, the tolerance compensation 76 makes it possible to compensate for any length tolerances of the energy storage cells 20, the circuit board 58 and / or their connection points 54, 56.

[0071] Figure 8 shows a cross-section of the removable battery pack 26 through the three energy storage cells 20 arranged in a triangle, surrounded by the housing 14 of the removable battery pack 26. The section shown is located approximately at the level of half the length L of the energy storage cells 20 (see Figure 5). To keep the design of the removable battery pack 26 as compact as possible, the circuit board 58 surrounded by the potting compound 60 is arranged on two adjacent energy storage cells 20 in such a way that it does not protrude beyond an envelope curve 80 formed by the energy storage cells 20 in cross-section.

[0072] By means of a first temperature sensor 82, which is preferably designed as an NTC and arranged in SMD (Surface Mounted Device) design on a circuit board layer 84 of the circuit board 58, the temperature T of at least one of the energy storage cells 20 can be measured and evaluated by the electronics of the removable battery pack 26 or the electrical load 10 or the charger. For this purpose, the first temperature sensor 82 is in the closest possible thermal contact with the energy storage cell 20. In addition, it is electrically connected to one of the signal or data contacts 38 of the electromechanical interface 28 for transmitting the measured temperature T. In the case of a battery pack 18 permanently integrated into the electrical load 10, the first temperature sensor 82 can also be connected directly to the electronics of the electrical load 10. The circuit board 58 and the first temperature sensor 82 are surrounded, in particular completely, by the potting compound 60.For particularly good thermal connection of the temperature sensor 82 to the energy storage cell 20, the potting compound 60 is designed to be thermally conductive and comes into thermal contact with the energy storage cell 20, in particular at the location of the temperature sensor 82.

[0073] In addition to the first temperature sensor 82, a further temperature sensor 86 is arranged on the circuit board 58, which is spaced from the first temperature sensor 82 such that it detects the temperature T of a further energy storage cell 20. The further temperature sensor 86 is surrounded by the temperature-conductive potting compound 60, corresponding to the first temperature sensor 82, such that it comes into the best possible thermal contact with the further energy storage cell 20, in particular at the location of the further temperature sensor 86. Thus, both energy storage cells 30 can be monitored in the sense of thermal single-cell monitoring and, if necessary, deactivated separately via corresponding switching elements on the circuit board 58, for example by the SCM preamplifier, if predetermined temperature limits are exceeded or undershot.

[0074] To optimize the thermal conductivity between the temperature sensors 82, 86 and the energy storage cells 20, the thermal contact surfaces 88 of the thermally conductive potting compound 60 are adapted to an outer contour 90 of the energy storage cells 20. In the present exemplary embodiment, the energy storage cells 20 are designed as cylindrical, round cells. Thus, optimized thermal conductivity results when the thermal contact surfaces 88 of the thermally conductive potting compound 60 have a complementary, concave shape in order to form the largest possible surface area that transmits the temperature T of the energy storage cells 20 to the temperature sensors 82, 86. Furthermore, such a positive fit allows for simplified assembly of the potted circuit board 58, since the correspondingly preformed potting compound 60 ensures reproducible positioning on the energy storage cells 20.As already mentioned at the beginning, other forms of energy storage cells 20 are also conceivable. Accordingly, the thermal contact surfaces 88 of the thermally conductive encapsulant 60 should be designed to complement them.

[0075] According to Figure 9, on a side of the circuit board 58 opposite the circuit board layer 84, a recess 92 is provided in the potting compound 60 in the area of ​​the temperature sensors 82, 86. The recesses 92 serve, in particular, to achieve thermal insulation of the circuit board 58 or the temperature sensors 82, 86 from the housing 14 of the removable battery pack 26 or the electrical load 10. This allows the heat capacity in the immediate vicinity of the temperature sensors 82, 86 to be reduced in order to avoid or at least reduce temperature influences of other components and / or the housing 14 of the removable battery pack 26 or the electrical load 10 on the temperature sensors 82, 86. The recesses 92 are designed such that a cavity is formed between the potting compound 60 and the housing 14, which cavity defines a distance between the potting compound 60 and the housing 14 at least in the region of the two temperature sensors 82, 86.Thus, any impairment of the temperature measurement due to temperature influences acting on the housing 14 can be further reduced or avoided.

[0076] In order to further reduce or avoid any impairment of the temperature measurement due to temperature influences acting on the housing 14, the thermally conductive potting compound 60 also has two protruding contact points 94 for the housing 14 of the removable battery pack 14 or the electrical consumer 10 on the side facing away from the energy storage cells 20 or the temperature sensors 82, 86 to form an air gap between the housing 14 and the potting compound 60. Preferably, the two temperature sensors 82, 86 are arranged substantially centrally between the two contact points 94, i.e., approximately at the level of half the length L of the energy storage cells 20 (cf. Figure 5b).

[0077] Figures 10 to 13 show further embodiments for the thermal coupling of the temperature sensors 82, 86 to the energy storage cells 20 in order to achieve high accuracy of temperature detection through optimized thermal conductivity between the energy storage cells 20 and the temperature sensors 82, 86.

[0078] In Figure 10, the temperature sensor 82 for thermal coupling with the energy storage cell 20 is arranged on the circuit board layer 84 directly next to a side edge 96 of the circuit board 58. The circuit board 58 spans a circuit board plane 98 that is aligned perpendicular to the longitudinal axis 62 of the energy storage cell 20. Alternatively, it is also conceivable to arrange the temperature sensor 82 directly in a corresponding recess in the side edge 96. The thermal coupling can also be improved if the side edge 96 has a thermally conductive coating 100, at least in the immediate vicinity of the temperature sensor 82. Likewise, with reference to the previous exemplary embodiment according to Figures 5 to 9, it is conceivable for the circuit board to be enclosed in the region of the side edge 96, in particular completely, by the thermally conductive potting compound 60.Thus, the heat generated during the charging or discharging process can be transferred from the energy storage cell 20 to the temperature sensor 82 in a targeted and low-loss manner. At the same time, cost-effective assembly is achieved, as no separate mounting devices or adhesive bonds are required. The temperature sensor 82 is designed as an SMD component arranged on the circuit board layer 84 or directly in the recess (not shown) of the side edge 96. This allows for a very small design and good point-based temperature measurement, combined with simple series production.

[0079] The side edge 96 is adapted to the outer contour 90 of the energy storage cell 20 in the area of ​​the temperature sensor 82. In the present exemplary embodiment, the energy storage cell 20 is designed as a cylindrical, round cell. Thus, optimized thermal conductivity is achieved if the side edge 96 of the circuit board 58 has a complementary, concave shape. As already mentioned at the beginning, other shapes of energy storage cells 20 are also conceivable. Accordingly, the side edge 96 should then be designed to complement it.

[0080] Particularly good thermal contact between the temperature sensor 82 and the energy storage cell 20 can additionally be achieved by the circuit board 58 having at least one recess 102 in the vicinity of the temperature sensor 82. When the circuit board 58 is mounted, the energy storage cell 20 deforms the recess 102 through a corresponding compressive force such that a spring force of the side edge 96 is generated against the energy storage cell 20. Furthermore, it is conceivable that the side edge 96 itself is also deformed by being compressed by the energy storage cell 20 in the circuit board plane 98, particularly when the recess 102 is surrounded by two areas of the circuit board 58 (not shown). The compressive force and the spring force counteracting it ensure that the temperature sensor 82 is always held optimally against the energy storage cell 20.Furthermore, the recess 102 can thermally decouple the at least one temperature sensor 82 from the remaining circuit board 58. The effect of the spring force and, if applicable, also the thermal insulation can be further enhanced by using multiple recesses 102 in the circuit board 58. Figures 11a to 11d show four further variants for a different number, arrangement, and / or shape of recesses 102.

[0081] According to Figure 12, the printed circuit board 58 can also be configured such that the additional temperature sensor 86 is arranged on a further side edge 104 of the printed circuit board 58 to detect the temperature T of a further energy storage cell 20. The additional temperature sensor 86 is spaced from the first temperature sensor 82 such that it can detect the temperature T of the additional energy storage cell 20 largely independently of the first energy storage cell 20. Thus, several energy storage cells 20 can be monitored in the sense of thermal single cell monitoring and, if necessary, deactivated separately via corresponding switching elements on the printed circuit board 58 or by means of electronics of the electrical load 10 if predetermined temperature limit values ​​are exceeded or undershot.The thermal coupling can be improved analogously to the first side edge 96 if the further side edge 104 has the thermally conductive coating 100 at least in the immediate vicinity of the further temperature sensor 86. Particularly good thermal contact between the temperature sensors 82, 86 and the energy storage cells 20 can be additionally achieved by the circuit board 58 also having at least one recess 102 in the vicinity of the further temperature sensor 86, which operates in a manner similar to the recess 102 for the first temperature sensor 82.

[0082] Instead of side edges 96, 104 resting flat on the outer contour 90 of the energy storage cells 20 to be monitored (see Figure 13a), it is also conceivable with reference to Figures 13b and 13c for the side edges 96, 104 to have one or two contact points 106 with the respective energy storage cells 20. In this way, optimal thermal contact of the temperature sensors 82, 86 positioned on the side edges 96, 104 can be achieved depending on the radius of the outer contours 90 of the energy storage cells 20. While a single contact point 106 according to Figure 13b is particularly advantageous for small radii of the energy storage cells 20, energy storage cells 20 with larger radii according to Figure 13b can be better thermally connected via two contact points 106. Another possibility for thermal connection is shown in Figure 13d, in which the side edge 96 or 104 is V-shaped and thus suitable for different radii orOuter contours 90 of the energy storage cells 20 always have two defined contact points 106.

[0083] Finally, it should be noted that the illustrated embodiments are neither limited to Figures 1 to 13 nor to the shape, number, and size of the energy storage cells 20 shown therein. The number of temperature sensors may also vary accordingly. Furthermore, in addition to NTCs, PTCs and other types of temperature sensors may also be used. Likewise, the invention is not limited to circuit boards 58 with only one circuit board layer 84, but can also be applied to so-called multi-layer PCBs.

Claims

Claims 1. Energy storage unit (16) for an electrical consumer (10) with at least one first energy storage cell (20), at least one first temperature sensor (82) for detecting a temperature (T) of the at least one first energy storage cell (20) and a circuit board (58) for receiving the at least one first temperature sensor (82), characterized in that the at least one first temperature sensor (82) and the circuit board (58) are surrounded, in particular completely, by a temperature-conductive potting compound (60), wherein the temperature-conductive potting compound (60) is designed such that it comes into thermal contact with the at least one first energy storage cell (20), in particular at the location of the at least one first temperature sensor (82).

2. Energy storage unit (16) according to claim 1, characterized in that the at least one first temperature sensor (82) is arranged on a circuit board layer (84) of the circuit board (58) and the potting compound (60) on a side of the circuit board (58) opposite the circuit board layer (84) in the region of the at least one first temperature sensor (82) has a recess (92), in particular for thermally insulating the circuit board (58) and / or the at least one first temperature sensor (82) from a housing (14) of the energy storage unit (16) or of the electrical consumer (10).

3. Energy storage unit (16) according to claim 2, characterized in that the recess (92) is designed such that a cavity is formed between the potting compound (60) and the housing (14), which cavity defines a distance between the potting compound (60) and the housing (14) at least in the region of the at least one first temperature sensor (82).

4. Energy storage unit (16) according to one of the preceding claims, characterized in that a further temperature sensor (86) is arranged on the circuit board (58), which is spaced from the first temperature sensor (82) in such a way that it detects the temperature (T) of a further energy storage cell (20), wherein the further temperature sensor (86) is surrounded by the potting compound (60) in such a way that it comes into thermal contact with the further energy storage cell (20), in particular at the location of the further temperature sensor (86). Energy storage unit (16) according to one of the preceding claims, characterized in that the thermal contact surfaces (88) of the potting compound (60) are adapted to an outer contour (90) of the energy storage cells (20). Energy storage unit (16) according to one of the preceding claims, characterized in that the energy storage cells (20) are designed as cylindrical round cells and the thermal contact surfaces (88) of the potting compound (60) are designed to be complementary thereto, in particular concave. Energy storage unit (16) according to one of the preceding claims, characterized in that the potting compound (60) has at least one protruding contact point (94) for a housing (14) of the energy storage unit (16) or of the electrical load (10) on a side facing away from the at least one first energy storage cell (20).Energy storage unit (16) according to claim 7, characterized in that the potting compound (60) has two contact points (94), wherein the temperature sensors (82, 86) are arranged substantially centrally between the two contact points (94). Energy storage unit (16) according to one of the preceding claims, characterized in that the potting compound (60) is designed as an elastic thermoplastic. Energy storage unit (16) according to one of the preceding claims, characterized in that the circuit board (58) surrounded by the potting compound (60) is arranged on two adjacent energy storage cells (20) in such a way that it does not protrude beyond an envelope curve (80) formed by the two energy storage cells (20) in a cross-section. Electrical consumer (10) with an energy storage unit (16) according to one of the preceding claims.System comprising an electrical consumer (10) designed as a hand-held power tool (24) and at least one energy storage unit (16) designed as an interchangeable battery pack (26).

Images