DE102024204858A1 - Battery pack - Google Patents

Abstract

The invention relates to a battery pack, in particular a replaceable battery pack, with a housing in which at least one battery cell is arranged, and with electronics comprising at least one printed circuit board. It is proposed that the battery pack includes at least one spring element for heat dissipation and/or protection against electrical discharge, wherein the spring element is arranged on the printed circuit board such that the spring element contacts the housing.

Description

State of the art

In the DE 10 2022 206 663 A1 is a battery pack with a circuit board.

Disclosure of the invention

The invention relates to a battery pack, in particular a replaceable battery pack, comprising a housing in which at least one battery cell is arranged, and electronics comprising at least one printed circuit board. It is proposed that the battery pack include at least one spring element for heat dissipation and/or protection against electrical discharge, wherein the spring element is arranged on the printed circuit board such that it contacts the housing. Advantageously, this can improve the performance and/or safety of the battery pack.

The battery pack is, in particular, part of a system consisting of the battery pack and a load, the load being supplied with energy via the battery pack during operation. The battery pack can be, for example, a power tool battery pack or an e-bike battery pack. The battery pack is specifically designed as a replaceable battery pack, preferably one that can be detached from the load without tools. Alternatively, it is also conceivable that the battery pack is permanently attached to or integrated into the load's housing. The battery pack is, in particular, designed to be connectable to a charging device for recharging the battery pack. Alternatively or additionally, the battery pack can also be designed to be rechargeable while connected to the load.

The consumer may be trained in various ways, including as a garden tool, such as a lawnmower or hedge trimmer; as a household appliance, such as an electric window cleaner or handheld vacuum cleaner; as a power tool, such as an angle grinder, screwdriver, drill, hammer drill, etc.; as an electric means of transport, such as an electric bicycle in the form of a pedelec or e-bike, as an e-scooter; or as a measuring tool, such as a laser distance meter. Furthermore, it is also conceivable that the consumer may be trained in other, particularly portable, devices, such as construction site lighting, a dust extractor, or a construction site radio.

The battery pack has a housing in which the battery cells are contained. The battery pack housing is preferably designed as an outer casing. The battery pack, and in particular its housing, can be detachably connected to the load and/or a charging device via a mechanical interface, or it can be permanently connected. The battery pack housing can have one or more housing parts. The housing has at least one housing part that is designed as an outer casing part. Preferably, the housing consists entirely of outer casing parts. The outer casing part separates the battery pack from the outside and can be touched by a user. Furthermore, the housing can have at least one inner casing part that is completely enclosed by the at least one housing part. The battery pack housing can be made of a metallic material and/or a plastic.

The battery pack preferably includes a cell holder for receiving the battery cells. The cell holder of the battery pack is specifically designed as a housing component, preferably an inner housing component. However, it is also conceivable that the cell holder is partially or completely designed as an outer housing component. The housing of the battery pack can have one or more cell holders. The housing components, especially the cell holders, are connected to one another by force-fit, form-fit, and/or material-fit. The cell holder is preferably made of a plastic, particularly a thermoplastic. The cell holder is preferably made of a temperature-resistant plastic, preferably a fiber-reinforced plastic. Alternatively, it is also conceivable that the cell holder is made of a metallic material. The cell holder is specifically designed as a single piece. Other materials, such as ceramics, are also conceivable. In the context of this application, "single piece" is understood to mean, in particular, a component that is formed from a single piece and not from several components that are connected to one another by material-fit, force-fit, and/or form-fit. A one-piece component therefore consists of a single material. In the context of this application, "one-piece" is understood to mean several components that are joined together by a material bond, for example, via two-component injection molding or a material bond. A one-piece component can thus consist of one or more materials. Alternatively, it is also conceivable that the cell holder is designed in multiple parts, with the different parts being connected to each other by force-fit and/or form-fit. The battery pack can have one or more cell holders arranged side by side and/or one behind the other.

The battery pack can be connected to the load via a mechanical interface, either by force or form-fit. Advantageously, the mechanical interface includes at least one actuating element that allows the connection between the battery pack and the load and/or the charging device to be released. The actuating element can be, for example, a lock, a button, a lever, or a push button. The actuating element can be located on the battery pack or on the load. Furthermore, the mechanical interface can include guide elements for guiding the battery pack during the connection process and/or centering elements for centering the battery pack during the connection process.

Furthermore, the battery pack has at least one electrical interface through which it can be electrically connected to the load and/or the charging device. The battery pack can be charged and/or discharged via this electrical connection. Alternatively or additionally, it is also conceivable that information can be transmitted between the battery pack and the load via the electrical interface. The electrical interface is preferably designed as a contact interface, in which the electrical connection is made via a physical contact between at least two conductive components. The electrical interface preferably comprises at least two electrical contact elements. In particular, one of the electrical contact elements is designed as a positive contact and the other as a negative contact. Additionally, the electrical interface can have at least one auxiliary contact designed to transmit additional information to the load and/or the charging device. The auxiliary contacts can be designed as signal contacts, coding contacts, temperature contacts, bus contacts, etc. The electrical contact elements can be designed, for example, as spring-loaded contact elements in the form of contact tips or as flat contacts in the form of contact blades. Alternatively or additionally, the electrical interface can include a secondary charging coil element for inductive charging. The mechanical and electrical interfaces can be integrated or separate.

The electronics of the battery pack can include, in addition to the circuit board, components such as a processing unit, a control unit, a transistor, a capacitor, sensor elements, a light-emitting diode, a memory unit, etc. Additionally or alternatively, it is also conceivable that the electronics acquire information. The electronics are specifically designed to control or regulate the battery pack and/or the connected device. The electronics include, in particular, a BMS (Battery Management System) designed to monitor the battery pack. The BMS is specifically designed to prevent overcharging and/or deep discharging of the battery pack. Preferably, the BMS is designed to ensure correct cell balancing. The electronics can also include one or more sensor elements, for example, a temperature sensor to determine the temperature inside the battery pack or a motion sensor to detect movement. Alternatively or additionally, the electronics can include a coding element, such as a coding resistor. The electrical contact elements of the battery pack's electrical interface can be arranged on the circuit board of the electronics or connected to the circuit board. For the purposes of this application, a printed circuit board (PCB) is understood to be a circuit carrier comprising an organic or inorganic substrate, for example, IMS. The PCB can be rigid or flexible. Furthermore, the PCB can be populated or unpopulated. The PCB can be single-layer or multi-layered.

The battery cell can be designed as a galvanic cell with a structure in which one cell terminal is located at one end and another cell terminal at the opposite end. In particular, the battery cell has a positive cell terminal at one end and a negative cell terminal at the opposite end. Preferably, the battery cells are designed as NiCd or NiMH cells, and especially preferably as lithium-based or Li-ion battery cells. Alternatively, it is also conceivable, for example, that the battery cell is designed as a pouch cell or as a prismatic cell. The battery voltage of the battery pack is generally a multiple of the voltage of a single battery cell and results from the connection (parallel or series) of the battery cells. For common battery cells with a voltage of 3.6 V, exemplary battery voltages of 3.6 V, 7.2 V, 10 V, 8 V, 14.4 V, 18 V, 36 V, 54 V, 108 V, etc., result. Preferably, the battery cell is designed as a round cell that is at least substantially cylindrical, with the cell poles arranged at the ends of the cylindrical shape.

The at least one spring element is preferably formed in one piece, although a one-piece or multi-piece design is also conceivable. The spring element is preferably made of a metallic material, in particular steel. A design made of copper or a copper alloy would also be conceivable, which would optimize thermal conductivity. Alternatively, It is also conceivable that the spring element is made of an electrically and/or thermally conductive plastic. The spring element is designed, in particular, such that it exerts a force on the housing when assembled. The battery pack can have a single spring element, two spring elements, or several spring elements. The spring elements can be separate from each other or connected to one another. The spring element makes direct contact with the housing, so that it rests directly against the housing.

Furthermore, it is proposed that the spring element be electrically conductive. In particular, the spring element is electrically connected to the electronics. Advantageously, this provides effective protection against electrical discharge. Preferably, the spring element is connected to ground via the electronics. Alternatively, it would also be conceivable that the spring element is not electrically connected to the electronics. It is conceivable, by way of example, to provide at least two spring elements, one of which is designed for heat dissipation and the other for protection against electrical discharge.

It is further proposed that the electronics comprise at least two power semiconductors, in particular field-effect transistors, with the spring element being arranged in close proximity to the power semiconductors, especially between the field-effect transistors. This advantageously optimizes heat dissipation. Alternatively, it would also be conceivable for the electronics to comprise a single power semiconductor.

Furthermore, it is proposed that the spring element be bonded to the circuit board, particularly via a soldering process. This advantageously allows for a robust connection between the spring element and the circuit board. Alternatively, other joining techniques are also conceivable, such as welding, clipping, or screwing.

Furthermore, it is proposed that the housing have a contact surface for the spring element on its inner surface. This can advantageously improve heat dissipation and/or the electrical connection. The contact surface is specifically designed to be free of an oxide layer. The housing can be designed such that, during the assembly process, the housing is removed at the contact surface by friction between the spring element and the housing. Alternatively, the housing can also be cleaned of the oxide layer at the contact surface location before assembly.

It is further proposed that the spring element has a force-bearing section designed such that, during assembly, the housing exerts a force on the force-bearing section, thereby causing the spring element to deform, particularly elastically. Preferably, the force-bearing section is designed to create line contact between the housing and the spring element. This advantageously optimizes the connection for heat dissipation and/or protection against electrical discharge.

Furthermore, it is proposed that the spring element has two force-absorbing sections that are designed separately from each other. This advantageously ensures contact so that even if damaged during assembly, at least one part of the spring element remains in contact with the housing.

Furthermore, it is proposed that the force-absorbing section be arranged on a region of the spring element opposite the circuit board. This advantageously optimizes the contact with the housing.

It is further proposed that the force-bearing section be designed such that the housing can be mounted by sliding it along the printed circuit board. The printed circuit board spans a plane, with the sliding action occurring essentially parallel to this plane. Alternatively, it would also be conceivable for the sliding action to occur at an angle or perpendicular to this plane.

Furthermore, it is proposed that the spring element be U-shaped or S-shaped in cross-section. This advantageously allows for further optimization of the connection to the housing through improved tolerance compensation.

Drawings

Further advantages arise from the following drawing description. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations. Features of alternative embodiments are identified with the same reference numeral and an additional letter that characterizes the embodiment.

• 1 eine perspektivische Ansicht eines Elektrofahrrads mit einem erfindungsgemäßen Akkupack;
• 2 eine perspektivische Ansicht eines beispielhaften Akkupacks;
• 3 eine perspektivische Ansicht einer Leiterplatte des Akkupacks nach 2;
• 4 ein Seitenschnitt des Akkupacks nach 2;
• 5 ein Seitenschnitt einer weiteren Ausführungsform eines Federelements während der Montage;
• 6 eine perspektivische Ansicht einer weiteren Ausführungsform eines Federelements.

They show:

• 1 a perspective view of an electric bicycle with a battery pack according to the invention;
• 2 a perspective view of an example battery pack;
• 3 a perspective view of a circuit board of the battery pack 2 ;
• 4 a side section of the battery pack after 2 ;
• 5 a side section of another embodiment of a spring element during assembly;
• 6 a perspective view of another embodiment of a spring element.

Description of the exemplary implementations

In 1 A consumer 10 with a battery pack 100 is shown in a perspective side view. The consumer 10 is designed as an example of an electrically powered means of transport 12, in particular as an electric bicycle 14. The electric bicycle 14 can be designed, for example, as a pedelec or as an e-bike.

The electric bicycle 14 has a frame 18, or bicycle frame. Two wheels 20 are connected to the frame 18. The consumer 10 also has a drive unit 22, which includes an electric motor. The electric motor is preferably a permanent magnet excited, brushless DC motor. The electric motor is shown as a mid-drive motor, although a hub motor or the like is also conceivable.

The drive unit 22 includes a control unit (not shown) designed to control or regulate the electric bicycle 14, in particular the electric motor. The electric bicycle 14 has a pedal crank 24. The pedal crank 24 is connected to a pedal crank axle (not shown).

The control unit and the drive unit 22, comprising the electric motor and the crank axle, are arranged in a drive housing 26 connected to the frame. The drive motion of the electric motor is preferably transmitted to the crank axle via a gearbox (not shown), with the degree of assistance provided by the drive unit 22 being controlled or regulated by the control unit.

The consumer 10 is electrically and mechanically connected to the battery pack 100, which is designed to supply energy to the drive unit 22. The battery pack 100 is shown, by way of example, as a replaceable battery pack 102. In its connected state, the battery pack 100 is shown, by way of example, fully integrated into the frame 18 of the electric bicycle 14. The connection can be made by axially inserting the battery pack 100 into the down tube of the frame 18 or by pivoting the battery pack 100 laterally into the frame 18. Alternatively, it is also conceivable that the battery pack 100 is designed such that it can be attached to an outside of the frame 18, for example, to the down tube or the seat tube.

In 2 Figure 1 shows a perspective view of the battery pack 100. The battery pack 100 has a housing 104, which is designed as an outer housing. The housing 104 has, for example, a base body 105, which extends between two end plates 103, the end plates 103 terminating the base body 105 at its ends. The base body 105 has, for example, a rectangular cross-section and extends substantially over the entire length of the battery pack 100. The base body 105 is, for example, made of a metallic material, for example, aluminum.

The battery pack 100 has a charge level indicator 106, which is arranged on the housing 104 of the battery pack 100 and is designed to indicate the charge level of the battery pack 100. Furthermore, the housing 104 of the battery pack 100 is connected to two connecting plates 108. The connecting plates 108 are shown screwed to the housing 104 of the battery pack 100 by way of example; however, it would also be conceivable that the connecting plates 108 are connected to the housing 104 by a different type of connection or are formed integrally with the housing 104 of the battery pack 100. The first connecting plate 110 includes a locking unit 113, which can be connected to a corresponding locking unit (not shown) of the electric bicycle 14. The second connecting plate 112 includes an electrical interface (not shown) for the electrical connection of the battery pack 100 to the electric bicycle 14. It is also conceivable that the connecting plates 108 and the end plates 103 are formed in one piece or as a single unit.

In 3 A printed circuit board 200 of the electronics 202 of the battery pack 100 is shown in a perspective view. The printed circuit board 200 includes several electronic components 204 as examples.

Furthermore, the circuit board 200 has two spring elements 206 designed for heat dissipation and/or protection against electrical discharge. The spring elements 206 have a substantially U-shaped cross-section and are shown soldered to the circuit board 200.

The spring elements 206 have a width 210 that corresponds to at least 50% of the width 212 of the printed circuit board 200. The spring elements 206 are arranged on the printed circuit board 200 such that they contact the housing 104 of the battery pack 100. To make contact with the housing 104 of the battery pack 100, each spring element 206 has at least one force-bearing section 214, which comes into contact with the housing 104 during assembly and on which a force acts, causing the spring element 206 to deform, in particular elastically. To increase the elasticity of the spring elements 206, they have a recess 218 between a printed circuit board connection area 216, in which the spring elements 206 are connected to the printed circuit board 200, and the force-bearing section 214. The recess 218 has a maximum width of approximately 30% of the width 210 of the spring elements 206, whereby the recess 218 continuously decreases and closes in the direction of the force-absorbing section 214. As a result, each spring element 206 has a single force-absorbing section 214, the width of which essentially corresponds to the width 210 of the spring elements 206.

The spring elements 206 are designed differently in their function as examples, although it would also be conceivable that the two spring elements 206 are designed for the same function.

The first spring element 220, which is arranged at the end face of the circuit board 200, is designed essentially solely for protection against electrical discharge. For this purpose, the first spring element 220 is electrically connected to the circuit board 200, in particular to ground. The first spring element 220 is a single piece and is made of steel.

In 4 The second spring element 222 is shown in a side section in its assembled state. The second spring element 222 is not electrically connected to the circuit board 200 and therefore is not designed for protection against electrical discharge. The second spring element 222 is designed to dissipate heat generated by electronic components 204 that produce a high temperature.

As an example, the second spring element 222 is arranged in close proximity to a power semiconductor 224 in the form of a field-effect transistor. Specifically, the second spring element 222 is arranged such that the power semiconductor 224 is essentially completely covered. For example, there is no air gap between the power semiconductor 224 and the second spring element 222, so that the spring element 222 is in direct contact with the electronic component 224, and in particular, is subjected to a voltage. However, it would also be conceivable that the second spring element 222 does not directly contact the power semiconductor 224 and that an air gap is arranged between the components. Alternatively or additionally, it is also conceivable to use a thermally conductive material, for example, thermal paste, to improve heat dissipation and to fill the air gap. For example, the second spring element 222 is made of copper or a copper alloy to further improve heat dissipation.

A plurality of battery cells 101, for example cylindrical cells, are arranged in the housing 104 of the battery pack 100. The battery cells 101 are arranged in cell holders 103, which are designed, for example, to hold the individual battery cells 101. The cell holders 103 are, for example, made of a plastic, in particular a hard plastic. The circuit board 200 is arranged between the cell holder 103 and the housing 104, in particular the base body 105 of the housing 104. In particular, the battery cells 101 are arranged substantially parallel to the circuit board 200.

During assembly of the housing 104, the base body 105 is slid onto the cell holders 103, which are equipped with battery cells 101, and the circuit board 200 along a connection direction 230. This connection direction 230 runs essentially parallel to the circuit board 200. The force-absorbing section 214 of the spring elements 206 has a slope 232 that extends obliquely to the connection direction 230 and moves upon contact with the base body 105 of the housing 104. This movement pushes the force-absorbing section 214 towards the circuit board 200, generating a preload force on the housing 104 of the battery pack 100.

The housing 104 of the battery pack 100, in particular the base body 105 of the housing 104, has, for example, two contact surfaces 234 against which the spring elements 206 bear when assembled. The contact surfaces 234 can be optimized with regard to the function of the spring elements 206. For example, the contact surface 234 of the first spring element 220 (not shown) is freed from an oxide layer, in particular an anodized layer, so that the electrical connection is improved.

In 5 An alternative embodiment of a spring element 206a is shown in cross-section, wherein the spring element 206a is shown before contact with the base body 105a of the battery pack 100a. The spring element 206a is exemplary. Designed for heat dissipation and protection against electrical discharge. The S-shaped design improves the elastic properties of the spring element 206a.

In 6 Another alternative embodiment of a spring element 206b is shown in a perspective view. The spring element 206b is designed for heat dissipation and protection against electrical discharge.

The spring element 206b is, by way of example, made of copper and electrically connected to the circuit board (not shown). The spring element 206b has, by way of example, several, in particular two, force-absorbing sections 214b, which are designed to contact two different contact surfaces of the battery pack. The force-absorbing sections 214b are separated from each other by a recess 218b, the recess 218b being wider than the respective force-absorbing sections 214b. Advantageously, a higher defect tolerance can be achieved by using several force-absorbing sections 214b.

Furthermore, the printed circuit board interconnection area 216b is designed in such a way that several electronic components, for example two or three electronic components, can be covered.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 10 2022 206 663 A1 [0001]

Claims (14)

Battery pack, in particular a replaceable battery pack, with a housing (104) in which at least one battery cell (101) is arranged, with electronics (202) which has at least one circuit board (200), characterized in that the battery pack (100) has at least one spring element (206) for heat dissipation and/or for protection against electrical discharge, wherein the spring element (206) is arranged on the circuit board (200) such that the spring element (206) contacts the housing (104). Battery pack after Claim 1 , characterized in that the spring element (206) is electrically conductive. Battery pack after Claim 2 , characterized in that the spring element (206) is electrically connected to the electronics (202). Battery pack according to one of the preceding claims, characterized in that the electronics (200) comprise at least two power semiconductors (224), in particular field-effect transistors, wherein the spring element (206) is arranged in the immediate vicinity of the power semiconductors (224), in particular between the field-effect transistors. Battery pack according to one of the preceding claims, characterized in that the spring element (206) is materially bonded to the circuit board (200), in particular via a soldering process. Battery pack according to one of the preceding claims, characterized in that the housing (104), in particular at least one housing part of the housing (104), is made of a metallic material. Battery pack according to one of the preceding claims, characterized in that the housing (104) has a contact surface (234) on its inside for the spring element (206). Battery pack according to one of the preceding claims, characterized in that the spring element (206) has a force receiving section (214) which is designed such that it is subjected to a force during assembly by the housing (104) and the spring element (206) is thereby deformed in a particularly elastic manner. Battery pack after Claim 8 , characterized in that spring element (206) has two force-absorbing sections (214) which are designed separately from each other. battery pack after one of the Claims 8 until 9 , characterized in that the force receiving section (214) rests against the housing (104) in the assembled state and exerts a force on the housing (104). battery pack after one of the Claims 8 until 10 , characterized in that the force receiving section (214) is arranged on a region of the spring element (206) opposite the circuit board (200). battery pack after one of the Claims 8 until 11 , characterized in that the force receiving section (214) is designed such that the housing (104) can be mounted by sliding the housing (104) along the circuit board (200). Battery pack according to one of the preceding claims, characterized in that the spring element (206) has a U-shaped cross-section. Battery pack according to one of the preceding claims, characterized in that the spring element (206) has an S-shaped cross-section.