DE102024204866A1 - 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 received, wherein the battery pack has at least two components that are in contact with each other and are force-fit together. It is proposed that at least one of the components, in particular both components, has a surface modification designed to increase the contact force between the components.

Description

State of the art

In the DE 10 2020201165 A1 is described a battery arrangement with a plurality of battery cells, wherein a tension anchor is provided for applying a preload force to a battery pack.

Disclosure of the invention

The invention relates to a battery pack, in particular a replaceable battery pack, with a housing in which at least one battery cell is received, wherein the battery pack has at least two components that are in contact with each other and are force-fit together. It is proposed that at least one of the components, in particular both components, has a surface modification designed to increase the contact force between the components. Advantageously, this can increase the robustness of the battery pack.

The battery pack is, in particular, part of a system comprising the battery pack and a device, the device 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 device without tools. Alternatively, it is also conceivable that the battery pack is permanently attached to or integrated into the device'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 device.

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 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 via 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 configured to transmit additional information to the load and/or the charging device. The auxiliary contacts can be configured as signals. The electrical contact elements can be configured as contacts, coding contacts, temperature contacts, bus contacts, etc. These electrical contact elements can be, for example, spring-loaded contact elements in the form of contact tulips or 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.

In particular, the battery pack includes electronic components. These electronic components may include, for example, a circuit board, 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 electronic components acquire information. The electronic components are specifically designed to control or regulate the battery pack and/or the connected device. The electronic components 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 electronic components may also include one or more sensor elements, such as a temperature sensor to determine the temperature inside the battery pack or a motion sensor to detect movement. Alternatively or additionally, the electronic components may include a coding element, such as a coding resistor. The electrical contact elements of the battery pack's electrical interface may be arranged on the circuit board of the electronic components 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.

In the context of this application, a surface modification shall be understood to mean, in particular, a surface modification that is formed integrally with the component. The surface modification is thus formed from the same material as the component.

In the context of this application, a contact force is understood to mean, in particular, a force required to separate the two components. The contact force is specifically a frictional force.

Furthermore, it is proposed that at least one of the components be designed as a cell holder for receiving the battery cells, and that the cell holder has the surface modification. Alternatively or additionally, one of the components can be designed as an intermediate plate, wherein the intermediate plate has the surface modification.

The cell holder of the battery pack is designed, in particular, as a housing component, preferably as an inner housing component. However, it is also conceivable that the cell holder is designed partially or completely as an outer housing component. The housing of the battery pack can have one or more cell holders. The housing components, in particular the cell holders, are connected to one another by force-fit, form-fit, and/or material bonding. The cell holder is preferably made of a plastic, in particular a hard plastic, preferably 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, in particular, designed as a single piece. Other materials, for example 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 by material bonding and/or force-fit and/or form bonding. The components are formed in a way that is intrinsically connected to one another. 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 materially connected to one another, 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 formed in multiple parts, with the different parts being connected to one another by force and/or form-fitting. The battery pack has several cell holders that are arranged next to each other and/or one behind the other.

The intermediate plate is specifically designed as an inner housing component that is arranged at the end face of one or two cell holders. The intermediate plate preferably rests partially against the cell holder or directly against the cell holder. The intermediate plate is preferably made of the same material as the cell holder, although other materials, such as plastic, metal, or ceramic, are also conceivable.

It is further proposed that at least one of the components be configured as a cell connector for electrically contacting the battery cell, wherein the cell connector has the surface modification. The cell connector is configured for electrically contacting at least one battery cell. The cell connector preferably rests against the battery cell, in particular against an electrically conductive area of the battery cell, for example, a cell terminal. The cell connector can be made, for example, of a metal sheet, a cable, or a wire. Preferably, the cell connector is made of a metal sheet, wherein the cell connector partially or substantially completely covers at least one battery cell, preferably several battery cells, at their end faces. The cell connectors are preferably formed in one piece or as a single component. The cell connectors are preferably made of aluminum, steel, copper, or nickel, or an alloy of at least one of these materials. The cell connector can have a spring element for selectively increasing the elasticity of the cell connector, wherein the spring element is preferably formed integrally with the cell connector. In addition, the cell connector can have a fusible link.

Furthermore, it is proposed that the surface modification be designed as an area of increased roughness, in which the roughness depth is at least 10 µm, in particular at least 15 µm, preferably at least 20 µm. Advantageously, this allows for further optimization of the contact force. The roughness depth is preferably classified according to VDI guideline 3400. The roughness depth can be classified as an Rmax class or an Rz class. With the Rmax class, a maximum roughness depth of a surface is determined, independent of the average roughness depth. With the Rz class, an average roughness depth is determined.

Furthermore, it is proposed that the surface modification comprises a multitude of interlocking structural elements which, in the connected state, at least partially penetrate the corresponding component. Advantageously, this allows for further optimization of the contact force. The interlocking structural elements are preferably defined, such that the surface modification is formed by a multitude of essentially identical interlocking structural elements. Alternatively, it is also conceivable that the interlocking structural elements are randomly and undefinedly formed.

Furthermore, it is proposed that the intervention structure elements be pyramid-shaped and/or triangular. This would advantageously allow for further optimization of the contact force.

Furthermore, it is proposed that the surface modification be produced using an electrical discharge machining (EDM) technique. This allows for the targeted and cost-effective application of surface modifications to the components.

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.

• 1 eine perspektivische Ansicht eines Elektrofahrrads mit einem Akkupack;
• 2 eine perspektivische Ansicht eines beispielhaften Akkupacks;
• 3 eine perspektivische Ansicht eines Zellenhalters des Akkupacks, der mittels Oberflächenmodifikationen mit Zwischenplatten verbunden wird;
• 4a eine schematische Ansicht einer möglichen Ausführungsform der Oberflächenmodifikation;
• 4b eine schematische Ansicht zweiter Komponenten, die ohne Oberflächenmodifikation miteinander verbunden sind;
• 5 eine schematische Ansicht eines Zellverbinders des Akkupacks, der über eine Oberflächenmodifikation mit einer Akkuzelle verbunden ist.

They show:

• 1 a perspective view of an electric bicycle with a battery pack;
• 2 a perspective view of an example battery pack;
• 3 a perspective view of a cell holder of the battery pack, which is connected to intermediate plates by means of surface modifications;
• 4a a schematic view of a possible embodiment of the surface modification;
• 4b a schematic view of two components connected without surface modification;
• 5 A schematic view of a cell connector of the battery pack, which is connected to a battery cell via a surface modification.

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 end plates 103 of the housing 104 are, for example, made of a plastic, in particular a hard plastic.

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 cell holder 200 is shown, arranged in the housing 104 of the battery pack 100. The battery pack 100 has, by way of example, five cell holders 200, with an intermediate plate 210 arranged between the cell holders 200. By way of example, an intermediate plate 210 is arranged on each end face of the cell holders 200 of the battery pack 100, closing off the end faces of the cell holders 200. The cell holder 200 and the intermediate plates 210 are, by way of example, made of a plastic, in particular a hard plastic.

The cell holder 200 is designed to hold battery cells 202. The cell holder 200 is designed, by way of example, to hold ten battery cells 202. The battery cells 202 are designed, by way of example, as cylindrical round cells, which extend along their longitudinal extent between two cell poles 220 (see 5 extend.

The cell holder 200 is designed to accommodate individual cells, so that the battery cells 202 are arranged individually and separately from one another in separate cell holders 204. The cell holder 200 is, by way of example, made of a plastic, in particular a glass fiber reinforced hard plastic. The cell holder 200 is also designed in two parts, although a one-piece design would also be conceivable.

The battery pack 100 also includes cell connectors 206 for electrically connecting the battery cells 202. For example, each battery cell 202 is connected to a cell connector 206, particularly at its end face at the cell terminal 220. The cell connector 206 is, for example, made of a metallic material, in particular a metal sheet. The battery cells 202 are connected to each other in parallel or in series via the cell connectors 206. The cell connector 206 is, for example, designed such that it is positively and detachably connected to the battery cells 202. The preload is applied by an elastic spring element 208, which is, for example, made of a foam 209, in particular Poron, wherein the elastic spring element 208, in the connected state, bears directly against the cell connector 206 and is deformed. The elastic spring elements 208 are, for example, arranged on the intermediate plates 210. The intermediate plate 210 is formed in one piece, wherein the elastic spring elements 208 are materially bonded to a base plate 211 made of hard plastic.

The cell holders 200 are axially pressed together by means of fastening elements (not shown), which are exemplified as tie rods. In the assembled state, the cell holders 200 rest directly against contact surfaces 214 of the intermediate plates 210 via contact surfaces 211. The contact surface 214 of the intermediate plate 210 extends continuously along the contour of the intermediate plate 210. The contact surface 211 of the cell holder 206 extends, by example, intermittently along the contour of the cell holder 206.

The cell holder 200 and the intermediate plates 210 each have surface modifications 212 designed to increase the contact force between the components 215 of the battery pack 100 in the form of the cell holder 200 and the intermediate plate 210.

The surface modification 212 is exemplified as a micro-serration 216 and in 4a schematically represented. The surface modification 212, in particular the micro-serration 216, is formed integrally with the respective components 215. For example, the surface modification 212, in particular the micro-serration 216, can be produced using a targeted electrical discharge machining (EDM) technique. The surface modification 212 is designed such that the roughness depth, in particular according to an Rz class, lies in the range between 18 and 20 µm. The micro-serration 216 is undefined and randomly formed.

Advantageously, the surface modification 212 of the components 215 can significantly increase the contact force, especially the torsional stiffness, which also allows for a reduction in the thickness of the components. 4b For comparison, two components 215a with a standard and significantly lower roughness depth of the respective contact surfaces 211a, 214a are shown, which have a significantly higher material thickness in order to achieve the same contact force, in particular torsional stiffness.

In 5 Figure 1 shows a schematic view of the cell connector 206 in the state connected to a cell pole 220 of a battery cell 202.

The single-cell receptacle 204 of the cell holder 200 has, by way of example, radial fixing elements 222, which are designed for radially fixing the battery cells 202 in the cell holder 200. The radial fixing elements 222 are preferably made of an elastic plastic, for example, a soft plastic.

The cell holder 200 also has a fixed bearing 224, wherein the fixed bearing 224 is, by way of example, formed integrally with the cell holder 200. The fixed bearing 224 is, by way of example, designed as a pin 226 which engages in a corresponding recess in the cell connector 206 and holds the cell connector 206, by way of example, essentially perpendicular to a plane of the cell connector 206, in a form-fitting manner.

The cell connector 206 also features a relative play compensation element 228, which is designed to compensate for play between the force-fit connected components 215 in the form of the battery cell 202 and the cell connector 206. The relative play compensation element 228 is, by way of example, formed integrally with the cell connector 206, in particular by means of targeted material weakening by means of recesses.

The cell connector 206 has a contact area 230 in which the cell connector 206 directly abuts the cell terminal 220 of the battery cell 202. On one side facing the battery cell 202, the cell connector 206 has a surface modification 212 in the contact area 230 to increase the contact force.

The surface modification 212 of the cell connector is exemplified as an engagement structure element 232. The engagement structure element 232 is particularly designed as a micro-claw 234. Preferably, the cell connector 206 is made of a harder material than the cell pole 220 of the battery cell 202, such that the micro-claw 234, under the influence of force in the direction of the battery cell 202, engages in the cell pole 220, preferably by digging into a softer surface layer of the cell pole 220.

The micro-claw 234 is exemplified as a pyramidal structure with a triangular form, although other structures are also conceivable. Advantageously, the micro-claw requires no process heat, unlike a material-bonded connection achieved through, for example, a conventional welding process between the battery cell and the cell connector. The claw thus advantageously increases the contact force, particularly the frictional force, between the cell connector 206 and the battery cell 202, resulting in a significantly optimized, force-fit, and therefore detachable connection between the components 215.

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 2020201165 A1 [0001]

Claims (8)

Battery pack, in particular a replaceable battery pack, with a housing (104) in which at least one battery cell (202) is received, wherein the battery pack (200) has at least two components (215) that are in contact with each other and are force-fit together, characterized in that at least one of the components (215), in particular both components (2152), has a surface modification (212) designed to increase a contact force between the components (215). Battery pack according to one of the preceding claims, characterized in that at least one of the components (215) is designed as a cell holder (206) for receiving the battery cells (202) and has the surface modification (212). Battery pack according to one of the preceding claims, characterized in that at least one of the components (215) is designed as an intermediate plate (210) and has the surface modification (212). Battery pack according to one of the preceding claims, characterized in that at least one of the components (215) is designed as a cell connector (206) for electrical contacting the battery cell (202). Battery pack according to one of the preceding claims, characterized in that the surface modification (212) is designed as an area of increased roughness in which a roughness depth of at least 10 µm, in particular at least 15 µm, preferably at least 20 µm, is located. Battery pack according to one of the preceding claims, characterized in that the surface modification (212) has a plurality of engagement structure elements (232) which, in the connected state, at least partially penetrate into the corresponding component (215). Battery pack according to one of the preceding claims, characterized in that the engagement structure elements (232) are pyramid-shaped and/or triangular. Battery pack according to one of the preceding claims, characterized in that the surface modification (212) is produced by means of an erosion technique.