Bus bar assembly

Abstract

The battery system (10) includes at least one battery cell (12, 14) and a bus bar assembly (16). The bus bar assembly (16) for an electric vehicle has a power distribution bus bar (18) and a connector (20). The bus bar (18) comprises a body that is at least partially hollow and made of a conductive material. As a result, the bus bar (18) has at least one conductive inner surface (22) and an air gap adapted to improve the cooling efficiency by natural convection, thereby achieving passive cooling.

Description

Technical Field

[0001] The present invention relates to a busbar assembly for power distribution in an electric vehicle. The field of the present invention is, more particularly, the field of hybrid or electric vehicles in which energy is stored in a battery.

Background Art

[0002] A busbar is a metal strip or bar that conducts electricity and is used for power distribution. Power distribution equipment, including switchboards, switching devices, and motor control centers, uses busbar conductors to connect circuit breakers and other protective devices to loads.

[0003] Automotive battery cells can be connected to a busbar, for example, to form battery modules and battery packs. A large power output is required for the power source of an electric vehicle such as a hybrid vehicle or an electric vehicle. When the current flow in and out of individual cells (i.e., single electrochemical units) is combined into a continuous larger assembly (such as modules and packs) of a plurality of such cells, the current or voltage increases, enabling the generation of the desired power output. In this context, larger module and pack assemblies are composed of one or more cells connected in series (for voltage increase), in parallel (for increased battery capacity), or both, and may include additional structures to ensure the proper installation and operation of these cells. In this type of power supply device, battery cells arranged adjacent to each other are electrically connected to each other by busbars made of a conductive material.

[0004] In a known method, in a power supply device where battery cells are electrically connected to each other via a bus bar assembly, a bus bar made of a conductive material is laminated on the electrode terminals (or electrode leads) of the battery cells via connectors, and the laminated portion of the bus bar is welded to the electrode terminals of the battery cells. With such a configuration, the battery cells can be connected to each other with a small electrical resistance. However, as the number of cells increases, the risk of overheating the battery due to the heat generated by the cells may further increase.

[0005] Therefore, it is important for the bus bar to have a structure that can ensure the rigidity required to withstand the electrodynamic stress generated by the flow of current during normal conduction on the one hand, and optimize the flow of heat on the other hand.

[0006] A bus bar assembly including bus bars having different shapes is known from the prior art.

[0007] For example, European Patent Application Publication No. 2324545 discloses a bus system for use in electrical distribution equipment. The bus system includes a pair of opposing bowl-shaped conductors and a bus bar forming an octagonal cross-section with an air gap formed therein. The air gap improves the cooling efficiency by natural convection by directly exposing more surface area of the conductor to the air flow.

[0008] European Patent Application Publication No. 1131868 discloses a bus bar having a C-shaped cross-section. The C-shaped cross-section enables a modular geometric shape.

[0009] However, with such a configuration, it is not possible to address the thermal management of the bus bar without degrading the performance of such a bus bar.

[0010] European Patent Application Publication No. 2626946 discloses a busbar module having a busbar with an active cooling system and a cover member. The busbar module 1 is attached to a battery pack 9 that is cooled by forced air cooling. A first vent hole defining an air gap is formed in the busbar, and a second vent hole is formed in the cover member. The first vent hole 11 and the second vent hole 73 form an air flow path that communicates from the upstream side to the downstream side in a predetermined air cooling direction in each busbar housing portion. Forced air cooling consumes battery power and presents a failure point in the form of a fan motor.

SUMMARY OF THE INVENTION

[0011] The present invention is intended to solve the above problems. Accordingly, the present invention provides a busbar assembly for an electric vehicle as set forth in claim 1, and this disclosure is directed to this busbar assembly for an electric vehicle. The busbar assembly has a busbar for power distribution and a connector. The busbar includes a body that is at least partially hollow and made of a conductive material, such that the busbar has at least one inner conductive surface and an air gap adapted to improve the cooling efficiency by natural convection. Thus, only a passive cooling system is used. The connector is disposed and / or connected on the inner conductive surface of the busbar, and the outer surface of the busbar is electrically insulated.

[0012] With such a design, the size of the busbar can be reduced without degrading performance. By natural convection, active cooling is not required, thus avoiding the drawbacks of the active cooling system. On the contrary, since the contact area is on the inner surface of the busbar body, the conductive surface area increases. Further, due to the hollow configuration, heat transfer to the environment increases. Since the amount of material used in manufacturing is reduced, both economic benefits and a lighter assembly are achieved. Finally, since the connection part is inside the busbar, the busbar remains safe even when touched on its outer surface and is adapted to maintain electrical insulation even in case of a fire.

[0013] In one embodiment, the body extends longitudinally along the longitudinal axis X between a first end and a second end, has a body length L, and the body includes a cavity that extends longitudinally through the body from the first end to the second end. The cavity thus passes through the body, increasing the conductive surface area and also increasing the air gap for natural convection.

[0014] In one embodiment, the body is of one-piece construction. The body is made of one piece and no joints are formed.

[0015] In one embodiment, the sleeve is an outer sleeve and the body further includes an inner sleeve. Thus, the natural cooling surface of the busbar is increased, thereby improving the cooling performance. Further, for the same current flow, less material is required.

[0016] In one embodiment, the cavity has a substantially circular or square or triangular cross-section.

[0017] In one embodiment, the body includes a side opening connected to the cavity. The side opening increases natural air convection. Air can flow freely between the gaps and is not trapped inside the cavity. The side opening enables natural air convection inside the cavity.

[0018] In one embodiment, the side opening extends longitudinally over a portion of the body length L. In another embodiment, the side opening is formed by a plurality of holes. However, in other embodiments, the side opening may have other shapes.

[0019] In one embodiment, the cavity is a first cavity and the body includes a second cavity. This increases the connection surface area without increasing the length of the busbar body. Moreover, with the two air gaps arranged in this way, natural convection is increased by exposing more surface area of the conductor directly to the air flow. The two air gaps communicate with each other, for example.

[0020] In one embodiment, the second cavity extends longitudinally through the body from a first end to a second end. The first and second cavities may each have an annular cross-section. For example, these cavities can be arranged concentrically around the longitudinal axis.

[0021] In one embodiment, the body has a substantially circular or square or triangular cross-section. With these shapes, an integral body (a body of one part without joints) having cavities can be easily manufactured.

[0022] The present invention also relates to a battery system comprising at least one battery cell and a busbar assembly according to any of the preceding claims, wherein the connector connects the electrode leads of the at least one battery cell to the busbar body.

[0023] The present invention and its advantages will be better understood by reading the following description given by way of example only and by referring to the accompanying drawings.

Brief Description of the Drawings

[0024]

Figure 1

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Figure 8C

Embodiments for Carrying Out the Invention

[0025] Embodiments of the present disclosure are best understood by reference to the drawings, where like reference numerals indicate identical or similar elements. It will be readily understood that the components of the disclosed embodiments can be arranged and designed in a wide variety of different configurations as generally described and illustrated in the figures of this specification. Accordingly, the following detailed description of the embodiments of the systems and methods of the present disclosure is not intended to limit the scope of the claimed present disclosure, but is merely representative of possible embodiments of the present disclosure.

[0026] FIG. 1 shows a part of an exemplary battery system 10. The battery system 10 includes a first battery component 12 and a second battery component 14. As shown, the battery components 12, 14 are connected in parallel. However, in other embodiments, some battery components may be provided connected in parallel or in series or both. A bus bar assembly 16 is used to connect the battery components in this parallel arrangement. FIG. 1 shows a first and a second bus bar assembly 16. Each bus bar assembly 16 is coupled to the battery components 12, 14. The battery components 12, 14 can be battery cells, battery modules, battery packs, or any battery sub - assembly.

[0027] Figures 2A - 8C show ten different embodiments of the busbar assembly 16 according to the present invention. The busbar assembly 16 according to the present invention comprises a power - distribution busbar 18 and a connector 20. The connector electrically connects the busbar 18 to the battery components 12, 14. The busbar 18 comprises a body made of a conductive material. The body extends longitudinally along a longitudinal axis X and has a body length L. The body is at least partially hollow and comprises an inner surface 22 and an outer surface 24. The hollow portion of the busbar body forms at least one air gap. The air gap improves the cooling efficiency of the busbar 18, and thus can also improve the cooling efficiency of the busbar assembly 16 by natural convection. Thus, passive cooling is enabled by the air gap and active cooling is not required. The air gap forms part of a passive - cooling configuration. The hollow portion is formed, for example, by a cavity 26. The inner surface 22 faces the cavity 26. The inner surface 22 defines the cavity 26. The inner surface 22 is, for example, not painted or coated and is thus a conductive surface. The outer surface 24 may be painted or coated or treated, or may comprise an additional layer, whereby this surface is electrically insulated. A side opening 28 is provided between the inner surface 22 and the outer surface 24. The side opening 28 may have different shapes as shown hereinafter. The connector 20 is at least partially disposed on the inner surface 22 of the busbar body. This can provide a compact busbar assembly and good electrical conductivity. The busbar body may be of an integral type. In other words, the busbar body may be formed by one single part and does not include any cut or joint. The body is, for example, a molded body or an extruded part. There is material continuity.

[0028] The cavity 26 may have different shapes or cross - sections, especially as shown in Figures 2A - 9C. The busbar 18 may have different cross - sectional shapes as shown in Figures 2A - 9C.

[0029] For example, in the first embodiment shown in FIGS. 2A and 2B, the bus bar 18 has a cylindrical shape with a circular cross section. More specifically, the bus bar body has an annular cross section. The cavity 26 extends throughout the entire body length L (in another variant of the present invention, the cavity may be a blind hole having a cavity length shorter than the body length). The lateral openings 28 are formed by a plurality of holes arranged on the bus bar body in the vicinity of the first and / or second free ends 30, 32. For example, three holes are provided at one end and the other three holes are provided at the other end.

[0030] FIGS. 3A and 3B show a second embodiment of the bus bar assembly 16 having a bus bar body with a circular cross section. The cavity 26 has an annular cross section such that the body comprises a core 181 and an outer sleeve 182, and the cavity 26 extends between the core and the outer sleeve. The core 181 is connected to the outer sleeve 182 at several connection points C1, C2 along the longitudinal axis X, for example. The core 181 is cylindrical and the outer sleeve 182 has an annular cross section. The core and the outer sleeve may be integral. For example, they form an extruded part.

[0031] The third embodiment shown in FIGS. 4A and 4B has a body comprising a core 181 and an outer sleeve 182. The core 181 and the outer sleeve 182 each have a rectangular cross section. The cavity 26 also has a rectangular cross section. The cavity 26 extends between the outer sleeve 181 and the sleeve 182. The lateral openings 28 are formed by longitudinal slits arranged on the bus bar body. The core 181 is connected to the outer sleeve 182 at several connection points C1, C2 along the longitudinal axis, for example. The core and the outer sleeve may be integral. For example, they form an extruded part.

[0032] In FIGS. 5A, 5B, 6A, and 6B, the cross-section of the body is triangular. The fourth embodiment of FIGS. 5A and 5B shows a hollow body, and in the fifth embodiment of FIGS. 6A and 6B, the body comprises a core 181 and a sleeve 182. Both have a triangular cross-section, and a cavity 26 extends therebetween. The side opening 28 is formed by a longitudinal slit disposed on the busbar body. The side opening 28 extends longitudinally only over a part of the body length L. The core 181 is connected to the outer sleeve 182 at several connection points C1, C2, for example, along the longitudinal axis X. The core and the outer sleeve may be integral. For example, they form an extruded part (only one body).

[0033] FIG. 7 is substantially similar to the embodiment of FIG. 3A, but shows a sixth embodiment in which the body also comprises an inner sleeve 183 between the core 181 and the outer sleeve 182. Thus, the cavity 26 may be in two parts (or in other words, there may be two cavities 261, 262). The first part (or the first cavity 261) extends between the core 181 and the inner sleeve 183, and the second part (or the second cavity 262) extends between the inner sleeve 183 and the outer sleeve 182. The first part and the second part are each substantially annular. The inner sleeve may be connected to the outer sleeve and the core at several connection points.

[0034] FIG. 8A shows a cross-sectional view of a seventh embodiment similar to the third embodiment of FIGS. 4A and 4B, where the body (and thus the outer sleeve 182) has a square cross-section. As shown, the core 181 has a rectangular cross-section, but in a variant, the core 181 may have a square cross-section.

[0035] The eighth embodiment disclosed in FIG. 8B comprises a hollow body having a square cross-section. The ninth embodiment comprises a hollow body having a rectangular cross-section.

[0036] In the second, third, fifth, sixth, and seventh embodiments, the presence of the core 181 can further increase the conductive surface, and thus improve the performance of the busbar assembly 16. However, such a core 181 also increases the amount of material and thus the weight. On the other hand, a completely hollow body (as shown in the first, fourth, eighth, and ninth embodiments) can increase the air gap and improve the cooling efficiency by natural convection of the busbar assembly. Thus, passive cooling is achieved, and in particular, the weight and size of the assembly can be limited.

[0037] The busbar assembly described above can be used in a battery system 10 as shown in FIG. 1. The busbar 18 is connected to at least a first battery component via a connector 20.

[0038] Battery system 10 First battery component 12 Second battery component 14 Busbar assembly 16 Busbar 18 Body length L Longitudinal axis X Connector 20 Inner surface 22 Outer surface 24 Cavity 26 Lateral opening 28 First and / or second free ends 30, 32 Core 181 Outer sleeve 182 Inner sleeve 183 First cavity 261 Second cavity 262 Connection points C1, C2

Claims

1. A bus bar assembly (16) for an electric vehicle having a bus bar (18) for power distribution, a connector (20), and a passive cooling configuration, wherein the bus bar (18) comprises a substantially hollow body made of a conductive material, such that the bus bar (18) comprises at least one conductive inner surface (22) and an air gap adapted to improve the cooling efficiency by natural convection, in the bus bar assembly (16). The passive cooling configuration is at least partially formed by the air gap, the connector (20) is disposed and / or connected to the inner surface (22) of the bus bar (18), and the outer surface (24) of the bus bar is electrically insulated. A bus bar assembly (16), characterized in that.

2. The body extends longitudinally along a longitudinal axis (X) between a first end and a second end, has a body length L, and the body comprises a cavity (26) extending longitudinally through the body from the first end to the second end, the bus bar assembly (16) according to claim 1.

3. The cavity (26) has a substantially circular or square or triangular cross-section, the bus bar assembly (16) according to claim 2.

4. The body comprises a side opening (28) connected to the cavity (26), the bus bar assembly (16) according to claim 2 or 3.

5. The side opening (28) extends longitudinally over a part of the body length L, the bus bar assembly (16) according to any one of claims 2 to 4.

6. The side opening (28) is formed by a plurality of holes, the bus bar assembly (16) according to any one of claims 2 to 4.

7. The cavity (26) is a first cavity (26), and the body comprises a second cavity (26), the bus bar assembly (16) according to any one of claims 2 to 6.

8. The second cavity (26) extends longitudinally through the body from the first end (30) to the second end (32), the bus bar assembly (16) according to claim 7.

9. The body comprises a core (181) and a sleeve (182), the bus bar assembly (16) according to any one of claims 1 to 8.

10. The busbar assembly (16) according to claim 9, wherein the sleeve is an outer sleeve (182) and the body further comprises an inner sleeve (183).

11. The busbar assembly (16) according to any one of claims 1 to 9, wherein the body is integral.

12. The busbar assembly (16) according to any one of claims 1 to 9, wherein the body has a substantially circular cross-section.

13. The busbar assembly (16) according to any one of claims 1 to 9, wherein the body has a substantially square cross-section.

14. The busbar assembly (16) according to any one of claims 1 to 9, wherein the body has a substantially triangular cross-section.

15. A battery system (10) comprising at least one battery component (12, 14) and the busbar assembly (16) according to any one of claims 1 to 14, wherein the connector (20) connects the battery component to the busbar (18).

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