SCREW-MOUNTED PRINCIPAL RAIL WITH FINGER GUARD

Description

[0001] The disclosure relates to a bus bar used to connect battery cells, for example.

[0002] A battery module has multiple battery cells with terminals that are electrically connected to one another to provide a more powerful battery than the individual cells would otherwise provide. One common type of electrical connection is a cable having terminal rings at opposing ends. Each terminal ring is bolted to one of terminals of one of the cells. Another common type of electrical connection is a bus bar that is bolted to the cells in a similar manner to that of the cable.

[0003] Publication US 5 576 516 A discloses a protective cover for a terminal includes a cover base for holding a terminal, a cover body for covering a terminal mounted on the cover base, the cover body including a freely operatable lid formed through a hinge and a temporary opening holding member for holding the freely operatable lid portion at a predetermined angle. Publication EP 0 765 005 A2 discloses a a cover including a pair of cover elements which are provided with receptacles for accommodating connection members of a battery connection terminal, and hollow connection portions which are slidably fitted so as to adjust the length of the cover The connection portions are openable, and the receptacles are provided with lids. After the connection portions are opened and partly assembled, the battery connection terminal is inserted into the cover sideways. Then, the connection portions are closed. The assembly of the cover and the terminal are fitted such that battery posts are inserted into insertion holes formed in the connection members, and the lids are closed after nuts are fastened to the battery posts. When a distance between the battery posts is changed, a corresponding battery connection terminal is prepared and the length of the cover is adjusted by sliding the connection portions with respect to each other. Accordingly, a slight change in the distance between the posts can be offset by the length adjustment of the woven wire and the cover. Publication US 2006 / 270277 A1 discloses an electrical terminal for electrical connections fanned from a metal stamping and including a coil spring interface. The electrical terminal includes a female terminal body having at least one opening for receiving an inserting portion of a male terminal body, the female terminal body including a stamped groove positioned about a perimeter of the opening; and a coil spring for providing an electrical interface between the inserting portion of the male terminal body and the female terminal body being positioned in the stamped groove.

[0004] The type of battery module used in, for example, automotive applications provides significant electrical energy. It is desirable to design a system for electrically connecting and disconnecting the cells in a manner that is safe for the battery module assembly and / or service technicians.

[0005] In one exemplary embodiment, a bus bar assembly includes, among other things, a nonconductive terminal cap that is configured to secure to an electrically conductive terminal via an attachment feature. The terminal cap has a slot that is configured to expose a terminal portion of the terminal in an assembled condition. A bus bar has an end that is configured to be received in the slot in the assembled condition in which the end is in electrical contact with the terminal portion of the terminal. A nonconductive shroud encloses the bus bar. The end extends through shroud.

[0006] The attachment feature includes at least one snap that is configured to be secured to a perimeter of a terminal pad that is provided by the terminal.

[0007] The assembly includes a bolt that extends through a first hole in the end of the bus bar and a second hole in the shroud. The terminal cap includes a third hole that is configured to be aligned with a threaded member of the terminal. The third hole is finger-proof per code IP2XB of International Electrotechnical Commission (IEC) standard 60529, and the threaded member is configured to receive the bolt in the assembled condition.

[0008] The shroud includes first and second shroud portions that are secured to one another about the bus bar. The second hole is provided in the second shroud portion. The first shroud portion includes an access hole that is finger-proof and is aligned with the bolt and configured to receive a tool that cooperates with a head of the bolt.

[0009] In a further embodiment of any of the above, the terminal cap includes a pair of the slot. The slot is finger-proof, and the end of the bus bar has a U-shape provided by legs. The legs are configured to be received in the slots and include a bolt that extends through the end and is configured to secure the bus bar to the terminal.

[0010] In a further embodiment of any of the above, the bolt is arranged between the legs.

[0011] In another exemplary embodiment, a battery module includes, among other things, a bus bar assembly according to any one of the above-described embodiments.

[0012] The battery module further comprises a first battery cell having the terminal provided by the terminal pad with the threaded member, and a second battery cell. The end is a first end, and the bus bar has a second end. The bolt is a first bolt, and includes a second bolt that secures the second end to the second battery cell.

[0013] In a further embodiment of any of the above, the terminal cap encloses the terminal pad except where the slot is finger-proof and exposes the terminal portion. The hole in the terminal cap exposes the threaded member.

[0014] In another exemplary embodiment, a method of electrically connecting cells of a battery includes, among other things, providing a bus bar assembly according to any one of the above-described embodiments. The method further comprises securing the nonconductive terminal cap over the terminal via the attachment feature, wherein the terminal cap includes the third hole and the slot exposing the terminal portion of the terminal. The end is located in the slot. The bolt is secured to the terminal by inserting the tool through the hole to clamp the end into engagement with the terminal.

[0015] The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: Figure 1 is schematic of a battery module having multiple battery cells electrically connected to one another with bus bars. Figures 2A and 2B are first and second perspective views of a first bus bar assembly. Figure 2C is a cross-sectional view of the first bus bar assembly taken along line 2C-2C in Figure 2B. Figure 3 is an exploded partial view of the first bus bar assembly. Figure 4A is a partial view of the first bus bar assembly in an unassembled condition with respect to a terminal. Figure 4B is cross-sectional view of the first bus bar assembly taken along line 4B-4B in Figure 2B. Figure 5A is cross-sectional view of the first bus bar assembly taken along line 5A-5A in Figure 2B with the first bus bar assembly connected to the terminal. Figure 5B is cross-sectional view of the first bus bar assembly taken along line 5B-5B in Figure 2B with the first bus bar assembly connected to a terminal.

[0016] The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. Like reference numbers and designations in the various drawings indicate like elements.

[0017] A battery module 10, or battery pack assembly, is schematically illustrated in Figure 1. The battery module 10 includes multiple battery cells 12 with positive and negative electrical terminals 14a, 14b (generally referred to as "terminal 14"). The terminals 14 of the various cells 12 are electrically connected to one another with bus bar assemblies 16 in a configuration that provides sufficient power for large electrical loads, such as automotive hybrid propulsion systems.

[0018] Referring to Figures 2A and 3, the terminal 14 is provided by a terminal pad 18 having a threaded member 20. In the example, the terminal pad 18 is an L-shaped copper structure, which provides a quadrangular outer surface 17 (Fig. 3) to which the bus bar assembly 16 is secured. Other terminal pad shapes may be used. The vertical portion (as depicted in the Figures) of the terminal pad 18 is arranged within the protective nonconductive housing of the cell 12, and is not shown for simplicity.

[0019] There is a potential shock hazard when the outer surface 17 of the terminal 14 is left exposed. To mitigate the shock hazard when connecting and disconnecting the bus bar assembly 16 from the cells 12, a nonconductive terminal cap 22 is secured to the terminal 14 via an attachment feature 24, for example, snaps. In the example, the snaps engage a perimeter 21 of the terminal pad 18 to retain the terminal cap 22 over the terminal 14. The perimeter 21 is arranged within and enclosed by the terminal cap 22, as best shown in Figure 2A.

[0020] The terminal cap 22 has a finger-proof slot 54 exposing a terminal portion 19 of the terminal pad 18 in an assembled condition, that is, with the terminal cap 22 secured to the terminal 14. In this disclosure, "finger-proof" means a configuration that meets the standard set forth in IEC 60529 entitled "Degrees of Protection Provided by Enclosures" and code IP2XB relating to finger Ingress Protection. The "test finger" is based upon a solid object 12.5 mm in diameter or more and up to 80 mm long being prevented from entering an enclosure. Furthermore, if a standard test finger 80 mm long and 12 mm in diameter enters the enclosure there will be adequate clearance from live parts, i.e., the terminal. In this manner, the disclosed finger-proof terminal cap 22 prevents a technician from inadvertently touching the terminal 14 with the terminal cap 22 in place, for example, during assembly and / or removal of the bus bar assembly 16 with respect to the cells 12.

[0021] An example bus bar assembly 16 is shown in Figures 2A-5B. The bus bar assembly 16 includes a bus bar 40 that is substantially enclosed by a nonconductive shroud 26 within a cavity 38. The shroud 26 includes first and second shroud portions 28, 30 secured about the bus bar 40. In the example illustrated, attachments 32 between the first and second shroud portions 28, 30 are provided by snaps 36 removably received in corresponding windows 34. Other attachments may be used if desired.

[0022] The bus bar 40 includes an end 52 that extends through a notch 50 provided at an end of the second shroud portion 30 to expose a small portion of the end 52. One such end 52 is provided at each of opposing ends of the bus bar assembly 16. The end 52 is sized to be received in the slot 54 in the assembled condition in which the end 52 is in electrical contact with the terminal pad 18. The complementary shapes of the end 52 and the slot 54 assist in easily locating the bus bar assembly 16 relative to the cells 12 during assembly.

[0023] A bolt 56 extends through a first hole 42 in the end 52 of the bus bar 40 and a second hole 44 in the second shroud portion 30. The terminal cap 22 includes a third hole 46 configured to be aligned with the threaded member 20 when the terminal cap 22 is installed over the terminal pad 18. The bolt 56 has first and second bolt portions 58, 59. An access hole 48 is aligned with a head of the bolt 56 provided on the first bolt portion 58. A tool, such as an Allen or Torx wrench for example, can be inserted through the access hole 48 to engage the bolt head. The second bolt portion 59 has threads that cooperate with the threaded member 20 to clamp the end 52 tightly to the terminal 14 when the bolt 56 is torqued to specification to make a good electrical connection.

[0024] When the bus bar assembly 16 is in an assembled condition, the shroud 26 and the terminal cap 22 cooperate to enclose the end 52 so that no portion of the bus bar 40 is left exposed. But, with the bus bar assembly 16 removed, the slot 54 and third hole 46 only exposes only very small terminal portions 19, which are finger-proof per code IP2XB and not susceptible to touching by the technician.

[0025] Various bus bar assembly and terminal cap configurations can be used to provide finger-proofing per code IP2XB. The example illustrated in Figures 2A-5B uses a pair of rectangular spaced apart slots 54. The end 52 of the bus bar 40 has a U-shape provided by legs 53. The legs 53 are received in the slots 54 and extend through the terminal cap 22 when in the assembled condition to make a mechanical and electrical connection. The bolt 56 extends through the end 52 and is arranged between the legs 53.

[0026] In operation, during assembly of the battery module 10, the nonconductive terminal cap is secured over each conductive terminal, for example, by snapping the terminal cap around the perimeter of the terminal. The terminal cap includes the finger-proof hole and the finger-proof slot exposing a small terminal portion of the terminal, both are finger-proof per code IP2XB. The nonconductive shroud encloses the bus bar with the end extending through shroud. With the bolt captured in the end by the shroud, the end is located in the slot and the bolt is disposed in the hole. The tool is inserted into the access hole in the shroud to engage the bolt, and the bolt is tightened to clamp the end into engagement with the terminal.

[0027] In this manner, the terminal cap can be permanently secured to the terminal, rendering the terminal finger-proof per code IP2XB. Thus, the battery module is finger-proof per code IP2XB even with the bus bar assemblies disconnected, which allows for safe assembly and handling of the battery module during assembly and servicing of the battery module.

Claims

1. A bus bar assembly (16) comprising: a nonconductive terminal cap (22) configured to secure to an electrically conductive terminal via an attachment feature (24), the terminal cap (22) has a slot (54) configured to expose a terminal portion (19) of the terminal (14) in an assembled condition, wherein the attachment feature (24) includes at least one snap configured to be secured to a perimeter (21) of a terminal pad (18) provided by the terminal (14); a bus bar (40) having an end (52) configured to be received in the slot (54) in the assembled condition in which the end (52) is in electrical contact with the terminal portion (19) of the terminal (14); a nonconductive shroud (26) enclosing the bus bar (40), with the end (52) extending through shroud (26); and a bolt (56) extending through a first hole (42) in the end (52) of the bus bar (40) and a second hole (44) in the shroud (26), the terminal cap (22) includes a third hole (46) configured to be aligned with a threaded member (20) of the terminal (14), the third hole (46) is finger-proof per code IP2XB of International Electrotechnical Commission (IEC) standard 60529, and the threaded member (20) configured to receive the bolt (56) in the assembled condition, wherein the shroud (26) includes first and second shroud portions (28, 30) secured to one another about the bus bar (40), the second hole (44) is provided in the second shroud portion (30), and the first shroud portion (28) includes an access hole (48) that is also finger-proof and is aligned with the bolt (56) and configured to receive a tool that cooperates with a head (58) of the bolt (56).

2. The bus bar assembly (16) of claim 1, wherein the terminal cap (22) includes a pair of the slot (54), wherein the slot (54) is finger-proof, and the end (52) of the bus bar (40) has a U-shape provided by legs (53), the legs (53) configured to be received in the slots (54), wherein the bolt (56) is configured to secure the bus bar (40) to the terminal (14).

3. The bus bar assembly (16) of claim 2, wherein the bolt (56) is arranged between the legs (53).

4. A battery module (10) comprising: the bus bar assembly (16) according to any of claims 1-3; a first battery cell (12) having the terminal (14) provided by the terminal pad (18) with the threaded member (20); and a second battery cell, wherein the end (52) is a first end, and the bus bar (40) has a second end, wherein the bolt (56) is a first bolt, and comprising a second bolt securing the second end to the second battery cell.

5. The battery module of claim 4, wherein the terminal cap (22) encloses the terminal pad (18) except where the slot (54) is finger-proof and exposes the terminal portion (19) and the hole (46) in the terminal cap (22) exposes the threaded member (20).

6. A method of electrically connecting cells (12) of a battery module (10), comprising the steps of: providing a bus bar assembly (16) according to any of claims 1 to 3; securing the nonconductive terminal cap (22) over the terminal (14) via the attachment feature (24), wherein the terminal cap (22) includes the third hole (46) and the slot (54) exposing the terminal portion (19) of the terminal (14); locating the end (52) in the slot (54); and securing the bolt (56) to the terminal (14) by inserting the tool through the access hole (48) to clamp the end (52) into engagement with the terminal (14).