Welding pattern of battery assembly connector

Abstract

A battery assembly includes a first battery cell having a first terminal, a bus bar connected to the first terminal, and a first weld bead for fixing the bus bar to the first terminal. The first weld bead includes a first end portion that continuously extends to a second end portion and is configured so that the first end portion faces in a direction toward the second end portion.

Description

Technical Field

[0001] The present disclosure relates to a battery assembly for an electric vehicle battery pack. An exemplary battery assembly includes a weld pattern configured to improve stress distribution and increase the strength and life of a battery cell terminal / bus bar joint. Background Art

[0002] The desire to reduce fuel consumption and emissions from motor vehicles has been well documented. As a result, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electric vehicles are currently being developed for this purpose. In general, electric vehicles differ from conventional motor vehicles in that they are selectively driven by one or more battery-powered electric motors. In contrast, conventional motor vehicles rely entirely on internal combustion engines to propel the vehicle.

[0003] High-voltage battery packs typically power the motors and other electrical loads of electric vehicles. Battery packs include multiple battery cells that store energy. Battery cells must be reliably connected to each other to achieve the voltage and power levels required to power these electrical loads. Bus bars are typically used to connect battery cells. Summary of the invention

[0004] In addition to other aspects, a battery assembly according to an exemplary aspect of the present disclosure includes a first battery cell having a first terminal, a bus bar connected to the first terminal, and a first weld bead for fixing the bus bar to the first terminal. The first weld bead includes a first end portion that extends continuously to a second end portion and is configured so that the first end portion faces in a direction toward the second end portion.

[0005] In another non-limiting embodiment of the foregoing battery assembly, the bus bar is connected to the second terminal of the second battery cell by a second weld bead.

[0006] In another non-limiting embodiment of any of the foregoing battery assemblies, the second weld bead includes a first end portion that extends continuously to the second end portion and is configured such that the first end portion faces in a direction toward the second end portion.

[0007] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first terminal is comprised of a first material and the bus bar is comprised of a second, different material.

[0008] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first material is copper and the second material is aluminum.

[0009] In a further non-limiting embodiment of any of the foregoing battery assemblies, the assembly includes a second weld bead for securing the bus bar to the first terminal.

[0010] In a further non-limiting embodiment of any of the foregoing battery assemblies, the second weld bead is positioned adjacent to and toward the first weld bead.

[0011] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first weld bead and the second weld bead both extend transversely across a portion of the width of the bus bar.

[0012] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first weld bead and the second weld bead both extend longitudinally along a portion of the length of the bus bar.

[0013] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first weld bead and the second weld bead form a double C weld pattern.

[0014] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first weld bead is substantially C-shaped.

[0015] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first weld bead extends along a non-linear path.

[0016] In a further non-limiting embodiment of any of the foregoing battery assemblies, the non-linear path extends from a first end portion toward one side of the bus bar, and then toward an end of the bus bar, and then toward an opposite side of the bus bar, and then toward an opposite end of the bus bar, and then back toward the first end portion before terminating at a second end portion.

[0017] In a further non-limiting embodiment of any of the foregoing battery assemblies, the non-linear path extends from a first end portion toward an end of the bus bar, and then toward one side of the bus bar, and then toward an opposite end of the bus bar, and then toward the opposite side of the bus bar, and then back toward the first end portion before terminating at a second end portion.

[0018] In a further non-limiting embodiment of any of the foregoing battery assemblies, the first terminal is a positive terminal or a negative terminal.

[0019] A method according to another exemplary aspect of the present disclosure includes, among other things, welding a bus bar to a first terminal of a battery cell using a welding pattern including at least one weld bead extending along a non-linear path.

[0020] In another non-limiting embodiment of the foregoing method, welding the bus bar to the terminal includes laser welding the bus bar to the terminal.

[0021] In another non-limiting embodiment of any of the foregoing methods, the weld pattern includes two weld beads facing each other.

[0022] In a further non-limiting embodiment of any of the foregoing methods, the two weld beads extend transversely across a portion of the width of the bus bar.

[0023] In a further non-limiting embodiment of any of the foregoing methods, the two weld beads extend longitudinally across a portion of the length of the bus bar.

[0024] The embodiments, examples and alternatives of the preceding paragraphs, claims or the following description and drawings include any of their various aspects or individual features, which can be made independently or in any combination. Features described in conjunction with one embodiment are applicable to all embodiments, unless these features are incompatible.

[0025] The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description.The drawings that accompany the detailed description can be briefly described as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 schematically illustrates a powertrain system for an electric vehicle;

[0027] Figure 2 A battery assembly for an electric vehicle is shown;

[0028] Figure 3 shows a welding pattern for welding a bus bar to a battery cell terminal according to a first embodiment of the present disclosure;

[0029] Figure 4 shows a welding pattern according to a second embodiment of the present disclosure;

[0030] Figure 5 shows a welding pattern according to a third embodiment of the present disclosure;

[0031] Figure 6 A welding pattern according to a fourth embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0032] The present disclosure details a battery assembly for use in an electric vehicle battery pack. An exemplary battery assembly includes a first battery cell having a first terminal, a bus bar, and a first weld bead for securing the bus bar to the first terminal. The weld bead includes a first end portion that extends continuously to a second end portion and is configured such that the first end portion faces in a direction toward the second end portion. The first weld bead can be part of a welding pattern configured to improve stress distribution and increase the strength of a battery cell terminal / bus bar joint. These and other features of the present disclosure are discussed in more detail in the following paragraphs of this detailed description.

[0033] Figure 1Schematically illustrated is a powertrain 10 for an electric vehicle 12. Although depicted as a Hybrid Electric Vehicle (HEV), it should be understood that the concepts described herein are not limited to HEVs and may extend to other electric vehicles, including, but not limited to, Plug-in Hybrid Electric Vehicles (PHEV), Battery Electric Vehicles (BEV), Fuel Cell Vehicles, etc.

[0034] In a non-limiting embodiment, the powertrain 10 is a power split powertrain that employs a first and a second drive system. The first drive system includes a combination of an engine 14 and a generator 18 (i.e., a first motor). The second drive system includes at least a motor 22 (i.e., a second motor), the generator 18, and a battery pack 24. In this example, the second drive system is considered to be the electric drive system of the powertrain 10. Both the first and second drive systems are capable of generating torque to drive one or more sets of vehicle drive wheels 28 of the electric vehicle 12. Although in Figure 1 A power split configuration is depicted in , but the present disclosure extends to any hybrid vehicle or electric vehicle including a full hybrid, parallel hybrid, series hybrid, mild hybrid, or micro hybrid.

[0035] The engine 14, which may be an internal combustion engine, and the generator 18 may be connected by a power transfer unit 30, such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, may be used to connect the engine 14 to the generator 18. In a non-limiting embodiment, the power transfer unit 30 is a planetary gear set including a ring gear 32, a sun gear 34, and a carrier assembly 36.

[0036] Generator 18 may be driven by engine 14 through power transfer unit 30 to convert kinetic energy into electrical energy. Generator 18 may alternatively be used as a motor to convert electrical energy into kinetic energy, thereby outputting torque to shaft 38 connected to power transfer unit 30. Because generator 18 is operatively connected to engine 14, the speed of engine 14 may be controlled by generator 18.

[0037] The ring gear 32 of the power transfer unit 30 can be connected to the shaft 40, and the shaft 40 is connected to the vehicle drive wheels 28 through the second power transfer unit 44. The second power transfer unit 44 can include a gear set having a plurality of gears 46. Other power transfer units may also be suitable. The gears 46 transfer torque from the engine 14 to the differential 48 to ultimately provide traction for the vehicle drive wheels 28. The differential 48 may include a plurality of gears capable of transferring torque to the vehicle drive wheels 28. In a non-limiting embodiment, the second power transfer unit 44 is mechanically connected to the shaft 50 through the differential 48 to distribute torque to the vehicle drive wheels 28.

[0038] The motor 22 can also be used to drive the vehicle drive wheels 28 by outputting torque to a shaft 52 that is also connected to the second power transfer unit 44. In a non-limiting embodiment, the motor 22 and the generator 18 cooperate as part of a regenerative braking system, where both the motor 22 and the generator 18 can be used as motors to output torque. For example, the motor 22 and the generator 18 can each output power to the battery pack 24.

[0039] The battery pack 24 is an exemplary electric vehicle battery. The battery pack 24 may be a high voltage traction battery pack that includes a plurality of battery assemblies 25 (i.e., a battery array or group of battery cells) capable of outputting electrical power to operate the motor 22, the generator 18, and / or other electrical loads of the electric vehicle 12. Other types of energy storage devices and / or output devices may also be used to power the electric vehicle 12.

[0040] In one non-limiting embodiment, the electric vehicle 12 has two basic operating modes. The electric vehicle 12 can be operated in an electric vehicle (EV) mode, in which the motor 22 is used for vehicle propulsion (usually without the assistance of the engine 14), thereby depleting the state of charge of the battery pack 24 to its maximum allowable discharge rate under certain driving modes / cycles. EV mode is an example of a charge-depleting mode of operation of the electric vehicle 12. During EV mode, the state of charge of the battery pack 24 can increase in certain circumstances, such as during regenerative braking. The engine 14 is generally off in the default EV mode, but can be operated as needed based on vehicle system conditions or with the operator's permission.

[0041] The electric vehicle 12 may additionally operate in a hybrid electric vehicle (HEV) mode, in which both the engine 14 and the motor 22 are used for vehicle propulsion. The HEV mode is an example of a charge-maintaining operating mode of the electric vehicle 12. During the HEV mode, the electric vehicle 12 may reduce the amount of propulsion use of the motor 22 in order to maintain the state of charge of the battery pack 24 at a constant or approximately constant level by increasing the propulsion force of the engine 14. In addition to the EV and HEV modes within the scope of the present disclosure, the electric vehicle 12 may also operate in other operating modes.

[0042] Figure 2 A battery assembly 25 that can be used in an electric vehicle is schematically shown. For example, the battery assembly 25 can be Figure 1 The battery assembly 25 is a component of the battery pack 24 of the electric vehicle 12. The battery assembly 25 includes a plurality of battery cells 56, which store energy for powering various electrical loads of the electric vehicle 12. Figure 2 A specific number of battery cells is depicted in FIG. 2 , but within the scope of the present disclosure, the battery assembly 25 may employ a greater or lesser number of battery cells. In other words, the present disclosure is not limited to Figure 2 The specific configuration shown in .

[0043] The battery cells 56 may be stacked side by side along a longitudinal axis A to construct a group of battery cells 56, sometimes referred to as a "battery stack". In one embodiment, the battery cells 56 are prismatic lithium-ion batteries. However, battery cells having other geometries (cylindrical, pouch, etc.) and / or other chemistries (nickel metal hydride, lead acid, etc.) may alternatively be used within the scope of the present disclosure.

[0044] The battery cell spacer 58 can be located between each adjacent battery cell 56 of the battery stack of the battery assembly 25. For example, a plurality of battery cells 56 and a plurality of battery cell spacers 58 can be arranged side by side in an alternating manner to construct the battery assembly 25. The spacer 58 may also be referred to as a partition or a separator. In one embodiment, the spacer 58 includes a heat-resistant and electrically isolating plastic and / or foam having a relatively high thermal insulation capability.

[0045] The battery cells 56 along with any supporting structures (eg, array frames, spacers, rails, walls, panels, bindings, etc.) may be collectively referred to as a battery assembly 25 . A battery pack 24 may include one or more battery assemblies 25 .

[0046] A pair of terminals 62 extend outwardly from the top surface 64 of each battery cell 56. In one embodiment, the terminals 62 are disposed near opposite ends of the top surface 64. One of the terminals 62 is a positive terminal (indicated by the symbol "+") and the other terminal 62 is a negative terminal (indicated by the symbol "-"). The battery cells 56 can be arranged so that each terminal 62 is disposed adjacent to a terminal of an adjacent battery cell including opposite polarity. Thus, the positive (+) terminal 62 is positioned near the negative (-) terminal 62 at both ends of the top surface 64 along the entire battery stack.

[0047] The battery assembly 25 may further include a plurality of bus bars 60 for electrically connecting the battery cells 56 of the battery assembly 25. Each bus bar 60 is connected to a positive (+) terminal 62 on one battery cell 56 and a negative (-) terminal 62 on an adjacent battery cell 56. In one embodiment, the terminal 62 is made of a first material and the bus bar 60 is made of a second different material. For example, the terminal 62 may be a copper terminal and the bus bar 60 may be an aluminum bus bar. In another embodiment, the positive (+) terminal 62 is an aluminum terminal, the negative (-) terminal 62 is a copper terminal, and the bus bar 60 is an aluminum bus bar. Other materials are also within the scope of the present disclosure.

[0048] One or more weld beads 68 may be used to secure the bus bar 60 to the terminal 62. In one embodiment, the bus bar 60 is laser welded to the terminal 62. However, other welding operations are contemplated within the scope of the present disclosure.

[0049] Static and fatigue strength tests and Computer-Aided Engineering (CAE) simulations have shown that high stress areas occur at the start and end points of the weld beads 68. To address this issue, the bus bar 60 can be connected to the terminal 62 using a unique weld pattern 66 consisting of one or more formed weld beads 68. The unique weld pattern 66 shown and described herein is designed to improve stress distribution and increase the strength of the battery cell terminal 62 / bus bar 60 joint. Figure 3-6 Various exemplary welding patterns for securing the bus bar 60 to the terminal 62 are described.

[0050] Figure 3 A first exemplary weld pattern 66 is shown for securing the bus bar 60 to the terminal 62. In one embodiment, the weld pattern 66 includes a first weld bead 68A and a second weld bead 68B. The weld beads 68A, 68B can be positioned near an overlap 70 between the bus bar 60 and the terminal 62. In one embodiment, a portion of the bus bar 60 is placed on top of a portion of the terminal 62 to form the overlap 70.

[0051] In one embodiment, each weld bead 68A, 68B is formed by welding on the busbar 60 side of the joint using a laser welding technique. The laser welding technique only requires access on one side of the joint to form the weld pattern 66. However, other welding techniques may alternatively be used to form the weld pattern 66.

[0052] Figure 3 The welding pattern 66 of the embodiment of the embodiment can be referred to as a double C welding pattern. In such a pattern, the first weld bead 68A and the second weld bead 68B are both generally C-shaped and positioned parallel to face each other. In one embodiment, the first weld bead 68A and the second weld bead 68B are arranged in a transverse configuration, wherein the weld beads 68A, 68B are arranged to extend primarily transverse to the longitudinal axis A1 of the bus bar 60. The weld beads 68A, 68B extend across a portion of the width of the bus bar 60 in the transverse configuration.

[0053] Each weld bead 68A, 68B may include a first end portion 72 that extends continuously along a non-linear path to a second end portion 74. For example, the non-linear path may form each weld bead 68A, 68B in a C-shape. However, other shapes are also contemplated within the scope of the present disclosure. The first end portion 72 and the second end portion 74 extend in a direction toward each other. This design effectively positions the start and end points of the weld bead 68A, 68B at a low stress area of ​​the bus bar 60 / terminal 62 joint.

[0054] In another embodiment, each weld bead 68A, 68B may be formed by moving the welding tool from the first end portion 72 toward the side 80 of the bus bar 60, then in a direction away from the other weld bead 68A, 68B, then in a direction toward the opposite side 82 of the bus bar 60, then in a direction back toward the other weld bead 68A, 68B, and then in a direction toward the first end portion 72 to form the second end portion 74. This is merely one example of how the weld bead 68A, 68B may be formed. The present disclosure is not intended to be limited to this exact weld bead configuration.

[0055] Figure 4 A second exemplary weld pattern 166 is shown for securing the bus bar 60 to the terminal 62. In this embodiment, the weld pattern 166 includes a single weld bead 168. The weld bead 168 may be positioned proximate the overlap 70 between the bus bar 60 and the terminal 62.

[0056] Figure 4 The welding pattern 166 of the embodiment of can be referred to as a single C welding pattern. In such a pattern, the weld bead 168 is generally C-shaped. In one embodiment, the weld bead 168 is arranged in a transverse configuration, wherein the weld bead 168 extends primarily transverse to the longitudinal axis A1 of the bus bar 60. The weld bead 168 extends across a portion of the width of the bus bar 60 in this transverse configuration.

[0057] The weld bead 168 includes a first end portion 172 that extends continuously along a non-linear path to a second end portion 174. The non-linear path may form a C-shape for the weld bead 168. The first end portion 172 and the second end portion 174 extend toward each other. The design also effectively positions the start and end points of the weld bead 168 at low stress areas of the bus bar 60 / terminal 62 joint.

[0058] Figure 5 Another exemplary weld pattern 266 for securing the bus bar 60 to the terminal 62 is shown. In one embodiment, the weld pattern 266 includes a first weld bead 268A and a second weld bead 268B. The weld beads 268A, 268B may be positioned near the overlap 70 between the bus bar 60 and the terminal 62.

[0059] Figure 5 The welding pattern 266 of the embodiment of is another exemplary double C welding pattern. In such a pattern, the first weld bead 268A and the second weld bead 268B are both generally C-shaped and are positioned parallel to face each other. In one embodiment, the first weld bead 268A and the second weld bead 268B are arranged in a longitudinal configuration, wherein the weld beads 268A, 268B are arranged to extend primarily parallel to the longitudinal axis A1 of the bus bar 60. The weld beads 268A, 268B thus extend across a portion of the length of the bus bar 60 in this longitudinal configuration.

[0060] Each weld bead 268A, 268B may include a first end portion 272 that extends continuously along a non-linear path to a second end portion 274. For example, the non-linear path may form a C-shape for each weld bead 268A, 268B. Other shapes are also contemplated within the scope of the present disclosure. The first end portion 272 and the second end portion 274 extend in a direction toward each other. This design also effectively positions the start and end points of the weld bead 268A, 268B at a low stress area of ​​the bus bar 60 / terminal 62 joint.

[0061] In another embodiment, each weld bead 268A, 268B may be formed by moving the welding tool from the first end portion 272 toward the end 90 of the bus bar 60, then in a direction away from another weld bead 268A, 268B, then in a direction toward the opposite end 92 of the bus bar 60, then in a direction toward another weld bead 268A, 268B, and then back in a direction toward the first end portion 272 before terminating at the second end portion 274. This is merely one example of how weld beads 268A, 268B may be formed, and the present disclosure is not intended to be limited to this exact weld bead configuration.

[0062] Figure 6Yet another exemplary weld pattern 366 is shown for securing the bus bar 60 to the terminal 62. In this embodiment, the weld pattern 366 includes a single weld bead 368. The weld bead 368 may be positioned proximate the overlap 70 between the bus bar 60 and the terminal 62.

[0063] Figure 6 The welding pattern 366 of the embodiment of can be referred to as a single C welding pattern. In such a pattern, the weld bead 368 is generally C-shaped. In one embodiment, the weld bead 368 is arranged in a longitudinal configuration, wherein it extends primarily parallel to the longitudinal axis A1 of the bus bar 60. The weld bead 368 extends across a portion of the length of the bus bar 60 in the longitudinal configuration.

[0064] The weld bead 368 includes a first end portion 372 that extends continuously along a non-linear path to a second end portion 374. The non-linear path may form a C-shape for the weld bead 368. The first end portion 372 and the second end portion 374 extend toward each other. This design effectively positions the start and end points of the weld bead 368 at low stress areas of the bus bar 60 / terminal 62 joint.

[0065] The unique welding pattern of the present disclosure effectively positions the start and end points of each weld bead at low stress areas of the busbar / terminal joint. The weld bead pattern optimizes stress distribution, resulting in a stronger joint exhibiting higher static strength. The exemplary welding pattern further increases the fatigue life of the joint, thereby improving the joint quality.

[0066] Although different non-limiting embodiments are shown as having specific components or steps, the embodiments of the present disclosure are not limited to those specific combinations. Some components or features in any non-limiting embodiment may be used in combination with features or components from any other non-limiting embodiment.

[0067] It should be understood that like reference numerals indicate corresponding or similar elements throughout the several drawings.It should be understood that although particular component arrangements are disclosed and illustrated in these exemplary embodiments, other arrangements may also benefit from the teachings of the present disclosure.

[0068] The above description should be interpreted as illustrative, rather than any limitation. It will be appreciated by those skilled in the art that some modifications may fall within the scope of the present disclosure. For these reasons, the following claims should be studied to determine the true scope and content of the present disclosure.

Claims

1. A battery assembly comprising: a first battery cell including a first terminal; a bus bar connected to the first terminal; and A first weld bead for fixing the bus bar to the first terminal, wherein the first weld bead includes a first end portion extending continuously to a second end portion and configured such that a terminal end of the first end portion faces in a direction toward a terminal end of the second end portion. 2 . The battery assembly of claim 1 , wherein the bus bar is connected to a second terminal of a second battery cell by a second weld bead.

3. The battery assembly of claim 2, wherein the second weld bead includes a first end portion, the first end portion of the second weld bead continuously extending to the second end portion of the second weld bead and configured such that the first end portion of the second weld bead faces in a direction toward the second end portion of the second weld bead. 4 . The battery assembly of claim 1 , wherein the first terminal is comprised of copper and the bus bar is comprised of aluminum.

5. The battery assembly of claim 1, comprising a second weld bead for securing the bus bar to the first terminal. 6 . The battery assembly of claim 5 , wherein the second weld bead is positioned adjacent to and toward the first weld bead. 7 . The battery assembly of claim 5 , wherein the first weld bead and the second weld bead both extend transversely across a portion of the width of the bus bar or both extend longitudinally along a portion of the length of the bus bar. 8 . The battery assembly of claim 5 , wherein the first weld bead and the second weld bead form a double C weld pattern.

9. The battery assembly of claim 1, wherein the first weld bead is C-shaped.

10. The battery assembly of claim 1, wherein the first weld bead extends along a non-linear path.

11. The battery assembly of claim 10, wherein the non-linear path extends from the first end portion toward one side of the bus bar, and then toward an end of the bus bar, and then toward an opposite side of the bus bar, and then toward an opposite end of the bus bar, and then back toward the first end portion before terminating at the second end portion.

12. The battery assembly of claim 10, wherein the nonlinear path extends from the first end portion toward the end of the bus bar, and then toward one side of the bus bar, and then toward the opposite end of the bus bar, and then toward the opposite side of the bus bar, and then back toward the first end portion before terminating at the second end portion.

13. The battery assembly of claim 1, wherein the first terminal is a positive terminal or a negative terminal.

14. A method for a battery assembly, comprising: A bus bar is welded to a first terminal of a battery cell using a welding pattern including at least one weld bead extending along a non-linear path, wherein the welding pattern includes a first weld bead, wherein the first weld bead includes a first end portion that extends continuously to a second end portion and is configured such that an end of the first end portion faces in a direction toward an end of the second end portion.

15. The method of claim 14, wherein welding the bus bar to the terminal comprises laser welding the bus bar to the terminal.

16. The method of claim 14, wherein the weld pattern further comprises a second weld bead, the first weld bead and the second weld bead facing each other.

17. The method of claim 16, wherein the first weld bead and the second weld bead extend transversely across a portion of the width of the bus bar.

18. The method of claim 16, wherein the first weld bead and the second weld bead extend longitudinally across a portion of the length of the bus bar.

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