Flat-design battery assembly for electrically powered vehicles

Abstract

Battery assembly (54) comprising: several battery cells (58) positioned on a cooling plate; a support structure (59) positioned above the several battery cells (58), the support structure (59) comprising at least one side wall (62); and the at least one side wall (62) comprising a first flange (70) extending adjacent to an upper surface (74) of each of the several battery cells (58), and a second flange (72) extending beyond a lower surface (76) of each of the several battery cells (58) to a position adjacent to a side of the cooling plate (66); and the assembly (54) comprising a trough (88) and the at least one side wall (62) attached to the trough (88), characterized in that the at least one side wall (62) is attached to one of the two, a trough (88) or a cooling plate (66), by means of a weld bead (82).

Description

INVENTION AREA This disclosure relates to a battery assembly for an electrically powered vehicle. The battery assembly comprises a battery array with at least one side wall that is attached along a span of the assembly to either a trough or a cooling plate in order to maintain contact between the battery array and the cooling plate for improved thermal performance. GENERAL STATE OF THE ART The need to reduce motor vehicle fuel consumption and emissions is widely recognized. Therefore, vehicles are being developed that either reduce or completely eliminate reliance on an internal combustion engine. Electrically powered vehicles are one type of vehicle designed for this purpose. Generally, electric vehicles differ from conventional motor vehicles in that they are selectively powered by one or more battery-powered electric motors. In contrast, conventional motor vehicles rely entirely on the internal combustion engine to propel the vehicle. High-voltage batteries for powering the electric motors of an electric vehicle typically contain multiple battery arrays. Each battery array contains several battery cells and a support structure (i.e., end walls and side walls) that generally surrounds the battery cells to form the battery array. A cooling plate may be positioned along one underside of the battery cells to thermally direct the heat generated by the battery cells. In publication US 2013 / 0004822A1, a battery assembly comprising several battery cells and a support structure positioned over the multiple battery cells is described, the support structure including a side wall. The side wall includes a first flange extending adjacent to an upper surface of each of the multiple battery cells and a second flange extending beyond a lower surface of each of the multiple battery cells. Further relevant prior art relating to the background of the invention is provided in publications US 2014 / 0220391A1, DE 102012223144A1, and DE 102011018183A1. BRIEF DESCRIPTION OF THE INVENTION A battery assembly according to an exemplary aspect of the present disclosure comprises, among other things, several battery cells and a support structure positioned around the several battery cells. The support structure comprises at least one side wall. The at least one side wall comprises a first flange extending adjacent to an upper surface of each of the several battery cells, and a second flange extending beyond a lower surface of each of the several battery cells. In the aforementioned assembly, the multiple battery cells are positioned on a cooling plate. The second flange is adjacent to one side of the cooling plate and is attached to the side. In a further, non-restrictive embodiment of the aforementioned assemblies, a thermally conductive interface material is compressed between the cooling plate and the multiple array racks. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the at least one side wall includes a first height that is greater than a second height of the multiple battery cells. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the support structure includes opposing end walls and opposing side walls. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the first flange encompasses a portion of the upper surface of each of the multiple battery cells. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the first flange extends in a plane transverse to the second flange. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the first flange extends in a first plane, and the second flange extends in a second plane that is parallel to the first plane. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the second flange contains at least one opening. In a further, non-restrictive embodiment of one of the aforementioned assemblies, a fastening element is received in the at least one opening in order to fasten the at least one side wall to a cooling plate. The assembly includes a trough, and at least one side wall is attached to the trough. In a further, non-restrictive embodiment of one of the aforementioned assemblies, at least one side wall contains a body extending between the first flange and the second flange. The second flange includes a flared section that widens outwards from the body. The multiple battery cells are positioned on a cooling plate. At least one side wall is attached with a weld bead to one of the two, a trough or a cooling plate. A battery assembly according to another exemplary aspect of the present disclosure comprises, among other things, a trough, a cooling plate positioned on the trough, and a battery array with multiple battery cells positioned on the cooling plate. The battery array includes a side wall attached to one of the two, the trough or the cooling plate, and extending beyond a lower surface of each of the multiple battery cells. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the side wall includes a first flange that encompasses part of an upper surface of each of the multiple battery cells. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the side wall includes a second flange extending to a position adjacent to one side of the cooling plate. In a further, non-restrictive embodiment of one of the aforementioned assemblies, the side wall is attached to one of the two, the trough or the cooling plate, by at least one fastening element. The side wall is attached to one of the two, the trough or the cooling plate, by at least one weld bead. The embodiments, examples, and alternatives in the preceding paragraphs, the claims, or the following description and drawings, including each of their various aspects or corresponding individual features, may be included independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible. The various features and advantages of this disclosure will become apparent to experts from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically illustrates a powertrain of an electrically powered vehicle. Fig. 2 illustrates a battery assembly of an electrically powered vehicle according to a first embodiment of this disclosure. Fig. 3 illustrates a side view of a battery assembly. Fig. 4 illustrates features associated with a side wall of a battery array. Fig. 5 illustrates a battery assembly according to a second embodiment of this disclosure. Fig. 6 illustrates a battery assembly according to a third embodiment of this disclosure. Fig. 7 illustrates a battery assembly according to another embodiment of this disclosure. Fig. 8 illustrates a battery assembly according to yet another embodiment of this disclosure. DETAILED DESCRIPTION This disclosure describes in detail a battery assembly for an electric vehicle. The battery assembly may include multiple battery cells and a support structure positioned around the battery cells to form a battery array. The support structure includes one or more side walls with an extension piece that extends beyond a lower surface of each of the multiple battery cells. The extension piece may be attached to either a cooling plate or a trough of the battery assembly using a variety of fastening techniques. The exemplary battery assemblies in this disclosure provide flat array cooling plate / trough fastenings along one span of the array to achieve optimal thermal performance. This and other features are explained in more detail in the following paragraphs. Fig. 1 schematically illustrates a powertrain 10 for an electrically powered vehicle 12. Although shown for a hybrid electric vehicle (HEV), it should be understood that the concepts described here are not limited to HEVs and may extend to other electrically powered vehicles, including, but not limited to, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel cell vehicles. In one embodiment, the powertrain 10 is a power-split powertrain system employing a first drive system and a second drive system. The first drive system comprises a combination of an internal combustion engine 14 and a generator 18 (i.e., a first electric machine). The second drive system comprises at least one electric motor 22 (i.e., a second electric machine), the generator 18, and a battery 24. In this example, the second drive system is considered an electric drive system of the powertrain 10. The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels 28 of the electrically powered vehicle 12. Although a power-split configuration is shown, this disclosure extends to all hybrid or electric vehicles, including full hybrids, parallel hybrids, series hybrids, mild hybrids, or micro hybrids. The internal combustion engine 14, which in one embodiment is an internal combustion engine, and the generator 18 can be connected by a transfer case 30, such as a planetary gear set. Of course, other types of transfer cases, including other gear sets and transmissions, can be used to connect the internal combustion engine 14 to the generator 18. In a non-limiting embodiment, the transfer case 30 is a planetary gear set comprising a ring gear 32, a sun gear 34, and a carrier assembly 36. The generator 18 can be driven by the internal combustion engine 14 via the transfer case 30 to convert kinetic energy into electrical energy. Alternatively, the generator 18 can function as an electric motor to convert electrical energy into kinetic energy, thereby delivering torque to a shaft 38 connected to the transfer case 30. Because the generator 18 is operationally connected to the internal combustion engine 14, the speed of the internal combustion engine 14 can be controlled by the generator 18. The ring gear 32 of the transfer case 30 can be connected to a shaft 40, which is connected to the vehicle drive wheels 28 via a second transfer case 44. The second transfer case 44 can contain a gear set comprising several gears 46. Other transfer cases may also be suitable. The gears 46 transmit torque from the internal combustion engine 14 to a differential 48 to ultimately provide traction for the vehicle drive wheels 28. The differential 48 can contain several gears that enable the transmission of torque to the vehicle drive wheels 28. In one embodiment, the second transfer case 44 is mechanically coupled to an axle 50 via the differential 48 to distribute torque to the vehicle drive wheels 28. The electric motor 22 can also be used to drive the vehicle's drive wheels 28 by delivering torque to a shaft 52, which is also connected to the second transfer case 44. In one embodiment, the electric motor 22 and the generator 18 act together as parts of a brake energy recovery system, in which both the electric motor 22 and the generator 18 can be used as electric motors to deliver torque. For example, both the electric motor 22 and the generator 18 can deliver any electrical power to the battery 24. Battery 24 is an exemplary type of battery for an electrically powered vehicle. Battery 24 may contain a high-voltage traction battery assembly comprising multiple battery arrays capable of supplying electrical power to operate the electric motor 22 and the generator 18. Other types of energy storage devices and / or energy delivery devices may also be used to supply electrical power to the electrically powered vehicle 12. In a non-restrictive embodiment, the electrically powered vehicle 12 has two essential operating modes. The electrically powered vehicle 12 can be operated in an electric vehicle (EV) mode, in which the electric motor 22 is used to propel the vehicle (generally without assistance from the internal combustion engine 14), thereby discharging the state of charge of the battery 24 to its maximum permissible discharge rate under certain driving patterns / cycles. The EV operating mode is an example of a discharge operating mode for operating the electrically powered vehicle 12. Under certain conditions, the state of charge of the battery 24 may increase during EV mode, for example, due to a period of regenerative braking. In a standard EV operating mode, the internal combustion engine 14 is generally switched off; however, it could be operated as required, based on a vehicle system state or as permitted by the operator. The electrically powered vehicle 12 can additionally be operated in a hybrid (HEV) mode, in which both the internal combustion engine 14 and the electric motor 22 are used for vehicle propulsion. The HEV mode is an example of a charge maintenance mode for operating the electrically powered vehicle 12. In HEV mode, the electrically powered vehicle 12 can reduce the use of the electric motor 22 for propulsion in order to maintain the state of charge of the battery 24 at a constant or nearly constant level by increasing the use of the internal combustion engine 14 for propulsion. Within the scope of this disclosure, the electrically powered vehicle 12 can be operated in other modes in addition to the EV and HEV modes. Fig. 2 illustrates a battery assembly 54 that can be installed in an electrically powered vehicle. For example, the battery assembly 54 could be used as part of the battery 24 of the electrically powered vehicle 12 from Fig. 1. The battery assembly 54 contains one or more battery arrays 56 to supply electrical power to components of an electrically powered vehicle. Although a single battery array 56 is illustrated in Fig. 2, the battery assembly 54 could contain multiple battery arrays 56 within the scope of this disclosure. In other words, this disclosure is not limited to the specific configuration shown in Fig. 2. The battery array 56 contains multiple battery cells 58 and a support structure 59 positioned around the multiple battery cells 58. The battery cells 58 can be stacked side by side along a span L of the battery array 56 and can extend between opposing end walls 60 and side walls 62 of the support structure 59. In one embodiment, the support structure 59 generally surrounds the battery array 56 on at least four sides. To assemble the battery array 56, the side walls 62 of the support structure 59 can be connected to the end walls 60 using one or more fasteners 64. In one embodiment, the battery cells are 58 prismatic lithium-ion cells. However, other types of battery cells, including but not limited to cylindrical or pouch cells, could alternatively be used within the scope of this disclosure. The battery assembly 54 may additionally include a cooling plate 66. The battery array 56 may be positioned on a cooling plate 66. The cooling plate 66 serves to dissipate heat generated by the battery cells 58 under certain conditions. In one embodiment, the cooling plate 66 is a structurally cast cooling plate. In another embodiment, the cooling plate 66 is a stamped cooling plate. It is understood that the cooling plate 66 can be manufactured using any technique and any material that adequately compensates for the bending moment that may develop between the side walls 62 of the battery array 56 along the span L. In another embodiment, the end walls 60 are attached to the cooling plate 66 using additional fasteners 64. Now, with reference to Figures 2 and 3: One or both of the side walls 62 of the battery array 56 can include a first flange 70, a second flange 72, and a body 75 extending between the first flange 70 and the second flange 72. The first flange 70 abuts an upper surface 74 of the battery cells 58, and the second flange 72 abuts a lower surface 76 of the battery cells 58. The body 75 of the side walls 62 can optionally include several openings 77 (see Figure 2) to reduce the weight of the battery array 56. In one embodiment, the side walls 62 of the support structure 59 include a first height H1, which is greater than a height H2 of the battery cells 58 (best illustrated in Fig. 3). The first flange 70 can encompass a portion of the upper surfaces 74 of the battery cells 58, extending toward the opposite side wall 62. The first flange 70 exerts a compressive force against the battery cells 58 to maintain uniform contact between the battery cells 58 and the cooling plate 66. A seal 99 can be positioned between the first flange 70 and the upper surfaces 74 of the battery cells 58 (see Fig. 2). In another embodiment, the first flange 70 extends in a plane P that is transverse to both the body 75 and the second flange 72 of the side walls 62 (see Fig. 3). The second flange 72 extends beyond the lower surface 76 of each of the battery cells 58, or, in this example, below them. The second flange 72 therefore extends to a position adjacent to a side 80 of the cooling plate 66. In a non-restrictive embodiment, the second flange 72 can be attached to one or both side walls 62 along a span L on the cooling plate 66. This can be done using a variety of fastening techniques. In one embodiment, the second flange 72 is welded to the cooling plate 66 using one or more weld beads 82. Either a continuous weld bead 82 extending along all or part of the span L, or several individual weld beads 82 spaced apart along the span L, can be used to mount the side wall 62 to the cooling plate 66.Suitable welding techniques include, but are not limited to, laser welding, metal inert gas welding, spot welding, projection welding, etc. In another embodiment, one or more fasteners can be used to attach the side wall 62 to the cooling plate 66 (see, for example, Fig. 6, which is discussed in more detail below). Fig. 4 illustrates additional features of a side wall 62 of the battery assembly 54. In one embodiment, the second flange 72 of the side wall 62 includes a flared portion 86 that widens outwards (i.e., in a direction away from the battery cells 58) with respect to the body 75 of the side wall 62. The flared portion 86 reduces the complexity of assembling the battery assembly 54 by simplifying the placement of the battery array 56 over the cooling plate 66. The flared portion 86 has sufficient flexibility to allow the second flange 72 to be pressed or bent into a position that is flush with the cooling plate 66. Fig. 5 illustrates parts of another exemplary battery assembly 154. Where appropriate, in this disclosure identical reference numbers denote identical elements, and reference numbers to which 100 or multiples thereof are added denote modified elements which are to be understood as including the same features and advantages as the corresponding original elements. In this embodiment, a thermally conductive interface material (TIM) 68 can be positioned between the cooling plate 66 and the battery array 56 of the battery assembly 154. In one embodiment, the TIM 68 is compressed between the cooling plate 66 and the battery array 56. The TIM 68 can be made of a material with relatively high thermal conductivity and is designed to maintain thermal contact between the battery cells 58 and the cooling plate 66 in order to increase the thermal conductivity between these adjacent components during a heat transfer event. For example, the TIM 68 can distribute heat over the entire contact surface between the battery cells (not shown) of the battery array 56 and the cooling plate 66. The TIM 68 can extend over the entire cooling plate 66 or over individual parts. Fig. 6 illustrates another exemplary battery assembly 254. In this embodiment, the side walls 262 of a battery array 256 are connected to the cooling plate 266 by one or more fasteners 90. The fasteners 90 can be threaded fasteners or any other type of mechanical fastener. A second flange 272 of the side walls 262, or the portion of the side walls 262 extending beyond a lower surface 276 of the battery cells 258, can include one or more openings 92. The openings 92 are aligned with corresponding openings 94 in the cooling plate 266 during the assembly of the battery assembly 254. The fasteners 90 can be received in the openings 92 and the openings 94 to attach the side walls 262 to the cooling plate 266.In one embodiment, the openings 92 and the openings 94 are distributed along an entire span L of the battery assembly 254. Figures 2-6 illustrate battery assemblies that include sidewall-cooling plate mountings. However, the battery array could be mechanically attached to other structures of a battery assembly. Figure 7, for example, illustrates a battery assembly 454 that includes a battery array 456 mounted on a trough 88. In one embodiment, the sidewalls 462 of the battery array 456 are welded to the trough 88 by means of one or more weld beads 482. A cooling plate 466 can be enclosed between the trough 88 and the battery array 456. In this embodiment, the sidewalls 462 include a first flange 470 and a second flange 472, which are transverse to each other. The weld beads 482 can be placed between the second flanges 472 and the trough 88. Fig. 8 illustrates a battery assembly 554 similar to the battery assembly 454 shown in Fig. 8. In this embodiment, the side walls 562 of a battery array 556 include a first flange 570 and a second flange 572. The first flange 570 extends in a first plane P1, and the second flange 572 extends in a second plane P2, which is parallel to the first plane P1. The first flange 570 and the second flange 572 extend from a body 575 of the side walls 562 in opposite directions. The side walls 562 are attached to the trough 88 along the second flanges 572 and can be either welded or mechanically fastened using fasteners. Although the different non-limiting embodiments are illustrated by showing specific components or steps, the embodiments of this disclosure are not limited to these particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. It is understood that in the various drawings, identical reference numbers consistently denote corresponding or similar elements. Although a particular component arrangement is disclosed and illustrated in these embodiments, it is understood that other arrangements could also benefit from the teachings of this disclosure. The foregoing description should be interpreted as illustrative and not as limiting in any way. An average person would understand that certain modifications could fall within the scope of protection of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.

Claims

Battery assembly (54) comprising: several battery cells (58) positioned on a cooling plate; a support structure (59) positioned above the several battery cells (58), the support structure (59) comprising at least one side wall (62); and the at least one side wall (62) comprising a first flange (70) extending adjacent to an upper surface (74) of each of the several battery cells (58), and a second flange (72) extending beyond a lower surface (76) of each of the several battery cells (58) to a position adjacent to a side of the cooling plate (66); and the assembly (54) comprising a trough (88) and the at least one side wall (62) attached to the trough (88), characterized in that the at least one side wall (62) is attached to one of the two, a trough (88) or a cooling plate (66), by means of a weld bead (82). Assembly (54) according to claim 1, comprising a thermally conductive intermediate layer material (68) that is compressed between the cooling plate (66) and the multiple battery cells (58). Assembly (54) according to claim 1, wherein the at least one side wall (62) has a first height which is greater than a second height of the multiple battery cells (58). Assembly (54) according to claim 1, wherein the support structure (59) comprises opposing end walls (60) and opposing side walls (62). Assembly (54) according to claim 1, wherein the first flange (70) encompasses a part of the upper surface (74) of each of the multiple battery cells (58). Assembly (54) according to claim 1, wherein the first flange (70) extends in a plane transverse to the second flange (72). Assembly (54) according to claim 1, wherein the first flange (70) extends in a first plane (P1) and the second flange (72) extends in a second plane (P2) which is parallel to the first plane (P1). Assembly (54) according to claim 1, wherein the second flange (72) contains at least one opening (92). Assembly (54) according to claim 8, comprising a fastening element (90) which is received in the at least one opening (92) to fasten the at least one side wall (62) to a cooling plate (66). Assembly (54) according to claim 1, wherein the at least one side wall (62) contains a body (75) extending between the first flange (70) and the second flange (72), wherein the second flange (72) contains a flared part (86) that flares outwards from the body (75). Battery assembly (54) comprising: a trough (88); a cooling plate (66) positioned on the trough (88); and a battery array (56) containing several battery cells (58) positioned on the cooling plate (66), wherein the battery array (56) includes a side wall (62) attached to one of the two, the trough (88) or the cooling plate (66), and extending beyond a lower surface (76) of each of the several battery cells (58), characterized in that the side wall (62) is attached to one of the two, the trough (88) or the cooling plate (66), by at least one weld bead (82). Assembly (54) according to claim 11 wherein the side wall (62) includes a first flange (70) which encompasses a part of an upper surface (74) of each of the multiple battery cells (58). Assembly (54) according to claim 12, wherein the side wall (62) includes a second flange (72) extending to a position adjacent to a side of the cooling plate (66).

14. Assembly (54) according to claim 11, wherein the side wall (62) is attached to one of the two, the trough (88) or the cooling plate (66), by at least one fastening element (90).

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