Mounting frame for a traction battery of an electric vehicle

Abstract

A mounting frame for a traction battery of an electric vehicle, comprising a plurality of peripheral frame members (Figure 1; 14, 16) and a plurality of spaced apart elongate cell support frame member

Description

TECHNICAL FIELD The present disclosure relates to a mounting frame for a traction battery of an electric vehicle. Aspects of the invention relate to a traction battery assembly for an electric vehicle comprising a mounting frame of the traction battery and to a vehicle comprising a traction battery assembly of the invention. BACKGROUND It is known to provide a vehicle battery which either forms part of a battery module that is integrated into the vehicle frame (known as “cell to chassis”) or in the form of a battery stack directly included in a battery pack without being divided into individual modules (known as “cell to pack” or “C2P”). In cell to chassis designs, the battery module is structural in that it is designed to bear forces and contributes to the strength and / or rigidity of the vehicle in which it is fitted. However, in cell to pack designs the battery stack is non-structural in that it is not designed to bear significant forces, does not form part of the structure of the vehicle in which it is to be fitted, does not contribute to the rigidity or strength of the vehicle in which it is to be fitted and is unable to support its own weight and so requires mounting in a frame. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a mounting frame fora traction battery of an electric vehicle, a traction battery assembly for an electric vehicle comprising a mounting frame of the invention and a vehicle comprising a traction battery assembly of the invention, as claimed in the appended claims According to an aspect of the present invention there is provided a mounting frame for a traction battery of an electric vehicle, comprising: a plurality of peripheral frame members; and a plurality of spaced-apart elongate cell support frame members extending between opposed peripheral frame members; wherein each cell support frame member comprises a flange extending towards an adjacent cell support frame member, such that flanges of any two adjacent cell support frame members are opposing and are configured to support a non-structural cell stack comprising a plurality of battery cells, in use. The term “non-structural cell stack” is intended to mean that the cell stack does not form part of the structure of the vehicle in which it is to be fitted and / or does not contribute to the requisite determined rigidity or strength of the vehicle in which it is to be fitted and / or is unable to support its own weight and requires mounting in a frame. The flanges extending from each cell support frame member towards an adjacent cell support frame member provide surfaces on which battery cells may be mounted and supported. In addition, the elongate cell support frame members extending between opposed peripheral frame members increase the stiffness of the frame, which reduces distortion of the mounting frame during driving of a vehicle in which it is installed, thereby reducing the likelihood of damage to battery cells mounted within the frame. The elongate cell support frame members also increase the strength of the frame, which is important as it reduces the likelihood of damage to battery cells mounted within the frame during a collision of a vehicle in which the mounting frame is installed. Optionally, the flange extending from each cell support frame member is aligned with the flange extending towards it from the adjacent cell support frame member. This allows battery cells to be mounted in a precise and regular manner within the mounting frame, in order to maximise utilisation of the available volume. Optionally, at least one cell support frame member comprises first and second flanges extending respectively in opposite directions towards adjacent cell support frame members on opposite sides of the cell support frame member from which the first and second flanges extend. The provision of first and second flanges extending in opposite directions towards adjacent cell support frame members allows battery cells to be mounted and supported on both sides of a cell support frame member. Optionally, each flange comprises a planar support surface. This allows reliable and consistent engagement with a corresponding planarsurface of a battery cell and allows the battery cell to be mounted and supported along its whole length. It also facilitates securing the battery cell to the flanges. The support surface is preferably an upper surface of the flange. Optionally, the planar support surfaces of opposed flanges extending from adjacent cell support frame members are coplanar. This helps to ensure that the opposite edges of the battery cell which are supported by opposed flanges of adjacent cell support frame members are supported uniformly along their length. Optionally, the mounting frame comprises a plurality of cell support frame members having a first elongate portion and a second elongate portion aligned with, and mounted on, the first elongate portion, and wherein each of the first and second elongate portions comprises a flange extending towards the first elongate portion and the second elongate portion respectively of an adjacent cell support frame member. This allows a plurality of layers of battery cells to be mounted within the mounting frame, with a first lower layer supported on opposed flanges extending from the first elongate portions of adjacent cell support frame members and a second upper layer supported on opposed flanges extending from the second elongate portions of adjacent cell support frame members. Optionally, the flanges extending from the first and second elongate portions are aligned respectively with the flanges extending toward them from the first and second elongate portions of an adjacent cell support frame member. This allows battery cells to be mounted in a precise and regular manner within the mounting frame, in order to maximise utilisation of the available volume, which is particularly important if multiple layers of battery cells are to be mounted within the frame. Optionally, the mounting frame comprises a plurality of cell support frame members having a third elongate portion, and wherein the flange extending from each third elongate portion extends towards the third elongate portion of an adjacent cell support frame member. The flanges of the third elongate portions of the cell support frame members provide surfaces on which a lid can be mounted such that it is spaced from, and not supported by, the battery cells mounted within the frame. Optionally, the flange extending from each third elongate portion is aligned with the flange extending toward it from the third elongate portion of an adjacent cell support frame member. The upper surfaces of the flanges extending from the third elongate portions provide spaced-apart support services for a lid which are at the same level as each other, which facilitates mounting and securing of the lid onto the mounting frame. Optionally, the mounting frame comprises a plurality of cell support frame members extending between the same peripheral frame members. Typically, the peripheral frame will comprise two opposed frame members, for example lateral frame members, and it is convenient forthe cell support frame members to extend between those two opposed frame members. Optionally, the mounting frame comprises a plurality of cell support frame members extending between two substantially parallel peripheral frame members. Optionally, the flanges of the cell support frame members form part of an extruded body. Extrusion of the flanges provides a smooth surface which facilitates mounting and securing of battery cells onto the flanges. According to another aspect of the invention, a traction battery assembly for an electric vehicle, comprising a mounting frame in accordance with the invention and a non-structural cell stack comprising a plurality of battery cells, the non-structural cell stack being supported on opposed flanges of adjacent cell support frame members. Optionally, the battery cells are bonded by adhesive to the flanges on which they are supported. Mounting the battery cells onto the cell support frame members ensures that the battery cells are not loadbearing in use. That in turn allows the battery cells to be secured by adhesive to the flanges, which reduces cost and weight. According to another aspect of the invention, a vehicle comprises a traction battery assembly in accordance with the invention. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of an embodiment of mounting frame for a traction battery of an electric vehicle, with a plurality of battery cells mounted within the frame; Figure 2 shows an end view of a portion of the mounting frame of Figure 1, to a larger scale; Figure 3 shows a perspective view of a cell support frame member which forms part of the mounting frame of Figure 1; and Figure 4 shows an end view of the cell support frame member of Figure 3. DETAILED DESCRIPTION Figure 1 illustrates a mounting frame 10 for a traction battery of an electric vehicle, shown with a plurality of electric battery cells 12 mounted on the frame. The frame 10 comprises first and second straight, elongate, parallel side peripheral frame members 14,16 and front and rear peripheral frame members 18, 20 extending perpendicularly to the side frame members between the opposed front and rear ends respectively of the side frame members 14, 16. The mounting frame 10 thereby forms a continuous unbroken loop and, in use, is mounted in an electrically-powered vehicle. A plurality of identical straight, elongate cell support frame members 24 extend between, and perpendicularly to, the side peripheral frame members 14, 16 and are secured at their ends to the side peripheral frame members 14,16. As best seen in Figures 1 and 2, the cell support frame members 24 support lower and upper layers or stacks 26, 28 of electric battery cells 12. In this embodiment, the battery cells 12 are of the so-called “cell to pack” (“C2P”) design, in that the individual battery cells 12 are mounted directly within the mounting frame without first being encased with other cells in a battery module. The cell stacks are best seen in Figures 1 to 3, each elongate cell support frame member 24 comprises elongate lower, intermediate and upper portions 30, 32, 34 each of which is extruded from a lightweight metal such as aluminium and which are secured together to form the cell support frame member 24. The lower portion 30 of the cell support frame member 24 comprises an elongate planar plate 40 and a hollow elongate rectangular-section body portion 42 aligned with the longitudinal axis of the plate 40 and extending perpendicularly from the upper face of the plate 40, thereby forming flanges 44, 46 extending in opposite directions from either side of the body portion 42. The body portion 42 comprises two planar side walls 48, 50 extending perpendicularly from the plate and a planar end wall 52 extending perpendicularly to the side walls 48, 50 at their upper ends. An internal planar reinforcing web 54 also extends perpendicularly between the inner faces of the side walls 48, 50 at a location adjacent to, but spaced from, the upper ends of the side walls 48, 50. In this embodiment, the side walls 48, 50 and the end wall 52 of the lower portion 30 are also partly cut away at one end upper portion of the lower portion, as shown at 56, to allow internal battery components such as cooling conduits, busbars and the like to pass through the frame. However, the cut away portions 56 can be omitted if desired. The intermediate portion 32 comprises an elongate, hollow body 60 and two identical coplanar flanges 62, 64 extending in opposite directions from the body 60. The body 60 comprises two generally planar side walls 66, 68 from a respective one of which each of the two flanges extends perpendicularly, although the side walls are flared outwardly above and below each flange 62, 64 as shown at 70, 72, to merge smoothly with the flanges 62, 64. Lower and upper planar end walls 74, 76 extend perpendicularly to, and between the lower and upper ends respectively of, the side walls 66, 68, and the innermost edges of the two flanges 62, 64 merge into a common internal reinforcing flange 78 within the body 60. The upper portion 34 is similar in shape and dimensions to the lower portion 30 but rotated about its longitudinal axis through 180°. The upper portion therefore comprises an elongate planar plate 80 and a hollow elongate rectangular-section rectangular body portion 82 extending perpendicularly from the lower face of the plate 80, thereby forming flanges 84, 86 extending in opposite directions from either side of the body portion 82. The body portion 82 comprises two planar side walls 88, 90 extending perpendicularly from the plate and a planar end wall 92 extending perpendicularly to the side walls 88, 90 at their lower ends. An internal planar reinforcing web 94 also extends perpendicularly between the inner faces of the side walls 88, 90 at a location adjacent to, but spaced from, the lower ends of the side walls 88, 90. In use, each elongate cell support frame member 24 is assembled by aligning the longitudinal axes of the lower, intermediate and upper portions 30, 32, 34 in a plane. The outer faces of the upper and lower end walls 74, 76 of the intermediate portion are in contact with the outer face of the end wall 52 of the lower portion 30 and the outer face of the end wall 92 of the upper portion 34 respectively. The three portions are secured together by means of bolts (not shown) and adhesive. The ends of the elongate cell support frame members 24 are then secured to the side peripheral frame members 14, 16 and also bolted into position. As shown in the Figures, each cell support frame member 24 has a pair of lower flanges 44, 46, a pair of intermediate flanges 62, 64 and a pair of upper flanges 84, 86, the flanges of each pair extending laterally in opposite directions. As best seen in Figure 2, when elongate cell support frame members 24 are mounted between the side peripheral frame members 14, 16, each cell support frame member 24 has lower, intermediate and upper flanges aligned with, and extending towards, corresponding lower, intermediate and upper flanges of an adjacent cell support frame member 24. The upper faces of the lower flanges 44, 46 provide support surfaces on which a lower layer or row 26 of electric battery cells 12 can be supported and which, in use, are secured to the upper faces of the flanges 44, 46 by means of adhesive. Similarly, the upper faces of the intermediate flanges 62, 64 provide support surfaces on which an upper layer or row 28 of electric battery cells 12 can be supported and which, in use, are also secured to the upper faces of the flanges 62, 64 by means of adhesive. The elongate cell support frame members 24 extending between the opposed peripheral frame members 14, 16 increase the stiffness of the mounting frame 10, which reduces distortion of the mounting frame during driving of a vehicle in which it is installed, thereby reducing the likelihood of damage to the battery cells 12 mounted within the frame. The elongate cell support frame members 24 also increase the strength of the frame 10, which is important as it reduces the likelihood of damage to the battery cells 12 mounted within the frame during a collision of a vehicle in which the mounting frame is installed. In this particular embodiment, the upper flanges 84, 86 do not support the weight of any electric battery cells 12, but instead provide protection for the upper layer 28 of cells 12 also be used to engage with other components of the vehicle to prevent those other components from damaging the battery cells 12 mounted within the frame 10. It will be appreciated that the mounting frame may be configured to allow further layers of battery cells 12 to be mounted. However, the upper flanges 84, 86, as well as the lower faces of the flanges 62, 64, serve to locate and restrain (as may be necessary) the battery cells 12 in their respective layers. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A mounting frame for a traction battery of an electric vehicle, comprising: a plurality of peripheral frame members; anda plurality of spaced-apart elongate cell support frame members extending between opposed peripheral frame members;wherein each cell support frame member comprises a flange extending towards an adjacent cell support frame member, such that flanges of any two adjacent cell support frame members are opposing and are configured to support a non-structural cell stack, comprising a plurality of battery cells, in use.

2. A mounting frame as claimed in claim 1, wherein the flange extending from each cell support frame member is aligned with the flange extending towards it from the adjacent cell support frame member.3, A mounting frame as claimed in claim 1 or claim 2, wherein at least one cell support frame member comprises first and second flanges extending respectively in opposite directions towards adjacent cell support frame members on opposite sides of the cell support frame member from which the first and second flanges extend.

4. A mounting frame as claimed in any of claims 1 to 3, wherein each flange comprises a planar support surface.

5. A mounting frame as claimed in claim 5, wherein the planar support surfaces of opposed flanges extending from adjacent cell support frame members are coplanar.

6. A mounting frame as claimed in any of claims 1 to 5, comprising a plurality of cell support frame members having a first elongate portion and a second elongate portion aligned with, and mounted on, the first elongate portion, and wherein each of the first and second elongate portions comprises a flange extending towards the first elongate portion and the second elongate portion respectively of an adjacent cell support frame member.

7. A mounting frame as claimed in claim 6, wherein the flanges extending from the first and second elongate portions are aligned respectively with the flanges extending toward them from the first and second elongate portions of an adjacent cell support frame member.

8. A mounting frame as claimed in claim 6 or claim 7, comprising a plurality of cell support frame members having a third elongate portion, and wherein a flange extends from each third elongate portion towards the third elongate portion of an adjacent cell support frame member.

9. A mounting frame as claimed in claim 8, wherein the flange extending from each third elongate portion is aligned with the flange extending toward it from the third elongate portion of an adjacent cell support frame member.

10. A mounting frame as claimed in any of claims 1 to 9, comprising a plurality of cell support frame members extending between the same peripheral frame members.5 11. A mounting frame as claimed in claim 10, comprising a plurality of cell support frame membersextending between two substantially parallel peripheral frame members.

12. A mounting frame as claimed in any of claims 1 to 10, wherein the flanges of the cell support frame members form part of an extruded body.1013. A traction battery assembly for an electric vehicle, comprising a mounting frame as claimed in any of claims 1 to 12 and a non-structural cell stack comprising a plurality of battery cells, the non-structural cell stack being supported on opposed flanges of adjacent cell support frame members.15 14. A traction battery assembly as claimed in claim 13, wherein the battery cells are bonded by adhesiveto the flanges on which they are supported.

15. A vehicle comprising a traction battery assembly as claimed in claim 13 or claim 14.

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