This invention relates to a cell tray for a battery and, in particular, a cell tray which supports and retains a plurality of battery cells.
Electric powered or hybrid vehicles are well known and are becoming more and more prevalent as the desire to reduce carbon emissions increases. In such vehicles, the power that can be provided by, and the weight of, the battery is vital in determining the performance of the vehicle. The power to weight ratio of the battery is therefore something that vehicle designers are trying to optimise. This can clearly be done either by increasing the power generated for a given weight or by reducing the weight for a given power output, or most likely a combination of the two.
The batteries in electric or hybrid vehicles are typically made up of a plurality of individual battery cells connected together in such a way to allow large amounts of power to be provided to drive the wheels or power other systems in the vehicle. These cells are typically provided in the form of one or more battery modules which can be electrically connected.
Battery cells have optimum operating conditions and, in particular, operating temperatures. If the battery cells are outside of these optimum conditions, then the performance of the cells can deteriorate and the power the cells can provide is reduced. Alternatively or additionally, overheating can affect the operating life and/or general reliability of the battery cells, which is also undesirable.
It is known to provide cell trays having a plurality of holes or recesses for holding battery cells. Such cell trays allow coolant fluid to circulate around parts of the battery cells, thereby providing a cooling effect to the cells as heat is transferred from the cells to the coolant. It is known to use a pair of cell trays, one supporting each end of the battery cells, with the coolant fluid being permitted to flow over the central portion of each cell, but having the cell terminals of the cells, typically located at each end of the cell, covered. It is also known to mount cells in a support structure such that the outer cylindrical surface of the cell is substantially fully enclosed by the cell holder.
According to the present invention there is provided a battery cell tray comprising a main body having a plurality of holes extending therethrough from a first face to a second face, a plurality of battery cells, each cell retained in a respective hole of the main body, wherein each cell protrudes out of the main body on both the first and the second faces.
Such a cell tray is beneficial as it permits a single cell tray to be used rather than multiple trays, one at each end of the cells, thereby minimising material usage and therefore reducing the weight of the battery module. It also permits coolant fluid to flow around a significant portion of each cell thereby maximising the cooling effect provided and allowing the battery cells to operate within the optimum temperature range.
The cells may supported by the cell tray substantially at the mid point of the cell. Each cell may have a pair of terminals, one at each end, and wherein the terminals of each cell are exposed. The cells are preferably configured in a staggered pattern across the longitudinal plane of the cell tray. Some cells may have a reversed orientation with respect to other cells.
At least one face of the main body may have a recessed portion configured to receive a resin.
The invention further provides a battery cell tray comprising a main body having a plurality of holes extending therethrough from a first face to a second face, each hole being configured to retain a battery cell, wherein at least one of the faces of the main body has a recessed portion configured to receive a resin for retaining the battery cells in the holes.
The provision of the recess portion for receiving a resin is beneficial as it enables the cells to be fixedly help in place using a simple and easy to apply resin and which, by virtue of being within a recess, does not increase to volume of the cell try. This allows the greatest amount of each cell to be exposed to coolant.
The cell tray may further comprise a plurality of battery cells. The recessed portion may extend around at least part of the end of a cell hole. Multiple recessed portions may be provided in a face, each recessed portion extending around at least part of the end of a respective cell hole.
Each cell hole may have at least one recessed portion extending around at least part of an end of the hole. The recessed portion may extend around the ends of a plurality of the cell holes. Each recessed portion may contain a resin for retaining the cells in the holes. At least one recessed portion may be provided on each face.
There may be a step change between a cell hole and a respective recessed portion. There may be a graduated change between a cell hole and a respective recessed portion.
The cells may be supported by the cell tray substantially at the mid point of the cell. Each cell may have a pair of terminals, one at each end, and wherein the terminals of each cell are exposed. The cells are preferably configured in a staggered pattern. Some cells may have a reversed orientation with respect to other cells. It is preferable that the arrangement of the reversed cells assists in allow the desired cell configuration to be achieved. The preferred cell configuration comprises 48 cells, which are arranged in 3 parallel groups of 16 cells in series. Alternative configurations may be possible, such as 2 parallel groups of 24 cells in series, or 6 parallel groups of 8 cells in series. Different total numbers of cells could be used with a suitably larger or smaller cell tray. The pattern of reversal is typically based upon trying to create the desired cell configuration in the simplest manner. This might be to reduce the length of the connections between adjacent cells in a series or it might be to keep cells of different groups either together or apart.
The cell tray may further comprise one or more flow openings within the cell tray to permit coolant flow to pass from one side of the cell tray to the other. The flow opening or openings may be larger towards the most distal part of the housing. The flow opening(s) may be provided at one end of the cell tray.
The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art.
The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.
Battery Overview
The battery may be installed in a vehicle.
The battery 1 may further comprise a battery control unit 12 which protrudes from the row of battery modules. The battery control unit 12 may be electrically connected to one or more module control units 12a. Each battery module 2 may comprise an attached module control unit 12a. The battery control unit 12 may control each battery module control unit 12a. Each battery module control unit 12a may control the activity of the respective attached battery module. Each battery module control unit 12a may receive information concerning the operation of the respective attached battery module. The battery module control units 12a may process that information and feed that information to battery control unit 12.
The battery modules and battery control unit 12 may be enclosed by the battery floor 1a and a battery housing 1b.
Cell Tray
An exemplary cell tray 4 is shown in
The cell tray may further comprise a fixing hole 5 configured to receive a fixing element (not shown) for securing the cell tray 4, and hence the battery module 2, to the battery floor (not shown).
Resin may be poured into a recessed side of the cell tray. The resin may harden around cells placed in the cell tray so as to secure the cells in the cell tray. Alternatively, each cell 7 may be held in a cell hole 6 by an interference fit between the cell tray 4 surrounding the cell hole and the cell inserted into the respective cell hole.
Each cell hole may extend through the cell tray in a direction perpendicular to the longitudinal axis of the cell tray. In the example cell tray depicted in
The length of each cell may be greater than the length of each cell hole. Each cell 7 comprises a positive terminal and negative terminal. When a cell 7 is inserted into a cell hole 6, a length of the cell 7 comprising the positive terminal of the cell may protrude from the cell hole on one side of the cell tray 4 whilst a length of the cell 7 comprising the negative terminal protrudes from the cell hole on the other side of the cell tray. The portion of the cell 7 comprising the positive terminal and the portion of the cell 7 comprising the negative terminal may protrude from opposite sides of the cell tray. The protruding length of the portion of the cell comprising the cell's positive terminal and the protruding length of the portion of the cell comprising the cell's negative terminal may be equal.
The battery module 2 shown in
Cell to Cell Busbars and Flexible Printed Circuit Board
As above, the cell tray 4 (not shown in
Cells 7 may be arranged in the cell tray 4 so that positive and negative cell terminals protrude from opposite sides of the cell tray. In this way, a current flow path may be created through cells and busbars. For example, the current flow path may “snake” through the battery module. The current flow path may repeatedly intersect the cell tray. The current flow path may repeatedly intersect the longitudinal axis of the battery module. At least some of the cells may be connected in parallel by the busbars 10, meaning that the current flow path passes through multiple cells as the current flow path intersects the cell tray.
Module terminals 13 are shown in
The busbars 10 may be integrated with a flexible printed circuit board (not shown in
The busbars 10 shown in
The flexible printed circuit board 11 shown in
Each sense wire may be capable of communicating voltage measurements to the battery control unit. The module control unit 12a may be capable of communicating voltage measurements to the battery control unit. The battery control unit 12, also shown in
The sense wires of the flexible printed circuit board 11 may be attached to one or more temperature sensors. A temperature sensor may be capable of determining the temperature of a part of the battery module. Each sense wire may be capable of communicating temperature measurements from a temperature sensor to the module control unit. The module control unit may be capable of adapting the activity of the battery module in response to the temperature measurements provided by the sense wire. Each sense wire may be capable of communicating temperature measurements to the battery control unit. The module control unit may be capable of communicating temperature measurements to the battery control unit. The battery control unit may be capable of adapting the activity of the battery module in response to the temperature measurements. The battery control unit may be capable of adapting the activity of the battery in response to the temperature measurements.
The sense wires may be attached to other types of sensors, for example current sensors, and/or fluid flow sensors.
Module Cooling
It is known to supply coolant to regulate the temperature of batteries. In typical batteries, the coolant is confined within coolant jackets or pipes. In such batteries, cells are cooled in areas of the cell which make contact with the jacket or pipe containing the coolant. This is a slow and inefficient cooling method.
In other typical batteries, coolant is not confined by coolant jackets or pipes, but makes direct contact only with the body/centre portion of each cell. In such batteries, the cell terminals are protected so that coolant does not make contact with the cell terminals. Such contact is avoided as it would typically lead to electrical shorting. This is also an inefficient method because the cell terminals, being electrically connected, are often the hottest parts of the cell and yet they are not directly cooled by the coolant.
By contrast, in the battery module described herein, coolant supplied to the battery module 2 makes direct contact with cell terminals, flexible printed circuit board 11, busbars 10, and cell body. The entirety of the cell and connected conducting parts are bathed in coolant. The coolant used is a dielectric oil. Dielectric oils have insulating properties. Cells drenched in dielectric oil are insulated from one another preventing short circuiting between cells. This is an efficient method of regulating cell temperature. Such efficient cooling enables the cells to operate at a higher power and for longer. This means that fewer and/or smaller cells are required to generate the same power as batteries utilising the previously mentioned cooling methods.
Both coolant conduit portions may extend along the battery module in a direction orthogonal to the longitudinal axis of the battery module. Both coolant conduit portions may extend along the battery module in a direction orthogonal to the direction in which the fixing hole 5 extends through the cell tray 4. Both coolant conduit portions may extend along the battery module in a direction parallel to the direction in which the cell holes 6 extend through the cell tray 4.
As shown in
As shown in
As shown in
Inlet 16 and outlet 17 may be configured to allow coolant to enter and leave the battery module 2. Inlet 16 and outlet 17 may further act as passages through which the flexible printed circuit boards 11 pass between the interior and exterior of the battery module, as shown in
The method of direct cell cooling described herein also has further advantages in the case that excessive pressure builds up inside a cell. Each cell may comprise a cell vent port. In the case that excessive pressure builds up inside the cell, the cell vent port may be activated, allowing fluids within the cell to escape the cell. The cell vent port may be configured to expel cell fluids in the event that pressure within the cell exceeds a threshold. Upon leaving the cell, the fluids are quenched by the surrounding coolant.
Cell Tray—Further Details
With further reference to
The tray 4 has a first face 30 and second face 31. The first face 30 is provided with a recess 32. The recess is bounded by a wall 33, such that the ends of cell holes 6 on the first face are closer to a centre line of the tray than the wall 33. When battery cells are located in respective cell holes, resin can be inserted into the recess to secure the cells within the holes 6. Although not shown, the end of each cell hole may include, either as well as or instead of the recess 32, an individual cell recess into which resin can be inserted. The individual cell recess may be a stepped portion or may have a gradual change in shape.
Whilst the figures show a single recess 32 only on the first side 30 of the tray, a similar recess could be provided on the second side 31 instead of or as well as on the first side. Alternatively, one or both faces may have a plurality of recesses, each recess incorporating any number of cell holes. Alternatively, as shown in
The tray wall 33 includes arcuate recesses 34 which match to respective cell holes. Thus, whilst many of the battery cells will have resin around their entire circumference, some cells, typically those on the edges of the array of cells, will have resin only around a part of the circumference.
The tray 4 also comprises coolant flow holes 35 to 40. These coolant flow holes extend through the cell tray from one side to the other and are located at the opposite end of the cell tray to the inlet and outlet coolant flow. The coolant flow holes permit coolant to pass from one side to the other of the tray. The coolant flow holes are not intended to have a cell placed therein and are typically sized and/or shaped such that they are different from the cell holes 6, such that cell cannot fit therein. In this way, inlet coolant passes along one side of the tray, through the coolant flow holes, and outlet coolant then flows along the other side of the tray in substantially the opposite direction to the inlet coolant. It may be possible to replace the plurality of openings with a single opening which extends over a significant portion, at least 50% and preferably 75% or more, of the height of the cell tray, and in which the cross section of the opening increases in size towards the bottom of the opening.
As can be best seen in
The coolant flow holes 35 to 39 are therefore substantially triangular in shape, albeit with two arcuate sides. This shape is beneficial as it maximises the size of the flow holes for the particular configuration of the battery cells. Other shapes of flow holes could be used depending upon the cell holes configuration. For example, a circular shape hole is relatively easy to form, but may not be the most space efficient within the form of the cell tray. The coolant flow holes are larger at the bottom (in
Sections 35c to 40c illustrate the flow through openings 35 to 40 within the distal end of the cell tray 4, the openings permitting the coolant flow to pass from one side to the other of the cell tray as shown in
The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.
Number | Date | Country | Kind |
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1815185.2 | Sep 2018 | GB | national |
Filing Document | Filing Date | Country | Kind |
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PCT/GB2019/052607 | 9/17/2019 | WO | 00 |