Ring for cylindrical electrochemical cell of rechargeable battery

Abstract

The invention relates to a ring (100) for a cylindrical electrochemical cell (10) of a rechargeable battery, comprising an annular body (110) adapted to be engaged on said electrochemical cell. According to the invention, the ring comprises at least one fin (120) which is made at least partially of an electrically conductive material and which is movable on the annular body between a retracted position and an extended position in which it protrudes more from the annular body than in the retracted position. Figure for the abstract: Fig. 3

Description

Title of the invention: Ring for cylindrical electrochemical cell of rechargeable battery Technical field of the invention

[0001] The present invention relates generally to the technical field of accumulator batteries, and more particularly to the assembly and connection of electrochemical cells of cylindrical shape within an accumulator battery.

[0002] It relates more particularly to a ring for such a cylindrical electrochemical cell, comprising an annular body adapted to be engaged on said electrochemical cell.

[0003] It also relates to a battery of accumulators comprising a plurality of cylindrical electrochemical cells.

[0004] It also relates to a motor vehicle comprising an electric traction machine and such a battery.

[0005] It also relates to a method of extracting a cylindrical electrochemical cell of a battery from its support. State of the art

[0006] An electric or hybrid motor vehicle ordinarily includes an electric motor and a battery of accumulators which is specially designed to supply the electric motor with current in order to propel the vehicle.

[0007] Such a battery comprises a large number of electrochemical cells delivering a low voltage (a few volts), connected in series with each other so that the overall voltage across the battery terminals is high enough to propel the vehicle. The voltage across the terminals of such a battery can, for example, be on the order of 400 V.

[0008] Currently, two main types of battery architectures are known.

[0009] The first type is that of so-called modular batteries. In such a battery, the electrochemical cells are distributed among several identical modules housed in a main compartment. Each of these modules includes a housing for the electrochemical cells.

[0010] The second type is that of moduleless batteries, better known by the English term "cell-to-pack". The electrochemical cells of such a battery are generally installed directly in the main compartment and connected to each other.

[0011] Different kinds of electrochemical cells are used in these two types of storage batteries, in order to meet the requirements of a wide variety of applications. The most commonly used electrochemical cells in vehicles are cylindrical cells, prismatic cells and pouch cells.

[0012] Cylindrical cells offer certain advantages over other cell shapes, such as adaptability. Indeed, due to their small size (compared to prismatic and pouch cells), it is possible to imagine a large number of module shapes. However, these cells also have disadvantages, such as the difficulty of holding them together and connecting them to one another.

[0013] Document US20200194742 then proposes to use grooved and insulating caps to hold the electrochemical cells together.

[0014] Generally, to ensure the electrical connection, electrical conductors (commonly called busbars) are soldered directly onto the cells.

[0015] Such an assembly proves robust, but has the major drawback of not being easily disassembled, particularly when one of the cells proves defective and needs to be replaced. The presence of welds complicates this type of intervention. Presentation of the invention

[0016] In order to remedy the aforementioned drawbacks of the prior art, the present invention proposes to equip the cylindrical cells with devices facilitating their retention and ensuring their electrical connection, without welding.

[0017] More particularly, the invention proposes a ring as defined in the introduction, comprising at least one fin which is made at least partly of an electrically conductive material and which is movable on the annular body of the ring between a retracted position and a deployed position in which it protrudes more outside the annular body than in the retracted position.

[0018] Thus, thanks to the invention, the ring makes it possible to lock the electrochemical cell in its support. To this end, each fin is designed to deploy in a recess provided for this purpose in the support.

[0019] The fin is also designed to conduct current, so that it is no longer necessary to solder the battery cells together, as will be described in detail later.

[0020] Other advantageous and non-limiting features of the ring according to the invention, taken individually or in all technically possible combinations, are as follows: - at least three fins are planned; - the fins are regularly distributed all around the annular body; - each fin is mounted on the annular body so that it can pivot, and elastic return means are provided for each fin in the deployed position; - each fin is formed with the annular body and is shaped to be automatically recalled to the deployed position; - in retracted position, each fin presents an external face which extends in line with or recesses inwards from an external face of the annular body.

[0021] The invention also proposes a battery of accumulators comprising a plurality of cylindrical electrochemical cells, and a support which delimits at least one hollow housing along a first axis, said housing having at least one recess along a second axis inclined with respect to the first axis, each electrochemical cell carrying a ring as above, the body of which is engaged in said housing along the first axis and said at least one fin of which is engaged in said recess.

[0022] Preferably, the support has, at the bottom of the housing, an electrical connection element for a terminal of the electrochemical cell.

[0023] The invention also proposes a motor vehicle comprising an electric traction machine and a battery of accumulators as above, adapted to supply current to the electric traction machine.

[0024] The invention finally proposes a method for extracting a cylindrical electrochemical cell from a battery of accumulators as mentioned above, in which it is provided to rotate said electrochemical cell around the first axis and then slide it out of the housing along the first axis.

[0025] Of course, the various features, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0026] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0027] On the attached drawings:

[0028] [Fig. 1] schematically represents a bare electrochemical cell and an electrochemical cell equipped with a ring according to the invention;

[0029] [Fig.2] schematically represents two top views of the ring of [Fig.1], on which a fin is shown in the deployed position (on the left) and in the retracted position (on the right);

[0030] [Fig.3] schematically represents three views respectively in perspective, of above and side of the electrochemical cell equipped with the [Fig.l] engaged in a support;

[0031] [Fig.4] is a schematic perspective view of a cell mounting tool electrochemical unit fitted in the support of [Fig.3].

[0032] In the left view of [Fig.1], an electrochemical cell 10 of a battery of accumulators which will hereafter be called a traction battery is shown.

[0033] Here, and preferably, this traction battery is intended to be used within a motor vehicle.

[0034] This motor vehicle could be of any type (truck, bus, airplane, boat). Preferably, it will be a car which conventionally comprises a chassis, wheels of which at least two are driven, and a powertrain adapted to turn the driven wheels.

[0035] The powertrain is preferably purely electric, but alternatively it could be hybrid. In all cases, it comprises at least one electric machine (hereinafter referred to as a motor) supplied with current by the traction battery.

[0036] The traction battery comprises an outer casing which houses a plurality of electrochemical cells 10 of the type illustrated in [Fig.1].

[0037] This traction battery could be of any type.

[0038] Thus, it can be modular, in which case the electrochemical cells 10 will be distributed into several identical modules each comprising a cassette which is housed in the outer casing and which itself houses cells.

[0039] Alternatively, it could be module-free (“cell-to-pack”), in which case the electrochemical cells will be installed directly in the outer casing.

[0040] Preferably, all the electrochemical cells 10 of the accumulator battery are identical. Only one of them will be described below.

[0041] It could typically be a lithium-ion type cell, but other variants would be conceivable.

[0042] This electrochemical cell 10, for example, has a voltage across its terminals of the order of 3 to 5 V. In the traction battery, the electrochemical cells are then connected to each other to reach the voltage level required by the application (in series or in series and parallel).

[0043] Typically, there will be around one hundred of these cells, so that the electric motor can develop sufficient torque and power to propel the vehicle for a desired duration. Thus, the voltage at the external terminals of the traction battery will be approximately 400V. In practice, 96 cells are planned here. Of course, the number of cells could be greater (around 200, for example) or less.

[0044] Here, each electrochemical cell 10 has a cylindrical shape of revolution around a first axis Al.

[0045] Such a cell is well known to a person skilled in the art and will therefore not be described in detail.

[0046] It can only be specified that it has a cylindrical lateral wall 11 of revolution, closed on one side by a flat base and on the other by a flat top surmounted by a pin 12.

[0047] Here, the side wall 11 forms one electrical terminal of this electrochemical cell 10 (the negative terminal), while the pin 12 forms the other electrical terminal of this electrochemical cell 10 (the positive terminal). These two terminals are therefore electrically connected to the electrodes of this cell. The flat top portion is located around the pin 12 and is thus electrically insulating.

[0048] In the following description, the upper term will refer to the side towards which the flat top of the electrochemical cell 10 is turned, while the lower term will refer to the opposite side.

[0049] The term interior (or internal) will be used to designate the side of an element turned towards the first axis Al while the term exterior (or external) will be used to designate the opposite side.

[0050] According to a particularly advantageous feature of the invention, the electrochemical cell 10 is equipped with a ring 100 allowing not only for fixing it within the external housing of the traction battery, but also for connecting it to the rest of the traction battery.

[0051] As further shown in [Fig.1], this ring 100 has an annular body 110 for its attachment to the electrochemical cell 10 and at least one fin 120 to ensure the locking of this cell and its electrical connection in the traction battery.

[0052] The annular body 110 could appear in various forms.

[0053] It is presented here in the form of a tube of revolution around the first axis Al (when it is engaged on the electrochemical cell 10). It has an inner diameter adjusted to the outer diameter of the electrochemical cell 10, so that it is press-fitted onto it.

[0054] Preferably, the annular body 110 may be provided to have, on its upper end, an inner rim forming a stop. Thus, when the ring 100 is mounted on the electrochemical cell 10, this stop will bear against the top of the electrochemical cell 10, thereby ensuring its correct positioning on this electrochemical cell 10.

[0055] Alternatively, if the electrochemical cell 10 had an external thread, the annular body 110 could have a corresponding thread so as to be able to be screwed onto this electrochemical cell 10.

[0056] As a further alternative, the annular body 110 could be glued onto the electrochemical cell 10.

[0057] The annular body 110 has a height (measured along the first axis Al) which is less than or equal to that of the electrochemical cell 10. Its height is preferably less than half that of the electrochemical cell 10.

[0058] The annular body 110 is preferably made in one piece from an electrically conductive material. Alternatively, it could be made from an electrically insulating material, in which case it must incorporate an electrical conductor enabling the fin 120 to be electrically connected to the side wall 11 of the electrochemical cell 10.

[0059] In figures 1 and 2, the ring has a single fin 120.

[0060] However, preferably, it will include more of them.

[0061] It could, for example, include three of them.

[0062] In the example illustrated in [Fig.3], it comprises eight.

[0063] These fins 120 are preferably regularly distributed all around the first axis AL

[0064] At least one of the fins 120 is preferably made in one piece from an electrically conductive material. Alternatively, it could be made from an electrically insulating material, in which case it must incorporate an electrical conductor.

[0065] Here, the fins 120 and the annular body 110 are all made of the same electrically conductive material, typically a metallic material, for example aluminium or copper.

[0066] Each fin 120 is movable on the annular body 110 between a retracted position and a deployed position in which it protrudes more from the annular body 110 than in the retracted position. In other words, the distance between the first axis Al and the point of the fin 120 furthest from this axis is greater in the deployed position than in the retracted position.

[0067] Preferably, each fin 120 is articulated or pseudo-articulated on the annular body, so as to be able to pivot around a pivot axis A2 ([Fig.1]).

[0068] Preferably, the pivot axes A2 are parallel to the first axis AL

[0069] In the embodiment illustrated in [Fig.2], this articulation is achieved using a pin 121 which creates a hinge between the corresponding fin 120 and the annular body 110.

[0070] In this mode, an elastic return means for this fin 120 in the deployed position is provided. This return means can typically be in the form of a torsion spring 122 threaded around the pin 121, one end of which bears against the annular body 110 while the other bears against the fin 120.

[0071] In a second embodiment not illustrated in the figures, each fin could be formed with the annular body. Thus, the annular body and the fins could be molded as a single piece. The fins would then be molded in the deployed position so as to be naturally returned to this position.

[0072] In a third embodiment not illustrated in the figures, the fins could be cut out of the annular body and folded outwards. Here again, at rest (i.e., when no force is exerted on the fins), the fins would naturally return to the deployed position.

[0073] In both of these embodiments, it can be said that the fins are pseudo-articulated on the annular body.

[0074] The fins 120 could be positioned at different heights relative to the annular body 110.

[0075] In the embodiment illustrated in the figures, they extend above this annular body 110.

[0076] Alternatively, they could extend to the height of the annular body 110, or below it.

[0077] Preferably, in the retracted position, each fin 120 will extend inward or flush with the outer face of the annular body 110. Thus, in the retracted position, the fins 120 will not obstruct the mounting or dismounting of the electrochemical cell 10 in its support.

[0078] In the variant in which the fins extend to the height of the annular body, it may be provided that the fins are housed in hollow cavities in the external face of the annular body 110 so that in the retracted position, the external faces of the fins extend in line with the external face of the annular body 110.

[0079] The electrochemical cells 10 are retained in the traction battery by a support 200.

[0080] In the modular configuration, this support could be formed by the module cassette. In the so-called "cell-to-pack" configuration, the support could be formed by the outer casing of the traction battery.

[0081] However, preferably, this support 200 will form a separate part from the cassette or outer casing, brought into this cassette or outer casing and fixed to it.

[0082] As shown in [Fig. 3], this support 200 is here in the form of a thick plate, the inner face of which has as many recesses 210 as there are a of electrochemical cells 10 to block. For clarity, in the following, we will only consider one of these recesses 210.

[0083] Here, each recess 210 thus forms a housing 210 fitted to the shape of the annular body 110 of the ring 100 of the corresponding electrochemical cell 10. Therefore, each housing 210 preferably has a cylindrical shape of revolution about the first axis Al (when the cell is attached to it), with a diameter fitted to the outer diameter of the annular body 110. The fit will be designed to allow the ring 100 to be mounted in the housing 210 tightly but not by force.

[0084] In other words, this adjustment will be such that the electrochemical cell 10 will be blocked in the support 200 except in rotation around the first axis Al and in translation along this first axis.

[0085] It should be noted here that when they are in the retracted position, the fins 120 do not hinder the placement of the electrochemical cell 10 equipped with its ring 100 in its housing 210.

[0086] In order that, once the electrochemical cell 10 is installed in its housing 210, the fins 120 can deploy and block the translational movement of this cell in the support 200, each housing 210 has, in its lateral wall, at least one recess 220 in which at least one of the fins can deploy. These recesses 220 are cut radially into the housing 210. They can therefore be said to extend along second axes inclined with respect to the first axis A1.

[0087] Preferably, the housing 210 will be provided with as many recesses 220 as the ring 100 has fins 120, so that each fin 120 can deploy in an individual recess. Thus, each recess 220 will be located at a distance from the two adjacent recesses 220 surrounding it. In other words, two neighboring recesses 220 will define between themselves a portion of the support 200 adapted to bear against the ring 100, which will be referred to hereafter as the relief 230.

[0088] These recesses 220 all have a flat lower face located in a plane orthogonal to the first axis Al. Correspondingly, each fin 120 has a straight lower edge located in a plane orthogonal to the first axis Al.

[0089] Thus, once deployed in its housing, the fin 120 prevents the electrochemical cell 10 from moving back down and coming out of its housing 210.

[0090] To ensure the electrical connection of the electrochemical cell 10 to the other cells, the support 200 includes separate electrical connection means for the two terminals of this cell.

[0091] These connection means first of all comprise, at the bottom of the housing 210, an electrical connection element 212 for the pin 12 of the electrochemical cell 10. This electrical connection element 212 is, for example, in the form of a fixed protruding lug from the bottom of housing 210. This lug is then connected to an electrical conductor insulated from the support.

[0092] Alternatively, the electrical connection element 212 could be in the form of a spring, to facilitate the engagement of the electrochemical cell 10 in this housing 210.

[0093] Similarly, electrical connection elements for the fins 120 of the ring 100 can be provided at the bottom of each recess 220 or part of them, which are electrically connected to the other terminal of the electrochemical cell 10 since they are made of an electrically conductive material.

[0094] However, preferably, the entire support 200 will itself be made of an electrically conductive material, which will ensure the electrical connection of the fins 120 (and therefore the electrical connection of the negative terminal of the cell). It will, however, be electrically isolated from the electrical connection element 212.

[0095] We can now describe how an electrochemical cell 10 is installed in the support 200.

[0096] In a first step, this cell is first fitted with the ring 100.

[0097] Then, the fins 120 are folded into the retracted position.

[0098] This operation can be carried out manually, in particular if the ring 100 is equipped with a limited number of fins 120.

[0099] Alternatively, especially if the ring 100 is equipped with a large number of fins 120 (as illustrated in [Fig.3]), it is possible to use a tool such as the one shown in [Fig.4].

[0100] This tool has a circular base 301 bordered on one side by a tubular wall 302 of revolution, with an inner diameter slightly greater than the outer diameter of the ring 100. The free end edge of this tubular wall 302 is serrated, so as to present teeth 311. Preferably, as many teeth are provided as the ring 100 has fins 120.

[0101] The tubular wall 302 has a height substantially equal to that of the electrochemical cell 10. Its teeth 311 are thus provided to fit between the fins 120 when the tool 300 is brought back onto the electrochemical cell 10, from the bottom of the latter.

[0102] Then, by rotating the tool 300 relative to the electrochemical cell 10, the teeth 311 can press against the fins 120 and force them to fold into the retracted position.

[0103] When this is the case, the electrochemical cell 10 can be brought back under its housing 210. The diameter of the tool 300 does not allow it to engage in the housing 210. So, the idea is to place it in the axis of the housing 210, then to push the electrochemical cell 10 into the housing 210, out of the tool 300. For this purpose, the bottom 301 of the tool 300 is pierced with an opening 320 here circular, which allows a rod to be inserted to push the electrochemical cell 10 out of the tool 300.

[0104] It may then be necessary to rotate the electrochemical cell 10 in its housing 210 in a first direction of rotation RI ([Fig. 3]), so that the fins 120 are aligned with their recesses 220 and can naturally extend into them. The shape of the recesses 220 is then designed so that once the fins 120 have extended, the electrochemical cell 10 can no longer rotate in its housing 210 in the first direction of rotation RI.

[0105] In this position, the electrical connection of this electrochemical cell 10 to the other cells of the traction battery is automatically made.

[0106] At this stage, we can now describe how an electrochemical cell 10 can be extracted from its support 200.

[0107] In a first step, the traction battery is disconnected from the electrical network of the motor vehicle, then the external case of the traction battery is opened so as to be able to access this electrochemical cell 10 from below.

[0108] Then, the operator can grasp this cell from below and rotate it around the first axis Al in a second direction of rotation opposite to the first direction of rotation RI.

[0109] The shape of the recesses 220 and the reliefs 230 is indeed designed so that this movement forces the fins 120 to fold back into the retracted position.

[0110] When this is the case, the operator can apply a pulling force on the cell, downwards, along the first axis Al, so as to remove it from its housing 210.

[0111] Thus, in two movements, the operator can disconnect the electrochemical cell 10 from the rest of the traction battery and remove it from the external case.

[0112] This cell can then be simply replaced by another cell of the same type.

Claims

Demands

1. Ring (100) for cylindrical electrochemical cell (10) of accumulator battery, comprising an annular body (110) adapted to be engaged on said electrochemical cell (10), characterized in that it comprises at least one fin (120) which is made at least partly of an electrically conductive material and which is movable on the annular body (110) between a retracted position and a deployed position in which it protrudes more outside the annular body (110) than in the retracted position.

2. Ring (100) according to claim 1, wherein at least three fins (120) are provided.

3. Ring (100) according to claim 2, in which the fins (120) are regularly distributed all around the annular body (110).

4. Ring (100) according to any one of claims 1 to 3, wherein each fin (120) is mounted on the annular body (110) so as to be able to pivot, and wherein elastic return means for each fin (120) are provided in the deployed position.

5. Ring (100) according to any one of claims 1 to 3, wherein each fin (120) is formed with the annular body (110) and is shaped to be automatically recalled to the deployed position.

6. Ring (100) according to any one of claims 1 to 5, wherein, in the retracted position, each fin has an external face which extends in line with or recesses inwards from an external face of the annular body.

7. Accumulator battery comprising a plurality of cylindrical electrochemical cells (10), characterized in that it comprises a support (200) which delimits at least one recessed housing (210) along a first axis (A1), said housing (210) having at least one indentation (220) along a second axis inclined with respect to the first axis, and in that each electrochemical cell (10) carries a ring (100) according to any one of claims 1 to 6, the body (110) of which is engaged in said housing (210) along the first axis (A1) and said at least one fin (120) of which is engaged in said indentation (220).

8. Accumulator battery according to claim 7, wherein the support (200) has, at the bottom of the housing (210), an electrical connection element (212) for a terminal (12) of the electrochemical cell (10).

9. Motor vehicle comprising an electric traction machine, characterized in that it comprises a battery of accumulators conforming to one of claims 7 and 8, adapted to supply current to the electric traction machine.

10. Method of extracting a cylindrical electrochemical cell (10) from a support (200) of a battery of accumulators according to one of claims 7 and 8, wherein it is provided to rotate said electrochemical cell (10) around the first axis (Al) and then to slide it out of the housing (210) along the first axis (Al).

Images