GB2594517A

GB2594517A - Carrier and assembly for testing cylindrical cells

Info

Publication number: GB2594517A
Application number: GB2006461.4A
Authority: GB
Inventors: Crawford Ross
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2020-05-01
Filing date: 2020-05-01
Publication date: 2021-11-03
Anticipated expiration: 2040-05-01
Also published as: GB2594517B; GB202006461D0

Abstract

A carrier (200) suitable for securing a cylindrical cell (100) having a first end surface (figure 1a, 104), a second end surface (figure 1d, 105) and a cylindrical surface (figure 1a, 102) located between the first and second end surfaces, the cell comprises a first terminal (figure 1a, 101) defined by the first end surface and a second terminal (figure 1a, 103) defined by the second end surface and the cylindrical surface. The carrier (200) comprises a first wall (figure 2b, 202) having an aperture (figure 2b, 204) therethrough, and a snap fit connector (216) arranged to receive the cylindrical cell (100). When the cylindrical cell (100) is received within the snap fit connector (216), the first end surface (figure 1a, 104) of the cylindrical cell (100) is arranged to abut the first wall (figure 2b, 202), such that the first terminal (figure 1a, 101) but not the second terminal (figure 1a, 103), is accessible via the aperture (figure 2b, 204). A cylindrical cell test assembly comprising the carrier (200) is also specified.

Description

Carrier and Assembly for Testing Cylindrical Cells

TECHNICAL FIELD

Aspects of the invention relate to a carrier and to an assembly for testing cylindrical cells. Particularly, but not exclusively, for testing cylindrical cells for use in automotive battery packs.

BACKGROUND

There has recently been increased interest in hybrid and electric vehicles. One of the challenges faced in the production of such vehicles is to improve the characteristics of the batteries used to power the traction motor (or traction motors). It is generally desirable for vehicle traction batteries to provide a high energy density, to be capable of rapid charging, and to be capable of providing a high peak power output. It is also essential that the thermal characteristics of vehicle batteries are such that overheating of the battery will not occur during any expected use case.

A traction battery of an electric or hybrid vehicle typically comprises one or more battery modules, each module comprising a plurality of rechargeable cylindrical cells.

Given the importance of the properties of the cylindrical cells in determining the overall properties of the vehicle battery, it is often desirable to perform various tests on a large number of cylindrical cells. Such testing has hitherto been a highly labour intensive process.

It is an object of embodiments of the invention to at least mitigate one or more of the

problems of the prior art.

SUMMARY OF THE INVENTION

According to an aspect of the invention for which protection is sought there is provided a carrier for securing a cylindrical cell having a first end surface, a second end surface and a cylindrical surface located between the first and second end surfaces, the cell comprising a first terminal defined by the first end surface and a second terminal defined by the second end surface and the cylindrical surface, the carrier comprising: a first wall having an aperture therethrough; and a connector arranged to receive the cylindrical cell, wherein, when the cylindrical cell is received within the connector, the first end surface of the cylindrical cell is arranged to abut the first wall, such that the first terminal but not the second terminal is accessible via the aperture. Advantageously, the risk of a short circuit between the first and second terminals being created is substantially reduced or eliminated by a carrier according to the present invention. This may obviate the need to apply an insulating coating around the gap between the first and second terminals, thereby significantly reducing the time required to prepare a cylindrical cell for testing.

In an embodiment the connector is a snap fit connector. Such a connector provides a convenient means to connect the cell to the carrier.

The first terminal is typically a positive terminal and the second terminal is typically a negative terminal. However, it will be understood that the terminals may be the other 15 way around in some embodiments.

In an embodiment the carrier further comprises a second wall facing the first wall, wherein the snap fit connector is defined in the second wall.

In an embodiment, the snap fit connector comprises an end stop arranged to abut the second end surface when the cylindrical cell is received within the snap fit connector, the end stop being spaced apart from the aperture by a distance substantially equal to a length of the cylindrical cell, whereby longitudinal movement of the cell within the snap fit connector is substantially prevented. Advantageously, this and shows correct positioning of the cell within the carrier stop In an embodiment, the first wall comprises a circular recess defined around the aperture, the circular recess having a diameter greater than a diameter of the aperture and substantially equal to the diameter of the cylindrical cell. Advantageously, this ensures that access to the second terminal via the aperture is substantially prevented.

In an embodiment the carrier further comprises a base having a location feature defined thereon, the location feature being arranged to locate the carrier on a tray. Optionally, the location feature comprises one or more slots. The tray may have electrical connections provided at one or more predetermined locations. Accordingly, the location features and show that the carriers on cells are appropriately positioned relative to the electrical connections.

In an embodiment the carrier further comprises a securing means arranged to secure one or more wires. Advantageously, this prevents trailing wires from causing short circuits between the first and second terminals.

In an embodiment, the securing means comprises a socket arranged to receive and secure an end connector.

Optionally, the carrier is formed from cast nylon, for example nylon 6, optionally with lubricating additives. A suitable material is available under the trade name Oilamid.

According to a further aspect of the invention for which protection is sought, there is provided a test assembly comprising a carrier as described above and further comprising the tray, wherein the tray is provided with a complementary feature arranged to engage the location feature, thereby to locate the carrier on the tray.

In an embodiment, wherein the complimentary feature comprises a protrusion arranged to be located within the slot.

According to a further aspect of the invention for which protection is sought, there is provided a cylindrical cell test assembly comprising a cylindrical cell and a carrier, the cylindrical cell having a first end surface, a second end surface and a cylindrical surface disposed between the first and second end surfaces, wherein a first terminal is defined by the first end surface and a second terminal is defined by the second end surface and the cylindrical surface, the carrier comprising: a first wall having a first aperture therethrough; and a connector arranged to receive the cylindrical cell, wherein, when the cylindrical cell is received within the connector, the first end surface is arranged to abut the first wall such that the first terminal but not the second terminal is accessible via the aperture.

In an embodiment the connector is a snap fit connector.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which: Figure 1 is an illustration of a typical cylindrical cell (PRIOR ART); Figures 2A-C show different views of a cylindrical cell test assembly in an embodiment of the present invention; Figure 3 shows a cross section taken along plane A-A of the cylindrical cell test assembly shown in figures 2A-C; Figure 4 shows a plurality of the cylindrical cell test assemblies shown in figure 2A-C attached together using spacers; and Figure 5 shows a tray on which the test assemblies shown in figures 2-4 may be mounted, according to an embodiment of the present invention.

DETAILED DESCRIPTION

Figures 1A-D show different views of a conventional cylindrical cell 100. Cells 100 are widely available in a variety of different sizes. For example, in traction batteries for vehicles cells having a diameter D of 21mm and a length L of 70mm are often used.

Such cells are typically referred to as 21700 cells (the first two numbers referring to the diameter D, in mm, and the last three numbers referring to the length L, in tenths of mm). However, it will be understood that other sizes of cell may also be used in embodiments of the present invention.

As will be well understood by the skilled person, the cell 100 comprises a positive terminal 101 defined by the first end surface 104, and a negative terminal 103 defined by the second end surface 105 (located at the opposite end of the cell to the first end surface) and the cylindrical surface 102 between the first and second end surfaces. The cells as supplied are not conventionally provided with an insulating wrap, so the positive and negative terminals are only separated by a relatively narrow gap 106. In the event that a conducting material bridges the gap 106, there is a significant risk that the cell will rapidly discharge, potentially causing the cell to overheat. Accordingly, it is necessary for operators to take great care when testing cells for use in vehicle batteries. Indeed, it has often been necessary for operators to manually apply an insulating layer onto part of the cell 100 so as to reduce the risk of a short circuit occurring during a testing procedure. This process is labour intensive, and therefore significantly increases the cost associated with testing large numbers of cylindrical cells.

As shown in figures 2A-C, the present invention provides a carrier 200 for holding a cell 100 of a specific size during a testing procedure. In the illustrated embodiment, the cell 100 is a 21700 cell, although it will of course be understood that the present invention is equally applicable to cells of different sizes. In the arrangement shown a positive terminal connection 191 is connected to the positive terminal 101 of the cell 100 and a negative terminal connection 193 is connected to the negative terminal 103 of the cell 100.

The carrier 200 comprises a first wall 202, a second wall 210 parallel to the first wall, and a base 214 connecting the first and second walls. The first wall 202 has an aperture 204 defined therein. The first wall 202 also has a circular recess 206 defined around the aperture 204 on the side of the first wall that faces the second wall. The diameter of the aperture 204 is selected to be less than the diameter of the cylindrical cell, so the cylindrical cell cannot pass through the aperture, and the diameter of the circular recess 206 is selected to substantially correspond to the diameter of the cylindrical cell, so that the first end of the cylindrical cell may be located within the recess, thereby preventing radial movement of first end of the cylindrical cell and allowing access to the first terminal 104 via the aperture 204.

The second wall 210 comprises a snap fit connector 216, which is arranged to receive and secure the cylindrical cell 100 at the second end. As best seen from the cross section shown in figure 3, the snap fit connector is also provided with an end stop 218, which is spaced apart from the base of the recess 206 by a distance substantially corresponding to the length L of the cylindrical cell 100. Accordingly, the cylindrical cell 100 may be secured within the carrier 200 by placing the first end into the recess 206 and pushing the second end into the snap fit connector 216. When the cylindrical cell is in place, the cell is prevented from moving in radial directions relative to the length, or longitudinal axis, of the carrier by the recess 206 and the snap fit connector 216, and the cell is prevented from moving relative to the carrier in axial directions by abutment against the end stop 218 and the base of the recess 206. The position and orientation of the cell 100 relative to the carrier is therefore fixed in all degrees of freedom (apart from the rotation about the longitudinal axis of the cell, which is arbitrary since a cylindrical cell 100 is rotationally symmetrical about that axis).

When the cylindrical cell 100 is located within the carrier 200, the first terminal 104 is only accessible via the aperture 204, and the second terminal is not accessible via the aperture 204. This feature provides an important benefit, as it significantly reduces the risk of a short circuit between the first and second terminals being created whilst the cell is located within the carrier. Accordingly, the present invention obviates the need to apply an insulating layer around the gap between the first and second terminals, as has previously been necessary when testing cylindrical cells. This significantly reduces the amount of time required for an operator to prepare cylindrical cells for testing, and provides a corresponding increase in the throughput that can be achieved within a testing facility.

The carriers 200 are provided with a 'C' shaped holding means 222, at which one or more monitoring instruments may be secured. For example, a thermocouple having a connecting wire with an end connector for connection to a computer or data logger may be located on the cylindrical surface of the cell 100, and a moulding comprising a dummy socket into which the end connector can be held may be placed within the holding means 222. In this way, when the end connector is not in use to connect to the computer or data logger, it may be securely held within the socket in the holding means 222, thereby obviating the risk of the end connector bridging the gap 106 between the positive and negative terminals and causing a short circuit.

Testing of batteries is typically performed within environment chambers, which are operable to provide conditions that reproduce an expected operating environment. The environment chambers are also provided with electrical connections that enable the cells within the chamber to be connected to a load and/or power supply, so that charging and/or discharging of the cells can be performed within the chamber. According to an embodiment of the present invention, an environment chamber may be provided with one or more trays 300, as shown in figure 5. The trays comprise a plurality of locations at which carriers 200 may be located and at which electrical connections are provided at fixed positions to allow connection to the positive and negative terminals of the cell.

The tray 300 is also provided with a plurality of holes 301 that allow passage of air around the cells during testing, thereby helping to maintain the desired temperature within the environmental chamber.

To ensure that the carriers are positioned at the appropriate position on the tray, each of the carriers 200 are provided with a slot 220, as best seen in figures 20 and 4. The tray 300 is also provided with a corresponding protrusion at each location where a carrier is to be placed. In this way, appropriate positioning of the carriers on the tray can be ensured. As will be well understood by the skilled person, it is important to position the carriers 200 (and therefore the cells 100) at the correct positions on the tray, so that the electrical connections on the tray contact the intended part of the cells 100.

The carriers 200 are also provided with a plurality of spacer sockets 224 into which spacer bars 250 may be inserted. As shown in figure 4, a plurality of the carriers 200 may be connected together using such spacers 250. In this way, a "batch" of carriers 200, each holding a cylindrical cell 100, may be prepared outside an environment chamber, whilst maintaining the required spacing between the carriers so that the batch can be placed directly onto the tray at a location that allows all of the slots 220 to receive a corresponding protrusion on the tray, so that all of the cells 100 can be connected to the required electrical connections.

In the illustrated embodiment, the carriers 200 are moulded from a plastics material. However, it will be understood that other materials and manufacturing processes would also be suitable, provided the material that the carriers are made from is electrically insulating and is capable of withstanding the expected temperatures within the environment chamber. A suitable plastics material may be cast Nylon, in particular Nylon 6. Optionally, lubricating additives may also be included. A suitable material is available under the trade name Oilamid.

In the illustrated embodiment, the end stop 218 is formed as part of the snap fit connector 216 in the second wall 214. However, it will be understood that in some embodiments, the snap fit connector and the end stop may be formed separately, and it is not essential for the second wall to be provided at all. For example, the end stop could be provided by a single finger upstanding from the base and spaced apart from the base of the recess 216 by a distance substantially corresponding to the length of the cell that the carrier is configured to hold, and the snap fit connector could be located between the first wall and the end stop.

Although the present invention has been described with respect to an embodiment in which a snap fit connector is provided to prevent movement of the cell in radial directions, it will be understood that other connectors capable of preventing radial movement, such as one or more clamps, would also be suitable.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

CLAIMS1. A carrier for securing a cylindrical cell having a first end surface, a second end surface and a cylindrical surface located between the first and second end surfaces, the cell comprising a first terminal defined by the first end surface and a second terminal defined by the second end surface and the cylindrical surface, the carrier comprising: a first wall having an aperture therethrough; and a connector arranged to receive the cylindrical cell, wherein, when the cylindrical cell is received within the connector, the first end surface of the cylindrical cell is arranged to abut the first wall, such that the first terminal but not the second terminal is accessible via the aperture.
A carrier as claimed in claim 1, wherein the connector is a snap fit connector.
3. A carrier as claimed in claim 2, further comprising a second wall facing the first wall, wherein the snap fit connector is defined in the second wall.
4. A carrier as claimed in any one of clams 1 to 3, wherein the connector comprises an end stop arranged to abut the second end surface when the cylindrical cell is received within the connector, the end stop being spaced apart from the aperture by a distance substantially equal to a length of the cylindrical cell, whereby longitudinal movement of the cell within the connector is substantially prevented.
5. A carrier as claimed in any one of claims 1 to 4, wherein the first wall comprises a circular recess defined around the aperture, the circular recess having a diameter greater than a diameter of the aperture and substantially equal to the diameter of the cylindrical cell
6. A carrier as claimed in any preceding claim, further comprising a base having a location feature defined thereon, the location feature being arranged to locate the carrier on a tray.
7. A carrier as claimed in claim 6, wherein the location feature comprises one or more slots.
8. A carrier as claimed in any preceding claim, further comprising a securing means arranged to secure one or more wires.
9. A carrier as claimed in claim 7, wherein the securing means comprises a socket arranged to receive and secure an end connector.
10. A carrier as claimed in any preceding claim, wherein the carrier is formed from cast Nylon.
11. A test assembly comprising a carrier as claimed in claim 6, or any one of claims 7 to 10 where dependent on claim 6, and further comprising the tray, wherein the tray is provided with a complementary feature arranged to engage the location feature, thereby to locate the carrier on the tray.
12. A test assembly as claimed in claim 11 where dependent through claim 7, wherein the complimentary feature comprises a protrusion arranged to be located within the slot.
13. A cylindrical cell test assembly comprising a cylindrical cell and a carrier, the cylindrical cell having a first end surface, a second end surface and a cylindrical surface disposed between the first and second end surfaces, wherein a first terminal is defined by the first end surface and a second terminal is defined by the second end surface and the cylindrical surface, the carrier comprising: a first wall having a first aperture therethrough; and a connector arranged to receive the cylindrical cell, wherein, when the cylindrical cell is received within the connector, the first end surface is arranged to abut the first wall such that the first terminal but not the second terminal is accessible via the aperture.
14. A cylindrical cell test assembly as claimed in claim 13, wherein the connector is a snap fit connector.