The present disclosure relates to a pressure compensating enclosure and uses thereof.

Pressure compensating enclosures are useful in a wide range of applications to negate or mitigate the effects of changes, in use, in a pressure differential between an internal pressure within the enclosure and an external pressure outside the enclosure. For example, pressure compensating enclosures can be useful in subsea applications to negate the effects of changes, in use, in the pressure differential between the internal pressure within the enclosure and the external pressure outside the enclosure, which may be caused as a result of pressure and/or temperature changes with changes in depth. Such a pressure compensating enclosure may be used to house and protect a device such as an electrical device, e.g. a transformer, an electro-chemical cell or a battery.

In oceanography, underwater autonomous vehicles (UAVs) and remote operated vehicles (ROVs), along with many other subsea devices, are used to study regions of the ocean. UAVs may be submerged up to or over 6000m deep in the sea and as such they can experience high pressures in the region of 60MPa. Such UAVs and ROVs may experience significant changes in temperature, e.g. between surface temperatures of 25°C or more in some parts of the world and much lower temperatures at depth. Such UAVs and ROVs are typically powered by batteries. A battery may change volume over its lifetime and due to its state of charge or temperature. As such, any housing or enclosure around the battery needs to remain equalised despite of any volume change by the batteries or changes in external pressure.

Typical existing commercial means for housing electro-chemical cells or batteries in subsea applications comprise either a heavy, substantial outer enclosure operable to resist the external pressure, or use of a connected remote oil compensating circuit which balances the external pressure with the internal pressure of the housing or enclosure.

A first aspect provides a pressure compensating enclosure comprising: a sealed internal volume for receiving, in use, an item or device to be protected, the sealed internal volume being defined at least partially by one or more walls; wherein one or more of the walls comprises one or more sets of folds, the folds being configured to deform preferentially to fold-free sections of the wall(s) in response to changes, in use, in a pressure differential between an internal pressure within the sealed internal volume and an external pressure outside the enclosure.

The set(s) of fold may be considered as a form of bellows or a bellows-type arrangement. In use, when experiencing a change in the pressure differential, any compensatory expansion or contraction of the pressure compensating enclosure will be provided for by movement of the folds in the set(s) of folds. In this way, stress experienced by other portions of the pressure compensating enclosure may be minimised.

One or more of the walls may have one or more sets of folds integrally formed therein.

The pressure compensating enclosure may be suitable for use in underwater, e.g. subsea, applications.

A continuous side wall may surround the sealed internal volume. The continuous side wall may comprise one or more of the sets of folds. One or more of the sets of folds may be integrally formed in the continuous side wall.

In an example implementation, the sealed internal volume may be defined by a first panel, a second panel spaced from the first panel and a continuous side wall extending from the first panel to the second panel.

The first panel and/or the second panel may be fixed to the continuous side wall by any suitable means such as any one or more of: an adhesive, pins, clips, screws, bolts, thermal bonding means, chemical bonding means, or any other suitable means for forming a connection.

The one or more walls may be made from any suitable material or combination of materials. For example, the one or more walls may comprise a metal or a polymeric material, e.g. an engineering plastics material. The polymeric material may comprise polypropylene.

The pressure compensating enclosure may be configured to house any suitable electrical or electrochemical device such as a transformer, electro-chemical cells, or one or more batteries. For example, the pressure compensating enclosure may be configured to house one or more similar or identical electrical or electrochemical devices, such as a plurality of similar or identical battery modules. The pressure compensating enclosure may be configured to house, in use, one or more lithium ion batteries. The item or device to be protected may comprise any device that is susceptible to changing size.

Advantageously, the set(s) of folds is/are configured such that the pressure compensating enclosure is able to expand and/or contract to allow internal and external pressures to remain substantially equalised despite of any volume change by the item or device to be protected. As such, an additional pressure compensating circuit may not be required.

The pressure compensating enclosure may have any suitable shape and/or size.

The sealed internal volume may be of any suitable shape and/or size. For instance, the sealed internal volume may have a cuboidal shape.

The pressure compensating enclosure may comprise a plurality of sets of folds.

The pressure compensating enclosure may comprise a plurality of sets of folds. The pressure compensating enclosure may comprise up to or at least five sets of folds, up to or at least 10 sets of folds, up to or at least 20 sets of folds or up to or at least 50 sets of folds. For instance, the pressure compensating enclosure may comprise two, three, four, five or six sets of folds.

One or more of the set of folds may extend around a substantial portion of, or around an entire perimeter of, the sealed internal volume. Each fold present in a set of folds may extend around a substantial portion of, or around an entire perimeter of, the sealed internal volume.

In an example implementation, the pressure compensating enclosure may comprise a first set of folds and a second set of folds integrally formed in the one or more walls.

The first set of folds may be separated from the second set of folds by a fold-free section of the wall. The first set of folds may be parallel to the second set of folds.

The folds may have any general shape, e.g. a substantially square-cornered arrangement, a zig-zag arrangement, a wavy arrangement, an “S” shape or a “Z” shape. The substantially square-cornered arrangement may be formed by a series of alternating bridging portions and leg portions. In an unstressed state, the leg portions may be substantially perpendicular to the bridging portions.

Each set of folds may comprise the same number, or a different number, of folds as one or more other sets of folds. Each set of folds may comprise any number of folds.

The folds may comprise thinner sections of material than the material forming the fold-free section(s) of the wall(s). The folds may be more flexible than the fold-free section(s) of the wall(s).

For example, one or more of the folds may comprise sections of material having a maximum thickness of no more than 90%, no more than 80%, no more than 70%, no more than 60%, no more than 50%, no more than 40%, no more than 30% or no more than 20% of the fold-free section(s) of the wall(s).

The folds in a given set of folds may have a uniform height. Alternatively, the folds in a given set of folds may not be uniform.

One or more of the folds in a given set of folds may have a height that is substantially equal to a thickness of the wall(s). One of more of the folds in a given set of folds may have a height that is less than a thickness of the wall(s). One or more of the folds in a given set of folds may have a height that is greater than a thickness of the wall(s).

A second aspect provides an assembly comprising a pressure compensating enclosure according to the first aspect with an item or device to be protected disposed within the sealed internal volume.

The item or device to be protected may comprise, for example, a battery, an electrochemical cell, a transformer or a junction box. The battery may be a lithium ion battery.

A substantially incompressible fluid, typically an oil, may at least partially surround the item(s) or device(s) to be protected within the sealed internal volume. The substantially incompressible fluid may substantially entirely surround the item(s) or device(s) to be protected within the sealed internal volume. In an implementation, the item(s) or device(s) to be protected and the substantially incompressible fluid may substantially completely fill the sealed internal volume. In other words, the substantially incompressible fluid may fill the remaining portion of the sealed internal volume not occupied by the item(s) or device(s) to be protected.

As the fluid, e.g. oil, is substantially incompressible, this substantially removes the pressure differential between an internal pressure within the sealed internal volume and an external pressure outside the enclosure when, for example, the enclosure is submerged, in use, and prevents collapse of the pressure compensating enclosure. Hence, lighter and/or thinner materials may be used for the wall(s), thus reducing the overall weight of the assembly.

A third aspect provides a structure containing or having fixed thereto one or more assemblies according to the second aspect.

The structure may comprise a vehicle. The vehicle may comprise a boat, a submarine, an unmanned autonomous vehicle (UAV) or a remote operated vehicle (ROV). The structure may comprise a fixed or substantially stationary structure. The fixed or substantially stationary structure may comprise, for example, a platform, a rig or a buoy located within or on a body of water.

A fourth aspect provides a battery pack comprising one or more battery modules housed within the sealed internal volume of a pressure compensating enclosure according to the first aspect.

The battery pack may comprise any number of battery modules. For instance, the battery pack may comprise at least two battery modules, at least four battery modules, at least six battery modules or at least eight battery modules. The battery pack may comprise up to 10 battery modules, up to 20 battery modules, up to 30 battery modules or up to 40 battery modules.

One or more of the battery modules may comprise a lithium ion battery.

A substantially incompressible fluid, typically an oil, may at least partially surround the battery module(s) within the sealed internal volume. The substantially incompressible fluid may substantially entirely surround the battery module(s) within the sealed internal volume. In an implementation, the battery module(s) and the substantially incompressible fluid may substantially completely fill the sealed internal volume. In other words, the substantially incompressible fluid may fill the remaining portion of the sealed internal volume not occupied by the battery module(s).

A fifth aspect provides a structure, wherein one or more battery packs according to the fourth aspect is/are arranged to provide power to the structure.

The structure may comprise a vehicle. The vehicle may comprise a boat, a submarine, an unmanned autonomous vehicle (UAV) or a remote operated vehicle (ROV).

The structure may comprise a fixed or substantially stationary structure. The fixed or substantially stationary structure may comprise, for example, a platform, a rig or a buoy located within or on a body of water. The skilled person will appreciate that except where mutually exclusive, a feature or parameter described in relation to any one of the above aspects may be applied to any other aspect. Furthermore, except where mutually exclusive, any feature or parameter described herein may be applied to any aspect and/or combined with any other feature or parameter described herein.

In order that the invention can be well understood, it will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a cut away sectional view of a battery pack with a pressure compensating enclosure;

Figure 2 is a perspective view of the battery pack shown in Figure 1;

Figure 3 is a cross-sectional view of a portion of the pressure compensating enclosure shown in Figure 1 and Figure 2; and

Figure 4 shows an underwater autonomous vehicle (UAV) with the battery pack of Figure 1 disposed therein.

Figure 1 and Figure 2 show a battery pack 100. In the illustrated example, the battery pack 100 comprises 16 battery modules 8 arranged within a sealed internal volume defined by a pressure compensating enclosure 1. Each battery module 8 may comprise, for example, a lithium ion battery. The battery pack 100 may be suitable for supplying power to a remotely operated vehicle (ROV) or an underwater autonomous vehicle (UAV) as may be employed in investigations or surveys at depth in bodies of water, including lakes, reservoirs, rivers, estuaries, deltas, seas and oceans. The battery pack may contain any number of battery modules.

A substantially incompressible liquid (not shown), typically an oil, surrounds the battery modules 8 within the sealed internal volume.

The pressure compensating enclosure 1 comprises a first panel 2, a second panel 4 spaced from the first panel 2 and a continuous side wall 6 extending between the first panel 2 and the second panel 4. The first panel 2, the second panel 4 and the continuous side wall 6 define the sealed internal volume. The first panel 2 is substantially rectangular in shape with rounded corners. The second panel 4 is substantially rectangular in shape with rounded corners.

A first edge of the continuous side wall 6 is fixed to the first panel 2 by any suitable fixing means. One or more sealing members (not shown) are arranged to provide a fluid-tight seal between the first panel 2 and the continuous side wall 6.

A second edge of the continuous side wall 6 is fixed to the second panel 4 by any suitable fixing means. One or more sealing members (not shown) are arranged to provide a fluid-tight seal between the second panel 4 and the continuous side wall 6.

The continuous side wall 6 is formed from a single, unitary piece of material. The continuous side wall 6 comprises four side wall portions 7 and four rounded corner portions 9, each corner portion 9 connecting one side wall portion to another side wall portion.

The first panel 2, the second panel 4 and the continuous side wall 6 may be made from any suitable material or combination of materials, typically a plastics material such as polypropylene.

The continuous side wall 6 comprises a first set of folds 10, in which each fold extends continuously around the continuous side wall 6.

The continuous side wall 6 further comprises a second set of folds 10, in which each fold extends continuously around the continuous side wall 6.

The first set of folds 10 is disposed closer to the second panel 4 than the first panel 2. The second set of folds 12 is disposed closer to the first panel 2 than the second panel 4. The first set of folds 10 and the second set of folds 12 are separated by an unfolded section of the continuous side wall 6.

The first set of folds 10 is integrated into the continuous side wall 6. The second set of folds 12 is integrated into the continuous side wall 6. In the illustrated example, the second set of folds 12 includes more folds than the first set of folds 10.

In other implementations, the continuous side wall may comprise only one set of folds. Similarly, the continuous side wall may comprise a plurality of sets of folds. For instance, the continuous side wall may comprise three, four or five sets of folds. The continuous side wall may comprise up to or at least 10 sets of folds, up to or at least 20 sets of folds or up to or at least 50 sets of folds.

The or each set of folds may include any number of folds. For instance, the or each set of folds may comprise a plurality of folds. The or each set of folds may comprise up to or at least five folds, up to or at least 10 folds, up to or at least 20 folds or up to or at least 50 folds.

The folds in the first set of folds 10 and the folds in the second set of folds 12 comprise thinner sections of material than the fold-free section(s) of the continuous side wall 6. For example, the folds in the first set of folds 10 and/or the folds in the second set of folds 12 may comprise sections of material having a maximum thickness of no more than 20% of the maximum thickness of the fold-free section(s) of the continuous side wall 6.

As can be seen particularly clearly in Figure 3, the first set of folds 10 comprises a plurality of folds. The folds are formed by a plurality of alternating bridging portions and leg portions. A first bridging portion 16a extends from a fold-free section of the continuous side wall 6 to a first end of a first leg portion 14a. An inner surface of the first bridging portion 16a is substantially flush with an inner surface of the fold-free section of the continuous side wall 6. The first leg portion 14a extends in a direction through the thickness of the continuous side wall 6 to a second end.

A second bridging portion 16b connects the second end of the first leg portion 14a to a first end of a second leg portion 14b. An outer surface of the second bridging portion 16b is substantially flush with an outer surface of the closest fold-free section(s) of the continuous side wall 6. The second leg portion 14b extends in a direction through the thickness of the continuous side wall 6 to a second end. The second leg portion 14b is parallel to the first leg portion 14a. A third bridging portion 16c connects the second end of the second leg portion 14b to a first end of a third leg portion 14c. An inner surface of the third bridging portion 16c is substantially flush with an inner surface of the closest fold-free section(s) of the continuous side wall 6. The third leg portion 14c extends in a direction through the thickness of the continuous side wall 6 to a second end. The third leg portion 14c is parallel to the second leg portion 14b.

A fourth bridging portion 16d connects the second end of the third leg portion 14c to a first end of a fourth leg portion 14d. An outer surface of the fourth bridging portion 16d is substantially flush with an outer surface of the closest fold-free section(s) of the continuous side wall 6. The fourth leg portion 14d extends in a direction through the thickness of the continuous side wall 6 to a second end. The fourth leg portion 14d is parallel to the third leg portion 14c.

A fifth bridging portion 16e extends from the second end of the fourth leg portion 14d to a fold-free section of the continuous side wall 6. An inner surface of the fifth bridging portion 16e is flush with an inner surface of the fold-free section of the continuous side wall 6.

The folds of the first set of folds 10 comprise chamfered edges at the corners where the bridging portions 16a, 16b, 16c, 16d, 16e and leg portions 14a, 14b, 14c, 14d meet. In other embodiments, the folds of the first set of folds 10 may comprise square edges and/or rounded edges.

In an unstressed state, as illustrated in Figure 3, the bridging portions 16a, 16b, 16c, 16d, 16e are substantially perpendicular to the leg portions 14a, 14b, 14c, 14d. The leg portions 14a, 14b, 14c, 14d are parallel with each other.

As can be seen particularly clearly in Figure 3, the second set of folds 12 comprises more folds than the first set of folds 10. The folds are formed by a plurality of alternating bridging portions and leg portions. A first bridging portion 18a extends from a fold-free section of the continuous side wall 6 to a first end of a first leg portion 20a. An inner surface of the first bridging portion 18a is substantially flush with an inner surface of the fold-free section of the continuous side wall 6. The first leg portion 20a extends in a direction through the thickness of the continuous side wall 6 to a second end.

A second bridging portion 18b connects the second end of the first leg portion 20a to a first end of a second leg portion 20b. An outer surface of the second bridging portion 18b is substantially flush with an outer surface of the closest fold-free section(s) of the continuous side wall 6. The second leg portion 20b extends in a direction through the thickness of the continuous side wall 6 to a second end. The second leg portion 20b is parallel to the first leg portion 20a.

A third bridging portion 18c connects the second end of the second leg portion 20b to a first end of a third leg portion 20c. An inner surface of the third bridging portion 18c is substantially flush with an inner surface of the closest fold-free section(s) of the continuous side wall 6. The third leg portion 20c extends in a direction through the thickness of the continuous side wall 6 to a second end. The third leg portion 20c is parallel to the second leg portion 20b.

A fourth bridging portion 18d connects the second end of the third leg portion 20c to a first end of a fourth leg portion 20d. An outer surface of the fourth bridging portion 18d is substantially flush with an outer surface of the closest fold-free section(s) of the continuous side wall 6. The fourth leg portion 20d extends in a direction through the thickness of the continuous side wall 6 to a second end. The fourth leg portion 20d is parallel to the third leg portion 20c.

A fifth bridging portion 18e connects the second end of the fourth leg portion 20d to a first end of a fifth leg portion 20e. An inner surface of the fifth bridging portion 18e is substantially flush with an inner surface of the closest fold-free section(s) of the continuous side wall 6. The fifth leg portion 20e extends in a direction through the thickness of the continuous side wall 6 to a second end. The fifth leg portion 20e is parallel to the fourth leg portion 20d.

A sixth bridging portion 18f connects the second end of the fifth leg portion 20e to a first end of a sixth leg portion 20f. An outer surface of the sixth bridging portion 18f is substantially flush with an outer surface of the closest fold-free section(s) of the continuous side wall 6. The sixth leg portion 20f extends in a direction through the thickness of the continuous side wall 6 to a second end. The sixth leg portion 20f is parallel to the fifth leg portion 20e.

A seventh bridging portion 18g extends from the second end of the sixth leg portion 20f to a fold-free section of the continuous side wall 6. An inner surface of the seventh bridging portion 18g is flush with an inner surface of the fold-free section of the continuous side wall 6.

The folds of the second set of folds 12 comprise chamfered edges at the corners where the bridging portions 18a, 18b, 18c, 18d, 18e, 18f and leg portions 20a, 20b, 20c, 20d, 20e meet. In other embodiments, the folds of the second set of folds 12 may comprise square edges and/or rounded edges.

In an unstressed state, as illustrated in Figure 3, the bridging portions 18a, 18b, 18c, 18d, 18e, 18f are substantially perpendicular to the leg portions 20a, 20b, 20c, 20d, 20e. The leg portions 18a, 18b, 18c, 18d, 18e, 18f are parallel with each other.

In the illustrated example, the folds in each of the first set of folds 10 and the second set of folds 12 have a uniform height that is substantially equal to a thickness of the continuous side wall 6. Hence, the leg portions 14a, 14b, 14c, 14d, 20a, 20b, 20c, 20d, 20e, 20f each have a length that is substantially equal to the thickness of the continuous side wall 6.

In some implementations, one of more of the folds may have a height that is less than the thickness of the continuous side wall, or greater than the thickness of the continuous side wall.

In some implementations, the folds in the set(s) of folds may not be uniform.

The first set of folds 10 and/or the second set of folds 12 may be considered as a form of bellows or a bellows-type arrangement integrated into the continuous side wall 6.

In use, when experiencing a change in pressure, due to for example a change in volume of any one or more of the battery modules 8, any expansion or contraction of the pressure compensating enclosure 1 will be provided for by movement of the folds in the first set of folds 10 and the second set of folds 12. In this way, stress experienced by other portions and regions of the pressure compensating enclosure 1 may be minimised.

In use, the pressure compensating enclosure 1 may be used with an underwater autonomous vehicle or a subsea remote operated vehicle. One or more of the battery modules 8 may change size for a number of reasons such as changes in its state of charge or changes in temperature or pressure. In particular, when used at depth any pressure differential will need to be compensated for. As the battery modules 8 are surrounded by an incompressible liquid, a change in size of a battery module 8 requires pressure compensation. Upon undergoing a change in size, the first set of folds 10 and the second set of folds 12 allow for the pressure compensating enclosure 1 to expand or contract through opening or closing of the folds. In this way, the change of size of any battery module can be accommodated without stresses being applied to further portions of the pressure compensating enclosure 1.

The pressure compensating enclosure 1 keeps the oil around the battery modules 8. The pressure compensating enclosure 1 does not leak and is robust enough to protect the battery modules 8. Moreover, it will be appreciated that the pressure compensating enclosure 1 provides pressure compensation, in use, without the need for an external oil compensating circuit.

One or more outer surfaces of the pressure compensating enclosure 1 may be adapted in any suitable way for fixing or mounting the battery pack 100 to a support structure at an intended point of use, e.g. within a UAV or ROV. For instance, one or more parts of the first panel 2, the second panel 4 and/or the continuous side wall 6 may be adapted to receive fixing means operable to fix or mount the battery pack 100 to a support structure at an intended point of use.

The folds in the set(s) of folds may have forms other than the generally squarecornered form illustrated in Figures 1 to 3. For instance, the folds may have a zig-zag form or may be wavy in form.

Figure 4 shows an example implementation, in which the battery pack 100 is arranged to provide power to an underwater autonomous vehicle (UAV) 400. The UAV 400 has a main body 402. The battery pack 100 is disposed within the main body 402 of the UAV 400.

It will be appreciated that the pressure compensating enclosures disclosed herein may be employed in applications other than battery packs. Generally, the pressure compensating enclosures may be beneficially employed to protect any internal volume from changes in temperature and/or pressure, e.g. as may be experienced subsea. The internal volume being protected may have any suitable size and shape. In some implementations, the internal volume being protected may have a rectilinear shape. For instance, the internal volume being protected may be generally cuboidal in shape.

In an example implementation, the pressure compensating enclosure may be arranged to protect a junction box or a transformer box, e.g. in an ROV or UAV.

The volume of fluid, e.g. oil, within the pressure compensating enclosure is protected by the pressure compensating enclosure, which can expand and contract.

It will be appreciated that the present disclosure may provide an elegant and cost- effective solution that eliminates the need for an oil compensating circuit such as a connected remote oil compensating circuit. In applications where space- and/or weight-saving are important such as in UAVs and RO Vs used in oceanographic research, the elimination of the need for an oil compensating circuit may be particularly advantageous.

While the invention has been described with reference to certain specific embodiments, various modifications will be apparent to the person skilled in the art without departing from the scope of the application.

It will be understood that the invention is not limited to the embodiments abovedescribed and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.