THERMALLY INSULATED CONTAINER

Description

FIELD OF THE INVENTION

The present invention relates generally to thermally insulated containers. More particularly, the present invention relates to a form of vacuum flask for maintaining the temperature of its contents, either hot or cold, for extended periods.

BACKGROUND OF THE INVENTION

Various thermally insulated containers for maintaining the temperature of their contents, whether hot or cold, are known. In all cases, these insulated containers aim to minimize heat transfer between the interior and the exterior. Heat flows from a region of higher temperature to a region of lower temperature and occurs through three primary modes: conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between materials. Convection involves the transfer of heat through the movement of fluids (liquids or gases). Radiation is the transfer of heat through electromagnetic waves.

U.S. Pat. Nos. 2,880,899 and 3,028,984 are examples of thermally insulated containers that feature vacuum-insulated, double-walled bottles received in a protective jacket made of metal, plastics, or the like.

Additionally, U.S. Pat. No. 4,399,919 describes coating one or both walls of a double-walled vacuum vessel with a reflective layer to prevent radiation from reaching the inside of the flask, and vice versa. Alternately, U.S. Pat. No. 4,997,124 teaches the use of an activated foil of a metal from metals such as copper, titanium and zirconium. Another example is U.S. Pat. No. 11,702,271, which discloses disposing reflective material in the evacuated space between the walls of the double-walled vessel.

Cryogenic storage dewars are also well-known. For example, U.S. Pat. No. 3,698,200 describes a vacuum-jacketed cryogenic storage dewar, in which a plurality of spaced-apart radiation shields are placed between the inner storage tank and the outer shell. U.S. Pat. No. 4,154,363 discloses a double-walled cryogenic storage container provided with a vacuum space and a composite multi-layer insulation. The insulation consists of thin radiation layers separated by precompressed sheets weighing less than 2 gms/ft.², composed of selected organic fibers of at least 1 micron diameter bonded together and having a water regain value less than 1%; and activated carbon absorbent.

Other examples of thermally insulated containers can be found in U.S. Pat. Nos. 3,844,450; 4,351,451; 10,723,538; 11,008,153; 11,375,835; and 11,548,717; and 11,812,875; U.S. patent application publication Nos. 2010/0146992; and 2017/0305641; Japanese patent No. 6515905: Japanese patent application No. 2024505629; European patent No. 3813613; German patent application No. 102022212394; and PCT int'l application publication Nos. WO2018/093776; and WO2019/014463.

Additionally, U.S. patent application publication No. 2024/0054984 describes a system designed to reduce sound noise within a receptacle through vacuum separation, distinctly separate from its use in thermal insulation.

Despite these advancements, vacuum insulation is unable to completely envelop the entire surface area, necessitating the inclusion of a physical support structure for the internal container, forming a thermal bridge at the neck. This thermal bridge leads to 30-70% heat exchange depending on the design of the container. The problem of heat dissipation via thermal bridges is exacerbated in cryogenic storage due to the substantial temperature disparity, leading to increased heat transfer. Hence, there remains a need for improvements in the field of thermally insulated containers.

SUMMARY OF THE INVENTION

What is desired therefore, is a thermally insulated container which overcomes at least some of the problems associated with the prior art.

Heat conduction through a material depends on the thermal conductivity k, the cross-sectional area A, the temperature difference ΔT, and the length L of the material. The rate of heat transfer Q is given by Fourier's law of heat conduction:

Q = kA ⁢ Δ ⁢ T L

The present invention aims to minimize the conductive heat transfer (Q) through container in a container design which extends the length of the thermal bridge (L). Extending on this design, magnetic levitation removes any physical contact between the containers, eliminating conduction (k=0). Furthermore, multiple layers of vacuum and reflective coating minimize the heat exchange to a minimum by reducing convection and radiation mode of heat transfer, respectively.

According to one embodiment of the present invention, the thermally insulated container has an outer container body, an inner container body, an inner container lid, and an outer container lid. Both inner and outer container bodies have an insulating double wall with a vacuum between them.

Insulated spacers are positioned laterally between the inner and outer container bodies to prevent the side walls of the inner and outer container bodies from touching each other. The insulated spacers are arranged radially around the side walls so they can be aligned to allow the inner container body to be inserted into the outer container body and misaligned by rotating the inner container body relative to the outer container body. This misalignment interferes with the inner container body, keeping it from falling out of the outer container body, for example, when a user inverts the thermally insulated container to pour out its contents. During its resting condition, these insulated spacers preferably do not touch with each other. Additionally, there is an insulating spacer positioned between the bottoms of the inner and outer container bodies to prevent the bottom walls of the inner and outer container bodies from touching each other. The bottom insulating spacer includes an upstanding wall to catch, center and frictionally hold the inner container body in position relative to the outer container body. The insulated spacers are made from low thermally conductive materials and may include shock-absorbing properties. Examples of materials useful for making the insulated spacers include rubber, plastic, foam, and aerogel. Magnets can also be used in these insulated spacers to adhere and hold the inner container body in position relative to the outer container body.

According to another embodiment of the present invention, the bottom insulating spacer is replaced with an electromagnetic levitator comprising a magnet and an electromagnet, drawing electricity from a power plug. Alternatively, instead of an electromagnetic levitator, a pair of repulsive magnets may be used to keep the bottoms of the inner and outer container bodies physically spaced apart.

An inner lid is provided to close the opening of the inner container body in an airtight and watertight manner. Similarly, an outer lid is provided to close the opening of the outer container body in an airtight and watertight manner, ensuring that the lids do not contact one another when closed on their respective inner and outer container bodies, thereby enhancing thermal isolation. The lids are threaded onto the inner and outer container bodies in a conventional manner.

According to another embodiment of the present invention, a pipe is incorporated into the outer lid, equipped with a closable valve, for connection to a vacuum pump. This allows the vacuum pump to evacuate the air inside the outer container, forming a third vacuum space between the interior of the inner container and the exterior.

According to yet another embodiment of the present invention, each lid is provided with a magnet, which holds the lids together when removed from the thermally insulated container, helping to prevent them from being misplaced.

According to yet another embodiment of the present invention, the insides of the inner and outer containers are coated with reflective linings to minimize the radiative mode of heat transfer between the interior of the inner container and the exterior.

According to yet another embodiment of the present invention, more than two container bodies may be nested together.

Therefore, according to one aspect of the present invention, there is disclosed a thermally insulated container comprising:

• • an outer thermal container having an outer container body and an outer lid secured to the outer container body, the outer container body being formed with double walls and a vacuum in between; and
  • an inner thermal container positioned inside of, and spaced apart from, the outer thermal container, the inner thermal container having an inner container body and an inner lid secured to the inner container body, the inner container body being formed with double walls and a vacuum in between.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the preferred embodiments of the present invention with reference, by way of example only, to the following drawings in which:

FIG. 1 is a cross-sectional view of a thermally insulated container according to an embodiment of the present invention;

FIG. 2 is a detail of area 2 in FIG. 1;

FIG. 3 is a detail of area 3 in FIG. 1; and

FIG. 4 is a cross-sectional view of a thermally insulated container according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described in more detail with reference to exemplary embodiments thereof as shown in the appended drawings. While the present invention is described below including preferred embodiments, it should be understood that the present invention is not limited thereto. In the figures, like elements are given like reference numbers. For the purposes of clarity, not every component is labelled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow persons skilled in the art to understand the invention.

FIG. 1 shows thermally insulated container 10 according to an embodiment of the present invention. The thermally insulated container 10 includes an inner container body 12, inserted inside of an outer container body 14. As best seen in FIG. 2, both the inner container body 12 and the outer container body 14 preferably have double walls with a vacuum 16 between them for insulation. However, it is contemplated that in other embodiments the vacuum insulation may be modified or replaced with any other insulating material.

The inner container body 12 is sized and positioned inside of the outer container body 14 in such a way that the top 18 of the inner container body 12 protrudes out of the top 20 of the outer container body 14. This facilitates easy access and handling of the inner container body 12 and its contents 22. Both the inner container body 12 and the outer container body 14 may be constructed of any suitable material, such as metal, plastic, glass, rubber or any combination of these materials. Without limitation, the inner container body 12 can be configured to store contents 22 such as food, beverages (including milk), as well as scientific and medical products and samples, or cryogens such as liquid nitrogen or helium with its size, shape, and structure adapted accordingly.

An inner lid 24, which includes a seal 26, attaches removably to the inner container body 12 in a manner that completely encloses and seals the opening at the top 18 of the inner container body 12. This ensures that there is no leakage of air or contents 22 into or out of the inner container body 12. The inner container body 12 and the inner lid 24 together define an inner thermal container. Additionally, an outer lid 28 that also includes a seal 26 attaches removably to the outer container body 14 in a manner that completely encloses and seals the opening at the top 20 of the outer container body 14, ensuring that there is no leakage of air into or out of the outer container body 14. The outer container body 14 and the outer lid 28 together define an outer thermal container. Good results have been obtained using seals 26 made from silicone. The inner and outer lids 24,28 may be secured to the inner and outer container bodies 12 and 14 by any means that ensures an airtight and watertight seal to be formed between them. In this regard, good results have been obtained using complementary threads on the inner and outer lids 24,28 and the tops 18,20 of the inner and outer container bodies 12,14. Preferably, the inner and outer lids 24,28 are spaced apart to avoid contact with one another when secured to the respective inner and outer container bodies 12,14. Spacing the inner and outer lids 24,28 apart in this manner prevents conductive heat transfer between them.

Advantageously, the inner and outer lids 24,28 may each be provided with one or more magnets 30, such as neodymium magnets. This allows the inner and outer lids 24,28 to be magnetically attached to each other for safekeeping when removed from the inner and outer container bodies 12,14.

Additionally, one or more insulated spacers 32 may be provided between the inner and outer container bodies 12,14 to ensure that there is no physical contact between them. Spacing the inner and outer container bodies 12,14 apart in this manner reduces or prevents conductive heat transfer between them. The one or more insulated spacers 32 may be attached to the outer wall of the inner container body 12, the inner wall of the outer container body 14, or to both, as shown in the example in FIG. 1. Preferably, a plurality of insulated spacers 32 are arranged on the inner wall of the outer container body 14, and/or the outer wall of the inner container body 12.

In addition to keeping the inner and outer container bodies 12,14 spaced apart, the one or more insulated spacers 32 may also be adapted to prevent physical damage, stabilize the inner container body 12 within the outer container body 14 to prevent wobbling, and facilitate easy pouring of the contents 22 from the inner container body 12. Furthermore, the insulated spacers 32 may be positioned radially on the inner wall of the outer container body 14, and the outer wall of the inner container body 12, such that they align or misalign by rotating the inner container body 12 relative to the outer container body 14. The inner container body 12 can be inserted into and removed from the outer container body 14 when the insulated spacers 32 are misaligned. However, when the inner container body 12 is inserted within the outer container body 14 and rotated to align the insulated spacers 32, it becomes trapped due to interference between the insulated spacers 32 on the inner wall of the outer container body 14 and those on the outer wall of the inner container body 12. The ability to trap the inner container body 12 inside the outer container body 14 in this manner allows a user to pour out the contents 22 from the thermally insulated container 10 without worrying about the inner container body 12 slipping out of the outer container body 14. At the same time, the inner container body 12 remains easily removable from the outer container body 14 for cleaning. Additionally, when separated from one another, the inner container body 12 and the outer container body 14, along with their respective lids 24,28, can be used independently, albeit with reduced insulating capability.

Preferably, an additional insulating spacer 34 may be positioned between the bottoms of the inner and outer container bodies 12,14 to prevent the bottom walls of the inner and outer container bodies 12,14 from contacting each other. Spacing the inner and outer container bodies 12,14 apart in this manner reduces or prevents conductive heat transfer between the inner and outer thermal containers when the inner and outer lids 24,28 are secured to the respective inner and outer container bodies 12,14. Preferably, the bottom insulating spacer 34 may be made from materials such as rubber, plastic, foam, aerogel, or any other material with low thermal conductivity and shock-absorbing properties.

As best seen in FIG. 3, the bottom insulating spacer 34 may include an upstanding wall 36 to catch, center and frictionally hold the inner container body 12 in position relative to the outer container body 14.

It is also contemplated that the insulated spacers 32 and/or the bottom insulating spacer 34 may be replaced with repelling magnets (not shown), positioned and arranged between the inner and outer container bodies 12,14 to maintain the inner and outer container bodies 12,14 spaced apart by magnetic stabilization. All such embodiments are comprehended by the present invention.

Thermal losses due to conductive mode of heat transfer may be further decreased by removing the air in the space 38 between the inner and outer container bodies. Accordingly, some embodiments may be provided with a means to evacuate the space 38 with a vacuum pump (shown). For example, the outer lid 28 may be provided with a conduit, such as a pipe 40 that passes through it. The exterior end 42 of the pipe 40 is configured to connect to a vacuum pump located on the exterior of the thermally insulated container 10, and the interior end 44 of the pipe 40 is disposed in the space 38 when the outer lid 28 is secured to the outer container body 14. Furthermore, a valve 46 may be incorporated into the pipe 40 to allow a user to seal the vacuum in the space 38 before disconnecting the vacuum pump. Afterwards, the user would release the vacuum in the space 38 by opening the valve 46 before unscrewing the outer lid 28 from the outer container body 14.

However, it is contemplated that the outer container body 14 may be provided with the pipe 40, rather than the outer lid 28. Furthermore, the pipe 40 may be entirely omitted in some embodiments, in which case the space 38 between the inner and outer container bodies 12,14 may remain filled with air, since air is be considered a sufficient thermal insulator for some applications. All such embodiments are comprehended by the present invention.

Referring now to FIG. 4, there is shown another embodiment of the thermally insulated container 11, which is similar to the thermally insulated container 10 described above with reference to FIGS. 1-3. However, in this embodiment, the bottom insulating spacer 34 is replaced with an electromagnetic levitator 48. The electromagnetic levitator 48 includes a permanent magnet 50 positioned at the bottom of the inner container body 12, and an electromagnet 52 at the bottom of the outer container body 14. The electromagnet 52 is powered by electricity from a power plug 54 on the outer container body 14, which then connects to an external power supply 56. When energized, the electromagnet 52 exerts a repelling magnetic force on the physical magnet 50, causing the inner container body 12 to rise above the bottom of the outer container body 14 and levitate, thereby eliminating physical contact between the bottoms of the inner and outer container bodies 12,14. It is also contemplated that the permanent magnet 50 may be replaced with a second electromagnet 52. All such embodiments are comprehended by the present invention.

In some embodiments of the present invention, the thermally insulated container may have a plurality of container bodies with lids nested one within the other, in the manner described above. For example, the thermally insulated container 10 may comprise an inner container body contained inside an intermediate container body, which is itself contained within an outer container body.

In some embodiments of the present invention, the inner surfaces of the double-walls forming the inner and outer container bodies 12,14 may be coated to provide reflective linings 58, as best seen in FIGS. 2 and 3. The reflective linings 58 may be made from materials such as Mylar, silver, or any other highly reflective material.

The addition of these reflective linings 58 helps to minimize the radiative mode of heat transfer between the contents 22, the inner container body 12, and the outer container body 14.

Having described the invention above, it will now be understood that the desired contents 22 are stored inside of the inner thermal container which includes the inner container body 12 and the inner lid 24. The inner thermal container is positioned inside of, and spaced apart from, the outer thermal container using insulated spacers 32 at the sides and a bottom insulating spacer 34. Both inner and outer container bodies are preferably formed with double walls and a vacuum in between.

This arrangement ensures that the thermal bridge at the neck of a conventional dewar flask is extended such that the conductive heat must travel from the neck of the outer thermal container to the bottom insulating spacer 34 and then to the inner thermal container, before reaching the stored contents 22 (or vice versa if the environment is colder compared to the stored contents 22). As the length of the thermal bridge is greatly increased, according to Fourier's law of heat conduction, the conduction will be dramatically reduced. Moreover, multiple layers of vacuum and/or space 16,38, further reduce the convection mode of heat transfer and the multiple reflective linings will minimize the radiative heat transfer.

While reference has been made to various preferred embodiments of the invention, other variations, implementations, modifications, alterations and embodiments are comprehended by the broad scope of the appended claims. Some of these have been discussed in detail in this specification and others will be apparent to those skilled in the art. Those of ordinary skill in the art having access to the teachings herein will recognize these additional variations, implementations, modifications, alterations and embodiments, all of which are within the scope of the present invention, which invention is limited only by the appended claims.