GB2060862A - Vacuum flask - Google Patents

Abstract

A vacuum flask having a double walled internal bottle (1) and a bottle jacket (2) receiving the internal bottle includes an elastic supporting member (3) disposed between an open end of the internal bottle and a spout of the bottle jacket so as to support the opening portion of the internal bottle. The supporting member consists of an U-shaped outer part (13) for engaging the periphery of the opening of the internal bottle and an inner part (16) for supporting an upper end and an inner marginal surface of the same. <IMAGE>

Description

SPECIFICATION Vacuum flask The present invention relates generally to a vacuum flask for the storage of liquids to keep them warm (or cold).

In vacuum flasks, an internal double-walled bottle with a vacuum space between the walls is received within a jacket. The internal bottle is usually made of glass and is thus delicate.

Consequently, to prevent the internal bottle from breakage by external forces, a supporting member for engaging the open end of the internal bottle is provided around the opening therein and another supporting member for engaging the closed bottom end may be provided, so that the internal bottle can be held within the jacket with the outer surface of the internal bottle spaced from the inner surface of the jacket. Although the internal bottle generally tolerates axial external impact it has a low resistance to sideways impact forces.

For this reason, the supporting member for supporting the open end of the internal bottle in conventional vacuum flasks is made of a flexible and elastic material and is M-shaped, being relatively thick in cross-section with its peripheral surface and upper end being adapted to conform to the inner configuration of the spout of the jacket and its under surface being in contact with the upper marginal surface of the internal bottle along three lines so that it can relieve the internal bottle from external impact.

Such supporting members are adapted to prevent an internal bottle from breakage caused by horizontal external impact. However, they are not really sufficient to accomplish this purpose since when an external force which exceeds the elastic deformation of the member is applied it is transmitted directly to the open end of the internal bottle and causes it to break because of the interposition of the supporting member between the peripheral surface of the opening of the internal bottle and the inside surface of the spout of the bottle jacket.

Further, a supporting member for supporting the open end of an internal bottle is generally thick so that when internal bottles or bottle jackets are not of the correct dimensions the supporting member cannot properly seal the space provided between the internal bottle and the bottle jacket, and in the extreme case, cannot be properly inserted in position.

According to the present invention there is provided a vacuum flask having a double walled internal bottle with an evacuated space between the walls, and a jacket surrounding the internal bottle, and including an elastic support interposed between an open end of the internal bottle and an opening of the jacket for holding the internal bottle within the jacket, said support having a radially outer part of U-shape, which engages the outer periphery of the opening of the internal bottle and engages the external jacket and a radially inner part having ribs which respectively engage the top end and the inner surface of the opening of the internal bottle.

The flask of the invention employs a supporting member which more effectively absorbs impact forces from outside, while the gap between the internal bottle and jacket is well sealed.

In order that the invention may be more clearly understood, the following description is given by way of example only with reference to the accompanying drawings in which: Figure 1 is a fragmentary cross-sectional view of a vacuum flask according to the present invention; Figure 2 is a perspective view of a preferred embodiment of supporting member partially broken away for clarity.

Figure 3 is an enlarged cross-sectional view of the member shown in Fig. 2.

Figure 4 is an enlarged cross-sectional view of another embodiment of supporting member; and Figure 5 is an enlarged cross-sectional view of a further embodiment of supporting member.

In Fig. 1 there is shown a vacuum flask comprising an internal bottle 1 having an inner wall 1 a and an outer wall 1 b both of glass so as to provide a double walled structure defining an evacuated space. The internal bottle 1 is received within a bottle jacket 2 of, for instance, a synthetic resin such as polypropylene, polyethylene or an acrilic nitrile-butadiene resin. Between an opening 1 c of the internal bottle 1 and a spout 2a of the bottle jacket 2 is a supporting member 3 for supporting the open end of the internal bottle 1 so as to hold the internal bottle 1 centrally within the bottle jacket 2. The supporting member 3 may be made of a elastic material such as ethylene-propylene synthetic rubber, acrylic nitrile-butadiene synthetic rubber or styrene-butadiene synthetic rubber.

Figs. 2 and 3 specifically show the supporting member 3 for supporting the open end of the internal bottle 1 and which comprises an outer part 4 and an inner part 5. The outer part 4 has a substantially U-shaped crosssection and is provided with an outer wall 11, an inner wall 1 2 and a bottom wall 1 3 interconnecting the inner and outer walls 11 and 1 2. The inner part 5 is provided with a radial flange 14 which projects toward the inside at the mid-height or slightly above of the inner wall 12, and circular rims 15, 1 6 and 15', 16' which are arranged on both sides of the flange 1 4 at the middle and the radially inner end thereof.

Due to the configuration of the supporting member, when an external impact force is applied in the direction of the arrow 6 or 6' as shown in Fig. 1, the outer wall 11 of the outer part 4 is elastically deformed and the bottom wall 1 3 of the outer part 1 4 is also elastically deformed so that the applied force is mostly converted into internal stresses and will not be transmitted to the opening portion 1 c of the internal bottle.

Further when the external impact force is applied in the vertical direction of the arrow 7 or 7' as shown in Fig. 1, the force is absorbed for the most part' by way of internal stress created by elastic compressive deformation of the flange 14 and raised rims 15, 15' and 16, 16'. The external vertical force is also partially absorbed by the outer part 4 of the supporting member 3.

The supporting member 3 for supporting the open end of the internal bottle gives a seal with the internal bottle 1 which is reliable because of the raised rims 15, 1 6 and the inner wall 1 2 of the supporting member 3.

These can fit flexibly and sealingly to the configuration of the open end of the internal bottle due to their thickness and elasticity, even if the configuration or the dimensions of the open end 1 c of the internal bottle 1 the bottle jacket 2 and the supporting member 3 may be reliable due to the upper ends 17, 1 8 of the outer part 4 and the raised rims 15', 16' of the inner part 5 fitting against the inner surface of the bottle jacket 2.

Fig. 4 shows another embodiment of supporting member for a vacuum flask according to the present invention, in which the upper ends 1 8 of the outer and inner walls, 11, 1 2 of U-shaped configuration have radial rims. In still another embodiment of supporting member as shown in Fig. 5, the outer wall 11 and the inner wall 1 2 are interconnected by means of spaced ribs 1 9 which serve as means to increase the absorbing power of the supporting member in certain positions, that is, the impact force which can be absorbed varies with the height above the bottom of the U-shaped outer part. In this way, supporting members which are suitably adjusted as to absorbing power corresponding to the sizes and uses of vacuum flasks can be easily obtained. It will be apparent that the absorbable force may be varied by using materials which differ in physical properties or by varying the distance between the outer wall 11 and the inner wall 12.

The supporting member having the construction described above may be used for supporting the bottom of a vacuum bottle. In this case the vacuum bottle can be manufactured at reduced cost by using the same supporting members for both locations.

Claims (8)

1. A vacuum flask having a double walled internal bottle with an evacuated space between the walls, and a jacket surrounding the internal bottle, and including an elastic support interposed between an open end of the internal bottle and an opening of the jacket for holding the internal bottle within the jacket, said support having a radially outer part of U-shape, which engages the outer periphery of the opening of the internal bottle and engages the external jacket, and a radially innter part having ribs which respectively engage the top end and the inner surface of the opening of the internal bottle.

2. A vacuum flask as claimed in claim 1, wherein the upper ends of the outer, Ushaped, part of said supporting member have radial rims.

3. A vacuum flask as claimed in claim 1, wherein the outer part of said supporting member has a plurality of spaced apart ribs which interconnect the upper ends of said Ushaped outer part.

4. A vacuum flask according to claim 1, wherein the supporting member is of one of ethylene-propylene, synthetic rubber, acrylicnitrile-butadiene synthetic rubber, and styrenebutadiene synthetic rubber.

5. A vacuum flask according to any preceding claim, wherein the internal bottle is of glass.

6. A vacuum flask according to any preceding claim, wherein the inner part of the support includes a flange extending radially toward the internal bottle, said flange being provided with the ribs which project from both sides of the flange at the middle position and its radially inner end, the ribs at the middle position being in contact the under surface of said bottle jacket and the top of the open end of said internal bottle and the ribs at the inner end being in contact with the under surface of said bottle jacket and the inner peripheral surface of the opening in the internal bottle.

7. A vacuum flask constructed and arranged substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 3 of the accompanying drawings.

8. A vacuum flask according to claim 7 modified substantially as hereinbefore described with reference to and as illustrated in Fig. 4 or Fig. 5 of the accompanying drawings.