GB2134620A - Improvements in or relating to pneumatic tube carrier systems - Google Patents

Abstract

This invention is concerned with a pneumatic tube carrier system which comprises a series of lengths of tube to form a tube line connecting a pair of stations and a supply of air under pressure or vacuum to propel a carrier from one station to the other wherein the lengths of tube joining the tube line are flexible enough to enable the tube to be formed into a curve but sufficiently firm to be retained in the curved shape. The tube may have interengaging edge parts (see also Figs. 6-10) or a helical coil (Figs. 11-16). <IMAGE>

Description

SPECIFICATION Improvements in or relating to pneumatic tube carrier systems This invention has reference to pneumatic tube carrier systems. Such systems usually comprise a pair of stations connected by a tube and a supply of air under vacuum and/or pressure is connected to the system to propel a carrier through the tube from one station to another. The two stations may be connected directly the one with the other without intermediate stations; or the system may have intermediate stations and the system be so arranged that a carrier may be despatched from any one of the stations and delivered to a selected other one of the stations. The system may comprise a ring system with a plurality of stations spaced around the ring system and so arranged that a carrier despatched from one of the stations may be delivered to any other one of the stations in the system.

The stations are joined by a tube line made up of a plurality of tube lengths many of which are straight lengths but at various positions along the length of the tube line tube bends are inserted for example to enable the tube to be secured around two walls of a building which are at right angles to each other. The tube lengths including the lengths of tube bends are often made of metal but may be made of plastics material.

The present invention has particular reference to pneumatic tube carrier systems as described in the specifications of British applications for Patent Nos 8105678 and 8105679 and 8303198 and European Patent application No 81300743.2.

It is an object of the present invention to provide a simple but effective form of tube length suitable for use in a pneumatic tube carrier system.

It is a further object of the present invention to provide a simple length of tube for a pneumatic tube carrier system which tube length can be adapted to fit for example the corners of a building without the necessity for providing joints in the tube.

According to the present invention a pneumatic tube carrier system comprises a series of lengths of tube to form a tube line connecting a pair of stations and a supply of air under pressure or vacuum to propel a carrier from one station to the other, wherein lengths of tube forming the tube line are flexible enough to enable the tube to be formed into a curve but sufficiently firm to be retained in the curved shape.

Preferably the lengths of tube each comprises a flexible extrusion wound in the form of a helix with the convolutions of the helix retained together in a substantially airtight condition.

Pneumatic tube carrier systems in accordance with the present invention will now be described by way of example with reference to the accompanying drawings wherein: Fig. 1 is a diagrammatic view of a pneumatic tube carrier system, Figs. 2 and 3 are side views of a part of a tube of the system in two conditions, Fig. 4 is a cross sectional view part of the tube, Figs. 5 and 6 are respectively side views and cross sectional views of a further embodiment of part of a tube of the system, Figs. 7 and 8; 9 and 10; 11 and 12; 13 and 14; and 15 and 16 are respectively side views and cross sectional views of still further embodiments of part of a tube of the system.

As shown in Fig. 1 of the drawings a pneumatic tube carrier system to comprises a pair of stations 1,2 connected by a tube line 3 and a supply of air under vacuum and/or pressure is connected to the system to propel a carrier through the tube line from one station to another. The two stations 1, 2 may be connected directly the one with the other without intermediate stations; or the system may have intermediate stations and the system be so arranged that a carrier may be despatched from any one of the stations and delivered to a selected other one of the stations. The system may comprise a ring system with a plurality of stations spaced around the ring system and so arranged that a carrier despatched from one of the stations may be delivered to any one of the stations in the system.

In particular the system may be of the kind described in the Specifications of our British applications for Patent Nos 8105678 and 8105679 and 8303198 and European Patent Application No. 81300743.2.

The tube line 3 is made up of a length of tube of which the first embodiment is shown in Figs. 2 to 4. The length of tube is formed from an extruded length of strip of plastics material such as polythylene which has a cross section as shown in Fig. 4. The plastics material may be of opaque material but is preferably of transparent plastics material in order that blockages in the tube may be readily detected. In cross section the strip shown in Fig. 4 comprises a hollow rectangular part 5 with a throat 6 in one of the shorter lengths of the rectangular. This throat has sloping sides.

The part 5 also has an extension straight part 7 extending from the other shorter side of the rectangular with a barb 8 on the end of straight part 7. To form the tube the strip is wound on a former of circular cross section for example so that the outer diameter of the tube is 421 (four and one half inches) in the form of a helix with the straight part 7 engaged in the rectangular part 5 of the next adjacent helix. It will be apparent that the barb 8 on the end of the straight part is retained in the rectangular part of the next adjacent convolution by virtue of being located behind the sides of the throat 6, so that the convolutions are interlocked. However the longitudinal part 7 is movable in the rectangular part.Normally for use as a straight section of of tube line the convolutions are spaced close to one another as shown in Fig. 2 to form a straight section of tube line 3.

However the convolutions may be spaced apart as required with the inner end of the barb 8 lying close to the throat 6 similar to the condition as shown in Fig. 4. On the other hand if the tube line is required to be in the form of a bend it is arranged that each barb of the strip is moved fully into the throat of the strip at the inside of the bend and adjacent to the throat 6 of the rectangular part of the outside of the bend. By this means we are able to provide a bend part of a tube line as shown in Fig. 3 with the barb adjacent the respective ends of the rectangular at opposite sides of the tube line a sharp bend is provided.

However if a bend of smaller radius is required the position of the barb 8 within the rectangular opening may be selected to give the required radius of bend.

It will be apparent that it will be possible to locate long lengths of tube line in position (for example around the walls of in ducts in a building) without the necessity for joining one tube length to another tube length. As the tube is flexible long lengths can be carried into the buildings. Typically a length of flexible tube of 1 5 meters may be used but longer lengths could be employed if it could then be handled by more than one man. A second embodiment of tube length is shown in Figs. 5 and 6 of the drawings.The tube length 3 is like the tube length shown in Figs. 2 to 4 being formed from a length of strip of plastics material but the cross section of the strip of plastics material convolutions is different and has a first recess 9 facing in one direction (inwardly) and having a part curvetiere and a second recess 10 facing on the other direction (outwardly) which has a channel slope.When the strip is formed into a tube by being wound into helical convolutions on a former the outer end of the part circular cross sectional recess 9 is engaged in the channel shaped recess 10 (as shown in Fig. 6). The tube may be given a stable characteristic (by having adhesive) as illustrated at 11 to secure the sides of the channel shaped recess to the circular recess for straight lengths of tube line the tube line is retained in a straight condition but for curved tube parts of the tube line is curved by moving the position of the sides of the part circular recess 9 in the channel sloped recess 10.

A further embodiment of the tube length is shown in Figs. 7 and 8. In this embodiment the tube length 3 of plastics material is similar to the tube length 3 as shown in Figs. 5 and 6 of the drawings. However in this case the inwardly facing recess 12 is of castellated shape rather than of part circular shape.

In the embodiment shown in Figs. 9 and 10 which shows a tube length similar of plastics material to that shown in Figs. 7 and 8 the sides of the cross sectional strip have hook shaped portions 13 so arranged that when the strip is formed into convolutions and the sides of the strip interlock with the hook shaped part of one convolution interlocking with the hook shaped part of the next adjacent convolution. The interlocking convolutions are covered by a layer 14 of thermoplastic material.

In the embodiment shown in Figs. 11 and 12 the tube length is formed from a first inner layer of fabric 1 5 (which may be fabric impregnated with water resistant material) wound on a former and a helical coil 16 of spring metal is wound around the first layer of fabric. A second layer 1 7 of impregnated fabric is wound around the helical coil and the areas where the two layers of fabric overlap they are secured together by adhesive as at 1 5. The tube length 1 is sufficiently flexible to enable the tube length to be formed into a curve.

In the embodiment shown in Figs. 13 and 14 the tube length 3 is formed from a helix 18 of plastics material which is flexible and resistant and this helix is embedded in a covering of another plastics material by forming on a former of circular cross section. The plastics material are selected to give the tube length the desired properties of resistance and flexibility so as to be used to transport a carrier from one station to another and to enable such tube length to be curved as the tube length follows the walls of a room etc.

In the embodiment shown in Figs. 15 and 16 a length of helical wire 19 covered with a thermoplastics material covering 20 is formed around a circular former and covered by a layer of thermoplastics material 21 and the covering and the layers are heat sealed together to form a reinforced tube length suitable to convey a pneumatic tube carrier.

By this invention we are able to provide an improved pneumatic tube carrier system with tube lengths joining the stations of the system and made up of flexible lengths of tube to enable the tube to be formed into a curve but sufficiently firm to be retained in the curved shape and capable of having a carrier conveyed through it under the action of air under vacuum or under pressure.

Also by this invention we are able to provide a flexible tube for a pneumatic tube system which can be fitted in position between stations of the tube system. The flexible tube can readily adapt to curves around the corners of a room or to avoid obstructions without the necessity for providing tube bends to join straight lengths of tube together.

It is found that because the tube is made of a helix with a number of convolutions when curved around a bend the bore of the tube remains of constant cross section when so curved because each convolution retains its cross section.

Although the invention has been described with reference to a helical tube having circular convolutions the invention may also be applied to a helical tube of rectangular cross section for use with carriers of rectangular cross section or even of elliptical cross section which is for use with flexible carriers or carriers of elliptical cross section.

Claims (8)

1. A pneumatic tube carrier system comprising a series of lengths of tube to form a tube line connecting a pair of stations and a supply of air under pressure or vacuum to propel a carrier from one station to the other wherein the lengths of tube forming the tube line are flexible enough to enable the tube to be formed into a curve but sufficiently firm to be retained in the curved shape.

2. A pneumatic tube carrier system according to Claim 1 wherein the lengths of tube each comprises a flexible extrusion wound in the form of a helix with the convolutions of the helix retained together in a substantially airtight condition.

3. A pneumatic tube carrier system according to Claim 2 wherein the convolutions of the helix comprise extracted plastics material.

4. A pneumatic tube carrier system according to Claims 2 or 3 wherein the convolutions of the helix of the tube line have a cross section with a hollow rectangular part with a throat on one of the shorter sides and the other shorter side has a barbed extension part to engage the hollow rectangular part of the adjacent convolution.

5. A pneumatic tube carrier system according to Claim 2 or 3 wherein the convolutions of the helix of the tube line has an inwardly facing recess and a channel shaped recess whith the circular recess engaging the channel shaped recess of the adjacent convolution.

6. A pneumatic tube carrier system according to Claim 2 or 3 wherein the convolutions of the helix are formed from a layer of fabric wound on a former with a metal helical coil wound around the fabric and a second layer of fabric covering the helical coil.

7. A pneumatic tube carrier system according to Claim 2 or 3 wherein the convolutions of the helix of the tube line are formed from a helical wire covered with thermoplastics material.

8. A pneumatic tube carrier system constructed and arranged substantially as herein described with reference to the accompanying drawings.