GB1569827A

GB1569827A - Sleeves and tubular assemblies especially for pinch valves and pinch valves embodying such sleeves and assemblies

Info

Publication number: GB1569827A
Application number: GB163877A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-01-09
Filing date: 1978-01-09
Publication date: 1980-06-18

Description

(54) IMPROVEMENTS RELATING TO SLEEVES AND TUBULAR ASSEMBLIES ESPECIALLY FOR PINCH VALVES AND PINCH VALVES EMBODYING SUCH SLEEVES AND ASSEMBLIES (71) I, FRANCIS SUMMERFIELD, a British subject of 9 Dunstarn Drive, Leeds LS16 8EH, Yorkshire do hereby declare the invention for which I pray that a Patent may be granted, and the method by which it may be performed to be particularly described in and by the following statement:: - This invention relates to, in general, pinch valves and more especially tubular sleeves and assemblies, and has particular application to flexible tube assemblies of a type which are suitable for carrying fluent material such as paste, granular material, liquids, slufiies and so on and which are also capable of being squeezed to block off or control flow of the fluent material along the tube, when in a pinch valve.

Conventionally, flexible tubes of this type are not capable of withstanding high internal pressures, i.e. pressures in excess of 100 p.s.i.

and to date have therefore only found limited use.

Attempts have been made to produce flexible tubes of this type which will withstand high internal pressures, but such tubes have usually been moulded in rubber and have been of a greater thickness, the tube wall embodying a canvas reinforcement embedded in the wall of the tube, such canvas being so embedded by being located in the mould during the moulding of the tube. Such tubes have certain drawbacks, and one tube assembly which I have proposed to overcome such drawbacks comprises a flexible tubular member having end flange formations and a fabric reinforcing sleeve lying on the outside of the tubular member and extending between the flange formations.

The previous suggestion also provides a tube assembly comprising a flexible tubular member which has end flange formations and which is of circular outer cross section except over an axial region between the ends thereof, and has internal opposing shoulders at said region which divide the internal tube section at the shoulders into a first portion and a second portion which includes the shoulders, the circumferential internal length of the first portion being equal to the circumferential internal length of the second portion so that the tube can be pinched dosed by a wrapping of the first portion into the second portion and over the shoulders, whilst the flexible tubular member is held in a rigid tube match ing the outside diameter of the flexible tubular member, the tube assembly further including a fabric reinforcing sleeve which lies on the outside of the tubular member and is con structed and adapted to reinforce the tubular member against rupture as a result of high internal pressure, and to flex with the tubular member when pinched, and is separable from the flexible tubular member; and, also such a tube assembly is usable in a pinch valve including a valve casing defining a bore, said bore matching the tube assembly which is located in said bore and a pinching plunger means adapted to engage the tube assembly so that the tube assembly can be pinched closed by a wrapping of the first portion into the second portion and over the shoulders, whilst the tube assembly is held in said casing.

The said sleeve, which is described as being, preferably, of tubular, plain weave construc tion, may have the warp yarns lying axially of the rubber member, and may have the weft yarns lying circumferentially of such tubular member. It is disclosed that by vary ing the amount of weft yarns relative to the warp yarns, the circumferential strength of the sleeve in relation to the pinching flexibility can be varied in order to achieve the best characteristics for use in a pinch valve where the ends of the sleeve and tubular member may well be anchored, but the assembly has to retain circumferential strength coupled with pinchability.

Whilst the suggested tube assembly over comes the difficulties of the known tube assemblies, it is something of a drawback of the suggested fabric sleeve in that the sleeve is required to be circumferentially strong on the one hand, yet on the other hand has to be axially extendable, at least at the side which faces the piston or plunger as it is displaced by the plunger.

This invention aims to provide a fabric sleeve which, inter alia, is usable in a tube assembly as described above, yet which is free of the said drawback.

According to the invention there is provided a fabric sleeve usable around a flexible tube to form a tubular assembly usable in a pinch valve, said sleeve having at least one permanent set pleat folded back onto the sleeve and extending circumferentially of the sleeve thereby to reduce the effective axial length of the sleeve at least over a circumferential por tion of the sleeve, the arrangement being that the sleeve can be arranged around said flexible tube to form a tube assembly for a pinch valve so that when such assembly is pinched, the pleat unfolds allowing the sleeve or at least said sleeve portion to increase its axial length without the sleeve being stretched, or stretched to a significant degree, the permanent set of the pleat causing it to reform when the pinching effect is removed.

There preferably are two of said pleats in the sleeve, said pleats being symmetrically arranged relative to a central radial plane of the sleeve whereat the pinching is to be applied.

The or each pleat preferably in one embodiment may taper from a maximum axial width to zero in each direction from said maximum axial width whilst in another embodiment, the or each pleat may be of even width and may encircle the entire sleeve.

The invention also provides a tube assembly for a pinch valve comprising a flexible tube and a sleeve as aforesaid surrounding and separable from said tube.

Further the invention comprises a pinch valve comprising a casing, a tube assembly as aforesaid in said casing, and a plunger for pinching the tube assembly. The valve may be adapted for connection in a fluent material flow system so that the fluent material can flow through the tube assembly when the assembly is not pinched, and the flow can be blocked or stopped by pinching of the tube assembly, the tube assembly being located so that when pinched the or each pleat unfolds.

Suitable yarns for the sleeve are yarns of polyester and/or yarns of nylon.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings: Figure 1 is a sectional elevation of a previously proposed tube assembly the section being taken on line AA of Figure 2; Figure 2 is a longitudinal section of the tube assembly shown in Figure 1 when the tube assembly is in position in a pinch valve, the section being taken on the line BB of Figure 1; Figure 3 is a sectional elevation showing a detail of the tube assembly as shown in Figure 2; Figure 4 shows a portion d the fabric outer sleeve used in the tube assembly shown in the Figures 1, 2, 3, 6 and 7, in order to show the weave pattern of such fabric sleeve; Figure 5 is an end view of the valve shown in Figure 2, the valve casing halves being shown in partly open condition;; Figure 6 is a sectional elevation similar to Figure 1, but shows the tube in the closed condition; Figure 7 is a side view of a sleeve according to a first embodiment of the invention prior to the formation of pleats therein; Figure 8 is a sectional elevation, similar to Figure 2, showing a pinch valve with a tube assembly including the sleeve of Figure 7, after forming the pleats therein; and Figure 9 is a sectional elevation showing a tube assembly according to a second embodiment of the invention.

Referring to the drawings, and firstly to Figures 1 to 6, the previously proposed tube assembly shown comprises an inner flexible tube 10 of rubber or other resilient material.

The tube 10 has a circular outer cross-section and terminates in end flanges 12 having reverse directed ribs 14 (Figure 3).

The bore of the tube 10 is of circular, even cross-section except over a central region, designated in Figure 2 by reference 16. Over this central region, the tube has internal shoulders 18 which are basically diametrically opposite. Towards the ends of region 16 the shoulders 18 taper to nothing and into the circular inner wall of the tube 10. As well as being formed only over the region 16, the shoulders 18 are formed each within a segment defined by angle 20 (see Figure 1). In the preferred case, this angle 20 is slightly greater than 45". The portions of the inner surface of tube 10 subtended by the remaining segments of angle 22, are of circular and equal, constant wall thickness.

The reason for providing the shoulders 18, is to ensure that when the tube assembly is used in a pinch valve having a circular bore and the tube assembly is pinched closed as shown in Figure 6, rhe portion of the tube to one side of the shoulders wraps smoothly over the shoulders and into the other portion of the tube to the outside of the shoulders, ensuring that there is no creation of high stress points in the region of the shoulders, as would occur if no shoulders were provided.

The tube 10 can be made of high quality rubber compound, and can be relatively thin so rhat, in accordance with manufacturer's requirements, the tube can be of the highest quality from a production point of view.

Such a tube would not in itself withstand a relatively high internal pressure of 100 libs.

per square inch and more, and in order that the tube may carry fluent material at such pressure, it is surrounded by separable circular fabric sleeve 24 which can be knitted or woven, although a plain tubular weave as shown in Figure 4 is preferred. The sleeve can serve as a heat insulator, and will protect the external surface of the rubber tube. The fabric is of a construction and of materials so that it can withstand much higher internal pressures than can the tube 10. In fact, in use of the assembly as shown, it is envisaged that the stresses on the tube assembly created.

by high internal pressures will be absorbed almost entirely by the fabric sleeve.

The yarns of the sleeve, which can be self lubricated during manufacture, are arranged such that the warp threads extend axially of the sleeve, whilst the weft threads extend circumferentially of the sleeve. By this arrangement, variation in the relative strength characteristics of the sleeve in the axial and circumferential directions is readily possible.

It is possible to construct the sleeve so that it has less strength axially than circumferentially. This is because the tube must flex to the closed position indicated in Figure 6, and because during normal use there will be little or no axial stress on the tube assembly even although the assembly carries a fluent material at a pressure in excess of 100 Ibs. per square inch.

Figure 8 shows a sleeve and sleeve assembly according to first embodiment of the invention, and Figure 7 shows the sleeve of Figure 8 before the formation of the pleats therein.

Parts which correspond to parts already described in relation to Figures 1 to 6 have the same reference numerals.

In Figure 8, the sleeve 24 is shown as having two pleats 24A and 24B symmetrically arranged relative to the centre plane of the valve. These pleats are permanent set, having been formed under suitable conditions of heat and pressure as is known in garment manufacture. Each pleat 24A and 24B is folded back onto the sleeve as shown and extends circumferentially of and almost completely round the sleeve, its width tapering in both directions from the top of the sleeve, from a maximum to nothing. The pleats 24A and 24B lie in planes which are inclined relative to said centre plane.

The purpose of the pleats 24A and 24B is to permit the effective length of the top of the sleeve 24 to increase by the amount which it must increase when the tube assembly is pinched by the plunger 300 between the full line position and the broken line position in which the tube assembly 10(24) is pinched closed, to the position shown in Figure 6.

As the pleats 24A and 24B are permanent set, they will recover to the position shown in full lines in Figure 8 when the plunger 300 is retracted. The arrangement of Figure 9 shows that the pleats 24A, 24B are of constant axial width but unfold and refold with pinching and unpinching of the tube assembly.

By providing the pleats 24A and 24B, which unfold between the tube assembly open and closed positions, the sleeve 24 can be maintained free, or substantially free of axial stretching. The sleeve will however at all times support the tube 10 circumferentially against the internal pressure of the fluid being carried therein. The tube 10 of the assembly of Figure 8 or Figure 9 is, although not shown, preferably the same as the tube shown in Figures 1 to 6.

Modified forms of the sleeve according to the invention are possible. For example, the pleats may extend around only half of the circumference of the sleeve.

The sleeve 24 of Figure 8 is shown in Figure 7 before the sleeve 24 is pleated and the pleats set. It will be seen that the ends of the sleeve lie in divergent and symmetrical planes, the difference between the maximum axial length and the minimum axial length of the sleeve is equal to the amount of increase in effective length of the top of the sleeve as the sleeve is pinched between open and closed positions. When the pleats are formed in the sleeve 10 of Figure 7, the ends are brought into parallel relationship.

The sleeve may be constructed of the yarns of any suitable material which can have permanent set pleats, and in the present example yarns of Nylon (Registered Trade Mark) and/or polyester such as Terylene (Registered Trade Mark) are preferred. With such yams, the sleeve can be not only provided with pexrnanent set pleats but can also be cut to length by means of a hot knife, which melts and seals the ends of the yams together, which prevents laddering of the sleeve in use. The sleeve is separable from the tube 10, and in the present example it is preferred that the sleeve end is formed, by a heat setting tool, to follow the end flanges 12 and rims 14 as shown in Figure 3.This ensures that when the tube assembly is in position in a pinch valve, the ends of the tube 10 and also the ends of the sleeve 24 will be held anchored by the connecting flanges or fittings of the valve and pipes to which the valve is connected.

When the tube 10 has the specific internal bore shape as shown in Figure 1 the valve can be used in any position provided that the lowest point of the bore of tube 10 lies within either of the segments 22, and in any such position the valve will be self-draining, which is highly desirable when the valve is to be used under aseptic conditions.

In one suitable construction for the fabric sleeve, this has a circumference of 7.25 inches (this size is given by way of example only) and the warp is based on 840 denier bright high tenacity nylon yarn with a tenacity of 8.5 G.P.D. which gives a strength of just over 7kg. for each individual end. In the warp there are 500 of these ends at 70 ends per inch. When tested as a tube pulling in the warp direction this gives a strength of 3,500 kg. This high strength is essential to give the basic structure a good strength factor and also good elasticity when flexed in use.

For the weft, various yarns have been used but these may be either bright high tenacity polyester or bright high tenacity nylon. The range used to date goes from 400 denier weft up to 2000 denier in the form of a 2 fold 1000 denier polyester. The function of the weft in this tubular fabric is to give high resistance to stretch when the tube is under pressure. This is achieved by combining the number of threads per inch together with the denier or thickness of the yarn used. By using a high number of weft picks per inch (30 to 48) with the correct yarn it is possible to resist pressures of up to 300-500 lbs. per square inch comfortably. The choice of yarn for the weft will also govern both the resistance to strength and the elasticity of the webbing when in use under pressure.It is possible by this weaving application to make changes to suit any requirements called for.

Six examples based on the same basic nylon warp of 500 ends of 850 denier nylon are given below. The weft and picks per inch were changed to vary the resistance to internal pressures.

Sample 9-38 picks per inch 1000 terylene weft 1000 Terylene spool Sample 10-32 picks per inch 2/1000 terylene weft 2/100 spool Terylene Sample 11-32 picks per inch 1770 nylon B weft 940 spool nylon Sample 12-36 picks per inch 1770 nylon weft 940 spool nylon Sample 13-36 picks per inch 1770 nylon weft 1770 spool nylon Sample 11 10 picks per inch 940 nylon weft 2/940 Bt,nylon spool All samples were woven 3i" wide flat.

Tests with samples of 100% polyester yams have been encouraging, and two examples of such samples are as follows: Sample A 100% Polyester Warp-550 Decitex, 230 ends per inch Weft-8 ends 550 Decitex 30 picks per inch Sample B 100% Polyester Warp--550 Decitex-230 ends per inch Weft-6 ends 550 Decitex-34 picks per inch DECITEX IS A REGISTERED TRADE MARK When a tube assembly as described with reference to Figures 7 and 8 or Figures 9 of the drawings is used in a pinch valve, the outer sleeve 24 takes all of the stress created by the higher pressure in the tube assembly, and the valve casing is relatively free of such pressure, enabling a much lighter gauge valve casing to be used, which is desirable, and as the sleeve to the tube can be varied by replacing the sleeve. Furthermore, the pinching forces necessary to close the valve are much less than those required for pinching an equivalent high pressure flexible tube of conventional construction and embodying canvas in the tube wall thickness, and the sleeve is free, or substantially free of any axial stretching when in the pinched condition - as has been explained.

This tube assembly according to the invention could be used in the applications. For example in a peristakic pump.

As shown in Figures 2 and 5, it will be observed that the valve in which the tube assembly 10, 24 is located, comprises basically a pair of similar valve body halves 260, 280 which together define a T-shaped interior space with the tube assembly 10, 24 extending in the arms of this T-space and the valve plunger 300 being located in the leg of the T.

Where the leg meets the arms, the rounded end of plunger 300 can engage the tube assembly 10, 24 to close same. The valve shown in Figure 2 ob the drawings is operated simply by means of an operator's handle 320 and by turning this handle 320, plunger 300 is forced to move up or down in Figure 8 or 9. The lower limit of movement of the plunger 300 is illustrated in Figure 6 and it will be noticed in this position that one tubular member section is pressed into firm contact with the inside of the other section. Figure 5 shows how rhe valve body halves 260 and 280 can be pivoted apart about their axis of hinge pins 282 to enable the tube assembly 10 (24) to be removed for cleaning and, if necessary, replacement, and in fact Figure 2 shows the halves 260 and 280 fully open, the hinge pins being indicated by numeral 282.

The valve without the plunger could be used as a water pipe connection, and the tube assemblies could be fitted in pipelines to allow for moving of the valve plunger positions.

The assembly shown in Figure 8 and in the assembly shown in Figure 9 fitted in the valve casing as shown, in a similar manner, except that the casing is slightly modified. It may be desirable initially to treat the sleeve with a chemical or coating composition in order better to effect the permanent setting of the pleats with the subsequent application of heat and pressure.

WHAT I CLAIM IS:- 1. A fabric sleeve usable around a flexible tube to form a tubular assembly usable in a pinch valve, said sleeve having at least one permanent set pleat folded back onto the sleeve and extending circumferentially of the sleeve thereby to reduce the effective axial length of the sleeve at least over a circumferential portion of the sleeve, the arrangement being that the sleeve can be arranged around said

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Claims

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7kg. for each individual end. In the warp there are 500 of these ends at 70 ends per inch. When tested as a tube pulling in the warp direction this gives a strength of 3,500 kg. This high strength is essential to give the basic structure a good strength factor and also good elasticity when flexed in use.

For the weft, various yarns have been used but these may be either bright high tenacity polyester or bright high tenacity nylon. The range used to date goes from 400 denier weft up to 2000 denier in the form of a 2 fold

1000 denier polyester. The function of the weft in this tubular fabric is to give high resistance to stretch when the tube is under pressure. This is achieved by combining the number of threads per inch together with the denier or thickness of the yarn used. By using a high number of weft picks per inch (30 to 48) with the correct yarn it is possible to resist pressures of up to 300-500 lbs. per square inch comfortably. The choice of yarn for the weft will also govern both the resistance to strength and the elasticity of the webbing when in use under pressure.It is possible by this weaving application to make changes to suit any requirements called for.

Six examples based on the same basic nylon warp of 500 ends of 850 denier nylon are given below. The weft and picks per inch were changed to vary the resistance to internal pressures.

Sample 9-38 picks per inch 1000 terylene weft 1000 Terylene spool Sample 10-32 picks per inch 2/1000 terylene weft 2/100 spool Terylene Sample 11-32 picks per inch 1770 nylon B weft 940 spool nylon Sample 12-36 picks per inch 1770 nylon weft 940 spool nylon Sample 13-36 picks per inch 1770 nylon weft 1770 spool nylon Sample 11 10 picks per inch 940 nylon weft 2/940 Bt,nylon spool All samples were woven 3i" wide flat.

Tests with samples of 100% polyester yams have been encouraging, and two examples of such samples are as follows: Sample A 100% Polyester Warp-550 Decitex, 230 ends per inch Weft-8 ends 550 Decitex 30 picks per inch Sample B 100% Polyester Warp--550 Decitex-230 ends per inch Weft-6 ends 550 Decitex-34 picks per inch DECITEX IS A REGISTERED TRADE MARK When a tube assembly as described with reference to Figures 7 and 8 or Figures 9 of the drawings is used in a pinch valve, the outer sleeve 24 takes all of the stress created by the higher pressure in the tube assembly, and the valve casing is relatively free of such pressure, enabling a much lighter gauge valve casing to be used, which is desirable, and as the sleeve to the tube can be varied by replacing the sleeve. Furthermore, the pinching forces necessary to close the valve are much less than those required for pinching an equivalent high pressure flexible tube of conventional construction and embodying canvas in the tube wall thickness, and the sleeve is free, or substantially free of any axial stretching when in the pinched condition - as has been explained.

This tube assembly according to the invention could be used in the applications. For example in a peristakic pump.

As shown in Figures 2 and 5, it will be observed that the valve in which the tube assembly 10, 24 is located, comprises basically a pair of similar valve body halves 260, 280 which together define a T-shaped interior space with the tube assembly 10, 24 extending in the arms of this T-space and the valve plunger 300 being located in the leg of the T.

Where the leg meets the arms, the rounded end of plunger 300 can engage the tube assembly 10, 24 to close same. The valve shown in Figure 2 ob the drawings is operated simply by means of an operator's handle 320 and by turning this handle 320, plunger 300 is forced to move up or down in Figure 8 or 9. The lower limit of movement of the plunger 300 is illustrated in Figure 6 and it will be noticed in this position that one tubular member section is pressed into firm contact with the inside of the other section. Figure 5 shows how rhe valve body halves 260 and 280 can be pivoted apart about their axis of hinge pins 282 to enable the tube assembly 10 (24) to be removed for cleaning and, if necessary, replacement, and in fact Figure 2 shows the halves 260 and 280 fully open, the hinge pins being indicated by numeral 282.

The valve without the plunger could be used as a water pipe connection, and the tube assemblies could be fitted in pipelines to allow for moving of the valve plunger positions.

The assembly shown in Figure 8 and in the assembly shown in Figure 9 fitted in the valve casing as shown, in a similar manner, except that the casing is slightly modified. It may be desirable initially to treat the sleeve with a chemical or coating composition in order better to effect the permanent setting of the pleats with the subsequent application of heat and pressure.

WHAT I CLAIM IS:- 1. A fabric sleeve usable around a flexible tube to form a tubular assembly usable in a pinch valve, said sleeve having at least one permanent set pleat folded back onto the sleeve and extending circumferentially of the sleeve thereby to reduce the effective axial length of the sleeve at least over a circumferential portion of the sleeve, the arrangement being that the sleeve can be arranged around said

flexible tube to form a tube assembly for a pinch valve so that when such assembly is pinched the pleat unfolds allowing the sleeve or at least said sleeve portion to increase its axial length without the sleeve being stretched, or stretched to a significant degree, the permanent set of the pleat causing it to reform when the pinching effect is removed.
2. A sleeve according to Claim 1, wherein there are two of said pleats in the sleeve, said pleats being symmetrically arranged relative to a central radial plane of the sleeve whereat the pinching is to be applied.
3. A sleeve according to Claim 1 or 2, wherein the or each pleat tapers from a maximum axial width to zero in each direction from said maximum axial width.
4. A sleeve according to Claim 1 or 2, wherein the or each pleat is of constant width and extends completely round the sleeve.
5. A sleeve according to any of claims 1 to 4, wherein each end of the sleeve has a flange formation for co-operation with a flange formation on the flexible tube around which the sleeve is to be placed.
6. A sleeve according to any of claims 1 to 5, wherein the sleeve is woven from nylon warp yarns and polyester weft yarns, the weft yarns extending circumferentially of the sleeve.
7. A fabric sleeve substantially as hereinbefore described with reference to Figure 8 or Figure 9 of the accompanying drawings.
8. A tube assembly comprising a flexible tubular member having end flange formations and a reinforcing, pre-formed fabric sleeve according to any preceding claim lying on and separable from the outside of the tubular member and extending between the tubular member flange formations, the ends of said sleeve being turned outwardly so as to lie adjacent the respective tubular member flange formations so that outwardly turned ends of the sleeve and said respective tubular member end flange formations can be anchored one relative to another in the use of the assembly to keep the sleeve and tubular member ends relatively positionally fixed.
9. A tube assembly according to Claim 8, wherein the tubular member is of circular outer cross section over an axial region be- tween the ends thereof, and has internal opposing shoulders at said region which divide the internal tube section at the shoulders into a first portion and a second portion which includes the shoulders, the circumferential internal length of the first portion being equal to the circumferential internal length ob the second portion so that the tube can be pinched closed by moving the first portion into the second portion and over the shoulders, whilst the flexible tubular member with the sleeve thereon is held in a rigid tube matching the outside diameter of the flexible tubular member and sleeve.
10. A tube assembly according to Claim 9 wherein the section of the tubular member at said shoulders defines two spaced segments which contain the shoulders and two further opposite segments in which the tube wall thicknesses are constant and equal.
11. A tube assembly according to Claim 9 or 10, wherein the tube assembly is straight and internally, apart from the said shoulders, the flexible tube is of circular section.
12. A tube assembly according to Claims 9, 10 or 11 wherein the shoulders taper away to nothing in the axial directions away from the centre of the region.
13. A tube assembly substantially as hereinbefore described; with reference to Figure 8 or Figure 9 of the accompanying drawings.
14. A pinch valve including a valve casing defining a bore, a tube assembly according to Claim 9, or any preceding Claim when dependent upon Claim 9, said bore matching said tube assembly which is located in said bore, a pinching plunger means adapted to engage the tube assembly so that the tube assembly can be pinched closed by moving the first portion into the second portion and over the shoulders, whilst the tube assembly is held in said casing.