GB2122128A - Valve control mechanism - Google Patents

Abstract

A valve control mechanism comprises an enlarged diameter portion (7) in a sealed fluid-carrying duct (8). The portion (7) contains a magnetised (10) valve member (9) carrying an external screw-thread (17) which co-operates with a screw- thread (13) formed internally of the portion (7). The valve member (9) has a valve surface (14) at one end which co-operates with a valve seat (15) at one end of the portion (7), a discontinuity (16) or other passage being formed in the valve member (9) to prevent it from otherwise impeding fluid flow. A ring-shaped magnetic adjustment member formed from two interconnected identical half-rings (1, 2) is made of a synthetic plastics material, such as nylon, by conventional injection moulding and contains a particulate magnetic filler, such as ferrite powder, magnetised to produce radially inwardly directed N and S poles. When the member (1, 2) is rotated around the portion (7), the magnetised valve member (9) revolves and is moved axially by co- operation of the screw-threads (13, 17). <IMAGE>

Description

SPECIFICATION Valve control mechanism This invention relates to the remote control of valve members of the kind in which there is no physical connection between the valve member whose position is controllable and an adjustment member governing that position.

It is often necessary to be able to control the rate of flow of a fluid through a closed duct and it is frequently important that there should be no possibility of the fluid being able to escape at the control location and/or of it being contaminated by the ingress of air or some other surrounding liquid or gaseous environment. This problem has been overcome, to a large extent, by building into a tubular duct, for the passage of such a fluid, a tapering or other valve seat and providing, internally of the duct, a valve member which has a tapering or other surface arranged to co-operate with said seat, the valve member being axially displaceable towards and away from the valve seat by the co-operation of matching screw threads formed around part of the valve member and internally of the duct itself or internally of a ring secured in position inside the duct.The rate of flow of fluid through the duct can thus be controlled by rotating the valve member in the duct so that the co-operation of the screwthreads causes consequential axial movement of the tapering or other valve surface of the valve member either towards, or away from, the fixed valve seat depending upon the direction of rotation employed.

The drive to the rotatable valve member is established, to govern the rate of flow of a fluid through the duct, by co-operating magnets, the valve member itself carrying magnets which establish radial poles and an adjustable member that surrounds the exterior of the duct similarly carrying magnets which establish radially inwardly directed poles. The duct itself is, of course, of nonmagnetic material and upon manually or otherwise rotating the adjustment member, which is conveniently ring-shaped, around the duct, the internally disposed valve member will similarly rotate and more axially to open or close the valve to the desired extent.

The magnetic adjustment members comprise, at present, expensive samarium-cobalt magnets embedded in a carrier material, which is conveniently a synthetic plastics material, since a very strong magnetic field is naturally desirable to ensure reliable co-operation between the adjustment members and the valve members. The production of such adjustment members is expensive both as regards the magnetic material involved and the machining techniques that are required.The use of so-called "ceramic" magnets has been tried as an alternative to samariumcobalt magnets, forming the "ceramic" magnets as rings, subsequently cutting them into halves and embedding those halves in a synthetic plastics or other carrier (except for their concave inner surfaces), but the cost is only marginally reduced since cutting and labour-intensive insert-loading (embedding or overmoulding) steps are still required.

It is an object of the present invention to provide valve control mechanism in which the cost of producing the magnetic parts thereof is very significantly reduced, as compared with known constructions, without any loss in operating efficiency and, accordingly there is provided a method of forming a magnetic adjustment member for use in a valve control mechanism, wherein the method comprises forming said member by injection moulding from a synthetic plastics material carrying a particulate magnetic filler.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:~ Figure 1 is a perspective view of the two halves of a ring-shaped magnetic adjustment member constructed in accordance with the invention, Figure 2 is a view of the adjustment member of Figure 1 as seen in an axial direction, Figure 3 corresponds to Figure 2 but illustrates an alternative construction, and Figure 4 is an enlarged and somewhat diagrammatic view of a fluid flow valve comprising a magnetic adjustment member in accordance with the invention.

Referring firstly to Figures 1 and 2 of the accompanying drawings, the magnetic adjustment member that is illustrated therein is formed by juxtaposing two identical half members 1 and 2 each of which has the shape of a half ring subtending marginally less than 1 800 at its centre of curvature, each half member 1 and 2, in the example that is being described, having an internal diameter of 1 1 millimetres, an external diameter of 19 millimetres and an axial length (thickness) of 12 millimetres.

The two half members 1 and 2 are formed, in accordance with the invention, by the injection moulding, by a conventional technique, of a synthetic plastics material, such as the polyamide material known as "nylon", that material carrying a particulate magnetic filler which may advantageously be powdered ferrite. After formation by injection moulding, each identical half member 1 and 2 is magnetised in such a way as to give it one north pole and one south pole orientated radially inwardly at locations which are 900 removed from one another around the centre of curvature of the half member concerned, each pole being substantially 450 removed around the same centre of curvature form one end of the half member.Thus, when the two half members 1 and 2 are juxtaposed as shown in Figure 2 of the drawings, the complete magnetic adjustment member comprises four radially inwardly directed north and south poles which are alternate considered rotationally around the centre of curvature of the complete member and that are spaced apart from one another at substantially 900 intervals around the same axis.

It can be seen in Figures 1 and 2 of the drawings that, at its opposite ends, each half member 1 and 2 is formed with corresponding grooves 3 which grooves 3 extend throughout the axial length (thickness) of each half member 1 and 2 and are key-hole shaped. A flexible synthetic plastics, rubber or synthetic rubber hinge member 4 (Figure 2) is shaped so as to be capable of joining the two half members 1 and 2 together by insertion lengthwise into a facing pair of the grooves 3. This will, it will be appreciated, enable the two half members 1 and 2 to be turned relative to one another by flexing of the hinge member 4 to a sufficient extent to enable them to be passed around the valve portion 7 of a duct (Figure 4) and then closed together to embrace that valve portion 7.When so closed, a second similar hinge member 4 may be entered lengthwise into the two grooves 3 that are shown at the foot of Figure 2 of the drawings to maintain the complete magnetic adjustment member in a closed condition around the valve portion 7 of the duct as long as may be necessary. The frictional engagement of the hinge members 4 in the grooves 3 is sufficient to prevent any unwanted axial displacement of one half member 1 or 2 relative to the other.

Figure 3 of the drawings illustrates an alternative construction which is identical to that of Figures 1 and 2 except that separate hinge members 4 are not provided nor necessary. In the embodiment of Figure 3, each of the identical half members 1 and 2 is formed at one end with a groove 5 and at the opposite end with a matching projection 6. Each groove 5 is more or less keyhole shaped and each projection 6 is of a matching shape so that the two half members 1 and 2 can only be engaged with one another, or be separated from one another, by relative movements in an axial direction which is perpendicular to the plane of Figure 3 of the drawings but not by a movement that is in a direction parallel to that plane.The projections 6 preferably fit in the grooves 5 sufficiently tightly to ensure that the two half members 1 and 2 are not loosely coupled together and will not move axially relative to one another until a significant force intended to cause such movement is applied to them.

It is appreciated, of course, that the magnetic strength of a magnet which comprises a synthetic plastics material filled with ferrite powder or other particulate magnetic material is not as great as that of a samarium-cobalt magnet or a "ceramic" magnet. However, it will be appreciated that the whole of the magnetic adjustment member that comprises the two half members 1 and 2 is magnetised whereas, in the cases of the known constructions that are referred to above, only the magnets forming parts thereof exhibit any magnetic activity whilst the plastics materials in which those magnets are embedded are magnetically inert.It has been found that a magnetic adjustment member constructed in accordance with the invention need not have any significantly greater axial length than does a magnetic adjustment member of one of the known constructions just mentioned bearing this advantage in mind. The principal advantage of forming the magnetic adjustment members in the manner that has been described is that a simple and conventional injection moulding technique can be employed, there being no necessity for any cutting, insert-loading, embedding or over moulding operations. A considerable reduction in costs results since the production machines employed can make a much larger number of magnetic adjustment members per unit time and can easily be controlled in such a way as to complete the whole process in an automatic, or at least semi-automatic, manner.

Referring now to Figure 4 of the drawings, a magnetic adjustment member constructed in accordance with the invention is used in the manner briefly described in the opening paragraph of this document, being disposed in surrounding relationship with the enlarged diameter control location portion 7 of a fluid-carrying duct 8. In the case of the particular embodiment that is being described, the enlarged portion 7 of the duct 8 has an external diameter of fractionally less than 1 1 millimetres whereas the duct 8, proper, may have an external diameter of only about 3 millimetres.A valve member 9 which is located internally of the control location portion of the duct 8 comprises magnets 10 arranged to co-operate with the radially inwardly directed magnetic poles of the adjustment member and these valve member magnets 10 may be samarium-cobalt magnets, "ceramic" magnets or may be formed in substantially the same way as the adjustment member by injection moulding a synthetic plastics material carrying ferrite powder or some other particulate magnetic filler and subsequently magnetising this part of the valve member 10 so as to give it radially outwardly directed north and south poles which will match the positions of the radially inwardly directed magnetic poles of the surrounding, in use, adjustment member.Upon manually or otherwise rotating the adjustment member 1/2 (shown only in broken lines in Figure 4) around the control location portion 7 of the duct at a position between a sealed end cap 11 of said portion 7 and a fixed external flange 12 thereof, the internally disposed valve member 9 will rotate with the adjustment member 1/2 and, because of the co-operation of a screwthread 17 on its external surface with a screwthread 13 on the internal surface of the enlarged portion 7 of the duct 8 or the internal surface of a ring fixed in the portion 7, the valve member 9 will move axially in said portion 7 of the duct so that a tapered or other valve surface 14 which it carries will move towards, or away from, a tapered or other co-operating valve seat 1 5 at or near to one end of said control location portion 7 of the duct 8. If the duct 8 is formed from a transparent material (as illustrated), the axial movement of the valve member 9 can be observed visually but this is, of course, not necessary and reference to a measuring instrument showing the rate of flow of fluid through the duct 8 will usually be obtainable as an alternative, or in addition. It is noted that the particular dimensions of the magnetic adjustment member 1/2 and of the co-operating control location portion 7 of the duct 8 with which that member 1/2 is tq be used, and of the duct 8 itself are given purely by way of example, the invention being equally applicable to installations of both smaller and large sizes. It is by no means essential that magnetic adjustment members constructed in accordance with the invention should be magnetised so as to have a total of four radially inwardly directed magnetic poles.Other numbers of poles are equally possible such as, purely for example, twelve poles spaced apart from one another at substantially 300 intervals around the longitudinal axis/centre of curvature of the adjustment member, any one of three sets of four of these poles being arranged, in use, to co-operate with four magnets, or magnetic poles, of the associated valve member 9 which are spaced apart from one another at 900 intervals around the longitudinal axis of that valve member.

The construction of the axially movable valve members 9 with which the magnetic adjustment members 1/2 co-operate is such that the flow of fluid through the duct 8 can be stopped, or throttled to a desired extent, only by co-operation between the valve seat 15 in the control location portion 7 of the duct 8 and the valve surface 14 of the valve member 9. In other words, the body of the valve member 9 itself does not obstruct the flow of fluid through the enlarged control location portion 7 of the duct. This is accomplished by, for example, forming discontinuities 16 in the screw threaded external surface 1 7 of the valve member 9 through which discontinuities 16 the fluid can pass.

Claims (15)

1. A method of forming a magnetic adjustment member for use in a valve control mechanism, wherein the method comprises forming said member by injection moulding from a synthetic plastics material carrying a particulate magnetic filler.

2. A method as claimed in claim 1, wherein the synthetic plastics material is a polyamide material.

3. A method as claimed in claim 1 or 2, wherein the particulate magnetic filler is powdered ferrite.

4. A method as claimed in any preceding claim, wherein said member is ring-shaped.

5. A method as claimed in claim 4, wherein said member is formed as two separate half rings.

6. A method as claimed in claim 5, wherein said half rings are identical or substantially identical.

7. A method as claimed in claim 5 or 6, wherein separate flexible hinge members are employed to connect the two half rings releasably together.

8. A method as claimed in claim 5 or 6, wherein the two half rings integrally incorporate hinge members to connect the two half rings releasably together.

9. A method as claimed in claim 7 or 8, wherein the two half rings and their hinge members are so constructed and arranged that they can be connected releasably together, when separated, by moving them relative to one another in a direction parallel to their central axes of curvature.

10. A method as claimed in any one of claims 7 to 9, wherein each half ring is formed at at least one end with a substantially key-hole shaped slot for co-operation with a hinge member.

11. A method as claimed in claim 4 or in any one of claims 5 to 10 when read as appendant to claim 4, wherein the ring-shaped member is magnetised to give it four substantially radially inwardly directed poles which poles are alternately "North", "South" and spaced apart from one another at substantially 900 intervals considered rotationally around the central axis of the member.

12. A magnetic adjustment member when formed by a method as claimed in any preceding claim.

13. A magnetic adjustment member substantially as hereinbefore described with reference to Figure 1 and 2 or Figure 3 of the accompanying drawings.

14. A valve control mechanism of the kind set forth and incorporating a magnetic adjustment member as claimed in claim 12 or 13, wherein said mechanism comprises an enlarged diameter portion or chamber formed in a sealed fluidcarrying duct, said chamber containing a magnetised valve member carrying a screwthread arranged to co-operate with a screw-thread disposed internally of the chamber whereby, upon moving the adjustment member rotationally around the exterior of the chamber, the magnetised valve member will rotate and be moved axially in the chamber by co-operation of said screw-threads to cause said valve member to tend to open or close a fluid path through the chamber.

15. A valve control mechanism as claimed in claim 14, wherein said valve member co-operates with a valve seat at only substantially one end of the chamber, said valve member itself being formed with at least one fluid passage therethrough or therearound to prevent the valve member from impeding fluid flow except by co-operation with said seat.

1 6. A valve control mechanism of the kind set forth substantially as hereinbefore described with reference to Figures 1, 2 and 4 or Figures 3 and 4 of the accompanying drawings.