GB2091387A - Fluid valves - Google Patents

Abstract

A fluid valve 11, suitable for use in fluid-pressure-operable systems, includes housing means 15/16, a valve element 31 and a hollow member 37, 38 which is adapted detachably to be secured in the housing means. The hollow member has a first seating 44, 46 formed at one end portion thereof and a second seating 41, 42 formed at another portion thereof. The second seating is caused, when the hollow member is so secured in the housing means, directly and sealingly to engage an associated surface 35, 36 formed in the housing means. The valve element is axially movable into direct sealing engagement with the first seating. <IMAGE>

Description

SPECIFICATION Fluid valves This invention relates to fluid valves suitable for use in fluid-pressure-operable systems and having a valve element which is automatically closable, for example under back-pressure applied thereto, onto an associated valve setting. Such valves form non-return check valves, while others, in which two of said valve seatings are provided and in which the valve element closes onto either the one seating or alternatively onto the other seating depending upon which end of the element is subjected to the higher fluid pressure, form shuttle valves.

Hitherto it has been the practice to include in such fluid valves at least one sealing ring, for example of elastomeric material, between components thereof for preventing undesired leakage of fluid.

This has proved somewhat costly and also inconvenient due to the need at desired intervals during the working life of the valve for the replacement of such sealing rings. Also during assembly of the valve components such sealing rings have sometimes been changed and/or partially displaced resulting in immediate or eventual leakage of fluid taking place.

The invention as claimed is intended to provide a remedy. It solves the problem of how to design a fluid valve which is of relatively simple and compact construction and in which no sealing rings are required.

According to the invention a fluid valve, suitable for use in fluid-pressure-operable systems, includes housing means, a valve element and a hollow member which is adapted detachably to be secured in said housing means, which has a first seating formed at one end portion thereof and which has a second seating formed at another portion thereof, said second seating being caused, when said hollow member is so secured in said housing means, directly and sealingly to engage an associated surface formed in said housing means, and said valve element being axially movable into direct sealing engagement with said first seating.

The housing means may comprise a valve casing and a sleeve member which is sealingly retained in a bore of that casing, said sleeve member housing said valve element and receiving said hollow member. In this case the two end portions of said sleeve member may be caused sealingly to engage the wall of said bore by suitably expanding them into fluid-tight and mechanical interlocking engagement therewith.

Preferably, the hollow member is screwthreadedly engaged with said sleeve member.

Further said second seating and said associated surface may be of complementary frusto-conical shape.

Alternatively, said second seating and said associated surface may be so shaped as when engaged to have line contact the one with the other.

An annular chamber may be formed immediately inwardly of said second seating and between said hollow member and said sleeve member, fluid pressure gaining access to that chamber serving to assist in the sealing of said sleeve member with respect to said wall of said bore.

The fluid valve may include two of said hollow members axially-spaced one from another with their said first seatings disposed facing each other, and said valve element which is disposed between those seatings having end portions of similar shape, whereby when one of those end portions is in operable engagement with its adjacent said first seating, the other of those end portions is spaced from its adjacent said first seating, and vice versa, such construction thereby forming a shuttle valve.

The advantages offered by the invention are mainly that an inexpensive fluid valve construction is provided which requires no sealing rings, with consequently less maintenance in service, and which affords adequate sealing during operation.

Two ways of carrying out the invention are described in detail below with reference to the accompanying drawings which illustrate only two specific embodiments, in which: Figure 1 is a cross-sectional side elevation of a fluid valve in accordance with the first embodiment, and, Figure 2 is a cross-sectional side elevation of the right-hand portion of a fluid valve in accordance with the second embodiment.

Referring to Figure 1 of the drawings the fluid valve shown is in the form of a shuttle valve 11 connected between three hydraulic lines 12, 13, 14 which for example form part of an hydraulic control circuit for a self-advancing roof support system disposed along the working face in a mine.

The housing means of the shuttle valve comprises a metallic casing 1 5 and a metallic sleeve member 1 6 disposed within the casing. On its outer surface the sleeve member is at each end portion provided with a series of annular grooves 1 7, 1 8 of V-shaped cross-section.

In order to secure the sleeve member 1 6 in the bore 19 of the casing a plug member (not shown) is driven by suitable means into each end portion of the sleeve member so as to expand the end portion into sealing engagement with the bore 19, the crests 20, 21 formed between the grooves biting into the surface of the bore to effect fluidtight engagement and mechanical interlocking between each end portion of the sleeve member and the casing.

Each plug member is then removed from the respective end portion of the sleeve member by suitable means and the energy stored in those end portions as a result of their expansion is adequate to maintain the sleeve member in permanent sealing engagement with the bore 1 9.

The sleeve member is provided with an annular recess 22 disposed centrally thereof, and radial ports 23 place this recess in communication with the interior 24 of the sleeve member. These ports align with a port 25 formed in the casing which communicates with the line 14.

The interior 24 of the sleeve member is screwthreaded at 26, 27 and is stepped down in diameter at 28, 29 to form a central bore portion 30 which houses an axially-slidable valve element 31 of acetal resin material, the main part 32 of which is of generally triangular cross-section. The two end portions 33, 34 of element 31 are of frusto-conical shape and engageable with respective first seatings later described.

The interior 24 of the sleeve member is provided with frusto-conical shoulders at 35, 36.

Hollow metallic members 37, 38 having externally-threaded portions 39, 40 and frustoconical shoulders 41,42, forming respective second seatings, are introduced into the end portions of the sleeve member 1 6, being screwed together at 26, 39; 27, 40 until the frusto-conical second seating surfaces of the shoulders 41, 42 engage the associated and complementary frustoconical surfaces of the shoulders 35,36. These engaging surfaces are sufficiently accurately produced as to provide reliable fluid sealing.

At its right-hand end in the drawing the stepped bore 43 of the hollow member 37 provides one said first seating which is of frustoconical form as shown at 44, while at its left-hand end in the drawing the stepped bore 45 of the hollow member 38 provides another said first seating which is of frusto-conical form as shown at 46. The end portion 33 of the element 31 is directly co-operable with the seating 44, and the end portion 34 of the element 31, which is oF similar shape to the end portion 33, is directly cooperable with the seating 46.

The seatings 44, 46 are so axially spaced apart and the element 31 is of such axial length that when the element is closed onto the seating 44 it is sufficiently displaced from the seating 46 that full fluid flow can occur from the line 13 into the line 14. Alternatively when the element 31 is closed onto the seating 46 it is sufficiently displaced from the seating 44 that full fluid flow can occur from the line 12 into the line 14.

Thus when, during operation of the associated system, a higher fluid pressure is subsisting in the line 13 than in the line 12, the element 31 is held firmly on the seating 44 in the manner shown in the drawing under the pressure differential acting upon it so that whilst fluid, for example hydraulic liquid, can pass freely from the line 13 into the line 14 no flow can take place from the line 12 into the line 14.

If the operation of the system is so changed that a fluid pressure subsists in the line 12 which is higher than that in the line 13, then the element 31 is shuttled to the right in the drawing so that it closes onto the seating 46, thus preventing flow of fluid from the line 13 into the line 14, and simultaneously places the line 12 in communication with the line 14.

By the construction above described no fluid sealing rings, such as for example elastomeric seals of circular cross-section, are required to be positioned between the components of the valve assembly. The sealing instead provided is effected entirely by direct metal-to-metal engagement of the crests 20/21 at the end portions of the sleeve member 1 6 with the bore 19, by direct engagement of the element 31 with either the seating 44 or the seating 46, and by direct metalto-metal engagement of the accurately produced frusto-conical surfaces 35, 41; 36, 42. Such direct engagement is intended to withstand relatively high fluid pressures and thereby provide high resistance to fluid leakage.

The hollow members 37, 38 are provided with means (not shown) which readily will accept a conventional tool, for example a screwdriver or a socket key, by which these members can quickly be unscrewed from the casing 15, facilitating ready servicing in the field. Such servicing may require the removal of the hollow members and their renovation, particularly in the region of their seatings, as well as the removal and renovation of the element 31 itself. Alternatively it may be necessary to replace any one or more of these items. However whatever is necessary to restore the valve as nearly as possible to its original condition will be achieved rapidly.

Referring now to Figure 2 of the drawings, both of the metallic hollow members of the shuttle valve, one only of which is shown at 51, are of different shape from those of the first embodiment in that each is stepped down at frusto-conical portion 52 from cylindrical surface 53 to cylindrical surface 54. A V-shaped groove 55 is formed beyond the surface 54 and adjacent the externally screw-threaded portion 56 of the member 51.

The metallic sleeve member 57 is similar to that of the first embodiment and is provided with an internally screw-threaded portion 58 near each end for receiving the screw-threaded portion 56 of the respective member 51. However, the bore 59 of the sleeve member is so stepped up in diameter at 60 that an annulus 61 is formed between the cylindrical surface 54 of each hollow member 51 and the respective inner cylindrical surface 62 of the sleeve member. Each surface 62 merges into a frusto-conical surface 63 which extends to the respective free end of the sleeve member. The annulus 61 is directly open to the V-shaped groove 55.

As in the first embodiment a valve element 64 of acetal resin material is provided and is shown with one of its frusto-conical end portions 65 in engagement with the first seating 66. As also shown, the second seating 67 has line contact with the respective associated, frusto-conical, surface 63.

The construction of the second embodiment and in particular the position of the second seating 67 are such that an increase in fluid pressure gaining access to the respective annulus 61 increases the sealing effect at the crests 68 which bite into the surface of the bore 69, resulting in a degree of pressure compensation for the seal.

Although in the embodiments above described with reference to the drawings the fluid valves described are in the form of shuttle valves, in other embodiments they may comprise non-return or check valves. In this case only one of said hollow members is provided for each valve, this having one frusto-conical end portion which is operably associated with a valve seating formed in the hollow member. Here again no fluid sealing rings are required to be positioned between the components of the valve, the sealing being effected by direct engagement of the components in the manner of the embodiments abovedescribed with reference to the drawings.

The invention is not limited to the provision of a valve element made in the material disclosed in the embodiments above-described with reference to the drawings, as in other embodiments other suitable non-metallic or alternatively metallic materials may instead be used for that element.

Although in the embodiments above-described with reference to the drawings said second seating of each hollow member comprises a shoulder of frusto-conical shape which engages an associated surface formed on the interior of the housing means, in alternative embodiments of the invention the externally screw-threaded portion of each said hollow member is of tapered form and is engageable with an internally screw-threaded part of said housing means which is of parallel form, the said second seating then being effectively formed by that portion of said hollow member which, on screwing of that hollow member into said housing means, comes into interfering and thus direct sealing engagement with the outer end of said internally screw-threaded part.

Claims (10)

1. A fluid valve, suitable for use in fluidpressure-operable systems, including housing means, a valve element and a hollow member which is adapted detachably to be secured in said housing means, which has a first seating formed at one end portion thereof and which has a second seating formed at another portion thereof, said second seating being caused, when said hollow member is so secured in said housing means, directly and sealingly to engage an associated surface formed in said housing means, and said valve element being axially movable into direct sealing engagement with said first seating.

2. A valve as claimed in claim 1, wherein said housing means comprises a valve casing and a sleeve member which is sealingly retained in a bore of that casing, said sleeve member housing said valve element and receiving said hollow member.

3. A valve as claimed in claim 2, wherein the two end portions of said sleeve member are caused sealingly to engage the wall of said bore by suitably expanding them into fluid-tight and mechanical interlocking engagement therewith.

4. A valve as claimed in either claim 2 or claim 3, wherein said hollow member is screwthreadedly engaged with said sleeve member.

5. A valve as claimed in any one of the preceding claims, wherein said second seating and said associated surface are of complementary frusto-conical shape.

6. A valve as claimed in any one of claims 3 to 4, wherein said second seating and said associated surface are so shaped as when engaged to have line contact the one with the other.

7. A valve as claimed in claim 6, wherein an annular chamber is formed immediately inwardiy of said second seating and between said hollow member and said sleeve member, fluid pressure gaining access to that chamber serving to assist in the sealing of said sleeve member with respect to said wall of said bore.

8. A valve as claimed in any one of the preceding claims and including two of said hollow members, wherein said hollow members are axially-spaced one from another with their said first seatings disposed facing each other, and said valve element which is disposed between those seatings has end portions of similar shape, whereby when one of those end portions is in operable engagement with its adjacent said first seating, the other of those end portions is spaced from its adjacent said first seating, and vice versa.

9. A fluid valve substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

10. A fluid valve substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.