GB2295885A

GB2295885A - Ball valve

Info

Publication number: GB2295885A
Application number: GB9522825A
Authority: GB
Inventors: Erhard Pfannenschmidt
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-10
Filing date: 1995-11-07
Publication date: 1996-06-12
Anticipated expiration: 2015-11-07
Also published as: DE4444031C1; GB9522825D0; TW306964B; GB2295885B; FR2728044B1; FR2728044A1

Description

Ball valve 2295885 The invention refers to a ball valve according to the

generic term of patent claim 1.

In the case of so-called TOP ENTRY ball valves, the housing is sealed by means of a flange or a screw top for holding the plug of the cock in order to create an opening for installing the plug of the cock which also enables the plug of the cock and seals to be removed after such a ball valve has been welded in as part of a duct.

A ball valve has come to light from DE 39 14 327 which has a cover on the housing. The housing contains two lockable conduits running in parallel to which is assigned a rotating, hemispherical plug running on bearings in the housing. This closes the housing with the plug by means of the cover which is designed as the actuating mechanism for the plug. Sealing rings are fitted coaxially in extended recesses of the conduits; these are in the immediate area of the holes in the ball.

A ball valve has come to light from DE 94 08 156 in Mich a single-piece sealer forms a seal by resting on the walls of the cavity in the housing and which has a hemispherical recess for the plug of the valve as well as coaxial holes with coaxial connecting holes. The sealer is made from a suitable material and completely covers the cavity in the valve housing, so that the medium travelling through the valve cannot be held back in crevices or other dead spaces. This is further improved by the fact that the cover helps to press the sealer tightly into the cavity by means of preliminary tension at the plug of the cock. This prevents the product from entering the cavity between the cover and the plug, for example. A ball valve with this structure functions satisfactorily. However, N the seal be- 1 comes damaged, it is necessary to replace the complete cladding formed by the sealer. This involves not inconsiderable expense, particularly K the sealer is to be made from high-grade material.

For this reason the purpose of the invention is to create a ball valve which can be welded in place and which enables the plug of the cock and the sealant to be installed and removed, has no crevices or dead spaces where the product can become lodged, and can be manufactured with the minimum of expenditure on production and materials.

These requirements are met by the characteristics of patent claim 1.

The ball valve of the invention is provided with sealer inserts in appropriate recesses in the plug of the cock. These have a convex outer surface adapted to the spherical form of the plug. In the case of a continuous hole through the plug, for example, the recesses are offset at an angle of 900 to it. Depending on the ball valve version, i.e. whether a two-, three-, fouror five-way valve is to be provided, the recesses with the sealing inserts are arranged accordingly. This means that with appropriate rotational actuation, the plug of the sealing insert sufficiently covers an assigned connecting hole in the housing so as to achieve the sealing effect required.

The holder for the sealing inserts or sealing elements in the plug is designed so that no crevices are formed. The invention therefore produces a ball valve which is free of dead spaces. The material for the sealing inserts should be chosen according to requirements, i.e. the aggressiveness of the media or the temperatures. For example, metal sealing inserts can be fitted for operation at high temperatures.

The amount of material used for the sealing inserts is relatively small, which is particularly significant when expensive materials are used. The manufacturing process for the sealing elements is also relatively simple. Wearing parts can also be replaced when the mounting is welded on the connecting side.

2 The most advantageous shape for the surface area of the sealing element is orbicular, but it can also be polygonal. A press fit for an orbicular sealing element is preferential. When relaxed, the external surface of the sealing element can protrude radially beyond the contour of the plug in order to achieve an effective pressure and seal when closed.

In a further form of the invention the sealing elements have a dome shape on the underside. The dome shape allows the outer radial area of the sealing element to be pressed in, so that the sealing element forms a kind of spring which presses down on the connecting hole in the housing, creating an effective seal. Alternatively, a spring element can be fitted between the sealing element and the bottom of the recess, thereby providing the contact pressure described. Another form of the invention calls for a ring groove to be provided on the underside of the sealing element which contains an 0 ring. The 0 ring forms a spring. It is not required for sealing purposes.

Another form of the invention calls for the selector shaft to be surrounded by a sealing ring, one face of which is flush with the plug, whereby the selector shaft is pretensioned by means of a nut supported by the housing. This allows the hemispherical plug and the selector shaft seal to be pretensioned simultaneously from the outside. The ball valve can therefore function without requiring maintenance and adjusts itself automatically if a disk spring is placed between the nut and the housing.

In another form of the invention, the plug can be of cylindrical section which fits into a cylindrical socket of the housing and is flush with the cover. The cylindrical section seals off the housing from the cover without any cavities and also forms another bearing for the plug. In a further version of the invention, a fairlead bush, preferably made from a sealing material, can be pushed over the cylindrical section of the plug. This also forms a seal with the cover which, in one version of the invention, can also be provided with a sealing ring.

Appropriate non-stick material such as PTFE or the like is particularly effective in preventing a product from being carried over from the closed 3 position and becoming lodged between the metal components when the plug is opened.

The invention is explained in greater detail below by means of diagrams.

Fig. 1 shows a cross-section through a ball valve as per the invention in closed position.

Fig. 2 shows the ball valve as per figure 1 in open position.

Fig. 3 shows a top view of the ball valve as per figure 1, along line 3-3.

Fig. 4 shows a plug with a modified sealer insert.

Fig. 5 shows a cross-section through a ball valve as a three-way device with an L-shaped hole in the plug.

Fig. 6 shows a cross-section similar to fig. 5, but with a T-shaped hole in the plug.

Ball valve 10 shown in figures 1 to 3 has a single-piece housing, 12, with two coaxial connecting holes, 14 and 16. These open out into a cavity consisting of a hemispherical cavity section, 18, and a cylindrical cavity section, 20. The cavity of the housing, 12, contains a hemispherical plug, 22, with a hole through it, 24. When ball valve 10 is open, hole 24 is aligned with connecting holes 14 and 16 (fig. 2). When ball valve 10 is closed, hole 24 is offset from holes 14 and 16 by 900.

Plug 22 has a cylindrical section, 26, which fits into a cylindrical cavity, 20. A bush, 28, made from a suitable sealing material is pushed onto it.

A cover, 32, is screwed into an opening, 30, in the housing, 12. The flat underside of cylindrical section 26 of plug 22 is flush with this. The cover contains an 0 ring, 34, in a corresponding groove for sealing off the cover, 32, from the housing, 12.

4 A selector shaft, 36, forms a one-piece unit with the plug, 22. The shaft extends to the outside through an appropriate hole in the housing, 12. A first ring-shaped seal, 38, is located in an extension to the hole in the housing and works together with the selector shaft, 38, and the upper part of the plug, 22, and is correspondingly adapted to the spherical contour of the plug, 22. A second ring-shaped seal, 40, is seated in an extended section of the hole in the housing and protrudes slightly beyond this. Outside of the housing, 12, the selector shaft, 36, is enclosed by a pressure ring, 42, on which a disk spring is fitted. The disk spring supports the collar, 46, of a hood-like section, 48, of an actuating lever, 50, which is connected to the selector shaft by means of a nut, 52, which is screwed onto the top threaded section of selector shaft 36.

There are downward-pointing lugs, 54, 56, on the hood-like section, 48, which fit into the curved recesses, 58, 60, of the housing, 12. This restricts the rotation of the plug, 22.

The plug, 22, has recesses 62 and 64 on diametrically opposite sides which hold sealing elements 66 and 68. The axis of each recess is located on a radius of the hemisphere of plug 22. The external contour of sealing elements 66, 68, is adapted to that of plug 22, and when closed as per figure 1, the sealing elements 66 and 68 cover the ends of connecting holes 14 and 16, forming a seal. The underside of sealing elements 66 and 68 is dome-shaped in order to allow the outer radial areas to be pushed inwards into recesses 62 and 64. Sealing elements 66 and 68 therefore also form springs for applying pretension for the sealing effect described.

Nut 52 is used to pretension selector shaft 36 and plug 22 in order to achieve an effective seal with the plug, 22. in the housing, 12, without any dead spaces.

Plug 22a shown in figure 4 is similar to the one as per figures 1 and 2. Sealing elements 66a and 68a are flat-bottomed in correspondence to the base of recesses 62a and 64a. The underside of sealing elements 66a and 68a has a ring-shaped groove which contains an 0 ring. In figure 4, only 0 ring 70 of sealing element 68a can be seen. 0 ring 70 acts as a spring, pretensioning the sealing element in an outward direction.

Sealing elements 66 and 68 or 66a and 68a can be manufactured from a suitable material such as PTFE, PTFE compound, graphite, ceramics, metal, as well as malleable and elastic materials, depending on the media and temperature requirements.

Figure 5 shows a cross-section of a ball valve housing, 11, as per the invention, with a plug, 21, which has an L-shaped hole, 25. Accordingly, housing 11, in addition to the connecting holes, 13 and 17, which are arranged coaxially with each other, also has a connecting hole, 15a, running at right angles. Two sealing elements, 65 and 67, are accordingly offset at right angles in appropriate recesses of plug 21 in order to assure the functioning of the three-way valve.

In addition to connecting holes 14b and 16b in housing 12b, the version shown in figure 6 has a third connecting hole, 15b, at right angles to the aligned connecting holes 14b and 16b. Plug 22b has a T-shaped hole, 24b, likewise for producing a three-way valve. A single sealing element, 66b, is fitted into an appropriate recess in plug 22b. Otherwise, the ball valves shown in figures 5 and 6 function in the same way as the ball valve described above. For this reason, they will not be dealt with in further detail. In addition, the plug is similar in form to the one described above and is seated in the valve housing in the same way.

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Claims

CLAIMS:

Ball valve with a housing with connecting holes which has an opening to a cavity located at right angles to the connecting holes, a rotating hemispherical plug which is inserted through the opening into the cavity and which can be actuated by means of a sealed selector shaft running on bearings; sealant between the plug and the housing and a cover closing off the assembly opening - being characterised by the fact that the plug (22, 22a) has recesses (62, 64, 62a, 64a) corresponding to the number of connecting holes (14, 16) which can be aligned with these holes and whose surfaces are so dimensioned and arranged as to cover the connecting holes (14, 16) when aligned accordingly, and sealing elements (66, 68, 66a, 68a) accommodated in the recesses (62, 64, 62a, 64a) whose external side is adapted to the spherical form of the plug (22, 22a).
Ball valve according to claim 1, characterised by the fact that the surface of the sealing elements (66, 68, 66a, 68a) is orbicular or polygonal.
Ball valve according to claim 1 or 2, characterised by the fact that the underside of the sealing elements (66, 68) is dome-shaped.
Ball valve according to one of the claims 1 to 3, characterised by the fact that a spring element is fitted between the sealing element and the bottom of the recess.
Ball valve according to claim 4, characterised by the fact that the underside of the sealing elements (66a, 68a) have a ring-shaped groove containing an 0 ring (70).
6. Ball valve according to one of the claims 1 to 5, characterised by the fact that the selector shaft (36) is enclosed by a sealing ring (38, 42), one of whose faces is flush with the plug (22), and that the selector shaft (36) can be pretensioned by means of a nut (52) supported on the housing (12).
7 7. Ball valve according to claim 6, characterised by the fact that a disk spring (44) is fitted between the nut (52) and the housing (12).
8. Ball valve according to one of the claims 1 to 7, characterised by the fact that the plug (22) has a cylindrical section (26) which is seated in a corresponding cylindrical recess (20) of the housing (12) and is flush with the cover (32).
9. Ball valve according to claim 8, characterised by the fact that a sealing ring (34) is fitted in the cover (32).
10. Ball valve according to claim 8 or 9, characterised by the fact that a fairlead bush (28), preferably made from a sealing material, is fitted onto the cylindrical section (26).
11. A ball valve substantially as hereinbefore described with reference to the accompanying drawings.

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