WO1992012368A1

WO1992012368A1 - Spherical valve

Info

Publication number: WO1992012368A1
Application number: PCT/NL1991/000270
Authority: WO
Inventors: Johannes Dominicus SCHRÖER
Original assignee: Terlet N.V.
Priority date: 1990-12-28
Filing date: 1991-12-24
Publication date: 1992-07-23
Also published as: NL9002901A; PT99955A; IE914570A1; PT99955B; AU9145391A

Abstract

A spherical valve is provided with a valve body shaped as a spherical segment which is suspended rotatably in a valve housing according to a centre line of the sphere which is determined by the spherical closing surface of the spherical segment, which valve housing has a passageway which can be closed by means of the spherical segment, which passageway is delimited by a circular valve seating with a seal, which at least at its face which cooperates with the spherical segment is provided with a wear resistant layer which may be pressed onto the spherical segment, the spherical segment being rotatable between a closed position in which it sealingly rests against the seal, and an open position in which it is at least partly outside the passageway. The seal is a section which is expandable by means of an internal overpressure.

Description

Spherical valve

The object of the invention is a spherical valve provided with a valve body shaped as a spherical segment which is suspended rotatably in a valve housing according to a centre line of the sphere which is determined by the spherical closing surface of the spherical segment, which valve housing has a passage way which can be closed by means of the spherical segment, which passage way is delimited by a circular valve seating with a seal, which at least at its face which cooperates with the spherical segment is provided with a wear resistant layer which may be pressed onto the spherical segment, the spherical segment being rotatable between a closed position in which it sealingly rests against the seal, and an open position in which it is at least partly outside the passage way. A spherical valve of this kind is known from French patent FR-A- 2029915- The invention is related to a spherical valve of this kind as applied to mixing devices. In the case of mixing devices, the spherical valve is situated at the bottom of the mixing vessel which in general has the shape of an inverted cone. The spherical segment of the valve which constitutes the valve body should provide such a sealing with respect to the valve seating, that also in the case of relatively high loadings exerted by the mixing goods, a proper sealing is guaranteed. Furthermore, the sealing should be suitable for all kinds of different goods to be mixed, in particular wit.h respect to grain size, flowability, and viscosity.

The object of the invention is therefore to provide a spherical valve which is suitable for different kinds of mixing goods, which is able to withstand high loadings, and which in particular guarantees a perfect seal. This object is inchieved in that the seal is a section which is expandable by means of an internal overpressure. As soon as the valve segment is in its closed position, the profile is expanded by applying an internal overpressure, in such a way that a seal with respect to the surface of the spherical segment is obtained.

The advantage of such an expandable section is that also in case the surface of the spherical segment is polluted by grains which stick to said surface, such grains are enclosed by the seal and the proper sealing is still ensured.

In particular, the section is torus shaped, whereby the internal space of the profile is in communication with a source containing a fluid under overpressure. Preferably, at the face of the section facing away from the surface of the spherical segment, it is connected to a line which is also connected to the fluid source.

In order to ensure a good sealing action, the profile, at least at its face facing the surface of the spherical segment, is grooved in a longitudinal direction.

According to a preferred embodiment, the valve seating has a groove which runs around the passage way, whereby the cross-section of the groove corresponds essentially to that of the section, which groove in the direction perpendicular with respect to the surface of the sphere which is determined by the spherical segment is larger than the dimension of the non-expanded section in that direction. Thereby, the groove at its side facing the passage way may be provided with a groove wall which is extended in the direction of the sphere determined by the sphere segment, in order to provide for a scraping edge for scraping and cleaning the surface of the spherical segment.

The invention will be explained further with reference to the embodiments shown in the drawings.

Figure 1 shows a view in section a first embodiment of a spherical .valve according to the invention.

Figure 2 shows a part of figure 1 on a larger scale, of the sealing of the valve.

Figure 3 shows a second embodiment.

The valve shown in figure 1 has a valve housing one as well as a valve member 2. This valve member encompasses a spherical segment 3. which by means of legs is supported in bearings - These bearings are aligned on both sides of the passage way through the valve. This passage way of the valve is determined by the opening in both flanges 6 and 7, which are welded at opposite sides of the edge of the spherically shaped housing.

The bearings 5 each contain a cap 9. which is rotatable around stubs 10. Between each cap 9 and stub 10 there is a bearing 11. By means of the gaskets 12 the caps 9 are perfectly sealed with respect to the stubs 10. By means of the gaskets 13 the stubs 10 are sealed with respect to the housing edge of the valve.

One of the stubs 10 may be hollow, such as to contain a drive axle 1 . for moving the valve between its different positions.

As shown on a larger scale on figure 2. the spherical segment 3 can cooperate with a sealing ring which is indicated with 16. This sealing ring encompasses an envelope of wear resistant material 17, which at the side facing the spherical segment is filled with an elastically compressable material 18. Furthermore, this envelope contains a relatively hard material 19. The valve housing determines a supporting edge 20 for the sealing ring 16. Also, a pressure ring 21 is provided, which by means of bolts (not shown) may be clamped onto the flange 6.

Upon applying the pressure ring 21 onto the sealing ring 16 the relatively hard material 17 is compressed between the pressure ring 21 and the supporting edge 20. In doing so this relatively hard material 19 deforms in radial direction and obtains somewhat the shape of a curved edge 22, as shown in figure 2. This means that the elastically compressible material 18 is under pre-tension. As soon as the valve is closed, the spherical segment 3 comes to rest against the sealing ring 16. Thereby, both the envelope 17 as well as the pre-tensioned elastically compressible material 18 are deformed. In such a way a good sealing of the seal ring 16 with respect to the spherical segment 3 is ensured.

As shown furthermore in figures 1 and 2, the pressure ring has a -scraping edge 23. This scraping edge is at such a position that upon opening or closing of the valve, the surface of the spherical segment 3 closely moves past said edge. In such a way, the scraping edge may push away any pollutions which adhere to the surface of this spherical segment 3, before touching the sealing ring 16. This has a favourable influence on the usefull life of the sealing ring.

The envelope 17 and the sealing ring 16 may consist of teflon. Furthermore the surface of spherical segment 3 may be smooth, in such a way that hardly or no pollutions adhere to said surface.

In the second embodiment shown in figure 3_t again a spherical segment 3 is applied as a valve body. It is supported in housing 1 by means of legs . . The sealing ring in this case consists of an expandable section 2 . of elastic material. At its face facing the segment 3. it may be provided with longitudinal grooves 25 so as to guarantee a proper sealing. The section 2 . runs around the passage way of the valve housing, and thereby has the shape of a torus. It is in communication with at least one pressure line 26, which is connected to a source with a pressurized medium. Preferably, there are several pressure lines 26, connected to the section 24. Said section 24 is supported in a valve seating 27 equipped with a groove 28. The cross-section of said groove 28 largely corresponds to the cross-section of section 24. However, the dimension of groove 28 perpendicular with respect to the spherical surface of segment 3 is larger than the corresponding dimension of section 24 in non-expanded condition.

With the segment 3 in closed position, the section 24 is pressurized. Thereby it expands, comes to lie against the segment 3 as indicated at 30, and ensures a proper sealing. Before opening the valve, the section 24 is de-pressurized so that it may return to the retracted position.

The valve seating 27 is provided with a scraping edge 29.

Claims

C L A I M S

1. Spherical valve provided with a valve body shaped as a spherical segment which is suspended rotatably in a valve housing according to a centre line of the sphere which is determined by the spherical closing surface of the spherical segment, which valve housing has a passage way which can be closed by means of the spherical segment, which passage way is delimited by a circular valve seating with a seal, which at least at its face which cooperates with the spherical segment is provided with a wear resistant layer which may be pressed onto the spherical segment, the spherical segment being rotatable between a closed position in which it sealingly rests against the seal, and an open position in which it is at least partly outside the passage way characterized in that the seal is a section which is expandable by means of an internal overpressure.

2. Spherical valve according to claim 1, in which the section is torus shaped, and in which the internal space of the profile is in communication with a source containing a fluid under overpressure.

3« Spherical valve according to claim 1, in which the face of the section facing away from the surface of the spherical segment is connected to a line which is also connected to the fluid source.

4. Spherical valve according to claim 3» in which the line is provided with a two way valve for selectively connecting the internal space of the torus shaped profile with the fluid source or the surrounding atmosphere.

5. Spherical valve according to one of the preceding claims in which the profile, at least at its face facing the surface of the spherical segment has the shape of a strip, which is grooved in longitudinal direction.

6. Spherical valve according to claim 5. in which the section has a retangular or square cross-section.

7. Spherical valve according to one of the preceding claims, in which the valve seating has a groove which runs around the passage way, the cross-section of the groove corresponding essentially to that of the section, which groove in the direction perpendicular with respect to the surface of the sphere which is determined by the spherical segment is larger than the dimension of the non-expanded section in that direction.

8. Spherical valve according to claim 7, in which the grooves at its side facing the passage way has a groove wall which is extended in the direction of the sphere determined by the sphere segment, in order to obtain a scraping edge for scraping and cleaning the surface of the spherical segment.