GB2075638A - Rotary valve - Google Patents

Abstract

A rotary valve comprises seals which can be relieved at the actuating operation, the seals being in the form of loosely inserted sealing rings (13, 14) being on either side of a shut-off valve member (12) against mutually converging inclined surfaces (25, 26) forming a wedge-shaped zone, of wedge discs (15, 16) which bear against mutually parallel contact surfaces (18, 19) of a valve casing (11). The sealing rings (13, 14) can, as a consequence of a common displacement with the valve member (12) into the wedge-shaped zone, be stressed between these inclined surfaces (25, 26) and the valve member. The wedge discs (15, 16) are held against the contact surfaces (18, 19) of the valve casing by at least one stressing element (31) acting axially in their peripheral region. <IMAGE>

Description

SPECIFICATION Rotary valve The present invention relates to a rotary valve.

A rotary valve is described in DE-PS 22 02 097, in which wedge discs are seated in cylindrical recesses in a valve casing and bear against housing surfaces which bound the countersunk recesses. The contact surfaces of the wedge discs must seal against the casing surfaces which support the discs. When a gaseous or liquid medium to be conducted through the valve includes solid particles, it can happen at the actuation operation, in which the clamping of associated sealing rings and of the wedge discs between the casing surfaces that support the latter and a shut-off valve member is relieved, that such solid particles penetrate between the afore-mentioned casing surfaces and the contact surfaces of the wedge discs corresponding thereto.On further clamping after the actuation operation, lack of sealing can occur because a sealing contact of the contact surfaces of the wedge discs against the casing surfaces that support the latter is no longer provided.

There is accordingly a need for a rotary valve in which any risk of leakage as a consequence of solid particles penetrating between the contact surfaces of wedge elements and the casing surfaces that support the latter is eliminated or at least substantially reduced.

According to the present invention there is provided a rotary valve comprising a casing defining a valve chamber with two mutually parallel wall surface portions, two wedge elements each bearing against a respective one of the wall surface portions, mutually facing surface portions of the elements so converging towards each other as to define a generally wedge-shaped zone between the elements, a rotary valve member arranged in the zone and operable to open and close flow passage means passing through the chamber by way of the wedge elements, the valve member carrying two sealing rings each arranged at a respective surface portion of the valve member and positionable on rotation of the valve member against a respective one of the converging surface portions so as to be tightenable against the respectively associated surface portions, and at least one stressing element so acting on the wedge elements at peripheral regions thereof as to urge the wedge elements against the wall surface portions.

With a valve embodying the present invention, the risk of penetration of solid particles from a medium flowing through the passage means, such particles being present in the medium due to the nature of the medium or else due to impurities that cannot be reliably excluded, between the chamber wall surface portions and contacting surfaces of the wedge elements is effectively eliminated.

Although the construction of the stressing element or elements acting against the wedge elements and the supporting of such stressing element or elements against parts of the casing can be carried out in numerous ways, it has proved advantageous if each wedge element is held by two stressing elements, which are disposed symmetrically of a central plane through the valve member extending in the direction of the valve longitudinal axis and which consequently act on the wedge elements at faces opposite one another in a horizontal plane.

In another advantageous embodiment, the stressing elements extend between the wedge elements diposed on either side of the valve member and are stressed between these elements. The advantage of this arrangement is that the stressing elements, with simultaneous urging of the wedge elements against the chamber wall surface portions, bear against the two edge elements on mutually remote sides of the valve member, so that corresponding bearing surfaces are not required in the casing.

Moreover, the stressing elements may be provided with tightening surfaces and co-operate with corresponding counter-surfaces of the wedge elements, so that the installation of the stressing elements is carried out with prestress. The tightening surfaces of the wedge elements and of the stressing elements may with advantage extend parallel to the converging surfaces of the wedge elements.

The fixing of the stressing elements within the valve casing and in their stressed positions can be carried out in any suitable manner.

One appropriate form of fixing and stressing is by means of tightening screws seated in threaded bores in the valve casing.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic sectional elevation of a rotary valve according to the said embodiment, Figure 2 is a view similar to Fig. 1 but with the valve member and associated seals omitted.

Figure 3 is a cross-section on the line Ill-Ill of Fig. 2, and Figure 4 is a cross-section on the line IV-IV of Fig. 2.

Referring now to the drawings, there is shown a rotary valve 10 comprising a casing 11, which supports in its interior a shut-off ball 1 2 with two metal sealing rings 1 3 and 1 4 disposed on either side of the ball. At their sides remote from the ball, the sealing rings bear against two annular wedge discs 1 5 and 16, which in turn bear against two mutually parallel, planar internal surfaces 1 8 and 1 9 of the casing.The wedge discs are prevented from displacement transversely to the flow direction, as indicated by a double arrow 20, by the fact that they are seated in cylindrical recesses in the valve casing, the recesses starting from the casing inner chamber and concentrically surrounding the wedge discs over a portion of their axial extent.

From the ball 1 2 there extends, transversely to the flow direction, an actuating spindle 21, which is immovably attached rotationally and axially to the ball and which is seated in a housing passage 22, indicated only generally, in such a manner as to be capable of rotation and axial displacement. The rotational capacility of the spindle 21 is indicated by an arrow 23, and the axial displacement capability by a double arrow 24. The spindle 21 is sealed in a known manner in the region of the housing passage 22.

The wedge discs 1 5 and 1 6 possess, on their sides facing the ball 12, inclined surfaces 25 and 26, which together form a wedge-shaped seating, tapering towards the spindle, for the sealing rings 1 3 and 14. It can be seen that when a tightening force oriented towards the actuating spindle is exerted on the ball 12, the sealing rings 1 3 and 14 are clamped between the ball and the inclined surfaces 25 and 26.

The flow path indicated by the arrow 20 extends rectilinearly through the casing 11 and is defined by casing bores 27 and 28 and provided with internal threads, by the central openings in the annular wedge discs and sealing rings, and by a through bore 29 in the ball 1 2. The closure of the flow path is effected by rotation of the ball according to the arrow 23 through 90 with respect to the position illustrated in Fig. 1.

Two stressing elements 30 and 31 are arranged between the wedge discs and disposed symmetrically about a central plane coinciding with the axis of the spindle 21.

These stressing elements, which are arranged so that central portions 32 and 33 thereof extend around the ball 12, have tightening surfaces 34 and 35 extending parallel to the inclined surfaces 25 and 26 of the wedge discs 1 5 and 16, which tightening surfaces co-operate with correspondingly extending tightening surfaces 36 and 37 of the wedge discs.The stressing elements force the wedge discs in their stressed positions apart and the sealing surfaces of the wedge discs that are remote from the ball 1 2 are pressed, in these stressed positions, against the casing surfaces 1 8 and 1 9 in such a manner that even when the ball is in the actuating position, the seal between the afore-mentioned wedge disc surfaces and the casing surfaces 1 8 and 1 9 is maintained, so that any solid particles entrained in a medium flowing along the flow path cannot penetrate between these sealing surfaces.

The stressing elements are held in their stressed positions by means of tightening screws 38 and 39 seated in threaded bores in the casing, the screws extending through appropriate screw holes in clamping flanges 40 and 41 extending perpendicularly to the central portions 32 and 33 of the stressing elements. Between the clamping flanges 40 and 41 of the stressing elements and the adjacent portions of the casing, a clearance of such a size is present that a prestress sufficient to meet the requirements of use can be applied to the wedge discs 1 5 and 1 6 by tightening of the screws 38 and 39 to a greater or lesser degree.

Claims (7)

1. A rotary valve comprising a casing defining a valve chamber with two mutually parallel wall surface portions, two wedge elements each bearing against a respective one of the wall surface portions, mutually facing surface portions of the elements so converging towards each other as to define a generally wedge-shaped zone between the elements, a rotary valve member arranged in the zone and operable to open and close flow passage means passing through the chamber by way of the wedge elements, the valve member carrying two sealing rings each arranged at a respective surface portion of the valve member and positionable on rotation of the valve member against a respective one of the converging surface portions so as to be tightenable against the respectively associated surface portions, and at least one stressing element so acting on the wedge elements at peripheral regions thereof as to urge the wedge elements against the wall surface portions.

2. A valve as claimed in claim 1, comprising two such stressing elements acting on the wedge elements symmetrically about a plane containing the axis of rotation of the valve member.

3. A valve member as claimed in claim 2, wherein the stressing elements each extend between and pressurably bear against the wedge elements at a respective one of two opposite sides of the valve member.

4. A valve as claimed in either claim 2 or claim 3, wherein each of the stressing elements is provided with converging bearing surfaces bearing against complementary surfaces of the wedge elements.

5. A valve as claimed in claim 4, wherein said converging bearing surfaces of the stressing elements and complementary surfaces of the wedge elements extend parallel to said converging surface portions of the wedge elements.

6. A valve as claimed in any one of claims 2 to 5, wherein the stressing elements are held in place by means of tensioning devices threadedly engaged in the casing.

7. A rotary valve substantially as hereinbe fore described with reference to the accompanying drawings.