Centred butterfly valve

Abstract

Valve comprising a body (2), a centred butterfly (1), mounted with the ability to rotate inside the body (2) from an open position revealing the passage to a closed position covering said passage, and a seal (3) arranged inside a housing which is delimited by the seat and by a face, opposite the seat in the closed position, of the butterfly, the seat and the face converging towards the inside in the axial direction. The seal (3) moves freely in the housing.

Claims

1. A valve comprising: a body defining, by means of an annular internal seat, an internal area forming a passage with an axial direction, a centred butterfly mounted with the ability to rotate inside the body from an open position revealing the passage to a closed position covering said passage, a seal arranged inside a housing which is delimited by the seat and by a face, opposite the seat in the closed position, of the butterfly, the seat and the face converging towards each other in a direction of a rotational axis of the centred butterfly, characterized in that, in the closed position, the seal is free to move in its entirety in all directions inside the housing.

2. The valve according to claim 1, characterized by a means of preventing the seal leaving the housing simply by moving without being deformed.

3. The valve according to claim 2, characterized in that said means is an anti-ejection ring.

4. The valve according to claim 2, characterized in that said means is a circumferential groove inside the body.

5. The valve according to claim 1, characterized in that a housing dimension in the axial direction is larger than a seal dimension in the axial direction by between 1 and 50% of the seal dimension in the axial direction.

6. The valve according to claim 5, characterized in that the housing dimension in the axial direction is at a position on the housing that is furthest from the inside than any other position on the housing.

7. The valve according to claim 1, characterized in that a housing dimension in a radial direction perpendicular to the axial direction is larger than a seal dimension in the radial direction by between 1 and 50% of the seal dimension in the radial direction.

8. The valve according to claim 7, characterized in that the housing dimension in the radial direction is at a position on the housing that is furthest from the inside than any other position on the housing.

9. The valve according to claim 1, characterized in that the seal is an O-ring or lip seal.

10. The valve according to claim 9, wherein the seal is energized by an elastic core.

11. The valve according to claim 1, characterized in that said valve is furnished with two seals on either side of the butterfly in the closed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The attached drawings, which are reproduced purely by way of example, show the following:

(2) FIG. 1 is a perspective view with a partial cutaway of a butterfly valve according to the invention;

(3) FIG. 2 is a partial sectional view of the above when the valve is closed;

(4) FIG. 3 shows the state of a lip seal when energised in the free state;

(5) FIG. 4 shows this seal when it is pressurised and

(6) FIGS. 5 and 6 are larger-scale views of the left-hand side only of FIG. 2 as circled.

DETAILED DESCRIPTION OF THE INVENTION

(7) The butterfly valve according to the invention comprises a centred butterfly 1 with the ability to rotate subject to the action of a drive shaft 5, where the face opposite the seat (sealing zone) is an inclined sealing surface. The valve also comprises a body 2 defining an annular internal seat. The butterfly 1 is centred on the body 2. Finally, the valve comprises a seal 3 on one side of the body 2, maintained securely in the housing defined between the seat of the body 2 and the face of the butterfly 1 opposite the seat, by an anti-ejection ring 4 or in a groove in the body 2, but free to move in its entirety inside the housing. The seat and the face converge progressively towards the inside in the axial direction. A seal 8 of the drive shaft 5/body 2 is provided to prevent leaks when the valve is in the open position.

(8) The seal 3 has an internal diameter that is smaller than the maximum external diameter of the butterfly 1 and an external diameter that is larger than the minimum internal diameter of the seat of the body 2.

(9) As shown in FIG. 5, where the seal 3 is shown by an unbroken line in the position it is in when the fluid pressure is applied to the seal and as a dotted line when no fluid pressure is applied to the seal, an axial dimension a of the housing of the seal 3 permits an axial freedom b of movement of the seal 3 equivalent to 1 to 50% of the axial dimension c of the seal 3 in a housing position further to the left of the figure than a different position closer to the inside.

(10) As shown in FIG. 6, where the seal 3 is shown in a possible position, in which the fluid pressure is not applied to the seal, a radial dimension d of the housing of the seal 3 permits a radial freedom e of movement of the seal 3 equivalent to 1 to 50% of the radial dimension f of the seal 3.

(11) In the version with two seals, the valve is symmetrical in relation to the median plane P (FIG. 2). Sealing in the upstream/downstream direction (seat of the body/seal/face opposite the seat of the butterfly) is axisymmetrical with respect to the axis of the fluid flow or the pipe. It comprises a seal 7 between the body 2 and the piping T to prevent leaks to the outside and a seal 8 between the shaft 5 and the body 2 to prevent leaks to the outside when the valve is in the open position. The distance between the median plane of the seal 3 when it is in a tangential position to the seats and the face opposite the ring 4 is less than or equal to the diameter of the cross-section of the seal 3.

(12) FIG. 3 shows the position of an energised lip seal when the butterfly is in the open position. The elastic core 6 of the seal does not apply the seal to the body 2 and to the butterfly 1. In FIG. 4, the two lips of the seal are pressed respectively on the butterfly 1 and the body 2 by fluid pressure forces, which act against the return force of the elastic core 6.