GB2147392A - Shut off valve for ducts - Google Patents

Abstract

A shut off valve for smoke or gas ducts comprises a closing member (2) pivotably mounted by an axle (4) so as to be turnable from an open position, wherein the closing member (2) is in a recess formed in a duct wall, to a closed position across the duct. The axle (4) is hollow and therein is arranged an axle (9) provided with eccentric elements (10), so that when axle 9 is turned within axle (4) the closing member (2) in closed position is moved in the axial direction of the duct and pressed against surface S, e.g. flanges (19) of the duct. The axle (4) is provided with sealing flanges (14) inside the duct, and outside the duct ring seals (15) are arranged pressed in place by members (16, 17). <IMAGE>

Description

SPECIFICATION Shut off valve for smoke gas ducts etc.

The invention relates to a shut off valve particularly for smoke gas ducts.

Pivotable dampers with one or several vanes are at present generally used as closing members of gas ducts. Their disadvantage is that the tightness in the closed position is insufficient. Leakages appear especially at the ends of the dampers; a relatively broad gap has to be left between the ends of the dampers and the duct wall in order to prevent the dampers from sticking in the open position because of the soot and cinder accumulating in the gap. In practice, however, the dampers often stick, almost entirely, whereby it is very difficult to turn them to the closed position.

Besides, sooting and falling cinder cause leakages at the closing surfaces between the damper vanes.

From the Finnish Patent Publication 29416 a closing valve of another type is known, the closing member of which is a calotte-shaped valve disc, which by means of linkage is turnable from a position by the duct wall to a position in which it diagonally closes the duct, the convex side of the valve disc being turned against the gas flow. This closing valve functions well as such, but as a whole, it has a rather complicated stucture and requires accurately dimensioned seal fits, which makes it too expensive.

It is an object of the invention, by using the general closing method described in the Patent Publication 29416, to provide a new shut off valve, which has a simple structure, is easy to use and moreover, secures a good tightness in the closed position.

Thus, the invention concerns a shut off valve for smoke gas ducts etc. comprising a closing member pivotable on an axle, whereby one of the walls of the duct parallel with the axle is provided with a recess to receive the closing member, when the valve is open.

The invention is characterized in that the axle of the closing member is hollow, that a turntable axle is fitted therein, which turnable axle is journalled in the duct walls and is provided with eccentric elements carrying the axle of the closing member and which turntable axle, together with its eccentric elements, is turnable with respect to the closing member, whereby the closing member is at first pivotable from the open position along a circular arc to the closed position and is thereafter, by turning the turnable axle provided with eccentric elements, movable in the longitudinal direction of the duct, and that the duct walls are equipped with elements against which the edge portions of the closing member are pressed as the closing member is moved in the longitudinal direction of the duct.

Below, the invention is described in greater detail with reference to the attached schematic drawings.

Figure 1 illustrates-a longitudinal section of a gas duct with a shut off valve.

Figure 2 illustrates a section along the line Il-Il of Fig. 1.

A smoke gas duct, the cross-section of which preferably is rectangular, is marked by reference numeral 1. A closing member or valve therefor is a curved plate 2, the ends of which are fastened by means of e.g. sectorshaped plates to a hollow axle 4. Within the hollow axle 4 is arranged a separate turnable axle 9, which is carrying the axle 4 from the inside by means of eccentric plates 10 and the bearing 11 of which is stationarily supported by the duct walls 1c and id. One of the walls of the duct 1 being parallel with the axle 4, namely wall 1 a, is provided with a recess 5 to receive the closing member 2, when the duct 1 is held open. It is possible to provide the lower part of the recess 5 with a stop pin 6, alternatively the axle 4 can be locked in one way or another. The open position of the valve is indicated by broken lines in Fig. 1.

The closed position of the valve is indicated by continuous lines in Fig. 1. The closing member 2 then extends over the duct 1 and its edge portions perpendicular to Fig. 1 can on one hand abut against the surface 5a of the recess 5, adjacent to the duct wall 1 a, and on the other hand, against a support surface 8 of a notch 7 formed in the opposite wall ib.

The closing member is turned by means of a lever 1 3 out of the recess 5 over the duct 1, supported by the stationary eccentrics 10 attached to the turnable axle 9, whereafter the axle 9 is turned by means of a lever 1 2 to the position of Fig. 2, whereby the eccentrics 10 turn within the hollow axle 4 and press the edges of the end plates 3 of the closing member against flanges 1 9 projecting from the duct walls ic and id. It is also possible to provide the walls 1 a and 1 b with corresponding flanges to replace the supporting surfaces 5a and 8.

To seal the openings made in the walls 1 c and 1 d for the axle 4, the axle 4 is provided with flanges 14 also guiding the axial movement of the closing member and outside these flanges 14 are located sealing rings 15, which at the same time abut against the edge of the wall opening. The sealing rings 1 5 can preferably be so-called braid sealings and to press them in place rings 1 6 are used, which rings are from the outside fastened to supporting members 1 8 and are provided with an inside conical collar 1 7.

To facilitate the turning of the closing member 2, a counterweight 20 can be fastened to the axle 4.

The fastening arms 21 of this counter weight are preferably so dimensioned that when the valve is open the counterweight abuts to the wall 1 b, which also can be provided with a receiving recess for the counterweight.

The eccentrics 10 of the axle 9 are dimen sioned e.g. so that the culmination of the movement has not yet been reached when the closing member 2 meets the flanges 1 9. The lever 1 2 can e.g. be connected with the piston rod of a hydraulic or pneumatic cylinder, whereby the position each time can easily be locked by means of the cylinder. It is naturally also possible to turn the lever 1 2 by hand and to arrange a suitable mechanical locking by means of the lever.

In addition to the shut off valve of the invention reliably closing the duct 1 and being easy to operate, it is also more advantageous than prior shut off valves in that it, in the open position of the closing member 2, does not at all throttle the gas flow, because the whole closing member is in the recess 5 and the space required for the axle 4 and the supporting plates 3 is smaller than the enlargement of the cross-sectional area of the flow provided by the recess 5, when the closing member 2 is located therein.

According to the drawing, the axle 4 is preferably placed in the centre of the circular arc of the closing member 2, but this is not necessary as such. Neither is it necessary that the form of the closing member is a part of the envelope surface of a cylinder, but as to the forming of flanges 19, the embodiment of the drawing is the simpliest one.

The radius of curvature R of the closing member 2 should preferably be so big, approximately 0.75 x diameter C of duct 1 that the closing member entirely leaves the "proper" duct, when the valve is open, as illustrated in Fig. 1. On the other hand, there is no reason to enlarge the radius of curvature R very much, because the bulge or the recess 5 to be formed in the duct wall grows bigger when R grows bigger.

Claims (5)

1. Shut off valve for smoke gas ducts etc., comprising a closing member pivotable on a hollow axle, one of the walls of the duct parallel with the axle being provided with a recess to receive the closing member when the valve is open, there being a turnable axle fitted in the axle which turnable axle is journalled in the duct walls and is provided with eccentric elements carrying the axle of the closing member and which turnable axle, with its eccentric elements, is turnabie with respect to the closing member, whereby the closing member is at first pivotable from the open position along a circular arc to a closed position and is thereafter, by turning the turnable axle provided with eccentric elements, movable in the longitudinal direction of the duct, the duct walls being equipped with elements against which the edge portions of the closing member are pressed as the closing member is moved in the longitudinal direction of the duct.

2. Shut off valve according to Claim 1, in which the axle of the closing member is provided with cover flanges adapted to slide along the inner surface of the duct walls and with outer seals.

3. Closing valve according to Claim 2, in which the outer seals comprise a sealing ring abutting against the cover flange and against the edge of the opening in the duct wall and a ring disc to be fastened to the duct wall from outside, which ring disc is provided with a conical collar to press the sealing ring in place.

4. Closing valve according to Claim 1, in which to facilitate the pivoting of the closing member a counterweight is attached to the hollow axle.

5. Shut off valve for smoke gas ducts etc., substantially as hereinbefore described with reference to the accompanying drawings.