CA2300928A1

CA2300928A1 - Sealing device

Info

Publication number: CA2300928A1
Application number: CA002300928A
Authority: CA
Inventors: Wilfried Starke
Original assignee: Mannesmann AG
Current assignee: Individual
Priority date: 1998-06-19
Filing date: 1999-05-12
Publication date: 1999-12-29
Also published as: AU5148299A; TR200000434T1; JP2002519594A; BR9906545A; IL134573A0; WO1999067554A1; DE19828896C1; EP1030986A1; PL338712A1; KR20010023022A; EP1030986B1; DE59908465D1; ATE259035T1

Abstract

A device for sealing the contact zone between two parts that are movable with respect to each other, of which one forms a shut-off element (1) and the other a sealing seat, contains at least one sealing element formed by a resilient steel strip (2) that extends along the contact zone, is curved to form a hollow section and of which the two longitudinal edges form clamping edges (3) clamped on one of the two parts in contact at a distance from one another equal to at least 10 % of the width of the sealing element. In the closure position of the shut-off element, a sealing zone (4) of the sealing element, which is convex with respect to the sealing seat, is pressed on the sealing seat by a sealing force exercised by the spring. The sealing zone (4) of the resilient steel strip (2) is plastically bent into the shape of a roof with a ridge and two adjacent roof surfaces (5) that enclose an angle from 60~ to 160~. The longitudinal edges of the two roof surfaces (5) away from the roof ridge are plastically bent outward to form another convex bend (6) adjacent to a side surface (7) which is flat at least in a first section and on the free longitudinal edge of which the clamping edge (3) is arranged.

Description

W099/G755s CA 02300928 2000-U2-17 ~~r«~'~/~V~'~/a Sealing device Description This invention has to do with a device for sealing the contact zone between two parts that are movable with respect to each other, one of which is formed as a shut-off element and the other as a sealing seat.
Devices of this type are specifically used to ensure a reliable and gas-tight seal between a movable shut-off element (e.g., a swing-wing or a sliding plate shut-off element) of a shut-off device installed in a large dimension hot gas pipeline and a stationary seat in the housing of this shut-off device. Such hot gas pipelines often have diameters or cross ' sectional diagonals that are several meters wide.
A generic device for sealing the contact zone between a movable shut-off element and a stationary seal is known from Patent DE 195 21 916 A1. This device contains a sealing element that is made out of a resilient steel strip and that can be attached to the movable shut-off element or to the stationary sealing seat, or even to both, however desired. It extends along the contact zone of the sealing seat and the shut-off element and is bent into the shape of a hollow section, so that the resilient steel strip can be curved outwards in convex fashion in the area of the contact zone. Bending the resilient steel strip where it is elastic is bow the permanent curve is usually produced. The two longitudinal edges of the resilient steel strip form clamping edges, each one of which is firmly clamped onto one of the two parts (either the sealing seat or the shutoff element), at a distance to each other of at least 10% of the width of the sealing element. The clamping edges point to the same side, respectively, and lie parallel to each other. In its assembled mode the resilient steel strip has an additional two bends of approximately 94°, respectively, besides the curvature in the area of the arc-shaped sealing zone produced by the permanent bend.
These two bends also were produced by permanently bending the resilient steel strip into shape. Both bends are either arranged in the area between one of the two clamping edges and the arc-shaped sealing zone and are 90° offset at an opposite angle, or they are arranged on various sides between the arc-shaped sealing zone and the respective clamping edge and point to the same side. The distance between the two parallel clamping edges, which are tightened by means of a terminal strip, is ensured by a supporting element that is placed between the clamping edges. Depending on the layout of the bends, this supporting element either is made as an L-shaped section or as a simple flat steel section along one, or along both, clamping edges. In this way this supporting element resides in the interior of the hollow section formed by the curved resilient steel strip. In the case of this known device, this supporting element is supposed to prevent the resilient steel strip from being detached or lied-off' while the shut-off element is in the process of closing. This device in particular has been especially devised for applications W099/6755d CA 02300928 2000-o2-m PcrmE99roia98 where strong tangential frictional forces arise in the direction of the curved sealing zone while the shut-off element is in the process of being closed. The actual sealing power runs as usual in a perpendicular direction to the sealing zone.
A hollow section that is formed from the resilient steel strip and that has a plastically curved sealing zone also is known from Patent DE 38 15 402 A1. These devices were especially used to seal flue or chimney gas pipelines. In the case of the conventional dimensions of a resilient steel strip, its elasticity in the area of the arc-shaped, curved sealing zone is such that ranges of spring or spring excursions of up to approx. 10 mm are possible. This means that thermal expansions of up to 3x3 m in size owing to the effect of the temperature of the hot flue gas on the shut-off device could be compensated for in the case of shut-off elements. But these known sealing devices are no longer able to provide adequate compensation in the case of very large flue gas chimney cross sections of 5x7 m, for example.
A suitable sealing device for flue gas fixtures must not only have adequate elasticity hence, sufficient range of spring or spring excursion to offset the expected thermal expansion, but beyond that also must possess adequate rigidity. The sealing device is exposed to exceptionally strong fluxes or currents of flue gas in its relaxed or non-stressed state, i.e., when the shut-off element is not lying against it. If there is too little rigidity the flue gas currents make the sealing device vibrate naturally. In the long run such vibrations destroy the device.
The task of the present invention is to devise or design a generic device for sealing so that substantially greater spring excursions than heretofore, i.e., ranges of spring on the order of up to 30 mm in particular, are possible to compensate for extremely strong thermal expansion, without thereby unacceptably reducing the rigidity of the sealing.
This task is resolved for a generic device that has the characteristic properties of Patent Claim 1. Useful further developments of the invention are cited in sub- Patent Claims 2 to 12.
Starting out from the generic sealing device, the invention also retains the curved sealing zone. The resilient steel strip, however, is bent essentially as a result of plastic deformation in the form of a roof ridge with two adjacent roof surfaces on both sides in the area of the sealing zone, whereas in the case of the conventional sealing device the sealing zone has been plastically bent. The roof surfaces are essentially designed to be Level, but they also may exhibit a slight curvature towards the inside or outwards. In such a case the bend of the roof ridge, besides the plastic deformation, also exhibits a certain element of elastic deformation. The two roof surfaces made in accordance with the invention enclose an angle of approx. 60 ° to 160 °, and preferably an angle of 90 ° to 130 °. An angle of 105 ° to 115 ° is especially preferred. On the longitudinal edge of the two roof surfaces facing the roof ridge the resilient steel strip of the sealing device made according to the discovery has, in each case, an additional convex bend outwards. These bends are permanently induced by plastic deformation. A side surface tbat is essentially level in at least its initial section is attached to this convex bend, whereupon the clamping W 0 99/67554 CA 0 2 3 0 0 9 2 8 2 0 0 0 - 0 2 - 17 pC't'/pE99101~98 edge is arranged on the free longitudinal edge of this side surface.
Preferably both of the clamping edges are oriented so as to be parallel to each other. This property, however, is not absolutely necesssary. By way of example, the clamping edges also could run towards each other on a slant. In such a case, the distance that lies at the beginning of the clamping edges, hence in the area lying closest to the sealing zone, would constitute the distance of the two clamping edges.
The distance of the two clamping edges from each other must amount to at least 10%, and preferably to at least 20%. Especially preferred is a distance that amounts to at least 30% of the width of the sealing element. The width of the sealing element is the distance of the convex bends facing each other on the longitudinal edges of the two roof surfaces facing the roof ridge. For reasons of efficiency this distance upward is limited to 50% of the width of the sealing element. However, it also is possible to make the distance of the two clamping edges larger, for example just as large as the width of the sealing element.
In such a case the two side surfaces adjacent to the raof surfaces could be designed to be completely level and made parahel to each other. The preferred embodiment form however provides for arranging an additional bend in the area of the side surfaces that, however, is not shaped so as to be convex, but rather concave, outwards. Even this additional bend that runs lengthwise along the resilient steel strip is made permanent by means of bending the plastic.
To maintain the desired distance of the two clamping edges from each other a full or hollow section with a rectangular cross section is used to fill up the intermediate spaoe between the two clamping edges. The rectangular cross section ensures the parallel course of the two clamping edges. In the case of smaller distances the use of a full section is recommended, whereas for larger dimensions a hollow section is more advantageous particularly so as to economize on weight. Preferably, the two clamping edges would be clamped between one such full or hollow section and two terminal strips that were laid out parallel to this section and e.g., were twisted by means of screws. In this connection it is especially advisable to provide one of the two terminal strips with simple through holes for screws used, while the other terminal strip is equipped with machine threaded holes.
This makes it possible to insert the screws used for twisting through the corresponding through holes of the one terminal strip, of the two clamping edges and of the section lying between the clamping edges, and then screw them into the threaded holes of the other terminal strip. In this way the sealing device can be completely assembled as oheaply as possible. The screws used should rise through the threaded holes by a free thread length, so that this free thread length can be attached to the attachment on the respective part of the flue gas fixture hence to the stationary sealing seat or to the movable flap wing by means of an additional nut.
The terminal strips used will suitably possess a rounded longitudinal edge on the side lying on the respective clamping edge. This allows the fixing point or bearing edge cleanly to bend the resilient steel strip. Preferably, the clamping bar or strip is laid out so its rounded longitudinal edge lies in the area of the concave bend of the resilient steel strip. To increase the rigidity of the sealing device made in accordance with the discovery, a level section of the side surfaces of the convex and the concave bend can be W099/67554 CA 02300928 2000-02-17 rv.um:rmu.~ru supported or propped up over a section outwards so that, for example, the respective clamping strip extends into this area and is shaped not as a flat bar of steel but as a suitable angle section. Alternatively, it also is possible to build in or install elastic bracing metal, for example.
The sealing device made in accordance with the discovery produces an exceptionally high-performance sealing for flue gas fixtures for very large flue gas pipes with surprisingly simple tools. The device is not only easily pre-assembled, but can also be finally assembled using very simple tools. Because it makes possible much larger spring excursions even extreme temperature expansions as a result of the effects of the flue gas can be reliably controlled. Beyond that, the sealing device made in accordance with the discovery possesses such a high degree of resilient stiffness that unacceptable vibrations resulting from the strong currents of the flue gas do not arise.
The invention is explained below in greater detail on the basis of the embodiment examples shown in the Illustrations. They show:
Fig. 1 an initial embodiment form of the sealing device made in accordance with the invention in cross section, in both a stressed and unstressed state, Fig. 2 a modification of the sealing device from Fig. 1.
Fig. 3 a sealing device with completely level side walls, and Fig. 4 a sealing device in accordance with Fig. 1, in its assembled state.
Figure 1 shows a sealing device in accordance with the discovery, in cross section.
Continuous lines are used here to show the unstressed state, whereas the dashed lines indicate the deformation arising in its stressed state when it has been affected by high temperatures. The resilient steel strip is a key element of the device in accordance with the discovery and a thick line illustrates this element. In its main or upper section the resilient steel strip has a sealing zone 4 that is shaped in the form of a roof ridge with two level roof surfaces 5. Bending resilient steel strip 2 where it is most elastic produces the permanent bend of sealing zone 4. An additional outwardly convex bend 6 has been arranged on the longitudinal edges of the roof surfaces 5 facing the sealing zone. To them are connected or joined side surfaces 7 that have been shaped so as to be level in an initial section. The two clamping edges of the resilient steel strip are designated by Pan Reference Number 3 and are oriented towards each other with parallel faces. In addition to this, an additional bend 8 has been attached in side surfaces 7 that similarly has been produced by permanently bending the strip. This bend, however, is not convex, but rather shaped so as to be outwardly concave. A rectangular hollow section has been inserted between them to bring the clamping edges into the desired distance to each other. A
terminal strip 10 or 11 lies against the outside surfaces of the two clamping edges 3, so that the clamping edges 3 could be pinched between hollow section 9 and terminal strip 10, 11, for example by means of a screw connection. In this way the resilient steel strip 2 forms a hollow section whose cross section has been designed to be essentially rhomb W099167554 CA 02300928 2000-02-17 iWU~vmumu shaped and whose clamping edges form more or less a foot or base at the comer of the rhombus of the cross section. This makes it possible to assemble the. sealing device easily. In the embodiment example shown, the two terminal strips 10, 11 each have a rounded longitudinal edge whose radius of rounded end is conformed to the radius of rounded end of the concave bend 8. The two terminal strips 10,11 extend with their rounded longitudinal edges into the area of bend 8. Parts Reference Number 1 designates the part of the shut-off element that lies against the curved sealing zone 4 when sealing force is being exerted. The dotted lines illustrate the situation of the deformation of the resilient steel strip 2 when it has been affected by strong thermal expansion.
Sealing zone 4 is shifted downwards under the pressure of shut-off element 1 so as to enlarge the angle in the area of the roof ridge, on the one hand, and scale down the angle in the area of the two bends 6, on the other. One can clearly see that the sealing device in accordance with the discovery, despite its compact construction, permits a very large excursion of spring.
At the same time, the rigidity of the spring is still too great for there to arise unacceptable vibrations of the resilient steel strip 2 despite powerful flue gas velocities which could result in its being destroyed prematurely.
The sealing device illustrated in Fig. 2 is largely identical to the embodiment example of Fig. 1. It only differs from the former in the fact that its two terminal strips 10,11 with their rounded edges do not extend into the area of the concave bends but come to an end shortly before them. In this way the rigidity of the spring can be consciously reduced. Conversely, when using the identical same resilient steel strip 2 the rigidity of the spring could be appreciably increased as needed if the two terminal strips 10,11 were to be extended upwards into the area of the side surfaces 7 in the shape of an angle section conformed to the contour of the resilient steel strip 2, by way of example.
Reducing the distance of the two clamping edges 3 from each other also decreases spring rigidity, whereas making the distance bigger increases spring rigidity. Fig. 3 illustrates an extreme or limit case in this regard. In this illustration the two clamping edges 3 have a distance from each other that corresponds to the width of the sealing element.
The two side surfaces 7 are made so as to be completely level, hence they do not have any concave bend.
Fig. 4 illustrates the sealing device in accordance with the discovery, whose embodiment corresponds to Fig. 1, in its assembled state. The clamping edges of the resilient steel strip 2 are clamped between the two terminal strips 10,11 and the hollow section 9 arranged between them by means of a screw 12. Whereas terminal strip 10 and hollow section 9 have only been provided with through holes for screw 12, terminal strip 11 has a tap, or machine threaded hole conformed to receive the screw thread of screw 12. In this way the sealing device can be prepared in its pre-assembled state without having to use a special nut. As a rule this seal is manufactured in standard lengths of, e.g., 2 m and only during assembly it is shaped to the desired overall length in the flue gas fitting. The system part to which the sealing device is supposed to be attached has been given Parts Reference Number 13 in Fig. 4. Like hollow section 9 and terminal strip 10, it also has a through hole -that is suitable for screw 12. Screw 12 has been made to be significantly longer than would be required were it only to be screwed using the threaded hole in wU~'J167~s~1 CA 02300928 2000-02-17 a terminal strip 11. As a result, the free ends of screws 12 can be inserted , into these through holes on part 13 and then securely anchored together with it by means of nut 14.

WV99167JS~ CA 02300928 2000-02-17 Parts Reference List 1 Shut-off element 2 Resilient steel strip 3 Clamping edges 4 Sealing zone Roof surfaces 6 Bend (convex) 7 Side surface 8 Bend (concave) 9 Hollow section Terminal strip 11 Terminal strip 12 Screw 13 System part 14 Nut

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A device for sealing the contact zone between two parts that are movable with respect to each other, one of which forms a shut-off element (1) and the other a sealing seat, containing at least one sealing element formed by a resilient steel strip (2) that extends along the contact zone, which is curved to form a hollow section, and whose two longitudinal edges form clamping edges (3) that clamp on one of the two parts at a distance to one another that is equal to at least 10% of the width of the sealing element, whereby the sealing element in the closure position of the shut-off element is pressed onto the sealing seat by a sealing force exerted by the spring so as to have a sealing zone (4) that is convex with respect to the sealing seat, characterized by the fact that - the sealing zone (4) of the resilient steel strip (2) is permanently bent into the shape of a roof with a ridge and two adjacent roof surfaces (5);
- the two roof surfaces (5) are oriented to each other at an angle from 60° to 160°; and - the longitudinal edges of the two roof surfaces (5) opposite the roof edge are permanently bent outward to form another convex bend (6) adjacent side surface (7) that is flat at least in its first section, and on whose free longitudinal edge the clamping edge (3) is arranged.

2. A device in accordance with Patent Claim 1, characterized by the fact that the surfaces of the clamping edges (3) are laid out so as to be parallel to each other.

3. A device in accordance with Patent Claims 1 to 2, characterized by the fact that an additional bend (8) designed to be concave outwards is produced by plastic deformation longitudinally in both side surfaces (7) of the resilient steel strip (2).

4. A device in accordance with Patent Claims 1 through 3, characterized by the fact that the two roof surfaces (5) are oriented towards each other at an angle of 90° to 130°, and at an angle of 105° to 115°, in particular.

5. A device in accordance with one of Patent Claims 1 to 4, characterized by the fact that the distance of the two clamping edges (3) from one another amounts to at least 20%, and at least 30%, in particular, of the width of the sealing element.

6. A device in accordance with one of Patent Claims 1 to 5, characterized by the fact that the distance of the two clamping edges (3) amounts to not more than 50%
of the width of the sealing element.

7. A device in accordance with one of Patent Claims 1 to 6, characterized by the fact that the space between the two clamping edges (3) has been filled by a full or hollow section (9) with a rectangular cross section.

8. A device in accordance with Patent Claim 7, characterized by the fact that the two clamping edges (3) are clamped between the full or hollow section (9) and the two terminal strips (10,11).

9. A device in accordance with Patent Claim 8, characterized by the fact that the gripping is done by means of screw connections, whereupon one of the terminal strips (10) has through holes and the other terminal strip (11) machined thread holes for the screws (12), and the screws (12) for attaching the sealing element to one of the parts (13) by means of a nut (14) rise or project through the screw taps by a free threaded length.

10. A device in accordance with Patent Claims 8 to 9, characterized by the fact that each of the terminal strips (10,11) has a rounded longitudinal edge on the side lying on the clamping edge (3).

11. A device in accordance with Patent Claim 10, characterized by the fact that in each instance the rounded longitudinal edge lies in the area of the concave bend (8) of the resilient steel strip (2).

12. A device in accordance with one of Patent Claims 3 to 11, characterized by the fact that, to increase the rigidity of the spring, the level section of side surfaces (7) of the convex (6) and of the concave bends (8) is supported or under-propped over a partial area from the outside.