Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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
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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
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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
