Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2002-02-04
2004-02-17
Knight, Anthony (Department: 3676)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S504000, C277S549000, C277S572000, C277S581000, C162S360300, C100S15500G
Reexamination Certificate
active
06692008
ABSTRACT:
The present invention relates to a sealing arrangement for closing off an end of a chamber formed between a plurality of rollers of a pressing apparatus.
For some years attempts have been made to develop a new method for removing water from paper. The new method envisaged was to use compressed air to displace water from a sheet of paper. It was envisaged that a cluster of e.g. four rollers could be used to create an enclosed area that would be sealed by the four nips formed by the rollers as shown, for example, in FIG.
1
. If the ends of the four rollers could be sealed off, the space between the rollers could be pressurized and this could create unique wrap processing conditions.
FIG. 1
is a schematic side view of an example of such a pressing apparatus
10
which is particularly useful in paper making. The pressing apparatus
10
comprises a plurality of rollers to define at least one chamber. In the present exemplary embodiment four rollers
12
,
14
,
16
,
18
are provided to define one chamber
20
. For convenience, sometimes rollers
14
,
18
will be referred to as main rollers and rollers
12
,
16
will be referred to as cap rollers.
The rollers
12
,
14
,
16
,
18
are closed hollow cylinders. In the present exemplary embodiment roller
14
is a vented main roller.
As shown in
FIG. 1
, a membrane
22
travels in the direction of arrow
24
and is routed over a portion of the circumferential surface of cap roller
12
, passes into inlet roller nip
26
, passes over a portion of the circumferential surface of vented main roller
14
within chamber
20
, passes out of outlet roller nip
28
, passes over a portion of the circumferential surface of cap roller
16
, and travels in the direction of arrow
30
. Between the membrane
22
and the vented main roller
14
, a felt
32
and the sheet
34
pass over the mentioned portion of the circumferential surface of the vented main roller
14
, with the sheet
34
being disposed between the membrane
22
and the felt
32
. Behind the outlet roller nip
28
, in the region of cap roller
16
, the felt
32
is separated from the sheet
34
which then travels together with the membrane
22
in the direction of arrow
30
.
The advantages of such a configuration and its uses are many, but briefly, the rolling nips allow for a web to be passed into a pressurized area. The nips in this arrangement all turn at similar surface speeds, so that the seal created by these nips do not wear appreciatively and the web itself is not disrupted as it passes into the pressure zone. Once in the pressure zone, the web is acted upon by whatever medium that is inside the pressure zone, The pressure and speed of the system can control the needs of the process.
In general, more than four rollers could be provided and more than one chamber could be defined by these rollers.
To be able to pressurize the respective roller cluster, it is vital that there is a good seal on the ends of the rollers. The seal needs to be long-lasting and it should have low leak rates. Furthermore, it must operate under the changing pressure within the chamber formed by the respective roller cluster.
Many seal designs exist, however none is known that operates at higher speeds and pressures and has the required life.
It is an object of the present invention to provide a face sealing arrangement that closes off the end of a roller cluster press or a so-called Beck Cluster Press, allowing the press to be pressurized.
Another object of the invention is to develop a seal arrangement that has low wear and gives long life due to its low sealing pressure,
Another object of the invention is to develop a self-loading and self-regulating seal arrangement that maintains low sealing pressure regardless of the pressure to be sealed.
Another object of the invention is to provide a seal arrangement that generates low heat, and that can be made in any arbitrary shape, which can be adapted to fit the unique sealing geometry of the displacement press arrangement.
Another object of the invention is to provide elements and materials that allow the seal to adapt to non-uniform sealing surfaces so that the seal can seal immediately.
Another object of the invention is to create a seal geometry that allows the seal to wear in quickly early in life yet have low wear rates after the initial seal break in.
Another object of the invention is to provide a seal arrangement which includes elements that allow for easy determination of leaks or misalignment of the sealing elements or roller ends.
Another object of the invention is to provide a sealing arrangement which allows an easily replaced seal element.
According to the invention, these and other objects are achieved by the sealing arrangement as defined in the claims.
The present invention provides a sealing arrangement for closing off an end of a chamber formed between a plurality of rollers of a pressing apparatus, wherein said sealing arrangement comprises a seal member made of hard seal material such as carbon fiber material.
Such a sealing arrangement allows minimized surface contact of the seal. With the smaller contact surfaces friction and heat are reduced. This is to be seen as a great advantage of the invention, since large contact surfaces were not desired since they create friction, and heat and add little to the seal effectiveness. Heat and friction on the other hand were detrimental and limited seal life. With the seal material being very strong, the contact area can be kept small. It was found that composite materials using carbon fiber was excellent for seal construction. By using standard carbon fiber construction techniques, a very strong surface could be created that had excellent lubrication properties. As the carbon fiber wears, the wearing materials created would tend to lubricate the seal area, extending the life of the seal. In addition, the carbon fiber seal material is inert, and can be made to withstand high temperatures, that might be experienced later a in the development of the displacement process.
The hard seal member can form a hollow body, with the wall of said hollow body being normal to the end faces of the rollers. The height of said hard seal member is preferably greater than the width of its wall.
Thus, another feature of the sealing arrangement according to the invention is the potential for long life. Since the hard seal member can be vertically orientated, i.e. be normal to the end faces of the rollers, the life of the seal depends on the height of the seal material used. The seal will run until the “wear distance” has become very small. In general terms, to increase the life of the seal by 2, e.g., this height can be increased by 2. There are practical limits to this approach, but with a corresponding arrangement, it is possible to make a very long lasting seal, since there is little to prevent one from making a very tall seal.
In accordance with a preferred embodiment the hard seal member has a seal contact surface that is about 1.02 mm to about 2.54 mm wide.
Another observation was that seal life would be greatly increased if the pressure on the sealing surface could be kept as low as possible. To create a mechanical seal, the seal must only contact the sealing surface. Any additional force beyond that required to maintain contact serves no useful purpose, and causes seal wear.
Therefore, in accordance with a preferred embodiment, the sealing arrangement is a self loaded sealing arrangement. Thus, the necessary sealing forces are generated by the seal construction itself.
The self loaded sealing arrangement may comprise a seal piston which is movable within a cylinder wall, with said seal piston comprising said hard seal member. The seal piston can have a piston ring which seals the piston to said cylinder wall yet allows the piston to remove relatively to this cylinder wall.
In accordance with a preferred embodiment said seal piston comprises a seal holder having a seal plate and an outer annular lip, and wherein said hard seal member is disposed in the region of said lip and reaches beyond said lip to
Boswell Christopher
Knight Anthony
Taylor & Aust P.C.
Voith Paper Patent GmbH
LandOfFree
Sealing arrangement does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sealing arrangement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sealing arrangement will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3338838