Seal for a joint or juncture – Process of dynamic sealing – Peripheral radially sealing flexible projection
Reexamination Certificate
1997-12-11
2001-07-31
Mah, Chuck Y. (Department: 3626)
Seal for a joint or juncture
Process of dynamic sealing
Peripheral radially sealing flexible projection
C277S311000, C277S308000, C277S589000
Reexamination Certificate
active
06267380
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a choke arrangement including a choke ring with a parting joint and a support ring. The invention relates further to a method for the operation of the choke arrangement.
2. Description of the Prior Art
Sealing rings are usually arranged pairwise one behind the other in series and form, in this manner, a so-called packing. The pressure difference acting on the individual sealing rings causes their sealing surfaces to be pressed onto the sliding surfaces of the body to be sealed, for instance a piston rod. In addition, a choke arrangement comprising at least one choke ring is arranged at one side of the packing. A packing of this kind with a choke ring and sealing rings is known, for example, from the patent CH 439 897. The choke ring of this known arrangement has the disadvantage that pulsating pressure components are only insufficiently damped. This leads to rapid wear of the sealing rings arranged behind it.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome these known disadvantages of choke rings.
The choke arrangement in accordance with the invention comprises a choke ring which, in a preferred embodiment, consists of a single piece with a parting joint forming a gap. In addition, the choke ring has elastic behavior. The choke arrangement further comprises a support ring which is placed to lie directly adjacent to the choke ring in the axial direction, with the support ring serving, among other things, to cover over the parting joint of the choke ring so that the choke arrangement is impervious in the region of the parting joint. The choke ring requires no further elements such as, e.g. a hose spring surrounding the ring. The choke ring is placed directly against the sliding surface of the body to be sealed, e.g. a piston rod. An advantage of the choke arrangement with an elastically resilient choke ring having a parting joint is to be seen in the fact that the choke ring reacts to dynamic changes in pressure and in so doing changes its sealing properties. The choke arrangement in accordance with the invention is suitable, in particular, for damping pressure peaks such as can arise at the piston rod of a dry running piston compressor. A pressure peak causes an increased pressure difference at the choke arrangement through which the elastic choke ring is pressed against the sliding surface of the piston rod and produces a higher sealing action so that the pressure peak cannot propagate to a sealing ring placed after the choke arrangement. The choke ring in accordance with the invention is executed as a highly leaky ring which hardly seals off constant pressure components at all. As a result of its elastic properties the choke arrangement in accordance with the invention, however, has a high adaptability in form with respect to the piston rod for dynamic pressure components so that it lies in contact with the piston rod as a result of a dynamic pressure rise and seals to an increasing extent. The high adaptability in shape is enabled among other things by the choke ring having a parting joint forming a gap in the peripheral direction. The parting joint is made in such a manner that it does not close even when the choke ring is dynamically pressed against the piston rod in order to thus achieve an adaptability in shape which is as advantageous as possible. The choke arrangement in accordance with the invention has the advantage that it seals off only the dynamically variable pressure components, with the ability of the choke arrangement to respond being variable within a wide range through the geometrical execution of the choke ring, its elastic properties, and further parameters such as the choice of material. The choke arrangement thus behaves analogously to a frequency selective filter known from electrical engineering in which high frequency pressure changes are sealed off whereas static or slowly varying pressure components are not sealed off.
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Mah Chuck Y.
Maschinenfabrik Sulzer-Burckhardt AG
Patel Vishal
Townsend and Townsend / and Crew LLP
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