Seal for a joint or juncture – Seal between relatively movable parts – Piston ring or piston ring expander or seat therefor
Reexamination Certificate
1999-02-01
2001-02-27
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Piston ring or piston ring expander or seat therefor
C277S446000, C277S489000, C277S493000, C277S494000
Reexamination Certificate
active
06193236
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a packing seal which is intended in particular for reciprocating piston engines and which is preferably placed into a circumferential groove of a piston of such a reciprocating piston engine.
2. Description of Related Art
With reference to
FIG. 2
of the attached drawings, a seal in the form of a packing seal is shown which is known from WO 95/14184. The packing seal marked
10
overall comprises at least two axially adjacent segment rings
1
, which each have several sealing segments
3
and also many locking segments
4
. The sealing segments
3
and the locking segments
4
taper in this case in a wedge-shape in opposite directions radially inward and outward, respectively, in both segment rings
1
. These segments are provided inside each segment ring
1
in alternating order. The sealing elements
3
of the at least two segment rings overlap alternately and, by means of at least one spring element
2
, such as a bearing spring washer, they are prestressed radially outward against a cylindrical wall—not shown—of a reciprocating piston engine, for example. Provided between the at least two segment rings
1
is a torsion protection formed by a bore
8
and an adjusting pin
9
. The bores
8
penetrate two overlapping sealing segments
3
of the two axially adjacent segment rings
1
. The torsion protection formed in connection with the two bores
8
and the adjusting pin
9
ensures that the provided reciprocal overlapping of the sealing segments
3
is maintained. So with this known packing seal, there must be a spring element
2
, such as a bearing spring washer, which is responsible for the flawless functioning of the seal designed as packing seal. This spring element must exert a predetermined elastic force, directed in predetermined manner, throughout the useful life of the seal, although the spring element is exposed to high and also changing temperatures. Furthermore, the elastic force must be great enough that even under the action of high ignition and/or combustion pressures, the locking parts of the segment ring directly under pressure will not be pressed out of the overall arrangement. Thus, it has been shown that such a spring element must be designed relatively thick, in such a way that considerable groove depths are needed to receive the entire packing seal. Such considerable groove depths may lead to vibration problems that become noticeable as fluttering. This occurs in particular with high-speed, powerful engines, e.g. racing engines, and is attributable to resonance effects. In particular, with the aforementioned known seal it has been shown that the spring element necessary for operation entails not only an expense with respect to production, but in particular extensive changes are also necessary with a view to receiving the packing seal, and such a spring element impairs the functioning of the seal to the effect that when the readjusting rate of the spring element is reduced, changing energy generation and impact make possible—if only in the short-term—an undesired, increased passage of gas, which is also designated as “blow-by”. Of course, a loss of power is inevitably connected with this.
On the other hand, the invention aims to provide a packing seal of the generic kind—overcoming the aforementioned difficulties—which ensures, with a simplified assembly and reliability of use, an arrangement of the sealing segments of the packing seal.
BRIEF SUMMARY OF THE INVENTION
According to the invention, for this object a packing seal is provided that has at least two axially adjacent segment rings that each have at least two sealing segments and, to avoid an abutting of the sealing segments, have locking segments arranged between them in alternating order, whereby the sealing segments and the locking segments of at least a first segment ring taper wedge-shaped in opposite directions radially inward and outward, respectively, and the locking segments are set back radially relative to the sealing area of the sealing segments, and the packing seal furthermore has a torsion protection acting between the at least two segment rings, whereby the packing seal distinguishes itself in that the alternating locking and sealing segments of the at least one additional segment ring both taper radially inward, the locking segments extend over a substantially larger arc area than the sealing segments, and that the sealing segments of this additional segment ring overlay only the lock elements of the axially adjacent first segment ring of the packing seal.
In the packing seal according to the invention, a spring element acting as bearing spring can thus be dispensed with, in such a way that the possible impairments—previously existing in this connection—of the known packing seal can be effectively eliminated. Production of the packing seal and assembly thereof is also thereby simplified, because no additional part is needed, such as the bearing spring necessary for operation. In the packing seal according to the invention, this closing function of the seal limits, as well as a reliable arrangement of the sealing segments on the related sealing counter-surfaces, is taken over by the novel design of the at least one additional segment ring. With this additional segment ring, unlike the typical design described in the beginning, the design is made such that the alternately arranged sealing segments and locking segments do not taper in opposite directions, but rather both taper radially inward.
Furthermore, since the respective locking segment of this additional segment ring extends over a larger arc area than the related sealing segments, working pressure of this additional segment ring always reliably results in effective force conditions such that the sealing segments are reliably pressed toward the seal limit to be closed, in such a way that in any operating status and working condition, the sealing segments of the additional segment ring—essential according to the invention—move reliably, necessarily and automatically in the direction of the counter-surface, and in this direction they come under a force of pressure to produce the bearing pressure against the counter-surface.
Furthermore, since the respective sealing segments of the additional segment ring under pressure cover the respective locking segments of the axially adjacent first segment ring, the pressure in the groove base of the groove intended for insertion of the packing seal is sufficient to affect the locking segments of the first segment ring with the effective direction outward in such a way that the segment ring bond of this first segment ring is maintained. This ensures a reliable cooperation of the at least two segment rings in such a way that only dependent upon the respective operating pressure or working pressure, the sealing segments of the at least two axially adjacent segment rings are reliably and immediately brought to rest against the counter-surface under the action of a bearing pressure in such a way that the seal limits are reliably closed and a passage of gas is efficiently prevented.
As can be seen from the preceding explanations, the present invention, even while reducing the construction expense and reducing the number of parts of the packing seal, thus creates an effective remedy for the possible problems of an increased passage of gas, that is, a so-called blow-by. The packing seal according to the invention thus prevents a breaking open of the seal limits at the segment rings, while making use of the working pressures present when the machine is in operating status, in such a way that the procedure of arrangement of the sealing segments is carried out automatically by the working pressure in the manner desired at any given time, reliably and without auxiliary means. This is surprisingly possible in that the taper direction of the locking segments and the sealing segments of the additional segment ring essential according to the invention is selected parallel on the one hand, and on the other hand, that it is dir
Beres John L.
Knight Anthony
Kubovcik & Kubovcik
LandOfFree
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