Valves and valve actuation – Hermetic flexible wall seal for actuator – Bellows
Reexamination Certificate
2000-04-28
2001-08-07
Chambers, A. Michael (Department: 3753)
Valves and valve actuation
Hermetic flexible wall seal for actuator
Bellows
C137S015190, C137S015240, C137S614040
Reexamination Certificate
active
06270055
ABSTRACT:
DESCRIPTION
The invention relates to a hydraulic shut-off valve with a valve insert which has a valve spring, a holding element and a valve seat, and the valve spring, the holding element and the valve seat are designed as a two-piece or one-piece component, the valve spring being designed as a body which has a cavity.
Hydraulic shut-off valves of this kind are known in hose couplings which are of the type which shut off on both sides and act as quick-closing couplings. In these known couplings, the connection is established by pushing the coupling sleeve onto the coupling nipple, during which process the coupling sleeve latches with the coupling nipple by way, for example, of a ball catch. When the sleeve is pushed onto the nipple, the two valve inserts are raised from their sealing surfaces and establish the connection between the two hose ends. The valve inserts of these known hose couplings consist of a plurality of individual parts which are generally plugged into one another. Here, the holding element acts as a fastening element for the complete valve insert in the coupling nipple or in the coupling sleeve.
The valve seat is designed as a further, separate component and serves at the same time as a carrier for the valve spring and the holding element. In another known exemplary embodiment, the valve spring is designed as a corrugated hose and its ends are held in the holding element of sleeve-shaped design and the valve seat of sleeve-shaped design, respectively. It has been found here that the depressions in the wall of the corrugated hose, the ends of which are held in the sleeve-shaped holding element and in the sleeve-shaped valve seat, form dead spaces and, as a result, dirt-collecting gaps which may have a disadvantageous effect on the medium to be carried in the hose lines. Moreover, when using high-purity chemicals as the medium to be transported, no metal parts must come into contact with the chemicals since, otherwise, the chemicals will be contaminated by metal ions. If such contaminated chemicals were used for the production of electronic components, this would give rise to problems since the metal ions are released to the electronic components and thereby contaminate these components.
DE 30 50 957 C2 and DE 36 18 233 C2 disclose shut-off valves in which the valves springs of the valve insert are in the form of a bellows. It has been found here that the bellows succumbs gradually to fatigue and is therefore suitable only to a limited extent as a spring since the restoring force gradually weakens. In addition, the bellows has only a low spring constant.
On the basis of DE 30 50 957 C2, the object on which the invention is based is to further develop a hydraulic shut-off valve of the type stated at the outset in such a way that the valve insert raises fewer problems, particularly in the area of high-purity chemicals.
According to the invention, this object is achieved by virtue of the fact that the cavity is closed in gas-tight fashion by means of a screw plug or by means of a cover which is welded on or welded in.
The valve insert according to the invention has the advantage that it has a higher spring constant and can be produced with smaller tolerances. Moreover, no dead spaces arise.
The gas-tight closure of the cavity provides the advantage that, when the spring is compressed, the enclosed gas volume in the cavity is likewise compressed and produces a restoring force in the direction of the spring force. This restoring force stemming from the enclosed gas volume counteracts slackening of the spring, and the spring constant of the valve insert according to the invention or of its valve spring is thus constant over a long period. In addition, the gas volume enclosed in the cavity raises the spring constant, making it possible to use as the spring material even materials which have a low modulus of elasticity.
According to the invention, the valve insert is provided in a coupling sleeve and a coupling nipple of a hose coupling. Here too, the installation of the valve insert in the sleeve and the nipple is considerably simplified.
To assist the spring force of the valve insert and of the compressed gas volume, a further element composed of a suitable material, preferably however of plastic, can be additionally inserted in the cavity of the valve insert. If the auxiliary spring installed in the cavity of the valve insert has a spiral shape, it must be coiled counter to the direction of screwing in of the valve insert. This prevents loosening of the valve seat in the valve housing due to the actuation of the coupling.
In conventional coupling designs, it is generally assumed that the spring characteristics of the spring elements are approximately the same in both parts of the coupling, namely the coupling sleeve and the coupling nipple, and also do not change or at least change in the same manner during the period of use. This is the pre-requisite for the ability to open the valves of the two parts of the coupling in an optimum manner when the said parts are brought together. If the spring characteristics are different, due, for example, to premature fatigue of one of the two spring elements, there is the risk that one valve will be opened only incompletely or not at all. As a result, the rate of flow in the coupling system will be restricted to a greater or lesser degree or passage will be completely interrupted.
In the present invention, the possibility of such faults can be eliminated by the additional installation of a distance pin in the valve seat. The distance pin can either be inserted loosely into the housing or be connected to the outer housing in a fixed manner.
According to a preferred embodiment, the valve spring is formed by a bellows or a corrugated hose. Here, the bellows has an undulating wall. In another exemplary embodiment, the bellows has a zig-zag wall. By virtue of the configuration of the wall as an undulating wall or in a zig-zag shape, the spring constant can be influenced in a specific manner, undulating walls being used for a high spring constant and zig-zag walls for lower spring constants. The spring constant can be further increased by a shallow undulation or zig-zag.
In another exemplary embodiment, the valve spring is formed by a coiled spring.
According to the invention, the valve insert is produced by machining or by injection-moulding. In this case, the valve seat has an actuating nose for the other valve insert on its side remote from the valve spring. As the coupling nipple is coupled to the coupling sleeve, this actuating nose rests on the valve seat of the other valve insert and raises it from the sealing surface as the coupling nipple is pushed further into the coupling sleeve. At the same time, however, the valve seat together with the actuating nose also rises from the sealing surface, with the result that the two hose ends are then connected to one another and the medium to be transported can pass through the two valves unhindered. The opening gap can be set to a specific size by means of the length of the actuating nose.
According to a preferred exemplary embodiment, the valve insert is composed of plastic, especially a fluoroplastic such as PFA, PTFE, TFM, PEEK etc. Such plastics are used particularly when high-purity chemicals have to be transported. If the valve spring has a gas-tight cavity, such plastics can be used without reservations since the spring constant of such plastics is raised to such an extent by the enclosed gas volume and, furthermore, the plastic shows no signs of fatigue due to the restoring force provided by the enclosed gas volume that the properties are comparable to those of metal springs.
The valve insert according to the invention of a hydraulic shut-off valve are preferably used in hose couplings for the connection of hose lines in which high-purity chemicals are transported. The novel valve insert proves to be particularly advantageous particularly where this is the intended use since its properties correspond to those of a valve insert with a metal spring but the risks which arise with
Benzinger Martin
Buttner Werner
Szeteli Andreas
Chambers A. Michael
Merck Patent Gesellschaft mit beschrankter Haftung
Millen White Zelano & Branigan P.C.
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