Fluid handling – Removable valve head and seat unit – Threaded into valve casing
Patent
1990-07-13
1991-11-12
Cohan, Alan
Fluid handling
Removable valve head and seat unit
Threaded into valve casing
137489, 251334, 251363, 251364, F16J 1506
Patent
active
050639617
DESCRIPTION:
BRIEF SUMMARY
From the prospectus No. 5.202.0/3.87 of the firm of Flutec, D-6603 Sulzbach/Saar, "Directional Seat Valves WSE 2", it is known to screw a cartridge-type valve housing containing a two-way seat valve into the stepped borehole of the supporting body designed as a block or housing, in which various channels of the hydraulic system and pipe connections are arranged. The stepped borehole has three cylindrical sections mutually offset axially by conical shoulders and is prolonged by a pump channel extending in the direction of the borehole axis. The valve housing has matching cylindrical sections, two of which have annular grooves in which an O-ring is fitted. The sections and the conical diametral steps of the stepped borehole require precision finishing of their surfaces, and, in addition, special attention must be paid to the fact that the sections and the diametral steps are coaxial with the borehole axis. The precision finishing is necessary not only with regard to the sealing effect of the O-rings but also for avoiding any damage which may be caused to said O-rings when the valve housing is inserted and screwed in position. In addition to this high manufacturing expenditure and the comparatively complicated assembly, the valve housing requires a comparatively large installation length so that it cannot be installed in thin-walled piston bases, cylinder bases or housing walls. A special disadvantage of this connection principle is that inaccuracies caused by the manufacturing process, which will cause leakage of the connection, will result in a very high reject rate of the housings or blocks defining the supporting body, said housings or blocks being precisely the most expensive components of the hydraulic system. A secondary treatment of a reject housing or block is hardly possible, since the sealing effect can then no longer be achieved. Repairs of a housing or of a block within which leakage occurs in the stepped borehole are hardly possible either.
In the pilot controlled check valve known from German-pat. 28 05 040, which is screwed into a tapped borehole, an O-ring surrounded on at least half of its periphery by a shoulder of the valve housing is placed against the conical diametral step of the stepped borehole. The circumferentially extending supporting rib, which grips the O-ring, is pressed against the diametral step so that the O-ring cannot flow under the hydraulic pressure subsequently exerted on it. Exterior sealing of the stepped borehole is guaranteed by the interlocking screw threads of the stepped borehole and of the valve housing, another external seal which is clamped down by a screw-in head at the outer end of the valve housing being used, if necessary. Also this principle requires complicated precision finishing of the inner wall of the stepped borehole and of the diametral step so as to avoid damage which may be caused to the O-ring during insertion. If leakage occurs at the diametral step which cannot be remedied by changing the O-ring, the diametral step can only be subjected to a secondary treatment in cases in which the valve housing has not been screwed in with a screw-in head limiting its depth of insertion, since otherwise the O-ring cannot be sealingly repositioned. High reject rates due to manufacturing inaccuracies also occur in this case.
The present invention is based on the task of providing a connection of the type mentioned at the beginning, which is less expensive to manufacture, easy to assemble and easy to repair and which is characterized by a small insertion length for the valve housing. The manufacturing costs are to be cut by a reduction of the reject rate of the housings or blocks as a result of less stringent requirements in regard to precision.
In accordance with the present invention, the posed task is solved by the features disclosed in the characterizing clause of patent claim 1.
Due to their deformability, the soft metal rings, which are cold-formed between the respective support surface and the diametral step by means of the thread tightening tension and w
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patent: 3903919 (1975-09-01), Zeuner
patent: 4078574 (1978-03-01), Kosarzecki
patent: 4505287 (1958-03-01), Blaedel
patent: 4781325 (1988-11-01), Finders
Cohan Alan
Heilmeier & Weinlein Fabrik fur Oel-Hydroaulik GmbH & Co.
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