Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2000-07-12
2001-12-04
Fox, John (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C137S625300
Reexamination Certificate
active
06325101
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a choke valve comprising a choke body able to be set in the direction of its longitudinal axis and which in a manner dependent on its position (choking position) between an inlet and an outlet makes available a smaller or larger flow aperture.
THE PRIOR ART
Known choke valves of this type, as described for instance in the textbook “Einfühurng in die Pneumatik”, Meixner/Kobler, page 132, possess a spherical choke body, which in manner dependent on the choke setting plunges to a greater or less extent into an opening and so makes available varying apertures for the respective fluid medium. The choke body is rotatably mounted on the valve housing by means of a screw thread and its axial position or, respectively, choke setting may be varied by rotation.
A substantial disadvantage of such spherical choke bodies is the non-linear setting characteristic. The aperture as a rule varies in a square law function in relation to the change of the axial position of the choke body so that it is extremely hard to find reproducible settings. A further disadvantage is that thread play between the choke body and the valve housing leads to slight pendulum movements of the choke cone on resetting the choke. This in turn leads to irregular variations in the aperture and to a still further impairment of setting operations.
SHORT SUMMARY OF THE INVENTION
One object of the invention is to provide a choke valve of the type initially mentioned with which leads to a linear characteristic and makes possible extremely exact, reproducible settings.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present invention the choke body possesses a cylindrical choke piston, which in every choke setting plunges coaxially into an inlet flow duct communicating with the inlet, said choke piston being in constant sealing contact at a peripheral seal area with the wall of the inlet flow duct, the axial position of the seal area assumed in relation to the inlet flow duct being dependent on the instantaneous choke setting and outlet ducts are provided in the wall of the inlet duct on the one hand communicating with the outlet and on the other hand opening via transfer openings, which are distributed along the setting stroke of the seal area, into the inlet duct, the aperture being defined by the cross section, which is made available toward the upstream section of the inlet flow duct, of the transfer openings.
The part of the choke body responsible for the aperture made available is now no longer spherical in form but constituted by a cylindrical choke piston constantly plunging into an inlet flow duct communicating with the inlet. The seal area present between the choke piston and the inlet flow duct wall then prevents pressure medium supplied through the inlet flow duct flowing past the choke piston. Consequently it is only possible for the pressure medium to flow away via the transfer openings, provided in the inlet flow duct wall upstream from the seal area toward the upstream section of the inlet flow duct. Dependent on the particular setting of the choke the total aperture-defining cross section of the transfer openings communicating with the upstream section of the inlet duct, may be preset to varied amounts. By a suitable selection of the design and arrangement of the transfer openings it is then possible to produce a linear setting characteristic in an extremely simple manner. Since, unlike the case of the prior art, the aperture is not in essential respects preset by the annular gap surrounding the choke body, furthermore any irregularities in the axial position of the choke piston are not disadvantageous. Moreover owing to the seal area it is possible to prevent significant leakage past the choke piston so that so that any danger of a pendulum movement is prevented at the outset. In this respect owing to the cooperation of the choke body and the inlet flow duct wall at the seal area it is also possible to achieve a guiding effect having a favorable effect on the positional stability of the choke body.
Further advantageous developments of the invention are defined in the claims.
The outlet flow ducts can be at least partly constituted by separate ducts similar to drilled holes and/or have a slot-like configuration. The individual ducts may be so placed that their transfer openings directed into the inlet flow duct lie on a helical path along the periphery of the inlet flow duct.
Moreover the outlet flow ducts may also be at least partially formed by the intermediate spaces or interstices of a porous inlet flow duct wall. The latter may for instance be produced by the use of a sintered metal or of a plastic material provided with fine interstices.
The choke valve may additionally be provided with an integrated check valve so that all in all a combined choke and check valve is produced. The valve member of the check valve may for instance be in the form of a lip seal and be more especially borne by the wall of the inlet flow duct.
The wall of the inlet flow duct may readily be an integral part of the valve housing of the choke valve. However, it is particularly convenient to fashion the inlet flow duct wall as a component of a valve cartridge, which may be fitted in any suitably adapted housing provided with an inlet and an outlet. This renders possible extremely simple integration of the choke valve in the housing of any fluid power equipment, for instance fluid power drives.
The choke body may be fixed in position by means of a screw thread so that it is turned for changing the setting of the choke, this simultaneously resulting in a shift in the axial position. However as a more advantageous design a structure actuating means is proposed in which the rotary actuating member is arranged to be rotatable and is simultaneously locked axially, whereas the choke body is prevented from rotating and is able to be moved axially, there being a threaded engagement between the rotary actuating member and the choke body. Turning of the rotary actuating member results in this case in a purely translatory movement of the choke body, the axial position of the rotary actuating member remaining unchanged. This means that, irrespectively of the setting made, there are extremely compact dimensions. Furthermore such a structure makes it easier to adopt features, which render possible a digital setting characteristic of the choke valve. Thus detent means can be provided for detachable attachment of the rotary actuating member in different angular positions, the selection grid pitch bearing a direct linear relation to the aperture set by the choke piston.
Further advantageous developments and convenient forms of the invention will be understood from the following detailed descriptive disclosure of embodiments thereof in conjunction with the accompanying drawings.
REFERENCES:
patent: 4041982 (1977-08-01), Lindner
patent: 5090450 (1992-02-01), Pelech et al.
patent: 5113908 (1992-05-01), Steinke
patent: 5141028 (1992-08-01), Cohen
patent: 5261453 (1993-11-01), Hekkert et al.
patent: 5337784 (1994-08-01), Grubb
patent: 5351717 (1994-10-01), Saito
patent: 5427147 (1995-06-01), Henriksson
patent: 5516079 (1996-05-01), Baumann
patent: 39 03 781 A1 (1990-08-01), None
patent: 197 48 343 A1 (1999-05-01), None
patent: 1291716 (1962-03-01), None
Kees Ulrich
Stoll Kurt
Festo AG & Co.
Fox John
Hoffmann & Baron , LLP
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