Valves and valve actuation – Mechanical movement actuator – Screw
Patent
1997-01-06
1998-11-03
Walton, George L.
Valves and valve actuation
Mechanical movement actuator
Screw
137375, 744248, 251284, 251326, 251330, F16K 3150
Patent
active
058297340
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a shut-off valve comprising a valve housing provided with a flow passageway and a shut-off member arranged in said housing and displaceable by means of an actuator device of the stem
ut type between a position, in which the flow passageway is open and a position, in which it is closed, said actuator device comprising a nut member provided with an internal thread with a first pitch, and an outer stem member provided with an external thread engaging the internal thread of the nut member, first coacting stop means being provided between the outer stem member and the nut member, said stop means adapted to engage each other at the end of the closing movement to ensure a joint turning of the two members in relation to the third member during the final part of the closing movement.
TECHNICAL BACKGROUND
A screw
ut device is known from FR 871.203, in which one and the same stem on a first portion is provided with a thread with a large pitch for rapid travel, and on a second subsequent portion is provided with a thread with a small pitch for a more slow travel with great force. In order to engage in both threads, the nut member of this special stem has to comprise a number of projections instead of a conventionally screw thread. Such a nut member is difficult to manufacture and the stress on the individual projections is heavy. Moreover, two successive threads are bulky.
SE-B-385.952 discloses an actuator device of the screw
ut type comprising a threaded stem, upon which a stem nut is arranged having an internal thread engaging the stem and an external thread engaging an outer sleeve. Jointly with damping means, the stem nut is adapted to ensure a springy and damping stop function at the end of the movement of the stem.
Furthermore, U.S. Pat. No. 4,488,704 discloses a valve provided with an actuator device comprising a nut member having an external thread interengaging a mounting member connected to the valve housing. Moreover, the actuator device comprises a stem, at which lower end a shut-off member is arranged, said stem being provided with an external thread engaging an internal thread of the nut member. The nut member as well as the stem is provided with an operating handle. In the shown embodiment, the external thread of the nut member is more fine than its internal thread engaging the stem. As a result, a rapid movement of the shut-off member is obtained, when the handle of the stem is operated and a more slow and accurate movement of the shut-off member is obtained, when the handle of the nut member is operated. Owing to consideration of space and control, however, this valve is not particularly advantageous in that two operating means or handles are required.
DE-A1-4101075 discloses a valve of the type stated in the introduction. The outer nut member of the actuator device is arranged pivotally in relation to the valve housing and driven by means of a handle, whereas the inner stem member is fixed to the shut-off member. The outer stem member engages the outer nut member as well as the inner stem member by means of a coarse and a fine thread, respectively. During closing and opening of the valve, both the outer and the inner stem member is displaced in relation to the housing.
BRIEF DESCRIPTION OF THE INVENTION
The object of the present invention is to provide a shut-off valve of the type stated in the introduction, whereby a reliable sealing in the closed position at a lower closing torque than at known shut-off valves and still in keeping with the norms for the maximum number of rotations from open to closed position and without the drawbacks stated above.
The shut-off valve according to the invention is characterised in that the inner stem member is arranged rotatably, but not displaceably in relation to the valve housing and provided with an end portion projection out therefrom and adapted to be connected with a driving means, and that the nut member is secured to the shut-off member being provided with a cavity for receiving the outer stem member and t
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patent: 5279320 (1994-01-01), Freudendahl
Aage V. Kjaers Maskinfabrik A/S
Walton George L.
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