| 摘要 |
974,812. Screw and nut gearing; valves. YARNALL-WARING CO. March 7, 1961 [March 11, 1960], No. 8208/61. Headings F2Q and F2V. In mechanism producing linear motion of a member, such as a valve stem 15, in a sealed housing by rotation of an external member such as a handwheel 46, the stem 15 is surrounded by a flexible non-rotatable sealing tube 21, e.g. of stainless steel, whose upper end is closed by a plug 22, whose lower end is welded to the valve body 10, and whose inner surface is provided with a screw thread or with rings 35 eccentrically engaging a part of the periphery of a smaller diameter screwthread 34 on the stem 15, relative linear movement being obtained by gyrating the non- rotatable tube 21 at two or more points in its length so that the points of engagement between the threads 34, 35 are progressed around the circumference of the stem 15. As shown, the gyrating or flexing is obtained by securing the tube 21 to the inner races of two bearings 39, 40 whose outer races are eccentrically secured in a rotatable casing 43 which carries the hand wheel 46 and is mounted in bearings 48, 52. The interengaging screw threads 34, 35 may be of the same or opposite hand and one of them may have a zero helix angle, i.e. comprise the rings 35 shown. In a modification the tube 21 is gyrated by three eccentric bearings in a rotatable casing. In a further modification the tube is flexed to a helical formation by a series of closely spaced eccentric bearings to provide a continuous helical contact path between the screwthreads. In an alternative arrangement, Fig. 6 (not shown), the valve stem is hollow and has an internal thread partly engaged by rings on the exterior of a non-rotatable flexible tube of smaller diameter, the tube being flexed by a rotatable S-shaped rod mounted therein and secured to an operating hand wheel. The valve shown comprises a disc 14 removably secured to the stem 15 by a key 32 engaging a keyway in a fixed guide 25, the body 10, tube 21 and guide 25 being secured together by welded connections.
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