Patent GB-886810-A (GB)
Title: Improvements in or relating to valve devices for the control of fluids
IPC: F16K31/44
Filed: 1958-05-30
Abstract: 886,810. Screw-and-nut mechanism; toothed gearing. UNITED SHOE MACHINERY CORPORATION. May 30, 1958 [May 31, 1957], No. 17270/58. Classes 80 (1) and 80 (3). [Also in Group XXIX] A valve comprises a flexible tube housing one or a pair of movable closure members actuable by deformation of the tube from its circular cross-section. In one embodiment a pair of closure members 22, 23, Fig. 5, form a cylinder with a closed end and are movable axially in opposite directions to separate mating, diametral surfaces 46 to permit the passage of fluid. The surfaces 46 are cut obliquely so that as the valve is closed the members are pressed outwardly to form a seal with a tube 50 mounted within the flexible tube 20<SP>1</SP>. The members 22, 23 are formed with external screw-threads of opposite hand adapted to mesh with a thread-like formation 21 in the tube 50. A hand wheel 35, restrained against axial movement, is rotatably mounted on the tube 20<SP>1</SP> and is so shaped internally as to deform the tubes 20<SP>1</SP>, 50 so that the thread-like formation 21 meshes with the threads on the members 22, 23 at certain regions only. In the example shown the hand wheel has a bore resembling an eclipse so that meshing takes place only at diametrically opposite regions, and, as described in Specification 878,948, the number of starts of the threads on the members 22, 23 differs from that of the formation 21 by the number of regions, or a multiple of the number of regions at which meshing occurs so that rotation of the hand wheel causes axial movement of the members 22, 23 in opposite directions. As shown, the formation 21 consists of individual rings which do not form a helix and the threads on the members 22, 23 are each of two-start form. Rollers 37, which may be cylindrical or barrel-shaped, are interposed between the hand wheel 35 and the tube 20<SP>1</SP>. Alternatively, the rollers may be omitted in which case the surface of the hand wheel that engages the tube 20<SP>1</SP> is made convex in longitudinal section. The hand wheel may be split diametrically to facilitate assembly. In a modification, the flexible tube 50 may be omitted, the formation 21 being carried by the tube 20<SP>1</SP>. Also, a guiding tube 57 fixed at 60 to the member 22 is omitted and the members 22, 23 are guided relatively to each other by interengaging tongue-and-groove formations. The members 22, 23 may be formed with streamlined surfaces to facilitate flow past the closure surfaces 46. Fig. 11 shows an arrangement in which a single closure member 67 coacts with a seat 68 at one end of the flexible tube 20<SP>2</SP>. The valve components may be made of steel, stainless steel, bronze, titanium alloy, &c., or rubber, synthetic rubber, nylon, &c. A construction for actuation by an electric motor 114, Fig. 13, has a flexible tube 20 with an internal thread-like formation coacting with threads 24, 25 on valve members 22<SP>1</SP>, 23<SP>1</SP> that are slidable in opposite directions and guided by a tube 83 welded to one end of the tube 20 and carrying a Woodruff key 84 engaging a slot 86 in the member 23<SP>1</SP> to prevent rotation of the members 22<SP>1</SP>, 23<SP>1</SP>. When closed the members 27, 28 press outwardly against a tube 95 secured to the other end of the tube 20. The motor is geared to a ring 105 which receives an outer race 108, rollers 107, and an inner race 106. The outer race is of varying thickness so that the inner race is deformed to a non-circular shape to cause corresponding deformation of the tube 20. A flexible gear 122 carried by a sleeve 123 fixed at 125 to the valve housing encircles the tube 20 and follows the deformation of the latter. The gear 122 meshes at diametrically opposite points with an internal ring gear 118 fixed to the motor housing whereby, as described in Specification 790,171, the ring gear together with the motor and housing 102 is caused to turn about the tube 20. An indicator 126 co-operates with markings 127 on the tube 20 to indicate the degree of opening of the valve. The motor is connected in circuit with two limit switches of which one de-energizes the motor when the valve is fully open and the other places a resistor in series with the armature of the motor to reduce torque as the valve approaches closure. The increase in load on the motor as the valve closes causes a relay to interrupt the circuit.