GB846023A - Improvements in camming assemblies, more particularly for closures for pressure vessels - Google Patents

Abstract

846,023. Closures for resisting fluid pressure. VISCHER, A. July 3, 1957 [July 31, 1956], No. 21054/57. Class 123(1) [Also in Groups XXIV and XXV] In a pressure vessel closure, e.g. of the form described in Specification 521,673, .which consists of a flexible disc 18, for example of stainless steel, which is prestressed to a warped shape of elliptical projection allowing it to be inserted into the opening in a vessel 14 and which has an operating device whereby a pull can be exerted at the centre of the disc to cause it to assume an unwarped shape projecting a circular form with its outer edge 18a in sealing engagement with a gasket 16 held in an inturned lip 14a defining the rim of the opening, the operating device provides for an initial force to be exerted to move opposite edges of the warped cover into engagement with the gasket and then for a much greater force to flex the cover to its unwarped operative condition. The operating device consists of a camming assembly 20 which bears on a cross-brace 22 pivoted to the vessel supporting structure 11 at 26 and serving as a hinge support for the cover 18. The assembly 20 which is preferably made of a heat-resistant, plastic material, consists of an operating handle 20a provided with an initial effort camming surface 30. The second or high force applying portion of the assembly comprises a circular ring 32 which is rotatably journalled on needle rollers 36 on an inner race 34 supported in the arm 20a. The centre of the cover 18 is connected to a pin 64 passing through the arm 20a and inner race 34 by a U-shaped yoke 56 the arms of which pass through slots in the brace 22, a compression spring 61 being provided between the cover and the brace to force the brace to ride firmly on the camming assembly 20. In operation, to close the vessel, the disc 18 in its warped shape is passed through the opening as the brace 22 hinges to the position where it contacts a stop bracket 25. The handle 20a is now turned about the pin 64 to the position shown in Fig. 4, the cam surface 30 contacting the brace as the pin moves outwardly to seat opposite disc edges 18 on the gasket 16. Further rotation of the handle to the position shown in Fig. 5 flexes the disc 18 to its circular form, this rotation being facilitated in spite of the increased pull required as the ring 32 contacts the brace and the inner race 34 revolves in its frictionless bearing. When the vessel is pressurized the handle 20a is returned to the Fig. 4 position, the disc 18 being held in its circular sealing form by the pressure. In this way when the pressure operation, e.g. cooking or sterilizing is complete and the pressure is lowered almost to atmospheric the cover 18 will snap back to the warped shape notifying the operator that the vessel may be fully opened.