GB1418993A - Diaphragm pump particularly for the generation of vacuum - Google Patents

Abstract

1418993 Diaphragm pumps for vacuum production E BECKER 16 Feb 1973 [8 March 1972] 7794/73 Heading F1N A diaphragm pump for vacuum production comprises a diaphragm 2 having a thickened relatively inflexible spherically convex control portion 8, a housing surface 4 facing the diaphragm and having a spherically concave control portion with a radius of curvature the same or slightly exceeding the curvature R2 of the convex portion 8, and a connecting rod 3 secured to the diaphragm and arranged cyclically to move the diaphragm to a position in which it makes substantially overall surface contact with the inner surface 4. The connecting rod 3 is oscillated by a crank drive and is secured to the central portion of the dia- phragm 2 by a metal member 26 vulcanized to a hub-shaped projection 9 of the diaphragm. The pivot axis of the connecting rod 3 is also the centre of curvature of the spherically convex central portion 8. To assist in preventing the diaphragm from bowing away from the surface 4, the crank-case K may be maintained at a pressure above atmospheric. Thus the crank-case K may be connected to an external source or be provided with a suction valve 12 and a valve 13 which allows the discharge of air when the pressure in the crankcase exceeds a certain value. The central portion of the surface 4 is either surrounded by a conical outer portion or, on the side of the surface 4 adjacent a delivery port 11, the conical surface is replaced by a convex surface (4'). A stiffening member (23) may be disposed within the central portion 8. The central diaphragm portion 8 may be harder than the surrounding annular portion 21. Two or more pumps as described above may be combined, Fig.6 (not shown) to form a two or multi-stage pump.