GB1454140A - Reciprocating compressors - Google Patents

Abstract

1454140 Compressors; inlet and outlet valves W W PAGET 29 April 1974 18577/74 Heading FIN [Also in Division F2] A two stage compressor has an inlet and discharge valve arrangement at the end of each cylinder and each arrangement includes a valve-member which is associated with a part which limits the amount it lifts when open. In a first construction, an annular series of openings 34 in a first valve seat 33 is closed by an annular inlet valve plate 35 and an annular passage between the first seat 33 and a second seat 28 is closed by an annular outlet valve plate 45. The inlet valve plate 35 has diametrically opposed projections 36 and 37 which are received in recesses 38, 39 respectively of a part 31. The recesses 38 hold the valve plate so that it flexes about a line passing through them until the projections 37 abut against the bottoms of their recesses 39 and therby limit valve lift. The outlet valve plate 45 has a pair of similar projections which are received in two recesses in a boss on a cylinder head 24 and which also define a line about which valve plate 45 flexes to open. Lift of plate 45 is limited by an annular backing member. 50 which has two diametrically opposed projections 51 (Fig. 13) located in the two recesses on the boss and which is bent about a line through its projections to curve away from the valve plate 45. Consequently valve plate 45 gradually spreads on to the backing member 50 as it opens or lifts. The annular passage closed by the valve plate 45 may be replaced by an annular series of apertures similar to 34. In a further modification in which an annular inlet valve plate surrounds an annular outlet valve plate, Fig. 15 (not shown) the inlet and outlet valve plates both have backing members. Each valve plate has three equi-angularly spaced notches in its outer periphery and a dowel is located in each notch. The associated backing member is shaped to press the valve plate against its seat at the location of each dowel and so each valve plate flexes between the dowels, upon opening, into contact with its backing member. Varying Capacity: Each cylinder has a liner 13, 17 and each liner has an annular series of openings 18, 19 communicating with respective inlets 11 and 15. For each cylinder there is provided a set of liners with the opening in each one at a different axial location. Consequently the capacity of the compressor is determined by when the piston passes beyond the series of openings. The liners may be made of graphite polyimide or P.T.F.E. and the outer surfaces of the pistons may be hard chrome plated or made of aluminium.