Ring cam and fluid-working machine including ring cam

摘要

A ring cam for a fluid-working machine is formed from a plurality of segments. The segments comprise a leading cooperating formation which has a piston facing surface which forms part of the working surface, at a trailing end, and which is recessed from the working surface at a leading end, and a trailing cooperating formation which has a piston facing surface which forms part of the working surface at a leading end, and which is recessed from the working surface at a trailing end. The segments having piston facing surfaces which are in compressive stress such as to partially or fully compensate for tensile stress arising from the action of rollers in use. The segments form a wavelike cam surface and attachment means are provided, through the working surface, on whichever of the leading or trailing surfaces thereof is subject to lowest forces from pistons in use.

主权项

1. A fluid-working machine comprising:
a ring cam, having a working surface, and at least one piston, at least one respective cam engaging element and at least one respective working chamber, and wherein the ring cam comprises at least two segments;
each said segment having a leading cooperating formation at a leading region, and a trailing cooperating formation at a trailing region; each leading cooperating formation in cooperative engagement with said trailing cooperating formation of an adjacent segment of said at least two segments at an interlocking region; each said segment having a piston facing surface,
the cam working surface being a portion of the piston facing surfaces which operatively engages with the at least one piston by way of said at least one respective cam engaging element so as to couple reciprocating motion of the at least one piston to rotation of the ring cam relative to the at least one piston;each said leading and trailing cooperating formation having a portion of the piston facing surface; wherein across each interlocking region, a portion of the piston facing surface at the leading cooperating formation forms a part recessed from the working surface of the trailing cooperating formation, and a portion of the piston facing surface at the trailing cooperating formation forms a part recessed from the working surface of the leading cooperating formation.