Pump pressure and flow volume regulating apparatus

Claim 1

Pump pressure and low volume regulating apparatus, comprising, in combination, a stator having an oblong inner cavity; a cylinder block located in said cavity and mounted on said stator for rotation about an axis, said cylinder block having cylinder chambers and pistons reciprocable in said cylinder chambers; actuating ring means located in said oblong inner cavity surrounding said cylinder block and having an endless eccentric inner surface for reciprocation of said pistons whereby said cylinder chambers expand and contract, and an endless outer surface forming in said oblong cavity two diametrically opposed regulating chambers symmetrical to an axial plane, said actuating ring means being mounted in said stator for adjusting movement in said plane for varying the eccentricity of said endless inner surface, and thereby the stroke of said pistons and the volume of the pumped fluid; spring means biasing said actuator ring means to move in one direction in said plane so that the volume of one of said regulating chambers is normally greater than the volume of the other regulating chamber so as to obtain a great eccentricity of said endless inner surface and a great pumped volume of fluid; inlet conduit means for supplying fluid to expanding cylinder chambers, and outlet conduit means for discharging fluid from contracting cylinder chambers; control conduit means connecting said outlet conduit means with said other regulating chamber; pressure-responsive control valve means between said outlet conduit means and said control conduit means normally closing said control conduit means, and responding to a selected maximum pressure in said outlet conduit means to open so that high pressure fluid from said outlet conduit means is supplied to said other regulating chamber for moving said actuating ring means opposite to said one direction against the action of said spring means until the pUmped volume, and the pressure in said outlet conduit means, control conduit means, and other regulating chamber are reduced so that said control valve means closes, and said spring means moves said actuating ring means again in said one direction for increasing the pumped volume and the pressure in said outlet conduit means, said control valve means including a spring biased pressure limiting valve responsive to a high selected pressure and located in said control conduit means between said outlet conduit means and said other regulating chamber, and a spring biased bypass valve in said control conduit means downstream of said other regulating chamber, and being responsive to a substantially lower predetermined pressure than said pressure limiting valve so as to connect said control conduit means with a low pressure region.