The valve has a cylindrical, cartridge-like housing in which a piston is slidably disposed. The piston subdivides the housing into an outer chamber, at one housing end, into which oil under pressure is admitted, and an inner chamber from which oil is discharged. Ports formed in the housing open onto the inner chamber and allow the oil to pass therethrough and on into an associated air compressor. The other end of the valve housing defines a control chamber. The piston has a depending, cylindrical shank which (a) moves into, and removes from, the control chamber, and (b) has a disc, fixed onto the end of the shank, which is sealingly engaged with the wall of the control chamber. Channels are formed in the periphery of the piston, to allow oil to flow from the outer chamber to the inner chamber, but a land in the housing defines a seat for the piston which, when the piston closes thereupon, interdicts the aforesaid oil flow. A pilot, compressed air supply, tapped off from the compressed air discharge line of the associated air compressor, is admitted into the control chamber to displace the disc and unseat the piston. In the absence of the pilot supply then, as when the air compressor is shut down, the oil pressure in the outer chamber seats the piston, sealingly, on the land.
A four-way fluid valve combines direct solenoid operation of one port with pilot valve operation of a second port and a common exhaust port, all of the ports being located in the valve body. Direct valve operation is achieved by a magnetically operated plunger carrying a normally closed valve element and operable to move a separate valve holder carrying a normally open valve element. A pilot operated valve disc is supported at the inlet port for axial movement to inlet or exhaust positions in response to inlet pressure or a pilot-operated piston.
A rotary compressor in a cooling or a heat pump system which is provided with an oil injector and includes an oil separator on the high pressure side of the system. Oil is returned to the compressor for lubrication, cooling and sealing and is normally caused to circulate by means of the natural pressure differences in the cooling system. When the pressure level is too small to provide sufficient oil circulation, an oil pump is connected. By employing a pressure controlled regulating valve in the system, which serves both as a pressure regulating and a flow regulating valve, the oil pump may be caused to run idle when a sufficient pressure difference has been attained in the system.
A low pressure drop valve connectible to a source of pressurized hydraulic fluid for modulating hydraulic fluid flow is provided; it includes a valve body defining an axially extending tapered bore and having hydraulic flow inlet and outlet ports, a plug valve movable axially in that bore and having an externally tapered surface facing the tapered bore and movable axially relative thereto to increase or decrease a gap formed between the tapered surface and the tapered bore, for controlling the flow of hydraulic fluid via the gap and at least one of said ports, and apparatus responsive to a side stream of pressurized hydraulic fluid to control axial movement of the plug valve in the tapered bore, including first and second pistons connected with the plug valve to move axially therewith, the valve body forming first and second cylinders respectively receiving the pistons for application of hydraulic fluid pressure to the pistons for displacing the pistons and plug valve axially, and protective O-rings in the cylinders acting to space the pistons from bores formed by the cylinders.
A variable oil flow regulator for minimizing noise generated typically by an oil-injected rotary screw compressor when the compressor transitions from an on-load mode for compressing fluid to an off-load mode. The regulator includes a housing having a first end, a second end and a chamber formed therein extending between the first and second ends. The regulator also includes a first port formed at the first end of the housing for admitting a pressure signal into the chamber corresponding to a compression level of the fluid, a second port formed at the second end of the housing for admitting the oil into the chamber, and a third port formed in the housing between the first and second ends of the housing for discharging the oil admitted into the chamber through the second port. The regulator further comprises a piston slidably disposed in the chamber between the first and second ends of the housing, the piston having a first end in fluid communication with the pressure signal and a second end in fluid communication with the oil. The piston is movable into a first position for allowing unrestricted flow of the oil between the second and third ports when the compressor is in the on-load mode and into a second position for restricting flow of the oil between the second and third ports when the compressor is in the off-load mode, the position of the piston being dependent upon the pressure differential between the pressure signal and the oil.
