Rotary control valve for screw compressors

Claim 2

In a helical screw gas compressor: a casing having two parallel intersecting bores; an inlet port and a discharge port opening into said bores; interengaged helical screw rotors disposed in said bores and characterized by cooperating helical grooves and lobes forming working chambers operable to entrap and compress gas admitted to said bores through said inlet port; a cylindrical chamber formed in said casing and having an opening in communication with said inlet port; a plurality of auxiliary ports formed in said casing and opening to at least one of said bores and to said chamber, said auxiliary ports being spaced apart axially with respect to the longitudinal axis of said one bore; a rotatably turnabLe control valve member disposed in said chamber characterized by a portion forming a closure for said auxiliary ports delimited by a control edge coactable with said auxiliary ports for opening and closing said auxiliary ports in response to turning said valve member whereby the gas throughput of said compressor is controlled in accordance with the opening and closing of said auxiliary ports by said valve member; means for turning said valve member; and, passage means for injecting liquid into said bores for mixing with said gas being compressed by said rotors, said passage means being operably associated with said valve member whereby the effective fluid flow area of said passage means is increased in response to the turning of said valve member to close said auxiliary ports.

Claim 3

The invention set forth in claim 1 wherein: said passage means for injecting liquid into said bores is disposed in said casing and is operable to control the axial position of liquid injection with respect to the longitudinal axis of said bores in accordance with the opening and closing of said auxiliary ports by said valve member.

Claim 4

The invention set forth in claim 2 wherein: said passage means for injecting liquid into said bores is movably disposed in said casing for injecting liquid into a working chamber formed by a pair of grooves of said rotors only after said working chamber is no longer in communication with said inlet port.

Claim 5

The invention set forth in claim 2 wherein: said valve member comprises a cylindrical plug portion closely fitted in said chamber and delimited by said control edge, and said passage means comprises plural passages in said cylindrical plug portion operable to be in communication with said auxiliary ports in accordance with the rotative position of said valve member for injecting liquid into said bores.

Claim 6

The invention set forth in claim 4 wherein: said passages in said valve member are spaced apart axially with respect to the rotational axis of said valve member and said passages are spaced apart around and open to the circumference of said cylindrical plug portion whereby one or more of said passages are in communication with said auxiliary ports in accordance with the rotative position of said valve member.

Claim 7

The invention set forth in claim 4 wherein: said compressor includes a conduit in communication with said discharge port, a liquid separator and reservoir tank connected to said conduit, and conduit means connected to said reservoir tank and in communication with said passage means for conducting liquid to said passage means for injection into said bores at a flow rate in accordance with the differential pressure between said reservoir tank and said auxiliary port in communication with said passage means.

Claim 8

The invention set forth in claim 4 wherein: said valve member includes a shaft portion and said means for turning said valve member includes a gear connected to said shaft portion, gear means meshed with said gear, and means for reversibly moving said gear means for causing the reversible rotation of said valve member.

Claim 9

The invention set forth in claim 4 together with: means for locking said valve member in a predetermined rotative position, said means comprising a set screw disposed in said casing and engageable with said valve member.

Claim 10

In a helical screw gas compressor: a casing having two parallel intersecting bores; an inlet port and a discharge port opening into said bores; interengaged helical screw rotors disposed in said bores and characterized by cooperating helical grooves and lobes forming working chambers operable to entrap and compress gas admitted to said bores through said inlet port; a cylindrical chamber formed in said casing and having passage means in communication with said inlet port; a plurality of auxiliary ports formed in said casing and opening to at least one of said bores and to said chamber, said auxiliary ports comprising a serIes of oblique slots spaced apart axially with respect to the longitudinal axis of said one bore, the longer sides of said slots forming an angle with respect to said longitudinal axis which corresponds substantially to the helix angle of the rotor disposed in said one bore; a rotatably turnable control valve member comprising a cylindrical plug portion closely fitted in said chamber and forming a closure for said auxiliary ports delimited by a control edge coactable with said auxiliary ports in response to turning of said valve member whereby the gas throughput of said compressor is controlled in accordance with the opening and closing of said auxiliary ports; means for turning said valve member; a longitudinal passage disposed in said valve member and in communication with a source of liquid; and, a series of radially extending passages in said valve member for injecting liquid into said bores for mixing with the gas being compressed by said rotors and for filling up the clearance volume formed between said chamber and said one bore, said passages being spaced apart axially toward said discharge port and with respect to the rotational axis of said valve member and connected to said longitudinal passage, said passages being spaced apart around and opening to the circumference of said cylindrical plug portion, and said passages including respective grooves formed on the circumference of said cylindrical plug portion and proportioned to be cooperable with said auxiliary ports to provide progressively smaller effective flow areas for injection liquid flowing to said bores in accordance with the turning of said valve member to progressively reduce the gas throughput of said compressor, the amount of and axial position of injection of said liquid being in accordance with the rotative position of said valve member.

Claim 11

In a helical screw gas compressor: a casing having two parallel intersecting bores; an inlet port and a discharge port opening into said bores; interengaged helical screw rotors disposed in said bores and characterized by cooperating helical grooves and lobes forming working chambers operable to entrap and compress gas admitted to said bores through said inlet port; a cylindrical chamber formed in said casing and having passage means in communication with said inlet port; a plurality of auxiliary ports formed in said casing and opening to at least one of said bores and to said chamber, said auxiliary ports comprising a serIes of oblique slots spaced apart axially with respect to the longitudinal axis of said one bore, the longer sides of said slots forming an angle with respect to said longitudinal axis which corresponds substantially to the helix angle of the rotor disposed in said one bore; a rotatably turnable control valve member comprising a cylindrical plug portion closely fitted in said chamber and forming a closure for said auxiliary ports delimited by a control edge coactable with said auxiliary ports in response to turning of said valve member whereby the gas throughput of said compressor is controlled in accordance with the opening and closing of said auxiliary ports; means for turning said valve member; a longitudinal passage disposed in said valve member and in communication with a source of liquid; and, a series of radially extending passages in said valve member for injecting liquid into said bores for mixing with the gas being compressed by said rotors and for filling up the clearance volume formed between said chamber and said one bore, said passages being spaced apart axially toward said discharge port and with respect to the rotational axis of said valve member and connected to said longitudinal passage, said passages being spaced apart around and opening to the circumference of said cylindrical plug portion, and said passages including respective grooves formed on the circumference of said cylindrical plug portion and proportioned to be cooperable with said auxiliary ports to provide progressively smaller effective flow areas for injection liquid flowing to said bores in accordance with the turning of said valve member to progressively reduce the gas throughput of said compressor, the amount of and axial position of injection of said liquid being in accordance with the rotative position of said valve member.

Claim 12

In a helical screw gas compressor: a casing having two parallel intersecting bores; an inlet port and a discharge port opening into said bores; interengaged helical screw rotors disposed in said bores and characterized by cooperating helical grooves and lobes forming working chambers operable to entrap and compress gas admitted to said bores through said inlet port; a cylindrical chamber formed in said casing and having passage means in communication with said inlet port; a plurality of auxiliary ports formed in said casing and opening to at least one of said bores and to said chamber, said auxiliary ports comprising a series of oblique slots spaced apart axially with respect to the longitudinal axis of said one bore, the longer sides of said slots forming an angle with respect to said longitudinal axis which corresponds substantially to the helix angle of the rotor disposed in said one bore; a rotatably turnable control valve member comprising a cylindrical plug portion closely fitted in said chamber and forming a closure for said auxiliary ports delimited by a control edge coactable with said auxiliary ports in response to turning of said valve member whereby the gas throughput of said compressor is controlled in accordance with the opening and closing of said auxiliary ports; means for turning said valve member; and, a plurality of passages in said valve member spaced apart axially toward said discharge port and with respect to the rotational axis of said valve member and having progressively smaller effective flow areas toward said discharge port, said passages being spaced apart around and opening to the circumference of said cylindrical plug portion whereby one or more of said passages are in communication with said auxiliary ports in accordance with the rotative position of said valve member for injecting liquid into said bores for mixing with the gas being compressed by said rotors and for filling up the clearance volume formed by said auxiliary ports between said chamber and said one bore, the amount of and axial position of injection of said liquid being in accordance with the rotative positioN of said valve member.

Claim 13

In a helical screw gas compressor: a casing having two parallel intersecting bores; an inlet port and a discharge port opening into said bores; interengaged helical screw rotors disposed in said bores and characterized by cooperating helical grooves and lobes forming working chambers operable to entrap and compress gas admitted to said bores through said inlet port; a cylindrical chamber formed in said casing and having passage means in communication with said inlet port; a plurality of auxiliary ports formed in said casing and opening to at least one of said bores and to said chamber, said auxiliary ports comprising a series of oblique slots spaced apart axially with respect to the longitudinal axis of said one bore, the longer sides of said slots forming an angle with respect to said longitudinal axis which corresponds substantially to the helix angle of the rotor disposed in said one bore; a rotatably turnable control valve member comprising a cylindrical plug portion closely fitted in said chamber and forming a closure for said auxiliary ports delimited by a control edge coactable with said auxiliary ports in response to turning of said valve member whereby the gas throughput of said compressor is controlled in accordance with the opening and closing of said auxiliary ports; means for turning said valve member; and, a plurality of passages in said valve member spaced apart axially toward said discharge port and with respect to the rotational axis of said valve member and having progressively smaller effective flow areas toward said discharge port, said passages being spaced apart around and opening to the circumference of said cylindrical plug portion whereby one or more of said passages are in communication with said auxiliary ports in accordance with the rotative position of said valve member for injecting liquid into said bores for mixing with the gas being compressed by said rotors and for filling up the clearance volume formed by said auxiliary ports between said chamber and said one bore, the amount of and axial position of injection of said liquid being in accordance with the rotative positioN of said valve member.

Claim 14

The invention set forth in claim 10 wherein: said passages are formed as plural pairs of passages, each pair spaced axially closer to said discharge port having a progressively smaller combined effective flow area.