Abstract: The invention relates to a method for the operation of a multi-stage, dry compression vacuum pump (1) with an inlet (7) and an outlet (9), in which the aspirated gases contain gaseous components which endanger the operation of the vacuum pump; in order to render the gas components harmless it is proposed that the gases aspirated from the vacuum chamber (8) and flowing through the vacuum pump be carried through a reaction chamber (14) in which the components endangering the vacuum pump are chemically or physically treated at a pressure between the aspiration pressure and the outlet pressure of the vacuum pump.

Abstract: Lift valves are used for controlling the capacity of a rotary compressor and to vary the built-in volume in the rotary compressor. When controlling the capacity of the rotary compressor, the built-in volume is adjusted by controlling the opening and closing of the lift valves in relation to one another.

Abstract: In a co-rotational scroll apparatus having two interleaving scroll wraps secured to end plates rotating about parallel, non-concentric axes to produce a relative orbital motion, a coupling for causing concurrent rotation and for enhancing the nutational stability of the scroll element. In the preferred embodiment, the nutation reducing means is comprised of an Oldham-type coupling engaging extension members on one of the scroll end plates and drive keys on the other respective end plate. The angular disposition thereof is optimized to cause the Oldham coupling to generate during rotation a moderating moment load in opposition to the tipping moment load of at least one of the scroll elements and thereby enhance the nutational stability of the scroll elements. The moderating moment load of the coupling imposed on the scroll elements may be altered by varying the angular and radial disposition of the center of gravity of the coupling.

Abstract: The invented split gear mechanism replaces a standard single spur gear used within metering pumps and operates in conjunction with a similar driven split gear mechanism. The invention includes two or more layered gear pairs, each layer being re-indexed at a slightly altered fixed orientation relative to a given index point. The invention is typically used within "precision metering pumps" used, for example, in the textile industry. The invention facilitates uniformity by reducing pulsations generated by existing pumps. A method for reducing pulsations in pumping tasks is also included.

Abstract: The axial forces acting upon the orbiting scroll of a scroll compressor during operation produce a resultant force which requires a varying, crank angle dependent radius for dynamic equilibrium. The flat plate or floor portion of the orbiting scroll is provided with a varying radius to provide sufficient radius to be acted on by the resultant force. In a preferred embodiment, the radius is only increased beyond the nominal radius for the angular extent necessary and a diametrically located angular extent of reduced radius is provided to make room for other components and/or to reduce friction.

Abstract: Air and oil from an oil flooded screw compressor is directed through an air-oil separator. The air is cooled to extract moisture therefrom. Then the cooled air is fed to a drying tower and from the tower the air, together with hot oil from the air-oil separator, is fed to a heat exchanger which heats the air to a desired temperature for use and cools the oil to a desired temperature for re-use by the compressor. The regenerating portion of the tower communicates with the outlet of the heat exchanger for supplying dry heated air as purge air for efficient regeneration.

Abstract: A gear pump having improved low-temperature operation includes a housing with a cavity wherein is rotatably received a pair of meshed pinion gears. A pair of bushing members matched in external shape to a projection of the pair of gears and complementary to the housing cavity alone journal the pair of gears. The bushings and gears are freely movable relative to the housing at all operating temperatures for the pump, and the bushings are urged by fluid pressure forces into sealing cooperation with the gears and with the housing. The pump achieves an improved pumping volume by directing a trapped intermesh volume to the outlet port of the pump.

Abstract: Helical screw rotors for a screw rotor machine wherein, for both the male and female rotor, the rotor profile includes involute curves for the male and female rotor lobe tip portion and rotor root portion, thereby generating mating involute curved surfaces of the corresponding groove, root and tip portion for the female rotor, resulting in low leakage path between the high and low pressure volumes when the rotors are in mesh, and causing ramps on the lobe tips of both the male and female rotors to form high points thereof which act as sealing strips during intermesh rotation of the rotors and in conjunction with the screw rotor machine casing.

Abstract: A back pressure chamber seal for use in a scroll type compressor that is located between the adjacent surface on the back of the orbiting scroll and the machine casing. Seals are loosely received in endless grooves formed in one of the two adjacent surfaces and are magnetically held in contact against the other adjacent surface and one wall of the groove to provide a sealed region. A pressurized fluid is delivered into the sealed region to provide an axially disposed biasing force acting against the orbiting scroll.

Abstract: Leakage in a scroll wrap compressor is reduced by providing a roughened scroll wrap tip surface at the gap between the tip and the cooperating base so as to increase the frictional resistance to flow of fluid through the gap and to cause turbulence within the gap to further increase the resistance to the flow of fluid from the high pressure to the low pressure side across a scroll wrap tip. Various types of surfaces are shown for increasing the frictional resistance to flow such as knurling, grooving, cast cavities, metal particles and fibers and the like.

Abstract: A lubricant circuit and a process for circulating a lubricant through such lubricant circuit of a compressor unit incorporating a planetary rotating compressor having a piston in an opening of a cylinder-piston. One embodiment of a circuit and one embodiment of a process of this invention relies on pressure in a lubricant separator vessel to force the flow of lubricant through the circuit to the compressor, and used lubricant pump as a scavenge pump. Another embodiment of a circuit and another embodiment of a process of this invention relies on the pressure developed by the lubricant pump to force the flow of lubricant through the circuit to the compressor, and utilizes a float operated valve to maintain constant lubricant level in the lubricant separator vessel.

Abstract: A rotary compressor and process of compressing compressible fluids wherein the compressor comprises a housing having at least two axially spaced walls and rotatable in relation to the housing cylinder-piston and piston elements journaled on eccentric portions of cylinder-piston and piston shafts rotating in opposite directions. The axially spaced walls of the housing form stationary walls, and the cylinder-piston and piston elements form moveable walls of at least two compression chambers. Circulated compressible fluid is drawn into the compression chambers through intake channel and intake port in the piston shaft and ports in the piston element, and discharged after compression through the same ports in the piston element, and through discharge port and into the discharge channel located in the piston shaft.

Abstract: A hermetic scroll compressor is disclosed including within a hermetically sealed housing a fixed scroll member, an orbiting scroll member, and a crankshaft operably coupled to the orbiting scroll member and driven by a motor. The crankshaft has an axial passageway therein that is in fluid communication with an oil sump located in a discharged pressure chamber within the housing. Upon rotation of the crankshaft, a centrifugal oil pump delivers oil through the axial passageway to the bottom surface of a plate portion of the orbiting scroll member. An oil passage extends through the orbiting scroll plate to introduce oil into a discharge compression chamber established by the intermeshing fixed and orbiting scroll members. Accordingly, oil is introduced into the compression chamber and intermediate the scroll members without the creation of an intentional pressure leak. The size of the oil passage can be varied to affect the amount of oil introduced into the compression chamber.

Abstract: A method of scavenging air and oil from a component (3) of an aircraft for returning the oil to a reservoir (4) for recirculation to the component involves the use of a gear pump (1) for scavenging the oil and gas. The gear pump centrifugally separates oil from the air and returns only the separated oil to the reservoir through outlets located upstream of the mesh zone of the gears while the air is discarded whereby lower discharge pressure of the gear pump is attained and there is no longer a need for a separate air-oil separator.

Abstract: This invention discloses a lubricating mechanism of a hermetically sealed scroll type compressor in which an inner chamber of a housing is kept at suction pressure. The compressor includes a drive shaft supported by bearings in inner blocks. The drive shaft is operatively linked to an orbiting scroll which orbits within a stationary scroll. A rotation prevention device prevents rotation of the orbiting scroll. The drive shaft includes an axial bore extending from an open end and terminating adjacent a forward bearing. A pin extends from the end of the drive shaft to the orbital scroll. A passage links the axial bore to an opening at the end of the pin facing the orbital scroll. Radial bores are provided near the terminal end of the axial bore and at the rearward end of the axial bore near a rearward bearing. The radial bores link the axial bore to a suction chamber of the compressor to allow lubricating oil to lubricate the bearings. The narrow passages allows lubrication of the rotation prevention mechanism.

Abstract: In order to produce oil-free compressed air with a rotary compressor while avoiding the costs involved by a liquid-free compressor, a rotary compressor, especially a single screw rotary compressor is injected with water in which borate, preferably potassium borate is dissolved. This prevents corrosion at no additional cost while improving the bacterial purity of the air produced.

Abstract: A system and method are provided for the automatic regulation of a balancing pressure to be applied to a rotor of a rotary screw compressor. The system includes a microprocessor which computes a balancing pressure to be applied to the rotor in response to an input of various compressor operating parameters such as suction pressure, discharge pressure, and percent capcity.

Abstract: A system is disclosed for preventing oil droplet size reduction when introducing an oil/water stream into an oil-from-water separation unit. The system includes a conduit extending from a source of the oil/water stream to an inlet of the oil-from-water separation unit, which can be one or more hydrocyclone separators, centrifuges, settling tanks and the like. A throttling device is operatively connected to the conduit for regulating the quantity of the oil/water stream passing therethrough. The throttling device eliminates the shearing of the fluid, thereby preventing oil droplet size reduction. The throttling device can include a progressive cavity motor with a rotation control mechanism connected to the rotor of the motor to control the rpm of the rotor, and thus the quantity and pressure of the fluid passing therethrough.

Abstract: A method for producing selectively controlled pressure pulses in a mass of gas, particularly contained in a space of large dimensions. To achieve a sufficiently high power in the pulses, the pulses are generated by a valveless displacement machine in which the pressure when the machine opens towards its outlet port differs from the pressure of the mass of gas. The pulse is generated as the working fluid, due to said pressure difference, flows at high velocity through the outlet port. An acoustic power of the generated pulses of up to 20 kW can be attained by the method. The invention also concerns a rotary displacement machine for performing the method.

Abstract: A screw (1) rotates inside a bore (2a) of a casing and meshes with teeth (6) of a pinion or gate-rotor (7) comprised of a sealing portion (8) supported by a support portion (9). The sealing portion (8) has a limited angular play with respect to the support portion (9). This allows the sealing portion to undergo brief but abrupt accelerations or decelerations independently of the support portion (9). In order to allow frictionless angular displacement between the two portions liquid is injected between them at a moderate pressure when each tooth is out of engagement with the screw.

Abstract: A scroll compressor includes a fixed scroll element stationarily mounted on a support and an orbiting scroll element which is caused by an eccentric crank portion of a drive shaft to conduct an orbiting motion relative to the fixed scroll element. The drive shaft is rotatably mounted on the support by respective support bearings and carries a plurality of counterweights which have such respective masses and angular distributions about the shaft that the loadings of the support bearings by the drive shaft during the operation of the scroll compressor are minimized.

Abstract: A scroll-type hermetic compressor is disclosed including within a hermetically sealed housing a fixed scroll member, an orbiting scroll member, a main bearing frame member, and a crankshaft. An oil sump is located in a discharge pressure chamber in the housing. The frame member and fixed scroll member define a suction pressure chamber in which the orbiting scroll member is disposed. The crankshaft includes a plate portion disposed between the orbiting scroll member and a thrust surface of the frame. Flexible annular seals are disposed within respective interfaces between the orbiting scroll member bottom surface and the plate portion top surface, and between the plate portion bottom surface and the frame thrust surface. The seals provide sealing between a radially inner, oil-filled discharge region and a radially outer suction region, and actuate to compensate for axial space in the interfaces.

Abstract: A scroll compressor can be provided with different wrap thicknesses to compensate for the different material properties of the orbiting and fixed scroll elements. The concept of different wrap thicknesses also aids in the select-fitting of parts and in the provision of and adjustment of a clearance or spacing between the wrap elements. Additionally, in the manufacture of a scroll compressor, the total wrap thickness of the two wraps is kept constant within narrow tolerances while the individual wrap thicknesses are allowed to vary over a predetermined range. The cutting tools used are sized such that even if they differ in their cutting diameters, the combined cutting diameters, and therefore the total wrap thicknesses, are constant within narrow tolerances. This permits the tools to be used and resharpened until their cutting diameters fall below the minimum acceptable diameter.

Abstract: Described herein is a method for operating an oil-free screw compressor and an oil-free screw compressor construction, the method including the step of feeding a gas of a temperature Ta to a discharge space in the vicinity of the discharge port of the compressor, the temperature Ta satisfying the relationshipTa.ltoreq.Tl/kwherein Ta is the temperature (.degree.K.) of said feed gas; Tl is the temperature (.degree.K.) of the compressed gas before feeding; and k is a polytropic index number.

Abstract: A scroll type compressor includes a housing, a pair of scrolls each comprising an end plate and a spiral wrap projecting from one surface of the end plate and a drive shaft supported within the housing. The drive shaft has a crank pin which is inserted into a hole formed in a bushing disposed in a tubular boss on the other end surface of the end plate. The hole in the bushing is formed so as to contact the outer surface of the crank pin at one point along the inner surface of the hole.

Abstract: A vane pump in which an engaging portion in engagement with vanes to restrain the protrusion of the vanes to a given amount is provided on the inner surface of an end wall of a housing, the vanes being made of a material having a relatively high brittleness, the housing having an inner peripheral surface finished into a rough surface so as to restrain the sliding resistance of the vanes resulting from rotation thereof.

Abstract: A scroll compressor is run with a clearance between the wraps and oil is injected between the wraps for sealing. In addition to providing a sealing function, the oil also provides a lubrication function prior to injection.

Abstract: An improved rotory positive displacement blower (10) of the Roots-type with reduced airborne noise and superior efficiency. The blower includes a housing (12) defining generally cylindrical chambers (32, 34) having cylindrical wall surfaces (20a, 20b) and containing meshed lobed rotors (14, 16) having the lobes (14a, 14b, 14c, 16a, 16b, 16c) thereon formed with an end-to-end helical twist according to the relation 360.degree./2n, where n equals the number of lobes per rotor. Preferably, n equals three. The blower housing (12) also defines inlet and outlet ports (36, 38) and the intersections of wall surfaces (20a, 20b) define a cusp (20d) associated with the inlet port (36) and a cusp (20e) associated with outlet port (38). The inlet and outlet port openings are skewed in opposite directions to increase the time the top lands of the lobes are in sealing relation with cylindrical walls (20a, 20b) of chambers ( 32, 34).

Abstract: A scroll compressor has a channel formed in a compressor member such as main shaft, frame, orbital scroll member, through which lubricating oil can pass easily from the higher pressure side to the lower pressure side under flow control between sliding surfaces of the compressor members without reduction in the sealing between the higher pressure side and the lower pressure side, whereby injecting sufficient lubricating oil between the scroll members improves both the sealing and the lubricating between the scroll members.

Abstract: A seal for the drive shaft of a gear pump for polymeric materials dissolved in a fluid solvent is disclosed, and which is adapted to prevent the polymeric material from leaking and hardening on the drive shaft. The seal includes a pair of axially spaced apart annular packing seals surrounding the drive shaft so as to define an annular chamber, and means for supplying a pressurized shielding inert gas, such as nitrogen, into the annular chamber. An outlet line is connected to the lowest portion of the annular space and leads to an air tight container which also contains a shielding inert atmosphere, and such that any polymeric material which leaks along the drive shaft and enters the annular chamber remains in solution, and is withdrawn into the air tight container. A valve is also provided on the container for periodically draining the withdrawn polymeric material therefrom.

Abstract: A first shim mounted on the shaft extending from the high pressure end face of a screw rotor in a screw compressor establishes the operating clearance between the high pressure end face of the rotor and the high pressure end wall of the compressor's working chamber by fixing the axial position of a bearing group which is likewise mounted on the rotor shaft. A second shim, disposed between the bearing group and a spring biased spacer element, is determinative of the distance the spacer element, and therefore the rotor, can travel in a direction toward the high pressure end of the compressor under the impetus of reverse axial thrust. Contact of the rotor with the high pressure end wall of the working chamber is positively precluded because movement of the spacer element, under the influence of rotor movement toward the high pressure end of the compressor, collapses the biasing spring which causes the spacer element to contact a fixed surface of the compressor.

Abstract: A rotary device and method for replacing apex seals is provided. The rotary device comprises a housing having a peripheral wall surface and two inner side walls that define a chamber. A rotor is located within the chamber and rotates therein. The peripheral wall surface of the housing includes a plurality of slots having disposed therein an insert, a wave spring, and an apex seal. The apex seal extends radially outward from the slot and is spring biased by the wave spring that is sandwiched between the insert and apex seal. The side walls of the housing include spring biased button seals. The button seals are urged against a portion of the apex seal. A side wall of the housing includes a rotatable nut for relieving the spring pressure on the button seal and an aperture covered by a removable cap for accessing the insert member so that it can be removed. A method of replacing the apex seals is also provided.

Abstract: Variations in pump capacity of gear pumps due to varying leakage paths occurring in otherwise identical pumps as a result of the manufacturing operation are minimized without unduly hindering the fitting of the bearings through the pump housing by maintaining the distance "TBD" between the center of the bearing journal and the bearing flat closely within tolerances and by providing a relief in the bearing periphery diametrically opposite of the flat.

Abstract: A thrust reducing apparatus for a progressing cavity pump used in a well and driven by a submersible pump motor. A piston is mounted to the top of the rotor and located in a bore between the stator and the tubing which extends to the surface. A bypass passage enables fluid discharged from the pump to flow past the bore and the piston. An annulus passage extends into the bore above the piston for communicating fluid pressure in the annulus to the top of the piston. The lower side of the piston is exposed to discharge fluid pressure from the pump, resulting in a net upward force on the piston. The piston pulls upwardly on the rotor to reduce the downward thrust on the rotor.

Abstract: A rotary hermetic compressor including a compressor cylinder having a bore therein, and a sliding vane slidably disposed in a slot in the compressor wall. The vane extends into the bore of the cylinder for cooperating with a roller to divide the compression chamber into a suction chamber and a discharge chamber. A pressure groove is formed in the wall of the slot on the suction side of the vane. The pressure groove is supplied with oil by means of a passage directly connecting the groove with the oil sump whereby a bias force is applied to the vane to partially offset the unbalanced lateral force on the vane portion extending into the cylinder bore.

Abstract: The reversing of the direction of rotation of the motor of a fixed vane rotary compressor reverses the direction of rotation of the rolling piston. The rolling piston through viscous friction or frictional torque frictionally engages a reversing disk and causes the reversing disk to move between two positions depending upon the direction of rotation of the rolling piston. The reversing disk has a slot therein which forms the suction inlet and is moved by rotation of the reversing disk so as to be in fluid communication with the plenum which is serving as the suction plenum at that time.

Abstract: A hydraulic torque motor and more particularly a hydraulic torque motor 10 of the internally generated rotor family having a rotatable inner rotor 24 and an orbital outer rotor 26 and which includes an improved rotary valve means 66 for the delivery and exhaust of hydraulic pressure fluid thereto and therefrom.

Abstract: The invention relates to a positive displacement machine, such as a rotary pump, engine or compressor. This machine has a slotted rotor, sealing elements sliding in the slots and a tubular stator formed with a cylindrical inner surface, the contour line of which is particular. This contour line has a symmetry order s.sub.S and is composed of s.sub.S lobes belonging to a shortened hypertrochoid with a core, the symmetry order of this hypertrochoid being s.sub.H .noteq.s.sub.S, and s.sub.S sealing zones belonging to the contour line of the core of the hypertrochoid. Each lobe has a center point angle .theta..sub.H, each sealing zone a center point angle .theta..sub.c, .theta..sub.H and S.sub.H being related to .theta..sub.c and s.sub.S by the expressions:.theta..sub.H =(2.pi./s.sub.S -.theta..sub.cands.sub.H /s.sub.S =(.theta..sub.H +.theta..sub.c)/.theta..sub.H.

Abstract: A method of cooling the oil in screw compressors equipped with automatic variable volume ratio by automatically relocating the proper ports for the injection of liquid refrigerant into the interlobe volume of the compressor in response to the instantaneous internal volume ratio so that the refrigerant injection is done at an optimum time to insure efficient use of the refrigerant.

Abstract: A seal for the drive shaft of a gear pump for melted polymeric materials is provided, which includes a reduced pressure zone, a mechanical packing seal, and a liquid filled chamber positioned in succession along the drive shaft. The liquid is a solvent for the polymeric material, and it is maintained under a pressure slightly above that in the reduced pressure zone. Thus a small quantity of the liquid tends to move axially into the reduced pressure zone where it dissolves any polymeric material leaking thereinto. A failure of the seal may be readily detected by monitoring the volume of the liquid, since any polymeric material leaking axially through the packing seal will be dissolved by the liquid in the chamber, thereby increasing the volume of the liquid.

Abstract: A backup fuel pump (16) has a thermal fuse (40) positioned in a bearing. The fuse is adapted to melt at a predetermined temperature during dry running of the pump. Melting of the fuse causes a spring urged braking member (42) to screw into a shaft journal (26) and terminate operation of the pump.

Abstract: A gear pump structure is provided having a housing with a pump chamber, a suction chamber and a discharge chamber communicating with said pump chamber on opposite sides thereof, a suction port and a discharge port in said housing communicating respectively with the suction chamber and discharge chamber, each of said ports have spaced apart inlet and outlet means, said suction port being contoured to provide on introduction of fluid into the inlet end a point intermediate its inlet and outlet means having a pressure higher than the pressure at the inlet and outlet means, at least one pair of meshing gears mounted for rotation in said pump chamber and each having two axially spaced trunnions, a plurality of bearing means in said housing each having an axial bore mounting said trunnions for rotation in the pump chamber, drive means for rotating said gears so that liquid which is drawn through the suction port into the suction chamber is engaged by teeth on said gears and transferred to the discharge port under p

Abstract: This invention relates to a method at oil-injected screw-compressors for balancing axial forces at at least one of the rotors of the compressor, for sealing the gaps between rotor housing and rotor shafts and for cooling and lubricating the bearings of the rotor shafts. At the high-pressure end of the compressor oil under pressure of such magnitude is supplied to the bearing spaces (28a,28b) at the ends of both rotors that an oil flow inward to the compression space along the gaps (32a, 32b) between the rotor shafts and the rotor housing is obtained for sealing against leakage from the compression space. Oil at this pressure further is supplied via a connection (42) from the bearing space (28b) of the female rotor to a pressure space (38) at the low-pressure end of the female rotor for balancing the axial force arising on the shaft end (31) of the female rotor on the high-pressure side due to the oil supplied to the bearing space (28b) of the female rotor.

Abstract: This invention relates to a method and a device for intermediate cooling in an oil-injected multi-stage screw compressor. Between the outlet (14) in one stage (10) and the inlet (16) in a subsequent stage (11) a connecting passageway (15) is located, through which the gas compressed in the firstmentioned stage (10) is supplied to the subsequent stage (11). For cooling the gas flowing out from the firstmentioned stage (10), in the connecting passageway (15) at least one nozzle (19) is located for the supply of a large cooling oil amount.

Abstract: A hermetic refrigeration rotary motor-compressor comprising a hermetically sealed pressure tight housing can enclosing a compressor unit comprising rotary cylinder-piston and piston elements journaled on eccentrics of two oppositely rotatable shafts, and a motor unit for driving the compressor unit having a rotor mounted on one of the compressor unit shafts, with a stator of the motor unit positioned in operative relation to the rotor of the motor unit. The piston and cylinder-piston form moveable walls, and two axially spaced walls form stationary walls of a compression chamber. An intake charge of refrigerant vapor may cool the motor unit and is admitted into the compression chamber through intake ports and discharged through a system of discharge valves into the discharge line.

Abstract: A hermetic refrigeration rotary motor-compressor comprising a hermetically sealed pressure tight housing can enclosing a compressor unit comprising a housing having at least two axially spaced walls and rotatable in relation to the housing piston and cylinder-piston journaled on eccentric portions of two oppositely rotatable shafts. The piston and cylinder-piston form movable walls, and axially spaced walls of the housing form stationary walls of at least two compression chambers. The compressor unit may be operated by any suitable prime mover, preferably an electric motor. An intake charge of refrigerant vapor may cool the motor unit and is admitted into the compression chamber through intake ports and discharged through a system of discharge valves into the discharge line.

Abstract: In order to prevent a decrease in volumetric efficiency from occurring when a gear pump or motor, 10, is operated at room temperature after operating at a lower temperature or when it is operated at a higher temperature after operation at a lower temperature, the housing, 13, containing two interlocking gears 17 and 18 is made of a ferrous material, which is the same as that of the two gears, and a large number of serrated grooves, 40, are disposed in the axial direction on the low pressure side of the inner wall surfaces of the gear bower 16.

Abstract: A rotary air compressor includes a rotor which rotates within a housing and controls communication through inlet and outlet ports provided on the housing and compresses air communicated through the inlet port for delivery to the outlet port. The inlet and outlet ports are provided with check valves controlling communication therethrough. After the rotor rotates through a dead-center position, the check valves in both the inlet and outlet ports are closed. The rotor then rotates into a position in which the apex seals carried by the rotor wipe across the inlet and outlet ports simultaneously, thereby opening a communication path bypassing the apex seals so that the pressure levels in the chambers across the rotor are equalized. As the rotor continues to rotate, air is compressed and communicated to the outlet port.

Abstract: A method for preventing a leakage loss of gases in an oil-free screw type rotary compressor including a housing, a rotor assembly comprising a pair of male and female rotor members rotatably mounted within said housing and a cooling jacket surrounding said housing, said housing and said pair of male and female rotor members defining therebetween an axially progressive series of sealed cavities for a gas, which method comprises the steps of returning as cooled a leakage gas from rotor shaft seals on the discharge side of said compressor to a first of said axially progressive series of sealed cavities, the leakage gas being returned to the compressor at a point where the suction cycle has been completed and the compression cycle has yet to begin.

Abstract: This invention relates to a method at oil-injected screw-compressors for balancing axial forces at at least one of the rotors of the compressor, for sealing the gaps between rotor housing and rotor shafts and for cooling and lubricating the bearings of the rotor shafts. At the high-pressure end of the compressor oil under pressure of such magnitude is supplied to the bearing spaces (28a,28b) at the ends of both rotors that an oil flow inward to the compression space along the gaps (32a,32b) between the rotor shafts and the rotor housing is obtained for sealing against leakage from the compression space. Oil at this pressure further is supplied via a connection (42) from the bearing space (28b) of the female rotor to a pressure space (38) at the low-pressure end of the female rotor for balancing the axial force arising on the shaft end (31) of the female rotor on the high-pressure side due to the oil supplied to the bearing space (28b) of the female rotor.