Abstract: The invention is relative to a series of gear motors for differing output volumes with at least two gear motors. Each gear motor has at least two intermeshing displacing elements, a first displacing element and a second displacing element in the form of gears. The individual gear motors of the series comprise substantially identical dimensions for the axial interval between the theoretical axes and between the theoretical axes of rotation of the two displacing elements, and a substantially identical gearing width in the form of a substantially identical axial extension of the gearing elements. The individual gear motors differ from each other at least as regards the size of the tip circle diameter of at least one of the two displacing elements.

Abstract: A cooled screw vacuum pump has a housing (4) two rotating systems (5, 6) consisting each of a screw rotor (5) and a shaft (6), a floating device supporting the rotors having, on each shaft, two mutually spaced bearings (7, 8) and an empty space (31) arranged in each rotor (5) open on the bearing side, wherein is respectively located an element cooling the rotor internally. In order to improve cooling it is suggested that the bearing (7) of the support located on the rotor side, is placed outside the rotor (5) empty space (31), such that in said empty space (31) there is more room available for obtaining efficient cooling.

Abstract: The invention is related to a series gear pump for differing output volumes with at least two gear pumps, each gear pump comprises at least two intermeshing displacing elements, a first displacing element and a second displacing element in the form of gears. The individual gear pumps of the series comprise a substantially identical dimensions for the axial interval between the theoretical axes and between the theoretical axes of rotation of the two displacing elements, and a substantially identical gearing width in the form of a substantially identical axial extension of the gearing elements. The individual gear pumps differ from each other at least as regards the size of the tip circle diameter of at least one of the two displacing elements.

Abstract: In an oil-free type screw compressor including a low-pressure-stage compressor main body and a high-pressure-stage compressor main body, when the power of an motor is transmitted to an oil pump via a gear to start the pump, the lubrication oil stored in an oil sump formed at the bottom of a gear casing flows through an oil strainer. A part of the oil is introduced to an oil cooler, while the rest is introduced to a junction portion by bypassing the oil cooler. Further, a part of the oil introduced to the oil cooler is directed to the junction portion. After adjusting the temperature of the oil appropriately, it is introduced to a lubrication portion of the compressor, while the oil cooled by the oil cooler using the full capacity thereof is introduced to oil jackets of the compressor main bodies via different passages.

Abstract: A combination double screw rotor assembly includes a first and a second screw rotor arranged in parallel in a casing, two sets of bearings respectively mounted in the casing near the outlet to support the shafts, and a plurality of locking means respectively fastened to the shafts near the inlet. The first and the second screw rotor each has a low pressure screw rotor element, a high pressure screw rotor element, and a spiral thread formed of a first spiral thread segment at the high pressure screw rotor element and a second spiral thread segment at the low pressure screw rotor element, the first spiral thread segment having an uniform short pitch, the second spiral thread segment having an uniform long pitch, the first spiral thread segment and second spiral thread segment of the first and the second screw rotor being respectively meshed together.

Abstract: Fixed throttle devices 36A, 36B, 36C, 36D are screw-engaged with a rotor housing 12. A fixed throttle device 37is screw-engaged with a front housing 13, and a fixed throttle device 38is screw-engaged with a rear housing 14. Inert gas is supplied to the respective throttle devices 36A, 36B, 36C, 36D, 37and 38via branch pipes 54 to 59. Each of the throttle devices 36A, 36B, 36C, 36D, 37and 38includes a check valve 44, a fixed throttle 45 screw-engaged with the check valve 44, and a pipe joint 46 screw-engaged with the check valve 44.

Abstract: The invention concerns a vacuum pump consisting in the assembly of two stator half-shells (101, 102) and two directly mounted end parts (31, 32) with an interposed single-piece continuous pressure seal (33). The pressure seal (33) comprises two annular end parts (34, 35) generally parallel to each other and connected by two side-members (36, 37) which are generally perpendicular thereto. Thus, the number of components to be assembled to produce an multistage dry vacuum pump is reduced, while providing satisfactory impermeability to outside atmosphere.

Abstract: Displacement machines for compressible media having single-threaded, twin screw rotors with continuously decreasing pitch to achieve an inner compression are known. The demand for compact pumps with rotors as short as possible, and the frequent, process-related demand for quick disassembly of the housing, set limits however for the wrapping angle or respectively for the variation of the end profiles, which, in turn, leads to extreme pitch ratios or to insufficient compression rates. The present invention uses screw rotors with an optimized, non-monotone pitch course and alternative end profile variation with constant diameters. Suction capability is improved with the same space requirement, and compression rates of 3.0 and more are achieved easily with only four wraps. Displacement machines equipped with such twin screw rotors provide optimal results with respect to energy requirement, temperature, construction space and servicing with application possibilities in chemistry and in semiconductor technology.

Abstract: A displacement machine for compressible media has at least two shafts with rotors which are designed as helical profile bodies. During rotation, the profiles intermesh like gears and run free of contact relative to one another. The lead of the helical profile bodies decreases from the inlet end to the outlet end and have a double-start design, with the leads at the inlet end and outlet end of the helical profile bodies being constant, and the intermediate lead decreasing continuously from the larger lead at the inlet end to the smaller lead at the outlet end.

Abstract: A combination double screw rotor assembly includes a first screw rotor and a second screw rotor arranged in parallel in a casing, the first screw rotor and the second screw rotor each having a low pressure screw rotor element, a high pressure screw rotor element, and a spiral thread formed of a first spiral thread segment at the high pressure screw rotor element and a second spiral thread segment at the low pressure screw rotor element, the first spiral thread segment having an uniform short pitch, the second spiral thread segment having an uniform long pitch, the upper spiral thread segment and second spiral thread segment of the first screw rotor being respectively meshed with the first spiral thread segment and second spiral thread segment of the second screw rotor.

Abstract: Fixed throttle devices 36A, 36B, 36C, 36D are screw-engaged with a rotor housing 12. A fixed throttle device 37 is screw-engaged with a front housing 13, and a fixed throttle device 38 is screw-engaged with a rear housing 14. Inert gas is supplied to the respective throttle devices 36A, 36B, 36C, 36D, 37 and 38 via branch pipes 54 to 59. Each of the throttle devices 36A, 36B, 36C, 36D, 37 and 38 includes a check valve 44, a fixed throttle 45 screw-engaged with the check valve 44, and a pipe joint 46 screw-engaged with the check valve 44.

Abstract: A package-type screw compressor includes a low-pressure stage state compressor and a high-pressure stage compressor. Motive power is transmitted from an electric motor to the two compressors via a speed increaser. The discharge gas, compressed and heated to a high temperature by the low-pressure stage compressor, is cooled by an intercooler. The discharge gas, compressed and heated to a high temperature by the high-pressure stage compressor, is cooled by an aftercooler. A casing of the intercooler and that of the aftercooler are formed integrally with a speed increaser casing, reducing the number of component parts. A cooler portion, formed by the intercooler and the aftercooler, is spaced from the speed increaser casing, thereby preventing heat, produced by the compressed air, from being transmitted to the speed increaser casing.

Abstract: Device intended for two-phase compression of several fluids such as a gas soluble in an essentially liquid solvent.

Abstract: A multistage vacuum pump assembly comprising plural independent pumping stages connected in series is disclosed. A first pumping stage located at one end of the series is connected to a room to be evacuated, and a final pumping stage located at the other end of the series is connected to the atmosphere. At least the first pumping stage comprises plural pumps connected mutually in parallel, so that the plural pumps together can achieve the vacuum capacity expected without being driven to an excessive rate of rotation.

Abstract: A trochoidal gear pump or engine uses a coaxial hub with the outer and/or inner rotor and an associated rolling element bearing assembly that preferably uses pre-loaded bearings to precisely set the rotational axis and/or the axial position of the rotor with which it is associated. This allows the fixed-gap clearance between the rotor surfaces and the housing surfaces or the other rotor surfaces to be set at a distance that minimizes operating fluid shear forces and/or by-pass leakage and eliminates gear tooth wear thus preserving effective chamber to chamber sealing. The device is useful in handling gaseous and two-phase fluids in expansion/contracting fluid engines/compressors and can incorporate an output shaft that accommodates an integrated condensate pump for use with Rankine cycles. A vent from the housing cavity to a lower pressure input or output port regulates built-up fluid pressure in the housing thereby optimizing the efficiency of the device by controlling bypass leakage.

Abstract: A compound vacuum pump incorporating a screw mechanism section. The screw mechanism section comprising two externally threaded rotors mounted on respective shafts in a pump body. The rotors are adapted for counter-rotation in a first chamber within the pump body with intermeshing of the rotor threads to pump gas by action of the rotors. The root diameter of each rotor increases and the thread diameter of each rotor decreases in a direction taken from pump inlet and in which the gas is pumped. The pump additionally incorporates a roots mechanism section comprising two roots-type profile rotors also mounted on the respective shafts and adapted for counter-rotation in a second chamber within the pump body situated at an inlet end of the pump.

Abstract: A multistage pump includes a shaft assembly and a housing and spacing plates. The shaft assembly completed by forming shafts and rotors integrally. The spacing plates defining a plurality of successive compression chambers, each chamber is delimited by two symmetrical spacing plates, there has a ring groove associated with the spacing plates, and having an elastic component placed. When the elastic component pressed by the housing, it became leakage and the clearance between the rotors and the spacing plates be easily controlled, by this way, the pump using parts are easy to manufacture, can be machined accurately and which enable highly accurate assembly to be achieved. As to the assembling method, which is characterized by mounting the high pressure end axial bearing seat and the high pressured end plate, then to control the clearance between the high pressure end plate of the bearing seat and the rotors. Furthermore, to install the spacing plates and the housing make the compression chamber formed.

Abstract: An evacuating apparatus includes a first pump section disposed on a suction opening side, a second pump section for exhausting a smaller amount of gas than the first pump section, the second pump being disposed in an exhaust opening side, a plurality of rotors accommodated in a housing, bearings for supporting rotation of the rotors, a suction opening for drawing fluid and a first exhaust opening thereof both formed on the housing, and a plurality of motors for driving the rotors. In the apparatus, the first pump section is a pump of positive displacement type formed by utilizing a volume change of a space defined by the rotors and the housing, and the second pump section is a viscous-type pump formed by utilizing a relatively moving surface formed in a small gap defined between the rotors and the housing.

Abstract: Apparatuses are described for cooling the rotors of, improving the sealing of, and improving the power efficiency of twin-screw pumps. Such methods include (1) injecting liquid onto the rotor and into the rotor chambers at the point of greatest temperature accumulation, (2) implanting a heat transfer device within the rotor enclosure that can transfer heat outside of the rotor enclosure, and (3) injecting liquid into rotor chambers via energy recovery devices which reduce the total power consumption of the system.

Abstract: A rotary screw compressor having one or more stages (10, 20) is provided with a lift valve (14, 24) on each stage for unloading the compressor at starting up and rest periods. Each lift valve (14, 24) is biased by a spring (15, 25) towards an open position and can be closed by an actuator (17, 27). Each valve actuator (17, 27) is automatically controlled by an air conduit (32) establishing air communication between the discharge channel (23) of the compressor and each valve actuator (17, 27).

Abstract: A mechanical vacuum pump having mounted in each of at least three pumping chambers a pair of intermeshing rotors. A first rotor of each pair being mounted for rotation on a first shaft passing through the chambers and a second rotor of each pair being mounted for rotation on a second shaft passing through the chambers. The first and second shafts are driven in contra-rotating directions to effect a sequential pumping action by the pairs of rotors in each chamber in respect of gas being pumped between a pump inlet and a pump outlet. The pump possesses at least one chamber with claw-type profile rotors and one ore more chambers with roots-type profile rotors. The chamber nearest the pump outlet has a rotor with a roots-type profile.

Abstract: A screw type dry vacuum pump having dual shafts is disclosed, whereby the process gas is transported through three compartments, a gas admittance pump section, a central drive motor section, and a gas discharge pump section. By placing the drive motor in the center of the pump, it becomes possible to design a pump having the dual shafts supported only at one end, thus enabling to mount the rotors at the free ends of the pump which are closed with end plates which can be removed easily for servicing the pump sections. Synchronous operation of the dual shaft pump by magnetic coupling enables to lower power consumption and to extend the range of operable pressures.

Abstract: At least two progressing cavity pumps or pump sections are connected in series. The flow volume rate of the second pump or pump section is less than the flow volume rate of the first pump or pump section. If there are more than two pumps or pumps sections, the flow volume rate of the third pump or pump section would be less than the flow volume rate of the second pump or pump section, and so on. The cascade arrangement of progressing cavity pumps can be achieved by interconnecting separate pump assemblies end to end. The cascade arrangement of progressing cavity pump sections can be achieved by the attachment of the rotor/stator pairs of each pump section in series with suitable universal mechanisms and housings. Such a cascade arrangement of progressing cavity pumps or pump sections allows and compensates for the compressibility of the gas in the two-phase or multi-phase fluid being pumped, especially in pumping operations requiring high differential pressures.

Abstract: A multistage positive-displacement vacuum pump which is preferably used in the fabrication of semiconductor devices and can be operated from atmospheric pressure. The vacuum pump comprises a pump casing, a pump assembly housed in the pump casing and comprising a pair of pump rotors rotatable in synchronism with each other and arranged in multiple stages, and an intermediate pressure chamber provided between a preceding stage and a subsequent stage in the pump casing. The shaft portions of the pump rotors located between the preceding and subsequent stages are located in the intermediate pressure chamber.

Abstract: A gear-type pump having an inner rotor and an outer rotor and in which the outer rotor is supported for rotation by a plurality of roller bearings interposed between a support housing and the outer rotor and in which the inner and outer rotors and the support housing are made of the same material and have essentially the same width dimension so that the thermal contraction of the support housing and the thermal contraction of the inner and outer rotors while pumping super-cooled fluid does not adversely affect the end-clearance between the end plates and the inner and outer rotors to an extent where the efficiency of the pump would differ if it were pumping fluid at a temperature of 70 degrees Fahrenheit.

Abstract: There is disclosed an apparatus for pumping multiphase fluids in oil field production, particularly a twin-screw pump for providing a large pressure boost to high gas-fraction inlet streams. The pump includes a housing having an internal rotor enclosure, the enclosure having an inlet and an outlet and a plurality of rotors operably contained in the enclosure. Each rotor has a shaft and a plurality of outwardly extending threads affixed thereon, the rotors being shaped to provide a non-uniform volumetric delivery rate along the length of each rotor. The pump also has means for rotating the rotors, whereby a fluid stream entering from the inlet is subjected to a pumping action to transport the fluid stream to exit the rotor enclosure through the outlet. In one embodiment, the rotors have a plurality of threaded pumping stages separated by unthreaded non-pumping chambers.

Abstract: An evacuating apparatus includes a first pump section disposed on a suction opening side, a second pump section for exhausting a smaller amount of gas than the first pump section, the second pump being disposed in an exhaust opening side, a plurality of rotors accommodated in a housing, bearings for supporting rotation of the rotors, a suction opening for drawing fluid and a first exhaust opening thereof both formed on the housing, and a plurality of motors for driving the rotors. In the apparatus, the first pump section is a pump of positive displacement type formed by utilizing a volume change of a space defined by the rotors and the housing, and the second pump section is a viscous-type pump formed by utilizing a relatively moving surface formed in a small gap defined between the rotors and the housing.

Abstract: A rotary positive displacement blower for producing a flow of fluid. The blower includes a housing having a rotor chamber, an inlet port and an outlet port. The outlet port has a first end and a second end and a first edge and a second edge which extend from the first end towards the second end while becoming increasingly spaced apart from one another. A first rotor and a second rotor are located in the rotor chamber. Each rotor includes a plurality of lobes and are each rotatable about a respective axis. Each rotor includes a plurality of pockets adapted to rotate into fluid communication with the inlet port to receive fluid and to rotate into fluid communication with the outlet port to deliver fluid as the rotors rotate.

Abstract: In a screw fluid machine including male and female rotors which are engaged with each other, a casing for accommodating both the male and female rotors, fluid working rooms which are formed by the male and female rotors and the casing, and fluid inlet and outlet ports which are provided in the casing so as to intercommunicate with one end portion and the other end portion of the working rooms, the helix angle of the screw gear constituting each of the male and female rotors is set to be continuously varied in a helix advance direction. Further, the screw gear is designed so that the peripheral length of a pitch cylinder in a helix advance direction on a development of a tooth-trace rolling curve on the pitch cylinder of the screw gear can be expressed by a substantially monotonically increasing function.

Abstract: A screw displacement pump has a chamber. Inlet and outlet are provided for the admission of gas to and discharge of gas from the chamber. Intermeshing screw members rotatably mounted within the chamber for delivering the gas from the inlet to outlet, wherein the pitch of the screw members decrease continuoulsy from the inlet end thereof to the outlet end thereof to cause compression of the gas being delivered. The continuous reduction in the pitch distance from the inlet end to the outlet end is generated by the following relationship:Pitch at the outlet end/Pitch at the inlet end<.pi..sub.i /kwhere, .pi..sub.i =pressure ratio calculated under the condition that the process is effected in a adiabatic and the work done is constant, C.sub.1 =0, and k is gas constant.

Abstract: A method of operating a claw-type vacuum pump with two or more stages, each of which has a suction chamber with a pair of claw rotors and end-located suction and discharge ports. To avoid the possibility of liquids affecting operation of the pump, the invention proposes that the pump is operated without internal compression and that the gases emerging from at least one stage are cooled.

Abstract: A composite dry vacuum pump of this invention has closed chambers accommodating a pair of screw rotors and a pair of roots rotors respectively mounted coaxially to the front ends of the screw rotors. The roots rotors and the screw rotors are rotated at the same speed in opposite directions by a motor to aspirate fluids from a suction port on one end wall and discharge the fluid through a discharge port on the outer surface of the other end wall. The characteristics of power requirement of the portion of the roots rotors and that of the portion of the screw rotors changes inversely to the suction port pressure variation, therefore the characteristic of the total power requirement of the pump of this invention is almost flat over the all pressure range and the motor having smaller output power can operate the pump according to the present invention.

Abstract: A vacuum pump includes a plurality of rotors accommodated in a housing, a plurality of bearings for supporting the shafts of the rotors, respectively, a fluid-suction opening and a fluid-discharge opening formed in the housing, and a motor for driving at least one of the rotors. The pump has a first pump structure section for suction and discharge of gas, the pressure of which is in a viscous flow region, by utilizing change in volume of a space formed by the rotors and the housing. A second pump structure section is provided for transporting gas, a pressure of which is in an intermediate flow region, and gas, the pressure of which is lower than a pressure of the intermediate flow region, by utilizing movement of the space from a suction side to a discharge side of the second pump structure section.

Abstract: A mechanical vacuum pump is provided with a pair of cooperating rotors mounted on rotatable shafts within a pumping chamber. Each of the pair of cooperating rotors has a claw profile that terminates in a leading edge shaped to present an angle of no greater than 90 degrees relative to the wall of the pumping chamber. The leading edge shaped in such manner helps to prevent contaminant buildup on the wall of the pumping chamber.

Abstract: A multi-stage screw vacuum pump having a reduced number of constituent parts as compared with the conventional one and a reduced overall size. The multi-stage screw vacuum pump comprises an input mechanism for transmitting a driving force derived from a driving source to a former-stage pump, and speed up mechanisms for speeding up the rotation of the former-stage pump for transmission to a latter-stage pump.

Abstract: To provide a screw vacuum pump which is compact and yet capable of attaining a high degree of vacuum. A screw vacuum pump having a pair of male and female rotors 7 and 7A rotating in mesh with each other around two parallel axes, respectively, and a casing 1 for accommodating the two rotors 7 and 7A, the casing 1 having a suction port 8b and a discharge port 9b, the screw vacuum pump further having a process of sucking a gas from the suction port 8b into a space defined between the rotors 7 and 7A, a process of transferring the gas, a process of compressing the gas, and a process of discharging the gas from the discharge port 9b, wherein the suction port 8b is closed early, thereby providing an expansion process between the suction and transfer processes.

Abstract: Dry-running twin-shaft vacuum pump (1) with at least one pumping chamber (11, 12, 13), with a rotor pair (4-5, 6-7, 8-9) situated in the pumping chamber and borne by the shafts, and with a drive housing (21); in the pumping of toxic media, to limit the contaminated areas to components that are easy to assemble it is proposed that between the drive housing (21) and the adjoining pumping chamber (13) an intermediate plate be provided, which is traversed by the shafts (2, 3), contains the laterally exiting exhaust duct (52), and is releasable from the wall (17) of the drive housing (21).

Abstract: The invention relates to a system for supplying inert gas to a multi-stage, dry-running vacuum pump (1) with systems for distributing the inert gas to the pump stages. To be able to monitor the flow of the inert gas and/or influence the rate of flow, a modularly constructed apparatus (36) with inert gas inlet, inert gas outlets and inert gas conduits is proposed, which is equipped with monitoring components.

Abstract: A screw vacuum pump is designed so that it is possible to reduce the load on the pump at the time of starting and evacuation of a gas under atmospheric pressure. The screw vacuum pump has male and female rotors rotating in mesh with each other around two parallel axes, respectively, and a casing for accommodating the rotors, the casing having a suction port and a discharge port, wherein the discharge port is formed so that V.sub.1 /V.sub.2 is in the range of 1.5 to 0.51, where V.sub.1 is a groove volume defined by the casing and the male and female rotors immediately after a gas has been trapped, and V.sub.2 is a groove volume immediately before the gas is discharged.

Abstract: The invention relates to a rotary screw machine in which the shaft journals (20, 22) of the rotors (10) are journalled in a main thrust bearing (24) and a thrust balancing bearing (26). The thrust balancing bearing (26) is preloaded by springs (36) and by fluid pressure means (40, 44). According to the invention the fluid pressure means (40, 44) can excert a force on the thrust balancing bearing (26) in either axial direction. This increases the possibility for an optimal distribution of the forces on the thrust bearings (24, 26) at various running conditions.

Abstract: An air-cooled oil-free screw compressor is provided with a first lubricating oil circulating flowpassage 1 which extends from an oil tank 20 via an oil pump 21 and an air heat exchanger 22 to cooling jackets 15 and 16 for cooling compressor bodies 12 and 13. A second such passage is connected between the cooling jackets and the oil tank and includes an oil filter 23, lubricating oil.

Abstract: A screw vacuum pump is capable of reducing the load thereon at the time of evacuation of a gas at atmospheric pressure by the use of a throttle plate. The screw vacuum pump has male and female rotors which rotate in meshing engagement with each other around two parallel axes, respectively, in a casing so that a gas that is sucked in from a suction opening is introduced through a suction port into a groove space defined between the male and female rotors and the casing is then discharged from a discharge opening through a discharge port, wherein the throttle plate is provided upstream of and near the opening of the suction port.

Abstract: An improvement is provided in a gear pump comprising a pair of intermeshing gears enclosed in a housing, the improvement comprising having at least one additional pair of intermeshing gears, wherein the gear pairs are non-meshing with one another.

Abstract: A multistage vacuum pump including a plural set of two lobe type vacuum pumps arranged on a common shaft for rotors and in a common casing. The adjacent pumps are connected in series with each other through a communicating passage formed in a pump casing. A solid material collector having a cooling device is provided in the communicating passage so that it is dismountable from the pump casing. A solid component in a compressed gas is forcibly produced by and adhered to the solid material collector. Thus, it is not necessary to disassemble the pump casing for cleaning the same.

Abstract: A liquid nozzle in use with an interstage passage of a two stage compressor and includes a first elongated element having a first elongated surface and a second elongated element having a second elongated surface. The first and second elongated surfaces are configured for mating engagement. A channel is formed in at least one of said first or second elongated surfaces with a coolant liquid in communication therewith. A first slot is formed in said first elongated surface. The first slot and the second elongated surface define a liquid orifice communicating the channel with said interstage passage. The nozzle preferably extends across an entire width of the interstage passage.

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: A rotary piston engine comprising two segregated body chambers of compression and expansion, and one separable combustion chamber, carrying out air suction and compression, combustion resultant expansion and exhaust, and fuel injection and constant-volume combustion process without any valve respectively: the compression and the expansion chamber both are arranged parallel adjacent to each other, both are formed by two partially overlapped body-bores provided respectively with cylindrical hubs at respective centers thereof, both have a pair of screwed rotors rotatably mounted on said respective hubs, and both communicate to each other by the combustion chamber and gas passageway means; it is characteristic in configuration that the closed space made by rotor projecting portions are progressively changed in geometry as rotors rotate, and that exhaust gases make no explosion noises.

Abstract: A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.

Abstract: The invention is directed to a method for the operation of a twin shaft vacuum pump (1) having two rotors (4, 5; 6, 7; 8, 9) that rotate synchronously and in non-contacting fashion in a pump chamber, each being provided with a respective projection (38) and a recess (39), the one of said rotors controlling an admission opening (32, 35) and the other controlling a discharge opening (33, 37, 42); the invention is also directed to a twin shaft vacuum pump suitable for the implementation of the method; in order to be able to admit flushing gas into a twin shaft vacuum of this species during operation as well, it is proposed that flushing gas be admitted into the respectively diminishing pump volume via an orifice (45) that is controlled such by the rotor at the discharge side that the respective pump volume is closed both toward the admission opening (35) as well as toward the discharge opening (42) at the moment the flushing gas is supplied.

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.