Abstract: According to one embodiment, a roots pump includes a first roots pump, a second roots pump, and a connection passage. The first roots pump includes a first casing which has a first pump chamber. The second roots pump includes a second casing which has a second pump chamber. The connection passage connects an exhaust hole which is provided in the first pump chamber to an intake hole which is provided in the second pump chamber.

Abstract: A dry pump includes: a plurality of cylinders; a pump chamber formed in each of the cylinders; a division wall separating pump chambers adjacent to each other; a plurality of rotors contained inside pump chambers; a rotating shaft that serves as an axis of rotation of the rotor; and a cooling medium path which is formed inside the division wall and through which a cooling medium passes.

Abstract: A screw rotor is for use in a screw pump that pumps fluid by rotation of a pair of screw rotors engaged with each other in a rotor housing. The screw rotor includes a multiple-thread portion for pump suction side and a single-thread portion for pump discharge side. The screw rotor is formed so that the tooth profile of the multiple-thread portion is connected to the tooth profile of the single-thread portion through a boundary plane that is perpendicular to the rotation axis of the screw rotor. The first curved portion coincides with the third curved portion in the boundary plane.

Abstract: A combustion engine, which is highly efficient, noiseless and lightweight, includes a combustion chamber without pistons. The combusted and expanded air exiting the combustion chamber flows into a displacement pump, such as a gear pump or radial vane pump. The displacement pump drives the load, and, in addition, another smaller displacement pump, which pressurizes fresh air and introduces same, via a feedback loop, into the combustion chamber. Gas or other burnable fuels are introduced in the combustion chamber, so that a continuous fuel burning will occur, after being ignited. The ratio of bigger to the smaller pump is influenced by the percentage of expansion of the air in the combustion chamber.

Abstract: A pressure equalization system reduces or eliminates a pressure differential across supercharger rotor shaft seals. Under high boost, rotor shaft seals often fail, allowing hot compressed air into an oil lubricated space containing rotor bearings and gears (and vented to ambient pressure), reducing oil lubricating effectiveness and resulting in increased wear and failure. Under low or non boost operation, the pressure differential is reversed causing the lubricating oil to leak into the supercharger interior and accelerated rotor seal wear. The pressure equalization system includes flow restrictive seals on both rotor shafts, separated from the rotor shaft seals by vented spaces, thereby isolating the rotor shaft seals from boost or vacuum in the supercharger interior and reducing or eliminating the pressure differential across the rotor shaft seals. Maintaining close to atmospheric pressure on both sides of the rotor shaft seals during boost and vacuum operation reduces wear and failures.

Abstract: An apparatus includes a rotation body having one or more rotary shafts having projections, and a cleaning part disposed adjacent to the projections, having one or more rotation holes into which the one or more rotary shafts are inserted, respectively, and configured to flow a cleaning material into the one or more rotation holes.

Abstract: A high-pressure pump for supplying fuel to an internal-combustion engine has a pump body and an actuating shaft which extends along a longitudinal axis and which is supported rotatably about the longitudinal axis by the pump body. The shaft has an eccentric portion and a prismatic jacking end. A first pumping station has a gear engaged with the prismatic jacking end and a second pumping station has at least one piston. The piston is slidable relative to the pump body transversely with respect to the longitudinal axis and is actuated by the eccentric portion of the actuating shaft. The prismatic jacking end is made of a harder material than the material with which the remainder of the actuating shaft is made.

Abstract: A multistage vacuum pump has a pair of rotors disposed in each of pump chambers connected in stages. As the rotors rotate while intermeshing, a suctioned gas is compressed and discharged, angles of the rotors are adjusted so that a phase angle ?? of the rotors of adjacent pump chambers relative to a rotation angle C of the rotors during a single cycle of the pump chambers from intake to discharge and the number of stages S of the rotors satisfies ???C/S. When a rotor angle is ?1, an mth stage rotor angle is ?m, and an nth stage rotor angle is ?n in order from an upstream side of a gas flow direction, relationships of ?1<?m??n and ?1<?n, where n and m are natural numbers and n>m, are satisfied.

Abstract: The present invention provides a dry pump including: a center cylinder which includes: a plurality of pump chambers containing an upper stage pump chamber that communicates with an intake port and a lower stage pump chamber that communicates with a discharge port; a plurality of rotors contained in the plurality of the pump chambers; a rotating shaft that is a rotation axis of the rotor; and a side face on which a communication hole is formed, the side face being intersected by the rotating shaft extending in the axial direction, and being provided adjacent to the lower stage pump chamber, and a side cover which covers the side face with the communication hole to form a space.

Abstract: A balance shaft module equipped with a dual pump including a main oil pump and a sub-oil pump may include a pump rotor rotatably coupled to a housing, a discharge space formed in the housing for discharging oil in the sub-oil pump, a pulse chamber formed in the housing to increase the discharge space, wherein the oil discharged through the discharge space is merged with the oil flowing through the pulse chamber such that discharge pulse pressure is reduced, and an eccentric washer having a discharging opening space formed by cutting off a portion inward from the outside, wherein the discharge opening space of the eccentric washer is connected to the discharge space to fluid-communicate with the discharge space of the pump rotor.

Abstract: A Roots vacuum pump stator is arranged to house a pair of intermeshing rotors, said stator being characterized in that it comprises a director or deflector arranged to direct solid material entrained in a gas pumped through the pump towards the outlet. In other words, the stator according to the present invention has a means for directing or deflecting powder or solid material entrained in a gas being pumped directly towards an outlet of the pump or out of the pump. The directing means can comprise a channel disposed between the arcuate surface and the outlet, said channel comprising a portion that engages the arcuate surface prior to the bottom-dead-centre position and which extends away from the rotor's axis of rotation towards the pump outlet.

Abstract: A vacuum pump housing comprises first (12) and second half-shell stator components (14) defining a plurality of pumping chambers separated by partition members (26, 28, 30, 32). Each pumping chamber comprises an inlet port (42, 44, 46, 48, 50) for receiving fluid and an outlet port (54, 56, 58, 60, 62) through which pumped fluid is exhausted from the chamber. The inlet ports are open on an external surface of the first stator component, and the outlet ports are open on an opposing external surface of the second stator component. The stator components further define transfer channels (66, 68, 70, 72) for conveying fluid between the pumping chambers. Each transfer channel preferably comprises first and second portions located on opposite sides of the housing.

Abstract: An air supply system is provided that uses two sets of rotors on a common set of shafts to boost air in two stages. The air supply system includes a housing and a first and a second rotatable shaft at least partially within the housing. A first and a second pair of rotors are included. Each pair of rotors has a first rotor supported for rotation on the first shaft and a second rotor supported for rotation on the second shaft. The housing has an inlet at the first pair of rotors, an outlet at the second pair of rotors, and an internal chamber between the first and the second pairs of rotors. Air flow from the inlet to the outlet thereby has a first pressure boost from the inlet to the internal chamber and a second pressure boost from the inlet chamber to the outlet.

Abstract: A screw compressor has a balance bearing whose outer ring is movable relative to the casing. A balance piston divides a balance cylinder into a high pressure fluid chamber and a low pressure fluid chamber, and movement of the piston in the balance cylinder is transmitted to the outer ring of the balance bearing. The high pressure fluid chamber and the low pressure fluid chamber are arranged such that higher pressure fluid in the high pressure fluid chamber urges the piston to press the outer ring of the balance bearing oppositely to a spring and toward the main thrust bearing, and lower pressure fluid in the low pressure fluid chamber urges the piston to press the outer ring of the balance bearing away from the main thrust bearing.

Abstract: A two-stage medium-pressure screw air compressor comprises a primary screw compressor (21) and a secondary screw compressor (22) communicating with the gas-liquid separator (6) via the first gas-liquid inlet (61). A first oil outlet (63) is connected to a mid section of a gas-liquid separator (6). The oil is injected into the lubricating components of the compressor is the first oil outlet (63), a first filter (64). A secondary oil-water separator (9) is connected to the first oil outlet (63) of the gas-liquid separator (6), the second oil-water separator (6) has an upper separating tank (91) and a lower separating tank. The water and the impurities contained in the lubricating oil can be eliminated at a largest extent, so as to create essential condition thr ensuring the screw compressor to operate continuously, stably and safely and provide high operational reliability, safety and long service life.

Abstract: A housing of a Roots pump is configured by joining a lower housing member and an upper housing member that are separable from each other. With the upper and lower housing members joined together, an upper accommodating portion and a lower accommodating portion form a front bearing accommodating portion and a rear bearing accommodating portion, which accommodate whole bearings, respectively. The Roots pump further includes bearing holders attached to the bearings and fixed to the lower housing member so that the bearings are received in the lower accommodating portion in a positioned state.

Abstract: The invention relates to a multi step helical screw compressor unit which consists of a drive housing (90), wherein a first, second, and third helical screw compressor (60, 70, 80) are secured in a protruding manner parallel to each other and are driven together by a drive toothed wheel in the drive housing. A gas-like fluid is compressed by the first helical screw compressor (60) at a first intermediate pressure of approximately 3.5 bars, by the second helical screw compressor (70) at a second intermediate pressure of approximately 12 bars and by the third helical screw compressor (80) at an end pressure of approximately 40 bars. The driven toothed wheels (65, 75) of the first and the second helical screw compressors are in contact with the drive toothed wheel (95) above the axes thereof, when the driven toothed wheel (85) of the third helical screw compressor (80) is in contact with the drive toothed wheel (95) in the vicinity of the deepest point thereof (T).

Abstract: An axial flow positive displacement gas turbine engine component such as a compressor or a turbine or an expander includes a rotor assembly extending from a fully axial flow inlet to a downstream axially spaced apart axial flow outlet. The rotor assembly includes a main rotor and one or more gate rotors rotatable about parallel main and gate axes of the main and gate rotors respectively. The main and gate rotors having intermeshed main and gate helical blades extending radially outwardly from annular main and gate hubs, circumscribed about, and wound about the main and gate axes respectively. Intersecting main and gate annular openings in the axial flow inlet extend radially between a casing surrounding the rotor assembly and the main and gate hubs. The main helical blades transition from 0 to a full radial height in a downstream direction in an inlet transition section.

Abstract: A rotor assembly for a multi-stage pump is provided. The assembly includes a drive shaft, a rotor component and a drive component. The rotor component is located on the drive shaft and includes a rotor element for displacing fluid through the pump when the drive shaft is rotated. The drive component is anchored to the drive shaft and transmits torque from the drive shaft to the rotor component to effect rotation of the rotor component. A sleeve element is integrated with either the drive component or the rotor component and is used to space the rotor element from the drive component. An interface surface is located on the sleeve element for interacting with the other one of the drive component and the rotor component in order to maintain orthogonal alignment between the rotor element and the drive shaft. A driver is provided for transmitting torque between the drive component and the rotor component.

Abstract: A blending pump assembly for accurately maintaining the proper ratio of two fluid components. Flow of a first fluid is utilized to drive a fluid motor, which in turn drives a pumping mechanism to inject a proportional amount of a second fluid into the flow of the first fluid. The fluid motor and pump are sized so that a predetermined ratio between the two fluids is maintained regardless of changes in pressure and flow rate of such first fluid.

Abstract: A braking controller of a three-phase permanent magnetic brushless DC motor for directly driving a screw pump includes a detection circuit for detecting power supply states of the three-phase permanent magnetic brushless DC motor and a braking circuit for controlling the braking startup according to the power supply states of the three-phase permanent magnetic brushless DC motor. When the motor is supplied with power, the braking circuit is cut off. When the motor is not supplied with power and the screw pump drives the motor to reverse, the braking circuit starts up.

Abstract: A two-stage screw compressor has a low-pressure stage screw compressor and a high-pressure stage screw compressor integrally constructed. Compression space is formed by a male rotor and a female rotor, and operation gas is fed for compression to the compression space. A method of supplying lubrication oil prevents degradation of volumetric efficiency caused by return of lubrication oil, coming from a bearing and a shaft sealing device, to the low-pressure stage screw compressor. As a result, refrigeration capacity is improved and the amount of the lubrication oil is reduced.

Abstract: A multi stage vacuum pump for pumping corrosive fluid with a first flow section of material less resistant to corrosion than the material of a second flow section downstream of the first flow section.

Abstract: Rotary piston steam engine with equal double rotary pistons is provided with a balanced rotary variable inlet cut-off valve for enhanced efficiency. The exhaust steam from the primary expansion is routed to secondary expansion avoiding back pressure for additional efficiency. The rotary valve has balanced dual inputs and outputs on opposite sides. The exhaust steam from the primary expansion is taken off when the trailing face of the rotary piston passes the inlet port of the expansion chamber housing, the exhaust outlet secondary expansion being placed approximately 180 degrees from the primary expansion inlet in the curved portion of the expansion chamber housing wherein back pressure is not imparted to the primary expansion.

Abstract: A lubricating pump having a first stage and a second stage; the first stage in turn has an intake connectable hydraulically to a tank of lubricating fluid, and a delivery outlet connectable hydraulically to a lubricated member; the first stage compresses the lubricating fluid from the tank to a pressure for supply to the member; the second stage in turn has an inlet connectable hydraulically to a casing housing the member, and an outlet connectable hydraulically to the tank; the second stage feeds the lubricating fluid in the casing back into the tank; the second stage is a Roots type, and has a first and a second rotor rotating about respective axes to feed the lubricating fluid from the inlet to the outlet; and the first and second rotor are operated by the first stage.

Abstract: A variable output assembly including a hydraulic pump disposed on a pump running surface located on a center section, end cap or other hydraulic mounting member. The pump may be a gerotor or other rotatable pump body. A support member is disposed between the pump running surface and the pump and includes a pump support surface having openings to permit fluid communication between the support member and the pump running surface. A motor assembly may be hydraulically connected to the pump running surface by a first porting system, and a sump is hydraulically connected to the pump running surface by a second porting system. The support member is movable between neutral and a plurality of positions corresponding to forward and reverse directions of the output.

Abstract: A multistage pump (4) comprises: a plurality of components (50, 60, 70, 80, 90, 100, 110) comprising a plurality of pre-assembled pump modules (70, 90, 110) including at least one twin screw pump module (1, 2); characterised in that the multistage pump (4) further comprises an elongate sleeve (41) for housing the components (50, 60, 70, 80, 90, 100, 110); and securing means (42a, 42b) attachable or engagable with a portion of the elongate sleeve (41), the securing means (42a, 42b) being operable to fixedly retain the components (50, 60, 70, 80, 90, 100, 110) within the sleeve (41).

Abstract: A roots type fluid machine includes a case having a side wall, a pair of rotary shafts provided in the case, a pair of rotors engaged with each other and fixed to the pair of rotary shafts so as to extend axially, respectively, a suction space formed by the case and the pair of rotors for introducing fluid, a discharge space formed by the case for discharging fluid and the pair of rotors and a transfer chamber formed by the case and the rotor. The rotor has a rotor end surface. A clearance is formed between the side wall and the rotor end surface. The transfer chamber transfers gas introduced in the suction space to the discharge space in accordance with the rotation of the pair of rotors. The case has a guide groove formed in the side wall facing the rotor end surface. Gas leaked from the discharge space into the clearance is introduced to the transfer chamber through the guide groove.

Abstract: A multistage vacuum pump includes a stator housing a multistage rotor assembly, each stage having intermeshing Roots rotor components, wherein the tip radius of the rotor components at an inlet stage of the pump is larger than the tip radius of the rotor components at an exhaust stage of the pump, wherein a meshing clearance between the rotor components at the inlet stage of the pump is greater than a meshing clearance between the rotor components at the exhaust stage of the pump.

Abstract: Provided is a vacuum pump having a rotation body cleaning unit. The vacuum pump includes a case provided with rotation guide holes at opposite end parts. The case includes a rotation body placed inside the case and including a rotation shaft having opposite ends rotatably supported by the rotation guide holes and a number of lobes provided in the rotation shaft at predetermined intervals. Further, a cleaning part is supported by the case and placed in a space between the lobes and cleans the rotation body.

Abstract: A screw pump and pumping arrangement including a screw pump having a chamber and externally threaded rotors mounted on shafts for counter-rotation and flow paths with fluid inlets located at a common low pressure side of the chamber.

Abstract: A dry pump includes: a plurality of cylinders; a pump chamber formed in each of the cylinders; a division wall separating pump chambers adjacent to each other; a plurality of rotors contained inside pump chambers; a rotating shaft that serves as an axis of rotation of the rotor; and a cooling medium path which is formed inside the division wall and through which a cooling medium passes.

Abstract: An oilless screw compressor incorporating water-cooled cooling units for cooling compressed air discharged from compressor bodies having a pair of male and female screw rotors which can be rotated in a contactless and oilless manner, the cooling units comprising a plate type heat-exchanger, and the amount of cooling water for the plate type heat-exchanger being adjustable. With this configuration, a difference between a temperature during load operation and a temperature upon automatic stopping and during unload operation of the compressor can be reduced, so that the cooling unit can be restrained from being damaged or broken within a short period, thereby it is possible to provide a highly reliable oilless screw compressor.

Abstract: An oil pump for an internal combustion engine for drawing up the lubricating oil situated in an oil collector device has an oil pump housing wherein at least two pairs of gears are disposed. The pairs of gears, in order to form the pumping stages, are connected on the suction side to a suction passage formed in the oil pump housing and on the delivery side to a delivery passage. The oil pump housing is further formed with an oil supply passage that is connected to the suction passage of a first pumping stage and via which lubricating oil can be delivered to the suction side of the first pumping stage.

Abstract: The invention relates to a rotary lobe pump for conveying solids-laden fluids engendered in agriculture, in which the conveyed fluid volume flow adapts itself to different operating modes. For improved self-priming, the rotary lobe pump is preferably designed for vertical mounting of the rotary lobes, wherein an angular gear is provided. The rotary lobes are mounted in a topside or underside cover, wherein the axes of the rotary lobes are vertically oriented. Using one of the covers, the rotary lobes can be vertically removed and maintained without having to dismantle other pump components from the pump housing. The rotary lobes can also be removed together with the angular gear as an integral pump component using one of the covers.

Abstract: A water-cooled oil-free air compressor which features compactness and ensures improved productivity and maintainability. The compressor is an oil-free screw compressor which includes a low pressure stage compressor body, an intercooler for water-cooling the compressed air discharged from the low pressure stage compressor body, a high pressure stage compressor body for further compressing the compressed air cooled by the intercooler, and an aftercooler for water-cooling the air discharged from the high pressure stage compressor body. The intercooler and aftercooler each have a plurality of units, all of which are almost equal in shape. A cooler header on each or either of the inlet and outlet sides for compressed air is shared by the units of each cooler.

Abstract: A fluid pump (10) or motor (100) includes a pair of enmeshed tapered rotors (22,24,122,124) having intersecting axes of rotation. The first rotor (22,122) includes a small low pressure end (34,54,134,154) and a larger high pressure end (32,52,132,152) and a spiral thread (36,56,136,156) that increases in width and depth as it progresses from the high pressure end (28,128) to the low pressure end (26,126). The second rotor (24,124) enmeshes with the first rotor (22,122), and has an identical structure, except that its threads (36,56,136,156) progress in the opposite direction. Both rotors (22,24,122,124) are mounted on sliding splines (42,62,142,162) which permit them to move, to a limited extent, into and out of their respective receiving cavities.

Abstract: A multi-stage dry pump includes: a plurality of pump chambers each including a cylinder and a rotor housed in the cylinder; a first rotor shaft that is a rotation shaft of the rotors; a fixed bearing that rotatably supports the first rotor shaft and restricts a movement thereof along an axis direction of the first rotor shaft; and a free bearing that rotatably supports the first rotor shaft and permits a movement thereof along the axis direction of the first rotor shaft; wherein: the plurality of pump chambers is disposed between the fixed bearing and the free bearing; and a first pump chamber of the plurality of pump chambers which has a lower pressure and on the aspiration side is placed in proximity to the fixed bearing.

Abstract: A vacuum pump comprises two stator components (10, 14) and a seal (20) located between the components to provide a fluid-tight seal between the components. In one embodiment, the seal comprises a compliant annular body (24), an annular reinforcing member (26) embedded within the annular body, and a coating (28) of FFKM elastomer.

Abstract: The invention pertains to a dry vacuum pump comprising at least one rotating shaft (11) mounted on at least one lubricated bearing (5) and at least one sealing device (9) for sealing off lubricating fluids capable of entering the shaft passage from said bearing (5), said sealing device (9) being installed between the lubricated bearing (5) and a dry pumping stage (7), characterized in that said sealing device (9) comprises a centrifuge element (17) designed to rotate in unison on said shaft (11) and comprising at least one through line (19) capable of separating the lubricating fluids from the fluid that may travel from said bearing (5) to the dry pumping stage (7).

Abstract: A hydraulic pump is disclosed. The hydraulic pump may have a first fluid section (12), a second fluid section (14), and an input shaft (16) extending through the first fluid section and the second fluid section. The input shaft may have a first end (44), a second end (46), and a mid-portion (48) located between the first and second ends. The hydraulic pump may also have a first bearing (30) configured to continuously support the first end of the input shaft, and a second bearing (32) configured to continuously support the second end of the input shaft. The hydraulic pump may further have a third bearing (56) configured to intermittently support the mid-portion (58) of the input shaft.

Abstract: In an embodiment, a vacuum pump is capable of preventing adhesion of by-products to its surfaces. The vacuum pump includes a stator. The stator includes a cylinder wall and a pair of diaphragms disposed at opposite ends of the stator. A rotary shaft passes through the diaphragms, and a lobe is attached to the rotary shaft in the stator. The lobe may include a fluid port, and the fluid port may be disposed in sidewalls of the lobe to face the diaphragms. The rotary shaft may include a fluid supply path in communication with the fluid port.

Abstract: In a screw vacuum pump 30, equal lead screws each in the range of 1 to 4 leads are added on the discharge side of male and female screw rotors (4) and (5) having a continuously changing screw gear helix angle, at a final lead angle of the male and female unequal lead screw rotors on the discharge side that continuously change in helix angle following the advance of the screw gear helix.

Abstract: A multistage vacuum pump comprises a stator housing a multistage rotor assembly, each stage comprising inter-meshing Roots rotor components, wherein the tip radius of the rotor components at an inlet stage of the pump is larger than the tip radius of the rotor components at an exhaust stage of the pump.

Abstract: The rotary vacuum pump includes a pump housing, a rotary shaft, a thrust movement restriction mechanism and a first elastic member. The pump housing has therein a pump chamber. The rotary shaft has thereon a rotor rotatably disposed in the pump chamber. When the rotor is rotated with the rotary shaft, gas in the pump chamber is pumped thereby to draw gas into the pump chamber. The thrust movement restriction mechanism is provided for allowing the rotor to displace in the pump chamber in one thrust direction due to thermal expansion thereof during the operation of the rotary vacuum pump. The first elastic member is provided for urging the rotary shaft in the other thrust direction opposite to the one thrust direction.

Abstract: An oil pump for a compressor is provided. The oil pump includes a pump body, a driving shaft coupled to the pump body, with a supply passage extending therethrough, and a plurality of pumping members which rotate with the driving shaft. Fluids such as oil are inhaled into the pump through various intakes, and the inhaled oil is directed towards the driving shaft, where the oil is supplied to the friction parts of the compressor for lubrication. The plurality of intakes into the pump provide for a continuous supply of oil to the friction parts.

Abstract: A vacuum pump housing comprises first (12) and second half-shell stator components (14) defining a plurality of pumping chambers separated by partition members (26, 28, 30, 32). Each pumping chamber comprises an inlet port (42, 44, 46, 48, 50) for receiving fluid and an outlet port (54, 56, 58, 60, 62) through which pumped fluid is exhausted from the chamber. The inlet ports are open on an external surface of the first stator component, and the outlet ports are open on an opposing external surface of the second stator component. The stator components further define transfer channels (66, 68, 70, 72) for conveying fluid between the pumping chambers. Each transfer channel preferably comprises first and second portions located on opposite sides of the housing.

Abstract: A helical screw compressor includes two rotors which are mounted in the rotor housing. The helical screw compressor includes sealing arrangements (11, 11?) for sealing the pressure-sided shaft journals of the rotors. Each sealing arrangement includes a plurality of annular seals (11a, 11b) which are arranged in a row adjacent to each other, and an annular-shaped discharge chamber (51) is associated with the system on an intermediate position and is connected, via a discharge channel (53), to the chamber in the rotor housing, wherein pressure which is higher than the atmospheric pressure. Preferably, the discharge channel is connected to the suction chamber (10) of the rotor housing (1), and is impinged upon by precompressed gas from an upstream compressor step.

Abstract: The invention downsizes and simplifies structures of a compressor and its driving system apparatus, and achieves a reduction of a noise. An oil free screw compressor is constituted by compressor main bodies compressing a gas, a motor driving rotors of the compressor main bodies via step-up gears, a gear casing storing the step-up gears, cooling apparatuses cooling a discharge air and the like. An oil tank is provided independently from the gear casing, the motor is fixed to a common base, the gear casing is integrally attached to the motor via a flange, and the compressor main bodies are integrally attached to the gear casing via the flange. Further, the cooling apparatuses are arranged in an upper side of the driving system apparatus, and a cooling fan is installed in an upper side thereof.

Abstract: A two-stage screw compressor has a low-pressure stage screw compressor and a high-pressure stage screw compressor integrally constructed. Compression space is formed by a male rotor and a female rotor, and operation gas is fed for compression to the compression space. A method of supplying lubrication oil prevents degradation of volumetric efficiency caused by return of lubrication oil, coming from a bearing and a shaft sealing device, to the low-pressure stage screw compressor. As a result, refrigeration capacity is improved and the amount of the lubrication oil is reduced.