Abstract: A compressor includes a bore, a rotor disposed within the bore, a compressor inlet, a compressor outlet and a compression chamber defined between the bore and the rotor. A volume of the compression chamber gradually reduces from the compressor inlet to the compressor outlet. An economizer is configured to fluidically connect to the compression chamber. The economizer is configured to inject a working fluid into the compression chamber at an injection position. The injection position is changeable according to a working condition of the compressor.

Abstract: A screw compressor has a slide valve movement mechanism that includes a cylinder provided in a casing body, a piston partitioning an interior of the cylinder into a first chamber and a second chamber, and a communication flow passage through which the second chamber communicates with a low-pressure space. The cylinder includes a first inflow hole, a second inflow hole, and a third inflow hole. The first chamber communicates with a high-pressure space through the first inflow hole, the second chamber communicates with the low-pressure space through the second inflow hole and the communication flow passage, and the second chamber communicates with the high-pressure space through the third inflow hole. The third inflow hole is located at a position at which the third inflow hole is closed by the piston when the piston lies at a stop position at which the piston moves toward the second chamber and stops.

Abstract: A rotary piston and cylinder device comprising a rotor (2), comprising a rotor surface (2a), a stator (4), a rotatable shutter (3), a piston (5) which extends from the rotor surface, the rotor surface and the stator together defining an annular chamber, and the piston arranged to rotate, through the annular chamber, and the rotor surface being orientated at an incline to a plane (P-P) substantially perpendicular to the axis of rotation (A-A) of the rotor and the rotor surface faces generally away from, or outwardly of, the axis of rotation of the rotor.

Abstract: A rotary piston and cylinder device (1) comprising a rotor (2), a stator (4), a rotatable shutter (3), the rotor and the stator comprising surface portions which define a chamber, wherein the rotor comprises a first surface portion (2A) and the stator comprises substantially two surface portions (4a; 4b?), and the two surface portions of the stator neighbour each other.

Abstract: A single-screw compressor includes a screw rotor with a helical groove, a cylindrical wall rotatably housing the screw rotor, a gap adjuster mechanism, and a gear-shaped gate rotor having a plurality of flat gates. The gate rotor is arranged outside the wall. Some of the gates enter a space inside the wall via an opening formed in the cylindrical wall and mesh with the screw rotor. A fluid is compressed in a compression chamber defined in the helical move by the screw rotor, the gates meshing with the screw rotor, and the wall. The gap adjuster mechanism avoids contact between a front surface of the gate rotor toward the compression chamber and a sealing surface of the wall facing the front surface, by displacing at least one of the gate rotor and the sealing surface of the wall in an axial direction of the gate rotor.

Abstract: A screw compressor includes screw and gate rotors, a cylindrical wall, and a slide valve including a valve body and a guide portion. The valve body extends in an axial direction of the cylindrical wall and has a crescent shape in a cross section in a perpendicular direction to the axial direction. A radius of curvature of an inner arc shaped curved surface of the crescent shape is substantially equal to a radius of curvature of an inner peripheral surface of the cylindrical wall. A radius of curvature of an outer arc shaped curved surface of the crescent shape is smaller than the radius of curvature of the inner arc shaped curved surface, and a central angle of the outer arc shaped curved surface is 180° or less. The guide portion allows movement of the valve body in the axial direction and restricts movement in the perpendicular direction.

Abstract: An engine includes a housing defining an annular bore and a piston assembly disposed within the annular bore. The engine also includes a rotary valve comprising a circular faceplate and a wall structure disposed at an outer periphery of the faceplate, a portion of the at least one rotary valve disposed within the annular bore, and a rotary drive mechanism connected to the rotary valve and configured to rotate the rotary valve between a first position to align an opening of the wall structure with the annular bore to allow the piston of the piston assembly to travel within the annular bore from a first location relative to the rotary valve to a second location relative to the rotary valve and a second position to define a chamber relative to the piston of the piston assembly at the second location.

Abstract: A cooling device having a centrifugal pump directly mounted on a radiator. An annular seal member is disposed between the bottom portion of the case body of the centrifugal pump and the side surface of the tank chamber of the radiator, and the annular seal member is used for preventing the cooling medium leakage via a space between the centrifugal pump and the tank chamber. The cylindrical portion of the case body and the annular seal member are overlapped with each other in the axial direction of the rotation center shaft of the motor that drives the centrifugal pump, in order that the cylindrical portion can receive at least a part of the reaction force of the annular seal member crushed between the case body and the tank chamber, and thereby the bottom portion of the case body of the centrifugal pump is prevented from deformation.

Abstract: A screw compressor includes a casing, a motor provided in the casing, a screw rotor inserted into a cylinder in the casing, a bearing holder, a drive shaft, a first bearing, and a second bearing. The cylinder is formed on a lateral side of the motor. The bearing holder is disposed on an opposite side of the screw rotor from the motor and adjacent to the screw rotor. The drive shaft is connected to the motor and the screw rotor. The first bearing is disposed adjacent to the screw rotor. The second bearing is disposed adjacent to the motor in an axial direction of the drive shaft. At least a portion of the first bearing is disposed inside the screw rotor.

Abstract: A positive displacement device that converts energy, namely positive displacement compressors that rotate in a single rotational direction to displace working fluid contained in operating chambers. The device described herein is particularity advantageous for the ability to achieve high compression ratios in combination with high discharge pressure and high volumetric throughput in a single stage.

Abstract: A rotary piston and cylinder device (1) comprising a rotor (2), a stator and a shutter disc (3), the rotor comprising a piston (5) which extends from the rotor into the cylinder space, the rotor and the stator together defining the cylinder space, the shutter disc passing through the cylinder space and forming a partition therein, and the disc comprising a slot (3a) which allows passage of the piston therethrough, the slot provided between two surface portions which receive the piston therethrough,at least one of the surfaces defines a close-running region with the piston to provide a fluid seal, and for at least part of the period during which the piston passes through the slot, the close-running region is offset from a mid-plane which extends through the disc and is co-planar with the disc.

Abstract: An anti-locking mechanism of a spherical compressor rotor, an anti-locking power mechanism of a spherical compressor, and a spherical compressor. A pin boss is fixedly arranged on a turntable shaft, and guide pins are movably connected with a guide sleeve. A concave slideway is arranged in a cylinder block spherical surface or a cylinder lower spherical surface, and is distributed along a sliding track of the guide sleeve on the corresponding cylinder block spherical surface or cylinder lower spherical surface in a rotation process of a turntable. A main shaft rotates and drives the turntable. When the turntable rotates to a position at which a turntable axis and a piston axis are superposed, the turntable can continue to rotate around the turntable axis by means of torque obtained by the guide pin from the concave slideway, and thus a problem of a dead point of movement of a spherical compressor rotor is solved.

Abstract: A rotary piston and cylinder device having a rotor, a stator and a shutter disc, the rotor including a piston which extends from the rotor into the cylinder space, the rotor and the stator together defining the cylinder space, the shutter disc passing through the cylinder space and forming a partition, and the disc having a slot which allows passage of the piston, the shutter disc having a circumferential surface that forms a seal with the rotor, the circumferential surface defining at least one close running line with the rotor, and the at least one close-running line offset from a rotor plane which lies on a radius of the rotor and which includes the axis of rotation of the rotor.

Abstract: An engine includes a housing defining an annular bore and a piston assembly disposed within the annular bore. The engine includes a rotary valve comprising a loop-shaped wall structure defining an opening substantially perpendicular to an axis of rotation of the loop-shaped wall structure. A portion of the rotary valve is disposed within the annular bore such that the axis of rotation of the loop-shaped wall structure is substantially perpendicular to an axis of rotation of the piston assembly. The engine includes a rotary drive mechanism connected to the rotary valve and configured to rotate the rotary valve between a first position to align the opening of the loop-shaped wall structure with the annular bore to allow a piston of the piston assembly to travel within the annular bore and a second position to define a combustion chamber relative to the piston of the piston assembly at the second location.

Abstract: A transmission assembly for a rotary piston and cylinder device, comprising a first gear (120) and a gear sub-assembly (15, 16, 17, 18, 19), the first gear connectable to a rotatably mounted shutter (12) of the device, and the first gear extending from a side of the shutter, and the first gear connected to the gear sub-assembly which converts rotation to an axis of rotation different to that of the shutter.

Abstract: Disclosed herein are several embodiments for shroud arrangements to be used in rotary engines using a plurality of rotors within the shroud arrangement. At least one of the rotors is not fixed to the shroud.

Abstract: Disclosed herein is an indexing system for a rotor assembly where in one example the indexing system regulates the rotational location of drive rotors. In one example the rotors are configured to rotate about a shaft.

Abstract: A feed unit comprising a first toothing part (1) and a second toothing part (2) which interact with one another via a toothing system (1.1, 2.1) and axes (1.2, 2.2) of which are set obliquely with respect to one another, the first toothing part (1) engaging around the second toothing part (2) with a collar section (8), and working spaces (3) being formed between the toothing system (1.1) of the first toothing part (1) and the toothing system (2.1) of the second toothing part (2), which working spaces (3) are configured to be filled via an inflow (4) and are configured to be emptied via an outflow (5).

Abstract: Provided herein are multiple variations, applications, and variations for producing electrical power from a flowing fluid such as a gas or liquid under pressure, for example natural gas flowing through a pipeline, by means of one or more positive displacement devices that drive one or more electrical generators. The electrical generators may be immersed in the flow stream together with the positive displacement devices as disclosed, or alternately may be isolated from the flow stream, such as by magnetic coupling, in order to promote longevity and to decrease the risk of accidental discharge or explosion of the fluid in the flow stream. To further decrease such risks, the positive displacement devices may isolate the drive fluid from the environment without the use of dynamic seals.

Abstract: In one aspect, a single screw compressor is disclosed. The compressor, in at least some embodiments, includes: a housing including a cylindrical bore; a pair of gate rotors mounted for rotation in the housing, each gate rotor having a plurality of gear teeth; and a main rotor rotatably mounted in the bore and having a plurality of grooves, a plurality of lands, an additional groove, and an additional land; wherein the plurality of lands of the main rotor comprises a first wrap angle and the additional land comprises a second wrap angle, and the second wrap angle is distinct and different from the first wrap angle. In other aspects, a method of assembling a gate rotor in relation to a main rotor that is positioned within a single screw gas compressor configured for high output, and a main rotor device for use with a single screw compressor configured for high output are also disclosed.

Abstract: A delivery unit is already known, which comprises a drive shaft and a rotor driven by the drive shaft. The rotor is rotatably arranged in a stator housing, wherein the rotor has a toothing on the end face of said rotor that is remote from the drive shaft, wherein said toothing meshes with a toothing constructed on the stator housing. The drive shaft comprises an oblique sliding plane interacting with the rotor and which is constructed on a shoulder of the drive shaft and allows the rotor to gyrate with the rotor axis thereof about the drive axis of the drive shaft. Work spaces are formed between the toothing of the rotor and the toothing of the stator housing, wherein said work spaces can be filled via an inlet and emptied via an outlet. In one embodiment the fluid is admitted axially and discharged radially, and in the other embodiment the fluid is admitted and discharged axially. For that purpose, control valves in the form of non-return valves are required.

Abstract: A screw compressor includes a rotatable screw rotor and a plurality of gate rotors. The screw rotor has helical grooves formed in an outer circumferential surface of the screw rotor. The gate rotors have a plurality of radially disposed teeth meshing with the grooves of the screw rotor. The helical grooves include a first screw groove and a second screw groove. The first screw groove compresses a fluid from one end side of the screw rotor to an other end side of the screw rotor. The second screw groove compresses the fluid from the other end side of the screw rotor to the one end side of the screw rotor.

Abstract: A screw compressor includes a screw rotor, a gate rotor, a drive mechanism to rotate the screw rotor, a cylinder, a discharge port and an adjustment mechanism. The screw rotor has an outer periphery with a helical groove engaged with radially arranged gates of the gate rotor. First and second axial ends of the screw rotor form suction and discharge sides, respectively. The cylinder accommodates the screw rotor to define a compression chamber in the helical groove. Fluid in the compression chamber flows through the discharge port toward the discharge side of the screw rotor. The adjustment mechanism is configured to adjust a compression ratio of the compression chamber within a predetermined range. The adjustment mechanism adjusts the compression ratio to a minimum compression ratio immediately before or when operation of the adjustment mechanism is stopped.

Abstract: A screw compressor includes a casing, a screw rotor, an oil sump containing lubricant oil, a lubrication passage and a flow rate controller. The screw rotor is inserted in a cylinder portion of the casing to form a fluid chamber. The screw rotor rotates to suck a fluid into the fluid chamber for compression. The lubrication passage supplies the lubricant oil in the oil sump to the fluid chamber due to a difference in pressure between the oil sump and the fluid chamber. The flow rate controller reduces a flow rate of the lubricant oil supplied to the fluid chamber in accordance with a decrease in operating capacity of the screw compressor.

Abstract: A screw compressor includes a screw rotor having a plurality of helical grooves, a casing containing the screw rotor and a gate rotor. The casing includes a discharge port on an inner peripheral surface of the casing. The gate rotor has gates meshing with the helical grooves of the screw rotor to compress gas in compression chambers to discharge the gas from the discharge port after being compressed. The compression chambers are defined by the helical grooves, the casing, and the gates. The discharge port is divided into a first port and a second port when two adjacent helical grooves of the plurality of helical grooves is open to the discharge port as a result of rotation of the screw rotor, with one of the two adjacent helical grooves being open in the first port and the other of the two adjacent helical grooves being open in the second port.

Abstract: A media delivery assembly in which a defined compensating pressure is established at the backs of included axially adjustable rotors and a control valve is provided for establishing the compensating pressure at a predetermined value between a pressure on the pressure side and a pressure on the suction side.

Abstract: A pump or motor for fluid or gaseous media comprising a shaft (4), which faces a working part (13) and has a common inclined sliding surface (14) with the same, whereby the working part (13) limiting the pump working spaces (12) wobbles in a positionally fixed housing (10).

Abstract: Disclosed herein is an indexing system for a rotor assembly where in one example the indexing system regulates the rotational location of drive rotors. In one example the rotors are configured to rotate about a shaft.

Abstract: A rotary piston engine comprises at least two rotors, a power component and a blocking component, which interact and have spur gearings, the number of teeth of which differs by one, the rotors and an engine housing accommodating the rotors delimiting working compartments. The rotors are twisted at a defined angle to each other. The power component is driven by and rotationally connected to an electric motor arranged on the same axis. The motor has an internal stator and an external rotor, the engine housing being directly connected to the motor. The engine housing has a supporting tube section projecting into and supporting the internal stator. The external rotor has a bell which encloses the internal stator and has a center drive shaft extending through the supporting tube section and rotationally connected to the power component, the drive shaft being mounted towards the inner wall of the supporting tube section.

Abstract: A screw compressor includes a screw rotor, a gate rotor and an injection mechanism. The screw rotor is provided with multiple helical grooves. The gate rotor is provided with multiple gates meshing with the helical grooves to form at least one compression chamber between at least one of the helical grooves and at least one of the gates. The compression chamber is configured and arranged such that refrigerant taken-in from a starting-end side of the helical groove is compressed and discharged from a dead-end side of the helical groove. The injection mechanism is configured and arranged to inject oil or refrigerant from a discharge hole of the injection mechanism into the compression chamber such that rotational torque is imparted in a direction in which the screw rotor is rotated at a time of compression.

Abstract: A slide for use in a single screw compressor is disclosed. The screw compressor is arranged to vent the flutes of its main rotor at all times, without having to provide a check valve in the discharge port of the main rotor casing. An additional outlet port in the casing vents gas from the discharge ends of the flutes into the body of the slide instead of to the discharge port. The vented gas is guided to an exit port of the slide, from where it can reach either the discharge port or the bypass port of the casing at all times during use of the compressor and under all loading conditions. The design of the disclosed slide further allows the use of an offset discharge port in the casing, in relation to the main rotor.

Abstract: The rotary engine includes a circular stator, a circular rotor rotating about the stator; the rotor and the stator being separated by a circular cylinder and at least one element with two flanges. The rotor includes two compression pistons attached to the inner surface of the rotor. These two pistons are located at the two extremities of a first diameter of the rotor and kept substantially in contact with the outer surface of the stator. The stator includes a recess at each extremity of a diameter. Each recess forms a compression chamber with the compression piston positioned at the end of the recess in the direction of rotation of the rotor and one of the flanges of the element with two flanges, referred to as the cylinder head flange. The motive force is applied to the compression piston when the pressure of the gases inside the compression chamber is suddenly increased to a predefined value.

Abstract: A positive displacement internal combustion engine with the strongest mechanism for converting thermal energy of combustion gases to rotational motion, being composed of a body with spherical combustion chamber, and three spatial eccentrics being placed in said spherical chamber. The mechanism is particularly suitable for heavily loaded detonation and homogeneous charge compression ignition engines.

Abstract: Combined booster and primary pump arrangements can be bulky and require separate supplies of purge gas and cooling water. In order to overcome this problem invention provides a vacuum pump in which two or more pumping mechanisms, i.e. the booster pump and main pump, are housed in the same stator. The invention further provides a vacuum pump stator comprising at least two operatively interconnected cavities, wherein at least two of the cavities each comprise at least one rotor-receiving portion shaped to receive two or more at least partially intermeshing rotors, and wherein an axis of a rotor-receiving portion of a first one of the cavities is offset with respect to an axis of a rotor-receiving portion of a second one of the cavities.

Abstract: The present invention relates to a rotor for a vacuum pump having a roots pumping mechanism, the rotor comprising at least two hollow lobes, each lobe having an outer wall which defines a lobe profile, a hollow cavity generally inward of the outer wall, and at least one strengthening rib located in the cavity to resist stress on the lobes generated during rotation.

Abstract: An indexing system for a rotor assembly where the indexing system can regulate the rotational location of drive rotors that are configured to rotate about a shaft in one form.

Abstract: A single-screw compressor includes a screw rotor including a spiral groove, a casing, and a gate rotor. The gate rotor includes a plurality of radial gates configured to mesh with the spiral groove. A clearance between one of the gates disposed in the spiral groove and a wall surface of a discharge side portion of the spiral groove is larger than a clearance between the gate disposed in the spiral groove and a wall surface of a suction side portion of the spiral groove. The wall surface of the discharge side portion of the spiral groove is a portion extending from a predetermined position of the spiral groove at a certain point in a compression phase to the terminal end of the spiral groove. The wall surface of the suction side portion of the spiral groove being a portion other than the discharge side portion.

Abstract: This disclosure relates to a new multiphase pump with low recirculated volume. This device discloses novel inlet/outlet porting. One of the disclosed improvements is to port the inlet and outlet through the back of the rotors. In the model shown there is only one lobe on the first rotor, and two lobes on the second rotor. The double lobe rotor has the ports provided thru the back, in the lowest point on the buckets between the lobes. If there were more lobes on the two rotors, then the ports would normally be provided in the rotor with the higher number of lobes, preferably in the lowest point on each bucket. The single lobe rotor shown has voids formed in the outer circumference in order to balance the rotor—however, any rotor with more than one lobe may be naturally balanced and these holes may be unnecessary.

Abstract: A screw compressor includes a screw rotor, a casing, a low pressure space, a bypass passage and a slide valve. The screw rotor is provided with a plurality of helical grooves forming fluid chambers. The casing includes a cylinder portion with the screw rotor disposed in the cylinder portion. The low pressure space is formed in the casing to receive a flow of uncompressed, low pressure fluid. The bypass passage is opened in an inner peripheral surface of the cylinder portion to communicate the fluid chamber with the low pressure space. The slide valve is slideable in an axial direction of the screw rotor to change an area of an opening of the bypass passage in the inner peripheral surface of the cylinder portion. An end face of the slide valve facing the bypass passage is inclined along an extending direction of the helical grooves.

Abstract: A single-screw compressor includes a casing, a screw rotor accommodated in the casing, a gate rotor, and a gate rotor supporting member rotatably supporting the gate rotor. The gate rotor includes a plurality of flat-plate-shaped gates formed in a radial pattern and meshing with a helical groove of the screw rotor. Fluid in a compression chamber defined by the screw rotor, the casing and the gates is compressed when the screw rotor is rotated. The gate rotor supporting member includes a gate supporting portion supporting each gate from a back surface side. The gate rotor and the gate rotor supporting member form a gate rotor assembly including a pressure introduction channel configured and arranged to introduce a fluid pressure on a front surface side of each gate into a gap between a back surface of the gate and the gate supporting portion.

Abstract: A pump or motor for fluid or gaseous media comprising a shaft (4), which faces a working part (13) and has a common inclined sliding surface (14) with the same, whereby the working part (13) limiting the pump working spaces (12) wobbles in a positionally fixed housing (10).

Abstract: A method for converting energy from compressed air into mechanical energy, and a compressed air motor therefor. The motor includes a shaft rotor and a counterpart rotor which intermesh with each other using trochoid toothing to effect rotation of a power takeoff shaft. Compressed air is used to operate the counterpart rotor which then operates the shaft rotor thereby converting the rotation of the shaft rotor or the power takeoff rotor into mechanical rotary energy.

Abstract: In one aspect, a single screw compressor is disclosed. The compressor, in at least some embodiments, includes: a housing including a cylindrical bore; a pair of gate rotors mounted for rotation in the housing, each gate rotor having a plurality of gear teeth; and a main rotor rotatably mounted in the bore and having a plurality of grooves, a plurality of lands, an additional groove, and an additional land; wherein the plurality of lands of the main rotor comprises a first wrap angle and the additional land comprises a second wrap angle, and the second wrap angle is distinct and different from the first wrap angle. In other aspects, a method of assembling a gate rotor in relation to a main rotor that is positioned within a single screw gas compressor configured for high output, and a main rotor device for use with a single screw compressor configured for high output are also disclosed.

Abstract: A screw compressor comprises a first meshing body and a second meshing body. The first meshing body has plural helical flutes disposed around a first rotating shaft. The second meshing body has plural projections or lobes disposed around a second rotating shaft. At least one of the projections or lobes is arranged non-uniformly with respect to the other projections or lobes in a circumferential direction of the second rotating shaft. The plural helical flutes are arranged to be meshable with the plural projections or lobes, in a circumferential direction of the first rotating shaft.

Abstract: The subject of the invention is a variable-volume rotary device with a housing (1) comprising an inner spherical cavity, inlet and exhaust ports and a bypass flow path. Within the housing (1) a rotary displacement member with spherical outer configurations capable of revolving around the center point of the spherical inner surface of the housing is mounted. Said rotary displacement member is equipped with a centrally disposed, disc-shaped partition (6) that forms a mutually isolated division in the spherical inner cavity of the housing (1) and has two pivot vanes (7, 8), splitting the housing cavity further into four isolated quadrants, the volume of which vary during gyration. Vanes (7, 8) are similar in shape to orange segments. Vanes (7, 8) are connected to opposing sides of and along the diameters of the central disc (6), and extend in mutually perpendicular planes, allowing for rotary movement.

Abstract: A screw compressor includes a casing, a screw rotor and a gate rotor. The casing has a cylinder. The screw rotor is cylindrical-shaped and configured to be fitted into the cylinder. The gate rotor is configured to be engaged with the screw rotor. A, outlet width of a seal surface of the casing on a gas-outlet side of the screw rotor is larger than an inlet width of the seal surface on a gas-inlet side of the screw rotor. The seal surface of the casing is opposed to one surface of the gate rotor.

Abstract: Delivery units are already known, having a drive rotor and an output rotor driven by the drive rotor, which are rotatably mounted in a rotor housing and interact in a meshing manner via spur toothing in each case, at least one of the two rotors being axially adjustable and, on the rear side thereof, facing away from the other rotor, having a compensating pressure applied via a compensation channel. The compensating pressure acts firstly counter to the axial compressive forces which arise in the working chambers formed between the rotors, and secondly compensates for the forces which would force the two rotors apart. This ensures that the distance between the rotors does not change. The compensating pressure frequently corresponds to the pressure on the pressure side of the delivery unit, which means that the forces on the rotors are considerably higher than necessary. This leads to increased friction in the bearings and between the rotors. The rear side of the rotors can also be supplied via slot flows.

Abstract: A screw compressor includes a casing, a screw rotor disposed in a cylinder portion of the casing to define a compression chamber, and a capacity control slide valve. Fluid sucked into the compression chamber is compressed by rotation of the screw rotor. The slide valve is slidable along a rotation axis of the screw rotor and is opposed to an outer circumferential surface of the screw rotor. The slide valve includes a dynamic pressure generator formed on an opposed surface of the slide valve that is opposed to the screw rotor to generate a dynamic pressure using fluid in contact with the opposed surface of the slide valve. The slide valve is configured so that the dynamic pressure generated by the dynamic pressure generator avoids contact between the slide valve and the screw rotor.

Abstract: In a screw rotor (40), a first suction-side area (45) is formed in a first side wall surface (42) of a spiral groove (41). In the first side wall surface (42), a portion extending from a start point to a point until immediately before a compression chamber (23) is in a completely-closed state defines the first suction-side area (45). The first suction-side area (45) is thinner than a portion of the first side wall surface (42) other than the first suction-side area (45), and does not contact a gate (51) of a gate rotor (50).

Abstract: In a single screw compressor, gates (51) of gate rotors (50) are to be engaged with spiral grooves (41) of a screw rotor (40). In each spiral groove (41) of the screw rotor (40), an area extending from a start point of the spiral groove (41) to a position in a compression stroke is a suction-side portion (45), and the remaining portion (portion up to a terminal point of the spiral groove (41)) is a discharge-side portion (46). In the discharge-side portion (46), a clearance between a wall surface (42, 43, 44) therein and the gate (51) is substantially “0 (zero).” A clearance between the wall surface (42, 43, 44) in the suction-side portion (45) and the gate (51) is wider than that between the wall surface (42, 43, 44) in the discharge-side portion (46) and the gate (51), and is gradually narrowed from the start point toward the terminal point in the spiral groove (41).