Abstract: A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

Abstract: A delivery port of a rotary-screw compressor includes a first opening having a profile configured to interrupt communication with a second working chamber of a suction process that opens only in the axial direction; a second opening connected to the first opening; and a third opening connected to the first and second openings. The profile of the first opening includes a first profile line that forms one of a pair of lateral edges of a lingulate protrusion; a second profile line that forms another one of the pair of the lateral edges of the protrusion; a third profile line that extends toward the reference point along the root circle of the female rotor; and a second connection line that connects the first and second profile lines. The second opening opens into the first opening at the second connection line. The third opening opens into the first groove.

Abstract: A screw compressor includes plural screw rotors, plural suction-side bearings that each rotatably support the suction side of the plural screw rotors and plural discharge-side bearings that each rotatably support the discharge side of the plural screw rotors, and a casing that houses the plural screw rotors, the plural suction-side bearings, and the plural discharge-side bearings. Each screw rotor includes a lobe section with plural lobes and a suction-side shaft section and a discharge-side shaft section each disposed at both ends of the lobe section. The casing has a housing chamber that houses the lobe sections of the plural screw rotors and a lubrication path in which liquid that lubricates the plural suction-side bearings circulates. In the lubrication path, respective passages to lubricate each of the plural suction-side bearings are connected in series and a most downstream part is connected to the housing chamber.

Abstract: Provided is a rotor structure of a screw compressor and an inverter screw compressor with the same. The rotor structure includes: a female rotor including a female rotor body, wherein the female rotor body includes a plurality of female teeth, and a tooth profile is formed between tooth crests of two adjacent female teeth of the female rotor body, and the tooth profile is formed by sequentially connecting an arc segment a1b an envelope bc, an arc segment cd, an arc segment de, an arc segment ea2, an arc segment a2a3 from front to rear along a counterclockwise direction, wherein centers of the arc segment cd and the arc segment de are respectively located on both sides of the tooth profile.

Abstract: Positive displacement machine such as a compressor, expander, pump or the like, for displacing a gaseous or liquid medium, the machine containing an element with at least one inlet and at least one outlet for the medium and at least two cooperating driven moving parts. The mutual periodic movement of the moving parts displaces the medium from the inlet to the outlet. Each of the at least two driven cooperating moving parts is provided with its own individual drive. The element is provided with a kinematic synchronisation coupling between the at least two cooperating moving parts for the mutual kinematic synchronisation of their movements.

Abstract: A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

Abstract: A screw pump, including a housing with a running bore having at least two intersecting bores, each of which receives a spindle, wherein the spindles have worm screw profiles which intermesh in portions and in operation bend in a defined bending direction under a hydraulic bending pressure, wherein each bore is configured as a slot with a longer first axis of symmetry and a shorter second axis of symmetry standing orthogonally thereto, wherein the longer first axis of symmetry runs in the bending direction.

Abstract: Systems and Methods for Differential Pressure Determination and Control are disclosed. In one aspect, embodiments of the present disclosure include a system, which able to obtain pressure measurements. The system can include, a sensor and a processor coupled to the sensor. A further embodiment includes memory coupled to the processor where the memory has stored thereon instructions, which when executed by the processor, cause the processor to: determine, a local set of pressure measurements from the sensor and/or compare the local set of pressure measurements with an external set of pressure measurements.

Abstract: A vacuum pump screw rotor, comprising at least two helical displacer elements on a rotor shaft. The at least two displacer elements have different pitches, but the pitches of each displacer element are constant. Furthermore, the displacer elements each have a helical recess, each having a contour that remains the same over its entire length. Hereby, a suction-side displacer element has a recess having an asymmetric contour, and a pressure-side displacer element has a recess having a symmetrical contour.

Abstract: A screw-spindle pump comprising: first and second screw spindles forming running and drive spindles, respectively, and a pump housing configured to receive the first and second screw spindles. The first and second screw spindles form, with at least the pump housing, delivery chambers, moving from a suction side to a pressure side of the pump as a consequence due to rotation of the screw spindles. The pump housing has an elongate insert, as an abutment for the first and second screw spindles and against which the first and second screw spindles are supported, the elongate insert having a first portion forming a first abutment for the second screw spindle and a second portion forming a second abutment for the first screw spindle. The elongate insert is clamped into a receptacle of the pump housing using a cross-sectional dimension of the elongate insert.

Abstract: The invention relates to a continuously variable transmission and a transmission system comprising said continuously variable transmission, wherein the continuously variable transmission comprises a first gear pump and a second gear pump, wherein each gear pump comprises a first gear and a second gear meshing with the first gear over an overlap distance in an overlap direction parallel to the first gear axis, wherein each gear pump further comprises an adjustment member for adjusting the pump volume, wherein the adjustment member of the first gear pump and the adjustment member of the second gear pump are interconnected by a connecting member for adjusting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation to each other.

Abstract: A rotor pair for a compressor block of a screw machine includes a secondary rotor that rotates about a first axis and a main rotor that rotates about a second axis. The number of teeth of the main rotor is 3 and the number of teeth of the secondary rotor is 4. The relative profile depth of the secondary rotor is at least 0.5 rk1 is an addendum circle radius drawn around the outer circumference of the secondary rotor and rf1 is a dedendum circle radius starting at the profile base of the secondary rotor. The ratio of the axis distance of the first axis from the second axis and the addendum circle radius rk1 is at least 1.636.

Abstract: In an oil-cooled screw compressor, a tooth crest arc of a fixed width is provided to the tooth crest of a male tooth profile, and simultaneously a tooth bottom arc is provided to the tooth bottom of a female tooth profile. Due to the actions thereof, the operation chamber immediately before disappearing exists only in a bottom half region from a line that connects the centers of the male and female tooth profiles, and the opening area relative to the volume of the operation chamber can be increased. As a result, the discharge of oil becomes smooth and energy loss is reduced.

Abstract: An oil-injected vacuum pump element, where two mating helical rotors are rotatably provided in a housing, where this housing includes an inlet port and an outlet end face with an outlet port, where compression chambers are formed between the helical rotors and the housing. The vacuum pump element is provided with a connection that extends from a first compression chamber to a second smaller compression chamber at the outlet end face, where this first compression chamber is at a lower pressure than the second compression chamber and where this second compression chamber can make connection with the outlet port upon rotation of the helical rotors, where the connection is such that a flow from the second compression chamber to the first compression chamber is possible, where the connection is not directly connected to the outlet port.

Abstract: A pair of co-operating screw rotors including a male rotor and a female rotor. The male rotor and the female rotor have helically extending lobes and intermediate grooves configured to intermesh with one another. Each groove of the female rotor has a first flank including at least three concave sections. A first section includes or is disposed immediately adjacent the radially innermost point of the groove. A second section is shaped as a circular arc with a radius having its center located outside the pitch circle. A third section is shaped as a circular arc with a radius having its center located outside the pitch circle. The radius of the third section is greater than the radius of the second section, which is greater than the radial distance between a pitch circle of the female rotor and the radially innermost point of the groove.

Abstract: Disclosed are rotary positive displacement machines capable of acting as an engine and as a pump, serving to improve the profile of working members of helical rotary engines, compressors and pumps. An actuator is comprised of a pair of rotors having engaged helical teeth. The rotors are disposed in chambers which encircle both. The working areas of the profiles of the teeth in an engaged pair are delineated in cross-section by portions of a cycloidal curve for one rotor and by arcs of circumferences which are eccentrically offset from the axis of the second rotor. Such a profile of teeth produces an eccentrically cycloidal engagement capable to work efficiently at very high rotor rotation speeds. The presence of power contact and low sensitivity to gearwheel skews allow for working with nonhomogeneous media, including those containing solid inclusions.

Abstract: A method of machining, with a formed tool, a first rotor and a second rotor with mutually complementary meshing threads involves rotating a first workpiece about a longitudinal axis of the workpiece. The tool makes one or more passes along the longitudinal axis of the workpiece as the workpiece rotates so as to remove material, thereby forming the flanks of each helix of the first rotor's thread. The value of at least one of the parameters that collectively define the relative position and relative movement of the workpiece and formed tool is varied during each pass so as to vary the lead of the thread. The above steps are repeated for a second workpiece, thereby forming the second rotor. Adjustments are made to at least one of said parameters during one or more of the passes in order to maintain mutually complementary shapes of the threads of the rotors.

Abstract: A reduced noise screw expander is described, which comprises a main rotor and a gate rotor each having an ‘N’ profile. The rotors are designed so that the torque on the gate rotor caused by pressure forces is in the same direction as the torque on the gate rotor caused by frictional drag forces. A method of designing a screw machine exhibiting reduced noise is also described. The screw machine has two or more rotors having an ‘N’ profile, and the method involves determining a ratio r/r1, where r is the main rotor addendum and r1 is the radius of the rack round side, and ensuring that this ratio is greater than 1.1 where the screw machine is to be a screw compressor or less than or equal to 1.1 where the screw machine is to be a screw expander.

Abstract: The objective of the present invention is to reduce a meshing seal line length and further reduce a blowhole area. A compression side blowhole B2 is generated in a region surrounded by a male rotor side blowhole contour R1, a female rotor side blowhole contour R2, and a lower cusp line k2. By configuring a female rotor side blowhole contour R3 with a curve including at least two arcs C1 and C2, an area of the compression side blowhole B2 may be reduced. At a connection point between arcs, by making tangents of the arcs on both sides across the connection point to be the same gradient, the arcs may be smoothly connected.

Abstract: A gear pump has a toothed driving wheel, a toothed driven wheel, a front flange from which a projecting portion of the shaft protrudes, being connected to the shaft of the driving wheel, a back lid fixed to the case, and an intermediate flange between the case and the front flange. The intermediate flange has first and second chambers connected by a connection duct to the inlet or outlet fluid duct of the pump. A compensating ring is mounted in the first chamber and inserted on the shaft of the driving wheel to compensate the axial forces of the driving wheel and transmit the motion on the shaft of the driving wheel. A piston is mounted in the second chamber in order to stop against one end of the shaft of the driven wheel, in such manner to compensate the axial forces imposed on the toothed driven wheel.

Abstract: A pair of meshed gears is disposed in a hydraulic chamber of a housing. Bushes in the chamber contact both end surfaces of the gears. Edge surfaces of the gears are chamfered at intermediate parts between tooth tips and tooth bottoms, and the inclination of the intermediate parts is larger than those of the tooth tips and bottom, thereby protecting the edges from damage due to contact force as the gears mesh and preventing leakage between the gears and the support members. Accordingly, the gears may be operated quietly, at high output efficiency, and increased reliability for an extended period.

Abstract: The invention relates to a dry-compressing dual-shaft rotary displacement screw spindle pump machine for delivering and compressing gases. The spindle rotor pair therein includes multiple stages, having a primary delivery thread, a secondary delivery thread and a gas outlet collector chamber therebetween. The primary delivery thread head circle diameter decreases in the gas outlet direction, while the foot circle diameter thereof increases correspondingly for an application-specific matching inner “integral” compression ratio. The secondary delivery thread nominal delivery direction is opposite to the primary delivery thread nominal delivery direction. The secondary delivery thread is implemented such that the actual gas flow direction is opposite to the nominal delivery direction thereof, and is always directed away from the gas outlet plenum, having a gas permeation under ambient pressure just as the space in the gearbox.

Abstract: A pair of meshed gears is disposed in a hydraulic chamber of a housing. Bushes in the chamber contact both end surfaces of the gears. Edge surfaces of the gears are chamfered at intermediate parts between tooth tips and tooth bottoms, and the inclination of the intermediate parts is larger than those of the tooth tips and bottom, thereby protecting the edges from damage due to contact force as the gears mesh and preventing leakage between the gears and the support members. Accordingly, the gears may be operated quietly, at high output efficiency, and increased reliability for an extended period.

Abstract: The present invention deals with the analytical definition of a tooth profile for rotors used in gear pumps. The purpose is to obtain a pump characterized by noiseless operation, minimization of vibrations and pressure overoscillations generated in operating conditions at the beginning and end of life, and high specific displacement, in such a way to increase the delivery of the pump in given volume conditions. This profile is characterized by an active profile of the tooth flanks with involute stub-tooth with transverse contact ratio (?t) comprised in the range from 0.4 to 0.45, helical teeth with helical contact ratio (??) comprised in the range from 0.6 to 0.85, circular inactive tooth bottom and top profiles, with center (Of, Ot) and radius (rf, rt) defined by a non-dimensional parameter ? in the range from 1.1 to 1.6.

Abstract: Screw compressor (1) comprising: a male (2) and a female rotor (3) rotating respectively around a first axis (01) and second axis (02) of rotation, said rotors (2;3) showing, in cross section, meshing lobes (4) and valleys (6) and having profiles generated by enveloping a rack profile (p) including a first curve (z1) of the rack profile (p) extending between a first point (H) and a second point (Q) in a Cartesian reference frame (X, Y) and having a convexity in the positive direction of the axis of abscissa (X), said first point (H) lying on the axis of abscissa (X) at a distance from an origin (0) of the Cartesian reference frame (X, Y) equal to an addendum (hi) of the male rotor (2).

Abstract: An improved geared hydraulic apparatus, comprising a pair of meshing gearwheels, mounted to be reciprocally rotatable in a casing between an inlet side and an outlet side for a fluid having, in use, a substantially transverse flow with respect to the axes of rotation of the gearwheels. The meshing gearwheels create, during their reciprocal rotation, progressive meshing configurations between respective co-operating teeth. In at least one of said progressive meshing configurations is defined, in at least one cross-section of the gearwheels, at least one closed area between respective fluid entrapment teeth. The closed area decreases until it is substantially cancelled out at and around at least one other, separate progressive meshing configuration between the aforesaid respective co-operating teeth.

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: Flowmeter with a pair of helical gears using an oval pitch curve as a reference rack tooth profile. The tooth height ratio of the reference rack tooth profile is ?/4. The reference rack tooth profile is an oval pitch curve of two or less leaves. The moving radius of the oval pitch curve is expressed by ?=a/(1?b cos n?), where ? is a moving radius which is a distance between the center of rotation and the oval pitch curve, “a” is a similarity factor, “b” is a degree of flatness, n (n?2) is the number of leaves, and ? is an argument. The tooth height ratio is h=a/(1?b)?g0, where g0 is a distance between poles of the oval pitch curve and pitch line, wherein g0=a cos ?0/(1?b cos n?0). Values for the similarity factor “a”, degree of flatness “b”, and distance g0 are determined so that the tooth height ratio may be ?m/4.

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: An oval gear set for use in a flow meter comprises first and second gears that are identical to each other and that are configured to engage at a fixed center-to-center distance such that the first and second gears mesh at all angular positions. Each gear of the oval gear set comprises a hub and a plurality of gear teeth. The hub comprises an oval body having a major axis and a minor axis extending through a center of the hub, and a root profile wall circumscribing the major and minor axes. The plurality of gear teeth extend from the root profile wall. Each of the gear teeth has a pair of contact surfaces with circular involute curve profiles.

Abstract: A gear pump comprises a casing having an inlet, an interior, and an outlet. An inlet gear is positioned at the inlet and pressurizes fluid received at the inlet. A drive gear is positioned at the outlet of the casing, the drive gear receiving fluid pressurized by the inlet gear to output pressurized fluid at the outlet. A speed-reduction gear is meshed to the drive gear and connected to the at least one inlet gear, the speed-reduction gear having a greater number of teeth than the drive gear to reduce a rotational speed from the drive gear to the inlet gear, such that the inlet gear has a lower speed that the drive gear. An input shaft is coupled to the drive gear and receives a rotational input to actuate the drive gear.

Abstract: A screw pump includes a casing including a main accommodating bore and plural sub accommodating bores, a main rotor adapted to be rotatably accommodated in the main accommodating bore, and plural sub rotors adapted to be respectively rotatably accommodated in the sub accommodating bores. Each sub rotor is adapted to engage the main rotor. A cross sectional shape of a flank surface of the main rotor, which is taken in a direction perpendicular to an axial direction of the main rotor, is formed along an epitrochoid traced by an edge of the sub rotor not to include an undercut shape. Further, a cross sectional shape of a flank surface of each sub rotor, which is taken in a direction perpendicular to an axial direction of the sub rotor, is formed along an epitrochoid traced by an edge of the main rotor not to include an undercut shape.

Abstract: A rotor profile for a screw compressor includes a male rotor and a female rotor, which are operated in an operation space while being engaged with each other, wherein a rotor profile of the female rotor includes a curve having an operation contact point located around a pitch circle at a following-side of the female rotor, the operation contact point being contacted with the male rotor to operate the male rotor when the female rotor is operated, and the curve is configured with a quadratic function y=Lx2+Mx+N. Here, the constants L, M and N are values determined such that a slip ratio at the operation contact point is minimized. This rotor profile for a screw compressor minimizes a slip ratio at the operation contact point, thereby decreasing abrasion and reducing noise of the compressor.

Abstract: A screw expander in which a pair of male and female screw rotors engaged with each other are housed in a rotor chamber formed in a casing, an expansion force of a high-pressure gas supplied from an intake flow path to the rotor chamber is converted into a rotational force by the screw rotors and the expanded low-pressure gas is exhausted to an exhaust flow path includes a valve mechanism capable of allowing communication between an intermediate pressure portion, which is a space in the rotor chamber and can be separated from the intake flow path and the exhaust flow path by the screw rotors, and a bypass flow path, to which a high-pressure gas is supplied, and a controller for controlling the valve mechanism in accordance with an operation expansion ratio which is a ratio of a pressure in the intake flow path to a pressure in the exhaust flow path.

Abstract: A pump comprises a driving rotor and a driven rotor that are positioned in a housing such that, as the driving rotor and the driven rotor rotate, the teeth of the driving rotor and the teeth of the driven rotor mesh to form a positive displacement seal. The teeth of the driving rotor and the driven rotor are configured such that seals between the inlet side and the discharge side of the pump are formed between only the leading surfaces of the teeth of the driving rotor and the trailing surfaces of the teeth of the driven rotor.

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: A low noise gear set for use generally and preferably with a power plant having an engine driving a pump connected to a low pressure fluid source, generating high pressure fluid at an output. The idle gear meshes with the drive gear along two points of the profile of the corresponding gears. The first point being the root of one gear tooth meshing with the tip of the opposite gear tooth creating an initial first contact point and a subsequent second point along the profile when the teeth are disengaging at the first point and engaging at the second point, forming a sealed area, allowing the fluid to hydrostatically escape between the points.

Abstract: Screw compressor (1) comprising: a male (2) and a female rotor (3) rotating respectively around a first axis (01) and second axis (02) of rotation, said rotors (2;3) showing, in cross section, meshing lobes (4) and valleys (6) and having profiles generated by enveloping a rack profile (p) including a first curve (z1) of the rack profile (p) extending between a first point (H) and a second point (Q) in a Cartesian reference frame (X, Y) and having a convexity in the positive direction of the axis of abscissa (X), said first point (H) lying on the axis of abscissa (X) at a distance from an origin (0) of the Cartesian reference frame (X, Y) equal to an addendum (hi) of the male rotor (2).

Abstract: A multi-rotor compressor and method of manufacturing is provided. The compressor includes a housing with a plurality of identical planet rotors. The planet rotors are equally spaced apart at a fixed distance from a centerline. A single sun rotor is provided that is disposed to cooperate with the plurality of identical planet rotors in the compression of gas. The number and radial spacing of the plurality of identical planet rotors about said single sun rotor may be arranged in different configurations to change an output capacity parameter for said compressor.

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).

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 screw compressor rotatably accommodates, within a casing including a suction port and a delivery port, a pair of female and male rotors under the meshed state and compresses gas in the state where a liquid is mixed by pouring the liquid to the gas confined within a working chamber formed with both rotors and the casing. On the wall surface of the casing opposing to the rotor delivery end, a recessed part is provided. The working chamber is communicated with the recessed part immediately before isolating from the delivery port and this communication is maintained until a volume of the working chamber substantially becomes zero. Thereby, the screw compressor can be control increase in power consumption, vibration, and noise.

Abstract: An ideal positive displacement flowmeter which has a pair of helical gears given by using oval pitch curve as reference rack tooth profile, with the tooth height ratio of the reference rack tooth profile even with a small number of teeth being set to ? m/4 which is a logical limit for the tooth height ratio of a one-point continuous contact tooth profile and which has no confinement phenomenon between tooth profiles. The positive displacement flowmeter has a pair of helical gears (1, 2) in a casing (3). The reference rack tooth profile of the pair of helical gears (1, 2) is an oval pitch curve of two or less leaves. The moving radius of the oval pitch curve is expressed by ?=a/(1?b cos n?), where ? is a moving radius which is a distance between the center of rotation and the oval pitch curve, “a” is a similarity factor, “b” is a degree of flatness, n (n?2) is the number of leaves, and ? is an argument.

Abstract: A screw pump (10) comprises a stator (12) having a fluid inlet (18) and a fluid outlet (20), the stator housing first and second externally threaded, tapered rotors (26, 28) mounted on respective shafts and adapted for counter-rotation within the stator (12) to compress fluid passing from the fluid inlet to the fluid outlet, wherein the threads (30, 32) have a pitch that increases towards the fluid outlet (20).

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: A cross section of a tooth profile of a first screw rotor (17) perpendicular to the rotor axis includes a tooth top arc (A1B1), a tooth bottom arc (C1D1), a first curve (A1C1), and a second curve (B1D1). The first curve (A1C1) is a first trochoidal curve that connects a first end (A1) of the tooth top arc (A1B1) to a second end (C1) of the tooth bottom arc (C1D1). The second curve (B1D1) connects the second end (B1) of the tooth top arc (A1B1) to the first end (D1) of the tooth bottom arc (C1D1). The second curve (B1D1) is a composite curve formed by an involute curve (B1E1) and a second trochoidal curve (E1D1), which extend continuously from each other at a first intersection point (E1). A screw pump (11) thus suppresses leakage of fluid with improved performance.

Abstract: There is disclosed a Roots type pump in which two rotors are rotated synchronously in a pump chamber to compress fluid therein, wherein respective stop positions of the rotors in the pump chamber at a time of stopping the pump are determined independently of each other.

Abstract: An intake assembly, such as a supercharger assembly, is provided for an internal combustion engine. The intake assembly includes a housing having a wall defining an inlet passage through which intake air enters the intake assembly. A plurality of stiffening ribs is provided on the wall opposite the inlet passage and at least partially defines at least one cavity. A plate is mounted to the wall of the housing and further defines the at least one cavity. The wall defines at least one orifice configured to provide communication between the inlet passage and the at least one cavity. The at least one cavity and the at least one orifice cooperate to form at least one resonator. A method of forming the intake assembly having integral resonators is also provided.

Abstract: A cross section of a tooth profile of a first screw rotor (17) perpendicular to the rotor axis includes a tooth top arc (A1B1), a tooth bottom arc (C1D1), a first curve (A1C1), and a second curve (B1D1). The first curve (A1C1) is a first trochoidal curve that connects a first end (A1) of the tooth top arc (A1B1) to a second end (C1) of the tooth bottom arc (C1D1). The second curve (B1D1) connects the second end (B1) of the tooth top arc (A1B1) to the first end (D1) of the tooth bottom arc (C1D1). The second curve (B1D1) is a composite curve formed by an involute curve (B1E1) and a second trochoidal curve (E1D1), which extend continuously from each other at a first intersection point (E1). A screw pump (11) thus suppresses leakage of fluid with improved performance.

Abstract: On screw compressors for extremely high discharge pressures, e.g. for application in refrigeration systems operating with CO2 in a transcritical process, featuring two rotors, a male rotor and a female rotor having a ratio of male-to-female rotor lobes of 4:6, 5:6 or 5:7, with the male rotor having a drive-shaft end, and both rotors are enclosed in a housing, the wrap angle of the profile section of the male rotor is less than 1.5 the lobe-pitch angle, and the working cycle from the beginning of suction till the end of discharge is less than 600° of the angle of rotation of the male rotor, and the length-to-diameter ratio of the profile section of the male rotor lies between 0.3 and 0.5.