Abstract: A radial turbine impeller is provided, comprising a circular main disk provided with a plurality of blades, each having a negative pressure surface and a positive pressure surface; scallops being formed by cutting off the main disk between the negative pressure surface of the one blade and the positive pressure surface of the other blade adjacent to the one blade, respectively; wherein a minimum radius portion of the scallop having a minimum distance between a center of the circular main disk and the edge of the scallop is positioned closer to the positive pressure surface so that the scallop is asymmetric between the negative pressure surface of the one blade and the positive pressure surface of the other blade adjacent thereto. It is possible to prevent the turbine efficiency from lowering due to the impingement of a fluid onto the edge of the scallop.

Abstract: A friction vacuum pump for use in a system for regulating the pressure in a vacuum chamber includes a multistage turbomolecular vacuum pump section (6) whose stages each consist of a row of stator vanes and rotor vanes (14 or 13). The pump regulates the pressure of heavy gases or of a gas mixture containing heavy gases. To this end, the friction vacuum pump (1) is equipped with a molecular pump section (11) located on the fore-vacuum side and a space (21, 22, 23), in which the pump action is interrupted. The space is provided in the transition area from the turbomolecular vacuum pump section (6) to the molecular pump section (11) or in the transition area from the molecular flow to viscous flow.

Abstract: The invention relates to a friction vacuum pump (1) comprising a fixed element (7) bearing rows of stator blades and a rotating element (6) bearing rows of rotor blades. The rows of stator blades and rotor blades are arranged concentrically with respect to the axis of rotation (4) of the rotating element (6) and engage with each other. In order to create a short friction pump, the elements (6, 7) bearing the rows of rotor blades and stator blades extend in a substantially radial manner and the longitudinal axes of the blades (2, 3) extend in a substantially axial manner. A friction vacuum pump (1) comprises a fixed element (7) bearing rows of stator blades (3) and a rotating element (6) bearing rows of rotor blades (2). The rows of stator blades and rotor blades are arranged concentrically with respect to an axis of rotation (4) of the rotating element (6) and mesh with each other.

Abstract: A rotor assembly for a gas turbine engine, having a rotor member with axially spaced-apart front and rear end portions. A thermal shield is located axially downstream of the rear end portion of the rotor for thermally shielding the same from the hot surrounding environment. The thermal shield includes a rear coverplate and an axial gap between the rear coverplate and the rear end portion of the rotor member.

Abstract: To provide a small vacuum pump making it possible to efficiently perform evacuation from the atmosphere to a high vacuum (degree of vacuum: 10−5 Pa) by using a single pump unit. A turbo-molecular pump mechanism portion is arranged on the high-vacuum side, a volute pump mechanism portion is arranged on the atmosphere side, and a thread groove pump mechanism portion is arranged between the turbo-molecular pump mechanism portion and the volute pump mechanism portion. Further, rotor blades of the turbo-molecular pump mechanism portion, a rotor of the thread groove pump mechanism portion, and an impeller of the volute pump mechanism portion are integrally mounted to a single rotor shaft, which is rotated by a single motor.

Abstract: A turbomolecular vacuum pump (5) comprises a first pumping section (1) having pumping stages with bladed rotor discs, a second pumping section (2) having pumping stages with smooth rotor discs, a third pumping section (3) having a pumping stage with a toothed rotor disc (26), and a fourth pumping section (4) of the ejector or venturi pump type. (FIG.

Abstract: A gas friction pump including a housing (1) having a suction opening (2) and a gas outlet opening (3), rotor (12) and stator (14) components arranged in the housing (1) for delivery of gases and for obtaining a pressure ratio; and an additional, at least one-stage, concave pump unit (20, 30, 40) provided at a side of the suction opening (2) and having a gas delivery structure, with the additional pump unit (20, 30, 40) being so formed that gas delivery takes place in a radial direction, and with rotor components (21, 31, 41) of the additional pump unit (20, 30, 40) being supported on the same rotor shaft (4) as the rotor components of the pump itself.

Abstract: In a centrifugal blower unit for an inside and outside air double-layer flow type vehicular air conditioner, a centrifugal fan includes a first fan and a second fan. The first fan and the second fan have plural first blades and second blades arranged about a rotation axis, respectively. A separation wall is provided between the first blades and the second blades. The separation wall restricts mixture of air blown by the first fan and air blown by the second fan. Also, it restricts the air blown by the first fan striking against an end of a divider, thereby suppressing noise due to turbulent air flow.

Abstract: A compound vacuum pump includes a regenerative section and a Holweck section. An annular abutment is formed on the radially innermost rotating cylinder of the Holweck section. The abutment acts to cause dust and foreign particles entering an inlet of the pump to be trapped before entering an inlet of the regenerative section. A circular barrier may be used with the abutment to assist with trapping the dust and foreign particles.

Abstract: A vacuum pump adopts a positioning structure in which stator blades and spacers are arranged in the radial direction of a pump case by the contact between the outer peripheries portion of the stator blades and the inner periphery portion of the pump case and the contact between the outer periphery portions of the spacers and the inner periphery portion of the pump case. Accordingly, the spacer interposed between the upper and lower stator blades can have a simplified shape that serves a function of only setting the spacing between the stator blades to a prescribed length, thus decreasing the number of steps and costs of processing the spacer, and accordingly reducing the costs of the entire vacuum pump.

Abstract: A molecular vacuum pump (1) includes a stator unit (9) which has a stator blade package including one or more rows of stator blades (42), and a rotor unit (8) which has rotor blade package including one or more rows of rotor blades (41). The rotor blades (41) and the state blade (42) intermesh with each other in the functionally assembly state. The rotor blades 941) include slots (61) whose arrangement, depth and width are selected such that the stator unit (9) and the rotor unit (8) may be screwed together or unscrewed from one another. Alternatively, the stator blades (42) include slots (61) whose arrangement, depth and width are selected such that the stator unit (9) and the rotor unit (8) may be screwed together or unscrewed from one another.

Abstract: An impeller suitable for use in a centrifugal pump, the pump including a pump chamber and a pump inlet. The impeller includes a main body portion which includes a plurality of primary pumping blades or vanes and one or more flow inducing blades or vanes which project from the main body portion of the impeller and when installed into the pump inlet.

Abstract: A vacuum pump includes a housing having an inlet port and an exhaust port, a plurality of vacuum pumping stages located within the housing and disposed between the inlet port and the exhaust port, and a motor. The vacuum pumping stages include gas drag stages, each including a stator and an impeller. The impellers of successive ones of the gas drag stages are configured for efficient operation at progressively higher pressures. The impellers of the gas drag stages may have pumping surfaces with a surface topography for efficient operation at progressively higher pressures. The motor rotates the impellers such that gas is pumped from the inlet port to the exhaust port.

Abstract: A turbo-molecular pump includes a casing having an intake port, a stator fixedly mounted in the casing, and a rotor supported in the casing for rotation relatively to the stator. The stator and the rotor make up a turbine blade pumping section and a groove pumping section for evacuating gas. A scattering prevention member is provided for preventing fragments of the rotor from being scattered through the intake port.

Abstract: A method and apparatus is disclosed for pumping a material, especially thick, gas-containing, fiber suspensions for wood processing. The apparatus includes a centrifugal pump with a rotor having blades twisted such that the pitch of the blade changes along the length of the rotor.

Abstract: A technique for facilitating the movement of multi-phase fluids. The technique utilizes a compressor pump and a production pump. The compressor pump compresses a fluid to remove vapor phase and then discharges the pressurized fluid to a production pump. The production pump produces the pressurized fluid to a desired location with greater efficiency due to reduction of the vapor phase.

Abstract: A gas friction pump including a plurality of pumping active rotor and stator components arranged in the pump housing for delivery of gases and for producing a compression ration and having a diameter larger than a diameter of the suction opening formed in the housing, and a modified rotor component located adjacent to the suction opening and having a radial extent which increases starting from the suction opening in a direction of a radial extent of the pumping active rotor and stator components.

Abstract: In a vacuum processing apparatus comprising a reactor and a vacuum pump connected to the reactor to draw up a gas held in the reactor, the vacuum pump comprising a diffusion pump and an auxiliary pump, the diffusion pump and the auxiliary pump are connected through an exhaust line and a cooling unit is provided in the exhaust line, whereby the gas is cooled by the cooling unit to liquefy or condense an oil smoke comprised of a diffusion pump oil contained in the gas, to cause the resultant oil to deposit in the exhaust the diffusion pump oil can be prevented from flowing into the auxiliary pump even when material gases fed in at a high rate are exhausted.

Abstract: A gas friction pump including a housing having a suction opening and an exhaust opening, main rotor and stator components arranged in the housing and cooperating with each other for delivering gases and for producing a pressure difference, and an auxiliary pumping unit provided at a side of the suction opening and having a gas delivery structure that provides for gas delivery in a radial direction, with the auxiliary pumping unit being formed of at least one stage and having auxiliary rotor and stator components, with the auxiliary rotor components being supported on the shaft which supports the main rotor components.

Abstract: A multiple-type pump has a simple construction and superior durability. The multiple-type pump has the capacity to perform air evacuation at high velocities in the atomospheric pressure zone to high vacuum zone range. The multiple-type pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.

Abstract: In an exemplary embodiment, a motor assembly includes a shaft and a compound fan assembly that provides axial and centrifugal air flow. The fan assembly includes a body including an outer surface, a cavity defined by the body outer surface, a plurality of first blades extending radially outwardly from the body outer surface, and a plurality of second blades disposed within the cavity. The shaft is concentric with the body and the second blades are rotatably coupled to the shaft.

Abstract: A technique for facilitating the movement of multi-phase fluids. The technique utilizes a compressor pump and a production pump. The compressor pump compresses a fluid to remove vapor phase and then discharges the pressurized fluid to a production pump. The production pump produces the pressurized fluid to a desired location with greater efficiency due to reduction of the vapor phase.

Abstract: A two stage compressor for a gas turbine engine with a mixed flow first stage, a centrifugal second stage, and an intermediate duct. The mixed flow stage has a mixed rotor rotatable about the central compressor axis with a circumferential array of mixed flow blades between the mixed flow hub and an associated mixed flow shroud. The downstream centrifugal stage has a centrifugal rotor rotatable about the same compressor axis. The centrifugal rotor has a circumferential array of radially extending centrifugal flow blades between the centrifugal flow hub and an associated centrifugal flow shroud. An intermediate duct has an inner duct wall defining an axially curvilinear transition surface of revolution between an outlet end of the mixed flow hub and an inlet end of the centrifugal flow hub and an outer duct wall defining an axially curvilinear transition surface of revolution between an outlet end of the mixed flow shroud and an inlet end of the centrifugal flow shroud.

Abstract: A cell for pumping a multiphase effluent includes two rotary parts (4-5), the first one (4) having a hydraulic wheel designed for transmitting kinetic energy to each of the multiphase effluent phases entering cell (1a-1b), and the second one (5), following the first, being an energy converting device designed for homogenizing the phases, transferring kinetic energy between the phases, entraining the lightest phase, converting kinetic energy into pressure and compressing the homogeneous effluent before it leaves the cell. All of the rotary parts of the cell are mounted on a common shaft (3) axially arranged inside a fixed housing (2) having an inlet and an outlet for the multiphase effluent.

Abstract: A vacuum pump, including a housing having inlet and outlet; a shaft arranged in the housing and supported bearing provided in the housing, drive for rotating the shaft; and a plurality of pumping units arranged in the housing and formed each of rotational and stationary gas delivery components with the rotational components being supported on the shaft and the stationary components being connected with the housing, at least one of the pumping units consisting of a plurality of connected parallel to each other and arranged one after another in an axial direction, molecular pumping stages with each pumping stage being formed based on Gaede principle; with the molecular pumping stages being connected with each other in common connection channels.

Abstract: A molecular drag vacuum pump configured for pumping a gas stream from an inlet to an outlet, the pump including a high-speed spinning disk having a channel formed in its edge, disposed within a housing. A passageway is formed on the inside of the housing adjacent the disk, and gas comes in contact with surfaces of the spinning disk in successive stages, conformable wipers being disposed adjacent the spinning disk to direct the gas stream to the successive stages. The disk can be powered by an integral motor, comprising permanent magnets associated with the disk and cooperating coils associated with the housing.

Abstract: Apparatus is disclosed for pumping a pulp suspension including a housing and an impeller including a central hub, a wheel disk surrounding the central hub, and pump blades extending radially from the central hub along the wheel disk, which includes at least one opening for discharge of an entrained gas from the pump suspension, a vacuum pump at the rear face of the impeller, and vacuum pump blades mounted for rotation within the vacuum pump housing, which includes an outer wall which is eccentrically disposed with respect to the vacuum pump blade, and a rear wall which includes a suction port for receiving the entrained gas, and with the vacuum pump housing mounted adjacent to the central hub to provide a gap therebetween, so that vacuum pump housing is axially adjustable so that the gap can be altered by axial adjustment of the vacuum pump housing.

Abstract: An apparatus for mounting a plurality of rotary compressors with minimal mechanical tolerances, wherein each of the compressors imparts axial forces on the structures with which they are mounted. The mounting apparatus includes an articulated shaft that rotationally couples and axially decouples the impeller wheels of the rotary compressors. The articulated shaft interoperates with compressors configured in a back-to-back configuration and, in addition, may be coupled to a motor. The articulated shaft and the impeller wheels may be supported by air bearings. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A multiple-type pump has a simple construction and superior durability. The multiple-type pump has the capacity to perform air evacuation at high velocities in the atomospheric pressure zone to high vacuum zone range. The multiple-type pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.

Abstract: A centrifugal pump for a gas turbine engine, including a housing having a fluid inlet port for receiving fluid at an initial pressure and an interior chamber defining a central axis. An impeller disk disposed within the interior chamber of the housing and mounted for rotation about the central axis. The impeller disk defines first and second inlet areas and has a plurality of circumferentially spaced apart channels formed therein which extend from the inlet areas for conducting fluid from the inlet areas in a radially outward direction upon rotation of the impeller disk so as to increase the pressure of the fluid. A first collector is formed by the housing for receiving the fluid from the first inlet area via the channels at a first elevated pressure relative to the initial pressure and a second collector is formed by the housing for receiving fluid from the second inlet area via the channels at a second elevated pressure relative to the first elevated pressure.

Abstract: A compound vacuum pump includes a regenerative section and a Holweck section. An annular abutment is formed on the radially innermost rotating cylinder of the Holweck section. The abutment acts to cause dust and foreign particles entering an inlet of the pump to be trapped before entering an inlet of the regenerative section. A circular barrier may be used with the abutment to assist with trapping the dust and foreign particles.

Abstract: A multiple-type vacuum pump has a simple construction and superior durability. The multiple-type vacuum pump has the capacity to perform air evacuation at high velocities in the low to high vacuum zone range. The multiple-type vacuum pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.

Abstract: A gas friction pump including a housing having a suction opening and an exhaust opening, main rotor and stator components arranged in the housing and cooperating with each other for delivering gases and for producing a pressure difference, and an auxiliary pumping unit provided at a side of the suction opening and having a gas delivery structure that provides for gas delivery in a radial direction, with the auxiliary pumping unit being formed of at least one stage and having auxiliary rotor and stator components, with the auxiliary rotor components being supported on the shaft which supports the main rotor components.

Abstract: A flow directing device, system and method for delivery and pumping medium to high consistency stock slurries eliminates bridging of stock, creates a non-vortexing improved flow into the pump suction of a pump, is independent from pump operation, minimizes “slip/stick”, and does not mix air into the pulp fibers. The flow directing device is a low-speed, mechanical device including a two-stage turbine, a turbine shaft, a turbine mounting adapter, a gear reducer and an electric motor. The device is used with a dropleg to assist flow of medium to high consistency suspensions (pulp) to the pump, preferably a rotary pump. The flow directing device is operated independently from the pump. The flow directing device and pump work in concert with each other to form a stock pumping system capable of handling paper stock consistencies from 8-18% without the problems associated with other types of pumping systems.

Abstract: A high-vacuum pump includes a first vacuum pump section and a second vacuum pump section coupled in series and having an interstage region between them. The vacuum pump further includes a housing containing the first and second vacuum pump sections. The housing includes a high conductance peripheral duct surrounding all or part of the interstage region and coupled to the interstage region. The housing defines a first inlet port coupled to an inlet of the first vacuum pump section, a second inlet port coupled to the peripheral duct, and an exhaust port coupled to an outlet of the second vacuum pump section. Examples of high-vacuum pumps according to the invention include turbomolecular vacuum pumps, diffusion pumps and mixed vacuum pumps which include both axial flow stages and molecular drag stages.

Abstract: A turbine comprising a first housing having a first shaft rotatably drivingly connected to a second shaft and mounted in the first housing; a plurality of first spaced apart discs mounted on the first shaft and rotatable therewith; a second housing having the second shaft rotatably mounted in the second housing; and, a plurality of second spaced apart discs mounted on the second shaft and rotatable therewith.

Abstract: The present invention relates to a friction vacuum pump having at least one turbomolecular pump stage (2) joined at its pressure side to a screw pump stage (4). In order to improve the pump properties it is proposed that a filling stage (3) be arranged between the turbomolecular pump stage (2) and the screw pump stage (4) that has blades (13) whose length corresponds at the suction side to the active length of the blades at the pressure side of the turbomolecular pump stage (2), and at the pressure side to the depth of the suction-side region of the screw (14) of the screw stage (4).

Abstract: The invention provides a self-priming centrifugal pump capable of sucking up and pumping a highly viscous liquid containing muddy substances including a large amount of bubbles, and solid foreign matters, of preventing the flow of the liquid from the side of a main pump unit into a vacuum device and from the vacuum device into the main pump unit at all stages of operation including starting, operating and stopping stages and of perfectly automatic operation, and very economical in costs of equipment and maintenance.The self-priming centrifugal pump has a main pump unit for pumping a liquid, an auxiliary pump unit for centrifugal gas-liquid separation, and an exhaust vacuum device.

Abstract: A vacuum pump comprising at least a molecular drag section and a turbo-molecular section, a rotor common to both sections and a stator common to both sections. The turbo-molecular section is positioned wholly within an envelope defined by the molecular drag section.

Abstract: A centrifugal and vacuum pump combination in which the impeller of a centrifugal pump is disposed on the same shaft as a rotor of the vacuum pump, with a gas outlet extending between the centrifugal and vacuum pumps, is operated by positively controlling the flow of gas passing through the gas outlet duct, for example by changing the effective cross-sectional flow area of the outlet duct. The fluent material handled by the pump is preferably a cellulose fiber slurry having a solids consistency of between about 6-15%. The control can be effected automatically in response to solids consistency, inlet pressure, and/or gas content of the slurry being pump. The vacuum pump housing includes an eccentric inner wall, and operation of the pump may be primarily controlled by moving the vacuum pump housing.

Abstract: A vacuum pump comprising a plurality of vacuum stages and having a first pump inlet through which gas can pass through all the pump stages and a second inlet through which gas can enter the pump at an interstage location and pass only through subsequent stages of the pump, wherein the pump stages prior to the interstage are sized differently to these stages subsequent to the interstages such that the pump overall suits the pressure requirements and pumping capacity of the different systems attached to the first and second inlet, respectively.

Abstract: A harden screw form and methods of making same for use with, for example, positive displacement rotary axial screw pumps are disclosed. The methods include the use of a CNC machine with a laser and a special, newly developed optic for selectively hardening the contact areas of screw forms, such as for example, rotors used in positive displacement rotary axial screw pumps such that the rotor undergoes only controllable or predictable distortion as a result of the hardening process. Hardened screw forms manufactured by the CNC/laser/optic process that are free of uncontrollable or unpredictable distortion are also disclosed.

Abstract: A turbomachinery includes an attachment structure of an impeller to a rotational shaft which does not incur looseness even when it is subjected to temperature cycles, and which can be obtained without increasing manufacturing costs. The rotational shaft has the impeller at an end portion thereof. A cylindrical member is provided concentrically of the rotational shaft at the end portion for holding the impeller. The impeller is fitted inside the cylindrical member by shrink fitting.

Abstract: A high temperature pump is compact in size, reasonable in manufacturing cost and capable of stable pumping operation. The high-temperature motor pump includes a pump portion for pumping a liquid, a motor portion integrated with the pump portion for driving the same, and a rotatable shaft for transmitting rotation of the motor portion to the pump portion. A magnetic bearing is provided within the motor portion for supporting one end of the rotatable shaft by actively controlling a position thereof in a radial direction. A hydrostatic bearing is provided within the pump portion for supporting the other end of the rotational shaft in a radial direction by using a hydrostatic pressure of a portion of the liquid pumped by the pump portion.

Abstract: A centrifugal and vacuum pump combination in which the impeller of a centrifugal pump is disposed on the same shaft as a rotor of the vacuum pump, with a gas outlet extending between the centrifugal and vacuum pumps, is operated by positively controlling the flow of gas passing through the gas outlet duct, for example by changing the effective cross-sectional flow area of the outlet duct. The fluent material handled by the pump is preferably a cellulose fiber slurry having a solids consistency of between about 6-15%. The control can be effected automatically in response to solids consistency, inlet pressure, and/or gas content of the slurry being pump. The vacuum pump housing includes an eccentric inner wall, and operation of the pump may be primarily controlled by moving the vacuum pump housing.

Abstract: A pump body 10 of a drainage pump 1A comprises a pump chamber 12, inlet 15, and outlet 17. A rotary vane 300 mounted in the pump body 10 is coupled to a motor mounted above the pump body 10, and comprises a shaft 310 and four large-radial blades 320. Formed below the large-radial blades 320 are small-radial blades 350 to make a liquid at the inlet rise. Lower edges of the large-radial blades 320 are connected together by a disk 350 having an opening at the center and interceptively dividing the surface of the liquid rising from the inlet. Thus the amount of the liquid in contact with the large-radial blades 320 above the disk 350 decreases, and the load to the rotary vane decreases. At the same time, bubbles, noise and vibrations caused by bubbles also decrease. By surrounding the outer circumference of the large-radial blades 320 with a ring member, return water W5 moving back from the outlet 17 when the pump stops is damped by the wall member 360 and returns smoothly to the inlet 15.

Abstract: An impeller is for separating a conveyed stream of material. The impeller has a central rotatable hub with a plurality of blades extending radially therefrom. The hub and blades form a number of generally wedge-shaped material receiving spaces within the impeller. One set of spaces has a baffle arrangement which is configured to direct material in this set outwardly from the impeller on the upstream side of the baffle arrangement. Another set of spaces has a guide arrangement which is configured to guide the material in this set of spaces outwardly from the impeller on the downstream side of the baffle arrangement. The impeller is particularly useful for separating streams of particulates, such as wood chips, compressed shavings, or the like.

Abstract: The invention is directed to a flow energizing system for turbomachinery including means for forming a plurality of rotating jet-sheet blades upstream of an impeller and a component for circumferentially varying the blade geometries of the plurality of rotating jet-sheet blades. The a component for forming a plurality of rotating jet-sheet blades includes: impeller shroud 26 having upstream-projecting axial extension 28 attached coaxially with and projecting upstream of shroud 26; recirculation chamber 30 surrounding shroud and axial extension, 26 and 28; recirculation flow inlet 32 formed by a gap between housing 12 and downstream ends, 20a and 26a, respectively, of impeller 20 and shroud 26, for allowing backflow to pressurize recirculation chamber 30; and a plurality of generally axially-extending jet-sheet slots 34 circumferentially distributed around a periphery of axial extension 28 and passing therethrough.

Abstract: A molecular drag compressor includes a rotor disk and a stator that defines a tangential flow channel having an inlet and an outlet. A stationary baffle is disposed in the tangential flow channel adjacent to the outlet. The baffle is spaced from the rotor disk by a gap. A surface of the baffle facing the rotor disk has surface irregularities including peaks for defining the gap and valleys between the peaks for accumulation of particles. The surface irregularities may form a series of grooves. The molecular drag compressor is preferably utilized in a high vacuum pump which includes an axial turbomolecular compressor and a molecular drag compressor. Additional features which limit the effect of particulate accumulation in molecular drag compressors are disclosed.

Abstract: A friction vacuum pump (1) is provided with pump sections of different designs, of which the pump section on the inlet side consists of turbomolecular pump stages (14, 15) and a further pump section of Siegbahn stages (16, 17) with spiral grooves (19), whereby the active pumping surfaces of the Siegbahn stages are formed by facing surfaces of an annular rotor disc and an annular stator disc (16, 17). To simplify the production of such a pump, it is proposed that the annular stator discs (16) have spiral grooves (19).