US3265293A - Vacuum pump of the screw rotor type and method for operating the same - Google Patents

Vacuum pump of the screw rotor type and method for operating the same Download PDF

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Publication number
US3265293A
US3265293A US519630A US51963066A US3265293A US 3265293 A US3265293 A US 3265293A US 519630 A US519630 A US 519630A US 51963066 A US51963066 A US 51963066A US 3265293 A US3265293 A US 3265293A
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pressure
stage
compression
compressor
vacuum pump
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Schibbye Lauritz Benedictus
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Svenska Rotor Maskiner AB
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Svenska Rotor Maskiner AB
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
    • F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
    • F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
    • F04C27/008—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids for other than working fluid, i.e. the sealing arrangements are not between working chambers of the machine
    • F04C27/009—Shaft sealings specially adapted for pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • F04C29/0007—Injection of a fluid in the working chamber for sealing, cooling and lubricating

Definitions

  • the present invention relates to vacuum pumps and more particularly to vacuum pumps of the screw rotor type, and has for its general objects the provisions of novel and improved methods and apparatus for the creation and maintenance of sub-atmospheric pressures in pressure vessels or systems requiring such pressures, such, for example but without limitation, as condensers utilized in steam turbine power plants and reaction vessels of various kinds utilized in chemical processes involving steps required to be effected at sub-atmospheric pressures.
  • the eld with which the invention is particularly concerned and to which it is primarily directed is that in which the vacuums are within the range practically feasible of attainment with reciprocating mechanical vacuum pumps even though the invention has -a wider range extending down to vacuums corresponding to somewhat lower absolute pressures.
  • the lower limit of the range of the reciprocating pumps is represented by vacuums corresponding to absolute pressures of some 71/2 to 10 millimeters of mercury (see Marks Mechanical Engineers Handbook, Fifth edition, 1951, page 1890), which values -are representative of absolute pressures substantially lower than those required for the majority of commercial installations such, for exlaimple, as steam condensers for turbine plants and the like, the most emcient operating pressures for which may be of the order of one or more inches of mercury (see Marks Handbook noted above, page 1173, giving a table of such values for the most economical vacuum vfor the majority of installations).
  • vacuum pumps of relatively large capacity are required ⁇ for the evacuation of the relatively large vessels required, in order to bring the pressures down to the desired level, and this large capacity must be coupled with relatively high efficiency of operation over long periods lat the normal subatmospheric operating pressure when the actual mass of fluid being evacuated is relatively very small.
  • compressors of the helical screw rotor type more commonly known as screw compressors, would be highly useful as vacuum pumps for producing and maintaining vacuums within the range under consideration, but for reasons hereinafter more fully appearing, it was found that such compressors in their most simple and economical form, that is, single stage compressors, or when designed in the form of conventional two-stage compressors, would not economically be feasible or satisfactory.
  • the known conventional form of this apparatus comprises a housing structure, enclosing two intermeshing rotors having helical lands and grooves forming between themselves and the housing structure chevron-shaped compression chambers decreasing in volume between the time of cut-off from an inlet port in the housing to the time of communication with a delivery port in the housing spaced from the inlet port.
  • volumetric eciency of the machine is dependent upon the extent of the pressure rise in the compression chambers during any one cycle, or in other words, the value of the compression ratio, since the leakage from the apositively sea-led compression chambers will obviously increase with increase in the pressure rise in a single stage.
  • the present invention provides ⁇ a very simple and effective solution to this situation by providing a new and improved form of two-stage compressor of the screw rotor type, which effectively overcomes the deficiencies of the single-stage type and which enables such Ia reduction in the size of the compressor to be effected, in relation to the size of a single-stage compressor of the same capacity, that the cost of a two-stage compressor of a given size may be not greater and can be even less than lthat of a single-stage compressor having the capacity for the same duty.
  • the total pressure rise required to deliver against atmospheric pressure from a desired inlet pressure is divided into two stages, the second stage of which may ⁇ be termed the main compression stage, since this stage will operate through much the higher compression ratio, and which m-ain stage is preceded by what may be termed a pre-compression stage, having a relatively very low compression ratio, and consequently, a relatively very high volumetric eiciency, and delivering the pre-compressed fluid at a relatively very low intermediate pressure to the second compression stage.
  • the compression ratio for the initial or pre-compression stage should not eX- ceed to 1 and preferably should be as low as of the order of 2 or 3 to 1.
  • the swept Volume of the main stage of such a two-stage compressor will thus as the volume of the working uid in the inlet of the main stage will be only about half that of the precompression stage, if for the sake of simplicity the temperature rise due to compression is disregarded, be about through the compressor is assumed to be constant the intermediate pressure between the two stages increases so that the pressure ratio of the preacompression stage increases from 2 to 1 to 2.2 to 1 resulting in a decrease of the volumetric eiciency of the pre-compression stage from to 94.5%.
  • the net variation of 'the volumetric efciency in the pre-compression stage due to 10% manufacturing variation in clearance will thus be only about 1%.
  • the capacity of the two-stage compressor will thus vary with only 1% compared with the 40% variation of the corresponding single-stage compressor.
  • the rotor length of the main stage will be only about 40% of the designed length of the single stage rotor length so that the total rotor length of the pre-compression ⁇ and main stages including intermediate shaft portions will not exceed the rotor length of the single-stage compressor at the same time as the rotor diameter of the two-stage compressor will be only about 40% of that of the single-stage compressor.
  • the overall dimensions of the two-stage compressor will thus be considerably smaller than those of ithe single-stage compressor and consequently the costs of the two-stage compressor will be lower than those of the single-stage compressor.
  • the pre-compression stage can be considered as a highly efficient non-return valve delivering a much reduced volume of evacuated fluid to the main compression stage for subsequent compression through a much higher compression ratio at -rnuch lower efficiency, the latter, however, not being of material significance since the highly efficient pre-compression stage is determinative of the volumetric capacity of the apparatus and consequently the size required for a given duty.
  • the invention further contemplates in its preferred form the use of an apostively sealed pre-compression stage of the screw rotor type and further as a preferred embodiment of that form contemplates the employment of a pre-compression stage, the rotors for which are in tandem with the rotors of the m-ain stage, with the rotors of like -diameter and helix angle for obvious reasons of manufacturing facility and low cost.
  • the displacement or swept volumes of the two stages are proportional to the lengths of the rotors in the respective stages. Since the stages are connected in series, the mass ow through the different stages must ⁇ be eX-actly the same so that to obtain the value of the real volume of the fluid handled, these swept volumes must be corrected by relating them to the volumetric eflciencies of the respective stages.
  • the swept volumes of the two stages may in a comparison therebetween be represented only by the length of the rotor in each stage, LI and LH, spectively.
  • the real volume of the passing fluid has to be determined by correction with regard to the volumetric eiciency of each stage, avon and mom, respectively.
  • the mass of fluid passing each stage will be represented by the product of the real volume of the fluid and the inlet pressure to said stage, the inlet pressure p1 and the intermediate pressure pmt, respectively.
  • the apositive sealin-g characteristic of the screw compressor provides automatic adjustment of the actual compression ratio being effected in the two stages relative to each other and relative to the over-all compression ratio required to effect the necessary pressure rise in order to deliver against a substantially constant delivery pressure from an inlet pressure which may be variable.
  • this ratio V being determined by the decrease in the volumes of the compression chambers between the point of cutoff from the inlet port and the point of communication with the discharge port.
  • FIG. l is a longitudinal section, partly in elevation, of a compressor embodying the invention and designed for creating and maintaining a vacuum corresponding to an absolute pressure of 71/2 to l0 millimeters of mercury and,
  • FIG. 2 is a section taken on line 2 2 of FIG. 1.
  • the housing structure indicated generally at 10 comprises a barrel portion 12 separated into low pressure and high pressure sections 12a and 12b, respectively.
  • the barrel portion of the housing structure is closed at the losw pressure end of the compressor by nie-ans of the end closure member 18 providing the inlet 20 for the admission of the Huid to be compressed.
  • the high pressure end of the barrel portion is closed by a high pressure end member 22 providing the discharge or outlet 24.
  • Rotatively mounted in the end members by suitable bearings are the male rotor 26 and the -femlale rotor 28, each of these rotor-s being divided into low pressure and high pressure sections of which the iow and high pressure sections of the male rotors 26a and 26h, are seen in FIG. 1.
  • the low pressure section of the housing structure is provided with la discharge port 30, the high pressure section being provided with an inlet port 32, and these ports
  • the rotors 26 and 28, of ythe male and female type char-acteristic of such compressors may be of any suitable conguration or profile appropriate for compressors of this kind, of which several specific profiles are well known in the art and of which the proboards shown in the aforementioned Nilsson Patent 2,622,787 is one, and which is here .illustrated in FIG. 2 .by ,way of example.
  • a sealing liquid may be introduced as is more or less diagrammatically indicated by the feed pipe 3S yfor liquid.
  • close running clearances are provided in known conventional fashion :between the inter-meshing rotors, with or without the aid of timing gears such as shown at 40 in FIG. l, and between the peripheries and ends of the rotors Iand the enclosing housing structure. All of this is old ⁇ and well known in the art and therefore need not be further described in detail herein.
  • liquid - is advantageously introduced into the working space of the compressor for the purpose of aiding in sealing the running clearance spaces and also for directly cooling the contents of the compression chambers to reduce the temperature rise thereof as the work of compression is done thereon.
  • introduction of such -liquid is indicated diagrammatically by the supply pipe 42 delivering a spray of liquid into the compressor intake, although it wil-l be understood that other and equivalent known means and methods for introducing liquid into lthe compressor, -such for example, as that disclosed in Nilsson et al. Patent 3,129,877 may be employed.
  • liquid deriving from condensated vapour may be carried oft' from -the conduit 34 interconnecting the two compressor stages, for instance, as diagrammatically indicated in FIG. l, to a steam condenser 44 from which the fiuid to be compressed may be derived.
  • any appropriate liquid may be employed depending upon the nature of the elastic iluid being evacuated, and the fluid, if any, entrained therewith.
  • water -is of course appropriate whereas for example in ythe case of the vacuum casting of steel, lubricating oil may be indicated.
  • oil nor water may be suitable, and in such instances other liquids such for example as products of ⁇ apiezones or the like, may be employe-d.
  • the speci-fic composition of the liquid is not germane to the invention.
  • the inbuilt compression ratio for the pre-compression or low pressure section of the compressor is in the preferred range of 2 or 3 to 1 and for rthe designed inlet pressure above noted the high pressure or main compression section is provided with rotors 1.2 times the length of the rotors of the loiw pressure section, the low pressure section having rotors, the lands and grooves of which have a tot-al wrap angle of 250 in the male rotor, while the total wrap angle of the lands and grooves of the male rotor of the high pressure section is 300.
  • the length of the rotors of the high pressure section would be less relative to that of the rotors of the low press-ure section and might well result in ⁇ a compressor designed in which the high pressure section is .actually shorter rather than longer than the low p-ressure section.
  • the pressure ratio for the precompression stage should not exceed 5 to 1 and is preferably considered below that since the benefits to be derived from the high volumetric efficiency of a low compression ratio are rapidly diminished as the compression ratio is raised.
  • the total pressure rise between inlet and delivery pressure rather than compression ratio is the most useful value to be considered in determining what may be said to be the utility yrange of the invention, since small variations in the actual val-ues of the inlet pressures result in very la-rge variations in ⁇ the values of the overall compression ratios required to deliver .to atmosphere.
  • the pressure ratio maintained in the precompression stage is in the preferred range of 2 or 3 to 1, the percentage of the total pressure rise that is effected i-n the pre-compression stage will be materially below the 15% limit, even if the installation is operated with an inlet pressure materially above one inch of mercury, which may be, according to the table previously referred to, the most economical pressure for a steam turbine condenser operating with condensing water of higher than usual temperature.
  • the design and operation of the apparatus should be carried out so that the pressure ratio of the pre-compression stage will be within the range of 2 or 3 to 1 and so that the pressure rise effected in the pre-compression stage will not exceed the order of 5% of the total pressure rise, representing approximately the range between 3.5% and 7% that would be obtained if the pre-compression ratio was 2 to 1 and 3 to l, respectively, and the pressure i-n the inlet of the Vacuum pump was one inch of mercury.
  • the pressure rise in the precompression stage will be within the range of 1% to 3%, or about 2%, of the total pressure rise which percentage is the preferred one for this range of vacuum.
  • a multiple stage vacuum pump for compressing an elastic fluid from a sub-atmospheric inlet pressure to a delivery pressure for discharge to ambient atmosphere, comprising a main compression stage of the helical screw rotor type having intermeshing male and female rotors providing apositive sealing and further comprising a precompression stage for pre-compressing said fiuid from said inlet pressure and delivering it at an intermediate pressure to said main compression stage, said pre-compression stage having a pressure ratio not exceeding 5 to 1 and operating to effect a pressure rise in said pre-compression stage not in excess of 15% 0f the total pressure rise from said inlet pressure to said delivery pressure.
  • a vacuum pump as defined in ⁇ claim 2 in which the rotors of the two stages comprise different rotor sections mounted in tandem on two rotor shafts,
  • a vacuum pump as defined in claim S in which a substantially positive seal is provided between the two rotor sections of each of the rotor shafts.
  • a vacuum pump as defined in claim 8 in which the two rotor sections of each of the rotor shafts have the same helix angle.
  • a method of evacuating elastic uid from a subatmospheric inlet pressure to a delivery pressure for discharge to ambient atmosphere by the aid of a multiplestage apositively sealed screw rotor compressor apparatus having a main compression stage with intermeshing male and female rotors, which comprises pre-compressing the uid in an initial precompression stage through a pressure ratio not exceeding 5 to 1 from said inlet pressure to an intermediate pressure and delivering said fluid at said intermediate pressure to said main compression stage in which the fluid is compressed from said intermediate pressure to said delivery pressure, the pressure rise from said inlet pressure to said intermediate pressure effected in said pre-compression stage not exceeding 15% of the total pressure rise from said inlet pressure to said delivery pressure.

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US519630A 1959-09-08 1966-01-10 Vacuum pump of the screw rotor type and method for operating the same Expired - Lifetime US3265293A (en)

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3462072A (en) * 1967-05-03 1969-08-19 Svenska Rotor Maskiner Ab Screw rotor machine
US3535057A (en) * 1968-09-06 1970-10-20 Esper Kodra Screw compressor
US3975123A (en) * 1973-09-03 1976-08-17 Svenska Rotor Maskiner Aktiebolag Shaft seals for a screw compressor
US4153395A (en) * 1976-09-04 1979-05-08 Howden Compressors Limited Compressors
WO1995018945A1 (en) * 1994-01-10 1995-07-13 Fresco Anthony N Cooling and sealing rotary screw compressors
DE19543879A1 (de) * 1995-11-24 1997-05-28 Guenter Kirsten Schraubenverdichter mit Flüssigkeitseinspritzung
US5641280A (en) * 1992-12-21 1997-06-24 Svenska Rotor Maskiner Ab Rotary screw compressor with shaft seal
US5653585A (en) * 1993-01-11 1997-08-05 Fresco; Anthony N. Apparatus and methods for cooling and sealing rotary helical screw compressors
WO2003093678A1 (en) * 2002-05-03 2003-11-13 Piab Ab Vacuum pump and method for generating sub-pressure
US20040062668A1 (en) * 2001-06-22 2004-04-01 Ghh-Rand Schraubenkompressoren Gmbh Two-stage screw compressor
US20040184911A1 (en) * 2001-05-29 2004-09-23 Olav Hofseth Liquid seal pump of the helical screw type
US20080152524A1 (en) * 2005-06-29 2008-06-26 Mayekawa Mfg. Co., Ltd. Oil supply method of two-stage screw compressor, two-stage screw compressor applying the method, and method of operating refrigerating machine having the compressor
US20100031824A1 (en) * 2007-03-15 2010-02-11 Ho-Young Cho Vacuum system using a filter cartridge
FR3129991A1 (fr) * 2021-12-08 2023-06-09 Pfeiffer Vacuum Ligne de vide, dispositif de pompage destiné à être raccordé à la ligne de vide et installation comportant la ligne de vide

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4714418A (en) * 1984-04-11 1987-12-22 Hitachi, Ltd. Screw type vacuum pump

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1698802A (en) * 1924-04-07 1929-01-15 Montelius Carl Oscar Josef Device for transferring energy to or from alpha fluid
US1734779A (en) * 1928-01-11 1929-11-05 Diming Company Pump
US2492075A (en) * 1945-10-30 1949-12-20 Kinney Mfg Company Vacuum pump
US2592476A (en) * 1948-02-07 1952-04-08 Laval Steam Turbine Co Series arrangement of positive and nonpositive screw pumps
US2622787A (en) * 1947-07-16 1952-12-23 Jarvis C Marble Helical rotary engine
US2691482A (en) * 1952-07-17 1954-10-12 Equi Flow Inc Method and apparatus for compressing and expanding gases
US2693763A (en) * 1951-10-25 1954-11-09 Laval Steam Turbine Co Nonpositive screw pump or motor
US2721694A (en) * 1954-01-29 1955-10-25 New York Air Brake Co First stage mechanical pump for use in a two stage vacuum pumping system
GB832386A (en) * 1956-05-17 1960-04-06 Svenska Rotor Maskiner Ab Improvements in rotary displacement machines
US2975963A (en) * 1958-02-27 1961-03-21 Svenska Rotor Maskiner Ab Rotor device
US3073514A (en) * 1956-11-14 1963-01-15 Svenska Rotor Maskiner Ab Rotary compressors
US3074624A (en) * 1960-03-11 1963-01-22 Svenska Rotor Maskiner Ab Rotary machine
US3084851A (en) * 1960-02-29 1963-04-09 Svenska Rotor Maskiner Ab Rotary machine
US3121530A (en) * 1959-08-11 1964-02-18 Heraeus Gmbh W C High vacuum pumps
US3129877A (en) * 1956-05-17 1964-04-21 Svenska Rotor Maskiner Ab Rotary piston, positive displacement compressor
US3138320A (en) * 1959-01-15 1964-06-23 Svenska Roytor Maskiner Aktieb Fluid seal for compressor

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1698802A (en) * 1924-04-07 1929-01-15 Montelius Carl Oscar Josef Device for transferring energy to or from alpha fluid
US1734779A (en) * 1928-01-11 1929-11-05 Diming Company Pump
US2492075A (en) * 1945-10-30 1949-12-20 Kinney Mfg Company Vacuum pump
US2622787A (en) * 1947-07-16 1952-12-23 Jarvis C Marble Helical rotary engine
US2592476A (en) * 1948-02-07 1952-04-08 Laval Steam Turbine Co Series arrangement of positive and nonpositive screw pumps
US2693763A (en) * 1951-10-25 1954-11-09 Laval Steam Turbine Co Nonpositive screw pump or motor
US2691482A (en) * 1952-07-17 1954-10-12 Equi Flow Inc Method and apparatus for compressing and expanding gases
US2721694A (en) * 1954-01-29 1955-10-25 New York Air Brake Co First stage mechanical pump for use in a two stage vacuum pumping system
GB832386A (en) * 1956-05-17 1960-04-06 Svenska Rotor Maskiner Ab Improvements in rotary displacement machines
US3129877A (en) * 1956-05-17 1964-04-21 Svenska Rotor Maskiner Ab Rotary piston, positive displacement compressor
US3073514A (en) * 1956-11-14 1963-01-15 Svenska Rotor Maskiner Ab Rotary compressors
US2975963A (en) * 1958-02-27 1961-03-21 Svenska Rotor Maskiner Ab Rotor device
US3138320A (en) * 1959-01-15 1964-06-23 Svenska Roytor Maskiner Aktieb Fluid seal for compressor
US3121530A (en) * 1959-08-11 1964-02-18 Heraeus Gmbh W C High vacuum pumps
US3084851A (en) * 1960-02-29 1963-04-09 Svenska Rotor Maskiner Ab Rotary machine
US3074624A (en) * 1960-03-11 1963-01-22 Svenska Rotor Maskiner Ab Rotary machine

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3462072A (en) * 1967-05-03 1969-08-19 Svenska Rotor Maskiner Ab Screw rotor machine
US3535057A (en) * 1968-09-06 1970-10-20 Esper Kodra Screw compressor
US3975123A (en) * 1973-09-03 1976-08-17 Svenska Rotor Maskiner Aktiebolag Shaft seals for a screw compressor
US4153395A (en) * 1976-09-04 1979-05-08 Howden Compressors Limited Compressors
US5641280A (en) * 1992-12-21 1997-06-24 Svenska Rotor Maskiner Ab Rotary screw compressor with shaft seal
US5653585A (en) * 1993-01-11 1997-08-05 Fresco; Anthony N. Apparatus and methods for cooling and sealing rotary helical screw compressors
WO1995018945A1 (en) * 1994-01-10 1995-07-13 Fresco Anthony N Cooling and sealing rotary screw compressors
DE19543879A1 (de) * 1995-11-24 1997-05-28 Guenter Kirsten Schraubenverdichter mit Flüssigkeitseinspritzung
DE19543879C2 (de) * 1995-11-24 2002-02-28 Guenter Kirsten Schraubenverdichter mit Flüssigkeitseinspritzung
US7029231B2 (en) * 2001-05-29 2006-04-18 Jets As Liquid seal pump of the helical screw type
US20040184911A1 (en) * 2001-05-29 2004-09-23 Olav Hofseth Liquid seal pump of the helical screw type
US6991440B2 (en) * 2001-06-22 2006-01-31 Ghh-Rand Schraubenkompressoren Gmbh Two-stage screw compressor
US20040062668A1 (en) * 2001-06-22 2004-04-01 Ghh-Rand Schraubenkompressoren Gmbh Two-stage screw compressor
US20050232783A1 (en) * 2002-05-03 2005-10-20 Peter Tell Vacuum pump and method for generating sub-pressure
WO2003093678A1 (en) * 2002-05-03 2003-11-13 Piab Ab Vacuum pump and method for generating sub-pressure
US7452191B2 (en) 2002-05-03 2008-11-18 Piab Ab Vacuum pump and method for generating sub-pressure
US20080152524A1 (en) * 2005-06-29 2008-06-26 Mayekawa Mfg. Co., Ltd. Oil supply method of two-stage screw compressor, two-stage screw compressor applying the method, and method of operating refrigerating machine having the compressor
US20100089078A1 (en) * 2005-06-29 2010-04-15 Mayekawa Mfg. Co., Ltd. Oil supply method of two-stage screw compressor, two-stage screw compressor applying the method, and method of operating refrigerating machine having the compressor
US7722346B2 (en) * 2005-06-29 2010-05-25 Mayekawa Mfg. Co., Ltd. Oil supply method of two-stage screw compressor, two-stage screw compressor applying the method, and method of operating refrigerating machine having the compressor
US8277207B2 (en) 2005-06-29 2012-10-02 Mayekawa Mfg. Co., Ltd. Oil supply method of two-stage screw compressor, two-stage screw compressor applying the method, and method of operating refrigerating machine having the compressor
US20100031824A1 (en) * 2007-03-15 2010-02-11 Ho-Young Cho Vacuum system using a filter cartridge
US8257456B2 (en) 2007-03-15 2012-09-04 Korea Pneumatic System Co., Ltd. Vacuum system using a filter cartridge
FR3129991A1 (fr) * 2021-12-08 2023-06-09 Pfeiffer Vacuum Ligne de vide, dispositif de pompage destiné à être raccordé à la ligne de vide et installation comportant la ligne de vide
WO2023104476A1 (en) * 2021-12-08 2023-06-15 Pfeiffer Vacuum Vacuum line, pumping device intended to be connected to the vacuum line and installation comprising the vacuum line

Also Published As

Publication number Publication date
DE1403596A1 (de) 1968-11-28
GB966752A (en) 1964-08-12
CH393617A (de) 1965-06-15

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