EP0245427B1 - Compresseur a rotor helicoidal et installation frigorifique - Google Patents

Compresseur a rotor helicoidal et installation frigorifique Download PDF

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Publication number
EP0245427B1
EP0245427B1 EP19860906989 EP86906989A EP0245427B1 EP 0245427 B1 EP0245427 B1 EP 0245427B1 EP 19860906989 EP19860906989 EP 19860906989 EP 86906989 A EP86906989 A EP 86906989A EP 0245427 B1 EP0245427 B1 EP 0245427B1
Authority
EP
European Patent Office
Prior art keywords
compressor
port
rotor
outlet port
groove
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19860906989
Other languages
German (de)
English (en)
Other versions
EP0245427A1 (fr
Inventor
Lars SJÖHOLM
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Svenska Rotor Maskiner AB
Original Assignee
Svenska Rotor Maskiner AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Svenska Rotor Maskiner AB filed Critical Svenska Rotor Maskiner AB
Publication of EP0245427A1 publication Critical patent/EP0245427A1/fr
Application granted granted Critical
Publication of EP0245427B1 publication Critical patent/EP0245427B1/fr
Expired legal-status Critical Current

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Classifications

    • 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
    • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
    • F04C28/10—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by changing the positions of the inlet or outlet openings with respect to the working chamber
    • F04C28/12—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by changing the positions of the inlet or outlet openings with respect to the working chamber using sliding valves
    • F04C28/125—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by changing the positions of the inlet or outlet openings with respect to the working chamber using sliding valves with sliding valves controlled by the use of fluid other than the working fluid

Definitions

  • the present invention relates to a screw compressor, especially adapted for use within a refrigeration plant with two stage throttling.
  • a compressor comprises a casing with a working space generally composed of intersecting bores with parallel axes enclosed by barrel and end walls and provided with spaced apart inlet and outlet ports for communication with inlet and outlet channels, respectively.
  • Rotors each having helical lands and intervening grooves, are disposed in the bores and intermesh in pair.
  • One rotor of the pair is of male rotor type formed such that at least the major portion of each land and groove is located outside the pitch circle of the rotor.
  • the other rotor is of female rotor type formed such that at the major portion of each land and groove is located inside the pitch circle of the rotor.
  • Two communicating groove portions thus form a chevron-shaped chamber having its base end disposed in a plane transverse to the axes of the bores and adjacent to the outlet port.
  • the compressor is provided with capacity control means comprising a bleed port and a valve member having an axially displaceable control edge defining the actual size of the port.
  • the compressor is further provided with means for additional supply of working fluid at a pressure higher than the normal inlet pressure.
  • a compressor of the above type for use in a refrigeration plant is known from Swedish patent 382 663.
  • This compressor is provided with an axially slidable valve of the type shown in Swedish patent 366 375, i.e. a valve member disposed in the barrel wall of the working space and including the intersection line between the bores so that the valve simultaneously adjusts a bleed port at one end and the outlet port at the other end.
  • This valve member is provided with openings, for additional supply of gas from the first throttling stage, situated so that at maximum capacity the openings are disposed on such a distance from the inlet end wall that they communicate with a chevron-shaped chamber first after the initiation of the compression.
  • a valve member of the type shown decreases for a certain displacement thereof the outlet volume, i.e. the volume of the chevron-shaped chamber when opening towards the outlet port, and the inlet volume, i.e. the volume of the chevron-shaped chamber when cut off from the bleed port, with the same quantity.
  • the ratio between the inlet volume and the outlet volume, the built-in volume ratio thus increases with increasing bleed off. This effect is further accentuated when additional working fluid is supplied after the cut off from the bleed port.
  • the bleed port In order to avoid too high built-in volume ratios and over-compression resulting therefrom the bleed port must when opened momentarily mean a considerable reduction of the inlet volume eventhough this on the other hand means a low built-in volume ratio resulting in under-compression.
  • the possibility to vary the volumetric capacity of a compressor without too high losses in the adiabatic efficiency is thus limited.
  • With additional supply openings in the valve member there is a further problem that those openings in order to maintain a higher pressure therein than the inlet pressure must be located on a considerable distance from the edge thereof controlling the bleed port. Consequently the bleed port in such a compressor must be situated closer to the inlet end wall than in normal compressors. In other words the reduction of the inlet volume when opening the bleed port can only be a fraction of that in earlier known compressors and consequently the range for variation of the volumetric capacity will be further reduced.
  • the object of the present invention is to provide a compressor of the type specified where the range of capacity variation with high adiabatic efficiency is considerably extended simultaneously as the intermediate, additional supply pressure is on a steady high level required for an optimum process, which means that the over-all efficiency of the plant at part load is kept on a much higher level than that obtained by earlier used compressors.
  • said capacity control means is situated peripherally out of the outlet port, that said additional supply means comprises a port within said capacity control valve located at an axial distance from said control edge at least corresponding to the axial distance between two consecutive lands of the facing rotor, and that separate means are provided for selective adjustment of the outlet port.
  • a further improvement of the efficiency of the compressor may be obtained by providing the outlet port valve with injection means for a cooling and sealing liquid, said injection means being located such that it never communicates with any of the inlet and outlet ports or with the additional supply means, at least at low capacity reduction conditions.
  • the compressor shown in Figs. 1 and 2 comprises a male rotor 10 provided with five helical lands 12 and intervening grooves 14-and a female rotor 16 intermeshing therewith and provided with six helical lands 18 each enclosing a rotor and intervening grooves 20.
  • the rotors 10, 16 are mounted in a housing having low and high pressure end wall members and a barrel member 22 comprising two intersecting bores each enclosing a rotor.
  • the housing is provided with an inlet port 24 at the low pressure end and extending as a relieved portion into the barrel wall and an outlet port 26 at the high pressure end.
  • the barrel member 22 there are further two circular grooves intersecting with the barrel wall and each enclosing an axially adjustable valve member 28, 30 sealingly cooperating with the facing rotor 10, 16.
  • One of the valve grooves forms the outlet port 26 and a pressure adjusting valve member 28 enclosed therein is provided with a control edge 32 defining the actual shape and size of the outlet port 26.
  • the other valve groove is located in the wall of the bore enclosing the male rotor 10, peripherally out of the area of the outlet port 26 and encloses a capacity adjusting valve member 30 provided with a control edge 34 facing the inlet port 24 and at full capacity defining a part of the edge thereof, whereas at reduced capacity this edge defines the size and shape of a bleed port 36 communicating with the inlet port 24.
  • the capacity valve 30 is further provided with an opening 38 for supply of additional working fluid at an intermediate pressure higher than that of the fluid supplied through the inlet port 24.
  • This additional supply opening 38 is located at an axial distance from the control edge 34 corresponding to the axial distance between two consecutive lands 12 of the facing rotor 10.
  • the pressure valve 28 is similarly provided with an opening 40 for supply of a cooling and sealing liquid, which in a refrigeration compressor may consist of liquefied working fluid preferably having a temperature below the condensing temperature, which will improve the efficiency of the compressor.
  • a cooling and sealing liquid which in a refrigeration compressor may consist of liquefied working fluid preferably having a temperature below the condensing temperature, which will improve the efficiency of the compressor.
  • a refrigeration plant which comprises a compressor 42 of the type specified above, a condenser 44 connected to the compressor outlet port 26, a first throttling valve 46 located between the condenser 44 and a flash chamber 48, which in turn is connected on the gas side to the intermediate pressure supply opening 38 of the compressor and on the liquid side to a second throttling valve 50, and an evaporator 52 connected to the second throttling valve 50 and the low pressure compressor inlet 24.
  • the built-in volume ratio (V i ) is shown as a function of the position (L) of the control edge 34 when moving from the position for maximum capacity to the position for minimum capacity, where a fixed edge of the axial portion may decide the size of the outlet port 26.
  • the built-in volume ratio will be kept practically constant at all capacities which means that the efficiency of the compressor can be kept on a high level over a wide field of part load capacity, simultaneously as the so called "economizer" effect is maintained at an optimum level.
  • the corresponding function for compressors as shown in Swedish patent 382 663 and in US patent 3 568 466, supplemented by a conventional capacity valve as shown in US patent 3 314 597, respectively.
  • thermodynamical process within the plant shown in Fig. 3 is indicated in Fig. 5 as a diagram showing the relation between the pressure (log p) and the enthalpy (i).
  • the different points thereof related to specific details indicated in the plant shown in Fig. 3 has been denoted by the same reference numbers.
  • the line 42 corresponds to the compressor, with its inlet port, additional supply opening, and outlet port at point 24, 38 and 26, respectively.
  • Line 44 corresponds to the condenser
  • point 46 corresponds to the first throttling valve
  • point 48 to the flash chamber
  • point 50 corresponds to the second throttling valve
  • line 52 corresponds to the evaporator.
  • the process drawn in continuous lines indicates the process at full load and at part load according to the invention.
  • the invention thus results not only in an improved compressor efficiency but also when used in a refrigeration plant in an improved process efficiency, which means a considerably higher total efficiency of the plant.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Abstract

Compresseur hélicoïdal, surtout adapté à fonctionner en liaison avec une installation frigorifique. Le compresseur est constitué d'un boîtier pourvu d'un espace de travail généralement sous la forme d'alésages se chevauchant à axes parallèles, et pourvu d'orifices d'entrée et de sortie espacés l'un de l'autre, ainsi que d'une paire de rotors mâle et femelle, dont chacun possède des parties hélicoïdales pleines et des rainures intermédiaires. Le compresseur est doté d'un moyen de réglage de la capacité, sous la forme d'un orifice de purge et d'un élément à soupape dont le rebord de régulation est déplaçable dans le sens axial et qui définit la dimension réelle de l'orifice, ainsi que de moyens pour fournir une quantité supplémentaire de fluide de travail à une pression supérieure à la pression d'entrée normale. Le moyen de régulation de la capacité est situé périphériquement à l'extérieur de l'orifice de sortie, et le moyen d'alimentation supplémentaire comporte un orifice à l'intérieur de la soupape de régulation de la capacité, situé à une distance axiale par rapport au rebord de régulation qui correspond au moins à la distance axiale entre deux parties pleines consécutives du rotor opposé. De plus, le compresseur est pourvu de moyens séparés pour le réglage sélectif de l'orifice de sortie.

Claims (5)

1. Compresseur à rotor hélicoïdal, particulièrement adapté pour être utilisé dans une installation frigorifique à laminage en deux étages, comprenant un carter muni d'un espace de travail généralement composé d'alésages 3 intersection à axes parallèles, enfermés dans une enveloppe de cylindre (22) et des fonds et pourvu d'orifices d'entrée (24) et de sortie (26) espacés entre eux, communiquant respectivement avec des canaux d'entrée et de sortie, et des rotors (10, 16), chacun d'eux muni de portées hélicoïdales (12, 18) et de rainures intermédiaires (14, 20) ménagées dans lesdits alésages et engrenant par paire, un rotor (10) de la paire étant un rotor de type mâle agencé de manière que la partie principale de chaque portée (12) et rainure (14) au moins soit située à l'extérieur du cercle primitif du rotor, l'autre rotor (16) étant du type de rotor femelle, agencé de manière que la partie principale de chaque portée (18) et rainure (20) au moins soit située à l'intérieur du cercle primitif du rotor, de sorte que deux parties de rainures en communication constituent une chambre en forme de chevron dont l'extrémité de base est disposée dans un plan transversal aux axes des alésages et adjacent à l'orifice de sortie (26), ledit compresseur étant pourvu de moyens de réglage de capacité (30, 36) comprenant un orifice de purge (36) et un élément de tiroir (30) possédant une arête de commande (34) déplaçable axialement, définissant la dimension effective de l'orifice (24) et des moyens d'alimentation supplémentaire de fluide de travail sous une pression supérieure à la pression normale d'entrée, caractérisé en ce que lesdits moyens de réglage de capacité (30, 36) sont situés périphériquement à l'extérieur de l'orifice de sortie (26), que lesdits moyens d'alimentation supplémentaire comprennent un orifice (38) dans ledit tiroir de réglage de capacité (30), situés à une distance axiale de ladite arête de commande (34) correspondant au moins à la distance axiale entre deux portées consécutives (12) du rotor opposé (10) et que des moyens séparés (28) sont prévus pour le réglage sélectif de l'orifice de sortie (26).
2. Compresseur selon la revendication 1, dans lequel deux rainures axiales espacées sont prévues dans la paroi de cylindre (22) de l'espace de travail s'étendant d'une paroi d'extrémité à l'autre, une première rainure communiquant avec l'orifice de sortie (26) étant située dans une zone adjacente à la ligne d'intersection correspondante entre lesdits alésages et enfermant un élément en forme de tiroir (28), réglable axialement, s'adaptant à la paroi de cylindre (22) et comportant une arête de commande (32) définissant la dimension et la position de l'orifice de sortie (26), la seconde rainure, parallèle à la première rainure, étant en communication avec l'orifice d'entrée (24) et enfermant un élément de tiroir (30), réglable axialement, s'adaptant à la paroi de cylindre (22) et traversant, de façon étanche, le fond de l'orifice de sortie (26).
3. Compresseur selon la revendication 2, dans lequel ledit élément de tiroir (28) de l'orifice de sortie (26) est pourvu d'une ouverture (40) d'injection de fluide de travail liquéfié, ladite ouverture (40) étant située à une distance axiale de ladite arête de commande (32) correspondant au moins à la distance axiale entre deux portées consécutives (18) d'un rotor (16).
4. Compresseur selon la revendication 2 ou 3, dans lequel ladite première rainure comprend une partie principale au moins faisant face au rotor femelle (16), tandis que la seconde rainure est tournée vers le rotor mâle (10).
5. Installation frigorifique à laminage à deux étages, comprenant un compresseur tel que défini dans l'une quelconque des précédentes revendications.
EP19860906989 1985-11-15 1986-11-14 Compresseur a rotor helicoidal et installation frigorifique Expired EP0245427B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB858528211A GB8528211D0 (en) 1985-11-15 1985-11-15 Screw compressor
GB8528211 1985-11-15

Publications (2)

Publication Number Publication Date
EP0245427A1 EP0245427A1 (fr) 1987-11-19
EP0245427B1 true EP0245427B1 (fr) 1989-10-04

Family

ID=10588296

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860906989 Expired EP0245427B1 (fr) 1985-11-15 1986-11-14 Compresseur a rotor helicoidal et installation frigorifique

Country Status (5)

Country Link
EP (1) EP0245427B1 (fr)
AU (1) AU6732287A (fr)
DE (1) DE3666074D1 (fr)
GB (1) GB8528211D0 (fr)
WO (1) WO1987003048A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5228301A (en) * 1992-07-27 1993-07-20 Thermo King Corporation Methods and apparatus for operating a refrigeration system
US5246357A (en) * 1992-07-27 1993-09-21 Westinghouse Electric Corp. Screw compressor with oil-gas separation means
WO2008112554A1 (fr) * 2007-03-09 2008-09-18 Johnson Controls Technology Company Système de réfrigération

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO117317B (fr) * 1964-03-20 1969-07-28 Svenska Rotor Maskiner Ab
SE338576B (fr) * 1968-05-06 1971-09-13 Stal Refrigeration Ab
SE366375B (fr) * 1972-06-30 1974-04-22 Stal Refrigeration Ab
SE382663B (sv) * 1974-04-11 1976-02-09 Stal Refrigeration Ab Sett att fora in mellantryckgas i en skruvkylkompressor jemte skruvkompressor for genomforande av settet.

Also Published As

Publication number Publication date
AU6732287A (en) 1987-06-02
GB8528211D0 (en) 1985-12-18
EP0245427A1 (fr) 1987-11-19
WO1987003048A1 (fr) 1987-05-21
DE3666074D1 (en) 1989-11-09

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