EP0478939A2 - Two-stage rotary compressor for refrigerating plants - Google Patents

Two-stage rotary compressor for refrigerating plants Download PDF

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Publication number
EP0478939A2
EP0478939A2 EP91114044A EP91114044A EP0478939A2 EP 0478939 A2 EP0478939 A2 EP 0478939A2 EP 91114044 A EP91114044 A EP 91114044A EP 91114044 A EP91114044 A EP 91114044A EP 0478939 A2 EP0478939 A2 EP 0478939A2
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EP
European Patent Office
Prior art keywords
pressure
compression unit
low
pressure compression
oil
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.)
Withdrawn
Application number
EP91114044A
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German (de)
French (fr)
Other versions
EP0478939A3 (en
Inventor
Giulio Contaldi
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.)
Ing Enea Mattei SpA
Original Assignee
Ing Enea Mattei SpA
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 Ing Enea Mattei SpA filed Critical Ing Enea Mattei SpA
Publication of EP0478939A2 publication Critical patent/EP0478939A2/en
Publication of EP0478939A3 publication Critical patent/EP0478939A3/en
Withdrawn legal-status Critical Current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
    • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • F04C29/02—Lubrication; Lubricant separation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B31/00—Compressor arrangements
    • F25B31/002—Lubrication
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B40/00—Subcoolers, desuperheaters or superheaters
    • F25B40/02—Subcoolers

Definitions

  • the present invention relates to a two-stage rotary compressor for refrigerating plants, of the type comprising a vane rotor, by means of which it is possible to obtain high volumetric efficiency and substantial savings in energy while still producing the same number of frigories.
  • the object of the invention is to provide a two-stage compressor in the form of a single rotary machine, comprising two functionally and structurally integrated compression units which use a single control motor and a single pumping means for circulating the lubricating oil and whose compression ratios are notably reduced according to the geometric mean between the minimum pressure and maximum pressure of the refrigeration cycle.
  • a two-stage rotary compressor for refrigerating plants comprising a first low-pressure vane compression unit and a second high-pressure vane compression unit, in which the rotors are connected to a single control motor and in which the lubricating oil circuit comprises an oil collection chamber positioned between the two compression units, said oil chamber being maintained at an intermediate pressure and being connected respectively to the delivery side of the low-pressure compression unit via a first oil separator and to a feeding pumping means which supplies the lubricating oil to the high-pressure compression unit, there being provided moreover a connection for supplying the lubricating oil from the delivery side of the high-pressure compression unit to the low-pressure unit, comprising an oil separator.
  • a two-stage rotary compressor of the radial vane type comprising a first compression unit 11, hereinbelow also called low-pressure compression unit BP, and a second compression unit 12, hereinbelow also called high-pressure compression unit AP, the rotors 13 and 14 of which are mechanically connected together by means of an intermediate coupling 15 so as to be rotated by a single electric motor 16.
  • the intermediate pressure of the two-stage cycle corresponding to the delivery pressure of the low-pressure compression unit, is designed so as to be equivalent to the geometric mean between the minimum pressure of the cycle at the intake side of the low-pressure unit, and the maximum pressure of the cycle at the delivery side of the high-pressure compressor.
  • the two compression units 11 and 12 in a similar manner to conventional vane compressors, thus comprise a chamber inside which a vane rotor 13, 14 rotates eccentrically, a refrigerant such as freon or the like being continuously sucked in and compressed by the two compression units 11, 12, along with the lubricating oil, then separated and made to circulate inside a refrigerating plant as shown.
  • This plant substantially comprises a condenser 18 connected to the delivery side of the high-pressure compression unit 12 via a high-pressure separator 19.
  • the refrigerant before being supplied to the low-pressure evaporator 20 is subcooled in a heat exchanger 21 operating at an intermediate pressure between the minimum pressure of the cycle, corresponding to the intake pressure of the low-pressure unit 13, and the maximum pressure, corresponding to the delivery pressure of the high-pressure unit 14. Therefore the refrigerant leaving the evaporator 20 is returned to the intake side of the low-pressure compression unit 11, and from here to the intake side of the high-pressure compression unit 12, via an oil separator 22, having an intermediate pressure, and a mixer 23 forming part of a circuit for subcooling the refrigerant.
  • This circuit comprises a heat exchanger 21 whose secondary circuit is supplied with the same refrigerant branched from the line 24, so as to be supplied to the exchanger 21 via a lamination valve 25; 26 denotes a second branched lamination valve for humidification of the mixer 23.
  • lubrication of the two compression units 11 and 12 of the two-stage compressor 10 is obtained by means of an integrated circuit which makes use of the intermediate pressure of the cycle at the delivery side of the low-pressure compression unit.
  • a chamber 27 for collecting the lubricating oil 28 inside which the intermediate pressure of the cycle is maintained is provided between the low-pressure compression unit 11 and the high-pressure compression unit 12.
  • This chamber 27 for the lubricating oil forms a functionally and structurally integral part of the two-stage compressor according to the invention.
  • the chamber 27 is therefore connected to the delivery side of the low-pressure unit 11 via the conduit 22', the oil separator 22 and conduit 22''; at the same time, the bottom of the chamber 27 is connected to the oil circulating pump 17 which supplies the oil to the delivery side of the high-pressure compression unit 12.
  • the low-pressure compression unit 11 is further supplied via the conduit 17'' with lubricating oil from the high-pressure oil separator 19 via the lines 19' and 19''.
  • the various differences in pressure of the cycle, and in particular the intermediate pressure inside the chamber 27 are used to supply the lubricating oil to the intake side of the feeding pump 17. It is therefore possible to use normal commercially available pumping devices even if they have a relatively low pressure differential insufficient for compressors with high-compression ratios, thus reducing considerably the costs of the compressor.
  • the intermediate-pressure oil chamber 27 is located between the low-pressure unit 11 and the high-pressure unit 12, defining a chamber for collecting the lubricating oil. Therefore, advantageously this oil chamber 27 surrounds the coupling 15 connecting the shafts of the rotors, thus making it possible to achieve a two-stage compressor with an integrated structure, which occupies a limited amount of space and is able to use conventionally designed compressors.
  • the ends of the two compression units 11 and 12 opposite to the intake ends of the compressor are directed towards the intermediate-pressure oil chamber 27. Therefore, on this side of the compression units, it is not necessary to provide any special seal since any leaks or seepages of gas are prevented by the said oil chamber 27.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Abstract

A two-stage rotary compressor for refrigerating plants comprising a first low-pressure compression unit (11) and a second high-pressure compression unit (12), the rotors (13, 14) of which are connected to a single control motor (16) and in which the lubricating oil circuit comprises an intermediate oil chamber (27) connected respectively to the delivery side of the low-pressure compression unit (11) via a first oil separator (22) and to a feeding pump (17) which supplies the lubricating oil to the high-pressure compression unit (12); the oil separated from the high-pressure delivery of the second compression unit (12) in turn supplies the low-pressure compression unit (11).

Description

  • The present invention relates to a two-stage rotary compressor for refrigerating plants, of the type comprising a vane rotor, by means of which it is possible to obtain high volumetric efficiency and substantial savings in energy while still producing the same number of frigories.
  • In small or medium-capacity refrigerating plants single rotary vane-type compressors are often used, in order to take advantage of the intrinsic features of this type of machine. In order to obtain low operating temperatures for a refrigerating plant, in general it is necessary to have high compression ratios, which are difficult to obtain using conventional rotary compressors other than those with notably low volumetric efficiency; it has also been proposed to use in tandem two identical compressors, each provided with its own control motor and own lubricating circuit, without however achieving a satisfactory or economic solution to the problem.
  • The object of the invention is to provide a two-stage compressor in the form of a single rotary machine, comprising two functionally and structurally integrated compression units which use a single control motor and a single pumping means for circulating the lubricating oil and whose compression ratios are notably reduced according to the geometric mean between the minimum pressure and maximum pressure of the refrigeration cycle.
  • The above can be achieved by means of a two-stage rotary compressor for refrigerating plants according to the present invention comprising a first low-pressure vane compression unit and a second high-pressure vane compression unit, in which the rotors are connected to a single control motor and in which the lubricating oil circuit comprises an oil collection chamber positioned between the two compression units, said oil chamber being maintained at an intermediate pressure and being connected respectively to the delivery side of the low-pressure compression unit via a first oil separator and to a feeding pumping means which supplies the lubricating oil to the high-pressure compression unit, there being provided moreover a connection for supplying the lubricating oil from the delivery side of the high-pressure compression unit to the low-pressure unit, comprising an oil separator.
  • The two-stage rotary compressor for refrigerating plants according to the present invention will be illustrated in greater detail hereinbelow, with reference to the accompanying drawing which shows in schematic form the entire refrigerating plant with the two-stage compressor according to the invention.
  • 10 denotes in its entirety a two-stage rotary compressor of the radial vane type, comprising a first compression unit 11, hereinbelow also called low-pressure compression unit BP, and a second compression unit 12, hereinbelow also called high-pressure compression unit AP, the rotors 13 and 14 of which are mechanically connected together by means of an intermediate coupling 15 so as to be rotated by a single electric motor 16. Since the power consumption of the compressor is a direct function of the two compression ratios, in order to minimise this power, the intermediate pressure of the two-stage cycle, corresponding to the delivery pressure of the low-pressure compression unit, is designed so as to be equivalent to the geometric mean between the minimum pressure of the cycle at the intake side of the low-pressure unit, and the maximum pressure of the cycle at the delivery side of the high-pressure compressor.
  • Therefore, a same compression ratio is obtained for both compressor units.
  • 17 denotes moreover a single pumping device for circulating the lubricating oil inside the two compressor units 11 and 12, making suitable use of the delivery pressures of both the compression units 11 and 12.
  • The two compression units 11 and 12, in a similar manner to conventional vane compressors, thus comprise a chamber inside which a vane rotor 13, 14 rotates eccentrically, a refrigerant such as freon or the like being continuously sucked in and compressed by the two compression units 11, 12, along with the lubricating oil, then separated and made to circulate inside a refrigerating plant as shown. This plant substantially comprises a condenser 18 connected to the delivery side of the high-pressure compression unit 12 via a high-pressure separator 19. From the condenser 18, the refrigerant before being supplied to the low-pressure evaporator 20 is subcooled in a heat exchanger 21 operating at an intermediate pressure between the minimum pressure of the cycle, corresponding to the intake pressure of the low-pressure unit 13, and the maximum pressure, corresponding to the delivery pressure of the high-pressure unit 14. Therefore the refrigerant leaving the evaporator 20 is returned to the intake side of the low-pressure compression unit 11, and from here to the intake side of the high-pressure compression unit 12, via an oil separator 22, having an intermediate pressure, and a mixer 23 forming part of a circuit for subcooling the refrigerant. This circuit comprises a heat exchanger 21 whose secondary circuit is supplied with the same refrigerant branched from the line 24, so as to be supplied to the exchanger 21 via a lamination valve 25; 26 denotes a second branched lamination valve for humidification of the mixer 23.
  • According to the present invention, lubrication of the two compression units 11 and 12 of the two-stage compressor 10, unlike conventional compressors, is obtained by means of an integrated circuit which makes use of the intermediate pressure of the cycle at the delivery side of the low-pressure compression unit. For this purpose, between the low-pressure compression unit 11 and the high-pressure compression unit 12, there is provided a chamber 27 for collecting the lubricating oil 28, inside which the intermediate pressure of the cycle is maintained. This chamber 27 for the lubricating oil forms a functionally and structurally integral part of the two-stage compressor according to the invention. The chamber 27 is therefore connected to the delivery side of the low-pressure unit 11 via the conduit 22', the oil separator 22 and conduit 22''; at the same time, the bottom of the chamber 27 is connected to the oil circulating pump 17 which supplies the oil to the delivery side of the high-pressure compression unit 12. Finally, the low-pressure compression unit 11 is further supplied via the conduit 17'' with lubricating oil from the high-pressure oil separator 19 via the lines 19' and 19''. In this way, the various differences in pressure of the cycle, and in particular the intermediate pressure inside the chamber 27, are used to supply the lubricating oil to the intake side of the feeding pump 17. It is therefore possible to use normal commercially available pumping devices even if they have a relatively low pressure differential insufficient for compressors with high-compression ratios, thus reducing considerably the costs of the compressor.
  • As previously mentioned, the intermediate-pressure oil chamber 27 is located between the low-pressure unit 11 and the high-pressure unit 12, defining a chamber for collecting the lubricating oil. Therefore, advantageously this oil chamber 27 surrounds the coupling 15 connecting the shafts of the rotors, thus making it possible to achieve a two-stage compressor with an integrated structure, which occupies a limited amount of space and is able to use conventionally designed compressors.
  • According to a further characteristic feature, in order to simplify further the problems associated with the seals, the ends of the two compression units 11 and 12 opposite to the intake ends of the compressor are directed towards the intermediate-pressure oil chamber 27. Therefore, on this side of the compression units, it is not necessary to provide any special seal since any leaks or seepages of gas are prevented by the said oil chamber 27.
  • From the above description and the illustration of the accompanying drawing it will thus be understood that a two-stage rotary compressor had been provided, comprising two blade compression units which are structurally and functionally integrated so as to form a single machine with separate rotors, lubrication and cooling of which is effected by making suitable use of the different pressures of the cycle, thus resulting in a simplified compressor design and reduced operating costs.

Claims (4)

  1. Two-stage rotary compressor for refrigerating plants, characterized by comprising a first low-pressure compression unit (11) with a vane-type rotor, and a second high-pressure compression unit (12) with a vane-type rotor, the rotors (13, 14) of said compression units (11,12) being connected together and to a common control motor (16), and in that the lubricating-oil circuit of the compressor (10) comprises an oil chamber (27) which is maintained at an intermediate pressure and is positioned between said low-pressure compression unit (11) and said high-pressure compression unit (12).
  2. Two-stage compressor according to Claim 1, characterized in that the oil chamber (27) is connected respectively to the delivery side of the low-pressure compression unit (11) via a feeding line (22',22'') comprising an oil separator (22) and to the oil input of the high-pressure compression unit (12), via a line (17',17'') comprising pumping means (17) and in that there is provided a connection (19',19'') supplying the lubricating oil from the delivery side of the high-pressure compression unit (12) to the oil input of the low-pressure compression unit (11).
  3. Two-stage compressor according to the preceding claims, characterized in that said oil chamber (27) surrounds the coupling (15) connecting the shafts of the rotors (13,14) of the two low-pressure and high-pressure units (11,12).
  4. Two-stage compressor according to Claim 1, characterized in that the ends of the low-pressure compression unit (11) and high-pressure compression unit (12) which are opposite to the refrigerant intake ends are protruding into said intermediate oil chamber (27).
EP19910114044 1990-10-03 1991-08-22 Two-stage rotary compressor for refrigerating plants Withdrawn EP0478939A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT2187890U 1990-10-03
IT2187890U IT220269Z2 (en) 1990-10-03 1990-10-03 TWO-STAGE ROTARY COMPRESSION FOR REFRIGERATING SYSTEMS

Publications (2)

Publication Number Publication Date
EP0478939A2 true EP0478939A2 (en) 1992-04-08
EP0478939A3 EP0478939A3 (en) 1992-04-22

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Family Applications (1)

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EP19910114044 Withdrawn EP0478939A3 (en) 1990-10-03 1991-08-22 Two-stage rotary compressor for refrigerating plants

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EP (1) EP0478939A3 (en)
IT (1) IT220269Z2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1157244A1 (en) * 1999-02-05 2001-11-28 Midwest Research Institute Refrigeration system with liquid injection desuperheating
EP1770341A3 (en) * 2005-09-30 2010-07-21 Sanyo Electric Co., Ltd. Refrigerant compressor and refrigerant cycle device including the same
US10309704B2 (en) 2013-11-25 2019-06-04 The Coca-Cola Company Compressor with an oil separator between compressing stages

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3168236A (en) * 1963-09-05 1965-02-02 Jaeger Machine Co Oil scavenging system for a rotary compressor
US3226949A (en) * 1964-05-05 1966-01-04 Worthington Corp Multi-zone refrigeration system and apparatus
GB1174370A (en) * 1968-05-07 1969-12-17 Stal Refrigeration Ab A Compressor Unit.
DE2230064A1 (en) * 1971-06-21 1973-01-11 Vilter Manufacturing Corp ROTARY SCREW MOTOR
US3859815A (en) * 1973-10-12 1975-01-14 Maekawa Seisakusho Kk Two-stage compression apparatus
FR2381983A1 (en) * 1977-02-28 1978-09-22 Luft U Kaeltetechnik Veb K Refrigerator with multi-stage compressor - has oil collectors coupled via crankcase and pump to supply oil for lifting valve actuators
JPS57122193A (en) * 1981-01-21 1982-07-29 Hitachi Ltd Oil replenishing device in refrigerator

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3168236A (en) * 1963-09-05 1965-02-02 Jaeger Machine Co Oil scavenging system for a rotary compressor
US3226949A (en) * 1964-05-05 1966-01-04 Worthington Corp Multi-zone refrigeration system and apparatus
GB1174370A (en) * 1968-05-07 1969-12-17 Stal Refrigeration Ab A Compressor Unit.
DE2230064A1 (en) * 1971-06-21 1973-01-11 Vilter Manufacturing Corp ROTARY SCREW MOTOR
US3859815A (en) * 1973-10-12 1975-01-14 Maekawa Seisakusho Kk Two-stage compression apparatus
FR2381983A1 (en) * 1977-02-28 1978-09-22 Luft U Kaeltetechnik Veb K Refrigerator with multi-stage compressor - has oil collectors coupled via crankcase and pump to supply oil for lifting valve actuators
JPS57122193A (en) * 1981-01-21 1982-07-29 Hitachi Ltd Oil replenishing device in refrigerator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 6, no. 216 (M-168)29 October 1982 & JP-A-57 122 193 ( HITACHI ) 29 July 1982 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1157244A1 (en) * 1999-02-05 2001-11-28 Midwest Research Institute Refrigeration system with liquid injection desuperheating
EP1157244A4 (en) * 1999-02-05 2002-04-17 Midwest Research Inst Refrigeration system with liquid injection desuperheating
EP1770341A3 (en) * 2005-09-30 2010-07-21 Sanyo Electric Co., Ltd. Refrigerant compressor and refrigerant cycle device including the same
US10309704B2 (en) 2013-11-25 2019-06-04 The Coca-Cola Company Compressor with an oil separator between compressing stages

Also Published As

Publication number Publication date
IT9021878U1 (en) 1992-04-03
EP0478939A3 (en) 1992-04-22
IT9021878V0 (en) 1990-10-03
IT220269Z2 (en) 1993-09-15

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