WO1991017345A1 - Compresseur a vis rotative a elements d'equilibrage de poussee - Google Patents

Compresseur a vis rotative a elements d'equilibrage de poussee Download PDF

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Publication number
WO1991017345A1
WO1991017345A1 PCT/SE1991/000309 SE9100309W WO9117345A1 WO 1991017345 A1 WO1991017345 A1 WO 1991017345A1 SE 9100309 W SE9100309 W SE 9100309W WO 9117345 A1 WO9117345 A1 WO 9117345A1
Authority
WO
WIPO (PCT)
Prior art keywords
capacity
compressor
slide valve
thrust balancing
orifice
Prior art date
Application number
PCT/SE1991/000309
Other languages
English (en)
Inventor
Frits SÖDERLUND
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 WO1991017345A1 publication Critical patent/WO1991017345A1/fr

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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
    • F04C29/0021—Systems for the equilibration of forces acting on the pump

Definitions

  • the present invention relates to a rotary screw compressor having a pair of intermeshing rotors in a work ⁇ ing space and axial slide means regulating the capacity of the compressor in a valve boring facing the working space and extending axially along the same, at least one of the rotors being provided with hydraulic or pneumatic thrust balancing means including a first pressure chamber facing a pressure surface, a supply channel for the supply of pressure fluid to said first pressure chamber and a drainage channel connected to said supply channel, said drainage channel being controlled by a cut-off valve having an open position connecting said drainage channel to a low pressure source and a closed position.
  • a compressor having such thrust balancing means is known from US 3,388,854.
  • the cut-off valve is governed by means sensing the outlet or interstage pressure of the compressor.
  • This load is taken up by thrust bearings.
  • the compressor can be provided with a hydraulic thrust balancing device acting on the rotors in a direction contrary to the direction of the axial gas forces.
  • the thrust balancing fore? required at full capacity will exceed the gas forces when running at reduced capacity. Therefore the thrust balancing force should be in-activated or reduced when running at lower capacity in order to avoid over- compensation of the axial load.
  • the object of the present invention is to find a simple and reliable way to adapt the thrust balancing force to the capacity of the compressor.
  • the position of the slide valve means governs said cut-off valve so that the cut-off valve is open when the slide valve means are in a position corresponding to a capacity at or below a certain level and is closed when the slide valve means are in a position corresponding to a capacity above said level.
  • Figure 1 is a partial section through a compressor according to a first embodiment of the invention.
  • Figure 2 is a section similar to that of figure 2 but according to a second embodiment of the invention.
  • the upper part is a longitudinal section through one of the rotors 12 of a rotary screw compressor according to the invention.
  • the lower part of the figure shows the slide valve means 14 regulating the capacity and the internal volume ratio of the compressor.
  • the screw rotor 12 intermesh with a second screw rotor (not shown) to form chevron-shaped compression chambers in a working space 13 limited by a low pressure end wall 15, a high pressure end wall 17, a barrel wall 19 and slide valve means 14.
  • the working space 13 has in a transversal section the shape of two intersecting borings formed by the barrel wall 19 and those surfaces of the slide valve means 14 which face the working space 13.
  • the slide valve means 14 include a slide stop member 32 and a slide valve member 34.
  • the slide stop member 32 and the slide valve member 34 can independently of each other be displaced axially in an axial boring 16 intersecting the working space 13 and are guided by the wall 42 of the boring 16.
  • the slide valve means 14 are in a position representing full capacity. For attaining reduced capacity the slide stop member 32 is moved leftwards in the figure or the slide valve member 34 is moved rightwards.
  • Each rotor 12 is provided with shaft journals 21, 23 for the journalling of the rotors.
  • the shaft journal 23 at the high pressure end is journalled in journal roller bearing 25, thrust ball bearings 27, 29, and thrust balancing bearing 31.
  • Hydraulic thrust balancing means 18 act on the thrust balancing bearing 31. These means include a pressure chamber 20 facing a pressure surface 22 on an actuating member 33 abutting the outer ring 35 of the thrust balancing bearing 31.
  • Oil under pressure is supplied to the pressure chamber 20 through a supply channel 24. From the supply channel 24 a drainage channel 26 leads to an orifice 30 in the wall 42 of the valve boring 16.
  • the oil supplied through the channel 24 can preferably be pressurized by the outlet pressure of the compressor.
  • a liquid is used as pressure medium in the described embodiment it should be understood that gaseous pressure medium can be used as well.
  • the compressed gas exerts an axial load on eadch rotor 12 in a direction from the high pressure end to the low pressure end of the compressor, i.e. leftwards in the figure as indicated by the arrow F.
  • a force can be applied to the outer ring 35 of the thrust balancing bearing 31, which transmits this force to the rotor 12.
  • the thrust balancing force is directed contrary to the axial gas forces, i.e. rightwards in the figure. Thereby the axial load on the thrust ball bearings 27, 29 will be reduced so that a longer running life of these bearings is attained.
  • the compressor When the compressor is running at reduced capacity, the axial gas forces will be smaller. There is therefore no longer any need to balance these forces when the capacity is below a certain level. In contrary the thrust balancing force under such condition might over-compensate the axial gas forces so that the resulting force on the rotor 12 momentary can be directed rightwards with the risk that the rotor 12 contacts the high pressure end wall 17 as a consequence.
  • the compressor is provided with means to in-activate the thrust balancing means 18 when running at a capacity below a certain level. At reduced capacity the slide stop member 32 and the slide valve member 34 are spaced apart.
  • the orifice 30 communicates with the interspace through the recess 40 in the front end surface 36 of the slide stop member 32.
  • the orifice 30 and the low pressure port 44 When communication between the orifice 30 and the low pressure port 44 is open, oil supplied to the pressure chamber 20 through the supply channel 24 will be drained to the low pressure port 44 through the drainage channel 26, the orifice 30, the interspace between the slide stop member 32 and the slide valve member 34 and through the working space 13 of the compressor. Thereby the pressure acting on the pressure surface 22 is relieved and as a consequence the thrust balancing force is in-activated.
  • the axial location of the orifice 30 can easily be calculated in order to correspond to the capacity condition where there is no need for thrust balancing.
  • the position of the rear end surface 38 of the slide valve member 34 determines the capacity. The more to the right this end surface is positioned in the figure, the lower is the capacity.
  • the orifice thus is located adjacent the rear end surface 38 of the slide valve member 34 to the left side (in the figure) thereof when the slide valve member 34 is in a position representing the capacity at or below which the thrust balancing means 18 shall be in-activated. In typical cases this lies somewhere in the range from 60 % to 85 % , normally about 75 % of full capacity.
  • the thrust balancing force can be adapted to the capacity of the compressor in a very simple and reliable way. No extra means for governing this is required since it is governed directly by the capacity regulating means.
  • Figure 2 illustrates in a view similar to that of figure 1 an alternative embodiment of the invention, in which there are provided thrust balancing means at both ends of the compressor.
  • the thrust balancing means 118 at the high pressure side are of similar construction as those 18 of figure 1.
  • the supply channel 124 has no drainage channel so that these thrust balancing means 118 are active under all working conditions.
  • the thrust balancing means 58 at the low pressure end have a pressure chamber 50 facing the end surface 52 of the shaft journal 21. The thrust balancing force thus acts directly on the rotor when oil under pressure is supplied to the pressure chamber 50 through the supply channel 54.
  • the shaft journal 21 is journalled in a roller bearing 46, and there is a seal 48 between the roller bearing 46 and the pressure chamber 50.
  • a drainage channel 56 connects the supply channel 54 to the orifice 30 in the wall 42 of the valve boring.
  • the pressure in the pressure chamber 50 is relieved since the drainage channel undere such conditions communicate with the low pressure prot 44 through the interspace between the slide stop member 32 and the slide valve member 34 and through the working space 13 of the compressor. This is accomplished in the same manner as described in relation to f gure 1.
  • both the thrust balancing means 58 and 118 are active at full capacity, whereas at reduced capacity the thrust balancing means 118 at the high pressure end are active and the thrust balancing means 58 at the low pressure end are in-active. Through this embodiment of the invention it is thus possible to maintain a certain thrust balancing force also at reduced capacity but at a lower level corresponding to the smaller axial gas forces.
  • a piston having a larger pressure surface can be fixed to the end of the shaft journal. It is possible also to provide the thrust balancing means 118 at the high pressure end with a drainage channel connected to a second orifice in the wall of the valve boring, through which this thrust balancing means can be in-activated at a still lower capacity level.

Landscapes

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

Abstract

Dans un compresseur à vis rotative comportant des éléments de régulation de capacité (14), les efforts de gaz axiaux sur les rotors (12) sont équilibrés par des éléments hydrauliques d'équilibrage de poussée (18). Lorsque le compresseur fonctionne à capacité réduite en-dessous d'un certain niveau, la force d'équilibrage de poussée est rendue inactive. Ceci est effectué par l'évacuation de l'huile de pression alimentée aux éléments d'équilibrage de poussée (18) par l'intermédiaire de l'ouverture d'une soupape de fermeture (28) qui commande un canal d'évacuation (26) relié au canal d'alimentation d'huile (24). Selon l'invention, la soupape de fermeture (28) est directement commandée par les éléments de régulation de capacité (14) de sorte que lorsque ces éléments se trouvent dans une position indiquant une capacité en-dessous d'un certain niveau, normalement à environ 75 % de la capacité totale, le canal d'évacuation (26) est relié à une source de basse pression. Les éléments de régulation de capacité peuvent de préférence fonctionner comme une soupape de fermeture qui, lorsqu'elle est en position ouverte, relie le canal d'évacuation (26) à l'ouverture de basse pression (44) du compresseur par l'intermédiaire de l'espace de travail du compresseur (13).
PCT/SE1991/000309 1990-05-08 1991-04-30 Compresseur a vis rotative a elements d'equilibrage de poussee WO1991017345A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9001640-3 1990-05-08
SE9001640A SE466166B (sv) 1990-05-08 1990-05-08 Skruvkompressor med axialbalanseringsorgan

Publications (1)

Publication Number Publication Date
WO1991017345A1 true WO1991017345A1 (fr) 1991-11-14

Family

ID=20379409

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1991/000309 WO1991017345A1 (fr) 1990-05-08 1991-04-30 Compresseur a vis rotative a elements d'equilibrage de poussee

Country Status (2)

Country Link
SE (1) SE466166B (fr)
WO (1) WO1991017345A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5411388A (en) * 1991-11-13 1995-05-02 Svenska Rotor Maskiner Ab Rotary screw machine with thrust balanced bearings
US9022760B2 (en) 2011-11-02 2015-05-05 Trane International Inc. High pressure seal vent
US20210079953A1 (en) * 2019-09-18 2021-03-18 Aktiebolaget Skf Rolling bearing, particularly hybrid rolling bearing for refrigerant compressor
US11473623B2 (en) 2019-11-25 2022-10-18 Aktiebolaget Skf Bearing assembly

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3388854A (en) * 1966-06-23 1968-06-18 Atlas Copco Ab Thrust balancing in rotary machines
US4964790A (en) * 1989-10-10 1990-10-23 Sundstrand Corporation Automatic regulation of balancing pressure in a screw compressor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3388854A (en) * 1966-06-23 1968-06-18 Atlas Copco Ab Thrust balancing in rotary machines
US4964790A (en) * 1989-10-10 1990-10-23 Sundstrand Corporation Automatic regulation of balancing pressure in a screw compressor

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5411388A (en) * 1991-11-13 1995-05-02 Svenska Rotor Maskiner Ab Rotary screw machine with thrust balanced bearings
US9022760B2 (en) 2011-11-02 2015-05-05 Trane International Inc. High pressure seal vent
US20210079953A1 (en) * 2019-09-18 2021-03-18 Aktiebolaget Skf Rolling bearing, particularly hybrid rolling bearing for refrigerant compressor
US11067129B2 (en) * 2019-09-18 2021-07-20 Aktiebolaget Skf Rolling bearing for refrigerant compressor
US11473623B2 (en) 2019-11-25 2022-10-18 Aktiebolaget Skf Bearing assembly

Also Published As

Publication number Publication date
SE9001640L (sv) 1991-11-09
SE9001640D0 (sv) 1990-05-08
SE466166B (sv) 1992-01-07

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