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US3904322A - Screw compressor - Google Patents

Screw compressor Download PDF

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Publication number
US3904322A
US3904322A US374500A US37450073A US3904322A US 3904322 A US3904322 A US 3904322A US 374500 A US374500 A US 374500A US 37450073 A US37450073 A US 37450073A US 3904322 A US3904322 A US 3904322A
Authority
US
United States
Prior art keywords
slide gate
compressor
control valve
working chamber
capacity control
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 - Lifetime
Application number
US374500A
Other languages
English (en)
Inventor
Rolf Axelsson
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.)
Stal Refrigeration AB
Original Assignee
Stal Refrigeration 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 Stal Refrigeration AB filed Critical Stal Refrigeration AB
Application granted granted Critical
Publication of US3904322A publication Critical patent/US3904322A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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

  • a section of the cylindrical housing between the rotors is constructed as an axially movable slide gate, the outer surface of which is cylindrically convex and rests in a corresponding, trough-like recess in the housing, this recess extending at its bottom into an opening in the compressor housing which is exposed when the slide gate is displaced toward the outlet end of the compressor.
  • the slidegate comprises a body defined by two concave and one convex cylindrical surfaces, which, in prior art compressors, is joumalled primarily in a drilling in the rotor housing corresponding to the convex cylindrical surface of the slide gate.
  • the slide gate therefore is required to extend more than 180 (usually about 200") of the total cylinder surface, and as a consequence, becomes rather large and clumsy.
  • rotation of the slide gate in the housing drilling must be prevented by the use of guide bosses or the like, and replacement of a slide gate in an already assembled known compressor is troublesome and difficult.
  • the present invention has as its primary object the provision of a slide gate for a screw compressor which is considerably simplified, less bulky, and much more easily exchanged or replaced than those now in use.
  • the novel slide gate is further guided by an opening in the outlet end closure of the compressor corresponding to the profile of the slide gate and by a piston rod attached to the slide gate and slidably journalled in the rotor housing.
  • This guidance system makes it possible for the slide gate to be much slimmer and less bulky.
  • the extent of the convex cylindrical surface of the slide gate may be kept to about 60, as contrasted to the more than 180 of the prior art.
  • the respective arcs should extend along a curvature of less than 90.
  • slide gate of this invention can be more simply fitted and replaced in the compressor otherwise already assembled.
  • FIG. 1 is a longitudinal section through a screw compressor constructed according to this invention, taken along line AA of FIG. 2;
  • FIG. 2 is a view of the compressor as seen from its outlet end
  • FIGS. 3a and 3b are, respectively, a top plan view and an end view of the slide gate itself.
  • FIG. 1 shows the compressor housing, consisting of cylindrical body 1 and the end closures 2 and 3.
  • the two helical rotors which rotate within the compressor housing have been omitted for the sake of clarity, but their construction is known and described, for example, in US. Pat. No. 3,283,996.
  • End closure 2 forms the inlet side of the compressor and contains inlet opening 4; end closure 3 forms the outlet side, with outlet opening 5.
  • a flange 6 is clamped to end closure 3 for sealing purposes and for journallin g of the rotors (not shown).
  • slide gate 8 rests slidably in a trough-like recess in the compressor housing 1.
  • the shape of slide gate 8 is clearly illustrated in FIG. 2 where it can be seen readily that its profile is defined at the top of two concave cylindrical surfaces, while its lower side is a convex cylindrical surface conforming to the trough-like recess in housing.
  • Slide gate 8 is attached by spring snap ring 10 to piston rod 9, the righthand end of which is slidably journalled in a drilling in housing 1. Further guidance of slide gate 8 is provided in outlet opening 5 of end closure 3, as shown in FIG. 2.
  • Outlet opening 5 has an upper portion lying within the periphery of the two rotors which is conventionally shaped in approximate agreement with the grooves in the rotors. Below this section the edge of opening 5 is defined by two machined bosses 11,12 which fit exactly the upper surfaces of slide gate 8, which is thus guided at its top by bosses 11,12, at its bottom by the bottom 13 of the trough-like recess, and at its righthand end by piston rod 9. Bosses 11,12 also prevent axial rotation of slide gate 8 in either direction.
  • slide gate 8 is displaceable and slidable axially, and in FIG. 1 is shown in its lefthand open position, exposing opening 14 in the bottom 13 of the recess in housing 1.
  • the position of slide gate 8 is controlled by the piston 15 in cylinder 16, the pressure from piston 15 being transmitted to piston rod 9 through connecting rod 17 and perforated pressure plate 18 mounted on rod 17.
  • the slide gate 8 and thus the compressor unit function in the following way: in the position shown in FIG. 1, gas passes from the intake 4 through the channels formed by the rotors, after which most of the gas passes through opening 14, the holes in pressure plate 18, and the return channel 19 back to inlet 4. Only a small quantity of gas will be compressed in the active part of the rotor grooves, i.e., the quantity of gas opposite the part of slide gate 8 which is within housing 1. This means that the lefthand end of slide gate 8 is influenced by the outlet pressure while its righthand is influenced by the intake pressure. During operation, therefore, slide gate 8 is urged by a resultant pressure to the right which endeavors to close opening 14. This pressure is counteracted by pressure from piston 15.
  • cylinder 16 is connected to the outlet and inlet side of the compressor by conduits 20 and 21 respectively, (shown diagrammatically), each provided with a shut-off valve. As shown in FIG. 1, cylinder 16 is opcratively connected to outlet opening 5 (the valve in conduit 20 is open) so that pressure in cylinder 16 applied via piston 15, connecting rod 17, pressure plate 18 and piston rod 9 overcome the previously mentioned ambient pressure on slide gate 8. It is clear that in order to accomplish this, piston must have a minimum area relative to the cross-sectional area of slide gate 8. Piston 15 should have a cross-sectional area at least double that of slide gate 8.
  • FIG. 1 corresponds to the lowest capacity of the compressor since opening 14 is completely unobstructed
  • the capacity of the compressor is increased by shutting off conduit and opening conduit 21 so that cylinder 16 is connected to inlet port 4.
  • the pressure on piston 15 thereby disappears and pressure from the outlet side forces slide gate 8 to the right so that opening 14 is throttled.
  • Full compressor capacity is attained when slide gate 8 is in its rightmost position, when cylindrical housing 1 is completely enclosed and uninterrupted and compression occurs along the entire length of the rotors.
  • valves in conduits 20 and 21 are preferably operated by a pressure regulator (not shown) controlled by the pressure from the outlet side of the compressor.
  • a pressure regulator not shown
  • Such regulator control is well known, however, and does not fall within the scope of the present invention.
  • slide gate 8 permits slide gate 8 to be replaced easily by loosening spring snap ring 10, which is of importance for the following reason: the shape of slide gate 8 is shown most clearly in FIGS. 3a and 3b and it can be seen that the lefthand end of slide gate 8 is cut or bevelled on the upper side.
  • the desired volume ratio can be achieved: strong bevelling giving a large outflow opening from the slide gate and thus low volume ratio, i.e., moderate outlet pressure, while slight bevelling will give a large volume ratio and thus considerable outflow pressure.
  • a slide gate comprising a portion of the wall of said working chamber and being axially displaceable to regulate an opening for venting working fluid from the bottom of the working chamber;
  • said slide gate in cross section defining a triangular profile the base of which describes a convex shallow arc with its center located on a line of symmetry between the two helical screws and the two sides thereof describing two shallow concave arcs conforming to the peripheral contour of the helical screws, each of said ares defining a curvature of less than to form a substantially flat triangular member;
  • said slide gate being guided in a recess in said working chamber which recess has a profile corresponding to the profile of said slide gate;
  • a piston rod connected to said slide gate and slidably journalled in said working chamber for further guiding the slide gate.
  • a capacity control valve according to claim 1, wherein the movement of the slide gate is controlled by a valve actuating piston movable in a pressure fluid cylinder, said piston and said cylinder being located at the inlet end of the compressor.
  • a capacity control valve according to claim 3, wherein said valve actuating piston and said cylinder are positioned eccentrically with respect to said piston rod of the slide gate and located adjacent the inlet wall of the working chamber.
  • a capacity control valve wherein the displacement of the slide gate is accomplished by operatively connecting said pressure fluid cylinder to the outlet end and the inlet end, respectively, of the working chamber.
  • a capacity control valve according to claim 3, wherein the free end of the slide gate projects into the outlet portion of the compressor and is actuated by the surrounding pressure, while the free end of said piston rod of the slide gate rests freely against said valve actuating piston.
  • a capacity control valve according to claim 6, wherein the cross-sectional area of said valve actuating piston in said cylinder is at least double the crosssectional area of the slide gate.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Rotary-Type Compressors (AREA)
US374500A 1972-06-30 1973-06-28 Screw compressor Expired - Lifetime US3904322A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE08645/72A SE366375B (da) 1972-06-30 1972-06-30

Publications (1)

Publication Number Publication Date
US3904322A true US3904322A (en) 1975-09-09

Family

ID=20274665

Family Applications (1)

Application Number Title Priority Date Filing Date
US374500A Expired - Lifetime US3904322A (en) 1972-06-30 1973-06-28 Screw compressor

Country Status (6)

Country Link
US (1) US3904322A (da)
JP (1) JPS5412641B2 (da)
DE (1) DE2331830C2 (da)
GB (1) GB1418069A (da)
SE (1) SE366375B (da)
SU (1) SU880260A3 (da)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4579513A (en) * 1984-03-29 1986-04-01 Bernard Zimmern Positive displacement screw machine with separation wall attached to slide valve
US4909716A (en) * 1988-10-19 1990-03-20 Dunham-Bush Screw step drive internal volume ratio varying system for helical screw rotary compressor
US4913634A (en) * 1986-07-01 1990-04-03 Hitachi, Ltd. Screw compressor with slide valve movement preventing structure
US7878782B2 (en) 2005-12-12 2011-02-01 Johnson Controls Denmark Aps Screw compressor

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK97284A (da) * 1984-02-24 1984-03-05 Sabroe & Co As Skruekompressor med glidere til regulering af henholdsvis kapaciteten og volumenforholdet
GB2173257B (en) * 1984-03-29 1988-10-05 Bernard Zimmern A positive displacement screw machine
GB8528211D0 (en) * 1985-11-15 1985-12-18 Svenska Rotor Maskiner Ab Screw compressor
SE461927B (sv) * 1987-10-15 1990-04-09 Svenska Rotor Maskiner Ab Roterande deplacementskompressor med anordning foer reglering av dess inre volymfoerhaallande
SE461052B (sv) * 1988-04-25 1989-12-18 Svenska Rotor Maskiner Ab Lyftventil vid en skruvrotormaskin

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3088659A (en) * 1960-06-17 1963-05-07 Svenska Rotor Maskiner Ab Means for regulating helical rotary piston engines
US3314597A (en) * 1964-03-20 1967-04-18 Svenska Rotor Maskiner Ab Screw compressor
US3432089A (en) * 1965-10-12 1969-03-11 Svenska Rotor Maskiner Ab Screw rotor machine for an elastic working medium
US3738780A (en) * 1971-11-05 1973-06-12 Gardner Denver Co Capacity control valve for screw compressor
US3756753A (en) * 1970-07-16 1973-09-04 Svenska Rotor Maskiner Ab Two stage screw rotor machines

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE576047A (fr) * 1958-02-27 1959-08-24 Svenska Rotor Maskiner Ab Machine rotative à compression ou detente d'un fluide, et ses applications notamment à un refrigérateur
GB959831A (en) * 1959-06-04 1964-06-03 Svenska Rotor Maskiner Ab Improvements in or relating to screw rotor machines
FR1566954A (da) * 1968-05-22 1969-05-09

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3088659A (en) * 1960-06-17 1963-05-07 Svenska Rotor Maskiner Ab Means for regulating helical rotary piston engines
US3314597A (en) * 1964-03-20 1967-04-18 Svenska Rotor Maskiner Ab Screw compressor
US3432089A (en) * 1965-10-12 1969-03-11 Svenska Rotor Maskiner Ab Screw rotor machine for an elastic working medium
US3756753A (en) * 1970-07-16 1973-09-04 Svenska Rotor Maskiner Ab Two stage screw rotor machines
US3738780A (en) * 1971-11-05 1973-06-12 Gardner Denver Co Capacity control valve for screw compressor

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4579513A (en) * 1984-03-29 1986-04-01 Bernard Zimmern Positive displacement screw machine with separation wall attached to slide valve
US4913634A (en) * 1986-07-01 1990-04-03 Hitachi, Ltd. Screw compressor with slide valve movement preventing structure
US4909716A (en) * 1988-10-19 1990-03-20 Dunham-Bush Screw step drive internal volume ratio varying system for helical screw rotary compressor
US7878782B2 (en) 2005-12-12 2011-02-01 Johnson Controls Denmark Aps Screw compressor

Also Published As

Publication number Publication date
JPS5412641B2 (da) 1979-05-24
SE366375B (da) 1974-04-22
SU880260A3 (ru) 1981-11-07
DE2331830A1 (de) 1974-01-17
JPS4951614A (da) 1974-05-20
GB1418069A (en) 1975-12-17
DE2331830C2 (de) 1985-08-01

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