EP0627041B1 - Machine du type a rotor a vis - Google Patents

Machine du type a rotor a vis Download PDF

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Publication number
EP0627041B1
EP0627041B1 EP93904233A EP93904233A EP0627041B1 EP 0627041 B1 EP0627041 B1 EP 0627041B1 EP 93904233 A EP93904233 A EP 93904233A EP 93904233 A EP93904233 A EP 93904233A EP 0627041 B1 EP0627041 B1 EP 0627041B1
Authority
EP
European Patent Office
Prior art keywords
lobe
female
rotors
rotor
machine
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
EP93904233A
Other languages
German (de)
English (en)
Other versions
EP0627041A1 (fr
Inventor
Alan Bryson Riach
John Mcgruer
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.)
Sprintex Australasia Pty Ltd
Original Assignee
Sprintex Australasia Pty Ltd
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 Sprintex Australasia Pty Ltd filed Critical Sprintex Australasia Pty Ltd
Publication of EP0627041A1 publication Critical patent/EP0627041A1/fr
Application granted granted Critical
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Anticipated expiration legal-status Critical
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C1/00—Rotary-piston machines or engines
    • F01C1/08—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing
    • F01C1/082—Details specially related to intermeshing engagement type machines or engines
    • F01C1/084—Toothed wheels

Definitions

  • This invention relates to rotary positive displacement machines of the screw or helical rotors type, normally used as fluid compressors such as air compressors and to the rotors for use in such machines.
  • the invention relates to the dry type screw compressor where no lubricating oil passes through the working zones of the machine and the rotors are timed by the use of timing gears positioned outside the working chambers of the rotors which allow the rotors to rotate without coming into contact with each other.
  • the aforementioned dry type rotary machine includes a housing having at least one pair of intersecting bores therein. Inlet and outlet ports are provided at opposite ends of the casing bores. A rotor is mounted for rotation within each of the bores.
  • One of these rotors is of the male type which includes one or more helical lobes and intervening grooves which lie substantially outside the pitch circle thereof with the flanks of the lobes having a generally convex profile.
  • the other rotor is of the female type and formed so that it includes one or more helical lobes and intervening grooves which lie substantially inside the pitch circle thereof with the flanks of the grooves having a generally concave profile.
  • the lobes on the male rotor cooperate with the grooves on the female rotor and the walls of the casing to define chambers for the fluid. These chambers may be considered to be chevron shaped.
  • the chamber boundaries consist of the leading and trailing flanks of the male and female lobes and the bores in which the rotors rotate.
  • One leakage path is the sealing line between adjacent male and female rotor flanks as the rotors mesh.
  • the product of the length of this line and the required clearance forms a leakage path as described in US patent 2 622 787.
  • Another important leakage path is between the rotor tips and the casing bore, especially in the case of the slower rotating rotor, in which case there is a relatively long time during which leakage flow can occur.
  • the width of the rotor tips is an important factor as this defines the length of the path through which the gas must pass before leaking to an adjacent chamber. A long path provides an effective means of reducing the leakage.
  • a third major leakage path is the channel between the male and female rotors and the cusp of the intersecting rotor bores sometimes described as the blow hole or leakage triangle. This blowhole occurs at both cusps where the rotors mesh.
  • each rotor is substantially formed from a circular arc.
  • Such a profile illustrated in US patent 2 622 787 gives a short sealing line length, but results in a large blow hole.
  • Another commonly used profile is the asymmetric profile, also described in US patent 2 622 787.
  • one flank of each female rotor flute is defined as a circular arc or a section of an ellipse. The remaining female flank is generated by points near the outside of the meshing male flank. Both male flute flanks are generated by points on the female rotor.
  • This asymmetric profile has a large blowhole at the other cusp but this is not important if the machine is used as a simple compressor or expander where compression or expansion occurs on one side only.
  • This normally requires the female rotor to have a significant addendum, that is the outer diameter of the female rotor is significantly larger than the pitch circle, and that the flanks of both rotors have smooth curves to transmit the driving force.
  • the addendum of the female rotor is normally of convex curvature and is commonly formed by a radius linking the flank to the tip as shown in US patent 2 622 787 and GB patent 2 112 460. This radius increases the size of the blowhole and results in a rotor tip which is short in width and thus which has a short leakage path.
  • the provision of driving flanks also normally requires the male rotor to be rounded at the tip, typically having a radius linking the flanks to the tip, further increasing the size of the blowhole.
  • the compressor of GB-A-2 112 460 like that of US-A-2 622 787 has intermeshing male and female lobed rotors, and in this case the male lobe has an asymmetric transverse profile with flanks having varying centres of curvature while the flanks of the female lobe also define an asymmetric transverse profile with varying centres of curvature.
  • the male rotor lobe is described as having a curved outer portion joining the flank to the tip, the remainder of the male rotor flank being generated by points on the female rotor.
  • the said curved portion generates the majority of the female rotor flank except for a portion near the tip which is convex in nature and is normally constructed as a segment of an arc joining the flank to the tip. Because the majority of the rotor flanks are generated, the blowhole is reduced compared to other known profiles such as the circular profile described above.
  • a further objective is to reduce the leakage between the rotor tips and the bore by maximising the length of the leakage path across the tips.
  • the slower rotating rotor (usually the female) has a peripheral land on the lobes of relatively wide form providing a long leak path between the peripheral lands and the casing means.
  • the basic rotor profile is a combination of point and line generated and is symmetric in nature.
  • a screw compressor or pump 1 comprises intermeshing male and female rotors 2, 3 having helical lobes 4, 5 respectively, housed in a casing 6.
  • Each of the lobes 4, 5 has leading (4L, 5L) and trailing surfaces (4T, ST) respectively
  • the shafts of the rotors 2, 3 are carried by bearings 7, while a drive (not shown) is connectable to one of the shafts 8.
  • Gears 9, 10 serve for individual driving of the rotors 2, 3, as distinct from an arrangement where one of the rotors is driven directly from the other via lobe engagement. This enables the machine 1 to operate in a dry mode i.e. without lubricant in the rotors as there is no requirement for torque (force) transmission between the rotors, and this is beneficial for the particular uses intended for compressor (pump) machines in accordance with the present invention.
  • Figs 2 and 3 show the rotor profile preferred for the supercharger of an internal combustion engine.
  • the profile of the male lobe 4 is of sophisticated symmetric form, that is to say other than a simple semi-circular (symmetric) profile, symmetry being present about the mid-axis M-M and the profile curves having different centres of curvature.
  • the design of rotor profile can be categorised as one of the following:
  • the lobe profiles of the present machine 1 are obtained by a co-generation process, that is the profile shape of one lobe is produced by the line traced out by a point or ine on the other intermeshing lobe as it moves.
  • the portion RS is generated by the male tip portion SV is generated by point N; and VW is a straight line.
  • portion NP is generated by point V on rotor 3
  • portion PQ is generated by line VW on rotor 3
  • QT is generated by point W.
  • C MP and C FR are the pitch circles of the male and female rotors respectively, while C MO and C FO are the corresponding outside circles.
  • the portions VW on the opposed lobe flanks of the female rotor 3 diverge at the periphery of the rotor to facilitate rotor manufacture.
  • blow holes or leakage triangles which occur at the tone marked B in Fig 1: Fig 4 shows the detail to a larger scale looking in the axial direction of the machine.
  • the blow holes will be present at both the high pressure and low pressure sides of the machine, but with the machine operating as an ordinary gas compressor with a set operational direction leakage is critical only via one side (the high pressure side) and the size of the blow holes at the other side is not really critical.
  • a further feature of the profile is that the peripheral land 12 on at least one of the rotors 2, 3 can be relatively wide so forming a choks gap between the rotor and the casing 6 thereby mitigating against leakage via this path: in the profile of Fig 2 the peripheral land on the slower rotating female rotor is relatively wide.
  • the leakage between the rotor tips 12 and the bore of the casing 6 is reduced by the present invention.
  • the above machine 1 can be provided advantageously with a suitable variable area inlet port.

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

Claims (4)

  1. Machine volumétrique rotative, comprenant une paire de rotors (2, 3) pourvus de lobes à vis ou hélicoïdaux (4, 5) s'engrenant logés dans un moyen de carter (6); et des moyens d'entraínement (8, 9, 10) destinés à entraíner séparément les rotors (2, 3), dans laquelle un premier des rotors, le rotor mâle (2), présente un lobe (4) de profil transversal symétrique, avec des centres de courbure variables; et les profils des rotors (2, 3) sont produits à l'aide d'un processus de cogénération, une portion de racine (RS) du rotor femelle (3) entre des lobes étant générée par le sommet du lobe (4) du rotor mâle, et les surfaces arrière et avant de chaque lobe femelle (5) présentant une première portion (SV) jusqu'à un point de transition (V) de forme concave, caractérisée en ce qu'une portion finale (VW) jusqu'au sommet du lobe femelle est de forme droite, les portions finales (VW) des surfaces avant et arrière de chaque lobe femelle (5) divergeant l'une de l'autre dans la direction radialement extérieure.
  2. Machine selon la revendication 1, caractérisée en ce qu'un listel périphérique (12) sur les lobes (5) du rotor femelle (3) est de forme relativement large pour procurer un long chemin de fuite entre les listels périphériques (12) et le moyen de carter (6).
  3. Machine selon la revendication 1 ou 2, caractérisée en ce que le profil de base des rotors est une combinaison d'une génération par point et par ligne et est de nature symétrique.
  4. Machine selon la revendication 1, 2 ou 3, caractérisée en ce que ladite première portion (SV) des flancs (5L, 5T) des lobes femelle est générée par un coin de sommet (N) du lobe mâle (4), tandis que les flancs (4L, 4T) du lobe mâle (4) présentent une première portion (NP) du sommet mâle générée par ledit point de transition (V) du lobe femelle, une deuxième portion (PQ) générée par la ligne droite (VW) du lobe femelle, et une portion finale (QT) générée par le point de coin (W) du sommet du lobe femelle.
EP93904233A 1992-02-19 1993-02-19 Machine du type a rotor a vis Expired - Lifetime EP0627041B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB929203521A GB9203521D0 (en) 1992-02-19 1992-02-19 Screw rotors type machine
GB9203521 1992-02-19
PCT/GB1993/000349 WO1993017223A1 (fr) 1992-02-19 1993-02-19 Machine du type a rotor a vis

Publications (2)

Publication Number Publication Date
EP0627041A1 EP0627041A1 (fr) 1994-12-07
EP0627041B1 true EP0627041B1 (fr) 1999-09-29

Family

ID=10710675

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93904233A Expired - Lifetime EP0627041B1 (fr) 1992-02-19 1993-02-19 Machine du type a rotor a vis

Country Status (4)

Country Link
EP (1) EP0627041B1 (fr)
DE (1) DE69326606T2 (fr)
GB (1) GB9203521D0 (fr)
WO (1) WO1993017223A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7530217B2 (en) 2005-12-16 2009-05-12 General Electric Company Axial flow positive displacement gas generator with combustion extending into an expansion section
US7726115B2 (en) 2006-02-02 2010-06-01 General Electric Company Axial flow positive displacement worm compressor
US7854111B2 (en) 2008-03-07 2010-12-21 General Electric Company Axial flow positive displacement turbine
US8328542B2 (en) 2008-12-31 2012-12-11 General Electric Company Positive displacement rotary components having main and gate rotors with axial flow inlets and outlets
US8708643B2 (en) 2007-08-14 2014-04-29 General Electric Company Counter-rotatable fan gas turbine engine with axial flow positive displacement worm gas generator

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT454201A (fr) * 1947-07-16
US3289600A (en) * 1964-03-13 1966-12-06 Joseph E Whitfield Helically threaded rotors for screw type pumps, compressors and similar devices
SE312394B (fr) * 1965-05-10 1969-07-14 A Lysholm
GB1294210A (en) * 1970-09-29 1972-10-25 Le Ni I K I Khim Mash Improvements in or relating to meshing screw-rotor machines for compressible fluids
SE429783B (sv) * 1981-12-22 1983-09-26 Sullair Tech Ab Rotorer for en skruvrotormaskin

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7530217B2 (en) 2005-12-16 2009-05-12 General Electric Company Axial flow positive displacement gas generator with combustion extending into an expansion section
US7726115B2 (en) 2006-02-02 2010-06-01 General Electric Company Axial flow positive displacement worm compressor
US8708643B2 (en) 2007-08-14 2014-04-29 General Electric Company Counter-rotatable fan gas turbine engine with axial flow positive displacement worm gas generator
US7854111B2 (en) 2008-03-07 2010-12-21 General Electric Company Axial flow positive displacement turbine
US8328542B2 (en) 2008-12-31 2012-12-11 General Electric Company Positive displacement rotary components having main and gate rotors with axial flow inlets and outlets

Also Published As

Publication number Publication date
DE69326606D1 (de) 1999-11-04
EP0627041A1 (fr) 1994-12-07
DE69326606T2 (de) 2000-05-04
WO1993017223A1 (fr) 1993-09-02
GB9203521D0 (en) 1992-04-08

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