WO2011004342A2 - Rotors pour machine rotative à vis - Google Patents

Rotors pour machine rotative à vis Download PDF

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Publication number
WO2011004342A2
WO2011004342A2 PCT/IB2010/053135 IB2010053135W WO2011004342A2 WO 2011004342 A2 WO2011004342 A2 WO 2011004342A2 IB 2010053135 W IB2010053135 W IB 2010053135W WO 2011004342 A2 WO2011004342 A2 WO 2011004342A2
Authority
WO
WIPO (PCT)
Prior art keywords
rotor
rotors
female rotor
threads
rotors according
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.)
Ceased
Application number
PCT/IB2010/053135
Other languages
English (en)
Other versions
WO2011004342A3 (fr
Inventor
Mario Antonio Morselli
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.)
BORA Srl
Original Assignee
BORA Srl
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 BORA Srl filed Critical BORA Srl
Publication of WO2011004342A2 publication Critical patent/WO2011004342A2/fr
Publication of WO2011004342A3 publication Critical patent/WO2011004342A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/082—Details specially related to intermeshing engagement type pumps
    • F04C18/084—Toothed wheels
    • 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

  • the present invention relates to the rotary screw machine sector.
  • a typical, although non-limiting, example of a rotary screw machine is the screw compressor.
  • Rotary screw machines can also be used as vacuum pumps or as motors.
  • the invention has been developed with particular regard to mating rotors capable of rotating about parallel axes inside a working space within a rotary screw machine.
  • the rotors have a series of threads that are wound in a helical manner with respect to the axis of rotation of the rotors and that have, in a transverse section relative to the axis of rotation, characteristic profiles.
  • the profile of the threads of the screws formed on the two rotors is different for the two rotors.
  • one of the two rotors has a profile with a series of generally convex ridges, each constituting a screw thread, which engage in corresponding generally concave grooves formed on the other rotor.
  • the object of the present invention is to overcome the drawbacks of the prior art by providing two mating rotors for a rotary screw machine that are efficient and have a good mating coupling and therefore a good seal.
  • Another object of the invention is to propose two mating rotors that can be mounted easily and simply in a rotary screw machine, that are simple and inexpensive to produce, and that are nevertheless highly efficient.
  • Another object of the invention is to provide two mating rotors that are simple and inexpensive to manufacture in order to produce a rotary screw machine that can operate both as a vacuum pump and as a compressor or motor without significant modifications being required.
  • the invention relates to two mating rotors defined in the claims below.
  • the invention relates also to a rotary screw machine using the above-mentioned rotors.
  • the rotors of the present invention preferably have a number of threads equal to three or four for the male rotor, and correspondingly equal to six or seven for the female rotor.
  • the two rotors with asymmetrical profiles according to the present invention can be manufactured so as to have a nominally identical outer diameter, for greater simplicity of machining.
  • the teeth of the female rotor have an end area that is substantially free of sharp edges or very small radii of curvature, with the consequent absence of excessively small concave radii of curvature in the male rotor, in areas that otherwise would be difficult to machine. Furthermore, this characteristic contributes to the general object of improving mating, with the resulting advantages as regards sealing.
  • the ends of the teeth of the female rotor have a completely or almost completely rounded shape, with the complete or almost complete elimination of the portion of outer cylindrical profile of the prior art. This results in better coupling on mating and therefore improves sealing and also presents less of an obstacle to filling.
  • the profile of the female rotor teeth is "finger-shaped" with a clear narrowing in a substantially intermediate area between the end and bottom of the tooth, that is to say, a clear enlargement of the outermost area of the female rotor tooth.
  • the narrowing of the intermediate area of the female rotor tooth is in the order of 50%.
  • both flanks of the profile of each tooth of the female rotor enable a tangent to be drawn from the centre of the rotor. Furthermore, in relation to this tangent, they show a marked "dip" in their profile, that is, a pronounced concavity. This aspect also helps to improve coupling on mating, which greatly improves the seal.
  • a pair of rotors 10, 11 is intended for use in a rotary screw machine, for example a compressor or vacuum pump, of a type generally known and therefore not described in further detail below.
  • the rotors 10, 11 have respective central cores 12, 13 which, at the end of the rotors, extend to form the rotation shafts of the screws, supported by respective bearings in the box or casing of the rotary screw machine.
  • the rotors 10, 11 can be drilled through to house respective shafts splined to them.
  • the threads of the screws of the rotors 10, 11 extend helically along the height of the rotors, and in section they appear as shown in the drawing.
  • male rotors with three or four threads are preferable, although the production of male rotors with a different number of threads is not excluded from the scope of the present invention.
  • Each ridge 14 has a tip 15, or point of maximum radius r10, from which extend, on opposite sides, a right-hand flank 16 and a left-hand flank 17.
  • the right-hand flank 16 and the left-hand flank 17 have different profiles, which are asymmetrical in relation to the radius
  • the profile of the male rotor 10 has channel areas 18 of very small diameter.
  • the female rotor 11 has a series of grooves 18 mating with the ridges 14 of the male rotor 10. Interposed between the grooves 18 are ribs or teeth 19 matching the section of the threads of the female screw along a transverse plane in relation to the axis of rotation O11 of the female rotor 11.
  • the preferred, although non-limiting, couplings of the present invention are a male rotor having three threads with a female rotor having six threads, or a male rotor having four threads with a female rotor having seven threads.
  • Each rib 19 of the female rotor 11 has a substantially rounded tip 20, or point of maximum radius r11 , from which extend, on opposite sides, a right-hand flank 21 and a left-hand flank 22, mating with the right-hand 16 and left-hand 17 flanks, respectively, of the male rotor 10.
  • the tips 20 of the ribs 19 define a maximum outer circle C11 of a diameter equal to the diameter d10 of the male rotor 10, and preferably have no sharp edges or significant cylindrical portions.
  • the right-hand flank 21 and the left-hand flank 22 of the female rotor also have different profiles, which are asymmetrical in relation to the radius r11 passing through the tip 20 of each rib 19.
  • the profiles of the rotors achieve good efficiency if part of the right-hand flank 16 and of the left-hand flank 17 of the male rotor 10 each have a portion of the arc of a circle, and the two portions of arcs of a circle are of an appreciably different size as regards radius, even though they are tangent: the two portions of the arc of a circle describe a part of the right-hand flank 16 and a part of the left-hand flank 17 respectively.
  • the profiles are particularly efficient if the common tangent of the two portions of arcs of a circle that describe part of the profile of the right-hand flank 16 and part of the profile of the left-hand flank 17, respectively, of the male rotor 10 is perpendicular to a straight line (r10 in the drawing) passing through the centre of the rotor O10 and the point common to the two portions of circumference, that is, the tip 15 of the ridge 14.
  • Mating rotors were deemed to be particularly advantageous where the profile of one ridge 14 of the male rotor 10 is defined by a spline function passing through a plurality of nodal points having pre-established co-ordinates, with a tolerance of ⁇ 1/15, more preferably ⁇ 1/20, and even more preferably ⁇ 1/30 of the profile, that is, the difference between the maximum radius and the minimum radius of the theoretical profiles.
  • the nodal points are defined by a pair of values ⁇ X', Y' ⁇ expressed in a system of Cartesian co-ordinates having their origin in the centre O10 of the male rotor 10. Similar considerations apply to the mating female rotor.
  • the tolerance is measured in a direction perpendicular to the theoretical profile. It is particularly easy to assess the tolerance by describing for each nodal point a circle with a radius equal to the tolerance: the succession of circles permits an immediate understanding of whether a profile falls within the claimed band.
  • the origins of the system of X, Y coordinates are the lines of the axis of rotation of the rotors 10 and 11 on a plane perpendicular to the said axes, which coincide with the centres 010 and 011 of the circles C10 and C11 of maximum diameter of the male 10 and female 11 rotors.
  • the spline function used describes the arcs of circumference of the male rotor as defined above with a reproduction error such as to have no influence on the production tolerance.
  • spline function refers generally to any spline function which does not introduce errors, or to a smoothing spline with a smoothing parameter that is sufficiently small not to introduce significant errors in relation to the nodal points.
  • the spline function adopted is a natural cubic spline function, that is, a third-degree interpolating natural spline function.
  • the co-ordinates of the nodal points of the male rotor are homothetic to the pairs of values ⁇ X,Y ⁇ in the list contained in Table 1 below.
  • the profile of the female rotor 11 is determined by the condition of mating, once the number of threads has been defined.
  • small modifications dictated by experience are made to ensure the correct operating clearance and permit differential thermal expansion, although these small modifications do not influence the fundamental principle of the present invention.
  • the nodal points through which, as also described above for the male rotor 10 and with the same tolerances, the profile of a rib 19 of the female rotor 11 is defined are defined by a pair of values ⁇ X',Y' ⁇ expressed in a system of Cartesian co-ordinates having their origin in the centre 011 of the female rotor 11 , and are homothetic to the pairs of values ⁇ X,Y ⁇ in the list contained in Table 2 below.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Rotary Pumps (AREA)

Abstract

L’invention concerne une machine rotative à vis, telle qu’un compresseur à vis, une pompe à vide ou un moteur, comprenant des rotors homologues présentant des profils asymétriques et le même diamètre extérieur. De préférence, l’extrémité de la dent de rotor mâle présente, du point de vue du rayon maximum, sur les deux flancs, deux parties d’arc d’un cercle de dimension sensiblement différentes en ce qui concerne le rayon mais tangentes, décrivant une partie du flanc gauche et une partie du flanc droit respectivement. Le rotor femelle présente les éléments homologues respectifs dans la zone correspondante du fond de la dent. De préférence, le rotor mâle présente trois ou quatre filets, tandis que le rotor femelle présente de préférence six ou sept filets, et idéalement le rotor mâle présente quatre filets et le rotor femelle présente sept filets. Des lignes peuvent être tracées du centre du rotor femelle de manière tangente aux deux flancs de la même dent.
PCT/IB2010/053135 2009-07-09 2010-07-08 Rotors pour machine rotative à vis Ceased WO2011004342A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITBO2009A000442 2009-07-09
ITBO2009A000442A IT1395017B1 (it) 2009-07-09 2009-07-09 Rotori per una macchina rotativa a vite

Publications (2)

Publication Number Publication Date
WO2011004342A2 true WO2011004342A2 (fr) 2011-01-13
WO2011004342A3 WO2011004342A3 (fr) 2011-05-12

Family

ID=42109818

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2010/053135 Ceased WO2011004342A2 (fr) 2009-07-09 2010-07-08 Rotors pour machine rotative à vis

Country Status (2)

Country Link
IT (1) IT1395017B1 (fr)
WO (1) WO2011004342A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105257537A (zh) * 2015-11-03 2016-01-20 晗森机械（上海）有限公司 一种三齿螺杆压缩机的转子端面齿型

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1388376A (en) 1972-07-14 1975-03-26 Linde Ag Meshing screw pumps

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4508496A (en) * 1984-01-16 1985-04-02 Ingersoll-Rand Co. Rotary, positive-displacement machine, of the helical-rotor type, and rotors therefor
JPS60212684A (ja) * 1984-04-07 1985-10-24 Hokuetsu Kogyo Co Ltd スクリユ・ロ−タ
US4671750A (en) * 1986-07-10 1987-06-09 Kabushiki Kaisha Kobe Seiko Sho Screw rotor mechanism with specific tooth profile
JP2703323B2 (ja) * 1989-03-24 1998-01-26 株式会社神戸製鋼所 スクリュ式ポンプ装置用スクリュロータ
KR100425414B1 (ko) * 2002-01-25 2004-04-08 이 재 영 스크류 압축기용 로우터의 치형

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1388376A (en) 1972-07-14 1975-03-26 Linde Ag Meshing screw pumps

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105257537A (zh) * 2015-11-03 2016-01-20 晗森机械（上海）有限公司 一种三齿螺杆压缩机的转子端面齿型
CN105257537B (zh) * 2015-11-03 2017-08-04 晗森机械（上海）有限公司 一种三齿螺杆压缩机的转子端面齿型

Also Published As

Publication number Publication date
ITBO20090442A1 (it) 2011-01-10
IT1395017B1 (it) 2012-09-05
WO2011004342A3 (fr) 2011-05-12

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