CN105485014A - Equal-screw-pitch and variable-tooth-width screw rotor - Google Patents

Equal-screw-pitch and variable-tooth-width screw rotor Download PDF

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Publication number
CN105485014A
CN105485014A CN201610004897.4A CN201610004897A CN105485014A CN 105485014 A CN105485014 A CN 105485014A CN 201610004897 A CN201610004897 A CN 201610004897A CN 105485014 A CN105485014 A CN 105485014A
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China
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screw rotor
tau
tooth
cycloid
axial
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CN201610004897.4A
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CN105485014B (en
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王君
刘宏杰
张凌宏
刘强
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China University of Petroleum Beijing CUPB
China University of Petroleum UPC East China
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China University of Petroleum UPC East China
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C29/00Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08Rotary-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
    • F04C18/082Details specially related to intermeshing engagement type pumps
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08Rotary-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
    • F04C18/12Rotary-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 of other than internal-axis type
    • F04C18/14Rotary-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 of other than internal-axis type with toothed rotary pistons
    • F04C18/16Rotary-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 of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C25/00Adaptations of pumps for special use of pumps for elastic fluids
    • F04C25/02Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00Components
    • F04C2240/20Rotors

Abstract

The invention discloses an equal-screw-pitch and variable-tooth-width screw rotor and belongs to the field of dry type double-screw vacuum pumps. The screw pitches (P1, P2, P3 and P4) of the screw rotor are kept unchanged from a low-pressure end face I-I of the screw rotor to a high-pressure end face VI-VI of the screw rotor, but the tooth widths, including the tooth top face widths (M1, M2 and M3) and the tooth root face widths (N1, N2 and N3), of the screw rotor are gradually increased. At any axial position, the molded line of the axial section of the screw rotor includes five sections of curves which are a round involute AB, a tooth top arc BC, a cycloid CD, a tooth root arc DE and a cycloid EA, wherein the tooth root arc DE and the round involute AB are in smooth connection with the cycloid EA. According to the screw rotor, the volume of a low-pressure work cavity is increased, the volume of a high-pressure work cavity is reduced, the inner volume specific ratio is increased, the length of a screw is reduced, high strength and good sealing performance are achieved, and the final vacuum and the pumping speed of the double-screw vacuum pumps are increased.

Description

A kind of screw rotor of uniform pitch Varied pole piece
Technical field
The present invention relates to dry type Twin-screw vacuum pump, be particularly applicable to the screw rotor of a kind of uniform pitch Varied pole piece of dry type Twin-screw vacuum pump.
Background technique
Dry type Twin-screw vacuum pump is a kind of vacuum displacement pump, moved to dual AC power by 2 synchronous differents that can realize the screw rotor engaged, multiple periodically variable working chamber volume is formed between 2 screw rotors and pump housing inner chamber, realize the suction of gas, supercharging and discharge, form vacuum in the inlet of pump; Active chamber is by being formed between 2 intermeshing screw rotors and pump housing inner chamber, sealing between each active chamber be by 2 screw rotors between engagement realize, therefore screw rotor is the most key component, the sealability of screw rotor, efficiency, area utilization factor, directly affect the boundary dimension of Twin-screw vacuum pump, pumping speed and ultimate vacuum.
Screw rotor makes axial screw by the axial cross section molded line of screw rotor along circular helix to launch to generate; Conventional screw rotor is the screw rotor of the facewidth such as uniform pitch, is characterized in that the pitch of screw rotor is constant, the facewidth of screw rotor from the low pressure end face of screw rotor to high pressure end face, comprises Topland width and tooth bottom width is also constant; The working chamber volume formed by the screw rotor of the facewidth such as uniform pitch is constant, and interior volume specific ratio equals 1, and namely high-pressure working chamber volume equals operating on low voltage chamber volume; The facewidth size of screw rotor affects the leakage by Topland and tooth bottom surface of gas in high and low pressure active chamber, affects the intensity of screw rotor, rigidity and axial dimension simultaneously.
In the active chamber that screw rotor is formed, because in the active chamber at low pressure end face I-I place, gas pressure is lower, and in the active chamber at high pressure end face VI-VI place, gas pressure is higher; According to this feature, the Changing Pattern of the working chamber volume that the screw rotor of optimization is formed and the facewidth should be: high-pressure working chamber volume is less, and operating on low voltage chamber volume is larger; The screw rod facewidth at high-pressure working chamber place is comparatively large, and the screw rod facewidth at operating on low voltage chamber place is less.
Summary of the invention
The present invention proposes a kind of screw rotor of uniform pitch Varied pole piece, from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, the pitch (P of screw rotor 1, P 2, P 3, P 4) remain unchanged, and the facewidth of screw rotor, comprise Topland width (M 1, M 2, M 3) and bottom width (N 1, N 2, N 3) but increase gradually; The active chamber that formed of screw rotor thus, its high-pressure working chamber volume is less, and operating on low voltage chamber volume is comparatively large, comparatively large in the facewidth of high-pressure working chamber place screw rotor, less in the facewidth of operating on low voltage chamber place screw rotor.
The present invention proposes a kind of Twin-screw vacuum pump, it is characterized in that: the screw rotor using uniform pitch Varied pole piece proposed by the invention.
The present invention proposes a kind of double-screw compressor, it is characterized in that: the screw rotor using uniform pitch Varied pole piece proposed by the invention.
The present invention proposes a kind of twin-screw expander, it is characterized in that: the screw rotor using uniform pitch Varied pole piece proposed by the invention.
To achieve these goals, the present invention adopts following technological scheme:
Determine the axial cross section molded line of screw rotor in axially different position, namely determine the set of curves of axial cross section molded line; The axial cross section molded line of screw rotor refers to by a plane with screw rotor axis perpendicular, goes to cut a screw rotor, the profilogram intercepted in different axial positions.
The screw rotor of uniform pitch Varied pole piece proposed by the invention, in axially different position, the axial cross section molded line of screw rotor is not identical, but the type of its constituent curve is identical; In arbitrary axial positions, the axial cross section molded line of screw rotor all comprises 5 sections of curves and 2 points, be followed successively by: circle involute AB, some B, tooth top circular arc BC, some C, cycloid CD, tooth root circular arc DE, cycloid EA, wherein tooth root circular arc DE, circle involute AB are smoothly connected with cycloid EA, and the central angle ∠ DOE of the central angle ∠ BOC of tooth top circular arc BC and tooth root circular arc DE is equal, is central angle θ; In different axial positions, the axial cross section molded line of screw rotor is not identical, change with the difference of place axial position, from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, the axial cross section molded line of screw rotor with the Changing Pattern of axial position is: the Base radius R of circle involute AB bincrease gradually, the generation angle α of circle involute AB reduces gradually, and the central angle θ of tooth top circular arc BC and tooth root circular arc DE increases gradually.
Twin-screw vacuum pump comprises intermeshing two screw rotors, i.e. left-hand screw rotor (301) and right-hand screw rotor (302); Regulation that is left-handed, dextrorotation is: left-handed is that rotation direction meets lefft-hand rule, the direction indication of left hand thumb is from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, namely circular helix move axially direction, all the other four directions referred to are sense of rotation of circular helix; Dextrorotation is that rotation direction meets right-hand rule, and the direction indication of right hand thumb is from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, namely circular helix move axially direction, all the other four directions referred to are sense of rotation of circular helix.
Intermeshing 2 screw rotors: left-hand screw rotor (301) and right-hand screw rotor (302), all comprise 5 flank of tooth and 2 circular helixes, the composition flank of tooth and the circular helix of right-hand screw rotor (302) are followed successively by: the cycloid flank of tooth (1), pitch face (2), circular helix (3), Topland (4), circular helix (5), the recessed flank of tooth (6), tooth flank (7), and pitch face (2), tooth flank (7) are all smoothly connected with the cycloid flank of tooth (1); The composition flank of tooth and the circular helix of left-hand screw rotor (301) are followed successively by: the cycloid flank of tooth (1 '), pitch face (2 '), circular helix (3 '), Topland (4 '), circular helix (5 '), the recessed flank of tooth (6 '), tooth flank (7 '), and pitch face (2 '), tooth flank (7 ') are all smoothly connected with the cycloid flank of tooth (1 '); In the working procedure that synchronous different moves to dual AC power, the cycloid flank of tooth (1) of right-hand screw rotor (302), pitch face (2), circular helix (3), Topland (4), circular helix (5), the recessed flank of tooth (6), tooth flank (7), can realize correct engaging with the circular helix (3 ') of left-hand screw rotor (301), pitch face (2 '), the cycloid flank of tooth (1 '), tooth flank (7 '), the recessed flank of tooth (6 '), circular helix (5 '), Topland (4 ') respectively; In arbitrary axial positions, left-hand screw rotor (301) is identical with the axial cross section molded line of right-hand screw rotor (302), and circle involute AB in the axial cross section molded line (201) of left-hand screw rotor (301), some B, tooth top circular arc BC, some C, cycloid CD, tooth root circular arc DE and cycloid EA, correct engaging can be realized with circle involute ba, the cycloid ae in the axial cross section molded line (202) of right-hand screw rotor (302), tooth root circular arc ed, cycloid dc, some c, tooth top circular arc cb, some b respectively.
Left-hand screw rotor (301) does spiral expansion by the axial cross section molded line (201) of a series of screw rotor along left-handed uniform pitch circular helix and generates; Right-hand screw rotor (302) does spiral expansion by the axial cross section molded line (202) of a series of screw rotor along dextrorotation uniform pitch circular helix and generates; Left-handed uniform pitch circular helix is different from the rotation direction of dextrorotation uniform pitch circular helix;
The equation of left-handed uniform pitch circular helix is:
x ( τ ) = R c o s ( τ ) y ( τ ) = - R s i n ( τ ) , τ ∈ [ 0 , 2 n π ] z ( τ ) = P 2 π τ
The equation of dextrorotation uniform pitch circular helix is:
x ( τ ) = R c o s ( τ ) y ( τ ) = R s i n ( τ ) , τ ∈ [ 0 , 2 n π ] z ( τ ) = P 2 π τ
In formula: τ is the spiral angle of spread, rad; R is helix Base radius, mm; N is the spiral number of turns, n >=2; P is the pitch of screw rotor, mm.
In arbitrary axial positions, the axial cross section molded line of screw rotor all comprises 5 sections of curves: circle involute AB, tooth top circular arc BC, cycloid CD, tooth root circular arc DE, cycloid EA; At different axial positions, i.e. corresponding different spiral angle of spread τ, the set of curves equation of each curve is as follows:
1. the set of curves equation of circle involute AB is:
x ( t , τ ) = R b ( τ ) ( cos ( t - α ( τ ) ) + t sin ( t - α ( τ ) ) ) y ( t , τ ) = R b ( τ ) ( sin ( t - α ( τ ) ) - t cos ( t - α ( τ ) ) )
In formula: t is angle parameter, rad; R b(τ) be the Base radius of axially different position circle involute AB; α (τ) is the generation angle of axially different position circle involute AB; R b(τ) determined by following formula with α (τ):
R b ( τ ) = R b e - R b s e 2 n π k - 1 ( e k τ - 1 ) + R b s
α ( τ ) = t a n ( a r c c o s ( R b ( τ ) R 2 ) ) - a r c c o s ( R b ( τ ) R 2 )
In formula: k is coefficient; R bs, R bebe respectively the Base radius of the circle involute AB in the axial cross section molded line of the screw rotor of low pressure end face I-I and high pressure end face VI-VI, mm;
2. the set of curves equation of tooth top circular arc BC is:
x ( t ) = R 1 cos t y ( t ) = R 1 sin t
In formula: R 1for tooth top radius of arc, mm;
3. the set of curves equation of cycloid CD is:
x ( t ) = 2 R 2 cos t + R 1 c o s 2 t y ( t ) = 2 R 2 sin t + R 1 s i n 2 t
In formula: R 2for Pitch radius, mm;
4. the set of curves equation of tooth root circular arc DE is:
x ( t ) = R 3 cos t y ( t ) = R 3 sin t
In formula: R 3for fillet radius, mm;
5. the set of curves equation of cycloid EA is:
x ( t , τ ) = 2 R 2 cos ( t + θ ( τ ) ) + R 1 cos ( 2 t + θ ( τ ) ) y ( t , τ ) = 2 R 2 sin ( t + θ ( τ ) ) + R 1 sin ( 2 t + θ ( τ ) )
In formula: θ (τ) is the central angle of axially different position tooth top circular arc BC and tooth root circular arc DE, is determined by following formula:
θ ( τ ) = π + α ( τ ) - [ t a n ( a r c c o s ( R b ( τ ) R 1 ) ) - a r c c o s ( R b ( τ ) R 1 ) ]
Beneficial effect of the present invention is:
The screw rotor of a kind of uniform pitch Varied pole piece proposed, from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, the pitch (P of screw rotor 1, P 2, P 3, P 4) remain unchanged, and the facewidth of screw rotor, comprise Topland width (M 1, M 2, M 3) and bottom width (N 1, N 2, N 3) but increase gradually; The low pressure end face I-I of screw rotor can be used as the suction end of Twin-screw vacuum pump, and high pressure end face VI-VI can be used as the exhaust end of Twin-screw vacuum pump; Thereby increase aspirated volume, reduce delivery space, add interior volume specific ratio, achieve the Changing Pattern of working chamber volume from suction end to exhaust end consistent with the Changing Pattern of gas boosting process in active chamber, namely air aspiration cavity volume is large, and discharge chamber volume is little; Simultaneously larger in the exhaust end screw rod facewidth, less in the suction end screw rod facewidth, reduce the Leakage Gas by Topland between each active chamber, the Changing Pattern of the facewidth from suction end to exhaust end achieving screw rotor is consistent with the Changing Pattern of gas pressure in active chamber; Therefore this screw rotor has compact structure, intensity is high, rigidity is high, the advantage of good seal performance, improves ultimate vacuum and the pumping speed of Twin-screw vacuum pump.
Compared with the screw rotor of the facewidth such as existing uniform pitch, the screw rotor tool of a kind of uniform pitch Varied pole piece proposed has the following advantages: 1. can form larger operating on low voltage chamber volume, less high-pressure working chamber volume, therefore there is larger content ratio, be conducive to the ultimate vacuum and the pumping speed that improve vacuum pump; 2. at the active chamber place that pressure is higher, the facewidth of screw rotor is comparatively large, has stronger inter-stage and leaks blocking capability, can make the leakage of reduction gas between each active chamber; 3. intensity is high, rigidity is high.
Accompanying drawing explanation
Fig. 1 is the axial cross section molded lines of uniform pitch Varied pole piece screw rotor.
Fig. 2 is the engagement figure between intermeshing 2 screw rotor axial cross section molded line.
Fig. 3 is the screw rotor figure of uniform pitch Varied pole piece.
Fig. 4 is the engagement figure of the screw rotor of 2 uniform pitch Varied pole piece.
In figure: R 1-Outside radius; R 2-Pitch radius; R 3-root radius; R bthe Base radius of-circle involute; The generation angle of α-circle involute; The central angle of θ-tooth top circular arc BC and tooth root circular arc DE; 201,202-screw rotor axial cross section molded line; 301-left-hand screw rotor; 302-right-hand screw rotor; 1,1 '-cycloid flank of tooth; 2,2 '-pitch face; 3,3 ', 5,5 '-circular helix; 4,4 '-Topland; 6,6 '-recessed flank of tooth; 7,7 '-tooth flank; P 1, P 2, P 3, P 4the pitch of-screw rotor; M 1, M 2, M 3the Topland width of-screw rotor; N 1, N 2, N 3the bottom width of-screw rotor.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the invention will be further described.
As shown in Figure 1, for the axial cross section molded lines of uniform pitch Varied pole piece screw rotor, in arbitrary axial positions, the axial cross section molded line of screw rotor all comprises 5 sections of curves and 2 points, is followed successively by: circle involute AB, some B, tooth top circular arc BC, some C, cycloid CD, tooth root circular arc DE, cycloid EA; Wherein tooth root circular arc DE, circle involute AB are smoothly connected with cycloid EA, and the central angle ∠ DOE of the central angle ∠ BOC of tooth top circular arc BC and tooth root circular arc DE is equal, is central angle θ.
As shown in Figure 2, for the engagement figure between intermeshing 2 screw rotor axial cross section molded line, in same axial positions, left-hand screw rotor (301) is identical with the axial cross section molded line of right-hand screw rotor (302), and the circle involute AB in the axial cross section molded line (201) of left-hand screw rotor (301), point B, tooth top circular arc BC, point C, cycloid CD, tooth root circular arc DE and cycloid EA, respectively with the circle involute ba in the axial cross section molded line (202) of right-hand screw rotor (302), cycloid ae, tooth root circular arc ed, cycloid dc, point c, tooth top circular arc cb, point b can realize correct engagement.
As shown in Figure 3, be the screw rotor figure of uniform pitch Varied pole piece, Twin-screw vacuum pump comprises 2 screw rotors: left-hand screw rotor (301) and right-hand screw rotor (302); Left-hand screw rotor (301) does spiral expansion by the axial cross section molded line (201) of a series of screw rotor along left-handed uniform pitch circular helix and generates; Right-hand screw rotor (302) does spiral expansion by the axial cross section molded line (202) of a series of screw rotor along dextrorotation uniform pitch circular helix and generates; Left-handed uniform pitch circular helix is different from the rotation direction of dextrorotation uniform pitch circular helix.
As shown in Figure 4, be the engagement figure of the screw rotor of 2 uniform pitch Varied pole piece, intermeshing 2 screw rotors: left-hand screw rotor (301) and right-hand screw rotor (302), all comprise 5 flank of tooth, with 2 circular helixes, the composition flank of tooth and the circular helix of right-hand screw rotor (302) are followed successively by: the cycloid flank of tooth (1), pitch face (2), circular helix (3), Topland (4), circular helix (5), the recessed flank of tooth (6), tooth flank (7), and pitch face (2), tooth flank (7) is all smoothly connected with the cycloid flank of tooth (1), the composition flank of tooth and the circular helix of left-hand screw rotor (301) are followed successively by: the cycloid flank of tooth (1 '), pitch face (2 '), circular helix (3 '), Topland (4 '), circular helix (5 '), the recessed flank of tooth (6 '), tooth flank (7 '), and pitch face (2 '), tooth flank (7 ') are all smoothly connected with the cycloid flank of tooth (1 '), in the working procedure that synchronous different moves to dual AC power, the cycloid flank of tooth (1) of right-hand screw rotor (302), pitch face (2), circular helix (3), Topland (4), circular helix (5), the recessed flank of tooth (6), tooth flank (7), can realize correct engaging with the circular helix (3 ') of left-hand screw rotor (301), pitch face (2 '), the cycloid flank of tooth (1 '), tooth flank (7 '), the recessed flank of tooth (6 '), circular helix (5 '), Topland (4 ') respectively, in arbitrary axial positions, left-hand screw rotor (301) is all identical with the axial cross section molded line of right-hand screw rotor (302).
Intermeshing 2 screw rotors, the spiral number of turns of left-hand screw rotor (301) and right-hand screw rotor (302) is all greater than 2.
As shown in Figure 4, be the engagement figure of the screw rotor of 2 uniform pitch Varied pole piece, the pitch of screw rotor remains unchanged from low pressure end face I-I to high pressure end face VI-VI, i.e. P 1=P 2=P 3=P 4, but the width of Topland and tooth flank increases from low pressure end face I-I gradually to high pressure end face VI-VI, i.e. M 1< M 2< M 3, N 1< N 2< N 3; Sectional view I-I, II-II, III-III, IV-IV, V-V, VI-VI, for spiral angle of spread τ be respectively 0,2 π, 3 π, 4 π, 6 π, 8 π time, the engagement figure of the axial cross section molded line of screw rotor; In arbitrary axial positions, the axial cross section molded line of screw rotor all comprises 5 sections of curves: circle involute AB, tooth top circular arc BC, cycloid CD, tooth root circular arc DE, cycloid EA; From the low pressure end face I-I of screw rotor to high pressure end face VI-VI, the axial cross section molded line of screw rotor with the Changing Pattern of axial position is: the Base radius R of circle involute AB bincrease gradually, the generation angle α of circle involute AB reduces gradually, and the central angle θ of tooth top circular arc BC and tooth root circular arc DE increases gradually.The active chamber that formed of screw rotor thus, its high-pressure working chamber volume is less, and operating on low voltage chamber volume is comparatively large, comparatively large in the facewidth of high-pressure working chamber place screw rotor, less in the facewidth of operating on low voltage chamber place screw rotor.
By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technological scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (7)

1. a screw rotor for uniform pitch Varied pole piece, is characterized in that: from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, the pitch (P of screw rotor 1, P 2, P 3, P 4) remain unchanged, and the facewidth of screw rotor, comprise Topland width (M 1, M 2, M 3) and bottom width (N 1, N 2, N 3) but increase gradually; The active chamber that formed of screw rotor thus, its high-pressure working chamber volume is less, and operating on low voltage chamber volume is comparatively large, comparatively large in the facewidth of high-pressure working chamber place screw rotor, less in the facewidth of operating on low voltage chamber place screw rotor.
2. the screw rotor of a kind of uniform pitch Varied pole piece as claimed in claim 1, it is characterized in that: in arbitrary axial positions, the axial cross section molded line of screw rotor all comprises 5 sections of curves and 2 points, be followed successively by: circle involute AB, some B, tooth top circular arc BC, some C, cycloid CD, tooth root circular arc DE, cycloid EA, wherein tooth root circular arc DE, circle involute AB are smoothly connected with cycloid EA, and the central angle ∠ DOE of the central angle ∠ BOC of tooth top circular arc BC and tooth root circular arc DE is equal, is central angle θ; In different axial positions, the axial cross section molded line of screw rotor is not identical, and change with the difference of place axial position, from the low pressure end face I-I of screw rotor to high pressure end face VI-VI, the axial cross section molded line of screw rotor with the Changing Pattern of axial position is: the Base radius R of circle involute AB bincrease gradually, the generation angle α of circle involute AB reduces gradually, and the central angle θ of tooth top circular arc BC and tooth root circular arc DE increases gradually.
3. the screw rotor of a kind of uniform pitch Varied pole piece as claimed in claim 1, it is characterized in that: screw rotor comprises 5 flank of tooth and 2 circular helixes, be followed successively by: the cycloid flank of tooth (1), pitch face (2), circular helix (3), Topland (4), circular helix (5), the recessed flank of tooth (6), tooth flank (7), and pitch face (2), tooth flank (7) are all smoothly connected with the cycloid flank of tooth (1); In the working procedure that synchronous different moves to dual AC power, the cycloid flank of tooth (1) of right-hand screw rotor (302), pitch face (2), circular helix (3), Topland (4), circular helix (5), the recessed flank of tooth (6), tooth flank (7), can realize correct engaging with the circular helix (3 ') of left-hand screw rotor (301), pitch face (2 '), the cycloid flank of tooth (1 '), tooth flank (7 '), the recessed flank of tooth (6 '), circular helix (5 '), Topland (4 ') respectively; In arbitrary axial positions, left-hand screw rotor (301) is identical with the axial cross section molded line of right-hand screw rotor (302), circle involute AB in the axial cross section molded line (201) of left-hand screw rotor (301), some B, tooth top circular arc BC, some C, cycloid CD, tooth root circular arc DE and cycloid EA, can realize correct engaging with circle involute ba, the cycloid ae in the axial cross section molded line (202) of right-hand screw rotor (302), tooth root circular arc ed, cycloid dc, some c, tooth top circular arc cb, some b respectively.
4. the screw rotor of a kind of uniform pitch Varied pole piece as described in claim 1, left-hand screw rotor (301) does spiral expansion by the axial cross section molded line (201) of a series of screw rotor along left-handed uniform pitch circular helix and generates; Right-hand screw rotor (302) does spiral expansion by the axial cross section molded line (202) of a series of screw rotor along dextrorotation uniform pitch circular helix and generates; Left-handed uniform pitch circular helix is different from the rotation direction of dextrorotation uniform pitch circular helix; The equation of left-handed uniform pitch circular helix is:
x ( &tau; ) = R c o s ( &tau; ) y ( &tau; ) = - R s i n ( &tau; ) , &tau; &Element; &lsqb; 0 , 2 n &pi; &rsqb; z ( &tau; ) = P 2 &pi; &tau;
The equation of dextrorotation uniform pitch circular helix is:
x ( &tau; ) = R c o s ( &tau; ) y ( &tau; ) = R s i n ( &tau; ) , &tau; &Element; &lsqb; 0 , 2 n &pi; &rsqb; z ( &tau; ) = P 2 &pi; &tau;
In formula: τ is the spiral angle of spread, rad; R is helix Base radius, mm; N is the spiral number of turns, n >=2; P is the pitch of screw rotor, mm;
In arbitrary axial positions, the axial cross section molded line of screw rotor all comprises 5 sections of curves: circle involute AB, tooth top circular arc BC, cycloid CD, tooth root circular arc DE, cycloid EA; At different axial positions, i.e. corresponding different spiral angle of spread τ, the set of curves equation of each curve is as follows:
1. the set of curves equation of circle involute AB is:
x ( t , &tau; ) = R b ( &tau; ) ( c o s ( t - &alpha; ( &tau; ) ) + t s i n ( t - &alpha; ( &tau; ) ) ) y ( t , &tau; ) = R b ( &tau; ) ( s i n ( t - &alpha; ( &tau; ) ) - t c o s ( t - &alpha; ( &tau; ) ) )
In formula: t is angle parameter, rad; R b(τ) be the Base radius of axially different position circle involute AB; α (τ) is the generation angle of axially different position circle involute AB; R b(τ) determined by following formula with α (τ):
R b ( &tau; ) = R b e - R b s e 2 n &pi; k - 1 ( e k &tau; - 1 ) + R b s
&alpha; ( &tau; ) = t a n ( arccos ( R b ( &tau; ) R 2 ) ) - arccos ( R b ( &tau; ) R 2 )
In formula: k is coefficient; R bs, R bebe respectively the Base radius of the circle involute AB in the screw rotor axial cross section molded line of low pressure end face I-I and high pressure end face VI-VI, mm;
2. the set of curves equation of tooth top circular arc BC is:
x ( t ) = R 1 cos t y ( t ) = R 1 sin t
In formula: R 1for tooth top radius of arc, mm;
3. the set of curves equation of cycloid CD is:
x ( t ) = 2 R 2 cos t + R 1 c o s 2 t y ( t ) = 2 R 2 sin t + R 1 s i n 2 t
In formula: R 2for Pitch radius, mm;
4. the set of curves equation of tooth root circular arc DE is:
x ( t ) = R 3 cos t y ( t ) = R 3 sin t
In formula: R 3for fillet radius, mm;
5. the set of curves equation of cycloid EA is:
x ( t , &tau; ) = 2 R 2 c o s ( t + &theta; ( &tau; ) ) + R 1 cos ( 2 t + &theta; ( &tau; ) ) y ( t , &tau; ) = 2 R 2 sin ( t + &theta; ( &tau; ) ) + R 1 sin ( 2 t + &theta; ( &tau; ) )
In formula: θ (τ) is the central angle of axially different position tooth top circular arc BC and tooth root circular arc DE, is determined by following formula:
&theta; ( &tau; ) = &pi; + &alpha; ( &tau; ) - &lsqb; t a n ( arccos ( R b ( &tau; ) R 1 ) ) - arccos ( R b ( &tau; ) R 1 ) &rsqb;
5. a Twin-screw vacuum pump, is characterized in that: the screw rotor using uniform pitch Varied pole piece as claimed in claim 1.
6. a double-screw compressor, is characterized in that: the screw rotor using uniform pitch Varied pole piece as claimed in claim 1.
7. a twin-screw expander, is characterized in that: the screw rotor using uniform pitch Varied pole piece as claimed in claim 1.
CN201610004897.4A 2016-01-05 2016-01-05 A kind of screw rotor of uniform pitch Varied pole piece Expired - Fee Related CN105485014B (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105952641A (en) * 2016-07-11 2016-09-21 中国石油大学(华东) Three-section type screw rotor and twin-screw vacuum pump comprising same
CN106438370A (en) * 2016-12-07 2017-02-22 中国石油大学(华东) Self-balancing variable-pitch cone-shaped screw rotor
CN107816383A (en) * 2017-08-07 2018-03-20 张益民 To cycloid rotor engine of changing one's position

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US3501807A (en) * 1966-09-10 1970-03-24 Rolf Kestermann Mas Fab Masticating system for plastic materials
CN1444700A (en) * 2000-07-25 2003-09-24 阿特里尔斯布希股份有限公司 Twin screw rotors and displacement machines containing the same
US20040247465A1 (en) * 2001-09-27 2004-12-09 Masashi Yoshimura Screw type vacuum pump
US20080193301A1 (en) * 2007-02-13 2008-08-14 Kabushiki Kaisha Toyota Jidoshokki Composite fluid machine
CN201366785Y (en) * 2009-03-20 2009-12-23 韩旻 Three-change screw rod with screw pitch, groove depth and groove width
CN205277822U (en) * 2016-01-05 2016-06-01 中国石油大学(华东) Uniform pitch becomes screw rotor of breadth of tooth

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3501807A (en) * 1966-09-10 1970-03-24 Rolf Kestermann Mas Fab Masticating system for plastic materials
CN1444700A (en) * 2000-07-25 2003-09-24 阿特里尔斯布希股份有限公司 Twin screw rotors and displacement machines containing the same
US20040247465A1 (en) * 2001-09-27 2004-12-09 Masashi Yoshimura Screw type vacuum pump
US20080193301A1 (en) * 2007-02-13 2008-08-14 Kabushiki Kaisha Toyota Jidoshokki Composite fluid machine
CN201366785Y (en) * 2009-03-20 2009-12-23 韩旻 Three-change screw rod with screw pitch, groove depth and groove width
CN205277822U (en) * 2016-01-05 2016-06-01 中国石油大学(华东) Uniform pitch becomes screw rotor of breadth of tooth

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105952641A (en) * 2016-07-11 2016-09-21 中国石油大学(华东) Three-section type screw rotor and twin-screw vacuum pump comprising same
CN106438370A (en) * 2016-12-07 2017-02-22 中国石油大学(华东) Self-balancing variable-pitch cone-shaped screw rotor
CN106438370B (en) * 2016-12-07 2018-07-06 中国石油大学(华东) A kind of varying pitch conical screw rotor of self-balancing
CN107816383A (en) * 2017-08-07 2018-03-20 张益民 To cycloid rotor engine of changing one's position

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