CN206448946U - A kind of conical screw rotor of self-balancing - Google Patents

Abstract

The utility model discloses a kind of conical screw rotor of self-balancing, screw rotor is integrally conical, from suction end (I I) to exhaust end (VII VII), rotor outside circle arc radius R₁It is gradually reduced, fillet radius R₃Gradually increase；The addendum thickness δ of screw rotor₁With thickness at root of tooth δ₂Axially maintain constant；In any axial positions, section molded line is change, but the type of the constituent curve of section molded line is identical, and all including 12 curves, connection is completely smooth between adjacent curve；A kind of varying pitch conical screw rotor of the self-balancing proposed can be effectively increased suction end working chamber volume, reduce exhaust end working chamber volume, rotor is had larger internal volume ratio, and ensure that the interstage seal performance of exhaust end and the intensity of rotor；In any axial positions of screw rotor, the centre of form of section molded line is all on the centre of gyration line of screw rotor, and the dynamic balance performance of screw rotor is good.

Description

A self-balancing conical screw rotor

technical field

The invention relates to a twin-screw vacuum pump, in particular to a self-balancing conical screw rotor suitable for the twin-screw vacuum pump.

Background technique

The twin-screw vacuum pump is a positive displacement vacuum pump, which is widely used in petrochemical, food and pharmaceutical, vacuum heat treatment, nano-manufacturing, and national defense technology fields because of its dry, oil-free suction chamber and stable and reliable operation; the twin-screw vacuum pump passes two The synchronous and opposite double-rotational motion of the two screw rotors completes the suction, transportation, compression and exhaust process of the gas in the pump chamber; the performance of the screw rotor and its cross-sectional profile directly affects the interstage sealing performance and mechanics of the screw vacuum pump. performance and ultimate vacuum.

The single-head conical screw rotor disclosed in patent CN101351646 has a large outer diameter at the suction end and a small outer diameter at the exhaust end, and there is an internal compression process during operation; Large, it takes up a part of the suction volume, which affects the suction volume. The gas pressure near the exhaust end is high, but the tooth top thickness is small, which cannot effectively prevent the high-pressure gas from interstage leakage through the tooth top surface; at the same time, the screw rotor, its shaft The centroid of the cross-section is not on the rotation centerline of the screw rotor, which is easy to generate eccentric force and affect the normal meshing.

Contents of the invention

In order to solve the eccentric force of the screw rotor in the above literature, the cusp of the section line, the large thickness of the tooth top at the suction end occupies the suction volume, and the small thickness of the tooth top at the exhaust end makes the gas pass through the interstage leakage of the tooth top surface. The larger problem, in order to enrich the types of screw rotors, the present invention proposes a self-balancing conical screw rotor; the screw rotor is conical, from the suction end (I-I) to the exhaust end (VII-VII), The cross-sectional profile of the screw rotor changes; the lead P of the screw rotor remains unchanged in the axial direction. By controlling the central angle α of the screw rotor addendum arc, the screw rotor addendum thickness δ ₁ and dedendum thickness δ ₂ is always constant and equal, so that the suction volume of the screw rotor at the suction end (I-I) can be increased, and the screw rotor can be effectively blocked between two adjacent working chambers at the exhaust end (VII-VII). The gas leaks through the interstage of the tooth top surface, and at the same time increases the strength of the screw rotor at the exhaust end (VII-VII) and reduces deformation; the cross-sectional profile of the screw rotor is smooth and can achieve correct meshing , to eliminate the adverse effects of rough joints and improve the stress of the screw rotor; at any axial position of the proposed screw rotor, its cross-sectional profile is S-shaped, and the centroid of the cross-sectional profile is in the screw rotor The center line of rotation makes the screw rotor have good dynamic balance performance; the proposed screw rotor can increase the volume of the working chamber at the suction end, reduce the volume of the working chamber at the exhaust end, and increase the internal volume ratio during the working process. The pumping speed and ultimate vacuum of the twin-screw vacuum pump are improved.

In order to achieve the above object, the present invention adopts the following technical solutions:

A self-balancing conical screw rotor proposed by the present invention, from the suction end (I-I) to the exhaust end (VII-VII), the screw rotor is conical, and the screw rotor is completely smooth, there is no smooth place; the lead P of the screw rotor remains constant along the axial direction; the thickness of the addendum δ ₁ and the thickness of the dedendum δ ₂ of the screw rotor are always constant and equal, that is, δ ₁ = δ ₂ ; at any axial position, The section line of the screw rotor is S-shaped, and the centroid of the section line is on the rotation center line of the screw rotor.

A self-balancing conical screw rotor. At any axial position, the cross-sectional profile of the screw rotor is different and changes, but the type and number of curves composed of each segment on the cross-sectional profile are the same, and there are 12 curves in total. , including: the first addendum arc AB, the first addendum arc BC, the equidistant curve CD of the first cycloid, the first dedendum arc DE, the envelope EF of the first connecting arc, the first The connecting arc FG, the second addendum arc GH, the second tooth tip arc HI, the equidistant curve IJ of the second cycloid, the second dedendum arc JK, the envelope KL of the second connecting arc, The second connection arc LA; two adjacent curves are completely connected smoothly, and there is no non-smooth connection point on the section line; the first addendum arc AB and the first tooth tip circle on the section line The arc BC, the equidistant curve CD of the first cycloid, the second dedendum arc JK, the envelope KL of the second connecting arc, and the second connecting arc LA are respectively related to the second addendum arc GH, the second The second tooth tip arc HI, the equidistant curve IJ of the second cycloid, the first dedendum arc DE, the envelope line EF of the first connecting arc, and the first connecting arc FG are symmetrical about the center of rotation O .

A self-balancing conical screw rotor, in the working process, the left-handed screw rotor (301) and the right-handed screw rotor (302) can achieve completely correct meshing in the synchronous counter-rotational double-rotation motion; at any axial position , the left-handed cross-sectional profile (201) of the left-handed screw rotor (301) is exactly the same as the right-handed cross-sectional profile (202) of the right-handed screw rotor (302), but the phases are different; the left-handed cross-sectional profile of the left-handed screw rotor (301) The first addendum arc AB, the first addendum arc BC, the equidistant curve CD of the first cycloid, the second root arc JK, and the envelope KL of the second connecting arc on the line (201) , the second connection arc LA, respectively with the second dedendum arc jk on the right-handed section profile line (202) of the right-handed screw rotor (302), the equidistant curve ij of the second cycloid, the second tooth tip The circular arc hi, the second addendum circular arc gh, the second connecting circular arc fg, and the envelope ef of the second connecting circular arc enable correct meshing.

A self-balancing conical screw rotor, the left-handed screw rotor (301) expands along the left-handed helix from the left-handed section line (201) from the suction end (Ⅰ-I) to the exhaust end (VII-VII), and the right-handed screw rotor The screw rotor (302) develops along a right-handed helix from the right-handed section line (202) from the suction end (I-I) to the exhaust end (VII-VII); The intersection point of the plane is the coordinate origin, and the center line of rotation is the z-axis to establish a three-dimensional space coordinate system. The equation of the helix is:

Left-handed helix:

Right-handed helix:

In the formula: τ—helix expansion angle, rad; R—helix base circle radius, mm; n—screw lead number; P—screw rotor lead;

While the cross-sectional profile of the screw rotor expands along the helical line, at any axial position, the addendum arc radius R ₁ , the dedendum arc radius R ₃ , and the central angle α of the addendum arc are also It changes with the change of the helix expansion angle τ, and its law is:

Addendum arc radius:

Root arc radius:

Central angle of addendum arc:

In the formula: R _s1 , R _d1 —respectively the radius of the addendum arc at the suction end (I-I) and exhaust end (VII-VII); R _s3 , R _{d3 —respectively} Ⅰ-I) and the radius of the dedendum arc at the exhaust end (VII-VII); α _s —the central angle of the addendum arc at the suction end (I-I).

5. A self-balancing conical screw rotor according to claim 1, characterized in that: the equations of the curves on the left-handed section profile (201) of the left-handed screw rotor (301) are as follows:

① The equation of the first addendum arc AB is:

②The equation of the first tooth tip circular arc BC is:

In the formula: r—the radius of the tooth tip arc; (x _M ,y _M )—the coordinates of the center point M of the tooth tip arc;

To determine the coordinates of the center point M(x _M , y _M ) of the tooth tip arc, firstly combine the following two equations to find the intersection point:

Rotate the intersection point determined by the above equation clockwise around the rotation center point O by an angle of β, and the center point M(x _M ,y _M ) of the tooth tip can be obtained; where

③ The method of determining the equidistant curve CD of the first cycloid is:

First determine a curve according to the following equation:

Rotate the curve determined by the above equation clockwise by an angle β around the center of rotation O to obtain the equidistant curve CD of the first cycloid;

④ The equation of the second dedendum arc JK is:

⑤ The method of determining the envelope KL of the second connecting arc is:

First determine a curve according to the following equation:

Rotate the initial curve determined by the above equation clockwise around the center of rotation O by an angle α to obtain the envelope KL of the second connecting arc, where α is the central angle of the addendum arc;

⑥The equation of the second connecting arc LA is:

In the formula: L _p - the length from the center point N of the second connecting arc LA to the center point O of the rotation, determined by the following formula:

The beneficial effects of the present invention are:

① A self-balancing conical screw rotor is proposed. The screw rotor is conical. From the suction end (I-I) to the exhaust end (VII-VII) of the screw rotor, the tooth top arc on the cross-sectional line The radius R ₁ gradually decreases, and the root arc radius R ₃ gradually increases, which can fully increase the volume of the working chamber at the suction end and reduce the volume of the working chamber at the exhaust end, so that the rotor has a larger internal volume ratio and improves the twin-screw The pumping speed of the vacuum pump;

② The screw rotor’s addendum thickness δ ₁ and dedendum thickness δ ₂ remain unchanged and equal in the axial direction, that is, δ ₁ = δ ₂ , which can further increase the volume of the working chamber at the suction end and effectively block the gas near the exhaust end Through the inter-stage leakage on the top surface of the tooth, and ensure the strength of the high-pressure side of the screw rotor, the deformation during operation is reduced;

③The cross-sectional profile of the screw rotor adopts a piece of tooth tip circular arc connecting the equidistant curve of the cycloid and the tooth tip circular arc. The screw rotor is completely smooth and can achieve correct meshing, and at the same time eliminate the stress concentration area of the non-smooth connection point , improve the stress condition of the screw rotor, and prevent the aggravation of leakage caused by sharp point wear;

④At any axial position, the cross-sectional profile of the screw rotor is S-shaped, and the centroid of the cross-sectional profile is on the rotation centerline of the screw rotor, that is, the screw rotor has good dynamic balance performance.

Description of drawings

Figure 1 is a cross-sectional profile diagram of a self-balancing conical screw rotor.

Fig. 2 is an meshing diagram of cross-sectional profiles of two screw rotors.

Figure 3 is a self-balancing conical screw rotor diagram.

Figure 4 is a meshing diagram of two self-balancing conical screw rotors during operation.

Fig. 5 is a cross-sectional profile meshing diagram of two screw rotors at any axial position.

In the figure: R ₁ , R ₂ , R ₃ —respectively represent the addendum arc radius, pitch circle radius, and dedendum arc radius on the profiled line, and the relationship between the lengths of the three is: 2R ₂ =R ₁ +R ₃ ; α—the center angle of the addendum arc; β—the phase angle of the center point M of the addendum arc relative to the x-axis; δ ₁ —the addendum thickness of the screw rotor; δ ₂ —the root thickness of the screw rotor; P —lead of screw rotor; 301—left-handed screw rotor; 302—right-handed screw rotor; 201—left-handed cross-sectional profile of left-handed screw rotor; 202—right-handed cross-sectional profile of right-handed screw rotor; points O, o—respectively is the center of rotation of the two screw rotor section profiles, and the axes where they are located are respectively the center lines of rotation of the two screw rotors.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, it is a cross-sectional line diagram of a self-balancing conical screw rotor; the cross-sectional line of a screw rotor refers to: use a plane perpendicular to the rotation centerline of the screw rotor to cut off the screw rotor from any axial position , the contour curve obtained at the cross-section; the cross-sectional profile of the screw rotor is surrounded by 12 curves, clockwise as follows: the first addendum arc AB, the first addendum arc BC, and the equidistant curve of the first cycloid CD, the first dedendum arc DE, the envelope EF of the first connecting arc, the first connecting arc FG, the second addendum arc GH, the second tooth tip arc HI, the second cycloid, etc. The distance curve IJ, the second dedendum arc JK, the envelope line KL of the second connecting arc, and the second connecting arc LA; the adjacent curves are smoothly connected, and there is no roughness on the section profile of the entire screw rotor Connection point; the entire cross-sectional profile is S-shaped and center-symmetrical, the first addendum arc AB, the first tooth tip arc BC, the equidistant curve CD of the first cycloid, and the second dedendum circle on the profile line The arc JK, the envelope KL of the second connecting arc, and the second connecting arc LA are respectively related to the second addendum arc GH, the second addendum arc HI, the equidistant curve IJ of the second cycloid, and the second addendum arc GH, the second addendum arc HI, the second cycloid A dedendum arc DE, the envelope EF of the first connecting arc, and the first connecting arc FG are centrosymmetric about the center point O of rotation.

As shown in Figure 2, it is the meshing diagram of the cross-sectional profiles of the two screw rotors; at the same axial position, the cross-sectional profiles of the two screw rotors are exactly the same, but the phases are different; The first addendum arc AB, the first addendum arc BC, the equidistant curve CD of the first cycloid, the first dedendum arc DE, the envelope EF of the first connecting arc, the first connecting arc FG, respectively with the second dedendum arc jk in the right-handed section profile line (202), the equidistant curve ij of the second cycloid, the second tooth tip arc hi, the second addendum arc gh, the second The connecting arc fg, the envelope ef of the second connecting arc enables correct meshing.

As shown in Figure 3, it is a self-balancing conical screw rotor diagram; I-I and VII-VII in the figure represent the axial positions corresponding to the suction end and exhaust end of the screw rotor respectively; the left-handed screw rotor (301) is The cross-section profile (201) develops along a left-handed helix from the suction end (I-I) to the exhaust end (VII-VII), and the right-handed screw rotor (302) starts from the suction end through the right-hand cross-section profile (202). (Ⅰ-Ⅰ) Expand toward the exhaust end (VII-VII) along a right-handed helix; at the same time as the helix unfolds, the addendum arc radius R ₁ on the section profile line gradually decreases, and the dedendum arc radius R ₃ Gradually increase, so that the overall shape of the screw rotor is conical; the regulation of the left-handed and right-handed helix is: use the left thumb to point from the suction end to the exhaust end, and the moving point on the helix rises along the direction of the other four fingers. It is left-handed; use the right thumb to point from the suction end to the exhaust end, and the moving point on the helix rises along the direction of the other four fingers, which is right-handed.

As shown in Figure 4, it is the meshing diagram of two self-balancing conical screw rotors during operation; the lead P of the screw rotor remains unchanged along the axial direction, and the thickness of the addendum δ ₁ and the thickness of the dedendum δ ₂ remain axially Invariant and equal, that is, δ ₁ = δ ₂ ; in the process of developing the rotor along the helical line of the cross-section, the value of the helical expansion angle τ is 0, For π, 2π, 3π, and 4π, the corresponding axial positions are represented by I-I, II-II, III-III, IV-IV, V-V, VI-VI, and VII-VII respectively.

As shown in Figure 5, it is the cross-sectional profile meshing diagram of two screw rotors at any axial position; Figure 5 (a), (b), (c), (d), (e), (f), (g) Instantaneous meshing diagrams of two screw rotor cross-sectional profiles corresponding to axial positions I-I, II-II, III-III, IV-IV, V-V, VI-VI, and VII-VII respectively; It can be seen that the cross-sectional profiles of the two screws are completely meshed at any axial position, so it can be explained that the two screw rotors are meshed with each other as a whole; at different axial positions, the main variation law of the cross-sectional profile is: from From the suction end (Ⅰ-Ⅰ) to the exhaust end (VII-VII), the addendum arc radius R ₁ of the rotor axial section profile line gradually decreases, and the dedendum arc radius R ₃ gradually increases; thus the The two screw rotors that are fully meshed with each other, from the suction end (I-I) to the exhaust end (VII-VII), the volume of the working chamber gradually decreases, so that the screw rotor has an internal compression process.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (8)

1. A self-balancing conical screw rotor, characterized in that: the screw rotor is conical, from the suction end (I-I) to the exhaust end (VII-VII), and the radius R of the addendum arc of the screw rotor ₁ gradually decreases, and the root arc radius R ₃ gradually increases, and the screw rotor is completely smooth without any roughness; the lead P of the screw rotor remains unchanged along the axial direction; the tooth top thickness δ ₁ and tooth The root thickness δ ₂ remains constant and equal in the axial direction, that is, δ ₁ = δ ₂ ; at any axial position, the section profile of the screw rotor is S-shaped, and the centroid of the section profile is at the rotation of the screw rotor center line. 2. A self-balancing conical screw rotor as claimed in claim 1, characterized in that: at any axial position, the cross-sectional profile of the screw rotor is different and changes, but the cross-sectional profile of each The type and quantity of segmented curves are the same, and there are 12 segments of curves in total, including: the first addendum arc AB, the first addendum arc BC, the equidistant curve CD of the first cycloid, the first dedendum arc DE, The envelope EF of the first connecting arc, the first connecting arc FG, the second addendum arc GH, the second tooth tip arc HI, the equidistant curve IJ of the second cycloid, and the second dedendum arc JK, the envelope KL of the second connecting arc, and the second connecting arc LA; the two adjacent curves are completely connected smoothly, and there is no non-smooth connection point on the section line; The first addendum arc AB, the first addendum arc BC, the equidistant curve CD of the first cycloid, the second root arc JK, the envelope KL of the second connecting arc, the second connecting arc LA, respectively with the second addendum arc GH, the second addendum arc HI, the equidistant curve IJ of the second cycloid, the first dedendum arc DE, the envelope EF of the first connecting arc, the second A connecting arc FG is centrosymmetric about the center point O of rotation. 3. A self-balancing conical screw rotor according to claim 1, characterized in that: during the working process, the left-handed screw rotor (301) and the right-handed screw rotor (302) are in synchronous different-direction double-rotational motion , can achieve completely correct meshing; at any axial position, the left-handed cross-sectional profile (201) of the left-handed screw rotor (301) is exactly the same as the right-handed cross-sectional profile (202) of the right-handed screw rotor (302); The first addendum arc AB, the first addendum arc BC, the equidistant curve CD of the first cycloid, the second dedendum arc JK, the first The envelope KL of the two connecting arcs and the second connecting arc LA are respectively connected with the second dedendum arc jk and the second cycloid on the right-handed section profile line (202) of the right-handed screw rotor (302). The equidistant curve ij, the second tooth tip circular arc hi, the second tooth tip circular arc gh, the second connecting circular arc fg, and the envelope ef of the second connecting circular arc enable correct meshing. 4. A self-balancing conical screw rotor according to claim 1, characterized in that: the left-handed screw rotor (301) is formed from the left-handed cross-sectional profile (201) from the suction end (I-I) to the exhaust end (VII-VII) develops along the left-handed helix, and the right-handed screw rotor (302) follows the right-handed helix from the suction end (I-I) to the exhaust end (VII-VII) from the right-handed cross-sectional profile (202) Expand; take the intersection point of the rotation center line of the screw rotor and the plane where the suction end is located as the coordinate origin, and use the rotation center line as the z-axis to establish a three-dimensional space coordinate system, and the helix equation is: Left-handed helix: Right-handed helix: In the formula: τ—helix expansion angle, rad; R—helix base circle radius, mm; n—screw lead number; P—screw rotor lead; While the cross-sectional profile of the screw rotor expands along the helix, at any axial position, the addendum arc R ₁ , the root arc radius R ₃ , and the central angle of the addendum arc of the screw rotor’s profile line α also changes with the change of the helix expansion angle τ, and its law is: Addendum arc radius: Root arc radius: Central angle of addendum arc: In the formula: R _s1 , R _d1 —respectively the radius of the addendum arc at the suction end (I-I) and exhaust end (VII-VII); R _s3 , R _{d3 —respectively} Ⅰ-I) and the radius of the dedendum arc at the exhaust end (VII-VII); α _s —the central angle of the addendum arc at the suction end (I-I). 5. A self-balancing conical screw rotor as claimed in claim 1, characterized in that: the equations of the curves on the left-handed section profile (201) of the left-handed screw rotor (301) are as follows: ① The equation of the first addendum arc AB is: ②The equation of the first tooth tip circular arc BC is: In the formula: r—the radius of the tooth tip arc; (x _M ,y _M )—the coordinates of the center point M of the tooth tip arc; To determine the coordinates of the center point M(x _M , y _M ) of the tooth tip arc, firstly combine the following two equations to find the intersection point: Rotate the intersection point determined by the above equation clockwise around the rotation center point O by an angle of β to obtain the tooth tip center point M(x _M ,y _M ); where ③ The method of determining the equidistant curve CD of the first cycloid is: First determine a curve according to the following equation: Rotate the curve determined by the above equation clockwise by an angle of β around the center of rotation O to obtain the equidistant curve CD of the first cycloid; ④ The equation of the second dedendum arc JK is: ⑤ The method of determining the envelope KL of the second connecting arc is: First determine a curve according to the following equation: Rotate the initial curve determined by the above equation clockwise by an angle α around the center of rotation O to obtain the envelope KL of the second connecting arc, where α is the central angle of the addendum arc; ⑥The equation of the second connecting arc LA is: In the formula: L _p - the length from the center point N of the second connecting arc LA to the center point O of the rotation, determined by the following formula: 6. A twin-screw vacuum pump, characterized in that: the self-balancing tapered full-smooth twin-screw rotor as claimed in claim 1 is used. 7. A twin-screw compressor, characterized in that: the self-balancing variable-pitch conical screw rotor as claimed in claim 1 is used. 8. A twin-screw expander, characterized in that: the self-balancing variable-pitch conical screw rotor as claimed in claim 1 is used.