A cross-axis conical twin-screw expander

Abstract

The invention discloses a cross-axis conical twin-screw expander, comprising a conical male screw rotor (1), a conical female screw rotor (2), a conical pump body (3), a left transmission gear (4) and a right transmission gear (5); the conical male screw rotor (1) and the conical female screw rotor (2) are both linearly conical from a low-pressure end face (Ⅱ-Ⅱ) to a high-pressure end face (Ⅰ-Ⅰ), so that the two screw rotors can achieve correct meshing under the cross-axis transmission in different directions and ensure effective sealing between the two screw rotors; the contact line between the two screw rotors is shorter at the high-pressure end, which effectively reduces the gas leakage during the working process; the internal volume ratio of the twin-screw expander is improved, so that the axial size of the twin-screw expander is more compact, which is of great significance to improving the working performance of the twin-screw expander and improving the cycle power generation efficiency.

Description

Technical Field

[0001] The invention relates to a twin-screw expander, in particular to a cross-axis conical twin-screw expander. Background Art

[0002] Twin-screw expander is a volumetric expander, mainly composed of a pair of screw rotors, housing, bearings, synchronous gears, sealing components and couplings. Its working process includes suction process, expansion process and exhaust process. The fluid is expanded and works by reducing pressure in the closed volume formed by the two screws and the pump chamber, pushing the screw to rotate to achieve energy conversion. Twin-screw expander has the advantages of strong adaptability to working fluids, simple operation, small footprint and wide application range. It is suitable for technical applications of industrial waste heat power generation and geothermal power generation.

[0003] In the application of twin-screw expanders, their content volume ratio has a great influence on the power generation cycle system. The existing mutually meshing twin-screw rotors can form a relatively small content volume; a twin-screw expander with a larger content volume ratio is conducive to improving the performance of the system, such as a twin-screw expander with a large content volume can achieve a full-flow power generation cycle. In order to improve the content volume ratio of the screw expander, a Chinese patent (patent number CN 109458226 A) proposes a variable-section screw rotor for a twin-screw expander. The rotor uses a method of gradually changing the cross-sectional profile to make the suction volume of the screw rotor smaller and the exhaust volume larger, thereby improving the content volume ratio formed by the twin-screw rotor, but this method has limited improvement in the content volume ratio. A Chinese patent (patent number CN104141606A) proposes a conical twin-screw compression pump that uses female and male conical screws with a 5:3 transmission. Theoretically, it has a higher compression coefficient, but the contact line of the two plane sections in the case of cross-axis meshing can only be a straight line, and the plane profile lines will be incompletely meshed or not meshed in the case of cross-axis meshing, and the sealing performance between the two screw rotors cannot be guaranteed. Summary of the invention

[0004] In order to improve the content volume ratio of the twin-screw expander and meet the requirements of the power generation cycle system for the content volume ratio and expansion ratio, the present invention proposes a cross-axis conical twin-screw expander; the two screw rotors are both linearly conical, and the two screw rotors can achieve a cross-axis meshing with a transmission ratio of 3:2 during operation. Under the condition of the same external dimensions, the content volume ratio is 2 to 3 times that of the existing parallel-axis twin-screw expander; under the condition of the same content volume ratio, the structure is simpler and more compact than the original twin-screw expander. The present invention adopts a spherical cross section to complete the design of the two screw rotors, so that the two screw rotors can achieve correct meshing under the cross-axis working state and ensure effective sealing between the two screw rotors. The content volume ratio of the twin-screw expander is improved, the gas axial force on the screw rotor is reduced, and the axial structure of the twin-screw expander is more compact, which is of great significance to improving the working performance of the twin-screw expander and improving the power generation cycle efficiency of the system.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A cross-axis conical twin-screw expander comprises: a conical male screw rotor, a conical female screw rotor, a conical pump body, a left transmission gear and a right transmission gear, wherein the conical male screw rotor and the conical female screw rotor are both linearly conical from a low-pressure end face to a high-pressure end face, that is, the pitch radius of the conical male screw rotor and the conical female screw rotor decreases linearly;

[0007] The end surface of the conical male screw rotor and the conical female screw rotor at the high pressure end surface is a concave spherical surface with a radius of R h ; The pitch radius of the conical male screw rotor at the high pressure end face is r mh , and satisfies r mh =R h ·sinθ1, θ1 is the cone half angle of the male screw rotor pitch cone; the pitch radius of the conical female screw rotor at the high pressure end face is r fh , and satisfies r fh =R h ·sinθ2; θ2 is the cone half angle of the pitch cone of the female screw rotor;

[0008] The end surface of the conical male screw rotor and the conical female screw rotor at the low-pressure end surface is an outward convex spherical surface with a radius of R l ; The pitch radius of the conical male screw rotor at the low-pressure end face is r ml , and satisfies r ml =R l ·sinθ1; the pitch radius of the conical female screw rotor at the low-pressure end face is r fl , and satisfies r fl =R l ·sinθ2;

[0009] In the working meshing state, the rotation axis OA of the conical male screw rotor and the rotation axis OB of the conical female screw rotor intersect at one point, the intersection point is O, the angle between the two rotation axes is ∠AOB=θ, the value range is 0°<θ<90°, and satisfies θ=θ1+θ2.

[0010] A cross-axis conical twin-screw expander, with the intersection O of the rotation axis OA of the conical male screw rotor and the rotation axis OB of the conical female screw rotor as the center of the sphere, and the radius is R (R h <R<R l ) is a spherical surface, the intersection section of the spherical surface and the conical male screw rotor is a left spherical section, and the contour line of the left spherical section is composed of a spherical cycloid GH, a spherical arc HI, a spherical cycloid IJ, a spherical cycloid JK and a spherical section arc KL;

[0011] The intersection O of the rotation axis OP of the tapered male screw rotor and the rotation axis OQ of the tapered female screw rotor is taken as the center of the sphere, and the radius is R (R o <R<R i ) is a spherical surface, the intersection section of the spherical surface and the conical female screw rotor is a right spherical section, and the contour line of the right spherical section is composed of a spherical straight line AB, a spherical arc BC, a spherical cycloid CD, a spherical straight line DE and a spherical arc EF;

[0012] The spherical cycloid GH, spherical arc HI, spherical cycloid IJ, spherical cycloid JK and spherical section arc KL in the contour line of the left spherical section of the conical male screw rotor respectively mesh correctly with the spherical straight line AB, spherical arc BC, spherical cycloid CD, spherical straight line DE and spherical arc EF in the contour line of the right spherical section of the conical female screw rotor to achieve a transmission ratio of 2:3.

[0013] A cross-axis conical twin-screw expander, wherein the conical pump body is composed of a conical male rotor pump chamber and a conical female rotor pump chamber; the conical male rotor pump chamber and the conical female rotor pump chamber are linearly conical; that is, from the low-pressure end face to the high-pressure end face, the wall radius of the conical male rotor pump chamber and the conical female rotor pump chamber decreases linearly;

[0014] The pump cavity in the conical pump body accommodates a cross-axis screw; the conical male screw rotor is installed in the conical male rotor pump cavity, and the central axis OM of the conical male rotor pump cavity coincides with the rotation axis OA of the conical male screw rotor; the conical female screw rotor is installed in the conical female rotor pump cavity, and the central axis ON of the conical female rotor pump cavity coincides with the rotation axis OB of the conical female screw rotor;

[0015] The conical male rotor pump cavity and the conical female rotor pump cavity are located on the same spherical surface Q1 at the low-pressure end surface. The radius of the spherical surface Q1 is R1. The radial radius of the conical male rotor pump cavity at the low-pressure end surface is r L , and satisfy the relationship: Where, κ is the wall radius coefficient;

[0016] The conical male rotor pump cavity and the conical female rotor pump cavity are located on the same spherical surface Q2 at the high-pressure end surface. The radius of the spherical surface Q2 is R2. The radial radius of the conical male rotor pump cavity at the high-pressure end surface is r H , and satisfy the relationship:

[0017] The conical pump body is provided with an exhaust port at the low-pressure end surface; the conical pump body is provided with an air intake port at the high-pressure end surface.

[0018] A cross-axis conical twin-screw expander, during operation, the conical male screw rotor and the conical female screw rotor are respectively connected to a pair of non-orthogonal gears: a left transmission gear and a right transmission gear; in the working state, the rotation axis of the left transmission gear coincides with the rotation axis OP of the conical male screw rotor, and the rotation axis of the right transmission gear coincides with the rotation axis OQ of the conical female screw rotor.

[0019] A cross-axis conical twin-screw compressor uses the conical male screw rotor, the conical female screw rotor and the conical pump body.

[0020] The beneficial effects of the present invention are:

[0021] ① A cross-axis conical twin-screw expander is proposed, wherein the conical male screw rotor (1) and the conical female screw rotor (2) are both conical, and the two screw rotors can achieve cross-correct meshing, and have a larger internal volume ratio and expansion ratio under the same structural parameters. Compared with a traditional twin-screw expander, the internal volume ratio is increased by 2 to 3 times;

[0022] ② Since the end surfaces of the two screw rotors at the high-pressure end surfaces are reduced, the axial force of the gas on the two screw rotors is reduced;

[0023] ③ During operation, the spatial contact line length of the two screw rotors is reduced, thereby reducing inter-stage gas leakage;

[0024] ④The screw rotor has a short axial dimension and a compact structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural diagram of the cross-axis conical twin-screw expander.

[0026] Figure 2 Figure 1 is a diagram of a conical male screw rotor (1).

[0027] Figure 3 FIG. 2 is a diagram of a conical female screw rotor (2).

[0028] Figure 4 This is a diagram of the meshing of two screw rotors.

[0029] Figure 5 It is a composition curve diagram of the contour line of the left spherical section (101).

[0030] Figure 6 It is a composition curve diagram of the contour line of the right spherical cross section (201).

[0031] Figure 7 Figure 3 shows the conical pump body (3) of a cross-axis conical twin-screw expander.

[0032] In the figure: 1—conical male screw rotor; 2—conical female screw rotor; 3—conical pump body; 4—left transmission gear; 5—right transmission gear; 101—left spherical section; 201—right spherical section; R h —The radius of the concave spherical surface of the conical male screw rotor (1) and the conical female screw rotor (2) at the high-pressure end surface (Ⅰ-Ⅰ); r mh —the pitch radius of the conical male screw rotor (1) at the high-pressure end face (Ⅰ-Ⅰ); θ1—the cone half angle of the male screw rotor pitch cone; r fh —the pitch radius of the conical female screw rotor (2) at the high pressure end face (Ⅰ-Ⅰ); θ2—the cone half angle of the female screw rotor pitch cone; R l —radius of the outer convex spherical surface of the conical male screw rotor (1) and the conical female screw rotor (2) at the low-pressure end surface (Ⅱ-Ⅱ); r ml —The pitch radius of the conical male screw rotor (1) at the low-pressure end face (Ⅱ-Ⅱ); r fl —the pitch radius of the conical female screw rotor (2) at the low-pressure end face (II-II); θ—the angle between the two rotation axes of the conical male screw rotor (1) and the conical female screw rotor (2); DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] like Figure 1 As shown, it is a structural diagram of a cross-axis conical twin-screw expander, including: a conical male screw rotor 1, a conical female screw rotor 2, a conical pump body 3, a left transmission gear 4 and a right transmission gear 5. The conical male screw rotor 1 and the conical female screw rotor 2 are both linearly tapered from the low-pressure end surface II-II to the high-pressure end surface I-I, that is, the pitch circle radius of the conical male screw rotor 1 and the conical female screw rotor 2 decreases linearly;

[0035] like Figure 2 As shown, it is a three-dimensional diagram of the conical male screw rotor 1. The end surface of the conical male screw rotor 1 and the conical female screw rotor 2 at the high-pressure end surface Ⅰ-Ⅰ is an inward concave spherical surface with a radius of R h ; The pitch radius of the conical male screw rotor 1 at the high pressure end surface Ⅰ-Ⅰ is r mh , and satisfies r mh =R h ·sinθ1, θ1 is the cone half angle of the pitch cone of the male screw rotor;

[0036] like Figure 3 As shown, it is a three-dimensional diagram of the conical female screw rotor 2. The pitch radius of the conical female screw rotor 2 at the high-pressure end surface Ⅰ-Ⅰ is r fh , and satisfies r fh =R h ·sinθ2; θ2 is the cone half angle of the pitch cone of the female screw rotor;

[0037] The end surface of the conical male screw rotor 1 and the conical female screw rotor 2 at the low-pressure end surface Ⅱ-Ⅱ is an outward convex spherical surface with a radius of R l ; The pitch radius of the conical male screw rotor 1 at the low-pressure end surface Ⅱ-Ⅱ is r ml , and satisfies r ml =R l ·sinθ1; the pitch radius of the conical female screw rotor 2 at the low-pressure end surface Ⅱ-Ⅱ is r fl , and satisfies r fl =R l ·sinθ2;

[0038] like Figure 4 As shown, it is a meshing diagram of two screw rotors. In the working meshing state, the rotation axis OA of the conical male screw rotor 1 and the rotation axis OB of the conical female screw rotor 2 intersect at one point, and the intersection point is O. The angle between the two rotation axes is ∠AOB=θ, and its value range is 0°<θ<90°, and satisfies θ=θ1+θ2.

[0039] like Figure 5 As shown, it is a composition curve diagram of the contour line of the left spherical section 101, with the intersection O of the rotation axis OA of the conical male screw rotor 1 and the rotation axis OB of the conical female screw rotor 2 as the sphere center, and the radius is R (R h <R<R l ) is a spherical surface, the intersection of the spherical surface and the conical male screw rotor 1 is a left spherical section 101, and the contour line of the left spherical section 101 is composed of a spherical cycloid GH, a spherical arc HI, a spherical cycloid IJ, a spherical cycloid JK and a spherical section arc KL;

[0040] like Figure 6 As shown, it is a composition curve diagram of the contour line of the right spherical section 201, with the intersection O of the rotation axis OP of the conical male screw rotor 1 and the rotation axis OQ of the conical female screw rotor 2 as the center of the sphere, and the radius is R (R o <R<R i ) is a spherical surface, the intersection of the spherical surface and the conical female screw rotor 2 is a right spherical section 201, and the contour line of the right spherical section 201 is composed of a spherical straight line AB, a spherical arc BC, a spherical cycloid CD, a spherical straight line DE and a spherical arc EF;

[0041] The spherical cycloid GH, spherical arc HI, spherical cycloid IJ, spherical cycloid JK and spherical section arc KL in the contour line of the left spherical section 101 of the conical male screw rotor 1 are respectively correctly meshed with the spherical straight line AB, spherical arc BC, spherical cycloid CD, spherical straight line DE and spherical arc EF in the contour line of the right spherical section 201 of the conical female screw rotor 2 to achieve a transmission ratio of 2:3.

[0042] like Figure 7 As shown, it is a pump body 3 diagram of a cross-axis conical twin-screw expander, the conical pump body 3 is composed of a conical male rotor pump chamber 301 and a conical female rotor pump chamber 302; the conical male rotor pump chamber 301 and the conical female rotor pump chamber 302 are linearly conical; that is, from the low-pressure end face II-II to the high-pressure end face I-I, the wall radius of the conical male rotor pump chamber 301 and the conical female rotor pump chamber 302 decreases linearly;

[0043] The pump chamber in the conical pump body 3 accommodates a cross-axis screw; the conical male screw rotor 1 is installed in the conical male rotor pump chamber 301, and the central axis OM of the conical male rotor pump chamber 301 coincides with the rotation axis OA of the conical male screw rotor 1; the conical female screw rotor 2 is installed in the conical female rotor pump chamber 302, and the central axis ON of the conical female rotor pump chamber 302 coincides with the rotation axis OB of the conical female screw rotor 2;

[0044] The conical male rotor pump chamber 301 and the conical female rotor pump chamber 302 are located on the same spherical surface Q1 at the low-pressure end surface II-II. The radius of the spherical surface Q1 is R1. The radial radius of the pump chamber of the conical male rotor pump chamber 301 at the low-pressure end surface II-II is r L , and satisfy the relationship: Where, κ is the wall radius coefficient;

[0045] The conical male rotor pump chamber 301 and the conical female rotor pump chamber 302 are located on the same spherical surface Q2 at the high pressure end surface Ⅰ-Ⅰ. The radius of the spherical surface Q2 is R2. The radial radius of the pump chamber of the conical male rotor pump chamber 301 at the high pressure end surface Ⅰ-Ⅰ is r H , and satisfy the relationship:

[0046] The conical pump body 3 is provided with an exhaust port 303 at the low-pressure end surface II-II; the conical pump body 3 is provided with an air intake port 304 at the high-pressure end surface I-I.

[0047] During operation, the conical male screw rotor 1 and the conical female screw rotor 2 are respectively connected to a pair of non-orthogonal gears: a left transmission gear 4 and a right transmission gear 5; in the working state, the rotation axis of the left transmission gear 4 coincides with the rotation axis OP of the conical male screw rotor 1, and the rotation axis of the right transmission gear 5 coincides with the rotation axis OQ of the conical female screw rotor 2.

[0048] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A cross-axis conical twin-screw expander, comprising: A conical male screw rotor (1), a conical female screw rotor (2), a conical pump body (3), a left transmission gear (4) and a right transmission gear (5), characterized in that: the conical male screw rotor (1) and the conical female screw rotor (2) are both linearly conical from the low-pressure end surface (II-II) to the high-pressure end surface (I-I), and the pitch circle radius of the conical male screw rotor (1) and the conical female screw rotor (2) are both linearly reduced; The conical male screw rotor (1) and the conical female screw rotor (2) are both concave spherical surfaces with the same radius at the high pressure end surface (Ⅰ-Ⅰ), and the radius of the concave spherical surface is R h ; The pitch radius of the conical male screw rotor (1) at the high pressure end face (Ⅰ-Ⅰ) is r mh , and satisfies r mh =R h sinθ1, θ1 is the cone half angle of the pitch cone of the conical male screw rotor (1); the pitch radius of the conical female screw rotor (2) at the high pressure end face (Ⅰ-Ⅰ) is r fh , and satisfies r fh =R h ·sinθ2; θ2 is the cone half angle of the pitch cone of the conical female screw rotor (2); The conical male screw rotor (1) and the conical female screw rotor (2) are both convex spherical surfaces with the same radius at the low-pressure end surface (Ⅱ-Ⅱ), and the radius of the convex spherical surface is R l ; The pitch radius of the conical male screw rotor (1) at the low-pressure end face (Ⅱ-Ⅱ) is r ml , and satisfies r ml =R l ·sinθ1; the pitch radius of the conical female screw rotor (2) at the low-pressure end face (Ⅱ-Ⅱ) is r fl , and satisfies r fl =R l ·sinθ2; In the working meshing state, the rotation axis OA of the conical male screw rotor (1) and the rotation axis OB of the conical female screw rotor (2) intersect at a point, the intersection point is O, and the angle between the two rotation axes is ∠AOB=θ, the value range is 0°<θ<90°, and θ=θ1+θ2 is satisfied; The intersection O of the rotation axis OA of the conical male screw rotor (1) and the rotation axis OB of the conical female screw rotor (2) is taken as the center of the sphere, and the radius is R (R h <R<R l ) is a spherical surface, the intersection section of the spherical surface and the conical male screw rotor (1) is a left spherical section (101), and the intersection section of the spherical surface and the conical female screw rotor (2) is a right spherical section (201); The contour line of the left spherical cross section (101) is composed of a left first spherical cycloid GH, a left first spherical arc HI, a left second spherical cycloid IJ, a left third spherical cycloid JK and a left second spherical arc KL; The contour line of the right spherical cross section (201) is composed of a right first spherical straight line AB, a right first spherical arc BC, a right spherical cycloid CD, a right second spherical straight line DE and a right second spherical arc EF; In the working meshing state, the conical male screw rotor (1) and the conical female screw rotor (2) are driven by a cross-axis with a transmission ratio of 2:3, and the two spherical sections can achieve correct meshing; the left first spherical cycloid GH, the left first spherical arc HI, the left second spherical cycloid IJ, the left third spherical cycloid JK and the left second spherical arc KL in the contour line of the left spherical section (101) of the conical male screw rotor (1) can respectively achieve correct meshing with the right first spherical straight line AB, the right first spherical arc BC, the right spherical cycloid CD, the right second spherical straight line DE and the right second spherical arc EF in the contour line of the right spherical section (201) of the conical female screw rotor (2).

2. A cross-axis conical twin-screw expander according to claim 1, characterized in that: The conical pump body (3) is composed of a conical male rotor pump chamber (301) and a conical female rotor pump chamber (302); a conical male screw rotor (1) is installed in the conical male rotor pump chamber (301), and the central axis OM of the conical male rotor pump chamber (301) coincides with the rotation axis OA of the conical male screw rotor (1); a conical female screw rotor (2) is installed in the conical female rotor pump chamber (302), and the central axis ON of the conical female rotor pump chamber (302) coincides with the rotation axis OB of the conical female screw rotor (2).

3. The cross-axis conical twin-screw expander according to claim 1, characterized in that: During operation, the conical male screw rotor (1) and the conical female screw rotor (2) are coaxially connected to a pair of non-orthogonal gears: a left transmission gear (4) and a right transmission gear (5); in the working state, the rotation axis of the left transmission gear (4) coincides with the rotation axis OP of the conical male screw rotor (1), and the rotation axis of the right transmission gear (5) coincides with the rotation axis OQ of the conical female screw rotor (2).

4. A cross-axis conical twin-screw compressor, characterized in that: The conical male screw rotor (1), the conical female screw rotor (2) and the conical pump body (3) described in claim 1 are used.

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