Rotors of steam screw compressors and expanders

Abstract

The present invention discloses a rotor of a steam screw compressor and an expander, including a rotor profile. The rotor profile includes a pair of meshing male rotor profile and female rotor profile, and both the male rotor profile and the female rotor profile adopt a bilateral asymmetric structure composed of an envelope line and an arc. The male rotor profile is sequentially connected by six quadratic curves including a first male rotor envelope line A1B1, a second male rotor envelope line B1C1, a first male rotor arc C1D1, a second male rotor arc D1E1, a third male rotor envelope line E1F1, and a third male rotor arc F1G1. The female rotor profile is sequentially connected by six quadratic curves including a first female rotor arc A2B2, a second female rotor arc B2C2, a third female rotor arc C2D2, a female rotor envelope line D2E2, a fourth female rotor arc E2F2, and a fifth female rotor arc F2G2. The rotor profile of the present invention forms a face seal when the male and female rotors are meshed, which not only greatly improves the sealing effect, but also makes the steam not generate a large velocity gradient difference when passing through the sealing surface of the tiny gap.

Description

Technical Field

[0001] The present invention relates to the technical field of steam compression, and particularly relates to a rotor of a steam screw compressor and an expander. Background Art

[0002] In screw products, the rotor profile is a decisive factor for product performance and has gone through three generations of development. The first-generation rotor profile is a symmetric circular arc profile, which has the characteristics of easy design, simple production and processing, and convenient measurement. This profile was widely used in the initial screw products. The second-generation rotor profile is an asymmetric profile, which adds points, straight lines, and cycloids to the curve composition of the profile. Compared with the symmetric circular arc profile, the asymmetric profile significantly reduces the area of the leakage triangle, which is only about one-tenth of the latter, and significantly improves the performance of the screw product. The third-generation rotor profile is developed by the main manufacturers of each screw product according to the characteristics of their respective products. However, its main feature is that the composition curves of the profile no longer include points and straight lines, but are all composed of quadratic curves such as circular arcs, ellipses, and parabolas. Representatives include the GHH profile, the Hitachi profile, and the SRM-D profile, etc.

[0003] However, since the advent of screw products, they have been mainly applied to the fields of refrigeration and air compression, and the working fluids used are mainly refrigerants and air. The above-mentioned third-generation profiles are also designed for these application scenarios.

[0004] Steam compression and expansion are emerging application fields of screw products in the past decade. The steam working fluid is also significantly different from traditional refrigerant and air working fluids in physical property parameters. At present, most steam screw products only slightly modify the structure of traditional screw products and directly put them into use, without targeting the new application scenario of steam compression and expansion. Therefore, it is necessary to design a brand-new efficient profile. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above background art and provide a rotor of a steam screw compressor and an expander. The rotor profile is an efficient profile suitable for steam working fluids, changes the situation where steam screw products use traditional screw product profiles, and improves the performance of steam screw products.

[0006] To achieve the above purpose, a rotor of a steam screw compressor and an expander designed by the present invention includes a rotor profile. The rotor profile includes a pair of meshing male rotor profiles and female rotor profiles. Both the male rotor profile and the female rotor profile adopt a bilateral asymmetric structure composed of an envelope line and a circular arc.

[0007] The profile of the male rotor is composed of six quadratic curves, namely, the first male rotor envelope curve A1B1, the second male rotor envelope curve B1C1, the first male rotor arc C1D1, the second male rotor arc D1E1, the third male rotor envelope curve E1F1, and the third male rotor arc F1G1, which are connected in sequence.

[0008] The profile of the female rotor is composed of six quadratic curves, namely, the first female rotor arc A2B2, the second female rotor arc B2C2, the third female rotor arc C2D2, the female rotor envelope curve D2E2, the fourth female rotor arc E2F2, and the fifth female rotor arc F2G2, which are connected in sequence.

[0009] Furthermore, taking O1 as the center of the male rotor and O2 as the center of the female rotor to establish a coordinate system, the distance between O1 and O2 is the center distance A between the male rotor and the female rotor. The number of teeth of the male rotor and the female rotor are Z1 and Z2 respectively, and the tooth heights of the male rotor and the female rotor are RC1 and RC2 respectively. The pitch circle radius of the male rotor R1W = A * Z1 / (Z1 + Z2), and the pitch circle radius of the female rotor R2W = A * Z2 / (Z1 + Z2).

[0010] Furthermore, the first male rotor envelope curve A1B1 is tangent to the second male rotor envelope curve B1C1 at point B1; the second male rotor envelope curve B1C1 is tangent to the first male rotor arc C1D1 at point C1; the center of the first male rotor arc C1D1 is on the line connecting the centers O1 and O2 of the male and female rotors, and point D1 is on the line connecting the centers O1 and O2 of the male and female rotors, and is tangent to the second male rotor arc D1E1 at point D1; the center of the second male rotor arc D1E1 is on the line connecting the centers O1 and O2 of the male and female rotors, and is tangent to the third male rotor envelope curve E1F1 at point E1; the third male rotor envelope curve E1F1 is tangent to the third male rotor arc F1G1 at point F1.

[0011] Furthermore, the center of the first female rotor arc A2B2 is on the line connecting the center O2 of the female rotor and point A2, and the first female rotor arc A2B2 of the female rotor is tangent to the second female rotor arc B2C2 of the female rotor at point B2; the second female rotor arc B2C2 is tangent to the third female rotor arc C2D2 at point C2; the center of the third female rotor arc C2D2 is on the line connecting the centers O1 and O2 of the male and female rotors, and point D2 is on the line connecting the centers O1 and O2 of the male and female rotors, and is tangent to the female rotor envelope curve D2E2 at point D2; the female rotor envelope curve D2E2 is tangent to the fourth female rotor arc E2F2 at point E2; the center of the fourth female rotor arc E2F2 is on the line connecting the center O2 of the female rotor and point F2, and the fourth female rotor arc E2F2 of the female rotor is tangent to the fifth female rotor arc F2G2 of the female rotor at point F2.

[0012] Further, the point G1 of the third male rotor arc F1G1 makes the angle ∠A1O1G1 satisfy the requirement that ∠A1O1G1 = 360° / Z1.

[0013] Further, the point G2 of the fifth female rotor arc F2G2 makes the angle ∠A2O2G2 satisfy the requirement that ∠A2O2G2 = 360° / Z2.

[0014] Further, the coordinate equations of the arcs in the male rotor profile and the female rotor profile are as follows:

[0015]

[0016] In the formula, x: the abscissa of the profile, unit: mm; y: the ordinate of the profile, unit: mm; r: the radius of the arc, unit: mm; t: the angle of the arc, unit: degree; a: the abscissa of the center of the circle corresponding to the arc, unit: mm; b: the ordinate of the center of the circle corresponding to the arc, unit: mm.

[0017] Further, the coordinate equations of the envelope lines in the male rotor profile and the female rotor profile are as follows:

[0018]

[0019] In the formula, x: the abscissa of the profile, unit: mm; y: the ordinate of the profile, unit: mm; r: the radius of the arc, unit: mm; t: the angle of the arc, unit: degree; A: the center distance, unit: mm; α: the rotation angle of the profile, unit: degree; c1: the coordinate transformation coefficient from the dynamic coordinates of the male rotor to the static coordinates; c2: the tooth number ratio of the male and female rotors; c3: the coordinate transformation coefficient from the dynamic coordinates of the female rotor to the static coordinates; c4: the transformation coefficient from the dynamic coordinates of the male rotor to the dynamic coordinates of the female rotor.

[0020] Still further, the arcs and envelope lines in the male rotor profile and the female rotor profile are conjugate curves to each other.

[0021] Even further, the tooth number ratio of the male rotor to the female rotor is 4 - 6:5 - 8.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] Firstly, all the component lines of the male and female rotor profiles of the present invention are quadratic curves, so that a surface seal is formed when the male and female rotors are meshed. This not only greatly improves the sealing effect, but also makes it impossible to generate a large velocity gradient difference when water vapor passes through the sealed surface of the tiny gap, significantly reducing the starting noise, and moreover, it is more conducive to the smooth meshing of the rotors.

[0024] Secondly, the rotor profiles designed by the present invention have no straight lines and no sharp points, which is convenient for the processing, transportation and storage of the rotors, and there is less wear during the operation of the rotors.

[0025] Thirdly, for the working conditions of the steam screw products, the rotor profile of the present invention sets the meshing clearance with sectional weighted values, improving the performance of the steam screw products.

[0026] Fourthly, in the profile design of the present invention, angles are used as control parameters, and geometric constraint conditions are utilized to reduce the number of control parameters, thus reducing the number of control parameters and the design difficulty.

[0027] Fifthly, on the composition curves of the male and female rotor profiles of the present invention, the original circular arc curves are concentratedly arranged on the female rotor, improving the success rate of profile generation.

[0028] Sixthly, the present invention concentrates the original curves on one rotor and uses angles as control parameters, greatly reducing the design difficulty of the profile.

[0029] Seventhly, the rotor profile of the present invention is specially designed for the emerging application field of steam screw products. It not only has the advantages of the traditional third-generation profile, but also can greatly improve the performance of steam screw products. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the rotors of a steam screw compressor and an expander. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following describes in detail the implementation of the present invention in combination with the implementation cases, but they do not constitute a limitation to the present invention and are only for illustration. Meanwhile, the advantages of the present invention will become clearer and easier to understand.

[0032] As Figure 1 shown, a rotor of a steam screw compressor and an expander includes a pair of meshing male rotor profile and female rotor profile. Both the male rotor profile and the female rotor profile adopt a bilateral asymmetric structure composed of an envelope line and a circular arc, and the composition lines are all quadratic curves. A coordinate system is established with O1 as the center of the male rotor and O2 as the center of the female rotor. The distance between O1 and O2 is the center distance A between the male rotor and the female rotor. The number of teeth of the male rotor and the female rotor are Z1 and Z2 respectively, and the tooth heights of the male rotor and the female rotor are RC1 and RC2 respectively. The pitch circle radius of the male rotor R1W = A * Z1 / (Z1 + Z2), and the pitch circle radius of the female rotor R2W = A * Z2 / (Z1 + Z2). The circular arcs and envelope lines in the male rotor profile and the female rotor profile are all conjugate curves to each other. The tooth number ratio of the male rotor to the female rotor is 4 - 6:5 - 8. In this embodiment, the number of teeth of the male and female rotors are Z1 = 4 and Z2 = 6 respectively, and the center distance A between the male and female rotors is 200 mm.

[0033] The profile curve of the male rotor is composed of six quadratic curves, namely the first male rotor envelope curve A1B1, the second male rotor envelope curve B1C1, the first male rotor arc C1D1, the second male rotor arc D1E1, the third male rotor envelope curve E1F1, and the third male rotor arc F1G1, which are connected in sequence. The first male rotor envelope curve A1B1 is tangent to the second male rotor envelope curve B1C1 at point B1. The second male rotor envelope curve B1C1 is tangent to the first male rotor arc C1D1 at point C1. The center of the first male rotor arc C1D1 lies on the line connecting the centers O1 and O2 of the male and female rotors. Point D1 lies on the line connecting the centers O1 and O2 of the male and female rotors and is tangent to the second male rotor arc D1E1 at point D1. The center of the second male rotor arc D1E1 lies on the line connecting the centers O1 and O2 of the male and female rotors and is tangent to the third male rotor envelope curve E1F1 at point E1. The third male rotor envelope curve E1F1 is tangent to the third male rotor arc F1G1 at point F1. Point G1 on the third male rotor arc F1G1 makes the angle ∠A1O1G1 satisfy the requirement ∠A1O1G1 = 360° / Z1.

[0034] The profile curve of the female rotor is composed of six quadratic curves, namely the first female rotor arc A2B2, the second female rotor arc B2C2, the third female rotor arc C2D2, the female rotor envelope curve D2E2, the fourth female rotor arc E2F2, and the fifth female rotor arc F2G2, which are connected in sequence. The center of the first female rotor arc A2B2 lies on the line connecting the center O2 of the female rotor and point A2. The first female rotor arc A2B2 of the female rotor is tangent to the second female rotor arc B2C2 of the female rotor at point B2. The second female rotor arc B2C2 is tangent to the third female rotor arc C2D2 at point C2. The center of the third female rotor arc C2D2 lies on the line connecting the centers O1 and O2 of the male and female rotors. Point D2 lies on the line connecting the centers O1 and O2 of the male and female rotors and is tangent to the female rotor envelope curve D2E2 at point D2. The female rotor envelope curve D2E2 is tangent to the fourth female rotor arc E2F2 at point E2. The center of the fourth female rotor arc E2F2 lies on the line connecting the center O2 of the female rotor and point F2. The fourth female rotor arc E2F2 of the female rotor is tangent to the fifth female rotor arc F2G2 of the female rotor at point F2. Point G2 on the fifth female rotor arc F2G2 makes the angle ∠A2O2G2 satisfy the requirement ∠A2O2G2 = 360° / Z2.

[0035] In the above technical solution, the coordinate equations of the first male rotor arc C1D1, the second male rotor arc D1E1, the third male rotor arc F1G1 in the male rotor profile curve, and the first female rotor arc A2B2, the second female rotor arc B2C2, the third female rotor arc C2D2, the fourth female rotor arc E2F2, and the fifth female rotor arc F2G2 in the female rotor profile curve are as follows:

[0036]

[0037] where x: abscissa of the profile curve, unit: mm; y: ordinate of the profile curve, unit: mm; r:

[0038] radius of the arc, unit: mm; t: angle of the arc, unit: degree; a: abscissa of the center of the circle corresponding to the arc, unit: mm; b: ordinate of the center of the circle corresponding to the arc, unit: mm.

[0039] In the above technical solution, the coordinate equations of the first male rotor envelope line A1B1, the second male rotor envelope line B1C1, the third male rotor envelope line E1F1 in the male rotor profile curve and the female rotor envelope line D2E2 in the female rotor profile curve are as follows:

[0040]

[0041] where x: abscissa of the profile curve, unit: mm; y: ordinate of the profile curve, unit: mm; r:

[0042] radius of the arc, unit: mm; t: angle of the arc, unit: degree; A: center distance, unit: mm; α: rotation angle of the profile curve, unit: degree; c1: coordinate transformation coefficient from the dynamic coordinate of the male rotor to the static coordinate; c2: tooth number ratio of the male and female rotors; c3: coordinate transformation coefficient from the dynamic coordinate of the female rotor to the static coordinate; c4: transformation coefficient from the dynamic coordinate of the male rotor to the dynamic coordinate of the female rotor.

[0043] The above is only the specific implementation manner of the present invention. It should be noted that any change or replacement that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The rest not described in detail is the prior art.

Claims

1. A rotor of a steam screw compressor and expander, including a rotor profile line, characterized in that: The rotor profile includes a pair of meshing male rotor profiles and female rotor profiles, and both the male rotor profile and the female rotor profile adopt a bilateral asymmetric structure composed of an envelope curve and an arc. The male rotor profile is composed of six quadratic curves, namely the first male rotor envelope curve (A1B1), the second male rotor envelope curve (B1C1), the first male rotor arc (C1D1), the second male rotor arc (D1E1), the third male rotor envelope curve (E1F1), and the third male rotor arc (F1G1), which are connected in sequence. The female rotor profile is composed of six quadratic curves, namely the first female rotor arc (A2B2), the second female rotor arc (B2C2), the third female rotor arc (C2D2), the female rotor envelope curve (D2E2), the fourth female rotor arc (E2F2), and the fifth female rotor arc (F2G2), which are connected in sequence. The first male rotor envelope curve (A1B1) is tangent to the second male rotor envelope curve (B1C1) at point B1; the second male rotor envelope curve (B1C1) is tangent to the first male rotor arc (C1D1) at point C1; the center of the first male rotor arc (C1D1) is on the connection line of the centers O1 and O2 of the male and female rotors, point D1 is on the connection line of the centers O1 and O2 of the male and female rotors, and is tangent to the second male rotor arc (D1E1) at point D1; the center of the second male rotor arc (D1E1) is on the connection line of the centers O1 and O2 of the male and female rotors, and is tangent to the third male rotor envelope curve (E1F1) at point E1; the third male rotor envelope curve (E1F1) is tangent to the third male rotor arc (F1G1) at point F1. The center of the first female rotor arc (A2B2) is on the connection line between the center O2 of the female rotor and point A2, and the first female rotor arc (A2B2) of the female rotor is tangent to the second female rotor arc (B2C2) of the female rotor at point B2; the second female rotor arc (B2C2) is tangent to the third female rotor arc (C2D2) at point C2; the center of the third female rotor arc (C2D2) is on the connection line of the centers O1 and O2 of the male and female rotors, point D2 is on the connection line of the centers O1 and O2 of the male and female rotors, and is tangent to the female rotor envelope curve (D2E2) at point D2; the female rotor envelope curve (D2E2) is tangent to the fourth female rotor arc (E2F2) at point E2; the center of the fourth female rotor arc (E2F2) is on the connection line between the center O2 of the female rotor and point F2, and the fourth female rotor arc (E2F2) of the female rotor is tangent to the fifth female rotor arc (F2G2) of the female rotor at point F2.

2. The rotor of the steam screw compressor and expander according to claim 1, characterized in that: Taking O1 as the center of the male rotor and O2 as the center of the female rotor to establish a coordinate system, the distance between O1 and O2 is the center distance A between the male rotor and the female rotor. The number of teeth of the male rotor and the female rotor are Z1 and Z2 respectively, and the tooth heights of the male rotor and the female rotor are RC1 and RC2 respectively; the pitch circle radius of the male rotor R1W = A * Z1 / (Z1 + Z2), and the pitch circle radius of the female rotor R2W = A * Z2 / (Z1 + Z2).

3. The rotor of the steam screw compressor and expander according to claim 1, characterized in that: Point G1 of the third male rotor arc (F1G1) makes the angle ∠A1O1G1 satisfy the requirement ∠A1O1G1 = 360° / Z1.

4. The rotor of the steam screw compressor and expander according to claim 1, characterized in that: The point G2 in the fifth female rotor arc (F2G2) makes the angle ∠A2O2G2 satisfy the requirement that ∠A2O2G2 = 360° / Z2.

5. The rotor of the steam screw compressor and expander according to any one of claims 1 to 4, characterized in that: The coordinate equations of the arcs in the male rotor profile and the female rotor profile are as follows: Where x is the abscissa of the profile, in mm; y is the ordinate of the profile, in mm; r is the radius of the arc, in mm; t is the angle of the arc, in degrees; a is the abscissa of the center of the circle corresponding to the arc, in mm; b is the ordinate of the center of the circle corresponding to the arc, in mm.

6. The rotor of the steam screw compressor and expander according to any one of claims 1 to 4, characterized in that: The coordinate equations of the envelope lines in the male rotor profile and the female rotor profile are as follows: Where x is the abscissa of the profile, in mm; y is the ordinate of the profile, in mm; r is the radius of the arc, in mm; t is the angle of the arc, in degrees; A is the center distance, in mm; α is the rotation angle of the profile, in degrees; c1 is the coordinate transformation coefficient from the dynamic coordinates of the male rotor to the static coordinates; c2 is the tooth number ratio of the male rotor to the female rotor; c3 is the coordinate transformation coefficient from the dynamic coordinates of the female rotor to the static coordinates; c4 is the transformation coefficient from the dynamic coordinates of the male rotor to the dynamic coordinates of the female rotor.

7. The rotor of the steam screw compressor and expander according to any one of claims 1 to 4, characterized in that: The arcs and envelope lines in the male rotor profile and the female rotor profile are conjugate curves to each other.

8. The rotor of the steam screw compressor and expander according to any one of claims 2 to 4, characterized in that: The tooth number ratio of the male rotor to the female rotor is 4 - 6:5 - 8.

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