High pressure twin screw compressor double-sided asymmetric rotor profile

Abstract

This invention provides a double-sided asymmetrical rotor profile for a high-pressure twin-screw compressor, comprising a male screw rotor and a female screw rotor. The profiles of the male and female rotor teeth mesh with each other and have the same outer diameter. The tooth profiles of the female rotor teeth sequentially include: female I circular arc, female II circular arc, female III circular arc, female I elliptical arc, female circular arc envelope, female IV circular arc, female II elliptical arc, female straight line, and female V circular arc. The tooth profiles of the male rotor teeth sequentially include: male I circular arc, male I circular arc envelope, male II circular arc envelope, male I elliptical arc envelope, male II circular arc, male III circular arc, male II elliptical arc envelope, male straight line envelope, and male III circular arc envelope. This invention's tooth profile is easy to grind, achieving higher surface accuracy. It features a short contact line, wide sealing surface, small leakage triangle, and small pressure difference between working chambers, improving sealing performance, reducing noise and vibration of the main unit, and increasing the lifespan and long-term operational reliability of the main unit bearings.

Description

Technical Field

[0001] This invention belongs to the technical field of high-pressure twin-screw compressors, specifically relating to a double-sided asymmetric rotor profile for a high-pressure twin-screw compressor. Background Technology

[0002] The profile of the twin-screw compressor has undergone roughly three iterations and upgrades.

[0003] The first-generation profile was a single-sided symmetrical circular arc profile, composed entirely of circular arcs. The first-generation profile solved the problem of going from nothing to something, but the circular arc profile determined that it had a very large leakage triangle, and the main engine efficiency was very low when using oil injection. It has now been completely phased out.

[0004] The second-generation profile is a single-sided asymmetrical profile. Besides circular arcs, its composition includes points, straight lines, and point-generated cycloids. This single-sided asymmetry significantly reduces the leakage triangle, resulting in a more than 10% increase in the main unit's volumetric efficiency. Consequently, the performance of oil-injected screw compressors is significantly improved, and it can also be applied to dry screw compressor applications, leading to rapid development in the screw compressor industry. The second-generation profile requires custom-made milling tools. Because the curve segments are not tangent and contain sharp points, it cannot be machined using currently advanced grinding methods. Currently, it is mainly used in the relatively low-demand dry screw compressor sector.

[0005] The third-generation profile is a single-sided asymmetrical profile, mainly composed of arcs, straight lines, and other curves, eliminating points and point-generated cycloids. This creates a sealing zone between the conjugate curves of the male and female rotors, transforming the rotor tooth surface seal from a line seal to a band seal. This facilitates oil film formation and further enhances the main engine's performance. Furthermore, the third-generation profile allows for grinding, significantly improving the rotor's machining accuracy and efficiency. The third-generation profile is being widely used in the field of oil-injected screw engines, particularly in companies specializing in the production of oil-injected screw engine main engines.

[0006] The second and third generation rotor profiles are both single-sided profiles, still exhibiting relatively large leakage triangles, and are mostly 4-5 or 4-6 teeth. During operation, only 4 working chambers can be formed. The outer circle of the female rotor is generally smaller than that of the male rotor, and the female rotor has more tooth grooves than the male rotor, resulting in low tooth strength and overall low rigidity of the female rotor, as well as large deflection. Furthermore, because the bottom circle of the female rotor is smaller than that of the male rotor, the corresponding shaft diameter at the shaft extension end must also be smaller, and the bearings that can be arranged are also relatively small. This means that it can only be used in operating conditions with exhaust pressure below 1.0MPa. When the exhaust pressure is forcibly increased to above 1.2MPa, the pressure difference between the working chambers increases, and leakage becomes very serious, especially in the last working chamber, where the pressure difference reaches about 0.8MPa. The main unit efficiency is very low, and the bearing load capacity is insufficient, resulting in a very short lifespan. The large rotor deflection also frequently causes the rotor to rub against the casing or even seize.

[0007] Currently, the demand for high-pressure screw compressors in the market is not only increasing, but in order to achieve higher exhaust pressure, it is necessary to adopt a multi-stage compression method with multiple screw compressors in series or a screw and piston series compression method to respond to the market.

[0008] With the rapid development of screw compressor companies, they are actively exploring the composition of fourth-generation profiles. In addition to considering factors such as profile contact line length, leakage triangle size, closed volume size, area utilization coefficient, meshing clearance, tooth tip clearance, exhaust clearance, and internal pressure ratio, they also need to consider the cost of profile development, processing efficiency, processing accuracy, ease of measurement, as well as factors such as increased exhaust pressure, long-term operational stability, and parts versatility. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a double-sided asymmetrical rotor profile for a high-pressure twin-screw compressor. The specific technical solution is as follows:

[0010] The high-pressure twin-screw compressor has a double-sided asymmetrical rotor profile, including a male screw rotor and a female screw rotor. The end section of the male screw rotor includes a male bottom circle, a male pitch circle, and a male outer circle, with the male rotor teeth located between the male bottom circle and the male outer circle. The end section of the female screw rotor includes a female bottom circle, a female pitch circle, and a female outer circle, with the female rotor teeth located between the female bottom circle and the female outer circle.

[0011] The male and female pitch circles are tangent to each other. The tooth profiles of the male and female rotor teeth are distributed on both sides of the tangent line of the male and female pitch circles, respectively. The profiles mesh with each other and have the same outer diameter.

[0012] The tooth profile of the female rotor tooth includes the following profile segments in sequence: a female I circular arc, a female II circular arc, a female III circular arc, a female I elliptical arc, a female circular arc envelope, a female IV circular arc, a female II elliptical arc, a female straight line, and a female V circular arc;

[0013] The tooth profile of the male rotor tooth includes the following profile segments in sequence: a section of male I circular arc, a section of male I circular arc envelope, a section of male II circular arc envelope, a section of male I circular arc envelope, a section of male II circular arc, a section of male III circular arc, a section of male II elliptical arc envelope, a section of male straight line envelope, and a section of male III circular arc envelope.

[0014] The male rotor teeth and female rotor teeth have 6 and 8 teeth respectively.

[0015] Each type of line segment has a certain length and is tangent at the intersection point, with a smooth transition.

[0016] The outer diameters of the yang and yin outer circles are the same.

[0017] The contact position on the drive side of the tooth profile uses an elliptical arc and an elliptical arc envelope, while the sealing line position on the sealing side uses an elliptical arc and an elliptical arc envelope.

[0018] This type of line can be applied to working applications where the single-stage compression exhaust pressure is between 1.2 and 3.0 MPa.

[0019] The present invention has the following technical effects:

[0020] The invention features smooth transitions at the intersections of all tooth profile segments, facilitating high-speed grinding and achieving higher surface accuracy. This not only improves the processing efficiency of the rotor but also enhances the mechanical efficiency of the main unit. Furthermore, the smooth surface reduces airflow disturbance, lowers noise and vibration of the main unit, and improves product stability and reliability.

[0021] The invention features profile segments on both the inner and outer sides of the pitch circle, with the profile being asymmetrical on both sides. Elliptical arcs and their envelopes are used at the contact points on the drive side and the sealing line on the sealing side. For the same central angle, the ellipse has a longer arc length than a circle, thus widening the contact and sealing zones and reducing the leakage triangle. This results in relatively smaller contact forces on the drive side of the tooth surface in high-pressure applications, preventing tooth surface wear. Simultaneously, a wider, more uniformly thick oil film is more easily formed on the sealing side, sealing off higher-pressure gases, reducing leakage, improving the efficiency of the main unit, and achieving higher energy efficiency.

[0022] The invention employs 6 or 8 teeth to form 6 intake chambers and 6 compression chambers, which greatly reduces the pressure difference between the working chambers. At the same time, the contact line between the working chambers is shortened, reducing leakage between the working chambers. In high-pressure applications, the efficiency of the main unit is significantly improved.

[0023] The invention features male and female rotors with the same outer diameter and closer linear velocities at the rotor teeth, which improves the rigidity and sealing performance of the female rotor. The increased side shaft diameter of the female rotor allows for the configuration of larger bearings to withstand greater axial and radial gas forces. In high-pressure applications, the rigidity of the rotor, the lifespan of the bearings, and the long-term reliability of the main unit are all guaranteed.

[0024] The tooth profile of this invention can be used in both high-pressure twin-screw compressors and atmospheric-pressure twin-screw compressors. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the tooth profile structure of the present invention. Detailed Implementation

[0027] The technical solution of the present invention is illustrated with reference to the accompanying drawings, using the example of male and female rotors both having an outer diameter of 140 mm.

[0028] like Figure 1 and Figure 2As shown, the high-pressure twin-screw compressor has a double-sided asymmetrical rotor profile, including a male screw rotor 1 and a female screw rotor 2. In this embodiment, the male screw rotor 1 is a six-head screw and the female screw rotor 2 is an eight-head screw.

[0029] The end section of the male screw rotor 1 includes a male bottom circle 11 with a diameter of 92.4 mm, a male pitch circle 12 with a diameter of 96 mm, and a male outer circle 13 with a diameter of 140 mm. The male rotor teeth 14 are located between the male bottom circle 11 and the male outer circle 13. The end section of the female screw rotor 2 includes a female bottom circle 21 with a diameter of 92.4 mm, a female pitch circle 22 with a diameter of 128 mm, and a female outer circle 23 with a diameter of 140 mm. The female rotor teeth 24 are located between the female bottom circle 21 and the female outer circle 23. The male outer circle 13 and the female outer circle 23 have the same diameter, which is 140 mm.

[0030] The profiles of male rotor teeth 14 and female rotor teeth 24 mesh with each other and have the same outer diameter, both being 140mm.

[0031] The tooth profile of the female rotor tooth 24 includes the following line segments in sequence: a female arc I a2-b2 with a radius of 70mm concentric with the female pitch circle 22; a female arc II b2-c2 with a radius of 6mm centered at o1 on the female pitch circle 22; a female arc III c2-d2 with a radius of 50mm centered at o2 on the female pitch circle 22 and tangent to the arc b2-c2; and a female elliptical arc I d2-e2 with a maximum radius of curvature of 29.4mm and a minimum radius of curvature of 6.4mm, which is tangent to both arc c2-d2 and the arc envelope e2-f2. A segment of the envelope line e2-f2 formed by the arc segment e1-f1 of the male rotor tooth profile; a segment of the arc f2-g2 of the female IV with the external tangent point P of the female pitch circle 22 and the male pitch circle 12 as the center and a radius of 22mm; a segment of the elliptical arc g2-h2 of the female II with the minimum radius of curvature point g2, a maximum radius of curvature of 51.5mm, and a minimum radius of curvature of 14mm; a segment of the straight line h2-i2 of the female II that is tangent to the elliptical arc g2-h2 and the arc i2-j2; and a segment of the arc i2-j2 of the female V with the center o6 on the female pitch circle 22 and a radius of 6mm.

[0032] The tooth profile of the male rotor tooth 14 includes the following profile segments in sequence: a male I circular arc a1-b1 with a radius of 46.2mm concentric with the male pitch circle 12; a male I circular arc envelope b1-c1 formed by the female rotor tooth profile b2-c2 circular arc segment; a male II circular arc envelope c1-d1 formed by the female rotor tooth profile c2-d2 circular arc segment; a male I elliptical arc envelope d1-e1 formed by the female rotor tooth profile d2-e2 elliptical arc segment; and a segment with o3 as... The center consists of a yang II circular arc e1-f1 with a radius of 16mm, a yang III circular arc f1-g1 with a radius of 22mm centered at the external tangent point P of the yin and yang joint circles 22 and 12, a yang II elliptical arc envelope g1-h1 formed by the yin rotor tooth profile g2-h2, a yang straight line envelope h1-i1 formed by the yin rotor tooth profile h2-i2, and a yang III circular arc envelope i1-j1 formed by the yin rotor tooth profile i2-j2.

[0033] Furthermore, the male rotor tooth 14 and the female rotor tooth 24 have 6 and 8 teeth respectively.

[0034] Each type of line segment has a certain length and is tangent at the intersection point, with a smooth transition.

[0035] Each screw has the same profile and is evenly distributed around its circumference; the six-head and eight-head screws are arranged in parallel and mesh with each other, with a center distance of 112mm between the male and female rotors. Its advantages include good meshing performance, ease of implementation of the latest grinding processes, short contact line, wide sealing surface, small leakage triangle, good sealing performance, large area utilization coefficient, high volumetric efficiency, and good specific power of the main unit. It also solves the problems of severe leakage in the working chamber, low main unit efficiency, and high failure rate in high-pressure applications.

Claims

1. A high-pressure twin-screw compressor with a double-sided asymmetrical rotor profile, characterized in that, The system includes a male screw rotor (1) and a female screw rotor (2). The end section of the male screw rotor (1) includes a male bottom circle (11), a male pitch circle (12), and a male outer circle (13). The male rotor teeth (14) are located between the male bottom circle (11) and the male outer circle (13). The end section of the female screw rotor (2) includes a female bottom circle (21), a female pitch circle (22), and a female outer circle (23). The female rotor teeth (24) are located between the female bottom circle (21) and the female outer circle (23). The male pitch circle (12) and the female pitch circle (22) are tangent to each other. The tooth profiles of the male rotor teeth (14) and the female rotor teeth (24) are distributed on both sides of the tangent lines of the male pitch circle (12) and the female pitch circle (22), respectively, meshing with each other and having the same outer diameter. The tooth profile of the female rotor tooth (24) includes the following line segments in sequence: a female I circular arc (a2-b2), a female II circular arc (b2-c2), a female III circular arc (c2-d2), a female I elliptical arc (d2-e2), a female circular arc envelope (e2-f2), a female IV circular arc (f2-g2), a female II elliptical arc (g2-h2), a female straight line (h2-i2), and a female V circular arc (i2-j2); The tooth profile of the male rotor tooth (14) includes the following profile segments in sequence: a section of male I circular arc (a1-b1), a section of male I circular arc envelope (b1-c1), a section of male II circular arc envelope (c1-d1), a section of male I elliptical arc envelope (d1-e1), a section of male II circular arc (e1-f1), a section of male III circular arc (f1-g1), a section of male II elliptical arc envelope (g1-h1), a section of male straight line envelope (h1-i1), and a section of male III circular arc envelope (i1-j1); Each type of line segment has a set length and is tangent at the intersection point, with a smooth transition; The outer diameters of the male outer circle (13) and the female outer circle (23) are the same; The contact position on the drive side of the tooth profile adopts an elliptical arc (g2-h2) and an elliptical arc envelope (g1-h1), while the sealing line position on the sealing side adopts an elliptical arc (d2-e2) and an elliptical arc envelope (d1-e1). The tooth profiles described above have smooth transitions at their intersections, making them easy to process with high-speed grinding, achieving higher surface accuracy, improving the rotor's processing efficiency, and also improving the mechanical efficiency of the main unit. At the same time, the smooth surface reduces airflow disturbance, lowers the noise and vibration of the main unit, and improves the stability and reliability of the product. The aforementioned tooth profile has profile segments on both the inner and outer sides of the pitch circle. The tooth profile is asymmetrical with double sides, and elliptical arcs and elliptical arc envelopes are used at the contact position on the drive side and the sealing line position on the sealing side. For the same central angle, the ellipse has a longer arc length than the circle, which widens the contact and sealing bands, reduces the leakage triangle, and makes the contact force on the drive side of the tooth surface relatively small in high-pressure applications, avoiding tooth surface wear. At the same time, it is easier to form a wider and more uniform oil film on the sealing side, which can seal higher pressure gases, reduce leakage, improve the efficiency of the main unit, and achieve higher energy efficiency. The aforementioned toothed male and female rotors have the same outer diameter and closer tooth tip linear velocities, which improves the rigidity and sealing performance of the female rotor. The increased side shaft diameter of the female rotor allows for the configuration of larger bearings to withstand greater axial and radial gas forces. In high-pressure applications, the rigidity of the rotor, the lifespan of the bearings, and the long-term reliability of the main unit are all guaranteed.

2. The high-pressure twin-screw compressor with double-sided asymmetrical rotor profile according to claim 1, characterized in that: The number of teeth of the male rotor tooth (14) and the female rotor tooth (24) are 6 and 8, respectively.

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