An elliptical intermeshing twin screw compressor rotor and a design method thereof

Abstract

An elliptical internal meshing twin-screw compressor rotor and its design method are disclosed. The inner rotor profile adopts a fully elliptical structure, and the outer rotor profile adopts an elliptical envelope. After guiding the profiles of the inner and outer rotors with a helix, the complete outlines of the inner and outer rotors are generated respectively. Through the coordinated rotation of the inner and outer rotors, the volume of the internal cavity changes periodically, achieving a forced gas transport effect. The design method includes optimizing the center distance of the inner and outer rotors, the major axis length of the inner rotor's elliptical profile, and the lead of the inner rotor's guiding helix based on the volume and pumping speed; optimizing the helix angle of the inner rotor based on gas sealing requirements and stress performance requirements; solving for the inner and outer rotor profiles using the optimized parameters; obtaining the helix lead and helix angle of the outer rotor; and forming the complete outlines of the inner and outer rotors by scanning the inner and outer rotor profiles with the helix guide. This invention improves space utilization and avoids leakage channels between the rotor and the casing.

Description

Technical Field

[0001] This invention belongs to the field of rotor processing, specifically relating to an elliptical internal meshing twin-screw compressor rotor and its design method. Background Technology

[0002] A twin-screw compressor is a positive displacement rotary compressor used to obtain high-pressure gases and has wide applications in modern industry. It inherits many advantages of rotary machinery, such as long service life, reliable operation, low vibration, low noise, smooth operation, and no surge. It also features the absence of easily damaged parts like valves, forced suction and discharge, and simple manufacturing, making it a core component in air supply, refrigeration, and waste heat recovery systems. Currently, for ease of manufacturing, the rotor meshing relationship of commonly used twin-screw compressors is external meshing. This results in a large center distance between the rotors and a long leakage line length, thus reducing space utilization and increasing leakage intensity, ultimately preventing the miniaturization of current screw rotors. Summary of the Invention

[0003] The purpose of this invention is to address the problems of low rotor space utilization and leakage channels in the existing twin-screw compressor technology, and to provide an elliptical internal meshing twin-screw compressor rotor and its design method. By improving the rotor space utilization through internal meshing, leakage channels between the rotor and the casing are avoided, thereby achieving miniaturization of the twin-screw compressor.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] An elliptical internal meshing twin-screw compressor rotor, wherein the profile of the inner rotor adopts a fully elliptical structure and the profile of the outer rotor adopts an elliptical envelope, and the inner and outer rotors conform to a non-interfering meshing relationship.

[0006] After the profiles of the inner and outer rotors are guided by a helical line, the complete outlines of the inner and outer rotors are generated respectively. Through the coordinated rotation of the inner and outer rotors, the volume of the internal cavity changes periodically, thereby achieving the effect of forced gas transport.

[0007] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the complete outline of the inner rotor is formed by scanning the inner rotor profile with a helix with a lead of L1 as the guide line, and the complete outline of the outer rotor is formed by scanning the outer rotor profile with a helix with a lead of L2 as the guide line; the inner and outer rotors rotate around their respective central axes at angular velocities ω1 and ω2 respectively, which can complete the meshing operation without interference and realize the operation of the basic volume cavity from the intake end face to the exhaust end face.

[0008] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the angular velocities ω1 and ω2 of the inner and outer rotors satisfy the following conditions:

[0009] 3ω2=2ω1.

[0010] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the helix leads L1 and L2 of the inner and outer rotors satisfy the following conditions:

[0011] 2L2 = 3L1.

[0012] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the helix angles γ1 and γ2 of the inner and outer rotors satisfy the following conditions:

[0013] 3γ2=2γ1.

[0014] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the inner rotor profile has 2 rotor teeth, the outer rotor has 3 rotor teeth, and the center distance between the inner and outer rotors is c; the pitch circle radii of the inner and outer rotors are r respectively. p1 With r p2 The major axis of the inner rotor elliptical profile is r1, and the minor axis is r2. The outer rotor profile is obtained from the inner rotor profile equation according to the meshing relationship. The variable parameters of the inner and outer rotor profiles are the center distance c between the inner and outer rotors and the major axis r1 of the inner rotor elliptical profile.

[0015] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the pitch circle radius of the inner and outer rotors and the center distance between the inner and outer rotors satisfy the following relationship:

[0016]

[0017] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the parametric equation of the inner rotor profile A1B1C1D1 is as follows:

[0018]

[0019] The major axis length r1 and minor axis length r2 of the inner rotor's elliptical profile satisfy the following relationship with the center distance c between the inner and outer rotors:

[0020] r2 = r1 + 2c.

[0021] As a preferred embodiment of the elliptical internal meshing twin-screw compressor rotor of the present invention, the parametric equation of the curve segment A2B2 of the outer rotor profile is:

[0022]

[0023] Where β is an intermediate variable, its relationship with θ is determined by the following formula:

[0024]

[0025] This invention also proposes a rotor design method for an elliptical internal meshing twin-screw compressor:

[0026] - The center distance c between the inner and outer rotors is selected based on the volume and pumping speed, the major axis length r1 of the inner rotor elliptical profile, and the helical lead L1 that guides the inner rotor profile to scan the complete outline of the rotor.

[0027] - The helix angle γ1 of the inner rotor is selected based on the requirements for gas sealing and stress performance;

[0028] - Solve for the inner and outer rotor profiles using optimized parameters;

[0029] - Obtain the helical lead L2 and helical angle γ2 of the outer rotor;

[0030] - The complete outline of the inner and outer rotors is formed by scanning with a helix guided by the inner and outer rotor profiles.

[0031] Compared to existing technologies, this invention offers the following advantages: The elliptical internally meshing twin-screw compressor rotor adopts an internally meshing twin-screw rotor profile, making the two rotors more compact. It also eliminates the need for a housing to create a sealed working volume cavity, avoiding the leakage area between the rotor teeth and the housing, which is beneficial for improving rotor thermal performance. The rotor structure of this invention enables gas pressurization and transportation in the screw compressor, improving space utilization and preventing leakage channels between the rotor and the housing. This improves the volumetric efficiency, adiabatic efficiency, and stress performance of the twin-screw compressor, making miniaturization of the twin-screw compressor possible. Compared to other conventional pump types, the compressor using this invention has advantages such as fewer vulnerable parts, a compact structure, high pumping speed, no surge, and low vibration and noise. Attached Figure Description

[0032] Figure 1 A schematic diagram of the profile structure of the elliptical internal meshing twin-screw compressor rotor of the present invention;

[0033] Figure 2 A schematic diagram illustrating the changing process of the meshing relationship between the inner and outer rotor profiles in this invention;

[0034] Figure 3 A cross-sectional view of the assembly structure of the elliptical internal meshing twin-screw compressor rotor of the present invention;

[0035] Figure 4 A schematic diagram illustrating the working process of the inner and outer rotors of this invention;

[0036] Figure 5Schematic diagrams of the inner and outer rotor profiles under different parameters of the present invention: (a) r1 = 3c; (b) r1 = 4c; (c) r1 = 5c; (d) r1 = 6c; (e) r1 = 7c; (f) r1 = 8c. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0038] like Figure 1 As shown, this invention designs the inner rotor profile as a fully elliptical structure (curve A1B1C1D1), and the outer rotor profile as an envelope structure of this elliptical structure (curve A2B2C2D2). Figure 2 As shown, the inner and outer rotor profiles can achieve the correct meshing relationship. For example... Figure 3 As shown, by guiding the inner and outer rotor profiles with a helical line, inner and outer rotors can be generated separately. For example... Figure 4 As shown, the coordinated rotation of the inner and outer rotors enables periodic changes in the volume of the internal cavity, achieving a forced gas transport effect. Figure 5 As shown, the inner and outer rotor profiles designed in this invention can achieve flexible shape adjustment.

[0039] exist Figure 1 In the design, the inner rotor profile has 2 rotor teeth, the outer rotor has 3 rotor teeth, and the center distance between the inner and outer rotors is c. The pitch circle radii of the inner and outer rotors are r and r, respectively. p1 With r p2 The major axis of the inner rotor's elliptical profile is r1, and the minor axis is r2. The outer rotor profile can be obtained from the inner rotor profile equation based on the meshing relationship. The variable parameters of the inner and outer rotor profiles are the center distance c between the inner and outer rotors and the major axis r1 of the inner rotor's elliptical profile. Figure 2 It is evident that the inner and outer rotor profiles can achieve interference-free meshing.

[0040] exist Figure 3 and Figure 4 In this system, the inner rotor is formed by scanning the inner rotor profile with a helix of lead L1 as the guide line, and the outer rotor is formed by scanning the outer rotor profile with a helix of lead L2 as the guide line. The inner and outer rotors rotate at angular velocities ω1 and ω2 respectively along their respective axes, enabling interference-free meshing operation and realizing the movement of the basic volume chamber from the intake end face to the exhaust end face.

[0041] like Figure 5 As shown, the shape of the profile can be controlled by the ratio of the major axis length r1 of the inner rotor elliptical profile to the center distance c between the inner and outer rotors.

[0042] The relationship between the pitch circle radius and the center distance of the inner and outer rotors is as follows:

[0043]

[0044] The parametric equation for the inner rotor profile ellipse curve A1B1C1D1 is:

[0045]

[0046] The major axis length r1, minor axis length r2 of the inner rotor's elliptical profile and the center distance c between the inner and outer rotors satisfy the following relationship:

[0047] r2 = r1 + 2c

[0048] The parametric equation for curve segment A2B2 of the outer rotor profile is:

[0049]

[0050] Where β is an intermediate variable, its relationship with θ is solved according to the following equation:

[0051]

[0052] The angular velocities ω1 and ω2 of the inner and outer rotors satisfy the following condition:

[0053] 3ω2=2ω1

[0054] The leads L1 and L2 of the guiding helices of the inner and outer rotors satisfy the following conditions:

[0055] 2L2 = 3L1

[0056] The helical angles γ1 and γ2 of the inner and outer rotors satisfy the following conditions:

[0057] 3γ2=2γ1

[0058] The independent variables in the above solution process are: profile independent variables (major axis length r1 of the inner rotor elliptical profile, center distance c between the inner and outer rotors) and guide line independent variables (lead L1 and rotation angle γ1 of the inner rotor guide helix). By changing the proportional relationship between the major axis length r1 of the inner rotor elliptical profile and the center distance c between the inner and outer rotors, the following can be obtained: Figure 5 The internally meshing twin-screw rotor profile is shown. It can be seen that because the rotor structure designed in this invention uses an internally meshing twin-screw rotor profile, the two rotors are more compact, and a closed working volume cavity can be achieved without a shell. This avoids the leakage area between the tooth tips of the externally meshing twin-screw rotor and the shell, thereby improving the rotor's thermal performance.

[0059] A method for designing an elliptical internal meshing twin-screw compressor rotor, the design process of which is as follows:

[0060] 1. The optimal center distance c between the inner and outer rotors, the major axis length r1 of the inner rotor's elliptical profile, and the lead L1 of the helix guiding the inner rotor profile to scan the complete rotor contour are determined by the optimal size and pumping speed. Figure 1 As shown, the center distance c between the inner and outer rotor profiles is 3mm, the major axis length r1 of the inner rotor profile ellipse is 13mm, and the lead L1 of the inner rotor helix is ​​20mm.

[0061] 2. Based on the requirements for gas sealing and stress performance, the inner rotor helix angle γ1 is preferably 648°.

[0062] 3. Solve for the rotor profile using the above-mentioned optimized parameters;

[0063] The inner rotor profile ellipse curve A1B1C1D1 is determined using the following formula:

[0064]

[0065] The elliptic curve A2B2C2D2 of the outer rotor profile is determined using the following formula:

[0066]

[0067] The relationship between β and θ is solved using the meshing theorem:

[0068]

[0069] Thus, the inner and outer rotor profiles were determined.

[0070] 4. Using the above-mentioned optimized parameters, the helical guide lines of the inner and outer rotors are obtained. The lead of the inner rotor's guide helix is ​​L1, and the rotation angle is γ1. The lead of the outer rotor's guide helix is ​​L2, and the rotation angle is γ2. These are obtained using the following formula:

[0071]

[0072] The inner and outer rotor structures are formed by scanning the rotor helical guide lines using the inner and outer rotor profiles obtained above.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. An elliptical internal meshing twin-screw compressor rotor, characterized in that: The profile of the inner rotor adopts a fully elliptical structure, while the profile of the outer rotor adopts an elliptical envelope. The inner and outer rotors conform to a non-interfering meshing relationship. After the profiles of the inner and outer rotors are guided by a helical line, the complete outlines of the inner and outer rotors are generated respectively; through the coordinated rotation of the inner and outer rotors, the volume of the internal cavity changes periodically, thereby achieving the effect of forced gas transport. The complete profile of the inner rotor is determined by the inner rotor profile with a lead of L The helix of 1 is formed by scanning the guide line, and the complete profile of the outer rotor is formed by the outer rotor profile with a lead of 1. L The helix of 2 is formed by scanning the guide line; the inner and outer rotors revolve around their respective central axes at angular velocities. ω 1 and ω 2. Rotation enables interference-free meshing operation, allowing the basic volume chamber to move from the intake end face to the exhaust end face; angular velocity of inner and outer rotors ω 1 and ω 2. The following conditions must be met: Helical lead of inner and outer rotors L 1 and L 2. The following conditions must be met: Helical angle of inner and outer rotors γ 1 and γ 2. The following conditions must be met: The inner rotor profile has 2 rotor teeth, the outer rotor has 3 rotor teeth, and the center distance between the inner and outer rotors is... c The pitch circle radii of the inner and outer rotors are respectively r p1 and r p2 The major axis of the inner rotor's elliptical profile is... r 1. The length of the minor axis is r 2; The outer rotor profile is obtained from the inner rotor profile equation based on the meshing relationship; The variable parameter of the inner and outer rotor profiles is the center distance between the inner and outer rotors. c and the major axis length of the inner rotor elliptical profile r 1; The pitch circle radii of the inner and outer rotors and the center distance between the inner and outer rotors satisfy the following relationship: Internal rotor profile The parametric equation is: ； Major axis length of the inner rotor elliptical profile r 1. Short axis length r 2. Center distance between the inner and outer rotors c The following relationship must be satisfied: Curved section of the outer rotor profile The parametric equation is: ； in, β As an intermediate variable, and θ The relationship is solved using the following formula: 。

Images