A segmented variable cross-section screw rotor

Abstract

The invention discloses a segmented variable cross-section screw rotor, wherein a left-handed screw rotor (100) and a right-handed screw rotor (200) are arranged in segments and can achieve correct meshing; the pitch of the screw rotor changes continuously in segments, and the cross-sectional profile changes continuously in segments, but each cross-sectional profile is composed of five segments of curves connected end to end, and the type remains unchanged; from the first axial position Ⅰ-Ⅰ to the ninth axial position Ⅸ-Ⅸ, the area utilization coefficient of the cross-sectional profile of the two screw rotors gradually increases, the formed working chamber volume gradually increases, and the center distance remains unchanged; the tooth width of the two screw rotors on the suction side is smaller, and the tooth width of the two screw rotors on the exhaust side is larger, and good interstage sealing performance is provided; the proposed segmented variable cross-section screw rotor has a larger pumping speed, a higher ultimate vacuum degree and an internal volume ratio under the same axial length, and has a wider scope and field of application.

Description

Technical Field

[0001] The invention relates to a twin-screw vacuum pump, in particular to a segmented variable-section screw rotor suitable for the twin-screw vacuum pump. Background Art

[0002] The twin-screw vacuum pump is a dry oil-free vacuum pump with the characteristics of compact structure, stable operation and wide application range. It is widely used in the fields of semiconductor, chemical industry, food and medicine. The core component of the twin-screw vacuum pump is a pair of intermeshing screw rotors. The characteristics of the screw rotors determine the performance of the twin-screw vacuum pump. Driven by the synchronous gears, the screw rotors rotate in opposite directions in the pump chamber, thereby completing the process of gas suction, pressurization and discharge, and achieving the purpose of vacuum extraction. The tooth width, pitch change mode and area utilization of the screw rotor directly determine the pumping speed, internal volume ratio and ultimate vacuum degree of the twin-screw vacuum pump.

[0003] The Chinese patent, publication number CN105971877A, discloses a conical screw rotor and a twin-screw vacuum pump thereof; its characteristics are: the two screw rotors of the twin-screw vacuum pump are segmented, and the volume of the working chamber changes gradually, but the tooth width on the suction side is too large, the area utilization rate is not large enough, the suction volume is not large enough, and the tooth width on the exhaust side is too small, and the interstage sealing performance is not high enough; thus, the pumping speed of the twin-screw vacuum pump is reduced, the internal volume ratio is not high enough, and the ultimate vacuum degree is reduced. Summary of the invention

[0004] In order to maximize the pumping speed, internal volume ratio and ultimate vacuum degree of a twin-screw vacuum pump, the present invention proposes a segmented variable-section screw rotor, comprising a left-handed screw rotor (100) and a right-handed screw rotor (200); from the first axial position I-I to the ninth axial position IX-IX, the two screw rotors are arranged in segments, each cross-sectional profile changes continuously, and the area utilization coefficient gradually increases, but each cross-sectional profile is composed of five segments of curves connected end to end and of the same type; from the first axial position I-I to the ninth axial position IX-IX, the working chamber volume formed by the two screw rotors gradually increases, and the maximum working chamber volume is formed on the suction side; the two screw rotors have a smaller tooth width on the suction side and a larger tooth width on the exhaust side, and have good inter-stage sealing performance; the proposed segmented variable-section screw rotor is of great significance for expanding the scope and field of application of the twin-screw vacuum pump and improving the working performance of the twin-screw vacuum pump.

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

[0006] A segmented variable cross-section screw rotor comprises: a left-handed screw rotor (100) and a right-handed screw rotor (200); from a first axial position I-I to a ninth axial position IX-IX, the left-handed screw rotor (100) is segmented: from the first axial position I-I to the fifth axial position V-V is a left-handed equal pitch section (101), from the fifth axial position V-V to the seventh axial position VII-VII is a left-handed conical section (102), from the seventh axial position VII-VII to the ninth axial position IX-IX is a left-handed variable pitch section (103); the right-handed screw rotor (200) is arranged in sections: from the first axial position I-I to the fifth axial position V-V is a right-handed equal pitch section (201), from the fifth axial position V-V to the seventh axial position VII-VII is a right-handed conical section (202), from the seventh axial position VII-VII to the ninth axial position IX-IX is a right-handed variable pitch section (203); from the first axial position I-I to the ninth axial position IX-IX, the cross-sectional profiles of the left-handed screw rotor (100) change continuously, and the area utilization coefficient gradually increases. The left-handed equal pitch section (101) has a tooth top width that gradually decreases, and the pitch changes in a constant pitch manner; the left-handed conical section (102) is linearly conical, with a tooth top width that gradually decreases, and the pitch changes in a variable pitch manner, and the pitch gradually increases; the left-handed variable pitch section (103) has a tooth top width that gradually decreases, and the pitch changes in a variable pitch manner, and the pitch gradually increases; a left-handed equal pitch section (101) and a left-handed variable pitch section (103) are connected to each other. The invention discloses a right-hand screw rotor (200) and a left-hand screw rotor (100). The right-hand screw rotor (200) and the left-hand screw rotor (100) are connected to each other through a transitional conical section (102). At the fifth axial position V-V, the cross-sectional profile of the left-hand equal pitch section (101) and the left-hand conical section (102) are the same; at the seventh axial position VII-VII, the cross-sectional profile of the left-hand conical section (102) and the left-hand variable pitch section (103) are the same; from the first axial position I-I to the ninth axial position IX-IX, the center distance between the right-hand screw rotor (200) and the left-hand screw rotor (100) remains unchanged, so that correct meshing can be achieved, and the volume of the formed working chamber gradually increases.

[0007] A segmented variable cross-section screw rotor, wherein a spiral expansion angle τ changes continuously from 0 to 8π from a first axial position Ⅰ-Ⅰ to a ninth axial position IX-IX; at the first axial position Ⅰ-Ⅰ, the spiral expansion angle τ=0; at the fifth axial position Ⅴ-Ⅴ, the spiral expansion angle τ=4π; at the seventh axial position Ⅶ-Ⅶ, the spiral expansion angle τ=6π; at the ninth axial position Ⅸ-Ⅸ, the spiral expansion angle τ=8π; as the spiral expansion angle τ changes from 0 to 8π, the pitch P(τ) of the left-handed screw rotor (100) changes as follows: from the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the pitch P(τ) of the left-handed equal pitch section (101) remains unchanged and satisfies:

[0008]

[0009] Where, L1 is the rotor length of the left-handed equal pitch section (101);

[0010] From the seventh axial position VII-VII to the ninth axial position IX-IX, the pitch P (τ) of the left-handed variable pitch section (103) gradually increases and satisfies:

[0011]

[0012] Wherein, α is the variable pitch coefficient of the left-hand variable pitch section (103); L 3 is the rotor length of the left-hand variable pitch section (103);

[0013] From the fifth axial position V-V to the seventh axial position VII-VII, the pitch P (τ) of the left-handed conical section (102) gradually increases and satisfies:

[0014]

[0015] Where, L 2 is the rotor length of the left-handed conical section (102);

[0016] As the spiral expansion angle τ changes from 0 to 8π, the axial length Z(τ) of the left-handed screw rotor (100) changes as follows:

[0017]

[0018] At the same axial position, the pitch p(τ) of the right-handed screw rotor (200) and the pitch P(τ) of the left-handed screw rotor (100) are equal, and the spiral directions are opposite.

[0019] A segmented variable cross-section screw rotor, wherein the left-handed cross-section profile (1001) of the left-handed screw rotor (100) is composed of a left-handed tooth tip arc AB, a left-handed circular involute BC, a left-handed first cycloid CD, a left-handed tooth root arc DE and a left-handed second cycloid EA; as the spiral expansion angle τ increases from 0 to 8π, the radius R of the left-handed tooth tip arc AB of the left-handed cross-section profile (1001) increases. 1 The variation law of (τ) is as follows: from the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the radius R of the left-handed tooth top arc AB is 1 (τ) remains unchanged and satisfies:

[0020] R 1 (τ) = R 1a , 0≤τ<4π

[0021] In the formula, R 1a is the initial radius of the left-handed tooth tip arc AB at the first axial position Ⅰ-Ⅰ;

[0022] From the seventh axial position VII-VII to the ninth axial position IX-IX, the radius R of the left-handed tooth top arc AB 1 (τ) remains unchanged and satisfies:

[0023] R 1 (τ) = R 1c , 6π≤τ≤8π

[0024] In the formula, R 1c is the initial radius of the left-handed tooth tip arc AB at the seventh axial position VII-VII;

[0025] From the fifth axial position V-V to the seventh axial position VII-VII, the radius R of the left-handed tooth top arc AB 1 (τ) increases linearly with the axial length Z(τ) and satisfies:

[0026]

[0027] As the helix expansion angle τ increases from 0 to 8π, the radius R of the left-hand tooth root arc DE 3 The changing rule of (τ) is:

[0028] R 3 (τ) = mR 1 (τ), 0≤τ≤8π

[0029] Wherein, m is the center distance between the left-handed screw rotor (100) and the right-handed screw rotor (200);

[0030] As the helix expansion angle τ increases from 0 to 8π, the base circle radius R of the left-handed circular involute BC 4 The changing rule of (τ) is:

[0031] From the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the base circle radius R of the left-handed circular involute BC 4 (τ) gradually increases, R 4 The absolute value of the first-order derivative of (τ) gradually increases and satisfies:

[0032]

[0033] In the formula, R 4a is the initial base circle radius of the left-handed circular involute BC at the first axial position Ⅰ-Ⅰ; R 4b k is the initial base circle radius of the left-handed circular involute BC at the fifth axial position V-V; 1 is the variable base circle coefficient of the left-handed equal pitch segment (101);

[0034] From the seventh axial position VII-VII to the ninth axial position IX-IX, the base circle radius R of the left-handed circular involute BC 4 (τ) gradually increases, R4 The absolute value of the first-order derivative of (τ) gradually decreases and satisfies:

[0035]

[0036] In the formula, R 4c is the initial base circle radius of the left-handed involute BC at the seventh axial position Ⅶ-Ⅶ; R 4d k is the initial base circle radius of the left-handed involute BC at the ninth axial position IX-IX; 2 is the variable base circle coefficient of the left-hand variable pitch section (103);

[0037] From the fifth axial position V-V to the seventh axial position VII-VII, the base circle radius R of the left-handed circular involute BC 4 (τ) gradually increases, R 4 The absolute value of the first-order derivative of (τ) remains unchanged and satisfies:

[0038]

[0039] A segmented variable cross-section screw rotor, wherein the right-handed cross-section profile (2001) of the right-handed screw rotor (200) is composed of a right-handed tooth top arc ab, a right-handed circular involute bc, a right-handed first cycloid cd, a right-handed tooth root arc de and a right-handed second cycloid ea; at the same axial position, the radius r of the right-handed tooth top arc ab is 1 (τ) and the radius R of the left-handed tooth tip arc AB 1 (τ) is equal, the pitch radius r of the right-handed cross-section profile (2001) 2 and the pitch radius R of the left-handed section profile (1001) 2 Equal and satisfy: r 2 +R 2 =m, the radius r of the right-hand tooth root arc de 3 (τ) and the radius R of the left-hand tooth root arc DE 3 (τ) is equal, the base circle radius r of the right-handed circular involute bc 4 (τ) and the base circle radius R of the left-handed circular involute BC 4 (τ) are equal.

[0040] A segmented variable cross-section screw rotor, wherein at the same axial position, a right-handed tooth tip arc ab, a right-handed circular involute bc, a right-handed first cycloid cd, a right-handed tooth root arc de and a right-handed second cycloid ea of ​​a right-handed cross-sectional profile (2001) can be correctly meshed with a left-handed tooth root arc DE, a left-handed circular involute BC, an upper end point B of a left-handed tooth tip arc AB, a left-handed tooth tip arc AB and a lower end point A of a left-handed tooth tip arc AB of a left-handed cross-sectional profile (1001).

[0041] The beneficial effects of the present invention are:

[0042] ① A segmented variable-section screw rotor is proposed, from the first axial position Ⅰ-Ⅰ to the ninth axial position Ⅸ-Ⅸ, the two screw rotors are arranged in sections, the cross-sectional profiles change continuously, the area utilization coefficient gradually increases, and the volume of the formed working chamber gradually increases, which can maximize the internal volume ratio of the twin-screw vacuum pump and broaden the application scope and field of the twin-screw vacuum pump.

[0043] ② On the suction side, the inter-stage pressure difference is small, and the tooth width of the two screw rotors is small. On the exhaust side, the inter-stage pressure difference is large, and the tooth width of the two screw rotors is large, which has good inter-stage sealing performance and improves the ultimate vacuum degree of the twin-screw vacuum pump; the two screw rotors form a larger working chamber volume on the suction side, have a larger air intake, and increase the pumping speed of the twin-screw vacuum pump.

[0044] ③ The pitch of the two screw rotors changes in sections with continuous transition, and the pitch change mode is determined by the length of the sectioned rotors, which is beneficial to the design and processing of the screw rotors. The center distance between the two screw rotors remains unchanged, and the center lines are arranged in parallel, which is convenient for installation and positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention is further described below in conjunction with the accompanying drawings.

[0046] Figure 1 The left-handed cross-sectional profile (1001) of the left-handed screw rotor (100) is a graph.

[0047] Figure 2 The right-handed cross-sectional profile (2001) of the right-handed screw rotor (200) is a curve diagram.

[0048] Figure 3 It is a diagram showing the meshing relationship between the left-handed cross-section profile (1001) and the right-handed cross-section profile (2001).

[0049] Figure 4 The diagram is a meshing diagram of a left-handed screw rotor (100) and a right-handed screw rotor (200) during operation.

[0050] Figure 5 The invention is a cross-sectional view of the meshing of a left-handed screw rotor (100) and a right-handed screw rotor (200) during operation.

[0051] Figure 6 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the first axial position Ⅰ-Ⅰ.

[0052] Figure 7 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the second axial position II-II.

[0053] Figure 8It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the third axial position III-III.

[0054] Fig. 9 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the fourth axial position IV-IV.

[0055] Fig.10 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the fifth axial position V-V.

[0056] Fig.11 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the sixth axial position VI-VI.

[0057] Fig.12 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the seventh axial position Ⅶ-Ⅶ.

[0058] Fig.13 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the eighth axial position VIII-VIII.

[0059] Fig.14 It is a meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the ninth axial position IX-IX.

[0060] In the figure: τ—helical angle; R 1 (τ)—radius of left-handed tooth top arc AB; R 2 —The pitch radius of the left-handed cross-section profile (1001); R 3 (τ)—radius of the left-hand tooth root arc DE; R 4 (τ)—radius of the base circle of the left-handed circular involute BC; r 1 (τ)—radius of the right-handed tooth top arc ab; r 2 —The pitch radius of the right-handed section profile (2001); r 3 (τ)—radius of the right-handed tooth root arc de; r 4 (τ)—radius of the base circle of the right-handed circular involute bc; m—center distance between the left-handed screw rotor (100) and the right-handed screw rotor (200); L 1 - rotor length of the left-handed equal pitch section (101); L 2 — rotor length of the left-handed conical section (102); L 3 - rotor length of the left-hand variable pitch section (103); point O 1 , O 2—are the rotation center points of the cross-sectional profiles of the left-handed screw rotor (100) and the right-handed screw rotor (200), respectively, and the axes on which they are located are the rotation center lines of the two screw rotors. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0062] like Figure 1 The figure shows a curve diagram of the left-handed cross-sectional profile (1001) of the left-handed screw rotor (100). The left-handed cross-sectional profile (1001) of the left-handed screw rotor (100) is composed of a left-handed tooth top arc AB, a left-handed circular involute BC, a left-handed first cycloid CD, a left-handed tooth root arc DE and a left-handed second cycloid EA.

[0063] like Figure 2 The figure shows a right-handed cross-sectional profile (2001) of a right-handed screw rotor (200). The right-handed cross-sectional profile (2001) of the right-handed screw rotor (200) is composed of a right-handed tooth top arc ab, a right-handed circular involute bc, a right-handed first cycloid cd, a right-handed tooth root arc de and a right-handed second cycloid ea.

[0064] At the same axial position, the radius r of the right-handed tooth top arc ab is 1 (τ) and the radius R of the left-handed tooth tip arc AB 1 (τ) is equal, the pitch radius r of the right-handed cross-section profile (2001) 2 and the pitch radius R of the left-handed section profile (1001) 2 Equal and satisfy: r 2 +R 2 =m, the radius r of the right-hand tooth root arc de 3 (τ) and the radius R of the left-hand tooth root arc DE 3 (τ) is equal, the base circle radius r of the right-handed circular involute bc 4 (τ) and the base circle radius R of the left-handed circular involute BC 4 (τ) are equal.

[0065] like Figure 3 The figure shows the meshing relationship diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001). At the same axial position, the right-handed tooth tip arc ab, the right-handed circular involute bc, the right-handed first cycloid cd, the right-handed tooth root arc de and the right-handed second cycloid ea of ​​the right-handed cross-sectional profile (2001) can be correctly meshed with the left-handed tooth root arc DE, the left-handed circular involute BC, the upper end point B of the left-handed tooth tip arc AB, the left-handed tooth tip arc AB and the lower end point A of the left-handed tooth tip arc AB of the left-handed cross-sectional profile (1001) in sequence.

[0066] like Figure 4As shown in FIG. 1 , it is a diagram of the meshing of the left-handed screw rotor (100) and the right-handed screw rotor (200) during operation; Figure 5 The figure shows a meshing cross-sectional view of a left-handed screw rotor (100) and a right-handed screw rotor (200) during operation. From the first axial position Ⅰ-Ⅰ to the ninth axial position IX-IX, the spiral expansion angle τ changes continuously from 0 to 8π; at the first axial position Ⅰ-Ⅰ, the spiral expansion angle τ=0; at the fifth axial position Ⅴ-Ⅴ, the spiral expansion angle τ=4π; at the seventh axial position Ⅶ-Ⅶ, the spiral expansion angle τ=6π; at the ninth axial position IX-IX, the spiral expansion angle τ=8π. The first axial position Ⅰ-Ⅰ is the exhaust side of the screw rotor, and the ninth axial position IX-IX is the suction side of the screw rotor.

[0067] From the first axial position Ⅰ-Ⅰ to the ninth axial position IX-IX, the left-handed screw rotor (100) is arranged in sections: from the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ is a left-handed equal pitch section (101), from the fifth axial position Ⅴ-Ⅴ to the seventh axial position Ⅶ-Ⅶ is a left-handed conical section (102), from the seventh axial position Ⅶ-Ⅶ to the ninth axial position Ⅸ-Ⅸ is a left A rotationally variable pitch section (103); a right-handed screw rotor (200) is arranged in sections: from the first axial position I-I to the fifth axial position V-V is a right-handed equal pitch section (201), from the fifth axial position V-V to the seventh axial position VII-VII is a right-handed conical section (202), and from the seventh axial position VII-VII to the ninth axial position IX-IX is a right-handed variable pitch section (203).

[0068] From the first axial position Ⅰ-Ⅰ to the ninth axial position IX-IX, the cross-sectional profiles of the left-handed screw rotor (100) change continuously, and the area utilization coefficient gradually increases, but the cross-sectional profiles of each section are composed of five curves connected end to end, and the type is the same; the left-handed equal pitch section (101) has a gradually decreasing tooth top width, and the pitch changes in a constant pitch; the left-handed conical section (102) is linearly conical, the tooth top width gradually decreases, the pitch changes in a variable pitch, and the pitch gradually increases; the left-handed variable pitch section (103) has a gradually decreasing tooth top width, and the pitch changes in a variable pitch, and the pitch gradually increases; the left-handed equal pitch section (101) has a gradually decreasing tooth top width, and the pitch changes in a variable pitch, and the pitch gradually increases; A left-handed conical section (102) is used as a transition between the pitch section (101) and the left-handed variable pitch section (103); at the fifth axial position V-V, the left-handed equal pitch section (101) and the left-handed conical section (102) have the same cross-sectional profile; at the seventh axial position VII-VII, the left-handed conical section (102) and the left-handed variable pitch section (103) have the same cross-sectional profile; from the first axial position I-I to the ninth axial position IX-IX, the center distance between the right-handed screw rotor (200) and the left-handed screw rotor (100) remains unchanged, so that correct meshing can be achieved, and the volume of the formed working chamber gradually increases.

[0069] At the same axial position, the pitch P(τ) of the left-handed screw rotor (100) and the pitch p(τ) of the right-handed screw rotor (200) are equal, and the spiral directions are opposite. From the first axial position Ⅰ-Ⅰ to the ninth axial position IX-IX, the spiral expansion angle τ changes continuously from 0 to 8π; at the first axial position Ⅰ-Ⅰ, the spiral expansion angle τ=0; at the fifth axial position Ⅴ-Ⅴ, the spiral expansion angle τ=4π; at the seventh axial position Ⅶ-Ⅶ, the spiral expansion angle τ=6π; at the ninth axial position IX-IX, the spiral expansion angle τ=8π; as the spiral expansion angle τ changes from 0 to 8π, the pitch P(τ) of the left-handed screw rotor (100) changes as follows: from the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the pitch P(τ) of the left-handed equal pitch section (101) remains unchanged and satisfies:

[0070]

[0071] Where, L 1 is the rotor length of the left-handed equal pitch section (101);

[0072] From the seventh axial position VII-VII to the ninth axial position IX-IX, the pitch P (τ) of the left-handed variable pitch section (103) gradually increases and satisfies:

[0073]

[0074] Wherein, α is the variable pitch coefficient of the left-hand variable pitch section (103); L 3 is the rotor length of the left-hand variable pitch section (103);

[0075] From the fifth axial position V-V to the seventh axial position VII-VII, the pitch P (τ) of the left-handed conical section (102) gradually increases and satisfies:

[0076]

[0077] Where, L 2 is the rotor length of the left-handed conical section (102);

[0078] As the spiral expansion angle τ changes from 0 to 8π, the axial length Z(τ) of the left-handed screw rotor (100) changes as follows:

[0079]

[0080] At the fifth axial position V-V, the pitch of the left-handed equal pitch section (101) is equal to the pitch of the left-handed conical section (102), and at the seventh axial position VII-VII, the pitch of the left-handed conical section (102) is equal to the pitch of the left-handed variable pitch section (103).

[0081] like Figure 6 , Figure 7, Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 and Fig.14 As shown, they are respectively the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the first axial position Ⅰ-Ⅰ, the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the second axial position Ⅱ-Ⅱ, the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the third axial position Ⅲ-Ⅲ, the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the fourth axial position Ⅳ-Ⅳ, and the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the fifth axial position Ⅴ-Ⅴ. (1001) and the right-handed cross-sectional profile (2001) meshing diagram, the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the sixth axial position Ⅵ-Ⅵ, the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the seventh axial position Ⅶ-Ⅶ, the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the eighth axial position Ⅷ-Ⅷ, and the meshing diagram of the left-handed cross-sectional profile (1001) and the right-handed cross-sectional profile (2001) at the ninth axial position Ⅸ-Ⅸ. As the helical expansion angle τ increases from 0 to 8π, the radius R of the left-handed tooth top arc AB of the left-handed cross-sectional profile (1001) increases. 1 The variation law of (τ) is as follows: from the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the radius R of the left-handed tooth top arc AB is 1 (τ) remains unchanged and satisfies:

[0082] R 1 (τ) = R 1a , 0≤τ≤4π

[0083] In the formula, R 1a is the initial radius of the left-handed tooth tip arc AB at the first axial position Ⅰ-Ⅰ;

[0084] From the seventh axial position VII-VII to the ninth axial position IX-IX, the radius R of the left-handed tooth top arc AB 1 (τ) remains unchanged and satisfies:

[0085] R 1 (τ) = R 1c , 6π≤τ≤8π

[0086] In the formula, R 1c is the initial radius of the left-handed tooth tip arc AB at the seventh axial position VII-VII;

[0087] From the fifth axial position V-V to the seventh axial position VII-VII, the radius R of the left-handed tooth top arc AB1 (τ) increases linearly with the axial length z(τ) and satisfies:

[0088]

[0089] As the helix expansion angle τ increases from 0 to 8π, the radius R of the left-hand tooth root arc DE 3 The changing rule of (τ) is:

[0090] R 3 (τ) = mR 1 (τ), 0≤τ≤8π

[0091] Wherein, m is the center distance between the left-handed screw rotor (100) and the right-handed screw rotor (200);

[0092] As the helix expansion angle τ increases from 0 to 8π, the base circle radius R of the left-handed circular involute BC 4 The changing rule of (τ) is:

[0093] From the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the base circle radius R of the left-handed circular involute BC 4 (τ) gradually increases,

[0094] R 4 The absolute value of the first-order derivative of (τ) gradually increases and satisfies:

[0095]

[0096] In the formula, R 4a is the initial base circle radius of the left-handed circular involute BC at the first axial position Ⅰ-Ⅰ; R 4b k is the initial base circle radius of the left-handed circular involute BC at the fifth axial position V-V; 1 is the variable base circle coefficient of the left-handed equal pitch segment (101);

[0097] From the seventh axial position VII-VII to the ninth axial position IX-IX, the base circle radius R of the left-handed circular involute BC 4 (τ) gradually increases, R 4 The absolute value of the first-order derivative of (τ) gradually decreases and satisfies:

[0098]

[0099] In the formula, R 4c is the initial base circle radius of the left-handed involute BC at the seventh axial position Ⅶ-Ⅶ; R 4d k is the initial base circle radius of the left-handed involute BC at the ninth axial position IX-IX; 2 is the variable base circle coefficient of the left-hand variable pitch section (103);

[0100] From the fifth axial position V-V to the seventh axial position VII-VII, the base circle radius R of the left-handed circular involute BC 4 (τ) gradually increases, R 4 The absolute value of the first-order derivative of (τ) remains unchanged and satisfies:

[0101]

[0102] 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 segmented variable cross-section screw rotor, comprising: A left-handed screw rotor (100) and a right-handed screw rotor (200); characterized in that: from the first axial position I-I to the ninth axial position IX-IX, the left-handed screw rotor (100) is arranged in sections: from the first axial position I-I to the fifth axial position V-V is a left-handed equal pitch section (101), from the fifth axial position V-V to the seventh axial position VII-VII is a left-handed conical section (102), from the seventh axial position VII-VII to the ninth axial position IX-IX is a left-handed variable pitch section (103); The screw rotor (200) is arranged in sections: from the first axial position I-I to the fifth axial position V-V is a right-handed equal pitch section (201), from the fifth axial position V-V to the seventh axial position VII-VII is a right-handed conical section (202), and from the seventh axial position VII-VII to the ninth axial position IX-IX is a right-handed variable pitch section (203); from the first axial position I-I to the ninth axial position IX-IX, the cross-sectional profiles of the left-handed screw rotor (100) change continuously, and the area utilization coefficient gradually increases, but each The cross-sectional profiles are composed of five segments of curves connected end to end and of the same type; the left-handed equal pitch segment (101) has a gradually decreasing tooth top width, and the pitch changes in a constant pitch manner; the left-handed conical segment (102) is linearly conical, the tooth top width gradually decreases, the pitch changes in a variable pitch manner, and the pitch gradually increases; the left-handed variable pitch segment (103) has a gradually decreasing tooth top width, the pitch changes in a variable pitch manner, and the pitch gradually increases; a left-handed conical segment (103) is used between the left-handed equal pitch segment (101) and the left-handed variable pitch segment (103). The left-handed screw rotor (200) and the left-handed screw rotor (100) transition from one axial position to another axial position. The left-handed equal pitch section (101) and the left-handed conical section (102) have the same cross-sectional profile at the fifth axial position V-V; the left-handed conical section (102) and the left-handed variable pitch section (103) have the same cross-sectional profile at the seventh axial position VII-VII; from the first axial position I-I to the ninth axial position IX-IX, the center distance between the right-handed screw rotor (200) and the left-handed screw rotor (100) remains unchanged, so that correct meshing can be achieved, and the volume of the formed working chamber gradually increases.

2. A segmented variable cross-section screw rotor as claimed in claim 1, characterized in that: From the first axial position Ⅰ-Ⅰ to the ninth axial position IX-IX, the helical expansion angle τ changes continuously from 0 to 8π; at the first axial position Ⅰ-Ⅰ, the helical expansion angle τ=0; at the fifth axial position Ⅴ-Ⅴ, the helical expansion angle τ=4π; at the seventh axial position Ⅶ-Ⅶ, the helical expansion angle τ=6π; at the ninth axial position Ⅸ-Ⅸ, the helical expansion angle τ=8π; as the helical expansion angle τ changes from 0 to 8π, the pitch P(τ) of the left-handed screw rotor (100) changes as follows: from the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the pitch P(τ) of the left-handed equal pitch section (101) remains unchanged and satisfies: Where, L1 is the rotor length of the left-handed equal pitch section (101); From the seventh axial position VII-VII to the ninth axial position IX-IX, the pitch P (τ) of the left-handed variable pitch section (103) gradually increases and satisfies: Wherein, α is the variable pitch coefficient of the left-handed variable pitch section (103); L3 is the rotor length of the left-handed variable pitch section (103); From the fifth axial position V-V to the seventh axial position VII-VII, the pitch P (τ) of the left-handed conical section (102) gradually increases and satisfies: Wherein, L2 is the rotor length of the left-handed conical section (102); As the spiral expansion angle τ changes from 0 to 8π, the axial length Z(τ) of the left-handed screw rotor (100) changes as follows: At the same axial position, the pitch p(τ) of the right-handed screw rotor (200) and the pitch P(τ) of the left-handed screw rotor (100) are equal, and the spiral directions are opposite.

3. The segmented variable cross-section screw rotor according to claim 1, characterized in that: The left-handed cross-sectional profile (1001) of the left-handed screw rotor (100) is composed of a left-handed tooth top arc AB, a left-handed circular involute BC, a left-handed first cycloid CD, a left-handed tooth root arc DE and a left-handed second cycloid EA; as the spiral expansion angle τ changes from 0 to 8π, the radius R1(τ) of the left-handed tooth top arc AB of the left-handed cross-sectional profile (1001) changes as follows: from the first axial position I-I to the fifth axial position V-V, the radius R1(τ) of the left-handed tooth top arc AB remains unchanged and satisfies: R1(τ)=R 1a ,0≤τ<4π In the formula, R 1a is the initial radius of the left-handed tooth tip arc AB at the first axial position Ⅰ-Ⅰ; From the seventh axial position VII-VII to the ninth axial position IX-IX, the radius R1(τ) of the left-handed tooth top arc AB remains unchanged and satisfies: R1(τ)=R 1c ,6π≤τ≤8π In the formula, R 1c is the initial radius of the left-handed tooth tip arc AB at the seventh axial position VII-VII; From the fifth axial position V-V to the seventh axial position VII-VII, the radius R1(τ) of the left-handed tooth tip arc AB increases linearly with the axial length Z(τ), and satisfies: As the helix expansion angle τ changes from 0 to 8π, the radius R3(τ) of the left-hand tooth root arc DE changes as follows: R3(τ)=m-R1(τ),0≤τ≤8π Wherein, m is the center distance between the left-handed screw rotor (100) and the right-handed screw rotor (200); As the helix expansion angle τ changes from 0 to 8π, the change rule of the base circle radius R4(τ) of the left-handed circular involute BC is: From the first axial position Ⅰ-Ⅰ to the fifth axial position Ⅴ-Ⅴ, the base circle radius R4(τ) of the left-handed circular involute BC gradually increases, and the absolute value of the first-order derivative of R4(τ) gradually increases, and satisfies: In the formula, R 4a is the initial base circle radius of the left-handed circular involute BC at the first axial position Ⅰ-Ⅰ; R 4b is the initial base circle radius of the left-handed circular involute BC at the fifth axial position V-V; k1 is the variable base circle coefficient of the left-handed equal pitch segment (101); From the seventh axial position VII-VII to the ninth axial position IX-IX, the base circle radius R4(τ) of the left-handed circular involute BC gradually increases, and the absolute value of the first-order derivative of R4(τ) gradually decreases, and satisfies: In the formula, R 4c is the initial base circle radius of the left-handed involute BC at the seventh axial position Ⅶ-Ⅶ; R 4d is the initial base circle radius of the left-handed circular involute BC at the ninth axial position IX-IX; k2 is the variable base circle coefficient of the left-handed variable pitch section (103); From the fifth axial position V-V to the seventh axial position VII-VII, the base circle radius R4(τ) of the left-handed circular involute BC gradually increases, the absolute value of the first-order derivative of R4(τ) remains unchanged, and satisfies:

4. The segmented variable cross-section screw rotor according to claim 1, characterized in that: The right-handed cross-sectional profile (2001) of the right-handed screw rotor (200) is composed of a right-handed tooth top arc ab, a right-handed circular involute bc, a right-handed first cycloid cd, a right-handed tooth root arc de and a right-handed second cycloid ea; at the same axial position, the radius r1 (τ) of the right-handed tooth top arc ab and the radius R1 (τ) of the left-handed tooth top arc AB are equal, the pitch circle radius r2 of the right-handed cross-sectional profile (2001) and the pitch circle radius R2 of the left-handed cross-sectional profile (1001) are equal, and satisfy: r2+R2=m, the radius r3 (τ) of the right-handed tooth root arc de and the radius R3 (τ) of the left-handed tooth root arc DE are equal, and the base circle radius r4 (τ) of the right-handed circular involute bc and the base circle radius R4 (τ) of the left-handed circular involute BC are equal.

5. The segmented variable cross-section screw rotor according to claim 1, characterized in that: At the same axial position, the right-handed tooth top arc ab, the right-handed circular involute bc, the right-handed first cycloid cd, the right-handed tooth root arc de and the right-handed second cycloid ea of ​​the right-handed cross-sectional profile (2001) can respectively achieve correct meshing with the left-handed tooth root arc DE, the left-handed circular involute BC, the upper end point B of the left-handed tooth top arc AB, the left-handed tooth top arc AB and the lower end point A of the left-handed tooth top arc AB of the left-handed cross-sectional profile (1001).

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