A two-stage compression vane vacuum pump with asymmetric cylinder profile

Abstract

The present invention discloses a two-stage compression vane vacuum pump with an asymmetric cylinder profile. The vacuum pump comprises a front cover (1), a rotor (2), a cylinder (3), a vane (4) and a rear cover (5). The contour profile of the cylinder (3) consists of five different curves, and the first-order derivative and the second-order derivative are continuous. During operation, two cavities with different volumes and asymmetry are formed between the front cover (1), the cylinder (3), the rear cover (5) and the rotor (2). The gas completes a primary compression process in the primary cavity (301) and then enters the secondary cavity (302) for secondary compression, thereby realizing two-stage compression. The front cover (1) is provided with a first air intake port (101) and a second air exhaust port (102), and the rear cover (5) is provided with a first air exhaust port (502) and a second air intake port (501). The disclosed vacuum pump not only has a larger internal volume ratio and improves the vacuum degree, but also reduces its power consumption and the clearance volume.

Description

Technical Field

[0001] The invention relates to a vacuum pump, in particular to a two-stage compression vane vacuum pump with asymmetric cylinder profile. Background Art

[0002] The vane vacuum pump is a positive displacement vacuum pump. It is mainly composed of end cover, pump body, rotor, and vane. The rotor is installed in the pump cavity, and the vane is installed in the groove of the rotor. When the rotor rotates, the vane is thrown out of the groove under the action of centrifugal force and closely adheres to the inner wall of the cylinder to rotate with the rotor. A closed working chamber with periodic changes is formed between the suction and exhaust end covers, vanes, rotors and cylinders to complete the gas suction, compression and discharge process. It has the advantages of high efficiency, small size, ability to inhale impurity-containing gases and simple structure. It is widely used in metallurgy, electronics, medicine, and automobile industries; its key technology is the contour line of the cylinder, which directly affects the working performance of the vacuum pump.

[0003] With the expansion of the application field of vacuum pumps, the requirements for their vacuum degree are gradually increasing, so the vacuum pumps are required to have a larger internal volume ratio; a double-cavity vane compressor cylinder body is proposed in the patent with publication number CN 209671208 U, which adopts a cavity profile with a secondary helix line structure to realize an asymmetric double-cavity structure, increase the flow rate of the transported liquid, and improve the force condition of the vane; however, the single-stage compression multi-cavity parallel form does not significantly improve the internal volume ratio of the vacuum pump. Summary of the invention

[0004] In order to increase the internal volume ratio of the vane vacuum pump to a large extent, thereby increasing the ultimate vacuum degree of the vane vacuum pump, and at the same time to enrich the types of the cylinder end profile of the vane vacuum pump, the present invention proposes a two-stage compression vane vacuum pump with an asymmetric cylinder profile. The contour profile of the cylinder adopts a sinusoidal spiral, an eccentric arc and a high-order curve to construct a new cylinder profile. By adjusting the proportion of the central angle corresponding to the suction section curve and the discharge section curve, the geometric structure of the working chamber is asymmetric, thereby reducing the exhaust volume and improving the internal volume ratio. At the same time, a two-stage structural design is adopted, so that the compressed gas enters the secondary working chamber after the first-stage compression is completed, thereby further improving the pressure ratio. The relevant parameters can be adjusted according to the design working conditions to meet the performance requirements of the vane vacuum pump. The new cylinder profile consists of a suction section curve and a discharge section curve, and any position on the entire cylinder profile is continuous and smooth, meeting the characteristic requirements of the cylinder profile that the first-order derivative is continuous and smooth and the second-order derivative is continuous. There is no rigid impact or soft impact on the sliding vane in the direction of the sliding groove, which is beneficial to improving its own stress condition, suppressing the vibration of the sliding vane and the impact on the inner wall of the cylinder, so as to ensure the smooth and reliable operation of the sliding vane.

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

[0006] A two-stage compression vane vacuum pump with an asymmetric cylinder profile comprises: a front cover (1), a rotor (2), a cylinder (3), a vane (4) and a rear cover (5); the profile of the cylinder (3) is formed by smoothly connecting five curves, which are: a first-stage suction section curve AB, a first-stage discharge section curve BC, a first transition curve CD, a second-stage composite function curve DEF, and a second transition curve FA; the profile of the cylinder (3) is continuous in first-order derivative and second-order derivative at any point, and has a continuous curvature radius that is positive;

[0007] During operation, the rotor (2) is assembled in the cylinder (3), and the front cover (1) and the rear cover (5) are assembled on both axial sides of the cylinder (3); two cavities with different volumes are formed between the front cover (1), the cylinder (3), the rear cover (5) and the rotor (2): the first-stage cavity (301) with a larger volume has an asymmetric axial projection, and the axial projection of the first-stage cavity (301) is composed of a first-stage suction section curve AB and a first-stage discharge section curve BC, and the center angle θ2 corresponding to the first-stage suction section curve AB is smaller than the center angle θ1 corresponding to the first-stage discharge section curve BC; the second-stage cavity (302) with a smaller volume has an axial projection composed of a first transition curve CD, a second-stage composite function curve DEF and a second transition curve FA, and the axial projection is axially symmetric;

[0008] The primary cavity (301) and the secondary cavity (302) are divided into n working cavities with different volumes by n sliding plates (4); and the minimum closed working cavity volume S in the primary cavity (301) is 1min Greater than the maximum closed working chamber volume S in the secondary chamber (302) 2max .

[0009] A two-stage compression vane vacuum pump with an asymmetric cylinder profile, wherein the equations of the five component curves of the cylinder (3) profile are as follows:

[0010] A polar coordinate system is established with the rotation center of the rotor (2) as the coordinate origin O;

[0011] The equation of the first-stage suction curve AB is:

[0012] The equation of the first-stage discharge curve BC is:

[0013] Equation of the first transition curve CD:

[0014] c0, c1, c2, c3, c4, c5 are constants, determined by the following 6 equations:

[0015]

[0016] The equation of the second-order composite function curve DEF is:

[0017] The second transition curve FA is obtained by symmetry of the first transition curve CD about the x-axis, and its equation is:

[0018]

[0019] Wherein, ρ is the radius vector of the profile line of the cylinder (3), mm;

[0020] R1—is the maximum value of the contour line radius of the cylinder (3), mm; controls the volume of the primary cavity (301);

[0021] e—is the eccentricity, in mm; it controls the volume of the secondary cavity (302);

[0022] R2—the minimum value of the contour line radius of the cylinder (3), mm;

[0023] α—is the central angle of the first transition curve CD, rad;

[0024] rad;

[0025] θ1—is the central angle of the first-stage suction section curve AB, rad;

[0026] θ2—is the central angle of the first-stage discharge curve BC, rad;

[0027] θ1+θ2=π, rad;

[0028] t—polar angle, rad.

[0029] A two-stage compression vane vacuum pump with an asymmetric cylinder profile, wherein the cylinder (3) has six special points A, B, C, D, E and F on its profile: a first point A, a second point B, a third point C, a fourth point D, a fifth point E and a sixth point F;

[0030] The first point A and the third point C are the minimum values ​​of the radial vector from the origin O on the contour line of the cylinder (3), wherein the first point A is located at The radius vector ρ AB On, and The third point C is located at The radius vector ρ BC On, and On the bottom circle with the origin O as the center and the radius R3;

[0031] The second point B is the maximum value of the radial vector from the origin O on the contour line of the cylinder (3), located at The radius vector ρ AB On, and Controlling the axial projection area of ​​the first-stage cavity (301);

[0032] The fourth point D is a point on the contour line of the cylinder (3) that smoothly connects the secondary composite function curve DEF and the first transition curve CD, wherein the fourth point D is located at The radius vector ρ CD The sixth point F is a point on the contour line of the cylinder (3) that smoothly connects the secondary composite function curve DEF and the second transition curve FA, and the sixth point F is located at The radius vector ρ FA superior;

[0033] The fifth point E is the second extreme value of the vector radius from the origin O on the contour line of the cylinder (3), and is located at the vector radius ρ at t = π. DEF On, and DEF (π)=R2+e, controlling the axial projection area of ​​the secondary cavity (302);

[0034] The contour line of the cylinder (3) has smooth transitions at five special points A, B, C, D and F, and has continuous first-order derivatives, continuous second-order derivatives, and continuous curvature radii that are all positive.

[0035] A two-stage compression vane vacuum pump with an asymmetric cylinder profile, wherein the front cover (1) is provided with: a first-stage air intake port (101) and a second-stage air exhaust port (102); and the rear cover (5) is provided with: a first-stage air exhaust port (502) and a second-stage air intake port (501);

[0036] The rotor (2) is symmetrically provided with n centripetal uniform sliding grooves, wherein 6≤n≤12, and the sliding vanes (4) are correspondingly installed in the sliding grooves;

[0037] During operation, the pumped gas enters the primary cavity (301) through the primary air intake port (101) on the front end cover (1) to realize the air intake process. After being compressed in the primary cavity (301), the pumped gas is discharged from the primary air exhaust port (502) on the rear end cover (5). Then, the pumped gas enters the secondary cavity (302) through the secondary air intake port (501) on the rear end cover (5). After being compressed, the pumped gas is discharged from the secondary air exhaust port (102) on the air intake end cover (1), thereby realizing a two-stage compression process.

[0038] During operation, the rotor (2) is assembled in the cylinder (3), the front end cover (1) and the rear end cover (5) are assembled on both axial sides of the cylinder (3), and n sliding vanes (4) are installed in n sliding grooves of the rotor (2);

[0039] The first-stage air inlet (101) on the front end cover (1) intersects with the axial projection of the first-stage suction section curve AB on the front end cover (1), and during operation, when the maximum closed working chamber S formed in the first-stage cavity (301) 1max When one of the sliding plates is tangent to the edge profile of the first-stage air intake port (101);

[0040] The first-stage exhaust port (502) is located at the position where the first-stage exhaust section curve BC is axially projected on the rear end cover (5), and is formed in the smallest closed working chamber S in the first-stage chamber (301). 1min When one of the sliding vanes is tangent to the edge profile of the first-stage exhaust port (502);

[0041] The secondary air intake port (501) is located at the position where the axial projection of the secondary suction section curve CDE is projected on the rear end cover (5), and is formed in the maximum closed working chamber S in the secondary cavity (302). 2max When one of the sliding plates is tangent to the edge profile of the secondary air intake port (501);

[0042] The secondary exhaust port (102) on the front end cover (1) is located at the position where the secondary exhaust section curve EFA is axially projected on the front end cover (1), and is formed in the minimum closed working chamber S in the secondary chamber (302). 2min When one of the sliding vanes is tangent to the edge profile of the secondary exhaust port (102).

[0043] The beneficial effects of the present invention are:

[0044] ① The proposed two-stage compression vane vacuum pump with asymmetric cylinder profile can achieve two-stage compression, and the first-stage cavity (301) is asymmetric, thereby increasing the internal volume ratio, and further increasing the compression ratio and the ultimate vacuum degree of the vacuum pump.

[0045] ② The proposed two-stage compression vane vacuum pump with an asymmetric cylinder profile can reduce the clearance volume and thus improve the volumetric efficiency.

[0046] ③ The proposed two-stage compression vane vacuum pump with an asymmetric cylinder profile has continuous first-order derivatives, continuous second-order derivatives, and positive curvatures, which is beneficial to improving the force condition of the vane and reducing the wear of the vane.

[0047] ④ The proposed two-stage compression vane vacuum pump profile with an asymmetric cylinder profile enriches the types of vane pump profiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The diagram shows the components of a two-stage compression vane vacuum pump with an asymmetric cylinder profile.

[0049] Figure 2 It is an axial view of a two-stage compression vane vacuum pump with an asymmetric cylinder profile.

[0050] Figure 3 The invention discloses an outline line diagram of a cylinder (3) of a two-stage compression vane type vacuum pump having an asymmetric cylinder line.

[0051] Figure 4 The diagram shows a primary cavity (301) and a secondary cavity (302) formed between a rotor (2) and a cylinder (3).

[0052] Figure 5 It is the maximum inspiratory volume diagram during the first stage of inspiration.

[0053] Figure 6 It is the exhaust volume diagram during the first stage exhaust process.

[0054] Figure 7 It is the maximum inspiratory volume diagram during the secondary inspiration process.

[0055] Figure 8 It is the exhaust volume diagram during the two-stage exhaust process.

[0056] Fig. 9 It is a diagram showing the opening positions of the suction and exhaust ports of the rear end cover (5).

[0057] Fig.10 The figure is a diagram showing the opening positions of the intake and exhaust ports of the front cover (1).

[0058] In the figure: 1—right end cover (1); 2—rotor (2); 3—cylinder (3); 4—vane (4); 5—left end cover (5); 301—primary cavity (301); 302—secondary cavity (302); 101—primary air intake port (101); 102—secondary air exhaust port (102); 502—primary air exhaust port (502); 501—secondary air intake port (501); R1—maximum value of the contour line radius of the cylinder (3); R2—minimum value of the contour line radius of the cylinder (3). DETAILED DESCRIPTION

[0059] The present invention will be further described below in conjunction with the accompanying drawings.

[0060] like Figure 1 The figure shows a component diagram of a two-stage compression vane vacuum pump with an asymmetric cylinder profile, comprising: a front cover (1), a rotor (2), a cylinder (3), a vane (4) and a rear cover (5). The rotor (2) is symmetrically provided with m centripetal or eccentric sliding grooves, 6≤m≤12, and a vane (4) is installed in each sliding groove.

[0061] like Figure 2The figure shows an axial view of a two-stage compression vane vacuum pump with an asymmetric cylinder profile, wherein the dotted lines respectively represent the first-stage air intake port (101), the second-stage air exhaust port (102), and the first-stage air exhaust port (502); and the axial projection of the second-stage air intake port (501) on the cylinder (3).

[0062] like Figure 3 As shown, it is a contour line diagram of a cylinder (3) of a two-stage compression vane vacuum pump with an asymmetric cylinder line. The contour line diagram of the cylinder (3) is formed as follows: a polar coordinate system is established with the rotation center O of the rotor (2) as the origin, and circles with radii R1 and R2 are drawn with O as the center. The curvature radius of the first-stage suction section arc AB increases from R2 to R1, and the angle range is The curvature radius of the arc BC of the first-stage discharge section falls back to R1 based on R2, and the angle range is The secondary composite function curve DEF is an eccentric arc with an eccentricity of e, and the angle range is The secondary composite function curve DEF is connected to the primary suction arc AB and the primary discharge arc BC by a higher-order curve: the first transition curve CD and the second transition curve FA, the angle ranges are and The equation is established as follows:

[0063] The first-stage suction section curve AB is a sinusoidal spiral, and the equation is:

[0064]

[0065] The first-stage discharge curve BC is a sinusoidal spiral, and the equation is:

[0066]

[0067] The first transition curve CD is a high-order curve, and its equation is:

[0068]

[0069] c0, c1, c2, c3, c4, c5—constants determined by the following system of equations:

[0070]

[0071] The secondary composite function curve DEF is an eccentric arc, and its equation is:

[0072]

[0073] The second transition curve FA is obtained by symmetry of the first transition curve CD about the x-axis, and its equation is:

[0074]

[0075] Where: ρ is the radius vector of the profile line of the cylinder (3), mm;

[0076] R1—is the maximum value of the contour line radius of the cylinder (3), mm; controls the volume of the primary cavity (301);

[0077] e—eccentricity, mm; controls the volume of the secondary cavity (302);

[0078] R2—the minimum value of the contour line radius of the cylinder (3), mm;

[0079] α—center angle of the first transition curve CD, rad;

[0080] rad;

[0081] θ1—center angle of the first-stage suction section curve AB, rad;

[0082] θ2—center angle of the first-stage discharge curve BC, rad;

[0083] θ1+θ2=π, rad;

[0084] t—polar angle, rad.

[0085] like Figure 4 As shown, a primary cavity (301) and a secondary cavity (302) formed between the rotor (2) and the cylinder (3) are shown, wherein the primary cavity (301) is responsible for the primary compression process of the vacuum pump, and the secondary cavity (302) is responsible for the secondary compression process of the vacuum pump.

[0086] like Figure 5 As shown, it is a maximum suction volume diagram of the first-stage suction process of a two-stage compression vane vacuum pump. During the counterclockwise rotation of the rotor, when the maximum closed working chamber S formed in the first-stage cavity (301) 1max When the sliding plates are moved, one of the sliding plates is tangent to the edge profile of the primary air inlet (101).

[0087] like Figure 6 As shown, it is a diagram of the exhaust volume of the first-stage exhaust process of a two-stage compression vane vacuum pump. During the counterclockwise rotation of the rotor, when the minimum closed working chamber S formed in the first-stage chamber (301) 1min When the first stage exhaust port (502) is opened, one of the sliding plates is tangent to the edge contour of the first stage exhaust port (502); the pumped gas is discharged through the first stage exhaust port (502) and enters the second stage suction port (501), and the minimum closed working chamber S in the first stage chamber (301) is 1min is always greater than the maximum closed working chamber S in the secondary chamber (302) 2max .

[0088] like Figure 7 As shown, it is a diagram of the maximum suction volume of the second-stage suction process of a two-stage compression vane vacuum pump. During the counterclockwise rotation of the rotor, when the maximum closed working chamber S formed in the second-stage cavity (302) 2max When the sliding plates are moved, one of the sliding plates is tangent to the edge profile of the secondary air inlet (501).

[0089] like Figure 8 As shown, it is a two-stage compression vane vacuum pump two-stage exhaust process exhaust volume diagram, when the rotor rotates counterclockwise, when the minimum closed working chamber S formed in the two-stage chamber (302) 2min When the pumped gas is discharged through the secondary exhaust port (102), one of the sliding vanes is tangent to the edge profile of the secondary exhaust port (102), and the pumped gas is discharged through the secondary exhaust port (102).

[0090] like Fig. 9 As shown, a rear end cover (5) of a two-stage compression vane vacuum pump is provided on the rear end cover (5), wherein: a primary exhaust port (502) and a secondary air intake port (501) are provided, and because the primary exhaust port (502) and the secondary air intake port (501) are on the same side, they are directly connected by a pipe.

[0091] like Fig. 9 As shown, a front end cover (1) of a two-stage compression vane type vacuum pump is provided, wherein the front end cover (1) is provided with: a first air intake port (101) and a second air exhaust port (102).

[0092] 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 two-stage compression vane vacuum pump with an asymmetric cylinder profile, comprising: The front end cover (1), the rotor (2), the cylinder (3), the vane (4) and the rear end cover (5) are characterized in that: the contour line of the cylinder (3) is formed by smoothly connecting five curves, which are: a first-stage suction section curve AB, a first-stage discharge section curve BC, a first transition curve CD, a second-stage composite function curve DEF, and a second transition curve FA. The contour line of the cylinder (3) has continuous first-order derivatives and continuous second-order derivatives at any point, and the radius of curvature is continuous and all positive. During operation, the rotor (2) is assembled in the cylinder (3), and the front cover (1) and the rear cover (5) are assembled on both axial sides of the cylinder (3); two cavities with different volumes are formed between the front cover (1), the cylinder (3), the rear cover (5) and the rotor (2): the first-stage cavity (301) with a larger volume has an asymmetric axial projection, and the axial projection of the first-stage cavity (301) is composed of a first-stage suction section curve AB and a first-stage discharge section curve BC, and the center angle θ2 corresponding to the first-stage suction section curve AB is smaller than the center angle θ1 corresponding to the first-stage discharge section curve BC; the second-stage cavity (302) with a smaller volume has an axial projection composed of a first transition curve CD, a second-stage composite function curve DEF and a second transition curve FA, and the axial projection is axially symmetric; The primary cavity (301) and the secondary cavity (302) are divided into n working cavities with different volumes by n sliding plates (4); and the minimum closed working cavity volume S in the primary cavity (301) is 1min Greater than the maximum closed working chamber volume S in the secondary chamber (302) 2max ; The equations of the five component curves of the contour line of the cylinder (3) are as follows: A polar coordinate system is established with the rotation center of the rotor (2) as the coordinate origin O; The equation of the first-stage suction curve AB is: The equation of the first-stage discharge curve BC is: Equation of the first transition curve CD: c0, c1, c2, c3, c4, c5 are constants, determined by the following 6 equations: The equation of the second-order composite function curve DEF is: The second transition curve FA is obtained by symmetry of the first transition curve CD about the x-axis, and its equation is: Wherein, ρ is the radius vector of the profile line of the cylinder (3), mm; R1—the maximum value of the contour line radius of the cylinder (3), mm; e—eccentricity, mm; R2—the minimum value of the contour line radius of the cylinder (3), mm; α—is the central angle of the first transition curve CD, rad; θ1—is the central angle of the first-stage suction section curve AB, rad; θ2—is the central angle of the first-stage discharge curve BC, rad; θ1+θ2=π, rad; t—polar angle, rad; There are six special points A, B, C, D, E and F on the contour line of the cylinder (3): the first point A, the second point B, the third point C, the fourth point D, the fifth point E and the sixth point F; The first point A and the third point C are the minimum values ​​of the radial vector from the origin O on the contour line of the cylinder (3), wherein the first point A is located at The radius vector ρ AB On, and The third point C is located at The radius vector ρ BC On, and On the bottom circle with the origin O as the center and the radius R3; The second point B is the maximum value of the radial vector from the origin O on the contour line of the cylinder (3), located at The radius vector ρ AB On, and Controlling the axial projection area of ​​the first-stage cavity (301); The fourth point D is a point on the contour line of the cylinder (3) that smoothly connects the secondary composite function curve DEF and the first transition curve CD, wherein the fourth point D is located at The radius vector ρ CD The sixth point F is a point on the contour line of the cylinder (3) that smoothly connects the secondary composite function curve DEF and the second transition curve FA, and the sixth point F is located at The radius vector ρ FA superior; The fifth point E is the second extreme value of the vector radius from the origin O on the contour line of the cylinder (3), and is located at the vector radius ρ at t = π. DEF On, and DEF (π)=R2+e, controlling the axial projection area of ​​the secondary cavity (302); The contour line of the cylinder (3) has smooth transitions at five special points A, B, C, D and F, and has continuous first-order derivatives, continuous second-order derivatives, and continuous curvature radii that are all positive.

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