A vacuum pump

Abstract

Embodiments of the present application provide a kind of vacuum pump, it is related to gas compression field.The vacuum pump includes containing shell, first rotor and second rotor;Wherein, compression cavity is formed in containing shell, first rotor and second rotor are all set in compression cavity, first rotor and second rotor cooperate, first rotor and second rotor are respectively provided with first modified section and second modified section, to make first modified section and second rotor cooperate and second modified section and first rotor cooperate to form flow passage gap.First rotor and second rotor are compressed by engaging for the gas molecules in compression cavity, and a small part of gas molecules can pass through flow passage gap in the compression process, reduce the gathering density of gas molecules in the compression process, relieve the heat of gas molecules, prevent the temperature of gas molecules from being too high in the compression process, to improve the use effect of overall vacuum pump.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vacuum equipment, in particular to a vacuum pump. BACKGROUND

[0002] The claw rotor dry mechanical vacuum pump, also referred to as claw pump, has two conjugate meshing claw rotors. The two claw rotors can compress gas molecules in the working process, but the volume between the rotors decreases during compression, the density of gas molecules increases, and the temperature of gas molecules is further increased, so that the temperature of the exhaust gas is too high at the end of the exhaust, thereby affecting the use effect of the overall vacuum pump. SUMMARY

[0003] The present application provides a vacuum pump which can prevent the temperature of gas molecules from being too high during compression, thereby improving the use effect of the overall vacuum pump.

[0004] Embodiments of the present application can be implemented as follows:

[0005] Embodiments of the present application provide a vacuum pump, which comprises:

[0006] The housing, the first rotor and the second rotor;

[0007] Wherein, the compression cavity is formed in the housing, the first rotor and the second rotor are arranged in the compression cavity, the first rotor and the second rotor are engaged and matched, the first rotor and the second rotor are respectively provided with the first modified section and the second modified section, and the flow-through gap is formed between the first modified section and the second rotor and between the second modified section and the first rotor.

[0008] In the above technical solution, the first rotor and the second rotor are used for compressing the gas molecules in the compression cavity through engagement and matching, and a small part of the gas molecules can pass through the flow-through gap during compression, so as to reduce the aggregation density of the gas molecules during compression, relieve the heating of the gas molecules, prevent the temperature of the gas molecules from being too high during compression, and further improve the use effect of the overall vacuum pump.

[0009] Optionally, the first modified section and the second modified section are in the shape of a circular arc.

[0010] In the above technical solution, by limiting the shape of the first modified section and the second modified section, the opening size of the flow-through gap is relatively stable during the engagement and matching of the first rotor and the second rotor.

[0011] Optionally, the first rotor is further provided with a pointed transition arc segment FG, a straight line segment GH, a transition arc segment HI, a dedendum arc segment IJ, a cycloid JK, a straight line segment KA, a addendum arc segment AB, a straight line segment BC, a transition pointed arc segment CD and a pitch circle arc segment DE connected in sequence, the first modification segment is an arc segment EF arranged between the pitch circle arc segment DE and the pointed transition arc segment FG, and the second modification segment is engaged with the pitch circle arc segment DE.

[0012] And / or, the second rotor is further provided with a pointed transition arc segment F'G', a straight line segment G'H', a transition arc segment H'I', a dedendum arc segment I'J', a cycloid J'K', a straight line segment K'A', an addendum arc segment A'B', a straight line segment B'C', a transition pointed arc segment C'D' and a pitch circle arc segment D'E' connected in sequence, the second modification segment is an arc segment E'F' arranged between the pitch circle arc segment D'E' and the pointed transition arc segment F'G', and the first modification segment is engaged with the pitch circle arc segment D'E'.

[0013] In the technical scheme, the plurality of arc segments and straight line segments are arranged to connect the first modification segment or the second modification segment to form the outer shape of the first rotor or the second rotor, so that the first rotor or the second rotor is engaged with the other rotor to realize compression of gas molecules.

[0014] Optionally, the center distance between the first rotor and the second rotor is A, the pitch circle radius of the first rotor and the second rotor is Ro, and the pitch circle distance between the first rotor and the second rotor is a.

[0015] A=2*(Ro+a).

[0016] Optionally, the addendum circle radius of the first rotor and the second rotor is Rm, the dedendum circle radius of the first rotor and the second rotor is Rg, and the reserved gap of the first rotor and the second rotor relative to the compression cavity is b.

[0017] A=Rm+Rg+b.

[0018] In the technical scheme, the dimensions of the first rotor and the second rotor are limited to ensure the compression efficiency of the gas molecules when the rotor works in the compression cavity.

[0019] Optionally, the cycloids JK and J'K' are in the shape of a cycloid, and the cycloid equation is:

[0020] X=-(Rm+b)*sin(2*t)+(A+2b)*sin(2*t);

[0021] Y=(A+2b)*cos(t)+(Rm+b)*cos(2*t);

[0022] Wherein, 0≤t≤arccos[A / (4*R)].

[0023] In the technical solution, the swing line JK and J'K' are calculated by a specific cycloid equation, so that the chamber volume of the compressed gas molecules at the end of exhaust can be optimized.

[0024] Optionally, the extension line of the straight line segment KA passes through the center of the first rotor, and the extension line of the straight line segment K'A' passes through the center of the second rotor.

[0025] In the technical solution, the straight line segments KA and K'A' are arranged, and the extension directions of the two are limited, so that the connecting cusp points of the claw-shaped rotor are reduced, the strength of the rotor is improved, and the sealing performance is optimized.

[0026] Optionally, the diameter of the circular arc segment EF is shortened by 0.1-0.3 mm compared to the diameter of the pitch circle arc segment DE, and the diameter of the circular arc segment E'F' is shortened by 0.1-0.3 mm compared to the diameter of the pitch circle arc segment D'E'.

[0027] In the technical solution, the diameter difference between the circular arc segment EF and the pitch circle arc segment DE and the diameter difference between the circular arc segment E'F' and the pitch circle arc segment D'E' are limited respectively, so that the limit pressure, power and gas temperature in the compression process can be kept in a relatively balanced state, so that the working state of the overall device is better.

[0028] Optionally, the included angle between the first connecting line connecting the end point E of the first modified segment and the center of the first rotor and the extension line of the straight line segment KA is α, and 85°≤α≤95°.

[0029] And / or, the included angle between the second connecting line connecting the end point E' of the second modified segment and the center of the second rotor and the extension line of the straight line segment K'A' is β, and 85°≤β≤95.

[0030] In the technical solution, the extension lengths of the first modified segment and the second modified segment are limited by limiting the angle range of α and β, so that the flow gap is not too long or too short, and the temperature rise relief effect of the compressed gas molecules is not affected.

[0031] Optionally, the length of the perpendicular segment between the extension line of the straight line segment BC and the center of the first rotor is d.

[0032] The cusp transition circular arc segment FG, the straight line segment GH and the transition circular arc segment HI jointly constitute a first specific curve, the cusp transition circular arc segment F'G', the straight line segment G'H' and the transition circular arc segment H'I' jointly constitute a second specific curve, the first specific curve and the straight line segment BC are conjugate curves, and the second specific curve and the straight line segment B'C' are conjugate curves, and the equation of the conjugate curves is:

[0033] x = A*sin(t) + [A-d / cos(t)]*cos(t)*sin(2*t)

[0034] y = A*cos(t) + [A-d / cos(t)]*cos(t)*cos(2*t).

[0035] In the technical scheme, the conjugate curve equations of the first specific curve and the straight line segment BC and the second specific curve and the straight line segment B'C' are limited by specific equations, so as to ensure the compression efficiency of the gas molecules by the first rotor and the second rotor. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of the drawings.

[0037] Figure 1 The working schematic diagram of the vacuum pump provided in the embodiments of the present application is shown in the figure.

[0038] Figure 2 The working schematic diagram of the vacuum pump provided in the embodiments of the present application is shown in the figure. Figure 1 The partial enlarged schematic diagram of II in the figure is shown in the figure.

[0039] Figure 3 The plane structure schematic diagram of the first rotor and the second rotor provided in the embodiments of the present application is shown in the figure.

[0040] Figure 4 The position schematic diagram of the first connecting line, the second connecting line and the center horizontal line provided in the embodiments of the present application is shown in the figure.

[0041] Figure 5 The working schematic diagram of the vacuum pump provided in the embodiments of the present application is shown in the figure. Figure 1 The partial enlarged schematic diagram of IV in the figure is shown in the figure.

[0042] Figure 6 The three-dimensional structure schematic diagram of the first rotor or the second rotor provided in the embodiments of the present application is shown in the figure.

[0043] Figure legend: 100-vacuum pump; 110-housing shell; 111-compression cavity; 120-first rotor; 121-first modified section; 122-exhaust port; 123-first connecting line; 124-center horizontal line; 130-second rotor; 131-second modified section; 132-air inlet; 133-second connecting line; 140-flowing gap. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0046] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0047] In the description of the present application, it should be noted that, if the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0048] In addition, if the terms "first", "second" and the like appear, they are only used to distinguish description, and cannot be understood as indicating or implying relative importance.

[0049] The terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0050] Unless otherwise defined, the terms of "arrangement", "connection" and the like are to be construed in a broad sense, for example, "connection" can be fixed connection, or detachable connection, or integral connection; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0052] The claw type vacuum pump is a variable volume dry vacuum pump with claw type rotor, and generally adopts multi-stage rotor in series, to form a multi-stage claw type vacuum pump. The rotors in each stage cavity are driven by motor, and the gear transmission makes the rotors realize synchronous reverse rotation in the pump cavity. The claw type rotors mesh with each other during operation, and reverse rotation. The volume between the rotors decreases and the molecular density increases during rotation. The gas is transported by compression. At the end of exhaust, the gas reaches the maximum compression state, and the temperature of the gas also reaches the highest, thereby affecting the working effect of the vacuum pump. In order to slow down the temperature rise of the pump body due to internal compression, the present application provides a vacuum pump for reducing the temperature at the end of rotor exhaust.

[0053] Please refer to Figures 1-6 The vacuum pump 100 provided in the embodiment can solve the above problems, which will be described in detail.

[0054] The vacuum pump 100 includes a containing shell 110, a first rotor 120 and a second rotor 130.

[0055] The containing shell 110 is formed with a compression cavity 111, and the first rotor 120 and the second rotor 130 are arranged in the compression cavity 111. The first rotor 120 and the second rotor 130 cooperate, and the first rotor 120 and the second rotor 130 are respectively provided with a first modified section 121 and a second modified section 131. When the first modified section 121 cooperates with the second rotor 130 and the second modified section 131 cooperates with the first rotor 120, a flow-through gap 140 is formed.

[0056] In the above technical solution, the first rotor 120 and the second rotor 130 are engaged to compress the gas molecules in the compression cavity 111, and a small part of the gas molecules can pass through the flow-through gap 140 during compression, so as to reduce the gathering density of the gas molecules during compression, relieve the heating of the gas molecules, prevent the temperature of the gas molecules from being too high during compression, and thus improve the use effect of the overall vacuum pump.

[0057] In actual work, the vacuum pump 100 can effectively alleviate the gas pressure at the end of exhaust, thereby reducing the heat generation, and can improve the stability and service life of the overall device; meanwhile, the pressure is reduced, the stress of the first rotor 120 and the second rotor 130 is reduced, and the power of the corresponding driving member is also reduced, thereby reducing the energy consumption.

[0058] It is worth noting that the first rotor 120 and the second rotor 130 can be the same structure, but they are not symmetrically arranged during meshing. Any one of the rotors can be a driving rotor, and the other can be a driven rotor.

[0059] In the embodiment, the first rotor 120 is a driving rotor, and the second rotor 130 is a driven rotor. The second rotor 130 is provided with an air inlet 132 for absorbing gas molecules, and the first rotor 120 is provided with an air outlet 122 for discharging gas molecules.

[0060] In combination Figure 3 Alternatively, the first modified section 121 and the second modified section 131 are in the shape of a circular arc, and form circular arc sections EF and E'F', respectively.

[0061] In the above technical solution, by limiting the shape of the first modified section 121 and the second modified section 131, the opening size of the flow passage 140 during the meshing of the first rotor 120 and the second rotor 130 is relatively stable.

[0062] Alternatively, the first rotor 120 is further provided with a pointed transition circular arc section FG, a straight line section GH, a transition circular arc section HI, a dedendum circular arc section IJ, a pendulum JK, a straight line section KA, an addendum circular arc section AB, a straight line section BC, a transition pointed circular arc section CD, and a pitch circle circular arc section DE, the first modified section 121 is arranged between the pitch circle circular arc section DE and the pointed transition circular arc section FG, and the second modified section 131 is meshed with the pitch circle circular arc section DE.

[0063] In the above technical solution, a plurality of circular arc sections and straight line sections are arranged to connect the first modified section 121 to form the shape of the first rotor 120, which facilitates the meshing with the second rotor 130 to compress the gas molecules.

[0064] Alternatively, the second rotor 130 is further provided with a pointed transition circular arc section F'G', a straight line section G'H', a transition circular arc section H'I', a dedendum circular arc section I'J', a pendulum J'K', a straight line section K'A', an addendum circular arc section A'B', a straight line section B'C', a transition pointed circular arc section C'D', and a pitch circle circular arc section D'E', the second modified section 131 is arranged between the pitch circle circular arc section D'E' and the pointed transition circular arc section F'G', and the first modified section 121 is meshed with the pitch circle circular arc section D'E'.

[0065] In the technical solution, the plurality of circular segments and straight line segments are arranged to connect the second modified segment 131 to form the shape of the second rotor 130, which is convenient for engaging with the first rotor 120 to realize compression of gas molecules. The first modified segment 121 engages with the pitch circle circular segment D'E', and the second modified segment 131 engages with the pitch circle circular segment DE, so as to realize transportation of the compressed gas.

[0066] Specifically, the straight line segment KA engages with the cycloid J'K', the addendum circular segment AB engages with the dedendum circular segment I'J', the straight line segment BC, the transition cusp circular segment CD, the cusp transition circular segment F'G', the straight line segment G'H', and the dedendum circular segment I'J' engage with each other, and the pitch circle circular segment DE and the circular segment EF engage with the circular segment E'F' and the pitch circle circular segment D'E', so that the transportation of the gas molecules is completed through the mutual engagement of the first rotor 120 and the second rotor 130.

[0067] Optionally, the center distance between the first rotor 120 and the second rotor 130 is A, the pitch circle radius of the first rotor 120 and the second rotor 130 is Ro, and the pitch circle distance between the first rotor 120 and the second rotor 130 is a.

[0068] A=2*(Ro+a).

[0069] Optionally, the addendum circle radius of the first rotor 120 and the second rotor 130 is Rm, the dedendum circle radius of the first rotor 120 and the second rotor 130 is Rg, and the reserved gap of the first rotor 120 and the second rotor 130 relative to the compression cavity 111 is b.

[0070] A=Rm+Rg+b.

[0071] In the technical solution, the dimensions of the first rotor 120 and the second rotor 130 are limited to ensure the compression efficiency of the gas molecules when the rotors work in the compression cavity 111.

[0072] It is worth noting that the pitch circle distance a refers to the distance between the pitch circle circular segment DE and the pitch circle circular segment D'E' when they engage with each other, and the reserved gap b refers to the distance between the addendum circular segment AB or the addendum circular segment A'B' and the inner wall of the compression cavity 111.

[0073] It is worth noting that the center of the first rotor 120 and the second rotor 130 can be understood as the center of the circle corresponding to the pitch circle arc segment DE and D'E' on the first rotor 120 and the second rotor 130, and the centers of the pitch circle arc segment DE, the addendum circle arc segment AB and the dedendum circle arc segment IJ on the first rotor 120 coincide, and the centers of the pitch circle arc segment D'E', the addendum circle arc segment A'B' and the dedendum circle arc segment I'J' on the second rotor 130 coincide; the addendum circle radius Rm can be understood as the distance between the addendum circle arc segment AB and A'B' and the corresponding center; the dedendum circle radius Rg can be understood as the distance between the dedendum circle arc segment IJ and I'J' and the corresponding center.

[0074] Optionally, the cycloid JK and the cycloid J'K' are in the shape of a cycloid, and the cycloid equation is:

[0075] X = - (Rm + b) * sin (2 * t) + (A + 2b) * sin (2 * t);

[0076] Y = (A + 2b) * cos (t) + (Rm + b) * cos (2 * t);

[0077] Wherein, 0≤t≤arccos[A / (4*R)].

[0078] In the above technical solution, the shape of the cycloid JK and J'K' is calculated by a specific cycloid equation, which can optimize the chamber volume of the gas molecules compressed at the end of the exhaust.

[0079] Optionally, the extension line of the straight line segment KA passes through the center of the first rotor 120, and the extension line of the straight line segment K'A' passes through the center of the second rotor 130. Specifically, the length of the straight line segment KA and the straight line segment K'A' is 6.6±0.5mm.

[0080] In the above technical solution, by setting the straight line segments KA and K'A', and limiting the extension direction of the two, the connecting sharp points of the claw-shaped rotor are reduced, the strength of the rotor is improved, and the sealing performance is optimized.

[0081] Optionally, the first connecting line 123 connecting the end point E of the first modified segment 121 and the center of the first rotor 120 and the extension line of the straight line segment KA form an angle α, and 85°≤α≤95°.

[0082] And / or, the second connecting line 133 connecting the end point E' of the second modified segment 131 and the center of the second rotor 130 and the extension line of the straight line segment KA form an angle β, and 85°≤β≤95°.

[0083] In the technical solution, the extension length of the first modified section 121 and the second modified section 131 is limited by limiting the angle range of alpha and beta, so that the flow gap 140 is not too long or too short, and the temperature rise relief effect of the compressed gas molecules is not affected.

[0084] Specifically, when alpha = 90° and beta = 90°, the extension length of the flow gap 140 is better, and the temperature rise relief effect of the compressed gas molecules is also better.

[0085] Alternatively, the diameter of the circular arc segment EF is shortened by 0.1-0.3mm compared to the diameter of the pitch circle arc segment DE, and the diameter of the circular arc segment E'F' is shortened by 0.1-0.3mm compared to the diameter of the pitch circle arc segment D'E'.

[0086] In the technical solution, the diameter difference between the circular arc segment EF and the pitch circle arc segment DE and the diameter difference between the circular arc segment E'F' and the pitch circle arc segment D'E' are limited respectively, so that the limit pressure, power and gas temperature during compression can be kept in a relatively balanced state, thereby making the working state of the overall device better.

[0087] It is worth noting that in order to explore the influence of the specific size difference between the circular arc segment EF and the pitch circle arc segment DE on the working effect of the overall device, a rounding test experiment was conducted, and the specific experimental data is shown in Table 1 below:

[0088] Table 1

[0089]

[0090] As can be seen from Table 1 above, the greater the diameter reduction size of the circular arc segment EF compared to the pitch circle arc segment DE, the greater the limit pressure of the pump set obtained, but the corresponding power consumption and temperature have a process of first decreasing and then increasing. Therefore, when the diameter difference between the two is 0.1-0.3mm, the working state of the overall device is better.

[0091] In actual work process, considering that the temperature change range is too large when the difference is 0.1mm and 0.2mm, the diameter of the circular arc segment EF can be shortened by 0.15-0.3mm compared to the diameter of the pitch circle arc segment DE.

[0092] Alternatively, the length of the vertical segment between the extension line of the straight line segment BC and the center of the first rotor 120 is d; the cusp transition circular arc segment FG, the straight line segment GH and the transition circular arc segment HI together form a first specific curve, the cusp transition circular arc segment F'G', the straight line segment G'H' and the transition circular arc segment H'I' together form a second specific curve, the first specific curve is a conjugate curve with the straight line segment BC in normal design, and the second specific curve is a conjugate curve with the straight line segment B'C' in normal design, and the equation of the conjugate curve is:

[0093] x = A*sin(t) + [A-d / cos(t)]*cos(t)*sin(2*t)

[0094] y = A*cos(t) + [A-d / cos(t)]*cos(t)*cos(2*t).

[0095] In the technical solution, the first specific curve and the straight line segment BC, and the second specific curve and the straight line segment B'C' are limited by specific equations, so as to ensure the compression effect of the gas molecules by the first rotor 120 and the second rotor 130.

[0096] In the embodiment, the first rotor 120 is provided with a central horizontal line 124, and when the first rotor 120 rotates to a specific angle, the angle between the extension line of the straight line segment BC and the central horizontal line 124 of the first rotor 120 can be 45°.

[0097] It is worth noting that the central horizontal line of the first rotor 120 is constant, while the straight line segment BC rotates with the first rotor 120, that is, the angle between the straight line segment BC and the central horizontal line 124 changes constantly during rotation.

[0098] However, considering that the claw-shaped rotor cannot be fully engaged in actual application, otherwise it will cause excessive compression of the gas, so that a closed cavity is formed between the rotors, resulting in increased noise and vibration of the pump set. Therefore, in the actual design process, the sharp point transition arc segment FG, the straight line segment GH and the transition arc segment HI are used instead.

[0099] The vacuum pump 100 provided in the embodiment has at least the following advantages:

[0100] (1) By arranging the first modified segment 121 and the second modified segment 131 and forming the flow-through gap 140, a small part of the gas molecules can pass through the flow-through gap 140 during compression, reducing the aggregation density of the gas molecules during compression, relieving the heating of the gas molecules, preventing the temperature of the gas molecules from being too high during compression, and improving the stability and service life of the overall device.

[0101] (2) The pressure is reduced, and the stress of the first rotor 120 and the second rotor 130 is also reduced, so the power of the driving motor is also reduced, thereby reducing energy consumption.

[0102] (3) By using a specific profile equation, the formed rotor shape has better compression effect in actual engagement working process.

[0103] (4), by limiting the diameter of the arc segment EF compared to the diameter of the pitch circle arc segment DE shortening size, to ensure that the limit pressure, power and gas temperature in the compression process can be kept in a relatively balanced state, so that the overall device working state is better.

[0104] The embodiment of the present application provides a kind of vacuum pump, it further includes driving member, driving member is used to and serve as the first rotor 120 of active rotor is connected, power source is provided by driving member, drives the rotation of first rotor 120.

[0105] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A vacuum pump, characterized by, The utility model relates to a kind of rotors, comprising: Include: Accommodation shell (110), first rotor (120) and second rotor (130); Wherein, the accommodation shell (110) is formed with compression cavity (111) inside, the first rotor (120) and the second rotor (130) are all arranged in the compression cavity (111), the first rotor (120) and the second rotor (130) cooperate, the first rotor (120) and the second rotor (130) are provided with first modified section (121) and second modified section (131) respectively, so that the first modified section (121) and the second rotor (130) cooperate and the second modified section (131) and the first rotor (120) cooperate to form flow gap (140); The first modified section (121) and the second modified section (131) are all in circular arc shape; The first rotor (120) is further provided with sharp point transition circular arc segment FG, straight line segment GH, transition circular arc segment HI, dedendum circular arc segment IJ, cycloid JK, straight line segment KA, addendum circular arc segment AB, straight line segment BC, transition sharp point circular arc segment CD and pitch circle circular arc segment DE connected in sequence, the first modified section (121) is circular arc segment EF arranged between pitch circle circular arc segment DE and sharp point transition circular arc segment FG, and the second modified section (131) is engaged with the pitch circle circular arc segment DE.

2. Vacuum pump according to claim 1, characterized in that And / or, the second rotor (130) is further provided with sharp point transition circular arc segment F'G', straight line segment G'H', transition circular arc segment H'I', dedendum circular arc segment I'J', cycloid J'K', straight line segment K'A', addendum circular arc segment A'B', straight line segment B'C', transition sharp point circular arc segment C'D' and pitch circle circular arc segment D'E' connected in sequence, the second modified section (131) is circular arc segment E'F' arranged between pitch circle circular arc segment D'E' and sharp point transition circular arc segment F'G', and the first modified section (121) is engaged with the pitch circle circular arc segment D'E'. The center distance of the first rotor (120) and the second rotor (130) is A, the pitch circle radius of the first rotor (120) and the second rotor (130) is Ro, and the pitch circle distance of the first rotor (120) and the second rotor (130) is a.

3. Vacuum pump according to claim 2, characterized in that Wherein, A=2* (Ro+a). The addendum circle radius of the first rotor (120) and the second rotor (130) is Rm, the dedendum circle radius of the first rotor (120) and the second rotor (130) is Rg, and the reserved gap of the first rotor (120) and the second rotor (130) relative to the compression cavity (111) is b.

4. Vacuum pump according to claim 3, characterized in that Wherein, A=Rm+Rg+b. The cycloid JK and the cycloid J'K' are in cycloid shape, and the equation of the cycloid is: X=- (Rm+b) *sin (2*t) + (A+2b) *sin (2*t); Y=(A+2b) *cos (t) + (Rm+b) *cos (2*t); Wherein, 0≤t≤arccos[A / (4*R)].

5. The vacuum pump of claim 1, wherein, An extension line of the straight line segment KA passes through the center of the first rotor (120), and an extension line of the straight line segment K'A' passes through the center of the second rotor (130).

6. The vacuum pump of claim 1, wherein, The diameter of the circular arc segment EF is shortened by 0.1-0.3 mm compared to the diameter of the pitch circle circular arc segment DE, and the diameter of the circular arc segment E'F' is shortened by 0.1-0.3 mm compared to the diameter of the pitch circle circular arc segment D'E'.

7. The vacuum pump of claim 1, wherein, An included angle between a first connecting line (123) connecting the end point E of the first modified segment (121) and the center of the first rotor (120) and the extension line of the straight line segment KA is α, and 85°≤α≤95°; And / or, an included angle between a second connecting line (133) connecting the end point E' of the second modified segment (131) and the center of the second rotor (130) and the extension line of the straight line segment K'A' is β, and 85°≤β≤95°.

8. A vacuum pump according to claim 3, characterized in that An extension line of the straight line segment BC and a perpendicular line segment between the center of the first rotor (120) have a length of d; The sharp point transition circular arc segment FG, the straight line segment GH and the transition circular arc segment HI jointly form a first specific curve, the sharp point transition circular arc segment F'G', the straight line segment G'H' and the transition circular arc segment H'I' jointly form a second specific curve, the first specific curve and the straight line segment BC are conjugate curves, the second specific curve and the straight line segment B'C' are conjugate curves, and equations of the conjugate curves are: x=A*sin(t)+[A-d / cos(t)]*cos(t)*sin(2*t); y=A*cos(t)+[A-d / cos(t)]*cos(t)*cos(2*t).

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