Roots vacuum pump

Abstract

The utility model provides a roots vacuum pump. The roots vacuum pump comprises a shell, a first rotor and a second rotor, an accommodating cavity is formed in the shell; the first rotor and the second rotor are both arranged in the containing cavity and rotate in the containing cavity in a meshed mode. The first rotor rotates around a first rotating shaft in a first direction, the second rotor rotates around a second rotating shaft in a second direction, the first rotating shaft and the second rotating shaft are parallel to each other, and the first direction is opposite to the second direction; a first groove is formed in the blade top of the first rotor, and a second groove is formed in the blade top of the second rotor. The Roots vacuum pump has the advantages that the design is reasonable, leakage between the first rotor or the second rotor and the shell can be effectively restrained, and the operation stability of the Roots vacuum pump is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of vacuum pumps, and particularly relates to a Roots vacuum pump. Background Art

[0002] A Roots vacuum pump is a positive-displacement pump widely used in multiple industrial fields. Its working principle is based on two meshing rotors rotating in the pump chamber, thereby forming a low pressure at the inlet to suck in gas and discharging the gas at high pressure through the outlet. Due to its simple structure, no need for lubricating oil, high volumetric efficiency, and flexible installation method, the Roots vacuum pump is particularly suitable for occasions requiring large flow rates and medium vacuum degrees. However, despite many advantages of the Roots pump, its performance is often limited by a key factor, that is, the leakage flow between the rotor and the inner wall surface of the pump housing.

[0003] During the operation of the Roots pump, a certain gap must be maintained between the rotor and the pump housing to allow for thermal expansion and prevent contact wear. Although these gaps are necessary, they also become channels for gas to leak from the high-pressure area to the low-pressure area. This leakage flow not only reduces the effective pumping speed of the pump, lowers the overall efficiency, but also increases energy consumption and operating costs. In addition, when the leaked gas re-enters the suction port of the pump, it is usually at a relatively high temperature, which causes the volume of the sucked-in gas to increase, further reducing the volumetric efficiency of the pump.

[0004] To improve this situation, researchers and engineers have proposed various solutions to reduce the leakage flow, including optimizing the rotor profile design, using seals or coatings to reduce the gap, and improving the pump housing design, etc. Nevertheless, the prior art still faces some challenges, such as improving machining accuracy, controlling the influence of thermal deformation on the gap, and enhancing the sealing performance without affecting assembly and maintenance.

[0005] To suppress the leakage flow between the rotor of the Roots vacuum pump and the inner wall surface of the pump housing, the prior art generally adopts innovative designs of improving the rotor profile, surface coating technology, and sealing structure. For example, adopting an arc-involute-arc type rotor profile aims to reduce the gap leakage during the rotation of the rotor, and some advanced surface coating technologies attempt to reduce the slip flow of gas molecules by reducing the surface roughness, thereby reducing leakage. In addition, some designs also attempt to introduce new sealing structures, such as using magnetic levitation technology or mechanical seals to reduce the leakage flow.

[0006] However, these existing technologies still have deficiencies. First, although the improved rotor profiles can reduce leakage to a certain extent, they have high requirements for machining accuracy, and under high-temperature working conditions, the thermal deformation of the rotor may cause the effect to be greatly reduced. Second, although the surface coating technology can reduce leakage to a certain degree, the durability of the coating and the performance stability under high-speed rotation and high-temperature environments have not been fully resolved. Finally, although magnetic levitation technology and mechanical seals provide new solutions, the complexity and cost of these technologies limit their wide application.

[0007] Therefore, for the leakage flow problem between the rotor of a Roots vacuum pump and the inner side wall surface of the pump housing, there is an urgent need in this technical field for a Roots vacuum pump that can not only effectively reduce the leakage flow, improve the pumping speed and efficiency of the pump, but also does not have overly high requirements for existing machining and assembly technologies, so as to facilitate practical application and maintenance. Summary of the Utility Model

[0008] The utility model aims to solve at least one of the technical problems existing in the prior art and provides a new technical solution for a Roots vacuum pump.

[0009] According to one aspect of the present application, a Roots vacuum pump is provided, including:

[0010] A housing, an accommodation cavity is formed inside the housing;

[0011] A first rotor and a second rotor, the first rotor and the second rotor are both arranged in the accommodation cavity and meshingly rotate in the accommodation cavity. The first rotor rotates around a first rotation axis in a first direction, and the second rotor rotates around a second rotation axis in a second direction; the first rotation axis and the second rotation axis are parallel to each other, and the first direction and the second direction are opposite;

[0012] A first groove is provided at the tip of the first rotor, and a second groove is provided at the tip of the second rotor.

[0013] Optionally, both the first rotor and the second rotor are two-lobe rotors, and the first groove is provided at the tip of each lobe of the first rotor, and the second groove is provided at the tip of each lobe of the second rotor.

[0014] Optionally, both the first rotor and the second rotor are 8-shaped lobe profile rotors, and the first groove or the second groove is provided at the positions of the two opposite vertices of the 8-shaped lobe profile rotor. When the first rotor or the second rotor is vertically arranged, the second rotor or the first rotor is horizontally arranged, and when the first rotor and the second rotor rotate, the tip region of each rotor far from the other rotor forms a seal with the inner side wall of the housing.

[0015] Optionally, both the first rotor and the second rotor are three - lobe rotors. Each lobe tip of the first rotor is provided with the first groove, and each lobe tip of the second rotor is provided with the second groove.

[0016] Optionally, an air inlet is provided on the upper side wall of the housing, and an air outlet is provided on the lower side wall; the opening area of the air inlet is greater than or equal to the opening area of the air outlet.

[0017] Optionally, the depths of the first groove and the second groove are respectively 0.05 mm to 20 mm.

[0018] Optionally, the widths of the first groove and the second groove are respectively greater than 1 mm.

[0019] Optionally, the axial length of the first groove is the same as the axial length of the first rotor, and the axial length of the second groove is the same as the axial length of the second rotor.

[0020] Optionally, the materials of the housing, the first rotor, and the second rotor are all high - nickel alloy materials.

[0021] Optionally, the extending direction of the first groove is the same as the extending direction of the first rotation axis; the extending direction of the second groove is the same as the extending direction of the second rotation axis.

[0022] One technical effect of the present application is that:

[0023] In the embodiment of the present application, when the fluid moves to the gap between the first rotor or the second rotor and the inner side wall of the housing (i.e., the pump housing), originally, under the action of the pressure difference, the gas flowing back from the high - pressure side to the low - pressure side along the gap forms a vortex in the first groove or the second groove, reducing the flow - through area of the lobe tip gap of the first rotor or the second rotor and reducing the back - flowing gas.

[0024] Therefore, this Roots vacuum pump is not only beneficial to suppressing the leakage between the first rotor or the second rotor and the housing, but also has a certain beneficial effect on suppressing the leakage between the first rotor and the second rotor when the first rotor or the second rotor runs to a specific position, improving the flow pattern inside the pump and enhancing the operation stability of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a Roots vacuum pump according to an embodiment of the present invention;

[0026] Figure 2 It is a schematic structural diagram of the first rotor and the second rotor of a Roots vacuum pump according to an embodiment of the present invention;

[0027] Figure 3The top view of a Roots vacuum pump according to an embodiment of the present utility model;

[0028] Figure 4 is Figure 3 the sectional view taken along the A-A plane in

[0029] Figure 5 is Figure 3 the sectional view taken along the B-B plane in

[0030] Figure 6 The schematic structural diagram of the first groove and the second groove of a Roots vacuum pump according to an embodiment of the present utility model;

[0031] Figure 7 The enlarged detail schematic diagram of the first groove of a Roots vacuum pump according to an embodiment of the present utility model;

[0032] Figure 8 is the flow field distribution diagram at the gap E in the prior art and the gap F in the present application.

[0033] In the figure: 1. Housing; 101. Accommodating cavity; 2. First rotor; 21. First rotating shaft; 22. First groove; 3. Second rotor; 31. Second rotating shaft; 32. Second groove; 4. Air inlet; 5. Exhaust port. Detailed implementation manners

[0034] Now, various exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps set forth in these embodiments, numerical expressions and values do not limit the scope of the present application.

[0035] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0036] The terms "first" and "second" in the description and claims of the present application may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, "a plurality of" means two or more. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / " generally means an "or" relationship between the associated objects before and after.

[0037] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.

[0038] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0039] According to one aspect of the present application, referring to Figures 1 to 8 , a Roots vacuum pump is provided, including:

[0040] Referring to Figure 1 and Figure 4 , a housing 1, an accommodation cavity 101 is formed inside the housing 1;

[0041] A first rotor 2 and a second rotor 3, the first rotor 2 and the second rotor 3 are both arranged in the accommodation cavity 101 and rotate meshingly in the accommodation cavity. The first rotor 2 rotates around a first rotation axis 21 in a first direction, and the second rotor 3 rotates around a second rotation axis 31 in a second direction. For example, the first rotor 2 is rotationally connected to the housing 1 through the first rotation axis 21, and the second rotor 3 is rotationally connected to the housing 1 through the second rotation axis 31; the first rotation axis 21 and the second rotation axis 31 are parallel to each other. It should be noted that the term "parallel to each other" here should be understood in a broad sense. Considering manufacturing and installation errors, the central axis of the first rotation axis 21 and the central axis of the second rotation axis 31 are allowed to show a certain angle of inclination within the error range, and such an inclination is also allowed; the first direction and the second direction are opposite;

[0042] Referring to Figure 2 , Figure 6 and Figure 7 , a first groove 22 is provided at the blade tip of the first rotor 2, and a second groove 32 is provided at the blade tip of the second rotor 3;

[0043] When the first rotor 2 and the second rotor 3 rotate, the first rotor 2 forms a seal with the inner side wall of the housing 1 through the tip region of the first rotor 2, and at the same time, the second rotor 3 forms a seal with the inner side wall of the housing 1 through the tip region of the second rotor 3.

[0044] In the embodiment of the present application, when the fluid moves to the gap between the first rotor 2 or the second rotor 3 and the inner side wall of the housing 1 (i.e., the pump housing), originally under the action of the pressure difference, the reflux gas flowing from the high-pressure side to the low-pressure side along the gap forms a vortex in the first groove 22 or the second groove 32, reducing the flow area of the tip clearance of the first rotor 2 or the second rotor 3 and reducing the reflux gas.

[0045] Therefore, this Roots vacuum pump is not only beneficial to suppressing the leakage between the first rotor 2 or the second rotor 3 and the housing 1, but also has a certain beneficial effect on suppressing the leakage between the first rotor 2 and the second rotor 3 when the first rotor 2 or the second rotor 3 runs to a specific position, improving the flow state inside the pump and enhancing the operating stability of the pump.

[0046] Optionally, both the first rotor 2 and the second rotor 3 are two-lobe rotors, and the first groove 22 is provided at each tip of the first rotor 2, and the second groove 32 is provided at each tip of the second rotor 3.

[0047] In the above embodiment, the flow state inside the pump is improved, which is beneficial to better suppressing the leakage between the first rotor or the second rotor and the housing, and enhancing the operating stability of the pump.

[0048] Optionally, referring to Figure 4 , both the first rotor 2 and the second rotor 3 are 8-shaped lobe profile rotors, and the first groove 22 or the second groove 32 is provided at the relative two vertex positions of the 8-shaped lobe profile rotor. When the first rotor 2 or the second rotor 3 is vertically arranged, the second rotor 3 or the first rotor 2 is horizontally arranged, and when the first rotor 2 and the second rotor 3 rotate, the tip region of each rotor far from the other rotor forms a seal with the inner side wall of the housing 1.

[0049] In the above embodiment, through the 8-shaped lobe profile rotor and the first groove 22 or the second groove 32 provided at the relative two vertex positions of the 8-shaped lobe profile rotor, it helps to further improve the flow state inside the pump, thereby better suppressing the leakage between the first rotor or the second rotor and the housing, and enhancing the operating stability of the pump.

[0050] Exemplarily, the first rotor 2 is provided with a first groove 22 (also known as a blade tip groove) at two relative vertex positions (also known as the top of the profile line) of the rotor with an 8-shaped blade profile. At the same time, the second rotor 2 is provided with a second groove 32 (also known as a blade tip groove) at two relative vertex positions (also known as the blade tip groove). The design of the first groove 22 or the second groove 32 includes determining the profile line position where the first groove 22 or the second groove 32 is located. For example, the center of gravity of the first rotor 2 is determined on the cross section of the first rotor 2, and the intersection of the center line of the cross section passing through the center of gravity and the arc-shaped line of the two relative vertex positions of the 8-shaped blade profile of the first rotor 2 is determined as the starting point. A groove is vertically opened along the center line toward the center of gravity of the first rotor 2 with the same size on the left and right along the starting point, and the center point of the blade tip groove is determined according to the groove depth position. Similarly, the design of the second groove 32 of the second rotor 3 is the same as the first groove 22 of the first rotor 2, which will not be repeated here.

[0051] In other embodiments, the first rotor 2 is provided with a plurality of first grooves 22 at two relative apex positions (i.e., the top of the profile line) of the rotor with the figure-eight blade profile, and the plurality of first grooves are symmetrically arranged along the cross-sectional center line of the first rotor 2. The second rotor 3 is provided with a plurality of second grooves 32 at two relative apex positions (i.e., the top of the profile line) of the rotor with the figure-eight blade profile, and the plurality of second grooves 32 are symmetrically arranged along the cross-sectional center line of the second rotor 3.

[0052] Optionally, both the first rotor 2 and the second rotor 3 are three-blade rotors, each blade top of the first rotor 2 is provided with the first groove 22 , and each blade top of the second rotor 3 is provided with the second groove 32 .

[0053] Exemplarily, the number of the first grooves 22 and the number of the second grooves 32 are both three. Further, the cross section of the first rotor 2 perpendicular to the first rotation axis 21 presents a "Y"-shaped lobe profile, and the cross section of the second rotor 3 perpendicular to the second rotation axis 31 presents a "Y"-shaped lobe profile.

[0054] In the above implementation, the Roots vacuum pump has a higher compression ratio, and is suitable for occasions requiring higher gas delivery pressure.

[0055] Alternatively, see Figure 5 The upper side wall of the shell 1 is provided with an air inlet 4, and the lower side wall is provided with an exhaust port 5; the opening area of ​​the air inlet 4 is greater than or equal to the opening area of ​​the exhaust port 5.

[0056] In the above embodiment, it is helpful to compress and transport the gas by the relative movement of the first rotor 2 and the second rotor 3 in the housing 1 .

[0057] In a specific embodiment, after the roots vacuum pump is started and operated, gas flows in from the air inlet 4 and is transported by the first rotor 2 and the second rotor 3 rotating in opposite directions. When the gas in the pump moves to the air flow channel, referring to Figure 8 At point E in, since the tip of the first rotor 2 and the second rotor 3 is not provided with a tip groove structure, at the gap between the first rotor 2 and the second rotor 3 and between the first rotor 2 or the second rotor 3 and the housing 1, under the action of the pressure difference, the fluid will flow along the gap from the high-pressure side to the low-pressure side, causing the gas in the pump to flow back, blocking the gas flow, and reducing the pumping speed of the pump.

[0058] Referring to Figure 8 At point F in, after the tip of the first rotor 2 or the second rotor 3 is grooved in the embodiment of the present application, the tip leakage flow generates a large-area entrainment to form a vortex in the first groove 22 or the second groove 32, and the vortex develops along the blade height direction towards the gap, reducing the flow area of the tip gap, thereby reducing the leakage flow rate.

[0059] Optionally, the depths of the first groove 22 and the second groove 32 are respectively 0.05 mm to 20 mm. This helps the tip leakage flow to generate a large-area entrainment to form a vortex in the first groove 22 or the second groove 32, effectively reducing the flow area of the tip gap, thereby reducing the leakage flow rate.

[0060] Optionally, the widths of the first groove 22 and the second groove 32 are respectively greater than 1 mm. This helps the tip leakage flow to generate a large-area entrainment to form a vortex in the first groove 22 or the second groove 32, thereby effectively reducing the flow area of the tip gap, and further reducing the leakage flow rate.

[0061] Optionally, the axial length of the first groove 22 is the same as the axial length of the first rotor 2, and the axial length of the second groove 32 is the same as the axial length of the second rotor 3. That is, the first groove 22 covers the entire axial direction of the tip of the first rotor 2, and the second groove 32 covers the entire axial direction of the tip of the second rotor 3.

[0062] In the above embodiment, it helps to greatly reduce the leakage flow rate, thereby ensuring the functional stability of the roots vacuum pump.

[0063] Optionally, the extending direction of the first groove 22 is the same as the extending direction of the first rotating shaft 21; the extending direction of the second groove 32 is the same as the extending direction of the second rotating shaft 32. This helps to form a vortex in the first groove 22 or the second groove 32 better, reduces the flow area of the tip gap of the first rotor 2 or the second rotor 3, and reduces the reflux gas.

[0064] Optionally, the materials of the housing 1, the first rotor 2, and the second rotor 3 are all high-nickel alloy materials.

[0065] In the above embodiments, the material strength of the housing 1, the first rotor 2, and the second rotor 3 is relatively high, which helps to ensure the safe and stable operation of the Roots vacuum pump.

[0066] Furthermore, the housing 1 can be detachably connected by a plurality of parts. For example, the connection method can be fixed connection through a flange and bolts, so as to facilitate disassembly and installation.

[0067] The working principle of the Roots vacuum pump according to the embodiment of the present application is as follows:

[0068] Step S1, the gas flows into the accommodation cavity 101 from the air inlet 4;

[0069] Step S2, as the first rotor 2 and the second rotor 3 rotate in opposite directions, the gas also continuously moves as the position of the cavity changes;

[0070] Step S3, when the fluid moves to the gap between the first rotor 2 or the second rotor 3 and the housing 1, originally under the action of the pressure difference, the gas flowing back from the high-pressure side to the low-pressure side along the gap forms a vortex in the tip groove (i.e., the first groove 22 or the second groove 32), reducing the flow area of the tip clearance and reducing the gas flowing back.

[0071] Step S4, the gas is discharged from the air outlet 5.

[0072] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention, and the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A Roots vacuum pump, characterized in that: include: A housing, wherein an accommodating cavity is formed inside the housing; A first rotor and a second rotor, wherein the first rotor and the second rotor are both disposed in the accommodating cavity and mesh and rotate in the accommodating cavity, the first rotor rotates in a first direction around a first rotation axis, and the second rotor rotates in a second direction around a second rotation axis; the first rotation axis and the second rotation axis are parallel to each other, and the first direction and the second direction are opposite; The blade tip of the first rotor is provided with a first groove, and the blade tip of the second rotor is provided with a second groove.

2. The Roots vacuum pump according to claim 1, characterized in that: The first rotor and the second rotor are both two-blade rotors, each blade top of the first rotor is provided with the first groove, and each blade top of the second rotor is provided with the second groove.

3. The Roots vacuum pump according to claim 2, characterized in that: The first rotor and the second rotor are both rotors with an 8-shaped blade profile, and the first groove or the second groove is arranged at two relative vertex positions of the 8-shaped blade profile rotor. When the first rotor or the second rotor is arranged vertically, the second rotor or the first rotor is arranged horizontally, and when the first rotor and the second rotor rotate, the blade top area of ​​each rotor away from the other rotor forms a seal with the inner wall of the casing.

4. The Roots vacuum pump according to claim 1, characterized in that: The first rotor and the second rotor are both three-blade rotors, each blade top of the first rotor is provided with the first groove, and each blade top of the second rotor is provided with the second groove.

5. The Roots vacuum pump according to claim 1, characterized in that: The upper side wall of the shell is provided with an air inlet, and the lower side wall is provided with an exhaust port; the opening area of ​​the air inlet is greater than or equal to the opening area of ​​the exhaust port.

6. The Roots vacuum pump according to claim 1, characterized in that: The depths of the first groove and the second groove are respectively 0.05 mm to 20 mm.

7. The Roots vacuum pump according to claim 1, characterized in that: The width of the first groove and the second groove is respectively greater than 1 mm.

8. The Roots vacuum pump according to claim 1, characterized in that: The axial length of the first groove is the same as the axial length of the first rotor, and the axial length of the second groove is the same as the axial length of the second rotor.

9. The Roots vacuum pump according to claim 1, characterized in that: The shell, the first rotor, and the second rotor are all made of high-nickel alloy materials.

10. The Roots vacuum pump according to claim 1, characterized in that: An extending direction of the first groove is consistent with an extending direction of the first rotation axis; an extending direction of the second groove is consistent with an extending direction of the second rotation axis.

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