Roots vacuum pump shell and roots vacuum pump

Abstract

The utility model provides a Roots vacuum pump shell and a Roots vacuum pump, and belongs to the technical field of vacuum pumps. The Roots vacuum pump shell is provided with a left chamber and a right chamber; a plurality of circumferential grooves distributed in the axis direction of the shell are formed in the inner wall face of the left cavity and the inner wall face of the right cavity correspondingly. When backflow fluid flows to the position close to the blade top of the rotor, the backflow fluid is sucked to a low-pressure area along the circumferential grooves, repeated pressurization is conducted in the rotating process of the rotor, and jet flow is formed. The radial leakage flow between the rotor and the shell can be restrained in the suction-jet circulation process based on the circumferential grooves, meanwhile, the backflow path length of backflow fluid can be increased based on the circumferential grooves, and therefore the resistance of the leakage flow is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum pumps, and in particular relates to a Roots vacuum pump housing and a Roots vacuum pump. Background Art

[0002] As a rotary vacuum pump, Roots vacuum pump has the advantages of high pumping speed and fast start-up within a strong pressure range. It is widely used in mining, oil refining, chemical industry, chemistry and environmental protection and other fields.

[0003] In the operating mechanism of Roots vacuum pumps, the gaps between the rotors, the rotors and the pump housing, and the rotors and the end covers are inherent structural features. As the Roots rotors continue to rotate when the pump is running, the pressure on the outlet side gradually increases, forming a higher pressure area. The formation of this high-pressure area causes a portion of the compressed gas to penetrate into the low-pressure area through the above-mentioned gaps. This phenomenon is called "leakage flow". Since the compressed leakage gas has a higher temperature, it will heat the gas it passes through as it flows to the low-pressure area, causing the intake volume to expand. This effect reduces the volumetric efficiency of the pump and the mass flow rate. In addition, during the rotation of the rotor, as the outlet gas pressure accumulates, there will be significant airflow backflow shock and pulsation in the outlet area, which not only affects the smooth operation of the pump, but also limits its performance potential in various applications.

[0004] Therefore, the leakage flow at the gap between the rotor and the inner wall of the casing and the backflow impact caused by the pressure imbalance at the pump outlet have a significant impact on the efficiency and stability of the Roots vacuum pump. Utility Model Content

[0005] The present disclosure aims to solve at least one of the technical problems existing in the prior art, and provides a Roots vacuum pump housing and a Roots vacuum pump.

[0006] In one aspect of the present disclosure, a Roots vacuum pump housing is provided, wherein the Roots vacuum pump housing has a left chamber and a right chamber; wherein

[0007] The inner wall surfaces of the left chamber and the right chamber are both provided with a plurality of circumferential grooves distributed along the axial direction of the shell;

[0008] When the return fluid flows to the vicinity of the rotor blade tip, the return fluid is sucked into the low-pressure area along the circumferential groove, and is repeatedly pressurized during the rotation of the rotor to form a jet flow.

[0009] Optionally, the plurality of circumferential grooves are arranged obliquely from the pump inlet of the housing toward the pump outlet of the housing.

[0010] Optionally, the angle between the inclination direction of the circumferential groove and the height direction of the shell is less than 90°.

[0011] Optionally, two ends of the circumferential groove are respectively connected to a pump inlet and a pump outlet of the housing.

[0012] Optionally, an air inlet passage is provided on the inner side of the top wall of the housing along the axial direction thereof, the air inlet passage is connected to the pump inlet of the housing, and one end of the circumferential groove is connected to the air inlet passage;

[0013] An exhaust passage is provided inside the bottom wall of the housing and along the axial direction thereof. The exhaust passage is communicated with the pump outlet of the housing, and the other end of the circumferential groove is communicated with the exhaust passage.

[0014] Optionally, the multiple circumferential grooves in the left chamber and the multiple circumferential grooves in the right chamber are symmetrically arranged along the axial center line of the shell.

[0015] Optionally, the width of the circumferential groove is 0.05% to 15% of the inner diameter of the shell; and / or,

[0016] The depth of the circumferential groove is 0.2% to 16.7% of the inner diameter of the shell; and / or,

[0017] The distance between the front end cover plate of the housing and the circumferential groove close to the front end cover plate of the housing is 0.05% to 20% of the inner diameter of the housing; and / or

[0018] The distance between the rear end cover plate of the shell and the circumferential groove close to the rear end cover plate of the shell is 0.05% to 20% of the inner diameter of the shell.

[0019] Optionally, the distance between the front end cover plate of the shell and the circumferential groove close to the front end cover plate of the shell is the same as the distance between the rear end cover plate of the shell and the circumferential groove close to the rear end cover plate of the shell.

[0020] Optionally, the surface of the circumferential groove is provided with a friction-reducing coating.

[0021] Another aspect of the present disclosure provides a Roots vacuum pump, comprising: a left rotor, a right rotor and a housing, wherein the housing adopts the Roots vacuum pump housing described above; wherein:

[0022] The left rotor is located in the left chamber in the shell, and a plurality of left circumferential grooves distributed along the axis direction of the shell are arranged on the inner wall surface of the left chamber, and the left rotor corresponds to the plurality of left circumferential grooves;

[0023] The right rotor is located in the right chamber in the shell, and a plurality of right circumferential grooves distributed along the axis direction of the shell are arranged on the inner wall surface of the right chamber, and the right rotor corresponds to the plurality of right circumferential grooves.

[0024] The present disclosure proposes a Roots vacuum pump housing and a Roots vacuum pump. The Roots vacuum pump housing has a left chamber and a right chamber; wherein, the inner wall surfaces of the left chamber and the right chamber are both provided with a plurality of circumferential grooves distributed along the axial direction of the housing; when the reflux fluid flows to the vicinity of the rotor blade tip, the reflux fluid is sucked to the low-pressure area along the circumferential groove, and is repeatedly pressurized during the rotation of the rotor to form a jet flow. The present disclosure is based on the suction-jet cycle process of the circumferential groove, which can suppress the radial leakage flow between the rotor and the housing. At the same time, based on the setting of the circumferential groove, the reflux path length of the reflux fluid can be increased, thereby increasing the resistance of the leakage flow. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 2 It is a schematic structural diagram of a Roots vacuum pump housing with circumferential grooves according to another embodiment of the present disclosure;

[0027] Figure 3 A front view of a Roots vacuum pump housing with circumferential grooves according to another embodiment of the present disclosure;

[0028] Figure 4 For this disclosure Figure 3 Sectional view along the AA plane;

[0029] Figure 5 For this disclosure Figure 3 Sectional view along the BB plane;

[0030] Figure 6 A side view of a Roots vacuum pump housing with circumferential grooves according to another embodiment of the present disclosure;

[0031] Figure 7 For this disclosure Figure 6 Sectional view along CC plane. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0033] In some descriptions of the present disclosure, “include” or “comprises” and the like neither limit the mentioned shapes, numbers, steps, actions, operations, components and / or groups thereof, nor exclude the presence or addition of one or more other different shapes, numbers, steps, actions, operations, components and / or groups thereof.

[0034] In some descriptions of the present disclosure, unless otherwise clearly specified and limited, the terms "connected", "connected" or "fixed" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect through an intermediate medium, and may be internal connections between two elements or mutual interactions between two elements.

[0035] In some descriptions of the present disclosure, terms such as "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings and are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0036] like Figures 1 to 7 As shown, in one aspect of the present disclosure, a Roots vacuum pump housing 100 is provided, and the Roots vacuum pump housing 100 has a left chamber 110 and a right chamber 120; wherein, a plurality of left circumferential grooves 111 distributed along the axis direction of the housing are arranged on the inner wall surface of the left chamber 110, and the plurality of left circumferential grooves 111 correspond to the left rotor 210 in the left chamber 110; a plurality of right circumferential grooves 121 distributed along the axis direction of the housing are arranged on the inner wall surface of the right chamber 120, and the plurality of right circumferential grooves 121 correspond to the right rotor 220 in the right chamber 120, when the reflux fluid flows to the vicinity of the blade tops of the left rotor and the right rotor, the reflux fluid is sucked into the low-pressure area along the left circumferential grooves and the right circumferential grooves, and the reflux fluid is repeatedly pressurized during the rotation of the rotor to form a jet flow.

[0037] In this embodiment, the left circumferential groove and the right circumferential groove are equivalent to groove structures respectively opened on the inner wall surface along the circumference of the shell. Based on the groove structure, the reflux path length of the reflux fluid can be increased, thereby increasing the resistance of the leakage flow. At the same time, the radial leakage flow between the rotor and the shell can be suppressed through the suction-injection cycle process in the circumferential groove.

[0038] It should be understood that when the reflux fluid flows to the vicinity of the rotor blade tip, based on the pressure difference between the high-pressure side and the low-pressure side, the reflux fluid is sucked into the low-pressure area along the circumferential groove. Afterwards, a certain pressurization effect is generated during the rotation of the rotor. The reflux fluid is affected by the rotation of the rotor and undergoes secondary pressurization, thereby forming a jet flow, which is sprayed toward the high-pressure side, thereby reducing radial leakage caused by the pressure difference.

[0039] It should be noted that the present embodiment does not impose any specific limitation on the lengths of the left circumferential groove and the right circumferential groove. For example, in some preferred embodiments, the left circumferential groove and the right circumferential groove should extend from the top wall to the bottom wall of the shell to further increase the length of the reflux path.

[0040] It should be further explained that the present embodiment does not specifically limit the shapes of the left circumferential groove and the right circumferential groove. For example, they can be arranged in a vertical direction from the top wall to the bottom wall of the shell, or in an inclined direction from the top wall to the bottom wall of the shell.

[0041] In some preferred embodiments, Figures 1 to 5 As shown, the left circumferential groove 111 and the right circumferential groove 121 can be arranged obliquely from the pump inlet 131 of the housing to the pump outlet 141 of the housing. It should be understood that, generally speaking, the pump inlet 31 of the housing is arranged on the top wall of the housing 100, such as Figures 1 to 4 As shown, the pump outlet 141 of the shell is set on the bottom wall of the shell 00, so that the left circumferential groove 111 is inclined from the top wall of the left chamber 110 to the bottom wall, and the right circumferential groove 121 is inclined from the top wall of the right chamber 120 to the bottom wall.

[0042] In this embodiment, based on the certain inclination angle of the left circumferential groove and the right circumferential groove, the gas can flow in a specific direction in the circumferential groove, which helps to reduce the possibility of gas backflow to the low-pressure area and reduce leakage between the rotor and the end cover.

[0043] As a further preferred embodiment, Figure 5 As shown, taking the right circumferential groove as an example, there is an angle between the inclined direction of the right circumferential groove and the height direction of the shell, that is, the first angle θ between the line connecting the starting end and the terminal end of the right circumferential groove and the vertical plane of the shell along its height direction is less than 90°. In other words, the second angle between the inclined direction of the right circumferential groove and the horizontal plane of the shell is greater than 0° and less than or equal to 90°, and the first angle and the second angle are 90°.

[0044] It should be understood that when the first angle θ is 0°, the circumferential groove is vertically arranged from the top wall of the shell to the bottom wall of the shell, and when 0<θ<90°, the circumferential groove is inclinedly arranged from the top wall of the shell to the bottom wall of the shell.

[0045] As a further preferred solution, the first angle θ=30°, 45°, 60°. Correspondingly, the second angle is 60°, 45°, 30°.

[0046] It should be noted that the first angle θ between the left circumferential groove and the height direction of the shell is also preferably less than 90°, and the inclination angles between the multiple left circumferential grooves can be the same or different, as long as the multiple left circumferential grooves are spaced apart. Similarly, the inclination angles between the multiple right circumferential grooves can also be the same or different, and there is no specific limitation on this.

[0047] In some preferred embodiments, the inclination angles of the plurality of left circumferential grooves are the same, and the inclination angles of the plurality of right circumferential grooves are also the same.

[0048] Furthermore, in a conventional Roots vacuum pump, when the gas in the vacuum pump chamber is about to contact the gas at the pump outlet, that is, at the moment of the gas compression process, a large amount of fluid flows from the pump outlet into the pump chamber where the rotor is located, causing obvious backflow impact, affecting the operating stability of the vacuum pump. In view of this, the present embodiment further connects the two ends of the circumferential groove to the pump inlet and the pump outlet of the housing, respectively.

[0049] It should be noted that the present embodiment does not specifically limit the connection method between the circumferential groove and the pump inlet and the pump outlet. For example, the end of the circumferential groove may be directly connected to the pump inlet and the pump outlet, or the circumferential groove may be connected to the pump inlet and the pump outlet through other connecting channels and other structures.

[0050] For example, Figure 1 , Figure 2 and Figure 4 , Figure 7 As shown, the top wall of the housing 100 is provided with a pump inlet 131, and an air intake channel 132 is provided inside the top wall of the housing 100 and along the housing axis direction, the air intake channel 132 is connected to the pump inlet 131, and one end of the left circumferential groove 111 and the right circumferential groove 121 is connected to the pump inlet 131, so that the left circumferential groove and the right circumferential groove are connected to the pump inlet through the air intake channel. The bottom wall of the housing 100 is provided with a pump outlet 141, and an exhaust channel 142 is provided inside the bottom wall of the housing 100 and along the housing axis direction, the exhaust channel 142 is connected to the pump outlet 141, and the other end of the left circumferential groove 111 and the right circumferential groove 121 is connected to the exhaust channel 142, so that the left circumferential groove and the right circumferential groove are connected to the pump outlet through the exhaust channel. That is to say, grooves are opened along the axial direction of the top wall and the bottom wall of the shell to form an intake channel and an exhaust channel respectively, and at the same time, the two ends of the left circumferential groove and the right circumferential groove are connected to the intake channel and the exhaust channel respectively.

[0051] It is worth noting that, since the air intake channel and the exhaust channel are connected to the left circumferential groove and the right circumferential groove respectively, the air intake channel and the exhaust channel should be set in the middle area of ​​the shell top wall and the shell bottom wall, that is, the air intake channel and the exhaust channel are set at the position where the left chamber is connected to the right chamber. In addition, the air intake channel should also correspond to the position of the pump inlet. When the pump inlet is located at the position of the shell top wall close to the front end cover, the air intake channel is located on both sides of the pump inlet to meet the requirement of being connected to multiple circumferential grooves. Similarly, the exhaust channel should correspond to the position of the pump outlet. When the pump outlet is located at the position of the shell bottom wall close to the rear end cover, the exhaust channel is located on both sides of the pump outlet.

[0052] In this embodiment, based on the connection between the circumferential groove and the pump outlet section, the gas in the rotor can be brought into contact with the gas at the outlet position in advance before compression, so that the pressure of the gas in the pump during the compression process can reach a pre-balanced state with the exhaust pressure at the outlet position in advance, thereby avoiding a large amount of fluid flowing from the pump outlet into the pump chamber where the rotor is located, causing obvious reflux shock, and improving the operating stability of the vacuum pump.

[0053] Furthermore, the present embodiment does not specifically limit the correspondence between the plurality of left circumferential grooves and the plurality of right circumferential grooves. The plurality of left circumferential grooves and the plurality of right circumferential grooves may be symmetrically or asymmetrically arranged.

[0054] In some preferred embodiments, Figure 1 , Figure 2 and Figure 7 As shown, a plurality of left circumferential grooves 111 and a plurality of right circumferential grooves 121 are symmetrically arranged along the axial center line of the shell 100, that is, each left circumferential groove corresponds to each right circumferential groove one by one, and the two are symmetrically arranged along the vertical plane in the height direction of the shell, that is, the projections of the two on the vertical plane in the height direction of the shell coincide.

[0055] It should be understood that the axial center line of the shell is also the dividing line between the left chamber and the right chamber, and the left chamber and the right chamber are symmetrically arranged on both sides of the center line.

[0056] In some preferred embodiments, multiple left circumferential grooves and multiple right circumferential grooves are asymmetrically arranged along the axial center line of the shell, that is, each left circumferential groove and each right circumferential groove are alternately arranged in sequence, and their projections on the vertical plane along the height direction of the shell are staggered in sequence.

[0057] Furthermore, the present embodiment does not specifically limit the number and arrangement of the plurality of left circumferential grooves and the plurality of right circumferential grooves, and can be specifically set according to the length of the Roots vacuum pump housing. In addition, the plurality of left circumferential grooves and the plurality of right circumferential grooves can be arranged at equal intervals or at unequal intervals.

[0058] Furthermore, the present embodiment does not impose any specific limitation on the width and depth of the left circumferential groove and the right circumferential groove, as well as the distance from the front cover and the rear cover, as long as it can guide the gas to flow in a predetermined direction and perform the functions of suction and injection of the reflux fluid.

[0059] In some preferred embodiments, the width of the circumferential groove is 0.05% to 15% of the inner diameter of the shell. It should be understood that the shell of this embodiment is similar to an elliptical shell, and has two semicircular chambers in the shell. Therefore, the inner diameter of the shell referred to above should be the diameter of the corresponding semicircular chamber.

[0060] As a further preferred embodiment, the width of the left circumferential groove is 0.05% to 15% of the inner diameter of the left chamber, for example, 1%, 3%, 4.5%, 6.25%, 8%, 12%. The width of the right circumferential groove is 0.05% to 15% of the inner diameter of the right chamber, for example, 1%, 3%, 4.5%, 6.25%, 8%, 12%. Of course, the widths of the left circumferential groove and the right circumferential groove may be equal or unequal, and there is no specific limitation on this.

[0061] As a further preferred solution, Figure 1 , Figure 2 , Figure 4 and Figure 5 As shown, the width of the left circumferential groove 111 corresponds to 6.25% of the inner diameter of the left chamber 110 , and the width of the right circumferential groove 121 corresponds to 6.25% of the inner diameter of the right chamber 120 .

[0062] In other preferred embodiments, the depth of the circumferential groove is 0.2% to 16.7% of the inner diameter of the housing.

[0063] As a further preferred embodiment, the depth of the left circumferential groove is 0.2% to 16.7% of the inner diameter of the left chamber. For example, 1%, 3.125%, 5%, 7.25%, 10%, 12.5%, 14.5%, 16%. The depth of the right circumferential groove is 0.2% to 16.7% of the inner diameter of the right chamber. For example, 1%, 3.125%, 5%, 7.25%, 10%, 12.5%, 14.5%, 16%. The depths of the left circumferential groove and the right circumferential groove may be equal or unequal.

[0064] As a further preferred solution, Figure 1 , Figure 2 , Figure 4 and Figure 5 As shown, the depth of the left circumferential groove 111 corresponds to 3.125% of the inner diameter of the left chamber 110 , and the depth of the right circumferential groove 121 corresponds to 3.125% of the inner diameter of the right chamber 120 .

[0065] In other preferred embodiments, Figure 5As shown, the distance between the left circumferential groove 111 near the front end cover plate of the housing 100 and the front end cover plate of the housing 100 is the first distance d1, and similarly, the distance between the right circumferential groove 121 near the front end cover plate of the housing 100 and the front end cover plate of the housing 100 is also the first distance d1. Secondly, the distance between the left circumferential groove 111 near the rear end cover plate of the housing 100 and the rear end cover plate of the housing 100 is the second distance d2, and similarly, the distance between the right circumferential groove 121 near the rear end cover plate of the housing 100 and the rear end cover plate of the housing 100 is also the second distance d2. The first distance d1 and the second distance d2 are 0.05% to 20% of the inner diameter of the housing, for example, 2.5%, 6.25%, 8.5%, 10%, 13.5%, 15.25%, 18%, 20%.

[0066] As a further preferred solution, the first distance is equal to the second distance. That is, the distances between the left circumferential groove and the front end cover plate and the rear end cover plate of the shell are equal, and the distances between the right circumferential groove and the front end cover plate and the rear end cover plate of the shell are also equal. Figure 1 , Figure 2 , Figure 4 and Figure 5 As shown, the first distance d1 and the second distance d2 are 6.25% of the inner diameter of the housing.

[0067] Furthermore, in this embodiment, a friction-reducing coating is provided on the surface of the left circumferential groove and the right circumferential groove to reduce the gas friction coefficient and help smooth the airflow.

[0068] It should be noted that the material of the anti-friction coating is not specifically limited in this embodiment, and any material that can reduce the gas friction coefficient can be used, for example, graphene, etc.

[0069] Furthermore, the present embodiment does not specifically limit the structure of the left chamber and the right chamber. The left-side accommodation space in the shell can be defined as the left chamber, and the right-side accommodation space in the shell can be defined as the right chamber. Of course, a plurality of left-side sub-chambers can be arranged along the inner wall of the shell in the left-side accommodation space of the shell, and these left-side sub-chambers constitute the left chamber. Correspondingly, the left rotor adopts a multi-stage left rotor, and each stage of the left rotor is accommodated in a corresponding left-side sub-chamber. Similarly, a plurality of right-side sub-chambers can be arranged along the inner wall of the shell in the right-side accommodation space of the shell, and these right-side sub-chambers constitute the right chamber. Correspondingly, the right rotor adopts a multi-stage right rotor, and each stage of the right rotor is accommodated in a corresponding right-side sub-chamber. In other words, the left chamber and the right chamber can be a single large cavity structure, or a plurality of small cavity structures arranged at intervals.

[0070] It should be understood that when the left chamber includes a plurality of left sub-chambers, a corresponding left circumferential groove may be provided in each left sub-chamber, or a plurality of left circumferential grooves may be provided, which is not specifically limited and may be specifically provided according to the size of the left sub-chamber. Similarly, when the right chamber includes a plurality of right sub-chambers, a right circumferential groove or a plurality of right circumferential grooves may be provided in each right sub-chamber.

[0071] It still needs to be explained that when the left chamber and the right chamber are an integral large cavity structure, multiple left circumferential grooves and multiple right circumferential grooves can be equally spaced and distributed in the corresponding left chamber and right chamber respectively; when the left chamber and the right chamber include multiple small cavity structures, the sizes of these small cavities along the axial direction of the shell decrease step by step, so that the distribution intervals of the multiple left circumferential grooves and the multiple right circumferential grooves may not be equal.

[0072] Furthermore, the present embodiment does not make any specific limitation on the shell structure. It may be an integral shell, or it may be formed by a fixed connection between an upper shell and a lower shell, and the interior of the shell is divided into a left chamber and a right chamber, wherein the left chamber is used to accommodate the left rotor, and the right chamber is used to accommodate the right rotor, and the left rotor and the right rotor rotate in opposite directions. In this way, the gas undergoes suction, transportation and compression stages along the rotation direction of the left rotor and the right rotor, and is finally discharged from the pump outlet.

[0073] like Figure 1 As shown, another aspect of the present disclosure provides a Roots vacuum pump, which includes: a left rotor 210, a right rotor 220 and a housing 100. The housing is the Roots vacuum pump housing described above. Please refer to the above description for the specific structure, which will not be repeated here.

[0074] Specifically, Figure 1 and Figure 2 As shown, the left rotor 210 is located in the left chamber 110 in the housing 100, and the left rotor 210 corresponds to the plurality of left circumferential grooves 111. The right rotor 220 is located in the right chamber 120 in the housing 100, and the right rotor 220 corresponds to the plurality of right circumferential grooves 121. The left rotor 210 and the right rotor 220 rotate in opposite directions around their respective rotation axes. For example, the left rotor 210 rotates counterclockwise along its rotation axis (such as Figure 1 The right rotor 220 rotates in a clockwise direction (eg, Figure 1 The left rotor 210 and the right rotor 220 rotate in the Y direction, and the axes of the rotating shafts are arranged parallel to each other.

[0075] It should be understood that both the left rotor and the right rotor include a corresponding rotating shaft and a rotor component arranged on the rotating shaft. The rotor component can be a two-leaf rotor component with an 8-shaped cross-section, or a three-leaf rotor component with a Y-shaped cross-section. Of course, rotor components with other numbers of blades can also be used, and there is no specific limitation on this.

[0076] It should be noted that the present embodiment does not impose any specific restrictions on the materials of the housing, the left rotor and the right rotor. For example, high-nickel alloy materials with high strength and wear resistance and corrosion resistance may be used.

[0077] In this embodiment, by providing circumferential grooves on the inner wall of the shell, the length of the reflux path of the reflux fluid can be increased, thereby increasing the resistance to the leakage flow. When the gas flows to the rotor blade tip area, the radial leakage driven by the pressure difference is reduced through the suction and injection flow mechanism in the circumferential grooves. Furthermore, when the Roots vacuum pump is operating normally, the gas can flow along the inner wall of the shell with circumferential grooves at a certain angle, and the gas can be guided to a specific direction, which helps to reduce the possibility of gas reflux to the low-pressure area. In addition, these circumferential grooves not only help to smooth the airflow, but also make the pressure of the gas in the pump during the compression process reach a pre-balanced state with the exhaust pressure at the outlet position in advance, which can reduce the pressure fluctuation caused by the sudden change of direction of the airflow and improve the operating stability of the Roots vacuum pump.

[0078] Furthermore, based on the Roots vacuum pump structure given above, its working method includes the following specific steps S1 to S4:

[0079] S1, the left rotor and the right rotor rotate in opposite directions driven by their respective rotating shafts, and the gas flows into the left chamber and the right chamber in the shell from the pump inlet.

[0080] S2. During the process of gas rotating with the left and right rotors, when the return fluid flows to the vicinity of the blade tips of the left and right rotors, the return fluid is sucked into the low-pressure area along the left circumferential groove and the right circumferential groove, and is repeatedly pressurized as the left and right rotors rotate, forming a jet flow.

[0081] It should be understood that when the reflux fluid flows to the vicinity of the blade tips of the left and right rotors, the reflux fluid can enter the left circumferential groove and the right circumferential groove structure due to the pressure difference, so as to re-inject the part of the reflux fluid into the low-pressure side of the left and right rotors, and then the part of the reflux fluid is secondary pressurized under the influence of the rotation of the rotor, further forming a jet flow and ejected in the direction of the high-pressure side. In other words, the suction-injection cycle formed by the circumferential groove allows the reflux fluid to be ejected and flow out, effectively suppressing the radial leakage flow between the rotor and the housing.

[0082] It is easy to understand that when the fluid flows back to the cavity portion, the left circumferential groove and the right circumferential groove can also increase the path length of the backflow, thereby increasing the resistance of the leakage flow and further reducing radial leakage.

[0083] It should be noted that the cavity portion formed by the rotor and the shell refers to the closed area formed by the rotor and the inner wall of the shell during the rotation of the rotor. For example, taking the right rotor component with an 8-shaped profile as an example, when the right rotor rotates to the point where the center line along the length direction of the rotor component is 60° to 120° in the width direction of the shell, the right rotor and the inner wall of the shell are in a sealed state.

[0084] S3. After the gas undergoes the inhalation and displacement process, when the gas is connected to the pump outlet, the gas near the pump outlet position contacts the pump outlet gas in advance through the left circumferential groove and the right circumferential groove, so that the gas before the compression process and the pump outlet gas pressure reach a pre-balance.

[0085] It should be further explained that when the right rotor rotates to a point where the center line along the length of the impeller is 120° to the width of the casing, the right circumferential groove can enable the gas in the sealing area to contact the gas at the outlet in advance, so that the gas pressure near the outlet is close to the exhaust pressure, thereby making the pressure on both sides reach a pre-balanced state, reducing the pump outlet pressure, avoiding vacuum pump fluctuations, and improving the operating mobility of the vacuum pump.

[0086] S4. Gas is discharged from the pump outlet.

[0087] The present disclosure proposes a Roots vacuum pump housing and a Roots vacuum pump, which have the following beneficial effects compared with the prior art: the present disclosure provides a circumferential groove on the inner wall of the housing chamber, thereby not only increasing the length of the reflux path and improving the resistance of the leakage flow, but also reducing the radial leakage caused by the pressure difference through the suction-injection cycle process in the groove, and reducing the leakage between the rotor and the housing; secondly, the circumferential groove also helps to smooth the airflow, so that the gas flows in a predetermined direction, avoids the gas from flowing back to the low-pressure area, and further reduces the leakage between the rotor and the housing end wall; further, based on the connection between the circumferential groove and the pump outlet, it can also reduce the pressure fluctuation caused by the sudden change of direction of the airflow, which helps to improve the operating stability of the Roots vacuum pump, ensure the reliability and efficiency of the vacuum pump under various working conditions, and provide a larger space for the application scope and development potential of the vacuum pump.

[0088] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure 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 substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A Roots vacuum pump housing, characterized in that: The Roots vacuum pump housing has a left chamber and a right chamber; wherein, The inner wall surfaces of the left chamber and the right chamber are both provided with a plurality of circumferential grooves distributed along the axial direction of the shell; When the return fluid flows to the vicinity of the rotor blade tip, the return fluid is sucked into the low-pressure area along the circumferential groove, and is repeatedly pressurized during the rotation of the rotor to form a jet flow.

2. The Roots vacuum pump housing according to claim 1, characterized in that: The plurality of circumferential grooves are arranged obliquely from the pump inlet of the housing toward the pump outlet of the housing.

3. The Roots vacuum pump housing according to claim 2, characterized in that: The angle between the inclined direction of the circumferential groove and the height direction of the shell is less than 90°.

4. The Roots vacuum pump housing according to claim 1, characterized in that: Two ends of the circumferential groove are respectively connected to the pump inlet and the pump outlet of the housing.

5. The Roots vacuum pump housing according to claim 4, characterized in that: An air inlet passage is provided on the inner side of the top wall of the housing along the axial direction thereof, the air inlet passage is connected to the pump inlet of the housing, and one end of the circumferential groove is connected to the air inlet passage; An exhaust passage is arranged on the inner side of the bottom wall of the shell along the axial direction thereof, the exhaust passage is communicated with the pump outlet of the shell, and the other end of the circumferential groove is communicated with the exhaust passage.

6. The Roots vacuum pump housing according to any one of claims 1 to 5, characterized in that: The width of the circumferential groove is 0.05% to 15% of the inner diameter of the shell; and / or, The depth of the circumferential groove is 0.2% to 16.7% of the inner diameter of the shell.

7. The Roots vacuum pump housing according to any one of claims 1 to 5, characterized in that: The distance between the front end cover plate of the housing and the circumferential groove close to the front end cover plate of the housing is 0.05% to 20% of the inner diameter of the housing; and / or The distance between the rear end cover plate of the shell and the circumferential groove close to the rear end cover plate of the shell is 0.05% to 20% of the inner diameter of the shell.

8. The Roots vacuum pump housing according to claim 7, characterized in that: The distance between the front end cover plate of the shell and the circumferential groove close to the front end cover plate of the shell is the same as the distance between the rear end cover plate of the shell and the circumferential groove close to the rear end cover plate of the shell.

9. The Roots vacuum pump housing according to any one of claims 1 to 5, characterized in that: The surface of the circumferential groove is provided with a friction reducing coating.

10. A Roots vacuum pump, characterized in that: The Roots vacuum pump comprises: a left rotor, a right rotor and a housing, and the housing is a Roots vacuum pump housing as claimed in any one of claims 1 to 9; wherein: The left rotor is located in the left chamber in the shell, and a plurality of left circumferential grooves distributed along the axis direction of the shell are arranged on the inner wall surface of the left chamber, and the left rotor corresponds to the plurality of left circumferential grooves; The right rotor is located in the right chamber in the shell, and a plurality of right circumferential grooves distributed along the axis direction of the shell are arranged on the inner wall surface of the right chamber, and the right rotor corresponds to the plurality of right circumferential grooves.

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