A multi-stage Roots vacuum pump exhaust structure

Abstract

This utility model discloses a multi-stage Roots vacuum pump exhaust structure, belonging to the field of vacuum pump technology. Addressing the problem of motor overload during the start-up phase in existing technologies, this utility model constructs a graded pressure-response exhaust path by setting a first upper cavity and a second upper cavity on the working plate, each with an independent return and exhaust port, combined with a lower cavity channel below them. When the gas reaches a certain pressure, it opens the first valve core through the first inlet of the secondary rotor, and the gas is discharged after two stages of compression. When the pressure is normal, the gas is compressed by each stage of rotors and passes through the second inlet, opening the second valve core for normal exhaust. The main channel on the lower surface of the working plate converges the exhaust ports of each stage and discharges them uniformly from the main outlet on the side wall, simplifying external pipeline connections.

Description

Technical Field

[0001] This utility model belongs to the field of vacuum pump technology, specifically relating to an exhaust structure for a multi-stage Roots vacuum pump. Background Technology

[0002] A Roots vacuum pump is a positive displacement pump. Its core working principle involves a pair of meshing lobe-shaped rotors rotating synchronously in opposite directions within the pump chamber, creating periodic volume changes to achieve gas intake, transport, and discharge. Because the rotors maintain micron-level gaps rather than contact with each other, and between the rotors and the pump casing, this non-contact design enables oil-free and clean pumping processes, making it widely used in industries with extremely high cleanliness requirements, such as semiconductors, photovoltaics, chemicals, and pharmaceuticals. To achieve higher vacuum levels and greater pumping efficiency, single-stage Roots pumps are often insufficient. Therefore, multi-stage Roots vacuum pumps have been developed, which involve connecting multiple Roots pump units in series. The gas is compressed stage by stage within the series-connected pump chambers, ultimately reaching the pressure required for direct atmospheric discharge.

[0003] However, this multi-stage series structure also introduces new technical challenges. The most prominent problem occurs during the pump startup phase or under conditions of high inlet pressure. At this time, a large amount of gas rushes into the first-stage compression chamber and is rapidly compressed. In traditional multi-stage Roots pump designs, gas must pass through all compression stages sequentially before finally being discharged from the exhaust port of the last stage. This means that in the initial startup phase, the high-pressure gas is forcibly pushed by the preceding rotor to subsequent stages, causing the pressure in the preceding compression chamber to rise sharply in a very short time. This sudden increase in pressure directly translates into a doubling of the required drive torque for the rotor, causing the drive motor to face a huge overload impact at startup. If the motor is under this overload state for a long time or frequently, it will not only trigger overheat protection and shorten the motor's life, but in severe cases, it may even cause the pump set to fail to start normally, affecting the stability and reliability of the entire vacuum system. Although there are some improvement attempts in the industry, such as optimizing the rotor profile to reduce the compression ratio or adding complex bypass relief valves to the system, these solutions are often complex in structure, expensive, or have insufficient response speed to effectively alleviate the transient overload problem. Therefore, finding an interstage pressure regulation and venting solution that is integrated inside the pump body, has a rapid response, and is simple and reliable in structure has become the key to improving the performance and reliability of multistage Roots pumps.

[0004] This invention attempts to solve or at least alleviate the above-mentioned problems by providing a multi-stage Roots vacuum pump exhaust structure to achieve interstage exhaust. Utility Model Content

[0005] In view of one or more of the above-mentioned defects or improvement needs of the prior art, this utility model provides a multi-stage Roots vacuum pump exhaust structure, which has the advantage of improving motor overload.

[0006] To achieve the above objectives, this utility model provides a multi-stage Roots vacuum pump exhaust structure, including a vacuum pump body and an exhaust assembly disposed at the bottom of the vacuum pump body. The exhaust assembly includes a working plate and a cover plate disposed at its bottom. The upper surface of the working plate has a first upper cavity and a second upper cavity. The bottom surface of the first upper cavity is provided with an independent first return port and a first outlet. The bottom surface of the second upper cavity is provided with an independent second return port and a second outlet. A first inlet is disposed next to the first upper cavity, and a second inlet is disposed next to the second upper cavity. The lower surface of the exhaust assembly has a first lower cavity connecting the first inlet and the first return port, and a second lower cavity connecting the second inlet and the second return port. A first valve core is placed above the first return port, and a second valve core is placed above the second return port.

[0007] As a further improvement of this utility model, a main channel connecting the first air outlet and the second air outlet is opened on the lower surface of the working plate, and a main outlet connecting the main channel is opened on the side wall of the working plate.

[0008] As a further improvement of this utility model, a first guide seat is provided above the first return air port to connect to the first return air port, and a second guide seat is provided above the second return air port to connect to the second return air port. The first valve core is placed in the first guide seat, and the second valve core is placed in the second guide seat.

[0009] As a further improvement of this utility model, the first valve core and the second valve core are spherical in shape.

[0010] As a further improvement of this utility model, the first guide seat and the second guide seat are shaped as inner conical surfaces.

[0011] As a further improvement of this utility model, a sealing plate is detachably provided on the top of the first upper cavity and the second upper cavity.

[0012] As a further improvement of this utility model, the upper surface of the cover plate has a first groove and a second groove that correspond to the positions of the first lower cavity and the second lower cavity respectively and allow gas to pass through.

[0013] In summary, the beneficial effects of the above-described technical solutions conceived by this utility model compared with the prior art include:

[0014] This invention relates to a multi-stage Roots vacuum pump exhaust structure. It comprises a first upper chamber and a second upper chamber, each with an independent return and exhaust port, on a working plate, combined with a lower chamber channel below them, forming a graded pressure-response exhaust path. When the gas reaches a certain pressure, it opens the first valve core through the first inlet of the two-stage rotor, and the gas is discharged after two stages of compression. When the pressure is normal, the gas is compressed by each stage of rotors and passes through the second inlet, opening the second valve core for normal exhaust. The main channel on the lower surface of the working plate converges the exhaust ports of each stage and discharges them uniformly from the main outlet on the side wall, simplifying external pipeline connections. The mating structure of the ball valve core and the inner conical guide seat ensures smooth opening and closing of the valve core under pressure and forms an effective seal upon retraction, preventing gas backflow. The removable sealing plate facilitates maintenance of the upper chamber interior and valve core. The groove on the cover plate corresponding to the lower chamber provides a smooth gas flow channel, reducing pressure loss. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the location of the exhaust structure of the multi-stage Roots vacuum pump of this utility model;

[0016] Figure 2 This is a schematic diagram of the top surface of the exhaust structure of the multi-stage Roots vacuum pump of this utility model;

[0017] Figure 3 This is a schematic diagram of the top surface structure of the working board of this utility model;

[0018] Figure 4 This is a schematic diagram of the bottom structure of the working board of this utility model;

[0019] Figure 5 This is a schematic cross-sectional view of the exhaust structure of the multi-stage Roots vacuum pump of this utility model;

[0020] Figure 6 This is a schematic diagram of the top surface structure of the cover plate of this utility model.

[0021] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically:

[0022] Exhaust assembly 1; Vacuum pump body 2; Working plate 11; Cover plate 12; Sealing plate 111

[0023] Main channel 112; Main outlet 1121; First upper cavity 113; First air inlet 1131; First lower cavity 1132;

[0024] First return air port 1133; First air outlet 1134; First valve core 1135; First guide seat 1136; Second upper cavity 114;

[0025] Second air inlet 1141; Second lower cavity 1142; Second air return port 1143; Second air outlet 1144; Second valve core 1145;

[0026] Second guide seat 1146; first groove 121; second groove 122. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0029] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0030] In the embodiments, by Figure 1-6 Provided is a multi-stage Roots vacuum pump exhaust structure, including a vacuum pump body 2 and an exhaust assembly 1 disposed at the bottom of the vacuum pump body 2. The exhaust assembly 1 includes a working plate 11 and a cover plate 12 disposed at its bottom. The upper surface of the working plate 11 has a first upper cavity 113 and a second upper cavity 114. The bottom surface of the first upper cavity 113 is provided with an independent first return port 1133 and a first outlet port 1134. The bottom surface of the second upper cavity 114 is provided with an independent second return port 1143 and a second outlet port 1144. 144; A first air inlet 1131 is provided through the side of the first upper cavity 113, and a second air inlet 1141 is provided through the side of the second upper cavity 114. The lower surface of the exhaust assembly 1 has a first lower cavity 1132 that connects the first air inlet 1131 and the first return air port 1133, and a second lower cavity 1142 that connects the second air inlet 1141 and the second return air port 1143. A first valve core 1135 is placed above the first return air port 1133, and a second valve core 1145 is placed above the second return air port 1143.

[0031] This structure, by setting up a first upper cavity 113 and a second upper cavity 114 on the working plate 11, and corresponding first return air port 1133, first outlet air port 1134, second return air port 1143, second outlet air port 1144, first inlet air port 1131, second inlet air port 1141, first lower cavity 1132 and second lower cavity 1142, and combining with the first valve core 1135 and the second valve core 1145, realizes the interstage venting function of the multi-stage Roots pump; when the gas pressure is too high, the valve core is pushed open, and the gas is directly discharged through the return air port and the outlet air port, avoiding pressure accumulation during the compression process, effectively preventing motor overload during the start-up phase, and improving motor stability and service life.

[0032] In a preferred embodiment of this utility model, the lower surface of the working plate 11 has a main channel 112 connecting the first air outlet 1134 and the second air outlet 1144, and the side wall of the working plate 11 has a main outlet 1121 connecting the main channel 112. By providing the main channel 112 on the lower surface of the working plate 11 and the main outlet 1121 on the side wall, the exhaust paths of the first air outlet 1134 and the second air outlet 1144 are converged, simplifying the exhaust system structure, reducing external connecting parts, improving exhaust efficiency, and making the overall layout more compact, facilitating installation and maintenance.

[0033] In a preferred embodiment of this utility model, a first guide seat 1136 is provided above the first return air port 1133, connecting to the first return air port 1133; a second guide seat 1146 is provided above the second return air port 1143, connecting to the second return air port 1143; a first valve core 1135 is placed in the first guide seat 1136; and a second valve core 1145 is placed in the second guide seat 1146. By providing the first guide seat 1136 above the first return air port 1133 and the second guide seat 1146 above the second return air port 1143, and placing the first valve core 1135 and the second valve core 1145 therein respectively, the guide seats provide precise guidance and limiting for the valve cores, ensuring stable movement of the valve cores under gas pressure, improving response speed and sealing reliability, and reducing the risk of valve core jamming or leakage.

[0034] As a preferred embodiment of this utility model, the first valve core 1135 and the second valve core 1145 are spherical in shape. The first valve core 1135 and the second valve core 1145 adopt a spherical shape, which has a simple structure and is easy to process. The spherical valve core rolls smoothly in the guide seat, has good sealing performance, can quickly respond to changes in gas pressure, realize efficient opening and closing, and reduce maintenance costs.

[0035] As a preferred embodiment of this utility model, the first guide seat 1136 and the second guide seat 1146 are shaped like inner conical surfaces. The first guide seat 1136 and the second guide seat 1146 adopt the shape of inner conical surfaces to form a conical sealing fit with the ball valve core. When the valve core is closed, the inner conical surface provides uniform contact pressure, enhances the sealing effect, prevents gas back leakage, and improves the accuracy and reliability of exhaust control.

[0036] As a preferred embodiment of this utility model, a sealing plate 111 is detachably provided on the top of the first upper cavity 113 and the second upper cavity 114. While ensuring the airtightness of the first upper cavity 113 and the second upper cavity 114, the sealing plate 111 also forms a block on the top of the first valve core 1135 and the second valve core 1145, preventing them from moving excessively and detaching from the valve seat.

[0037] In a preferred embodiment of this utility model, the upper surface of the cover plate 12 has a first groove 121 and a second groove 122 corresponding to the positions of the first lower cavity 1132 and the second lower cavity 1142, respectively, for gas passage. The first groove 121 and the second groove 122 on the upper surface of the cover plate 12, corresponding to the first lower cavity 1132 and the second lower cavity 1142, provide a smooth channel for gas flow, reduce airflow resistance, avoid local pressure loss, improve gas transmission efficiency, and ensure stable interstage exhaust.

[0038] Working principle: After the gas is discharged from the vacuum pump body 2, it enters through the second air inlet 1141 on the upper surface of the working plate 11, flows through the second lower cavity 1142 on the lower surface of the exhaust assembly 1, and reaches the second return air port 1143; when the gas pressure reaches the set value, it pushes the second valve core 1145 to move upward, and the gas then enters the second upper cavity 114 through the second return air port 1143, and is then discharged through the second air outlet 1144 into the main channel 112 on the lower surface of the working plate 11; the main channel 112 receives gas from the first air outlet 1134 and the second upper cavity 1144. After the gas from the two outlets 1144 is collected, it is discharged uniformly from the total outlet 1121 on the side wall of the working plate 11. When the system pressure increases further, the first-stage exhaust system is started simultaneously. The gas enters from the first inlet 1131, passes through the first lower cavity 1132 to the first return port 1133, opens the first valve core 1135 and enters the first upper cavity 113, and then flows into the total channel 112 through the first outlet 1134 for discharge. This structure effectively avoids motor overload during pump start-up and high-pressure operation through dual-stage pressure response exhaust, ensuring stable operation.

[0039] In summary, this utility model's multi-stage Roots vacuum pump exhaust structure, by setting a first upper chamber and a second upper chamber with independent return and exhaust ports on the working plate, combined with the lower chamber channel below them, forms a graded pressure-response exhaust path. When the gas reaches a certain pressure, it will open the first valve core through the first inlet of the two-stage rotor, and the gas will be discharged after two stages of compression. When the pressure is normal, the gas will be compressed by each stage rotor and pass through the second inlet, opening the second valve core for normal exhaust. The main channel on the lower surface of the working plate merges the exhaust ports of each stage and discharges them uniformly from the main outlet on the side wall, simplifying the external pipeline connection. The mating structure of the ball valve core and the inner conical guide seat ensures that the valve core can open and close smoothly under air pressure and forms an effective seal when it falls back, preventing gas backflow. The removable sealing plate facilitates maintenance of the upper chamber and valve core. The groove on the cover plate corresponding to the lower chamber provides a smooth channel for gas flow and reduces pressure loss.

[0040] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-stage Roots vacuum pump exhaust structure, comprising a vacuum pump body (2) and an exhaust assembly (1) disposed at the bottom of the vacuum pump body (2), the exhaust assembly (1) comprising a working plate (11) and a cover plate (12) disposed at its bottom, characterized in that: The upper surface of the working plate (11) has a first upper cavity (113) and a second upper cavity (114). The bottom surface of the first upper cavity (113) is provided with its own independent first return air port (1133) and first air outlet (1134). The bottom surface of the second upper cavity (114) is provided with its own independent second return air port (1143) and second air outlet (1144). A first air inlet (1131) is provided through the side of the first upper cavity (113), and a second air inlet (1141) is provided through the side of the second upper cavity (114). The lower surface of the exhaust assembly (1) has a first lower cavity (1132) that connects the first air inlet (1131) and the first air return port (1133), and a second lower cavity (1142) that connects the second air inlet (1141) and the second air return port (1143). A first valve core (1135) is placed above the first return air port (1133), and a second valve core (1145) is placed above the second return air port (1143).

2. The exhaust structure according to claim 1, characterized in that, The lower surface of the working plate (11) has a main channel (112) connecting the first air outlet (1134) and the second air outlet (1144), and the side wall of the working plate (11) has a main outlet (1121) connecting the main channel (112).

3. The exhaust structure according to claim 1, characterized in that, A first guide seat (1136) is provided above the first return air port (1133) to connect to the first return air port (1133), and a second guide seat (1146) is provided above the second return air port (1143) to connect to the second return air port (1143). The first valve core (1135) is placed in the first guide seat (1136), and the second valve core (1145) is placed in the second guide seat (1146).

4. The exhaust structure according to claim 3, characterized in that, The first valve core (1135) and the second valve core (1145) are spherical in shape.

5. The exhaust structure according to claim 4, characterized in that, The first guide seat (1136) and the second guide seat (1146) are in the shape of an inner conical surface.

6. The exhaust structure according to claim 1, characterized in that, The top of the first upper cavity (113) and the second upper cavity (114) are detachably equipped with sealing plates (111).

7. The exhaust structure according to claim 1, characterized in that, The upper surface of the cover plate (12) has a first groove (121) and a second groove (122) that correspond to the positions of the first lower cavity (1132) and the second lower cavity (1142) respectively and allow gas to pass through.

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