Air-cooled screw vacuum pump

Abstract

The application provides an air-cooled screw vacuum pump, which is provided with an end cover and a front cover at the front end of a pump body, the front cover is arranged at the front end of the end cover, the inner cavity of the pump body is provided with driving and driven shafts in parallel, the driving and driven shafts are respectively provided with driving and driven rotors, the driving and driven rotors are provided with helical grooves with opposite directions, and the driving and driven rotors are synchronously engaged and rotated; the front end of the front cover is provided with a motor, the front end of the driving shaft is coaxially connected with the motor through the front cover; the front ends of the driving and driven shafts are engaged through gears; the inner side of the rear end of the rotor is provided with a helical groove, the helical grooves on the inner and outer sides of the rotor are in the same direction, the rear end of the shaft is provided with a helical sleeve corresponding to the helical groove, the helical direction of the helical sleeve on the same shaft is opposite to the helical direction of the rotor, an isolation sleeve is arranged between the helical sleeve and the rotor, and the rear end of the pump body is provided with a cooling and purging air inlet communicated with the helical groove. The application can improve the back pressure capacity of the cooling and purging airflow and the heat exchange efficiency of the rotor and the airflow, and has good cooling effect.

Description

Technical Field

[0001] This invention belongs to the field of vacuum pump technology and relates to an air-cooled screw vacuum pump. Background Technology

[0002] A twin-screw vacuum pump is a pumping device that utilizes two screws rotating synchronously and at high speed in opposite directions within the pump body to generate suction and exhaust. It is a replacement for oil-sealed vacuum pumps and can pump gases containing large amounts of water vapor and small amounts of dust. It is widely used in major pharmaceutical and chemical companies in China. To ensure that the components inside the pump casing do not overheat after prolonged operation, a cooling structure is generally installed in the screw vacuum pump. This cooling structure exchanges heat between the screw vacuum pump and the external environment, displacing the heat generated during operation and thus preventing high temperatures from affecting the pump's performance.

[0003] For example, the corrosion-resistant screw vacuum pump disclosed in Chinese Patent (Authorization Announcement No.: CN217080785U) includes a shell and a bushing. The bushing is made of a corrosion-resistant metal material, the shell is integrally cast, and the bushing is transversely inserted into the shell. The shell and bushing are fixedly connected by welding, forming a cooling chamber between them. In the aforementioned prior art, the coolant in the cooling chamber absorbs the heat transferred to the outer wall of the bushing, thereby achieving the purpose of cooling the screw vacuum pump. However, ordinary screw vacuum pumps must withstand a pressure difference of one atmosphere during operation, and the last stage of the exhaust section bears about 90% of this pressure difference, with 90% of the pump's heat generation originating from here. The solution described in the aforementioned prior art cannot provide targeted cooling for the rotor's exhaust section, thus failing to achieve a satisfactory cooling effect. Summary of the Invention

[0004] The purpose of this invention is to provide an air-cooled screw vacuum pump to solve the problems mentioned in the background art.

[0005] The objective of this invention can be achieved through the following technical solution: A wind-cooled screw vacuum pump, characterized in that it includes a pump body, with an end cover and a front cover at its front end. The front cover is located at the front end of the end cover. A drive shaft and a driven shaft are arranged parallel to each other inside the pump body. A drive and a driven helical rotor are sleeved on the shaft. The outer sides of the drive and driven helical rotors are provided with helical grooves in opposite directions, and the drive and driven helical rotors mesh and rotate synchronously. A front bearing corresponding to the front end of the shaft is provided inside the end cover, and a rear bearing corresponding to the rear end of the shaft is provided at the rear of the pump body. A motor is located at the front end of the front cover, and the front end of the drive shaft passes through the front cover. It is coaxially connected to the motor; the front cover has two meshing synchronous gears, which are respectively sleeved on the front ends of the main and driven shafts; the inner side of the rear end of the rotor has a helical groove, and the helical grooves on the inner and outer sides of the rotor are in the same direction; the rear end of the rotor shaft is fitted with a helical sleeve at the helical groove, and the helical direction of the helical sleeve on the same shaft is opposite to that of the rotor. An isolation sleeve is provided between the helical sleeve and the inner helical groove of the rotor. The helical groove of the helical sleeve is connected to the end of the inner helical groove of the rotor near the front end of the pump body. The rear end of the pump body has a cooling purge air inlet that communicates with the helical groove of the helical sleeve.

[0006] The working principle of this invention is as follows: A separating sleeve separates the spiral sleeve and the inner spiral groove of the rotor, forming two spiral airflow channels connected at both ends. During normal operation, the gas inside the separating sleeve flows into the rotor under the rotation of the spiral sleeve and is drawn in through the cooling purge inlet; the gas outside the separating sleeve flows towards the rotor end under the rotation of the inner spiral groove. The rotation of the spiral groove promotes heat exchange between the inner and outer sides of the cooling gas and increases the contact strength between the spiral groove side and the cooling gas. Simultaneously, the spiral groove increases the contact area between the rotor and the cooling gas. This structure improves the heat exchange effect between the cooling gas and the rotor during flow, allowing for direct and efficient cooling of the rotor.

[0007] In the aforementioned air-cooled screw vacuum pump, the inner and outer spiral grooves of the driving rotor have the same spiral direction, as do the inner and outer spiral grooves of the driven rotor; the spiral direction of the spiral sleeve is opposite to that of the spiral groove on the inner side of its corresponding rotor. Separated by the isolation sleeve, the high-speed rotation of the inner and outer opposite spiral structures causes the airflow to flow in opposite directions. Connected at the ends, they form a relay pattern, increasing the power of the purging airflow. While ensuring the flow rate and velocity of the cooling purging airflow, this enhances the cooling purging airflow's resistance to exhaust back pressure, ensuring the effectiveness of the cooling purging process.

[0008] In the aforementioned air-cooled screw vacuum pump, a plurality of heat dissipation fins are uniformly arranged along the axial direction of the pump body. Adjacent heat dissipation fins form an airflow channel that runs directly from the rear end face of the pump body to the flange at the front end face of the pump body. There are no radial heat dissipation fins, preventing airflow redirection within the outer airflow channel of the pump body. This increases the distance the axial airflow generated by the axial flow fan travels close to the pump body surface, improving the cooling effect on the pump body surface. A fan is also installed at the rear end of the pump body, and a fan housing is provided around the fan. The fan housing is bolted to the rear end of the pump body. The inner cavity of the fan housing is connected to the airflow channel. The inner wall of the fan housing is tightly attached to the outer surface of the heat dissipation fins at the rear end of the pump body, ensuring that all axial airflow generated by the axial flow fan can only exit through the outer airflow channel of the pump body, improving the fit between the airflow and the outer surface shape of the pump body. A plurality of air inlets are provided at the end of the fan housing corresponding to the range of motion of the fan blades.

[0009] In the aforementioned air-cooled screw vacuum pump, a flow-limiting plate is provided inside the fan housing, located on the outer periphery of the fan. The flow-limiting plate restricts the radial airflow range of the axial fan, preventing gas inside the plate from radially escaping outwards and converting it entirely into axial airflow, thereby enhancing the intensity of the axial airflow generated by the axial fan. The flow-limiting plate also prevents the axial airflow generated by the fan from flowing back to the fan's working area from both sides, avoiding losses caused by ineffective airflow and improving the actual efficiency of the axial fan.

[0010] In the aforementioned air-cooled screw vacuum pump, the rear end face of the pump body is recessed to form a step, and the rear bearing is installed in the step. A cover plate is bolted to the rear end face of the pump body. The outer edge of the cover plate is flush with the root of the heat dissipation fins.

[0011] In the aforementioned air-cooled screw vacuum pump, both the rear ends of the driving rotor and the driven rotor are pressure-bearing sections, which are divided into n stages, with the outer diameter of each pressure-bearing section decreasing progressively from front to back.

[0012] In the aforementioned air-cooled screw vacuum pump, the front end of the pump body is provided with an air inlet and the rear end is provided with an air outlet, both of which are connected to the inner cavity of the pump body.

[0013] In the aforementioned air-cooled screw vacuum pump, the cooling purge inlet adopts a countersunk thread structure and is connected to an external straight pipe to avoid local enlargement at the connection point affecting the flow of cooling air in the airflow channel between the heat dissipation fins on the outside of the pump body.

[0014] In the aforementioned air-cooled screw vacuum pump, the pump body has an outer flange at its front end, and the end cover is connected to the outer flange by screws.

[0015] Compared with the prior art, the advantages of this invention are as follows: By setting an end face flange at the front end of the pump body and a bearing seat mounting plate at the rear end of the pump body, the two ends can act as circumferential reinforcing ribs, and combined with the outer axial reinforcing ribs, the structural strength of the pump body is ensured; by setting axial heat dissipation ribs that run straight from the rear end face to the front flange on the outside of the pump body, without radial heat dissipation ribs, the airflow in the airflow channel on the outside of the pump body is prevented from changing direction and shape, increasing the distance that the axial airflow generated by the axial fan flows close to the outer surface of the pump body, thus improving the air cooling effect of the outer surface of the pump body; through the structural design of the fan casing, the intensity of the effective axial airflow generated by the axial flow fan is improved, as well as the fit between the airflow and the shape of the outer surface of the pump body, thereby further improving the air cooling effect of the outer surface of the pump body; by setting a spiral groove on the inner side of the rotor, the contact area between the rotor and the airflow is increased, improving the cooling effect, and providing power, improving the ability of the cooling purge airflow to resist exhaust back pressure, ensuring the flow rate and velocity of the cooling purge airflow, and utilizing the phenomenon of the high-speed rotating spiral surface forcing the cooling purge airflow forward, the contact strength between the cooling purge airflow and the rotor surface is improved, ensuring the connection between the cooling purge airflow and the rotor surface. The heat exchange efficiency of the contact surface is improved; thirdly, the cooling purging airflow is forced to exchange heat between the inside and outside, ensuring the temperature difference between the rotor surface and the airflow surface at the contact point, further improving the heat exchange efficiency of the contact surface; fourthly, by introducing external gas to purge, the flow rate of the gas discharged from the pump exhaust port is increased, thereby allowing more heat to be directly carried away by the high-temperature exhaust airflow, reducing the requirements on the pump cooling system; by adding n-stage pressure-bearing sections at the rotor end for pressure distribution, and the outer diameter of the pressure-bearing sections adopts a stepped structure, by adjusting the gap between the rotor and the pump body, a stable pressure is formed between the outer circle of the rotor and the pump cavity. A fixed reflux gas channel reduces the pressure difference between adjacent stages in the rotor's pressure-bearing section by allowing gas reflux, thus distributing the pressure difference originally borne by the last stage to the n+1 stages for joint bearing, while keeping the pump's power consumption unchanged. Theoretically, this can reduce the heat generation per unit space in the high-temperature zone of the pump chamber to 1 / (n+1), significantly reducing the cooling demand per unit area in the high-temperature zone of the pump body. Furthermore, due to the influence of the high-temperature reflux gas, the inner surface of the pump body in the pressure-bearing section is in constant contact with the high-temperature gas, and the effective cooling area of ​​the inner surface of the pump body in this area reaches 100%, which significantly increases the effective cooling area under the same conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the air-cooled screw vacuum pump of the present invention.

[0017] Figure 2 This is a cross-sectional schematic diagram of the air-cooled screw vacuum pump of the present invention from one direction.

[0018] Figure 3 This is a cross-sectional schematic diagram of the air-cooled screw vacuum pump of the present invention from another direction.

[0019] Figure 4This is a schematic diagram of the pump body structure of the air-cooled screw vacuum pump of the present invention.

[0020] Figure 5 This is a schematic diagram of the rotor structure of the air-cooled screw vacuum pump of the present invention.

[0021] Figure 6 This is a schematic diagram of the fan housing structure of the air-cooled screw vacuum pump of the present invention.

[0022] In the diagram, 1. Pump body; 1a. Outer flange; 1b. Air inlet; 1c. Air outlet; 1d. Cooling purge air inlet; 1e. Heat dissipation fins; 1f. Step; 2. End cover; 3. Front cover; 41. Drive shaft; 42. Driven shaft; 51. Driven rotor; 52. Driven rotor; 5a. Pressure bearing section; 6. Front bearing; 7. Rear bearing; 8. Motor; 9. Gear; 10. Spiral groove; 11. Spiral sleeve; 12. Isolation sleeve; 13. Airflow channel; 14. Fan; 15. Fan housing; 15a. Air inlet; 15b. Flow restrictor; 16. Cover plate. Detailed Implementation

[0023] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0024] like Figures 1-3As shown, an air-cooled screw vacuum pump includes a pump body 1 and an end cover 2. The pump body 1 has an outer flange 1a at its front end, and the end cover 2 is connected to the outer flange 1a by screws. A front cover 3 is provided at the front end of the end cover 2. The pump body 1 has an air inlet 1b at its front end and an air outlet 1c at its rear end, both of which communicate with the inner cavity of the pump body 1. A drive shaft 41 and a driven shaft 42 are arranged parallel to each other within the inner cavity of the pump body 1. A drive rotor 51 and a driven rotor 52 are fitted onto the shaft 41. The outer sides of the drive rotor 51 and the driven rotor 52 have helical grooves in opposite directions, allowing the drive rotor 51 and the driven rotor 52 to rotate synchronously in opposite directions. A front bearing 6 corresponding to the front ends of the drive shaft 41 and the driven shaft 42 is provided inside the end cover 2, and a rear bearing 7 corresponding to the rear ends of the drive shaft 41 and the driven shaft 42 is provided at the rear of the pump body 1. A motor 8 is located at the front end of the front cover 3, and the drive shaft... The front end of shaft 41 passes through the front cover 3 and is coaxially connected to the motor 8. Two meshing synchronous gears 9 are provided inside the front cover 3, respectively fitted onto the front ends of the drive shaft 41 and driven shaft 42. Spiral grooves 10 are provided on the inner sides of the rear ends of both the drive rotor 51 and driven rotor 52. The spiral directions of the spiral grooves on the inner and outer sides of the drive rotor 51 and driven rotor 52 are the same. Spiral sleeves 11 are fitted onto the rear ends of the drive shaft 41 and driven shaft 42 corresponding to the spiral grooves 10. Taking the drive shaft 41 as an example, the spiral direction of the spiral sleeve 11 on the drive shaft 41 is opposite to that of the drive rotor 51. An isolation sleeve 12 is provided between the spiral sleeve 11 and the spiral groove 10 on the inner side of the drive rotor 51. A cooling purge inlet 1d communicating with the spiral sleeve 11 is provided at the rear end of the pump body 1. In this embodiment, the cooling purge inlet 1d adopts a countersunk thread structure, and the cooling purge inlet pipe is connected to the countersunk thread using a straight pipe thread.

[0025] See Figure 3 and Figure 6The pump body 1 has several cooling fins 1e along its axial direction on its outer periphery. Adjacent cooling fins 1e form an airflow channel 13 that runs directly from the rear end face of the pump body 1 to the flange on the front end face of the pump body 1. There are no radial cooling fins, which prevents the airflow within the airflow channel 13 on the outer side of the pump body 1 from changing direction or shape. This increases the distance the axial airflow generated by the axial fan 14 travels close to the surface of the pump body 1, improving the air cooling effect on the outer surface of the pump body 1. A fan 14 is also installed at the rear end of the pump body 1. The fan 14 is covered by a fan housing 15. 5. The fan housing 15 is fixed to the rear end of the pump body 1 with bolts. The inner cavity of the fan housing 15 is connected to the airflow channel 13. The inner wall of the fan housing 15 is in close contact with the outer surface of the heat dissipation fin 1e at the rear end of the pump body 1, so that the axial airflow generated by the axial flow fan 14 can only be discharged through the outer airflow channel of the pump body 1, which improves the fit between the airflow and the shape of the outer surface of the pump body 1, thereby further improving the air cooling effect of the outer surface of the pump body 1. Several air inlet holes 15a are opened at the end of the fan housing 15 corresponding to the movement range of the fan blades 14. A flow limiting plate 15b is provided in the inner cavity of the fan housing 15, and the flow limiting plate 15b is located on the outer periphery of the fan 14. The radial airflow range of the axial fan 14 is limited to prevent the gas inside the flow restrictor 15b from escaping radially outward, so that it is completely converted into axial airflow, thereby enhancing the intensity of the axial airflow generated by the axial fan 14. The bottom of the flow restrictor 15b is connected to the end face of the fan casing 15 without gaps, blocking the gas on both sides from flowing back to the working area of ​​the fan 14, thus avoiding the loss of ineffective airflow.

[0026] like Figure 4 As shown, the rear end face of the pump body 1 is recessed to form a step 1f, and the rear bearing 7 is installed in the step 1f. A cover plate 16 is bolted to the rear end face of the pump body 1, and the outer edge of the cover plate 16 is flush with the root of the heat dissipation fin 1e. Through this structural design, the outer flange structure at the rear end of the pump body 1 is eliminated, and the radial dimension of the cover plate 16 is reduced, so that the airflow channel 13 between the heat dissipation fins 1e is directly inside the fan housing 15. This avoids the cooling airflow generated by the fan 14 from being redirected or causing pressure loss due to the obstruction of the cover plate 16, and ensures the flow rate, velocity and action area of ​​the cooling airflow close to the outer surface of the pump body 1. At the same time, the recessed step 1f structure can act as a circumferential reinforcing rib, avoiding the risk of weakened structural strength caused by the lack of circumferential reinforcing ribs on the outer side of the exhaust end of the pump body 1.

[0027] like Figure 5 As shown, both the driving rotor 51 and the driven rotor 52 have pressure-bearing sections 5a at their rear ends. These pressure-bearing sections 5a are divided into n stages, with the outer diameter of each stage decreasing progressively from front to back. In this embodiment, the pressure-bearing sections 5a are divided into three stages, each with a length of L. The corresponding outer diameters for each stage are D1, D2, and D3, respectively. The outer diameter of the rotor 5 is D, where D > D1 > D2 > D3. This design disperses the pressure difference of the last stage through a stepped 1f structure, reducing the cooling requirement per unit area of ​​the pump body 1 and increasing the effective cooling area of ​​the pump body 1's inner surface.

[0028] This invention utilizes a structure including an outer flange 1a at the front end of the pump body 1 and a bearing seat mounting plate at the rear end of the pump body 1. These structures act as circumferential reinforcing ribs at both ends, and, combined with axial reinforcing ribs on the outer side, ensure the structural strength of the pump body 1. By providing an axial cooling rib 1e extending from the rear end face directly to the front outer flange 1a on the outer side of the pump body 1, without other radial cooling ribs, the airflow in the outer airflow channel of the pump body 1 is prevented from changing direction or shape, increasing the distance the axial airflow generated by the fan 14 travels close to the outer surface of the pump body 1, thus improving the air-cooling effect on the outer surface of the pump body 1. Furthermore, the structural design of the fan casing 15 enhances the intensity of the effective axial airflow generated by the fan 14 and improves the fit between the airflow and the shape of the outer surface of the pump body 1, thereby further improving the air-cooling effect on the outer surface of the pump body 1. The rear ends of the active rotor 51 and the driven rotor 52 are designed as multi-stage pressure-bearing sections 5a with gradually decreasing outer diameters, which disperses the pressure difference at the rear ends of the rotors and reduces the cooling requirements. At the same time, two spiral airflow channels with connected ends are formed within the active rotor 51 and the driven rotor 52, which can generate a stable cooling purge airflow to directly and efficiently cool the active rotor 51 and the driven rotor 52, greatly improving the cooling effect. Utilizing the working principle of the spiral groove 10, the temperature difference between the cooling purge airflow and the rotor contact surface is ensured by promoting heat exchange between the inner and outer sides of the cooling purge airflow. By increasing the contact strength between the rotor surface and the cooling purge airflow, the heat exchange efficiency is improved, thereby improving the cooling effect. At the same time, the cooling purge airflow removes more heat from the pump chamber, directly reducing the pump's requirements for the cooling system.

[0029] Contents not described in detail herein are existing technologies known to those skilled in the art. The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. An air-cooled screw vacuum pump, characterized in that, The pump body (1) includes an end cover (2) and a front cover (3) at its front end. The front cover (3) is located at the front end of the end cover (2). A drive shaft (41) and a driven shaft (42) are arranged parallel to each other in the inner cavity of the pump body (1). The drive shaft (41) is fitted with a drive rotor (51), and the driven shaft (42) is fitted with a driven rotor (52). The drive rotor (51) and the driven rotor (52) rotate synchronously in opposite directions. A front bearing (6) corresponding to the front end of the drive shaft (41) and the driven shaft (42) is provided inside the end cover (2). A rear bearing (7) corresponding to the rear end of the drive shaft (41) and the driven shaft (42) is provided at the rear end of the pump body (1). A motor (8) is provided at the front end of the front cover (3), wherein the front end of the drive shaft (41) passes through the front cover (3) and is coaxially connected to the motor (8). A meshing mechanism is provided inside the front cover (3). Two synchronous gears (9) are fitted together, and the two gears (9) are respectively fitted on the front end of the drive shaft (41) and the driven shaft (42); the drive rotor (51) and the driven rotor (52) are provided with spiral grooves (10) on the outer side and the inner side of the rear end, and the spiral direction of the spiral grooves (10) on the inner and outer sides of the drive rotor (51) is the same; the spiral direction of the spiral grooves (10) on the inner and outer sides of the driven rotor (52) is the same; the rear end of the drive shaft (41) and the driven shaft (42) is fitted with a spiral sleeve (11) corresponding to the spiral groove (10), and the spiral direction of the spiral sleeve (11) is opposite to the spiral direction of the spiral groove (10) of the corresponding rotor. An isolation sleeve (12) is provided between the spiral sleeve (11) and the spiral groove (10) on the inner side of the corresponding rotor. The rear end of the pump body (1) is provided with a cooling purge air inlet (1d) communicating with the spiral sleeve (11).

2. The air-cooled screw vacuum pump according to claim 1, characterized in that, The spiral directions of the inner and outer spiral grooves (10) of the active rotor (51) are the same; the spiral directions of the inner and outer spiral grooves (10) of the driven rotor (52) are the same; the spiral direction of the spiral sleeve (11) is opposite to the spiral direction of the spiral groove (10) on the inner side of the driven rotor.

3. A wind-cooled screw vacuum pump according to claim 1 or 2, characterized in that, The pump body (1) has a number of heat dissipation ribs (1e) evenly arranged along its axial direction on the outer periphery. An airflow channel (13) is formed between adjacent heat dissipation ribs (1e) from the rear end face of the pump body (1) to the flange of the front end face of the pump body (1). A fan (14) is also installed at the rear end of the pump body (1). The fan (14) is covered with a fan cover (15). The fan cover (15) is fixed to the rear end of the pump body (1) by bolts. The inner wall of the fan cover (15) is close to the outer surface of the heat dissipation ribs (1e) at the rear end of the pump body (1). The inner cavity of the fan cover (15) is connected to the airflow channel (13). A number of air inlets (15a) are opened at the end of the fan cover (15) corresponding to the range of motion of the fan (14) blades.

4. The air-cooled screw vacuum pump according to claim 3, characterized in that, The inner cavity of the fan housing (15) is provided with a flow limiting plate (15b), which is located on the outer periphery of the fan (14).

5. A wind-cooled screw vacuum pump according to claim 1 or 2, characterized in that, The rear end face of the pump body (1) is recessed to form a step (1f), and the rear bearing (7) is installed in the step (1f). The rear end face of the pump body (1) is connected to a cover plate (16) by bolts, and the outer edge of the cover plate (16) is flush with the root of the heat dissipation fin (1e).

6. A wind-cooled screw vacuum pump according to claim 1 or 2, characterized in that, The rear ends of both the active rotor (51) and the driven rotor (52) are pressure-bearing sections (5a). The pressure-bearing sections (5a) are divided into n levels. The outer diameter of the pressure-bearing sections (5a) is smaller than the outer diameter of the front ends of the active rotor (51) and the driven rotor (52), and decreases gradually from front to back.

7. A wind-cooled screw vacuum pump according to claim 1 or 2, characterized in that, The pump body (1) has an air inlet (1b) at the front end and an air outlet (1c) at the rear end. Both the air inlet (1b) and the air outlet (1c) are connected to the inner cavity of the pump body (1).

8. A wind-cooled screw vacuum pump according to claim 1 or 2, characterized in that, The cooling purge air inlet (1d) adopts a countersunk thread structure and is connected to an external straight pipe.

9. A wind-cooled screw vacuum pump according to claim 1 or 2, characterized in that, The pump body (1) has an outer flange (1a) at the front end, and the end cover (2) is connected to the outer flange (1a) by screws.

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