Strong self-suction high-pressure external double-suction double-screw pump

Abstract

The invention discloses a strong self-suction high-pressure external double-suction double-screw pump which comprises a pump body, a screw pair is arranged in the pump body, the screw pair comprises a driving screw and a driven screw, each of the two screws comprises a rotating shaft, a left helical casing and a right helical casing, the left helical casing and the right helical casing are fixedly arranged on the periphery of the rotating shaft, and the rotating shafts, the left helical casing and the right helical casing are made into a whole; the left spiral sleeve and the right spiral sleeve on each screw are provided with tooth-shaped grooves with the same shape, the thread turning directions of the left spiral sleeve and the right spiral sleeve are opposite, and the surfaces of the tooth-shaped grooves are covered with wear-resistant rubber layers; and the left helical casing and the right helical casing on the driving screw are correspondingly meshed and paired with the right helical casing and the left helical casing on the driven screw. The screw rod pair adopts an integrated design, so that the structural rigidity is enhanced, and the pump can bear higher working pressure; meanwhile, the tooth-shaped groove of the spiral sleeve is covered with the wear-resistant rubber layer, so that fine control over the meshing clearance of the screw is achieved, medium backflow is greatly reduced, and the self-suction efficiency and the volume efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of material conveying pump technology, specifically a strong self-priming high-pressure external double-suction twin-screw pump. Background Technology

[0002] External double-suction twin-screw pumps are widely used in various industries such as petroleum, chemical, metallurgy, steel, power, shipbuilding, pharmaceutical, food, and building materials. The variety of applicable media, the wide range of conveying, and the complexity of application conditions are unmatched by other pump products. These characteristics also make this series of pumps have potential for development.

[0003] Twin-screw pumps can be divided into two types: those with internal bearings and those with external bearings. In the internal bearing type, the bearing is lubricated by the conveyed material; in the external bearing type, the working chamber of the twin-screw pump is separate from the bearing. For an external double-suction twin-screw pump, the medium enters from the pump inlet and then enters the threaded meshing space from both ends of the screw sleeve. The liquid is pumped by the two meshing screws. The drive screw, which extends out of the pump, is driven by a prime mover. The drive screw and the driven screw have threads with different directions of rotation. The screw fits tightly against the pump body. The driven screw is driven by the drive screw through a synchronous gear, forming a screw pair.

[0004] Currently, most twin-screw pumps on the market cannot withstand high pressure, primarily due to insufficient rigidity of the screw assembly. Structurally, this is mainly caused by unreasonable design, including excessively wide connecting plates and excessively deep threads. As a positive displacement pump, a twin-screw pump should theoretically have its suction and discharge chambers tightly separated. Therefore, the clearance between the pump body and the outer surface of the screws, as well as between the screws themselves, should be as small as possible. Simultaneously, the screws and pump body, and between the screws themselves, should form sealed cavities to ensure airtightness; otherwise, liquid may flow back through the gaps. However, because the thread-to-thread meshing clearance is limited, too small a clearance can cause seizing or even jamming during pump operation, rendering the pump inoperable. Conversely, too large a clearance directly affects the pump's self-priming performance. Therefore, minimizing the screw thread clearance is a problem that urgently needs to be solved by existing technology. To address this, we provide a high-pressure, self-priming, externally mounted twin-screw pump with dual suction. Summary of the Invention

[0005] The purpose of this invention is to provide a strong self-priming high-pressure external double-suction twin-screw pump to solve the problems of difficult control of screw thread meshing clearance and insufficient rigidity of screw pair in the prior art.

[0006] This invention can be achieved through the following technical solution: a strong self-priming high-pressure external double-suction twin-screw pump, including a pump body, a set of screw pairs is provided in the pump body, the screw pairs include a driving screw and a driven screw, both of the screws include a rotating shaft and a left helical sleeve and a right helical sleeve fixed on their outer periphery, the three are made into a whole; The left and right helical sleeves on each screw have the same shaped toothed grooves, and the threads of the left and right helical sleeves are turned in opposite directions. The surface of the toothed grooves is covered with a wear-resistant rubber layer. The left and right helical sleeves on the driving screw mesh and pair with the right and left helical sleeves on the driven screw.

[0007] A further technical improvement of the present invention is that the tooth profile of the tooth groove includes a cycloid and an Archimedean spiral. The formation process of the cycloid includes: when rolling purely along the pitch circle of one spiral sleeve as the moving circle and the pitch circle of the other spiral sleeve as the fixed circle, the trajectory formed by a point on the outer circle corresponding to the moving circle is the cycloid point.

[0008] A further technical improvement of the present invention is that the wear-resistant rubber layer has a thickness of 0.1~2mm, and it is fixed to the toothed groove by hot vulcanization. The wear-resistant rubber layer is made of EPDM rubber.

[0009] A further technical improvement of the present invention is that the depth of the thread tooth profile of the toothed groove is set to 0.15 to 0.25 times the pitch circle of the spiral sleeve.

[0010] A further technical improvement of the present invention is that: the screw assembly is rotatably connected to the connecting plates fixed on both sides of the pump body through the bearing, and the two rotating shafts of the screw assembly are provided with sealing rings and are axially fixed by the sealing cover fixed to the inner side of the connecting plate. A double spring skeleton oil seal is provided on the side of the sealing cover away from the sealing ring. The double spring skeleton oil seal is located on the outer circumference of the rotating shaft, thereby forming a mechanical sealing cavity between the bearing and the corresponding screw sleeve.

[0011] A further technical improvement of the present invention is that: the connecting plate is provided with a vertical elongated hole and a transverse connecting hole at its bottom; the side wall of the sealing gland is provided with a through hole one and a through hole two that are perpendicularly connected to each other; the through hole one is connected to the mechanical seal cavity; and the two ends of the through hole two are respectively connected to the through hole one and the transverse connecting hole, thereby forming a flow channel structure that has both cooling and lubrication and high-pressure airflow purging functions.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The screw assembly in this invention adopts an integrated design, which enhances the structural rigidity and enables the pump to withstand higher working pressures. At the same time, in order to improve the high-pressure delivery performance of the pump, the pump structure is equipped with a combination of a sealing gland and a connecting plate, and the bearing is set on the connecting plate, which shortens the bearing spacing and makes the screw operation more stable and reliable. The thread depth is designed to be 0.15 to 0.25 times the pitch circle of the screw sleeve, ensuring sufficient rigidity, so it can withstand high pressure.

[0013] 2. The toothed groove of the spiral sleeve in this invention is covered with a wear-resistant rubber layer, which realizes the fine control of the screw meshing gap, greatly reduces the backflow of the medium, and improves the self-priming efficiency and volumetric efficiency; while in the prior art, the metal-to-metal mating gap can be 0.1-0.2mm, otherwise seizing will occur.

[0014] 3. The mechanical seal cavity design formed by the sealing ring, sealing gland and double spring skeleton oil seal of the present invention, together with the flow channel setting on the connecting plate, allows access to external cooling lubrication or high-pressure cleaning airflow, effectively reducing the temperature of the sealing cavity, reducing wear of the seal, and preventing media contamination. Attached Figure Description

[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic cross-sectional view of the overall structure of the present invention; Figure 2 This is a diagram showing the screw assembly of the present invention; Figure 3 This is a schematic diagram showing the opening state of the flow channel holes in the connecting plate structure of the present invention; Figure 4 This is a cross-sectional view of the sealing gland of the present invention; Figure 5 This is a cross-sectional view of the helical tooth groove of the screw pair of the present invention; Figure 6 This is a diagram showing the sealing tooth profile of the helical groove end section of the screw assembly of the present invention.

[0017] In the diagram: 1. Screw assembly; 2. Bearing; 3. Sealing ring; 4. Sealing gland; 5. Connecting plate; 6. Gear assembly; 7. Gearbox; 8. Pump body; 11. Drive shaft; 12. Drive left helical sleeve; 13. Drive right helical sleeve; 14. Driven right helical sleeve; 15. Driven left helical sleeve; 16. Driven shaft; 17. Wear-resistant rubber; 41. Through hole one; 42. Through hole two; 43. Double spring skeleton oil seal; 51. Mounting hole; 52. Vertical elongated hole; 53. Horizontal connecting hole; 54. Threaded hole. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0019] Please see Figure 1-4As shown, a high-pressure, self-priming, externally mounted double-suction twin-screw pump includes a pump body 8. Connecting plates 5 are symmetrically fixed on both sides of the pump body 8, and each connecting plate 5 has two mounting holes 51. A set of screw pairs 1 is installed inside the pump body 8. The screw pairs 1 include a driving screw and a driven screw. Both ends of the driving screw and the driven screw are rotatably mounted in the corresponding mounting holes 51 via bearings 2 mounted on their outer periphery. The driving screw includes a drive shaft 11, and a drive left helical sleeve 12 and a drive right helical sleeve 13 are provided on the outer periphery of the drive shaft 11. The three are configured as an integral component to ensure its rigidity and enable it to withstand high pressure. Similarly, the driven screw includes a driven shaft 16, and a driven right helical sleeve 14 and a driven left helical sleeve 15 are fixedly provided on the outer periphery of the driven shaft. The three are configured as an integral component. The drive left screw sleeve 12 and the driven right screw sleeve 14 have opposite thread directions and mesh with each other; the drive right screw sleeve 13 and the driven left screw sleeve 15 have opposite thread directions and mesh with each other. A gearbox 7 is fixedly installed on the outer side of one of the connecting plates 5. The drive shaft 11 of the active screw and the driven shaft 16 of the driven screw pass through the connecting plate 5 on this side, and the ends of the two are provided with a gear pair 6 that meshes with each other. The end of the drive shaft 11 away from the gearbox 7 passes through the connecting plate 5 on the other side and is fixedly connected to the output end of the power motor.

[0020] More specifically, on the inner side of each connecting plate 5, a sealing ring 3 is provided on the outer side of the drive shaft 11 and the driven shaft 16, and a sealing cap 4 is provided between the sealing ring 3 and the connecting plate 5 for axial limiting; a double spring skeleton oil seal 41 is provided on the side of the sealing cap 4 away from the sealing ring 3, thereby forming a mechanical seal cavity under the action of the sealing ring 3 and the double spring skeleton oil seal 41; vertical elongated holes 52 are symmetrically opened above and below the two mounting holes 51 of the connecting plate 5, and a transverse connecting hole 53 is opened at the bottom of the vertical elongated holes 52, and the top starting end surface of the vertical elongated holes 52 is set as a threaded hole 54; two sets of through holes one 41 and through holes two 42 are symmetrically opened on the side wall of the sealing cap 4, wherein through holes one 41 connects to the mechanical seal cavity, and the two ends of through holes two 42 connect through holes one 41 and transverse connecting holes 53 respectively; During use, the external cooling and lubrication system is connected through the threaded hole 54 on the connecting plate 5 to inject lubricating medium (such as lubricating oil) into the mechanical seal cavity and remove the generated heat, thereby improving the working environment of the mechanical seal. On the other hand, it can also be connected to the external high-pressure cleaning airflow to clean and blow away impurities generated in the mechanical seal cavity during long-term operation.

[0021] like Figure 5 As shown, the driving left screw sleeve 12, the driving right screw sleeve 13, the driven right screw sleeve 14 and the driven left screw sleeve 15 have the same tooth profile, and their tooth grooves are all composed of abcefg. Wherein, abc is a cycloid, efg is an Archimedean spiral, and ea is the bottom surface; the entire toothed groove is covered with a layer of wear-resistant rubber 17, and the thickness S of the rubber layer is 0.1~2mm; the wear-resistant rubber 17 and the toothed groove are fixed by hot vulcanization.

[0022] Preferably, the wear-resistant rubber is ethylene propylene diene monomer (EPDM) rubber, ensuring that it has good weather resistance, heat resistance, chemical resistance and excellent wear resistance, as well as good fit and firmness with the above-mentioned thread tooth shape.

[0023] The formation mechanism of the ABC cycloid in the toothed groove is as follows: Figure 6 As shown, when one spiral sleeve's pitch circle is the moving circle and the other spiral sleeve's pitch circle is the fixed circle, the outer circle of the moving circle forms the trajectory of the pendulum point. In this embodiment, the pitch circles of the left and right spiral sleeves are d and d', respectively, and both have the same diameter. The formation process of the sealing tooth shape abc of the right spiral sleeve's helical surface is as follows: when the left spiral sleeve's pitch circle d is the moving circle and the right spiral sleeve's pitch circle d' is the fixed circle, the outer circle a of the left spiral sleeve forms the trajectory of the pendulum point. Point c is the intersection of the cycloid and the outer circle of the right spiral sleeve.

[0024] More often, the depth of the thread tooth profile is set to 0.15 to 0.25 times the pitch circle of the helical sleeve.

[0025] During assembly, when the driving left helical sleeve 12 of the screw pair 1 meshes with the driven right helical sleeve 14, and the driving right helical sleeve 13 meshes with the driven left helical sleeve 15, the gap value can be 0.01-0.05mm, which greatly reduces the gap and significantly improves the self-priming performance. Driven by the motor, the screw assembly 1 rotates through the drive shaft 11 and the gear pair 6. The bearings 2 are arranged on both sides of the screw assembly 1 with a small gap. The mechanical seal cavity is set inside the bearings 2 to separate the transport medium from the lubrication and cooling medium. The structure is compact and has a strong pressure bearing capacity.

[0026] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-pressure, self-priming, externally mounted, double-suction, twin-screw pump, characterized in that: The pump body (8) includes a set of screw pairs (1) inside the pump body (8). The screw pairs (1) include a driving screw and a driven screw. Both screws include a rotating shaft and a left helical sleeve and a right helical sleeve fixed on their outer periphery. The three are made into a whole. The left and right helical sleeves on each screw have the same toothed grooves, and the threads of the left and right helical sleeves are opposite in direction. The surface of the toothed grooves is covered with a wear-resistant rubber layer (17). The left and right helical sleeves on the driving screw mesh and pair with the right and left helical sleeves on the driven screw.

2. The high-pressure, self-priming, externally mounted double-suction twin-screw pump according to claim 1, characterized in that, The tooth profile of the toothed groove includes a cycloid and an Archimedean spiral. The formation process of the cycloid includes: when rolling purely along the pitch circle of one spiral sleeve as the moving circle and the pitch circle of the other spiral sleeve as the fixed circle, the trajectory formed by a point on the outer circle corresponding to the moving circle is the cycloid point.

3. The high-pressure, self-priming, externally mounted double-suction twin-screw pump according to claim 1, characterized in that, The wear-resistant rubber layer (17) has a thickness of 0.1~2mm and is fixed to the toothed groove by hot vulcanization. The wear-resistant rubber layer is made of EPDM rubber.

4. The self-priming, high-pressure external double-suction twin-screw pump according to claim 1, characterized in that, The depth of the thread tooth profile of the toothed groove is set to 0.15 to 0.25 times the pitch circle of the helical sleeve.

5. A high-pressure, self-priming, externally mounted double-suction twin-screw pump according to claim 1, characterized in that, The screw assembly (1) is rotatably connected to the connecting plates (5) fixed on both sides of the pump body (8) via bearings. The two sides of the screw assembly (1) are provided with sealing rings (3) and are axially fixed by sealing caps (4) fixed inside the connecting plates (5). A double spring skeleton oil seal (43) is provided on the side of the sealing cap (4) away from the sealing rings (3). The double spring skeleton oil seal (43) is located on the outer circumference of the rotating shaft, thereby forming a mechanical sealing cavity between the bearing and the corresponding screw sleeve.

6. A high-pressure, self-priming, externally mounted double-suction twin-screw pump according to claim 5, characterized in that, The connecting plate (5) is provided with a vertical elongated hole (52) and a transverse connecting hole (53) connected to its bottom. The side wall of the sealing cover (4) is provided with a through hole one (41) and a through hole two (42) that are perpendicular to each other. The through hole one (41) is connected to the mechanical seal cavity, and the two ends of the through hole two (42) are connected to the through hole one (41) and the transverse connecting hole (53) respectively, thus forming a flow channel structure that has both cooling lubrication and high-pressure airflow purging functions.

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