High-pressure three-screw pump

Abstract

The high-pressure three-screw pump comprises a pump body, a driving screw and a driven screw, the driving screw and the driven screw are arranged in the pump body, an inlet is formed in one end of the pump body, an outlet is formed in the other end of the pump body, and low-pressure cavities are formed in the positions, close to the inlet, of the driving screw and the driven screw. The positions, close to the outlet, of the driving screw and the driven screw are high-pressure cavities, and low-pressure balance systems are arranged at the two ends of the driven screw. The low-pressure balance system comprises a low-pressure balance cavity, the low-pressure balance cavity is located at the end, away from the inlet, of the driven screw, and the low-pressure balance cavity communicates with the low-pressure cavity through a flow channel. And the extrusion state of the driven screw is changed into an external stretching state through low-pressure balance, so that the friction between the driven screw and the lining is reduced, and the durability is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of screw pump technology, specifically a high-pressure three-screw pump. Background Technology

[0002] High-pressure screw pumps refer to screw pumps with operating pressures exceeding 10 MPa. Due to their advantages such as stable flow rate, balanced pressure, no pulsation, and low noise, they have become core fluid transport equipment in critical fields such as military, power, and shipbuilding. However, domestic high-pressure screw pump technology is currently nonexistent, and related needs are difficult to meet through domestically produced products.

[0003] However, current high-pressure screw pumps have many problems. The main problem is that the internal screw is prone to jamming under high pressure, making it impossible to run continuously. In addition, the pressure balance structure is unreasonable, resulting in uneven wear of the front and back of the screw, which further reduces the lifespan of the screw pump and increases the operating cost. Summary of the Invention

[0004] The purpose of this invention is to provide a high-pressure screw pump to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A high-pressure screw pump includes a pump body and a driving screw and a driven screw disposed within the pump body. The pump body has an inlet at one end and an outlet at the other end. The driving screw and the driven screw are located near the inlet in a low-pressure chamber and near the outlet in a high-pressure chamber. A low-pressure balancing system is provided at both ends of the driven screw. The low-pressure balancing system includes a low-pressure balancing chamber located at the end of the driven screw away from the inlet, and the low-pressure balancing chamber is connected to the low-pressure chamber through a flow channel.

[0006] As a further aspect of the present invention: a bushing is provided on the inner wall of the pump body, and both the driving screw and the driven screw are disposed within the bushing.

[0007] As a further aspect of the present invention: the bushing is made of composite ceramic material, and the driving screw and driven screw are made of hardened steel; the surfaces of the driving screw and driven screw are coated, the surface hardness of the driving screw and driven screw after coating is not less than HRC65, and the deformation after heat treatment is less than 0.01mm.

[0008] As a further aspect of the present invention: the bushing is made of composite ceramic material, and the driving screw and driven screw are made of hardened steel, with the matrix hardness not less than HRC30-35 after heat treatment.

[0009] As a further aspect of the present invention: the surface coating of the driving screw and the driven screw increases their self-lubricating properties and wear resistance, and the surface hardness after treatment is increased to not less than HRC65, and the axial deformation of the screw after heat treatment is ≤0.01mm.

[0010] As a further embodiment of the present invention: a front end cover is fixedly connected to the end of the pump body away from the inlet, a balance sleeve is coaxially arranged inside the front end cover, a shaft sleeve positioning sleeve is provided at the end of the high pressure chamber away from the inlet, and the low pressure balance chamber is located between the shaft sleeve positioning sleeve and the balance sleeve.

[0011] As a further embodiment of the present invention: both ends of the driven screw are provided with driven screw ends, and a driven screw bushing is sleeved on the driven screw end near the front end cover. The driven screw bushing is provided with a pressure guiding hole, and the low-pressure balance chamber is connected to the high-pressure chamber through the pressure guiding hole.

[0012] As a further embodiment of the present invention: a driven screw positioning sleeve is fixedly connected to one end of the pump body near the inlet, a pressure plate is fixedly connected to the driven screw positioning sleeve by a screw, a driven screw top block is provided on the pressure plate, and the driven screw end near the inlet is rotatably connected to the driven screw top block.

[0013] As a further embodiment of the present invention: a bearing seat is fixedly connected to the outer side of the front end cover; the end of the active screw away from the inlet passes through the bushing positioning sleeve, the low-pressure balance chamber, the balance sleeve, and the bearing seat to extend to the outside of the pump body; a mechanical seal is fitted on the active screw; the mechanical seal is located on the bearing seat near the front end cover; and a bearing is provided between the active screw and the bearing seat.

[0014] As a further aspect of the present invention: the gap between the driving screw and the driven screw, the gap between the driving screw and the driven screw and the bushing, and the gap between the driving screw and the balance sleeve are all less than 0.01 mm.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This application adopts a low-pressure balance structure, which can effectively solve the problem of pump jamming caused by screw deformation due to extrusion under high pressure. The low-pressure balance changes the driven screw from the extrusion state to the outward stretching state, thereby reducing the friction between the driven screw and the inner liner and greatly improving durability. In this application, the low-pressure balance structure controls the pressure difference between the front and rear ends of the screw to within 2MPa, improves the wear uniformity to within 1.2 times, and extends the service life of the equipment to more than 8000 hours, which is 2-3 times that of ordinary screw pumps. 2. This application employs a material combination of composite ceramic liner and hardened steel screw, coupled with 0.01mm-level clearance control, reducing component deformation rate by over 90% under high pressure, completely resolving the screw jamming problem, and achieving continuous operation stability of over 99.5%. High-precision clearance control: The meshing clearance between the driving and driven screws, the radial clearance between the screw and the composite ceramic liner, and the mating clearance between the driving screw and the balance sleeve are all machined using high-precision equipment, with dimensional tolerances controlled within 0.01mm, ensuring motion coordination under high pressure.

[0016] 3. The high-precision meshing and surface strengthening process reduces screw wear by 80%, and the clearance remains stable within 0.03mm for a long time. Within the pressure range of 10-30MPa, the flow fluctuation is ≤3%, which far exceeds the performance level of plunger pumps. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the screw pump shaft side in this embodiment; Figure 2 , Figure 3 This is a cross-sectional view of this embodiment; Figure 4 This is a schematic diagram of the screw pump explosion in this embodiment; Figure 5 This is a schematic diagram of the driven screw bushing structure in this embodiment; In the diagram: 1-Pump body, 2-Inlet, 3-Outlet, 4-Front end cover, 5-Driven screw positioning sleeve, 6-Bushing, 7-High pressure chamber, 8-Low pressure chamber, 9-Balance sleeve, 10-Shaft sleeve positioning sleeve, 11-Driven screw, 12-Driven screw, 13-Driven screw end, 14-Driven screw top block, 15-Pressure plate, 16-Pressure guide hole, 17-Driven screw shaft sleeve, 18-Bearing seat, 19-Bearing, 20-Mechanical seal, 21-Low pressure balance chamber. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1In this embodiment of the invention, a high-pressure screw pump includes a pump body 1 and a driving screw 11 and a driven screw 12 disposed within the pump body 1. A bushing 6 is provided on the inner wall of the pump body 1. The driving screw 11 and the driven screw 12 are both disposed within the bushing 6. One end of the pump body 1 is provided with an inlet 2 and the other end is provided with an outlet 3. The position of the driving screw 11 and the driven screw 12 near the inlet 2 is a low-pressure chamber 8, and the position of the driving screw 11 and the driven screw 12 near the outlet 3 is a high-pressure chamber 7. A driven screw positioning sleeve 5 is provided near the inlet 2 of the pump body 1, and a front end cover 4 and a bearing seat 18 are provided at the end of the pump body 1 away from the inlet 2.

[0020] The bushing 6 is made of composite ceramic material, while the driving screw 11 and driven screw 12 are made of hardened steel. The surfaces of the driving screw 11 and driven screw 12 are coated to increase their self-lubrication and wear resistance. After coating, the surface hardness of the driving screw 11 and driven screw 12 is not less than HRC65, and the deformation after heat treatment is less than 0.01 mm. In this embodiment, the bushing 6 is made of composite ceramic material, and the driving screw 11 and driven screw 12 are made of hardened steel. After tempering, the base hardness is not less than HRC30-35. The surfaces of the driving screw 11 and driven screw 12 are coated to enhance their self-lubrication and wear resistance. After treatment, the surface hardness is increased to not less than HRC65, and the axial deformation of the screws after heat treatment is ≤0.01 mm.

[0021] like Figure 2-5The driven screw 11 is provided with a low-pressure balancing system at both ends. The low-pressure balancing system includes a low-pressure balancing chamber 21. The low-pressure balancing chamber 21 is located at the end of the driven screw 12 away from the inlet 2. The low-pressure balancing chamber 21 is connected to the low-pressure chamber 8 through a flow channel. The flow channel can be set inside the pump body 1 or through an external pipe. This embodiment does not limit the specific flow channel arrangement. In this embodiment, a balance sleeve 9 is coaxially arranged inside the front cover 4. A bushing positioning sleeve 10 is provided at the end of the high pressure chamber 7 away from the inlet 2. The low pressure balance chamber 21 is located between the bushing positioning sleeve 10 and the balance sleeve 9. Both ends of the driven screw 12 are provided with driven screw ends 13. A driven screw bushing 17 is sleeved on the driven screw end 13 of the driven screw 12 near the front cover 4. A pressure guiding hole 16 is provided on the driven screw bushing 17. The low pressure balance chamber 21 is connected to the high pressure chamber 7 through the pressure guiding hole 16. A driven rod positioning sleeve 5 is fixedly connected to the end of the pump body 1 near the inlet 2. A pressure plate 15 is fixedly connected inside the driven rod positioning sleeve 5 through a screw. A driven screw top block 14 is provided on the pressure plate 15. The driven screw end 13 of the driven screw 12 near the inlet 2 is rotatably connected to the driven screw top block 14. This embodiment abandons the traditional method of liquid balancing in the high-pressure zone and designs a low-pressure balancing structure. A low-pressure balancing chamber 21 is designed at the end of the driven screw 12. The low-pressure balancing chamber 21 is connected to the low-pressure chamber 8 of the pump through a flow channel. Most of the axial force of the high-pressure liquid acting on the screw is balanced by the hydraulic pressure introduced into the low-pressure balancing chamber 21. Furthermore, the net force on the driven screw 12 is designed as a tensile force pointing in the direction of the pump outlet, thereby avoiding the driven screw 12 being pushed towards the suction end under high pressure, which would aggravate the wear between it and the bushing 6.

[0022] The end of the drive screw 11 furthest from the inlet 2 passes through the bushing positioning sleeve 10, the low-pressure balance chamber 21, the balance sleeve 9, and the bearing housing 18, extending to the outside of the pump body 1. It is then connected to a power unit, typically an electric motor. A mechanical seal 20 is fitted onto the drive screw 11, located on the bearing housing 18 near the front end cover 4. A bearing 19 is positioned between the drive screw 11 and the bearing housing 18. The clearances between the drive screw 11 and the driven screw 12, between the drive screw 11 and the driven screw 12 and the bushing 6, and between the drive screw 11 and the balance sleeve 9 are all less than 0.01 mm to ensure coordinated movement under high pressure.

[0023] In use, the invention operates by driving the active screw 11 to rotate, which in turn drives the driven screw 11 to rotate synchronously in the opposite direction through the meshing of the helical teeth. Fluid is drawn in from the inlet 2 and sealed within the cavity formed by the screw, bushing 6, and pump body 1. It is then pushed axially towards the outlet 3, where the pressure gradually increases to 10 MPa or higher before being discharged from the outlet 3, thus completing the pressurization process of the fluid, which functions as a pump. In this embodiment, a driven screw bushing 17 is provided between the high-pressure chamber 7 and the low-pressure balance chamber 21, and a pressure guide hole 16 is provided on the driven screw bushing 17. The low-pressure balance chamber 21 and the low-pressure chamber 8 are connected through a flow channel, which causes the hydraulic pressure in the low-pressure balance chamber 21 to tend to be the same as the pressure in the low-pressure chamber 8. A pressure difference will be generated between the high-pressure chamber 7 and the low-pressure balance chamber 21. Under the action of the pressure difference, part of the high-pressure fluid in the high-pressure chamber 7 will enter the low-pressure balance chamber 21 through the pressure guide hole 16. During this process, the high-pressure fluid in the high-pressure chamber 7 will generate an axial thrust on the driven screw bushing 17, and this thrust is in the same direction as the fluid flow. Since one end of the driven screw is in the low-pressure area and the other end is in the high-pressure area, a pressure pointing towards the low-pressure area will be generated under the action of pressure. This pressure will cause excessive wear on the low-pressure end of the driven screw 12, seriously affecting its service life. This application balances this pressure by using the thrust on the driven screw bushing, so that the driven screw changes from a compressive state to an outward stretching state. This reduces the friction between the driven screw and the inner liner, greatly improving durability. Due to the combined effect of high-precision fit, high-strength materials, ultra-hard coating and low-pressure balance structure, the pump operates smoothly throughout the entire working process without jamming, with minimal wear, and stable flow and pressure output.

[0024] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0025] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high pressure triple screw pump comprising a pump body (1) and a driving screw (11), a driven screw (12) disposed in the pump body (1), characterized in that, The pump body (1) is provided with an inlet (2) at one end and an outlet (3) at the other end, the positions of the driving screw (11) and the driven screw (12) close to the inlet (2) are low-pressure cavities (8), the positions of the driving screw (11) and the driven screw (12) close to the outlet (3) are high-pressure cavities (7), and the driven screw (11) is provided with a low-pressure balance system at both ends; The low-pressure balance system comprises a low-pressure balance cavity (21) arranged therein, the low-pressure balance cavity (21) is located at one end of the driven screw (12) away from the inlet (2), and the low-pressure balance cavity (21) is in communication with the low-pressure cavity (8) through a flow channel.

2. A high-pressure screw pump according to claim 1, characterized in that The inner wall of the pump body (1) is provided with a bushing (6), and the driving screw (11) and the driven screw (12) are arranged in the bushing (6).

3. A high-pressure screw pump according to claim 2, characterized in that The bushing (6) is made of composite ceramic material, the driving screw (11) and the driven screw (12) are made of hardened steel, the surfaces of the driving screw (11) and the driven screw (12) are provided with plating layers, the surface hardness of the driving screw (11) and the driven screw (12) after plating is not less than HRC65, and the deformation after heat treatment is less than 0.01mm.

4. A high-pressure screw pump according to claim 3, characterized in that The bushing (6) is made of composite ceramic material with Al2O3 content ≥99%, the driving screw (11) and the driven screw (12) are made of hardened steel, and the base body hardness after quenching and tempering treatment is not less than HRC30-35.

5. A high pressure screw pump according to claim 1, characterized in that The surfaces of the driving screw (11) and the driven screw (12) are plated, the surface hardness after treatment is improved to not less than HRC65, and the axial deformation of the screw after heat treatment is ≤0.01mm.

6. A high pressure triple screw pump according to claim 1, wherein, The pump body (1) is fixedly connected with a front end cover (4) at one end away from the inlet (2), the balance sleeve (9) is coaxially arranged in the front end cover (4), the shaft sleeve positioning sleeve (10) is arranged at one end of the high-pressure cavity (7) away from the inlet (2), and the low-pressure balance cavity (21) is located between the shaft sleeve positioning sleeve (10) and the balance sleeve (9).

7. A high pressure triple screw pump according to claim 6, wherein, The driven screw (12) is provided with a driven screw end head (13) at each end, the driven screw end head (13) of the driven screw (12) close to the front end cover (4) is sleeved with a driven screw sleeve (17), the driven screw sleeve (17) is provided with a pressure guide hole (16), and the low-pressure balance cavity (21) is in communication with the high-pressure cavity (7) through the pressure guide hole (16).

8. A high pressure triple screw pump according to claim 7, characterized in that The pump body (1) is fixedly connected with a driven rod positioning sleeve (5) at one end close to the inlet (2), the driven rod positioning sleeve (5) is fixedly connected with a pressing plate (15) through a screw rod, the pressing plate (15) is provided with a driven screw top block (14), and the driven screw end head (13) of the driven screw (12) close to the inlet (2) is rotatably connected with the driven screw top block (14).

9. A high pressure triple screw pump according to claim 6, wherein, The front end cover (4) is fixedly connected with a bearing seat (18) outside, one end of the driving screw (11) away from the inlet (2) extends to the outside of the pump body (1) through a shaft sleeve positioning sleeve (10), a low-pressure balance cavity (21), a balance sleeve (9), and the bearing seat (18), a mechanical seal (20) is sleeved on the driving screw (11), the mechanical seal (20) is located at the position of the bearing seat (18) close to the front end cover (4), and a bearing (19) is arranged between the driving screw (11) and the bearing seat (18).

10. A high pressure triple screw pump as claimed in claim 1, wherein, The gap between the driving screw (11) and the driven screw (12), the gap between the driving screw (11) and the driven screw (12) and the bushing (6), and the gap between the driving screw (11) and the balance sleeve (9) are all less than 0.01 mm.

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