Leakage-free three-screw pump

Abstract

The utility model discloses a leakage-free three-screw pump, which belongs to the technical field of screw pumps and comprises a pump body, a screw bushing is arranged in the pump body, a driving screw and two driven screws meshed on two sides of the driving screw are arranged in the screw bushing, a front cover is arranged on the end face of the pump body, and a connecting frame is arranged on the front cover. A driving motor used for driving the driving screw to rotate is arranged on the connecting frame, a magnetic coupling is arranged in the connecting frame, torque is transmitted between the driving screw and an output shaft of the driving motor through the magnetic coupling, the magnetic coupling comprises an outer magnetic sleeve and an inner magnetic sleeve arranged in the outer magnetic sleeve, and a spacer sleeve is arranged between the outer magnetic sleeve and the inner magnetic sleeve. A shaft head of the driving screw extends into the inner magnetic sleeve and is connected with the inner magnetic sleeve, and an output shaft of the motor extends into the outer magnetic sleeve and is connected with the outer magnetic sleeve. According to the utility model, the transmission without leakage or with extremely low leakage rate is realized, the environmental pollution caused by material leakage corrosion and the loss of precious rare earth elements are reduced, and the range of applicable media is enlarged.

Description

Technical Field

[0001] This utility model belongs to the field of screw pump technology, and in particular relates to a leak-free three-screw pump. Background Technology

[0002] Three-screw pumps are among the most important types of environmental protection pumps, with a wide range of applications spanning key industries such as petroleum, chemical, metallurgy, military, and light industry. This type of pump is specifically designed to handle a range of complex media, including but not limited to flammable, explosive, easily oxidized, and moisture-sensitive materials, as well as media that are carcinogenic, highly toxic, and strongly corrosive. Therefore, the sealing performance of a three-screw pump is not only a key indicator of the overall performance of the pump unit, but also an indispensable element in ensuring the safe and efficient operation of the pump unit.

[0003] Traditional three-screw pumps use mechanical seals, packing seals, and plug seals as shaft seals, each with varying degrees of permissible leakage. When the medium contains toxic, harmful, or highly reactive substances, the pump's operation is limited. Furthermore, traditional sealing structures require regular maintenance of the mechanical seal, increasing operating costs and potentially leading to decreased sealing performance due to improper maintenance or inaccurate timing. When the medium generates heat through friction during pump operation, and coking occurs on the heated sealing surface, the reliability of the mechanical seal is significantly reduced, making it prone to failure. Downtime for repairs due to mechanical seal failure results in substantial economic losses. In special operating conditions, pump body design is often severely limited, making it difficult to use conventional mechanical seals to prevent leakage. Summary of the Invention

[0004] To address the problems existing in the prior art, this utility model provides a leak-free three-screw pump, which features leak-free operation and static sealing, achieving leak-free or extremely low leakage rate transmission, reducing environmental pollution caused by material leakage and corrosion, as well as the loss of valuable rare earth elements, and increasing the range of applicable media.

[0005] This utility model is implemented as follows: a leak-free three-screw pump includes a pump body, a screw bushing inside the pump body, a driving screw and two driven screws meshing on both sides of the driving screw inside the screw bushing, a front cover on the end face of the pump body, a connecting frame on the front cover, one end of the driving screw penetrating the front cover and extending into the connecting frame, a drive motor for driving the driving screw to rotate on the connecting frame, and a magnetic coupling inside the connecting frame. The driving screw and the output shaft of the drive motor transmit torque through the magnetic coupling. The magnetic coupling includes an outer magnetic sleeve and an inner magnetic sleeve disposed inside the outer magnetic sleeve, a spacer sleeve is disposed between the outer magnetic sleeve and the inner magnetic sleeve, the shaft end of the driving screw extends into and connects to the inner magnetic sleeve, and the output shaft of the drive motor extends into and connects to the outer magnetic sleeve.

[0006] Furthermore, a bearing housing is installed within the connecting frame near the pump body, and a bearing is installed within the bearing housing. The bearing is sleeved on the drive screw. A transition flange is provided between the spacer sleeve and the bearing housing, and an O-ring is provided on the end face of the spacer sleeve that fits against the transition flange. The transition flange is used to transition between the stuffing box stop and the spacer sleeve stop, which are limited by design space.

[0007] Furthermore, the bearing housing is provided with an oil return structure, which includes an oil return chamber that is connected to the inner cavity of the bearing housing. The inlet end of the oil return chamber abuts against a valve ball, and an oil return valve plug is provided in the oil return chamber located on the same axis as the valve ball. A spring is provided between the oil return valve plug and the valve ball.

[0008] A bushing is provided at the end of the driven screw near the front cover. A first oil return channel is provided inside the bushing. A second oil return channel is provided on the front cover. One end of the second oil return channel is connected to the oil return chamber, and the other end is connected to the first oil return channel.

[0009] Furthermore, the active screw is provided with a flow channel, one end of which is connected to the outlet cavity of the pump body, and the other end extends to the end face of the shaft head. The shaft head end of the pump body is designed with a central hole, and a perforated plug is installed in the central hole. The flow channel improves the efficiency of medium flow and facilitates the dissipation of heat between the inner magnetic sleeve and the spacer sleeve. The central hole at the shaft head end serves two purposes: firstly, it is used during the machining process, and secondly, it is used to connect the perforated plug to facilitate the passage of small amounts of medium.

[0010] Furthermore, the inner cavity of the outer magnetic sleeve is provided with a baffle, and a screw is provided on the baffle. The screw passes through the baffle and connects to the motor shaft of the drive motor. The structure of the baffle and screw inside the outer magnetic sleeve restricts the axial position of the outer magnetic sleeve, especially when the unit is used vertically, it can prevent the outer magnetic sleeve from falling off under the action of gravity.

[0011] Furthermore, a bent plate is provided on one side of the connecting frame, and the bent plate is bolted to the connecting frame. The separate design of the connecting frame and the bent plate facilitates flexible installation and use, allowing for both horizontal and vertical installation.

[0012] Furthermore, a first gasket is provided between the pump body and the front cover, and a second gasket is provided between the screw bushing and the front cover.

[0013] Furthermore, a third gasket is provided between the bearing housing and the front cover, and a fourth gasket is provided between the bearing housing and the transition flange.

[0014] The advantages and technical effects of this utility model are as follows: Due to the adoption of the above technical solution, it has the characteristics of no leakage and static sealing, realizing the transmission with no leakage or extremely low leakage rate, reducing the pollution caused by material leakage and corrosion to the environment and the loss of precious rare earth elements, and increasing the range of applicable media. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure provided in an embodiment of the present utility model;

[0016] Figure 2 This is a partial structural schematic diagram provided in an embodiment of the present utility model.

[0017] In the diagram: 1. Pump body; 2. Screw bushing; 3. Front cover; 4. Driving screw; 5. Driven screw; 6. Shaft sleeve; 7. Bearing housing; 8. Bearing; 9. Transition flange; 10. Inner magnetic sleeve; 11. Spacer sleeve; 12. Outer magnetic sleeve; 13. Baffle; 14. Washer; 15. Shaft retaining ring; 16. First connecting key; 17. Second connecting key; 18. Screw; 19. Connecting frame; 20. Bend plate; 21. Drive motor; 22. Plug with hole; 23. First gasket; 24. Second gasket; 25. Third gasket; 26. Fourth gasket; 27. Valve ball; 28. Spring; 29. ​​Return valve plug; 30. O-ring seal. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0019] It should be noted that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] like Figure 1 and Figure 2As shown, this application provides a leak-free three-screw pump, including a pump body 1. A screw bushing 2 is provided inside the pump body. A driving screw 4 and two driven screws 5 meshing on both sides of the driving screw are provided inside the screw bushing. A front cover 3 is provided on the end face of the pump body. A connecting frame 19 is provided on the front cover. One end of the driving screw 4 extends through the front cover into the connecting frame. A drive motor 21 for driving the driving screw to rotate is provided on the connecting frame. A magnetic coupling is provided inside the connecting frame. The driving screw 4 and the output shaft of the drive motor 21 transmit torque through the magnetic coupling. The magnetic coupling includes an outer magnetic sleeve 12 and an inner magnetic sleeve 10 disposed inside the outer magnetic sleeve. A spacer sleeve 11 is provided between the outer magnetic sleeve and the inner magnetic sleeve. The shaft end of the driving screw 4 extends into the inner magnetic sleeve and is connected to the inner magnetic sleeve through a first connecting key 16. The output shaft of the drive motor 21 extends into the outer magnetic sleeve 12 and is connected to the outer magnetic sleeve through a second connecting key 17. Specifically, the radial fit dimensions between the pump body 1, front cover 3, and screw bushing 2 are controlled by a stop, and standard parts are used for connection and fastening, with sealing gaskets to prevent leakage. A connecting bracket 19 connects the drive motor and the pump body end, with stop designs at both ends. The gap between the outer magnetic sleeve 12 and the spacer sleeve 11 is controlled by the stop to ensure uniform magnetic field distribution and prevent interference between parts. Preferably, a first gasket 23 is provided between the pump body 1 and the front cover 3, and a second gasket 24 is provided between the screw bushing 2 and the front cover.

[0021] A bearing housing 7 is installed inside the connecting frame 19 near the pump body 1. A bearing 8 is installed inside the bearing housing and is mounted on the drive screw 4. Specifically, the bearing is positioned and installed on the drive screw using washers 14 and shaft retaining rings 15. A transition flange 9 is provided between the spacer sleeve 11 and the bearing housing, and an O-ring seal 30 is provided on the end face of the spacer sleeve that fits against the transition flange. The transition flange is used to transition between the stuffing box stop and the spacer sleeve stop, which are limited by design space. Preferably, the front cover 3 and the bearing housing 7 are connected by a stop joint. A third gasket 25 is provided between the bearing housing 7 and the front cover 3, and a fourth gasket 26 is provided between the bearing housing and the transition flange 9.

[0022] The bearing housing 7 is equipped with an oil return structure, which includes an oil return chamber connected to the inner cavity of the bearing housing. A valve ball 27 abuts against the inlet end of the oil return chamber. An oil return valve plug 29 is located within the oil return chamber on the same axis as the valve ball, and a spring 28 is positioned between the oil return valve plug and the valve ball. A bushing 6 is located at the end of the driven screw 5 near the front cover side. A first oil return channel is provided within the bushing 6, and a second oil return channel is provided on the front cover 3. One end of the second oil return channel is connected to the oil return chamber, and the other end is connected to the first oil return channel. When the medium fills the spacer sleeve 11, transition flange 9, and bearing housing 7, and the pressure exceeds the pressure that the spring 28 can withstand, the valve ball 27 opens, allowing the medium to flow through the first and second oil return channels into the inlet cavity. This structure keeps the spacer sleeve 11 filled with medium and also removes heat generated by eddies, preventing heat accumulation.

[0023] The active screw 4 has a flow channel, one end of which connects to the outlet cavity of the pump body, and the other end extends to the shaft end face. The shaft end of the pump body has a central hole with a perforated plug 22 inside. When the inner and outer magnetic sleeves 12 rotate, the spacer sleeve 11 is in an alternating magnetic field. The direction and magnitude of the magnetic field change instantaneously according to a certain law, that is, the magnetic flux in the spacer sleeve wall changes with time. As a conductor, eddy currents, i.e., circular currents, are generated around the direction of the change in magnetic flux. During normal operation of the spacer sleeve 11 sealing magnetic coupling transmission device, heat is continuously released due to the generation of eddy currents. The accumulation of this heat will affect the normal operation of the magnetic device. Therefore, the flow channel can improve the efficiency of medium flow. With the help of pressure difference, some of the medium flows out from the shaft end, through the gap between the inner magnetic sleeve and the spacer sleeve 11, the transition flange 9, the oil return structure on the bearing housing 7, and the screw bushing 2 back to the inlet cavity, thus dispersing heat. This is beneficial for heat dissipation between the inner magnetic sleeve 10 and the spacer sleeve 11. A center hole is designed at the shaft end for use during processing and for connecting the perforated plug 22 to facilitate the passage of small amounts of medium.

[0024] The inner cavity of the outer magnetic sleeve 12 is provided with a baffle 13, and a screw 18 is provided on the baffle. The screw passes through the baffle and connects to the motor shaft of the drive motor 21. The structure of the baffle and screw inside the outer magnetic sleeve restricts the axial position of the outer magnetic sleeve, especially when the unit is used vertically, it can prevent the outer magnetic sleeve from falling off under the action of gravity.

[0025] A bent plate 20 is provided on one side of the connecting frame 19, and the bent plate is bolted to the connecting frame. The connecting frame and the bent plate are designed separately, which facilitates flexible installation and use, and can be used for both horizontal and vertical installation.

[0026] Work process:

[0027] The drive motor 21 is connected to the pump body 1 without contact, achieving contactless drive through magnetic force. The medium inside the pump is sealed within the spacer sleeve by a gasket or O-ring 30, achieving a leak-free effect. The outer magnetic sleeve 12 rotates with the drive motor 21, and the magnetic field of the inner magnetic sleeve 10 interacts with the magnetic field of the outer magnetic sleeve. The inner magnetic sleeve is connected to the shaft of the drive screw 4 through the first connecting key 16 and rotates with the outer magnetic field. Under the action of the inner magnetic sleeve, the drive screw rotates synchronously with the drive motor 21, thereby realizing the operation of the pump end.

[0028] The driving screw 4 and driven screw 5 mesh and cooperate with the screw bushing 2 to form a closed cavity. As the screws rotate, the closed cavity draws in liquid into the pump inlet, and after closing, the liquid-filled closed cavity smoothly delivers the liquid axially to the pump outlet. Through the continuous rotation of the screws, the closed cavity continuously discharges the liquid.

[0029] Due to the adoption of the above technical solution, it has the characteristics of no leakage and static sealing, realizing transmission with no leakage or extremely low leakage rate, reducing the pollution caused by material leakage and corrosion to the environment and the loss of precious rare earth elements, and increasing the range of applicable media.

[0030] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A leak-free three-screw pump, comprising a pump body, a screw bushing disposed within the pump body, a driving screw and two driven screws meshing on both sides of the driving screw disposed within the screw bushing, a front cover disposed on the end face of the pump body, a connecting frame disposed on the front cover, one end of the driving screw penetrating the front cover and extending into the connecting frame, and a drive motor for driving the driving screw to rotate disposed on the connecting frame, characterized in that... A magnetic coupling is provided inside the connecting frame. The drive screw and the output shaft of the drive motor transmit torque through the magnetic coupling. The magnetic coupling includes an outer magnetic sleeve and an inner magnetic sleeve disposed inside the outer magnetic sleeve. A spacer sleeve is provided between the outer magnetic sleeve and the inner magnetic sleeve. The shaft head of the drive screw extends into and is connected to the inner magnetic sleeve. The output shaft of the drive motor extends into and is connected to the outer magnetic sleeve.

2. The leak-free three-screw pump according to claim 1, characterized in that, A bearing housing is provided in the connecting frame near the pump body, and a bearing is provided in the bearing housing. The bearing is sleeved on the drive screw. A transition flange is provided between the spacer sleeve and the bearing housing, and an O-ring is provided on the end face of the spacer sleeve that fits against the transition flange.

3. The leak-free three-screw pump according to claim 2, characterized in that, The bearing housing is provided with an oil return structure, which includes an oil return chamber that is connected to the inner cavity of the bearing housing. The inlet end of the oil return chamber abuts against a valve ball. An oil return valve plug is provided in the oil return chamber located on the same axis as the valve ball. A spring is provided between the oil return valve plug and the valve ball. A bushing is provided at the end of the driven screw near the front cover. A first oil return channel is provided inside the bushing. A second oil return channel is provided on the front cover. One end of the second oil return channel is connected to the oil return chamber, and the other end is connected to the first oil return channel.

4. The leak-free three-screw pump according to claim 1, characterized in that, The active screw is provided with a flow channel. One end of the flow channel is connected to the outlet cavity of the pump body, and the other end extends to the end face of the shaft head. The shaft head end of the pump body is designed with a central hole, and a plug with a hole is provided in the central hole.

5. The leak-free three-screw pump according to claim 2, characterized in that, The inner cavity of the outer magnetic sleeve is provided with a baffle, and a screw is provided on the baffle. The screw passes through the baffle and is connected to the motor shaft of the drive motor.

6. The leak-free three-screw pump according to claim 1, characterized in that, A bent plate is provided on one side of the connecting frame, and the bent plate is bolted to the connecting frame.

7. The leak-free three-screw pump according to claim 1, characterized in that, A first gasket is provided between the pump body and the front cover, and a second gasket is provided between the screw bushing and the front cover.

8. The leak-free three-screw pump according to claim 2, characterized in that, A third gasket is provided between the bearing housing and the front cover, and a fourth gasket is provided between the bearing housing and the transition flange.

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