A double-casing low-flow-resistance axial pipeline pump, control system and control method

Abstract

The application relates to the technical field of water pump structures, and discloses a double-shell low-flow-resistance axial pipeline pump, a control system and a control method, the axial pipeline pump comprising: a pipeline pump body, the outer shell of which serves as an inner layer pump shell of the axial pipeline pump; the pipeline pump body is integrated with a permanent magnet motor stator and a permanent magnet; a self-flow valve, which comprises an outer layer pump shell, two driving execution mechanisms and two half-ring plate-shaped valve plates, the outer layer pump shell is peripherally sleeved on the inner layer pump shell, and a self-flow channel is formed between the two layers of pump shells; the two valve plates are symmetrically arranged between the outer layer pump shell and the inner layer pump shell, and form a valve of the self-flow channel; the two driving execution mechanisms are respectively connected with the two valve plates through respective valve rods, and the driving execution mechanisms control the valve plates to stretch and shrink along the radial direction of the pipeline pump body. The axial pipeline pump, the control system and the control method can simultaneously reduce the flow resistance and the volume.

Description

Technical Field

[0001] This invention relates to the field of water pump structure technology, specifically to a double-casing, low-flow-resistance axial flow pipeline pump, its control system, and its control method. Background Technology

[0002] In the field of fluid pumping, axial flow pipeline pumps have attracted widespread attention due to their high efficiency, stability and low maintenance. However, existing axial flow pipeline pumps have certain limitations in terms of flow resistance and noise, especially for applications that require low flow resistance and low noise.

[0003] Specifically, in a gravity-flow cooling system, a pump flow channel is installed. When the ship is sailing, the pump resistance in the pump flow channel is part of the system resistance. Higher resistance results in lower flow rate, and the flow noise increases due to the obstruction of the pump blades. Furthermore, the pump in the pump flow channel is driven by an independent motor and connected to the pump shaft via a coupling; the through-shaft seal uses a combination of mechanical and packing seals, resulting in a complex overall structure, large size, and heavy weight.

[0004] In related technologies, in self-flowing cooling systems, those skilled in the art have designed a shielded pipeline pump to solve the problems of large size and heavy weight of the aforementioned water pumps. The shielded pipeline pump integrates a permanent magnet motor with the pump. The stator of the permanent magnet motor is arranged circumferentially at the pump casing, and a permanent magnet is attached to the outer edge of the impeller. The rotating magnetic field generated by the stator coil directly drives the permanent magnet to drive the impeller to do work, thereby driving the impeller to rotate and greatly reducing the volume of the pump unit.

[0005] However, shielded inline pumps still cannot meet the requirements for low flow resistance. Therefore, those skilled in the art urgently need to design an inline pump that can simultaneously meet the requirements of low flow resistance and small size for use in gravity-fed cooling systems. Summary of the Invention

[0006] This application provides a dual-casing, low-flow-resistance axial-flow pipeline pump, a control system, and a control method, which can simultaneously reduce flow resistance and decrease volume.

[0007] In a first aspect, embodiments of this application provide a dual-casing, low-flow-resistance axial-flow pipeline pump, comprising: a pipeline pump body, the outer casing of which serves as the inner pump casing of the axial-flow pipeline pump; the pipeline pump body integrates a permanent magnet motor stator and a permanent magnet.

[0008] The self-flow valve includes an outer pump casing, two drive actuators, and two semi-annular valve plates. The outer pump casing is spaced around the inner pump casing, and a self-flow channel is formed between the two pump casings. The two valve plates are symmetrically arranged between the outer and inner pump casings, forming a valve with a self-flow channel. The two drive actuators are connected to the two valve plates one by one through their respective valve stems. The drive actuators control the valve plates to extend and retract radially along the pipeline pump body.

[0009] In conjunction with the first aspect, in one embodiment, the axial flow pipeline pump has a low flow resistance mode, a pure pump flow mode, and a mixed flow mode. In the low flow resistance mode, the pipeline pump body is closed and the gravity flow channel is open. In the mixed flow mode, both the gravity flow channel and the pipeline pump body are open. In the pure pump flow mode, the gravity flow channel is closed and the pipeline pump body is open.

[0010] In the low-flow-resistance mode of the axial-flow pipeline of this application, the water flows through the self-flow channel without obstruction after the self-flow valve is opened, which greatly reduces the flow resistance and meets the low flow resistance requirement. In the mixed-flow mode, compared with the prior art which only has a pump flow channel, the mixed-flow mode of the axial-flow pipeline pump of this application also reduces the flow resistance and meets the low flow resistance requirement.

[0011] In conjunction with the first aspect, in one embodiment, the outer pump housing is provided with an embedding groove corresponding to the valve plate, which accommodates the valve plate when the drive actuator controls the valve plate to retract and open the self-flow channel.

[0012] In conjunction with the first aspect, in one embodiment, the pipeline pump body includes an outlet guide shield and an inlet guide shield, a rotatable pump shaft is disposed between the two guide shields, a pump rotor is disposed in the middle section of the pump shaft by a key, a double-layer bushing is disposed on one side of the middle section of the pump shaft, and a pump guide vane is disposed between the double-layer bushing and the inner pump casing; a permanent magnet is disposed at the end of the pump rotor away from the pump shaft, and a permanent magnet motor stator corresponding to the permanent magnet is disposed on the outer side of the inner pump casing.

[0013] The axial flow pipeline pump of this application integrates the permanent magnet motor stator and the permanent magnet into the pipeline pump body. The permanent magnet is set at the end of the pump rotor away from the pump shaft, and the permanent magnet motor stator corresponding to the permanent magnet is set on the outer side of the inner pump shell. The rotating magnetic field generated by the permanent magnet motor stator directly drives the permanent magnet to drive the impeller to do work, thereby driving the impeller to rotate. Compared with the traditional pump body structure, the volume of the pipeline pump body can be greatly reduced.

[0014] In conjunction with the first aspect, in one embodiment, a bearing is provided at one end of the pump shaft near the water inlet guide shroud, the bearing is pressed by bearing caps on both sides, and a bolt is radially inserted through the end of the pump shaft to limit the bearing.

[0015] In conjunction with the first aspect, in one embodiment, the outer pump casing and the inner pump casing are connected by intermittent pump casing connecting ribs.

[0016] Secondly, embodiments of this application provide a control system including the above-described axial flow pipeline pump, comprising:

[0017] A frequency converter, which is connected to the pipeline pump body via a signal line;

[0018] The controller is connected to the frequency converter and two drive actuators via signal lines. The controller controls the start and stop of the pipeline pump body and the speed adjustment through the frequency converter. The controller controls the opening and closing of the self-flow valve and the opening degree adjustment through the drive actuators.

[0019] In conjunction with the second aspect, in one embodiment, the outer pump housing is provided with an embedding groove corresponding to the valve plate, which accommodates the valve plate when the drive actuator controls the valve plate to retract and open the self-flow channel.

[0020] Thirdly, embodiments of this application provide a control method for the above-mentioned control system, comprising the following steps:

[0021] The controller receives the flow demand signal from the axial flow pipeline pump and selects its operating mode.

[0022] The pipeline pump body and / or gravity flow valve are opened and closed according to the working mode. If the low flow resistance mode is selected, the pipeline pump body is closed and the gravity flow channel is opened; if the mixed flow mode is selected, both the gravity flow channel and the pipeline pump body are opened; if the pure pump flow mode is selected, the gravity flow channel is closed and the pipeline pump body is opened.

[0023] Adjust the speed of the pipeline pump body and / or the opening of the gravity flow valve according to the flow demand signal.

[0024] In conjunction with the second aspect, in one embodiment, adjusting the rotational speed of the pipeline pump body and / or the opening degree of the gravity flow valve according to the flow demand signal further includes:

[0025] In low flow resistance mode, the controller adjusts two semi-annular valve plates through two drive actuators, causing the two semi-annular valve plates to extend and retract radially along the pipeline pump body, adjusting the opening of the gravity flow channel until the flow requirement is met.

[0026] In mixed-flow mode, the controller adjusts the speed of the pipeline pump body through the frequency converter; at the same time, the controller adjusts two semi-annular valve plates through two drive actuators, so that the two semi-annular valve plates extend and retract radially along the pipeline pump body, adjusting the opening of the gravity flow channel until the flow requirement is met.

[0027] In pure pump flow mode, the controller adjusts the speed of the pipeline pump body through the frequency converter until the flow requirement is met.

[0028] The beneficial effects of the technical solutions provided in this application include at least the following:

[0029] The axial-flow pipeline pump of this application integrates a permanent magnet motor stator and a permanent magnet into the pump body to drive the impeller rotation, significantly reducing the size of the pump body. Simultaneously, a double-shell design is employed, adding an outer pump shell outside the main pump body. This creates a self-flowing channel between the two shells, and two valve plates form a valve within this channel. Two drive actuators control the opening and closing of these two valve plates. The added self-flowing valve on the outer layer of the pump body greatly reduces flow resistance. This axial-flow pipeline pump of this application simultaneously reduces flow resistance and size, making it suitable for applications requiring low flow resistance and a small installation space, thus demonstrating strong practicality.

[0030] The control system and control method of this application simultaneously reduce flow resistance and reduce volume of the axial flow pipeline pump. The control system can achieve precise control. The controller controls the opening and closing of the pipeline pump body and the speed adjustment through the frequency converter. The controller controls the opening and closing of the self-flowing valve and the adjustment of the opening degree through the drive actuator. It is practical, flexible and convenient. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of an axial flow pipeline pump provided in an embodiment of this application;

[0033] Figure 2 This is a schematic diagram of the valve plate provided in an embodiment of this application;

[0034] Figure 3 A schematic diagram of the control system provided in an embodiment of this application;

[0035] Figure 4 A flowchart of the control method provided in the embodiments of this application;

[0036] In the diagram: 1. Outer pump casing; 2. Pump casing connecting rib; 3. Pump mounting panel; 4. Permanent magnet motor stator; 5. Permanent magnet; 6. Pump guide vane; 7. Drive actuator; 8. Valve stem; 9. Valve plate; 10. Outlet guide shroud; 11. Inner shaft sleeve; 12. Actuator mounting panel; 13. Sealing ring; 14. Key; 15. Pump rotor; 16. Bearing cover; 17. Bolt; 18. Inner pump casing; 19. Inlet guide shroud; 20. Bearing; 23. Pump shaft; 24. Outer shaft sleeve. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0038] This application provides a dual-casing, low-flow-resistance axial-flow pipeline pump, a control system, and a control method that can simultaneously meet the requirements of small size and low flow resistance.

[0039] Specifically, the application scenario of this application is a self-flowing cooling system, that is, when a ship is sailing, seawater will flow into the axial flow pipeline pump along the direction of sailing.

[0040] like Figure 1 and Figure 2 As shown, this application discloses a dual-casing, low-flow-resistance axial-flow pipeline pump, which includes a pipeline pump body and a self-flow valve.

[0041] The outer shell of the pipeline pump body serves as the inner pump casing 18 of the axial flow pipeline pump. The pipeline pump body integrates a permanent magnet motor stator 4 and a permanent magnet 5. The rotating magnetic field generated by the permanent magnet motor stator 4 directly drives the permanent magnet 5 to drive the impeller to do work, thereby driving the impeller to rotate and greatly reducing the volume of the pipeline pump body.

[0042] The self-flow valve comprises an outer pump casing 1, two drive actuators 7, and two semi-annular valve plates 9. The outer pump casing 1 is spaced around the inner pump casing 18, forming a self-flow channel between the two casings. The two valve plates 9 are symmetrically arranged between the outer pump casing 1 and the inner pump casing 18, with the two semi-annular plates forming a complete ring, creating a valve for opening and closing the self-flow channel. The two drive actuators 7 are connected to the two valve plates 9 one-to-one via their respective valve stems 8, and the drive actuators 7 control the radial extension and retraction of the valve plates 9 along the pipeline pump body to achieve valve opening and closing control. Specifically, the two semi-annular valve plates 9 enclose the inner pump casing 18 to form a complete ring.

[0043] The axial flow pipeline pump of this application achieves impeller rotation by integrating a permanent magnet motor stator 4 and a permanent magnet 5 into the pipeline pump body, which greatly reduces the volume of the pipeline pump body.

[0044] Simultaneously, a double-shell design is adopted, adding an outer pump shell 1 outside the main body of the pipeline pump, forming a self-flow channel between the two pump shells. Two valve plates 9 form a valve within this self-flow channel, and two drive actuators 7 control the opening and closing of the two valve plates 9. The newly added self-flow valve outside the main body of the pipeline pump significantly reduces flow resistance. This axial-flow pipeline pump of the present application can simultaneously reduce flow resistance and size, making it suitable for applications requiring low flow resistance and a small installation space, thus demonstrating strong practicality.

[0045] In one embodiment, the axial flow inline pump has three operating modes: low flow resistance mode, pure pump flow mode, and mixed flow mode. In pure pump flow mode, only the inline pump body operates, and it functions like a traditional water pump. The key features are the other two modes: low flow resistance mode and mixed flow mode.

[0046] In the low flow resistance mode, the pipeline pump body is closed and the gravity flow channel is open. At this time, the pipeline pump body does not provide power. The water flow of the gravity flow cooling system relies on the power generated by the ship's navigation to flow through the pipeline pump body and the gravity flow valve. Since the gravity flow valve is open, the water flow passes through the gravity flow channel without any obstructions, which greatly reduces the flow resistance and meets the low flow resistance requirement.

[0047] In mixed-flow mode, both the gravity flow channel and the pipeline pump body are open. At this time, the pipeline pump body provides power, and the water flow relies on the power generated by the ship's navigation and the power of the pipeline pump body to flow through the pipeline pump body and the gravity flow valve. Since after the gravity flow valve is opened, part of the water flows through the pipeline pump body and the other part flows through the gravity flow valve. Compared with the prior art which only has a pump flow channel, the mixed-flow mode of the axial flow pipeline pump of this application also reduces the flow resistance and meets the low flow resistance requirement.

[0048] In the low-flow-resistance mode of the axial-flow pipeline of this application, the water flows through the self-flow channel without obstruction after the self-flow valve is opened, which greatly reduces the flow resistance and meets the low flow resistance requirement. In the mixed-flow mode, compared with the prior art which only has a pump flow channel, the mixed-flow mode of the axial-flow pipeline pump of this application also reduces the flow resistance and meets the low flow resistance requirement.

[0049] In one embodiment, the outer pump housing 1 is provided with an embedded groove corresponding to the valve plate 9. When the drive actuator 7 controls the valve plate 9 to retract and open the self-flow channel, the embedded groove accommodates the valve plate 9, providing a structural basis for the radial extension and retraction of the valve plate 9 along the pipeline pump body.

[0050] Furthermore, the specific structure of the pipeline pump body integrating the permanent magnet motor stator 4 and the permanent magnet 5 is as follows:

[0051] The pipeline pump body includes an outlet guide shroud 10 and an inlet guide shroud 19. The outlet guide shroud 10 is used for outlet water guidance, and the inlet guide shroud 19 is used for inlet water guidance.

[0052] A rotatable pump shaft 23 is provided between the two guide shields. The middle section of the pump shaft 23 is connected to the pump rotor 15 via a key 14. A double-layer bushing is provided on one side of the middle section of the pump shaft 23. A pump guide vane 6 is provided between the double-layer bushing and the inner pump casing 18.

[0053] A permanent magnet 5 is provided at the end of the pump rotor 15 away from the pump shaft 23, and a permanent magnet motor stator 4 corresponding to the permanent magnet 5 is provided on the outer side of the inner pump casing 18.

[0054] The axial flow pipeline pump of this application integrates the permanent magnet motor stator 4 and the permanent magnet 5 into the pipeline pump body. The permanent magnet 5 is set at the end of the pump rotor 15 away from the pump shaft 23. The permanent magnet motor stator 4 corresponding to the permanent magnet 5 is set on the outer side of the inner pump shell 18. The rotating magnetic field generated by the permanent magnet motor stator 4 directly drives the permanent magnet 5 to drive the impeller to do work, thereby driving the impeller to rotate. Compared with the traditional pump body structure, the volume of the pipeline pump body can be greatly reduced.

[0055] Specifically, the double-layer bushing includes an inner bushing 11 and an outer bushing 24. The inner bushing 11 is fitted onto the pump shaft 23.

[0056] Specifically, the axial flow pipeline pump also includes a pump mounting panel 3 and an actuator mounting panel 12. The pump mounting panel 3 is used to fix the outer pump casing 1, and the actuator mounting panel 12 is used to fix the drive actuator 7.

[0057] Specifically, the drive actuator 7 is sealed to the outer pump housing 1 by a sealing ring 13.

[0058] Preferably, the drive actuator can be an electric actuator or a hydraulic actuator.

[0059] In one embodiment, a bearing 20 is provided at one end of the pump shaft 23 near the inlet guide shroud 19. The bearing 20 is pressed together by bearing caps 16 on both sides, and a bolt 17 is radially inserted through the end of the pump shaft 23 to limit the bearing 20. The bearing 20 can reduce rotational friction.

[0060] Preferably, the outer pump casing 1 and the inner pump casing 18 are connected by intermittent pump casing connecting ribs 2 to improve structural stability.

[0061] like Figure 3 As shown, this application also discloses a control system including the above-mentioned axial flow pipeline pump. The control system includes a frequency converter and a controller. The frequency converter is connected to the pipeline pump body through a signal line for precise control of the pipeline pump body.

[0062] The controller is connected to the frequency converter and the two drive actuators 7 via signal lines. The controller controls the opening and closing of the pipeline pump body and the speed adjustment through the frequency converter. The controller controls the opening and closing of the gravity valve and the opening degree adjustment through the drive actuators 7.

[0063] The control system of this application can achieve precise control while simultaneously reducing flow resistance and size of the axial flow pipeline pump. The controller controls the opening and closing of the pipeline pump body and the speed adjustment through the frequency converter; the controller controls the opening and closing of the self-flow valve and the adjustment of the opening degree through the drive actuator 7, which is practical, flexible and convenient.

[0064] Regarding the control system, in one embodiment, the outer pump housing 1 is provided with an embedded groove corresponding to the valve plate 9. When the drive actuator 7 controls the valve plate 9 to retract and open the self-flow channel, the embedded groove accommodates the valve plate 9, providing a structural basis for the radial extension and retraction of the valve plate 9 along the pipeline pump body.

[0065] like Figure 4 As shown, this application also discloses a control method for the above-mentioned control system, comprising the following steps:

[0066] The controller receives the flow demand signal from the axial flow pipeline pump and selects its operating mode.

[0067] The pipeline pump body and / or gravity flow valve are opened and closed according to the working mode. If the low flow resistance mode is selected, the pipeline pump body is closed and the gravity flow channel is opened; if the mixed flow mode is selected, both the gravity flow channel and the pipeline pump body are opened; if the pure pump flow mode is selected, the gravity flow channel is closed and the pipeline pump body is opened.

[0068] Adjust the speed of the pipeline pump body and / or the opening of the gravity flow valve according to the flow demand signal.

[0069] Furthermore, adjusting the speed of the pipeline pump body and / or the opening of the gravity valve according to the flow demand signal also includes:

[0070] In low flow resistance mode, the controller adjusts two semi-annular valve plates 9 through two drive actuators 7, causing the two semi-annular valve plates 9 to extend and retract radially along the pipeline pump body, adjusting the opening of the gravity flow channel until the flow requirement is met.

[0071] When the mixed flow mode is selected, both the gravity flow channel and the pipeline pump body are open. The controller adjusts the speed of the pipeline pump body through the frequency converter. At the same time, the controller adjusts the two semi-annular valve plates 9 through the two drive actuators 7, so that the two semi-annular valve plates 9 extend and retract radially along the pipeline pump body, adjusting the opening of the gravity flow channel until the flow requirement is met.

[0072] When the pure pump flow mode is selected, the gravity flow channel is closed, and the controller adjusts the speed of the pipeline pump body through the frequency converter until the flow requirement is met.

[0073] Preferably, the opening and closing of the pipeline pump body and its speed can also be adjusted manually, and the opening degree of the gravity flow valve can also be adjusted manually.

[0074] Preferably, whether the flow rate requirement is met is monitored by a flow meter installed in the self-flowing cooling system, and the flow meter is connected to the controller.

[0075] The control method of this application can flexibly switch between three working modes. In both low flow resistance mode and mixed flow mode, the volume of the axial flow pipeline pump is reduced while the flow resistance is lowered.

[0076] Regarding the control method, in one embodiment, the outer pump housing 1 is provided with an embedded groove corresponding to the valve plate 9. When the drive actuator 7 controls the valve plate 9 to retract and open the self-flow channel, the embedded groove accommodates the valve plate 9, providing a structural basis for the radial extension and retraction of the valve plate 9 along the pipeline pump body.

[0077] The specific structure of the pipeline pump body integrating the permanent magnet motor stator 4 and permanent magnet 5 is as follows:

[0078] The pipeline pump body includes an outlet guide shroud 10 and an inlet guide shroud 19. The outlet guide shroud 10 is used for outlet water guidance, and the inlet guide shroud 19 is used for inlet water guidance.

[0079] A rotatable pump shaft 23 is provided between the two guide shields. The middle section of the pump shaft 23 is connected to the pump rotor 15 via a key 14. A double-layer bushing is provided on one side of the middle section of the pump shaft 23. A pump guide vane 6 is provided between the double-layer bushing and the inner pump casing 18.

[0080] A permanent magnet 5 is provided at the end of the pump rotor 15 away from the pump shaft 23, and a permanent magnet motor stator 4 corresponding to the permanent magnet 5 is provided on the outer side of the inner pump casing 18.

[0081] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0082] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0083] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A double-casing, low-flow-resistance axial-flow pipeline pump, characterized in that, Include: The pipeline pump body has an outer shell that serves as the inner pump casing (18) of the axial flow pipeline pump; the pipeline pump body integrates a permanent magnet motor stator (4) and a permanent magnet (5). The self-flow valve includes an outer pump housing (1), two drive actuators (7), and two semi-annular valve plates (9). The outer pump housing (1) is spaced around the inner pump housing (18), and a self-flow channel is formed between the two pump housings. The two valve plates (9) are symmetrically arranged between the outer pump housing (1) and the inner pump housing (18) to form a valve with a self-flow channel. The two drive actuators (7) are connected to the two valve plates (9) one by one through their respective valve stems (8). The drive actuators (7) control the valve plates (9) to extend and retract radially along the pipeline pump body. The axial flow pipeline pump has a low flow resistance mode, a pure pump flow mode, and a mixed flow mode. In the low flow resistance mode, the pipeline pump body is closed and the gravity flow channel is open. In the mixed flow mode, both the gravity flow channel and the pipeline pump body are open. In the pure pump flow mode, the gravity flow channel is closed and the pipeline pump body is open.

2. The axial flow pipeline pump with low flow resistance and dual housing as described in claim 1, characterized in that: The outer pump housing (1) is provided with an embedded groove corresponding to the valve plate (9). When the drive actuator (7) controls the valve plate (9) to retract and open the self-flow channel, the embedded groove accommodates the valve plate (9).

3. The axial flow pipeline pump with low flow resistance and double casing as described in claim 1, characterized in that: The pipeline pump body includes an outlet guide shield (10) and an inlet guide shield (19). A rotatable pump shaft (23) is provided between the two guide shields. The middle section of the pump shaft (23) is connected to a pump rotor (15) via a key (14). A double-layer bushing is provided on one side of the middle section of the pump shaft (23). A pump guide vane (6) is provided between the double-layer bushing and the inner pump casing (18). A permanent magnet (5) is provided at one end of the pump rotor (15) away from the pump shaft (23), and a permanent magnet motor stator (4) corresponding to the permanent magnet (5) is provided on the outside of the inner pump casing (18).

4. The axial flow pipeline pump with low flow resistance and double casing as described in claim 3, characterized in that: A bearing (20) is provided at one end of the pump shaft (23) near the water inlet guide shroud (19). The bearing (20) is pressed by bearing caps (16) on both sides, and a bolt (17) is provided radially through the end of the pump shaft (23) to limit the bearing (20).

5. The axial flow pipeline pump with low flow resistance and double casing as described in claim 1, characterized in that: The outer pump casing (1) and the inner pump casing (18) are connected by intermittent pump casing connecting ribs (2).

6. A control system comprising the axial flow pipeline pump of claim 1, characterized in that, Include: A frequency converter, which is connected to the pipeline pump body via a signal line; The controller is connected to the frequency converter and two drive actuators (7) via signal lines. The controller controls the start and stop of the pipeline pump body and the speed adjustment via the frequency converter. The controller controls the opening and closing of the self-flow valve and the opening degree adjustment via the drive actuators (7).

7. The control system as described in claim 6, characterized in that: The outer pump housing (1) is provided with an embedded groove corresponding to the valve plate (9). When the drive actuator (7) controls the valve plate (9) to retract and open the self-flow channel, the embedded groove accommodates the valve plate (9).

8. A control method for the control system as described in claim 6, characterized in that, Includes the following steps: The controller receives the flow demand signal from the axial flow pipeline pump and selects its operating mode. The pipeline pump body and / or gravity flow valve are opened and closed according to the working mode. If the low flow resistance mode is selected, the pipeline pump body is closed and the gravity flow channel is opened; if the mixed flow mode is selected, both the gravity flow channel and the pipeline pump body are opened; if the pure pump flow mode is selected, the gravity flow channel is closed and the pipeline pump body is opened. Adjust the speed of the pipeline pump body and / or the opening of the gravity flow valve according to the flow demand signal.

9. The control method as described in claim 8, characterized in that, Adjusting the speed of the pipeline pump body and / or the opening of the gravity valve according to the flow demand signal also includes: In low flow resistance mode, the controller adjusts two semi-annular valve plates (9) through two drive actuators (7), so that the two semi-annular valve plates (9) extend and retract radially along the pipeline pump body, adjusting the opening of the gravity flow channel until the flow requirement is met. In mixed flow mode, the controller adjusts the speed of the pipeline pump body through the frequency converter; at the same time, the controller adjusts the two semi-annular valve plates (9) through two drive actuators (7), so that the two semi-annular valve plates (9) extend and retract radially along the pipeline pump body to adjust the opening of the gravity flow channel until the flow requirement is met. In pure pump flow mode, the controller adjusts the speed of the pipeline pump body through the frequency converter until the flow requirement is met.

Images