Permanent magnet frequency conversion self-suction type multi-stage centrifugal pump

Abstract

The invention relates to the technical field of multi-stage centrifugal pumps, and discloses a permanent magnet frequency conversion self-suction type multi-stage centrifugal pump. The water pump comprises a permanent magnet variable frequency motor and a pump body provided with a water inlet and a water outlet, a guide vane set composed of an inlet guide vane and a plurality of impeller guide vanes is fixedly arranged in the pump body, and a rotor fixedly connected with an output shaft of the permanent magnet variable frequency motor is rotationally arranged in the guide vane set. Impellers fixedly connected with the rotor are arranged in the impeller guide vanes; a pressure cavity is formed between the guide vane set and the pump body, a backflow opening used for being communicated with the pressure cavity is formed in the inlet guide vane, and a control valve is arranged in the backflow opening. By improving the structural relationship between the pump body and the guide vane group, a composite pressure cavity is formed between the pump body and the guide vane group, and the reflux inlet and the control valve are arranged between the pressure cavity and the inlet guide vane, so that a flow guarantee mechanism is formed, the total output flow of the centrifugal pump is ensured to be higher than the minimum continuous flow, and cavitation at the inlet of the first-stage impeller is avoided from the source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-stage centrifugal pumps, and particularly relates to a permanent magnet variable frequency self-priming multi-stage centrifugal pump. BACKGROUND

[0002] The self-priming multi-stage centrifugal pump is a kind of high-efficiency fluid conveying equipment, which ingeniously integrates the self-priming function and the multi-stage pressure boosting technology. The core feature is that by connecting a plurality of specially designed first-stage impellers provided with inducer wheels or having special anti-cavitation structures, the liquid pressure is gradually increased on the basis of realizing rapid self-priming, and finally the head and outlet pressure far exceeding that of a single-stage centrifugal pump are achieved, thereby meeting the needs of high-rise water supply, industrial processes and other stable high-head water supply.

[0003] However, the performance and reliability of the pump type are deeply affected by the stability of the inlet working condition (water supply) during actual operation. Any abnormal fluctuation or failure of the water supply pipeline (such as blockage of the filter / strainer, incomplete opening of the valve or presence of foreign matter in the pipeline, etc.) will cause the effective net positive suction head (NPSHa) of the centrifugal pump to decrease sharply. Since the pressure in the centrifugal pump increases gradually from the inlet to the outlet, the first-stage impeller inlet area becomes the "short board" link with the lowest pressure in the entire pump system. When the pressure at this point falls below the saturated vapor pressure of the transported liquid, serious cavitation erosion will occur.

[0004] The occurrence of cavitation not only produces intense vibration and noise, indicating abnormal operation of the equipment, but also causes continuous erosive damage to the material of the impeller (especially the first-stage impeller), leading to a decrease in efficiency, performance degradation, and ultimately a significant reduction in the service life of the centrifugal pump and an increase in maintenance costs.

[0005] Therefore, it is necessary to provide a permanent magnet variable frequency self-priming multi-stage centrifugal pump which can better adapt to fluctuations in the water supply pipeline. SUMMARY

[0006] To solve the above technical problems, the present application provides a permanent magnet variable frequency self-priming multi-stage centrifugal pump.

[0007] The present application adopts the following technical solutions: a permanent magnet variable frequency motor and a pump body provided with a water inlet and a water outlet, a guide vane group composed of an inlet guide vane and a plurality of impeller guide vanes is fixedly arranged in the pump body, a rotor fixedly connected with the output shaft of the permanent magnet variable frequency motor is rotatably arranged in the guide vane group, and an impeller fixedly connected with the rotor is arranged in each of the plurality of impeller guide vanes. A pressure chamber is formed between the guide vane group and the pump body, a backflow port for communicating the pressure chamber is arranged on the inlet guide vane, a control valve is arranged in the backflow port, the control valve comprises a stop block arranged on the inlet guide vane, a valve body is slidably arranged on the stop block, and a first spring with two ends abutting against the stop block and the valve body is sleeved on the valve body. When the water supply is insufficient to cause the pressure in the pressure chamber to weaken and fail to tightly close the control valve, the control valve is opened to allow the fluid in the pressure chamber to be shunted to the inlet guide vane through the backflow port, so that the total output flow in the pump body is maintained above the minimum continuous flow.

[0008] As a further improvement of the above-mentioned scheme, a check valve is arranged in the water inlet and the water outlet of the pump body.

[0009] As a further improvement of the above-mentioned scheme, the check valve comprises a connecting ring, a stop valve is slidingly installed in the connecting ring, and a second spring is sleeved on the stop valve and abuts against both ends of the stop valve.

[0010] As a further improvement of the above-mentioned scheme, a pressure relief pipe is arranged on the backflow port and communicates the pressure chamber with the inlet guide vane, a telescopic frame is rotatably arranged on the backflow port and used to block both ends of the pressure relief pipe, and a top end of the telescopic frame is rotatably connected with the check valve in the water inlet, so that when the water supply in the pump body is reduced to cause the stop valve to move back, the telescopic frame is tilted and the bottom end of the telescopic frame is lifted to unblock both ends of the pressure relief pipe, so that the backflow of the water in the pressure chamber is completed in advance.

[0011] As a further improvement of the above-mentioned scheme, a flow guide plate is further arranged in the inlet guide vane, so as to guide the backflow of the water and avoid the backflow of the water colliding with the water flowing into the water inlet to cause turbulence and affect the conveying efficiency.

[0012] As a further improvement of the above-mentioned scheme, two notches are arranged on the flow guide plate and used to avoid the telescopic frame, so as to avoid interfering with the tilting movement of the telescopic frame.

[0013] As a further improvement of the above-mentioned scheme, a through slot is arranged on the bottom of the valve body and used to fit the pressure relief pipe, so that the pressure relief pipe will not limit the lifting opening, and the pressure relief pipe can ensure the stability of the bottom end.

[0014] As a further improvement of the above-mentioned scheme, a pressure tank is arranged on the water outlet of the pump body, and the installation height of the pressure tank is higher than the installation height of the check valve in the water outlet, so that not only the water hammer impact generated when the centrifugal pump is closed can be absorbed, but also the water storage characteristic can release the stored water to supplement the system after the water body backflow caused by the fluctuation of the water supply supplements the inlet flow, so as to prevent the pressure of the water supply system from sharply decreasing.

[0015] As a further improvement of the above-mentioned scheme, the pressure tank comprises a tank body and a diaphragm arranged in the tank body, and a gas chamber for filling nitrogen is formed between the diaphragm and the tank body.

[0016] Compared with the prior art, the beneficial effects of the present application are as follows: By improving the structural relationship between the pump body and the guide vane assembly, a composite pressure chamber is formed between them. A return port and a control valve are installed between the pressure chamber and the inlet guide vane, constituting a flow guarantee mechanism. When the water supply is insufficient or fluctuates, the pressure in the pressure chamber weakens, and the control valve opens the return port, diverting the fluid in the pressure chamber to the inlet guide vane. This ensures that the total output flow of the centrifugal pump is higher than the minimum continuous flow, fundamentally preventing cavitation at the inlet of the first-stage impeller. Furthermore, no electrical control components are required; the mechanical automatic control offers fast response and high reliability, reducing maintenance costs and ensuring stable operation of the centrifugal pump. The check valve, telescopic frame, and pressure relief pipe at the inlet work together to form a linkage system for early warning and rapid pressure relief. When the water supply fluctuates, the plug valve of the check valve at the inlet moves back, causing the telescopic frame to tilt and release the blockage on the pressure relief pipe. This allows the fluid in the pressure chamber to enter the inlet guide vane in advance to relieve pressure, and allows the control valve to return in advance. This compensates for the response delay of the traditional mechanism and solves the problem of temporary cavitation of the guide vane group. At the same time, the guide plate guides the return water to avoid turbulence affecting the delivery efficiency. The pressure tank, with its special structure and installation height, achieves a dual function. During normal operation, excess water flows into the tank for storage; when fluctuations in water supply cause a decrease in outlet pressure, the water in the tank is quickly released to replenish pressure, preventing a sudden drop in the water supply system pressure. When the centrifugal pump is shut down, the diaphragm inside the tank absorbs water hammer energy through elastic deformation, buffering pressure fluctuations, protecting the centrifugal pump, valves, and pipelines, extending system life, and reducing maintenance costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the overall structure of the permanent magnet variable frequency self-priming multistage centrifugal pump of the present invention; Figure 2 This is a disassembled view of the permanent magnet variable frequency self-priming multistage centrifugal pump of the present invention; Figure 3 This is a side plan sectional view of the permanent magnet variable frequency self-priming multistage centrifugal pump of the present invention; Figure 4 for Figure 3 A diagram showing the pump body section; Figure 5 This is a disassembled view of the permanent magnet variable frequency self-priming multistage centrifugal pump of the present invention; Figure 6 This is a cross-sectional view of the permanent magnet variable frequency self-priming multistage centrifugal pump of the present invention; Figure 7 This is a breakdown diagram of the guide vane assembly; Figure 8 This is a cross-sectional view of the inlet guide vane and check valve. Figure 9 This is a cross-sectional view of the pump body and guide vane assembly. Figure 10 This is a cross-sectional view of the imported guide vane.

[0018] List of principal symbols: 1, permanent magnet variable frequency motor; 2, pump body; 201, water inlet; 202, water outlet; 203, discharge port; 3, guide vane group; 301, inlet guide vane; 3011, backflow port; 3012, flow guide plate; 302, impeller guide vane; 3021, discharge port; 4, rotor; 5, impeller; 6, pressure chamber; 7, check valve; 701, connecting ring; 702, block valve; 703, second spring; 8, control valve; 801, stop block; 802, valve body; 8021, through slot; 803, first spring; 9, telescopic support; 10, pressure relief pipe; 11, pressure tank; 1101, tank body; 1102, diaphragm; 1103, air chamber; 12, pressure sensor. DETAILED DESCRIPTION

[0019] The application will be further described below in conjunction with the drawings and specific embodiments.

[0020] Please refer to Figures 1 to 10 , permanent magnet variable frequency self-suction multi-stage centrifugal pump, comprising: permanent magnet variable frequency motor 1 and pump body 2 provided with water inlet 201 and water outlet 202, pump body 2 is further provided with discharge port 203 below water inlet 201, discharge port 203 can be used to discharge water and sediment accumulated in pump body 2, water outlet 202 of pump body 2 is detachable multi-way pipe, pressure sensor 12 is further provided on the multi-way pipe, pressure sensor 12 is used to detect the pressure in water outlet 202, and the system is protected when the pressure in water outlet 202 is too high. Pump body 2 is fixedly connected with the output flange of permanent magnet variable frequency motor 1 through bolts, the bottom of permanent magnet variable frequency motor 1 is fixedly installed with a base, the base is provided with a shell wrapping the body, guide vane group 3 composed of one inlet guide vane 301 and a plurality of impeller guide vanes 302 is fixedly arranged in pump body 2, a plurality of annularly distributed discharge ports 3021 are arranged on the last impeller guide vane 302, so as to communicate impeller guide vane 302 with pressure chamber 6, rotor 4 fixedly connected with the output shaft of permanent magnet variable frequency motor 1 is rotatably arranged in guide vane group 3, and impeller 5 fixedly connected with rotor 4 is arranged in each of a plurality of impeller guide vanes 302; Please refer to Figure 6 , pressure chamber 6 is formed between guide vane group 3 and pump body 2, backflow port 3011 for communicating pressure chamber 6 is arranged on inlet guide vane 301, control valve 8 is arranged in backflow port 3011, control valve 8 comprises stop block 801 fixedly arranged on flow guide plate 3012 in inlet guide vane 301, valve body 802 is slidably arranged on stop block 801, and first spring 803 abutting at both ends is sleeved on valve body 802; When the water supply is insufficient to cause the pressure in the pressure chamber 6 to weaken and fail to tightly close the control valve 8, the control valve 8 is opened to allow the fluid in the pressure chamber 6 to flow through the backflow port 3011 into the inlet guide vane 301, so that the total output flow in the pump body 2 is maintained above the minimum continuous flow.

[0021] Through the above technical scheme, the structure relationship between the pump body 2 and the guide vane group 3 is improved to form a composite pressure chamber 6 therebetween, and the backflow port 3011 and the control valve 8 are arranged between the pressure chamber 6 and the inlet guide vane 301 to form a flow guarantee mechanism. When the water supply is insufficient or fluctuates, the pressure in the pressure chamber 6 weakens, the control valve 8 is opened to allow the fluid in the pressure chamber 6 to flow into the inlet guide vane 301 through the backflow port 3011, and the total output flow of the centrifugal pump is ensured to be higher than the minimum continuous flow, thereby avoiding the first-stage impeller 5 inlet cavitation from the root. Without the need for an electric control assembly, the mechanical automatic control has fast response and high reliability, reduces maintenance cost, and guarantees stable operation of the centrifugal pump.

[0022] Please refer to Figure 3 , Figure 4 and Figure 8 , the water inlet 201 and the water outlet 202 of the pump body 2 are both provided with a check valve 7, the check valve 7 includes a connecting ring 701, a stop valve 702 is slidingly installed in the connecting ring 701, and two second springs 703 are sleeved on the stop valve 702 and abut against both ends of the stop valve 702.

[0023] Please refer to Figures 8 to 10 , the backflow port 3011 is provided with a pressure relief pipe 10 communicating the pressure chamber 6 and the inlet guide vane 301, the middle part of the pressure relief pipe 10 is provided with two through holes, the fluid in the pressure chamber 6 can enter the pressure relief pipe 10 through the through holes and be discharged from both ends of the pressure relief pipe 10 into the inlet guide vane 301, the backflow port 3011 is rotatably provided with an extension frame 9 used for plugging both ends of the pressure relief pipe 10, the extension frame 9 is composed of two sleeve strips connected through a connecting shaft and two extension strips slidingly installed in the sleeve strips, the two sleeve strips are rotatably connected with the check valve 7 in the water inlet 201 through the connecting shaft, and the two extension strips are rotatably connected with the backflow port 3011, so that when the water supply in the pump body 2 is reduced to cause the stop valve 702 to move back, the extension frame 9 is tilted and the bottom end of the extension frame 9 is lifted to unplug both ends of the pressure relief pipe 10, thereby completing the backflow of the water in the pressure chamber 6 in advance.

[0024] Through the above technical scheme, the check valve 7 of the water inlet 201, the extension frame 9 and the pressure relief pipe 10 cooperate to form a linkage system for early warning and rapid pressure relief. When the water supply fluctuates, the stop valve 702 of the check valve 7 of the water inlet 201 moves back to tilt the extension frame 9 and unplug the pressure relief pipe 10, so that the fluid in the pressure chamber 6 flows into the inlet guide vane 301 to relieve pressure in advance, the control valve 8 relieves in advance, the response delay of the traditional mechanism is compensated, and the problem of temporary cavitation of the guide vane group 3 is solved.

[0025] Please combine Figures 4 to 8 The guide vane 301 is further provided with a guide plate 3012, which is used for guiding the backflow of the water body to avoid the backflow of the water body from colliding with the water flowing into the water inlet 201 to cause turbulence and affect the conveying efficiency. At the same time, when the guide plate 3012 cooperates with the check valve 7 in the water inlet 201, impurities in the fluid entering the pump body 2 can be filtered.

[0026] Please combine Figures 8 to 10 The guide plate 3012 is provided with two notches for avoiding the telescopic frame 9, so as to avoid interfering with the tilting movement of the telescopic frame 9.

[0027] Please combine Figure 10 The bottom of the valve body 802 is provided with a through groove 8021 for adapting the pressure relief pipe 10, so that the pressure relief pipe 10 does not limit its lifting opening, and at the same time, the pressure relief pipe 10 can ensure the stability of the bottom end.

[0028] Please combine Figure 3 The pump body 2 is provided with a pressure tank 11 on the water outlet 202, and the pressure tank 11 includes a tank body 1101 and a diaphragm 1102 arranged in the tank body 1101. The diaphragm 1102 and the tank body 1101 form an air chamber 1103 for filling nitrogen. The installation height of the pressure tank 11 is higher than the installation height of the check valve 7 in the water outlet 202. In this way, not only can the water hammer impact generated when the centrifugal pump is closed be absorbed, but also the water storage characteristics can release the stored water to supplement the system after the backflow of the fluctuating water body in the water supply is supplemented, preventing the pressure of the water supply system from dropping sharply.

[0029] Through the above technical solution, the pressure tank 11 realizes double functions by virtue of the special structure and installation height. During normal operation, the excess water flow enters the tank for storage. When the outlet pressure is weakened due to fluctuation of the water supply, the water flow in the tank is quickly released to supplement the pressure, avoiding the sharp drop of the pressure of the water supply system. When the centrifugal pump is closed, the diaphragm 1102 in the tank absorbs the water hammer energy through elastic deformation, buffers the pressure fluctuation, protects the centrifugal pump, valve and pipeline, prolongs the service life of the system, and reduces the maintenance cost.

[0030] The implementation principle of a permanent magnet variable frequency self-suction type multi-stage centrifugal pump in the embodiment of the application is as follows: After the permanent magnet variable frequency motor 1 is started, the output shaft drives the rotor 4 and the plurality of impellers 5 fixed on the rotor 4 to rotate synchronously. The fluid enters the pump body 2 from the water inlet 201, and under the guidance of the plurality of impellers 5, the fluid enters the pressure chamber 6 through the guide vane group 3. In this process, under the action of the centrifugal force generated by the rotation of the impeller 5, the fluid is gradually pressurized, and is discharged through the water outlet 202; At this time, the pressure chamber 6 formed between the guide vane group 3 and the pump body 2 maintains normal pressure, which overcomes the elastic force of the first spring 803 to make the valve body 802 of the control valve 8 tightly abut against the backflow port 3011 to thereby close the backflow port 3011 and avoid the backflow of the fluid in the pressure chamber 6. At the same time, the water flow pressure pushes the stop valve 702 of the check valve 7 in the water inlet port 201 and the water outlet port 202 respectively, overcomes the elastic force of the second spring 703, and makes the check valve 7 start to be in an open state to ensure that the fluid realizes normal one-way flow. In this process, under the condition that the pressure supply pressure of the centrifugal pump is sufficient and the flow at the outlet end of the water supply system is less than the supply amount of the centrifugal pump, part of the water flow enters the pressure tank 11 to be stored as a backup; When the water supply amount is insufficient, the pressure in the pressure chamber 6 is weakened, until the valve body 802 of the control valve 8 cannot be tightly abutted, so that the backflow port 3011 is opened, and the fluid in the pressure chamber 6 is shunted to the inlet guide vane 301 through the backflow port 3011, so as to maintain the flow in the centrifugal pump and ensure that the total output flow in the pump body 2 is always higher than the minimum continuous flow; However, the entire centrifugal pump is weakened by the pressure caused by the fluctuation of the water supply amount, and the sequence is the inlet guide vane 301, the impeller guide vane 302, the pressure chamber 6, and finally the water outlet port 202. When the pressure in the pressure chamber 6 is weakened, it means that cavitation has occurred in the guide vane group 3; When the water supply amount decreases or fluctuates, the stop valve 702 of the check valve 7 in the water inlet port 201 is moved back under the elastic force of the second spring 703. At the same time, the telescopic frame 9 is tilted to make the bottom end of the telescopic frame 9 rise and unblock the both ends of the pressure relief pipe 10. In this way, the fluid in the pressure chamber 6 can be discharged in advance through the pressure relief pipe 10 into the inlet guide vane 301 to complete the pressure relief, so that the control valve 8 is opened in advance to realize the backflow of the fluid, thereby solving the problem of short-term cavitation of the guide vane group 3 after the flow fluctuation; At the same time, the fluid stored in the pressure tank 11 can also supplement the pressure weakening of the water outlet port 202 caused by the backflow.

[0031] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application. Any non-essential changes and replacements made by those skilled in the art on the basis of the present application shall fall within the protection scope of the present application.

Claims

1. A permanent magnet variable frequency self-priming multistage centrifugal pump, comprising a permanent magnet variable frequency motor (1) and a pump body (2) having an inlet (201) and an outlet (202), wherein a guide vane assembly (3) consisting of an inlet guide vane (301) and multiple impeller guide vanes (302) is fixedly disposed within the pump body (2), wherein a rotor (4) fixedly connected to the output shaft of the permanent magnet variable frequency motor (1) is rotatably disposed within the guide vane assembly (3), and each of the multiple impeller guide vanes (302) is provided with an impeller (5) fixedly connected to the rotor (4), characterized in that: A pressure chamber (6) is formed between the guide vane assembly (3) and the pump body (2). A return port (3011) for connecting the pressure chamber (6) is provided on the inlet guide vane (301). A control valve (8) is provided in the return port (3011). The control valve (8) includes a stop block (801) provided on the inlet guide vane (301). A valve body (802) is slidably provided on the stop block (801). A first spring (803) with both ends abutting against the two is sleeved on the valve body (802). When the pump body (2) is unable to close the control valve (8) due to insufficient water supply, the pressure in the pressure chamber (6) weakens and cannot be tightly closed. The control valve (8) opens, allowing the fluid in the pressure chamber (6) to be diverted to the inlet guide vane (301) through the return port (3011), so that the pump body (2) maintains a total output flow rate higher than the minimum continuous flow rate.

2. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 1, characterized in that, Check valves (7) are installed in both the inlet (201) and outlet (202) of the pump body (2).

3. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 2, characterized in that, The check valve (7) includes a connecting ring (701), a plug valve (702) is slidably installed inside the connecting ring (701), and a second spring (703) is sleeved on the plug valve (702) with its two ends abutting against the two.

4. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 2, characterized in that, The return port (3011) is provided with a pressure relief pipe (10) that connects the pressure chamber (6) and the inlet guide vane (301). The return port (3011) is rotatably provided with a telescopic frame (9) for sealing both ends of the pressure relief pipe (10). The top of the telescopic frame (9) is rotatably connected to the check valve (7) in the inlet (201). This causes the water supply in the pump body (2) to decrease, which causes the valve (702) to move back, thereby tilting the telescopic frame (9) and raising the bottom end of the telescopic frame (9) to release the sealing of both ends of the pressure relief pipe (10) and thus complete the return of water in the pressure chamber (6) in advance.

5. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 1, characterized in that, The inlet guide vane (301) is also equipped with a guide plate (3012) to guide the return water body and avoid the return water body from colliding with the water body flowing into the inlet (201) and causing turbulence that affects the conveying efficiency.

6. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 5, characterized in that, The guide plate (3012) is provided with two notches for avoiding the telescopic frame (9) so as to avoid interfering with the tilting movement of the telescopic frame (9).

7. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 4, characterized in that, The bottom of the valve body (802) is provided with a through groove (8021) for adapting the pressure relief pipe (10), so that the pressure relief pipe (10) will not restrict its lifting and opening, and at the same time, the pressure relief pipe (10) can ensure the stability of its bottom end.

8. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 1, characterized in that, A pressure tank (11) is installed on the outlet (202) of the pump body (2). The installation height of the pressure tank (11) is higher than the installation height of the check valve (7) inside the outlet (202). This not only absorbs the water hammer impact generated when the centrifugal pump is shut down, but also allows the stored water to be released to replenish the system after the water supply fluctuates and the water flows back to replenish the inlet flow, thus preventing the water supply system pressure from dropping sharply.

9. The permanent magnet variable frequency self-priming multistage centrifugal pump as described in claim 8, characterized in that, The pressure vessel (11) includes a vessel body (1101) and a diaphragm (1102) disposed within the vessel body (1101), wherein a gas chamber (1103) for filling with nitrogen is formed between the diaphragm (1102) and the vessel body (1101).

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