阅读说明：本技术 一种多级离心泵 (Multistage centrifugal pump ) 是由 袁利华 潘丽杰 于 2021-01-23 设计创作，主要内容包括：本发明涉及一种多级离心泵,包括泵体、转轴、第一叶轮、第二叶轮、第三叶轮和切换机构；所述泵体内转动连接有转轴；所述转轴上从左到右依次固定连接有第一叶轮、第二叶轮和第三叶轮；所述第一叶轮左侧和泵体形成有第一吸水口,第一叶轮右侧和泵体形成有第一出水口；所述第二叶轮左侧和泵体形成有第二吸水口,第二叶轮右侧和泵体形成有第二出水口；所述第三叶轮左侧和泵体形成有第三吸水口,第三叶轮右侧和泵体形成有第三出水口；所述泵体左侧设有和第一吸水口连通的进口A；所述泵体右侧设有出口B；本发明通过设置切换机构,可根据实际使用工况自动调节叶轮级数,改变多级离心泵的扬程,降低能耗,节省了成本；通过机械传动改变有效工作的叶轮数量,切换简单,节约时间,并且工作稳定。(The invention relates to a multistage centrifugal pump, which comprises a pump body, a rotating shaft, a first impeller, a second impeller, a third impeller and a switching mechanism, wherein the rotating shaft is arranged on the pump body; a rotating shaft is rotationally connected in the pump body; a first impeller, a second impeller and a third impeller are fixedly connected to the rotating shaft from left to right in sequence; a first water suction port is formed on the left side of the first impeller and the pump body, and a first water outlet is formed on the right side of the first impeller and the pump body; a second water suction port is formed in the left side of the second impeller and the pump body, and a second water outlet is formed in the right side of the second impeller and the pump body; a third water suction port is formed on the left side of the third impeller and the pump body, and a third water outlet is formed on the right side of the third impeller and the pump body; an inlet A communicated with the first water suction port is formed in the left side of the pump body; an outlet B is formed in the right side of the pump body; by arranging the switching mechanism, the invention can automatically adjust the impeller stage number according to the actual use working condition, change the lift of the multistage centrifugal pump, reduce the energy consumption and save the cost; the number of the impellers which work effectively is changed through mechanical transmission, the switching is simple, the time is saved, and the work is stable.)

1. A multistage centrifugal pump characterized by: the multistage centrifugal pump comprises a pump body (1), a rotating shaft (2), a first impeller (3), a second impeller (4), a third impeller (5) and a switching mechanism (6); a rotating shaft (2) is rotatably connected in the pump body (1); a first impeller (3), a second impeller (4) and a third impeller (5) are fixedly connected to the rotating shaft (2) from left to right in sequence; a first water suction port (31) is formed on the left side of the first impeller (3) and the pump body (1), and a first water outlet (32) is formed on the right side of the first impeller (3) and the pump body (1); a second water suction port (41) is formed in the left side of the second impeller (4) and the pump body (1), and a second water outlet (42) is formed in the right side of the second impeller (4) and the pump body (1); a third water suction port (51) is formed in the left side of the third impeller (5) and the pump body (1), and a third water outlet (52) is formed in the right side of the third impeller (5) and the pump body (1); an inlet A communicated with the first water suction port (31) is formed in the left side of the pump body (1); an outlet B is formed in the right side of the pump body (1);

the switching mechanism (6) is used for changing the communication relation among the first water outlet (32), the second water suction port (41), the second water outlet (42), the third water suction port (51), the third water outlet (52) and the outlet B, and the switching mechanism (6) can be switched among a first working position, a second working position and a third working position;

when the switching mechanism (6) is in the first working position, the second water suction port (41) is communicated with the second water outlet (42), the third water suction port (51) is communicated with the third water outlet (32), the first water outlet (32) is communicated with the outlet B, and the liquid at the inlet A is conveyed to the outlet B through the rotation of the first impeller (3);

when the switching mechanism (6) is located at a second working position, the second water suction port (41) is communicated with the second water outlet (42), the first water outlet (32) is communicated with the third water suction port (51), the third water outlet (52) is communicated with the outlet B, the liquid at the inlet A is conveyed to the third water suction port (51) through the rotation of the first impeller (3), and the liquid at the third water suction port (51) is conveyed to the outlet B through the rotation of the third impeller (5);

when the switching mechanism (6) is in a third working position, the first water outlet (32) is communicated with the second water suction port (41), the second water outlet (42) is communicated with the third water suction port (51), and the third water outlet (52) is communicated with the outlet B; the liquid at the inlet A is conveyed to the second water suction port (42) through the rotation of the first impeller (3), the liquid at the second water suction port (41) is conveyed to the third water suction port (51) through the rotation of the second impeller (4), and the liquid at the third water suction port (51) is conveyed to the outlet B through the rotation of the third impeller (5).

2. The multistage centrifugal pump of claim 1, wherein: the switching mechanism (6) comprises a mounting plate (61), a left rotating body (62), a right rotating body (63) and a switching motor (64); the mounting plate (61) is fixedly connected to the upper end of the pump body (1); a main flow channel (611) used for communicating the first water outlet (32) with the outlet B is arranged in the mounting plate (61); the lower end of the mounting plate (61) is respectively and rotatably connected with a left rotating body (62) and a right rotating body (63), and the upper ends of the left rotating body (62) and the right rotating body (63) penetrate through the main flow channel (611); switching motor (64) fixed connection is in mounting panel (61) upper end, and switching motor (64) output shaft and left rotator (62) fixed connection.

3. The multistage centrifugal pump of claim 2, wherein: the left rotating body (62) comprises a first gear (621), a first cylinder (622) and a first mounting shaft (623); a first cylinder (622) is arranged at the upper end of the first gear (621); a first mounting shaft (623) rotatably connected with the mounting plate (61) is arranged at the upper end of the first cylinder (622); a first through hole (6221) is arranged on the first cylinder (622) in a penetrating way; a first U-shaped groove (6222) communicated with the first through hole (6221) is arranged on the cylindrical surface of the first cylinder (622); two penetrating second through holes (6211) are symmetrically arranged on the first gear (621) along the axis of the first through hole (6221); two second U-shaped grooves (6212) are symmetrically arranged on the lower end surface of the first gear (621); the two second U-shaped grooves (6212) are communicated through a first tooth inner flow passage (6213) arranged in the first gear (621).

4. The multistage centrifugal pump of claim 3, wherein: the right rotating body (63) includes a second gear (631), a second cylinder (632), and a second mounting shaft (633); a second cylinder (632) is arranged at the upper end of the second gear (631), and the second gear (631) is meshed with the first gear (621); a second mounting shaft (633) rotationally connected with the mounting plate (61) is arranged at the upper end of the second cylinder (632); a third through hole (6321) penetrating through the second cylinder (632) is formed in the second cylinder; the lower end of the second gear (631) is provided with two blind holes (6311) along the axial direction of the first through hole (6221); the two blind holes (6311) are communicated through a second in-gear flow passage (6312) arranged in the second gear (631); two third through U-shaped grooves (6313) are formed in the second gear (631).

5. Multistage centrifugal pump according to claim 4, wherein the primary channel (611) communicates with the first water outlet (32) through a first outlet channel (11); a second inlet flow passage (12) is arranged on the second water suction port (41); a second outlet flow channel (13) is arranged on the second water outlet (42); a third inlet flow passage (14) is arranged on the third water suction port (51); and a third outlet flow channel (15) is arranged on the third water outlet (52).

6. Multistage centrifugal pump according to claim 5, wherein when the switching mechanism (6) is in the first working position, the first through hole (6221) axis and the main flow channel (611) axis are parallel, the main flow channel (611) where the left rotary body (62) is located communicates through the first through hole (6221); the second inlet flow channel (12) and the second outlet flow channel (13) are respectively communicated with the second U-shaped groove (6212), and the second inlet flow channel (12) is communicated with the second outlet flow channel (13) to enable the second impeller (4) to be in an internal circulation state; the axis of the third through hole (6321) is parallel to the axis of the main flow channel (611), and the main flow channel (611) where the right rotating body (63) is located is communicated through the third through hole (6321); the third inlet flow channel (14) and the third outlet flow channel (15) are respectively communicated with the blind hole (6311), and the third inlet flow channel (14) is communicated with the third outlet flow channel (15) to enable the third impeller (5) to be in an internal circulation state; the liquid at the inlet A is conveyed to the outlet B through the first outlet flow passage (11) and the main flow passage (611) in sequence by the rotation of the first impeller (3).

7. The multistage centrifugal pump according to claim 6, wherein the switching mechanism (6) is in the second working position after the switching motor (64) rotates forward to drive the first gear (621) to rotate 45 degrees clockwise; at the moment, the main flow passage (611) where the left rotating body (62) is located is communicated with the first U-shaped groove (6222), and the first U-shaped groove (6222) enables the main flow passage (611) to continuously keep a communicated state; the second inlet flow channel (12) and the second outlet flow channel (13) are respectively communicated with the second U-shaped groove (6212), and the second impeller (4) is in an internal circulation state; the main flow passage (611) where the right rotating body (63) is located is partitioned by a second cylinder (632); the third inlet runner (14) and the third outlet runner (15) are respectively communicated with the main runner (611) through a third U-shaped groove (6313); the liquid at the inlet A is conveyed to the third water sucking port (51) through the first outlet flow channel (11), the main flow channel (611) and the third inlet flow channel (14) in sequence by the rotation of the first impeller (3), and the liquid at the third water sucking port (51) is conveyed to the outlet B through the third outlet flow channel (15) and the main flow channel (611) in sequence by the rotation of the third impeller (5).

8. The multistage centrifugal pump according to claim 7, wherein the switching mechanism (6) is in a third working position after the switching motor (64) continues to rotate forward to drive the first gear (621) to rotate 45 degrees in the clockwise direction; at the moment, the main flow passage (611) where the left rotating body (62) is located is blocked by the first cylinder (622); the second inlet flow channel (12) and the second outlet flow channel (13) are respectively communicated with the second through hole (6211); the main flow passage (611) where the right rotating body (63) is located is partitioned by a second cylinder (632); the third inlet runner (14) and the third outlet runner (15) are respectively communicated with the main runner (611) through a third U-shaped groove (6313); the liquid at the inlet A is conveyed to the second water sucking port (41) through the first outlet flow channel (11), the main flow channel (611) and the second inlet flow channel (12) in sequence by the rotation of the first impeller (3), the liquid at the second water sucking port (41) is conveyed to the third water sucking port (51) through the second outlet flow channel (13), the main flow channel (611) and the third inlet flow channel (14) in sequence by the rotation of the second impeller (4), and the liquid at the third water sucking port (51) is conveyed to the outlet B through the third outlet flow channel (15) and the main flow channel (611) by the rotation of the third impeller (5).

Technical Field

The invention belongs to the technical field of fluid pumps, and particularly relates to a multistage centrifugal pump.

Background

The centrifugal pump works by utilizing the rotation of an impeller to enable liquid to generate centrifugal motion, and the working principle is as follows: after the liquid enters the pump shell, the flow velocity of the liquid is gradually reduced due to the gradual expansion of the flow channel in the volute-shaped pump shell, a part of kinetic energy is converted into static pressure energy, and then the liquid flows out along the discharge port at higher pressure. Meanwhile, a certain vacuum is formed at the center of the impeller due to the fact that liquid is thrown out, and the pressure at the liquid level is higher than that at the center of the impeller. Therefore, the liquid in the suction pipeline enters the pump under the action of pressure difference, the impeller rotates continuously, and the liquid is sucked and pressed out continuously.

The problem that a large horse pulls a trolley in actual work of the multi-stage centrifugal pump is generally solved, and the problem is caused by unreasonable flow and lift of selected equipment or changed process conditions during design and model selection, so that the additional allowance of the lift of the centrifugal pump is overlarge, the operation efficiency is low, and the power consumption is large. Technical reconstruction is generally performed by reducing the number of impellers, but the method is complex to disassemble and assemble, takes long time, and the reconstructed centrifugal pump is easy to work unstably.

Disclosure of Invention

In order to solve the above problems, the present invention provides a multistage centrifugal pump.

In order to achieve the above object, the present invention provides the following technical solution, including a pump body, a rotating shaft, a first impeller, a second impeller, a third impeller and a switching mechanism; a rotating shaft is rotationally connected in the pump body; a first impeller, a second impeller and a third impeller are fixedly connected to the rotating shaft from left to right in sequence; a first water suction port is formed on the left side of the first impeller and the pump body, and a first water outlet is formed on the right side of the first impeller and the pump body; a second water suction port is formed in the left side of the second impeller and the pump body, and a second water outlet is formed in the right side of the second impeller and the pump body; a third water suction port is formed on the left side of the third impeller and the pump body, and a third water outlet is formed on the right side of the third impeller and the pump body; an inlet A communicated with the first water suction port is formed in the left side of the pump body; an outlet B is formed in the right side of the pump body.

The switching mechanism is used for changing the communication relation among the first water outlet, the second water sucking port, the second water outlet, the third water sucking port, the third water outlet and the outlet B, and can be switched among a first working position, a second working position and a third working position.

When the switching mechanism is located at the first working position, the second water suction port is communicated with the second water outlet, the third water suction port is communicated with the third water outlet, the first water outlet is communicated with the outlet B, and the liquid at the inlet A is conveyed to the outlet B through the rotation of the first impeller.

When the switching mechanism is located at the second working position, the second water suction port is communicated with the second water outlet, the first water outlet is communicated with the third water suction port, the third water outlet is communicated with the outlet B, the liquid at the inlet A is conveyed to the third water suction port through the rotation of the first impeller, and the liquid at the third water suction port is conveyed to the outlet B through the rotation of the third impeller.

When the switching mechanism is positioned at a third working position, the first water outlet is communicated with the second water suction port, the second water outlet is communicated with the third water suction port, and the third water outlet is communicated with the outlet B; the liquid in the inlet A is conveyed to the second water suction port through the rotation of the first impeller, the liquid in the second water suction port is conveyed to the third water suction port through the rotation of the second impeller, and the liquid in the third water suction port is conveyed to the outlet B through the rotation of the third impeller.

Preferably, the switching mechanism includes a mounting plate, a left rotating body, a right rotating body, and a switching motor; the mounting plate is fixedly connected to the upper end of the pump body; a main runner for communicating the first water outlet with the outlet B is arranged in the mounting plate; the lower end of the mounting plate is respectively and rotatably connected with a left rotating body and a right rotating body, and the upper ends of the left rotating body and the right rotating body penetrate through the main runner; the switching motor is fixedly connected to the upper end of the mounting plate, and an output shaft of the switching motor is fixedly connected with the left rotating body.

Preferably, the left rotating body includes a first gear, a first cylinder, and a first mounting shaft; a first cylinder is arranged at the upper end of the first gear; the upper end of the first cylinder is provided with a first mounting shaft which is rotationally connected with the mounting plate; a first through hole is formed in the first cylinder in a penetrating mode; a first U-shaped groove communicated with the first through hole is formed in the cylindrical surface of the first cylinder; two penetrating second through holes are symmetrically formed in the first gear along the axis of the first through hole; two second U-shaped grooves are symmetrically formed in the lower end face of the first gear; and the two second U-shaped grooves are communicated through a first tooth inner runner arranged in the first gear.

Preferably, the right rotating body includes a second gear, a second cylinder, and a second mounting shaft; a second cylinder is arranged at the upper end of the second gear, and the second gear is meshed with the first gear; a second mounting shaft rotatably connected with the mounting plate is arranged at the upper end of the second cylinder; a third through hole is formed in the second cylinder in a penetrating mode; the lower end of the second gear is provided with two blind holes along the axial direction of the first through hole; the two blind holes are communicated through a second in-tooth flow passage arranged in the second gear; and two third through U-shaped grooves are formed in the second gear.

Preferably, the main flow channel is communicated with the first water outlet through a first outlet flow channel; a second inlet flow passage is arranged on the second water suction port; a second outlet flow channel is arranged on the second water outlet; a third inlet flow passage is arranged on the third water suction port; and a third outlet flow channel is arranged on the third water outlet.

Preferably, when the switching mechanism is in the first working position, the axis of the first through hole is parallel to the axis of the main flow passage, and the main flow passage where the left rotary body is located is communicated through the first through hole; the second inlet runner and the second outlet runner are respectively communicated with the second U-shaped groove, and the second inlet runner and the second outlet runner are communicated to enable the second impeller to be in an internal circulation state; the axis of the third through hole is parallel to the axis of the main runner, and the main runner where the right rotating body is located is communicated through the third through hole; the third inlet flow channel and the third outlet flow channel are respectively communicated with the blind holes, and the third inlet flow channel and the third outlet flow channel are communicated to enable the third impeller to be in an internal circulation state; the liquid at the inlet A is conveyed to the outlet B through the first outlet flow channel and the main flow channel in sequence by the rotation of the first impeller.

Preferably, after the switching motor rotates clockwise to drive the first gear to rotate clockwise, the switching mechanism is in a second working position; at the moment, the main flow channel where the left rotator is located is communicated with the first U-shaped groove, and the first U-shaped groove enables the main flow channel to continuously keep a communicated state; the second inlet flow channel and the second outlet flow channel are respectively communicated with the second U-shaped groove, and the second impeller is in an internal circulation state; the main flow passage where the right rotating body is located is partitioned by a second cylinder; the third inlet runner and the third outlet runner are respectively communicated with the main runner through a third U-shaped groove; the liquid at the inlet A is conveyed to the third water sucking port through the first outlet flow channel, the main flow channel and the third inlet flow channel in sequence by the rotation of the first impeller, and the liquid at the third water sucking port is conveyed to the outlet B through the third outlet flow channel and the main flow channel in sequence by the rotation of the third impeller.

Preferably, after the switching motor continues to rotate forward to drive the first gear to rotate clockwise, the switching mechanism is in a third working position; at the moment, the main flow passage where the left rotator is located is partitioned by the first cylinder; the second inlet flow channel and the second outlet flow channel are respectively communicated with the second through hole; the main flow passage where the right rotating body is located is partitioned by a second cylinder; the third inlet runner and the third outlet runner are respectively communicated with the main runner through a third U-shaped groove; the liquid at the inlet A is conveyed to the second water suction port through the first outlet flow channel, the main flow channel and the second inlet flow channel in sequence by the rotation of the first impeller, the liquid at the second water suction port is conveyed to the third water suction port through the second outlet flow channel, the main flow channel and the third inlet flow channel in sequence by the rotation of the second impeller, and the liquid at the third water suction port is conveyed to the outlet B through the third outlet flow channel and the main flow channel by the rotation of the third impeller.

Compared with the prior art, the invention has the advantages that:

by arranging the switching mechanism, the invention can automatically adjust the impeller stage number according to the actual use working condition, change the lift of the multistage centrifugal pump, reduce the energy consumption and save the cost; the number of the impellers which work effectively is changed through mechanical transmission, the switching is simple, the time is saved, and the work is stable.

Drawings

FIG. 1 is an overall cross-sectional view of the present invention;

FIG. 2 is a sectional view taken along line G-G of FIG. 1 in accordance with the present invention;

FIG. 3 is a sectional view taken along line H-H of FIG. 1 in accordance with the present invention;

FIG. 4 is a schematic view of a second operating position of the switching mechanism of the present invention;

FIG. 5 is a schematic view of another angle of view of the switching mechanism in the second operating position according to the present invention;

FIG. 6 is a schematic view of a third operating position of the switching mechanism of the present invention;

FIG. 7 is a schematic view of another operating position of the switching mechanism of the present invention;

FIG. 8 is a three-dimensional structure view of the left rotating body according to the present invention;

FIG. 9 is a three-dimensional block diagram of another perspective of the left rotary body of the present invention;

FIG. 10 is a three-dimensional view of the right rotating body according to the present invention;

FIG. 11 is a three-dimensional block diagram of another perspective of the right rotator according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in fig. 1-11, is a preferred embodiment of the present invention.

A multi-stage centrifugal pump comprises a pump body 1, a rotating shaft 2, a first impeller 3, a second impeller 4, a third impeller 5 and a switching mechanism 6; a rotating shaft 2 is rotatably connected in the pump body 1; a first impeller 3, a second impeller 4 and a third impeller 5 are fixedly connected to the rotating shaft 2 from left to right in sequence; a first water suction port 31 is formed on the left side of the first impeller 3 and the pump body 1, and a first water outlet port 32 is formed on the right side of the first impeller 3 and the pump body 1; a second water suction port 41 is formed on the left side of the second impeller 4 and the pump body 1, and a second water outlet 42 is formed on the right side of the second impeller 4 and the pump body 1; a third water suction port 51 is formed on the left side of the third impeller 5 and the pump body 1, and a third water outlet 52 is formed on the right side of the third impeller 5 and the pump body 1; an inlet A communicated with the first water suction port 31 is formed in the left side of the pump body 1; an outlet B is formed in the right side of the pump body 1.

The switching mechanism 6 is used for changing the communication relationship among the first water outlet 32, the second water suction port 41, the second water outlet 42, the third water suction port 51, the third water outlet 52 and the outlet B, and the switching mechanism 6 can be switched among a first working position, a second working position and a third working position.

When the switching mechanism 6 is in the first working position, the second water suction port 41 is communicated with the second water outlet 42, the third water suction port 51 is communicated with the third water outlet 32, the first water outlet 32 is communicated with the outlet B, and the liquid at the inlet a is conveyed to the outlet B through the rotation of the first impeller 3.

When the switching mechanism 6 is in the second working position, the second water suction port 41 is communicated with the second water outlet 42, the first water outlet 32 is communicated with the third water suction port 51, the third water outlet 52 is communicated with the outlet B, the liquid at the inlet a is conveyed to the third water suction port 51 by the rotation of the first impeller 3, and the liquid at the third water suction port 51 is conveyed to the outlet B by the rotation of the third impeller 5.

When the switching mechanism 6 is in the third working position, the first water outlet 32 is communicated with the second water suction port 41, the second water outlet 42 is communicated with the third water suction port 51, and the third water outlet 52 is communicated with the outlet B; the liquid at the inlet A is conveyed to the second water suction port 42 by the rotation of the first impeller 3, the liquid at the second water suction port 41 is conveyed to the third water suction port 51 by the rotation of the second impeller 4, and the liquid at the third water suction port 51 is conveyed to the outlet B by the rotation of the third impeller 5.

The switching mechanism 6 includes a mounting plate 61, a left rotating body 62, a right rotating body 63, and a switching motor 64; the mounting plate 61 is fixedly connected to the upper end of the pump body 1; a main flow channel 611 used for communicating the first water outlet 32 with the outlet B is arranged in the mounting plate 61; the lower end of the mounting plate 61 is rotatably connected with a left rotating body 62 and a right rotating body 63 respectively, and the upper ends of the left rotating body 62 and the right rotating body 63 both pass through the main flow channel 611; the switching motor 64 is fixedly connected to the upper end of the mounting plate 61, and the output shaft of the switching motor 64 is fixedly connected with the left rotator 62.

The left rotating body 62 includes a first gear 621, a first cylinder 622, and a first mounting shaft 623; a first cylinder 622 is arranged at the upper end of the first gear 621; a first mounting shaft 623 rotatably connected with the mounting plate 61 is arranged at the upper end of the first cylinder 622; a first through hole 6221 is formed in the first cylinder 622; a first U-shaped groove 6222 communicated with the first through hole 6221 is arranged on the cylindrical surface of the first cylinder 622; two penetrating second through holes 6211 are symmetrically arranged on the first gear 621 along the axis of the first through hole 6221; two second U-shaped grooves 6212 are symmetrically arranged on the lower end surface of the first gear 621; the two second U-shaped grooves 6212 are communicated with each other through a first tooth inner flow passage 6213 provided in the first gear 621.

The right rotating body 63 includes a second gear 631, a second cylinder 632, and a second mounting shaft 633; the second cylinder 632 is arranged at the upper end of the second gear 631, and the second gear 631 is engaged with the first gear 621; a second mounting shaft 633 rotatably connected with the mounting plate 61 is arranged at the upper end of the second cylinder 632; a third through hole 6321 is formed through the second cylinder 632; the lower end of the second gear 631 is provided with two blind holes 6311 along the axial direction of the first through hole 6221; the two blind holes 6311 are communicated through a second in-tooth flow passage 6312 provided in the second gear 631; two third through U-shaped grooves 6313 are disposed on the second gear 631.

The main flow passage 611 is communicated with the first water outlet 32 through the first outlet flow passage 11; a second inlet flow passage 12 is arranged on the second water suction port 41; a second outlet flow channel 13 is arranged on the second water outlet 42; a third inlet runner 14 is arranged on the third water suction port 51; a third outlet flow passage 15 is arranged on the third water outlet 52.

When the switching mechanism 6 is in the first working position (see fig. 1, 2 and 3), the axis of the first through hole 6221 is parallel to the axis of the main flow passage 611, and the main flow passage 611 where the left rotary body 62 is located is communicated through the first through hole 6221; the second inlet flow passage 12 and the second outlet flow passage 13 are respectively communicated with a second U-shaped groove 6212, and the second inlet flow passage 12 is communicated with the second outlet flow passage 13 to enable the second impeller 4 to be in an internal circulation state; the axis of the third through hole 6321 is parallel to the axis of the main channel 611, and the main channel 611 where the right rotating body 63 is located is communicated with the third through hole 6321; the third inlet flow channel 14 and the third outlet flow channel 15 are respectively communicated with the blind hole 6311, and the third inlet flow channel 14 and the third outlet flow channel 15 are communicated to enable the third impeller 5 to be in an internal circulation state; the liquid of the inlet a is delivered to the outlet B through the first outlet flow channel 11 and the main flow channel 611 in order by the rotation of the first impeller 3.

After the switching motor 64 rotates forward to drive the first gear 621 to rotate 45 degrees clockwise, the switching mechanism 6 is in a second working position (fig. 4 and 5); at this time, the main flow passage 611 where the left rotating body 62 is located is communicated with the first U-shaped groove 6222, and the first U-shaped groove 6222 enables the main flow passage 611 to continuously maintain a communicated state; the second inlet flow passage 12 and the second outlet flow passage 13 are respectively communicated with the second U-shaped groove 6212, and the second impeller 4 is in an internal circulation state; the main flow passage 611 where the right rotator 63 is located is blocked by the second cylinder 632; the third inlet runner 14 and the third outlet runner 15 are respectively communicated with the main runner 611 through a third U-shaped groove 6313; the liquid at the inlet a is transported to the third water suction port 51 through the first outlet flow passage 11, the main flow passage 611 and the third inlet flow passage 14 in sequence by the rotation of the first impeller 3, and the liquid at the third water suction port 51 is transported to the outlet B through the third outlet flow passage 15 and the main flow passage 611 in sequence by the rotation of the third impeller 5.

After the switching motor 64 continues to rotate forward to drive the first gear 621 to rotate 45 degrees clockwise, the switching mechanism 6 is in a third working position (see fig. 6 and 7); at this time, the main flow channel 611 where the left rotating body 62 is located is blocked by the first cylinder 622; the second inlet flow passage 12 and the second outlet flow passage 13 are respectively communicated with the second through hole 6211; the main flow passage 611 where the right rotator 63 is located is blocked by the second cylinder 632; the third inlet runner 14 and the third outlet runner 15 are respectively communicated with the main runner 611 through a third U-shaped groove 6313; the rotation of the first impeller 3 conveys the liquid at the inlet a to the second water suction port 41 through the first outlet flow passage 11, the main flow passage 611 and the second inlet flow passage 12 in sequence, the rotation of the second impeller 4 conveys the liquid at the second water suction port 41 to the third water suction port 51 through the second outlet flow passage 13, the main flow passage 611 and the third inlet flow passage 14 in sequence, and the rotation of the third impeller 5 conveys the liquid at the third water suction port 51 to the outlet B through the third outlet flow passage 15 and the main flow passage 611.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.