Liquid delivery pump

Abstract

The utility model provides a liquid delivery pump, which comprises a first shell, a second shell and a third shell, the second shell comprises a pump inlet, a pump outlet and a pump cavity which is in fluid communication with the pump inlet and the pump outlet; the impeller assembly comprises a centrifugal impeller and an axial flow impeller, and at least part of the impeller assembly is arranged in the pump cavity of the second shell; the impeller assembly comprises a hollow body part, the hollow body part comprises a first end adjacent to the pump inlet and a second end which is far away from the pump inlet and is opposite to the first end, the axial flow impeller is formed at the first end of the hollow body part, and the centrifugal impeller is formed at the second end of the hollow body part; and the driving assembly is at least partially arranged in the containing cavity of the first shell, and the driving assembly is configured to drive the impeller assembly to operate. The axial flow pump is additionally arranged at the front end of the centrifugal pump, the air binding problem of the centrifugal pump is solved, and the reliability of the liquid conveying pump is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to water pump technical field, fluid machinery field, especially a kind of liquid delivery pump. BACKGROUND

[0002] Liquid delivery pump is a kind of equipment that converts mechanical energy into liquid kinetic energy, and is widely used in farmland irrigation, industrial production, urban water supply and sewage treatment and other fields. Among various types of liquid delivery pumps, vertical submersible centrifugal pump is widely used in various industrial fields due to its advantages of high efficiency, energy saving, small floor space and the like. However, during use of centrifugal pump, air binding problem is often encountered, i.e. pump cavity is filled with air. Since air has low density, centrifugal force generated after pump starts rotating is small, and low pressure formed in impeller center area is insufficient to suck liquid into pump cavity, so liquid delivery pump cannot pump liquid normally.

[0003] Existing technologies mainly set water guide pipe in pump cavity to guide liquid into pump cavity to discharge air. In addition, some technical solutions set nozzle in pump cavity to spray liquid to form negative pressure to discharge air from pump cavity. Although these methods can solve air binding problem to some extent, they need additional water guide pipe or nozzle, which increases complexity and cost of equipment. Moreover, these methods can only temporarily solve air binding problem, and if air enters pump cavity again, water pump still cannot work normally.

[0004] Therefore, a method and device for solving air binding problem of centrifugal pump without additional water guide pipe or nozzle are urgently needed. UTILITY MODEL CONTENT

[0005] To solve the above problems and defects in existing technologies, the purpose of the utility model is to provide a method and device for solving air binding problem of centrifugal pump without additional water guide pipe or nozzle.

[0006] Based on this, according to one embodiment of the utility model, a liquid delivery pump is provided, which comprises: a first shell defining a containing cavity; a second shell comprising a pump inlet, a pump outlet and a pump cavity in fluid communication with the pump inlet and the pump outlet; an impeller assembly comprising a centrifugal impeller and an axial flow impeller, which is at least partially arranged in the pump cavity of the second shell; the impeller assembly comprises a hollow body portion, the hollow body portion comprises a first end adjacent to the pump inlet and a second end opposite to the first end and away from the pump inlet, the axial flow impeller is formed at the first end of the hollow body portion, and the centrifugal impeller is formed at the second end of the hollow body portion; a driving assembly at least partially arranged in the containing cavity of the first shell, the driving assembly is configured to drive the impeller assembly to operate.

[0007] In one embodiment, the drive assembly is configured to drive the axial flow impeller to rotate to draw liquid from the pump inlet into the pump cavity, and to drive the centrifugal impeller to rotate to deliver the liquid drawn by the axial flow impeller to the pump outlet via the pump cavity.

[0008] In one embodiment, the impeller assembly is integrally formed, and the axial flow impeller and the centrifugal impeller are coaxially rotatable.

[0009] In one embodiment, the second end of the hollow body portion includes a disc-shaped portion extending radially outward, the centrifugal impeller includes a plurality of centrifugal blades circumferentially spaced apart on the disc-shaped portion, and the axial flow impeller includes a plurality of axial flow blades circumferentially spaced apart on an inner wall of the first end.

[0010] In one embodiment, the drive assembly includes a direct current brushless motor.

[0011] In one embodiment, the receiving cavity of the first housing includes a first sub-cavity and a second sub-cavity, a stator of the direct current brushless motor is disposed in the first sub-cavity, and a rotor of the direct current brushless motor is disposed in the second sub-cavity and coupled with the impeller assembly.

[0012] In one embodiment, the second housing includes an outward protrusion adjacent to the axial flow impeller, and the outward protrusion is laterally formed with a through hole to define the pump inlet.

[0013] In one embodiment, a top portion of the outward protrusion is formed with a cylinder inserted into the hollow body portion from the first end.

[0014] According to another exemplary embodiment of the present application, a liquid delivery pump is provided, including: a first housing defining a receiving cavity; a second housing including a pump inlet, a pump outlet, and a pump cavity fluidically connecting the pump inlet and the pump outlet, wherein the pump inlet is formed around by a nozzle portion extending outwardly from the second housing, and the nozzle portion is formed with a plurality of grooves distributed circumferentially; an impeller assembly at least partially disposed in the pump cavity of the second housing, the impeller assembly including a centrifugal impeller and an axial flow impeller coaxially connected in series with the centrifugal impeller, the axial flow impeller being arranged adjacent to the nozzle portion of the second housing; and a drive assembly at least partially disposed in the receiving cavity of the first housing, the drive assembly being configured to drive the impeller assembly to operate.

[0015] In one embodiment, the drive assembly is configured to drive the axial flow impeller to rotate to draw liquid from the pump inlet into the pump cavity, and to drive the centrifugal impeller to rotate to deliver the liquid drawn by the axial flow impeller to the pump outlet via the pump cavity.

[0016] In another embodiment, the drive assembly includes a drive shaft, and the centrifugal impeller and the axial impeller are sleeved on the drive shaft.

[0017] In another embodiment, the drive assembly includes a direct current brushless motor.

[0018] In the foregoing various exemplary embodiments of the present application, compared with the prior art, the present application can solve the gas binding problem without increasing additional water pipes or nozzles, and also improves the practicability and economy of the liquid delivery pump. By additionally providing an axial flow pump at the front end of the centrifugal pump, the air inside the pump cavity and the impeller is forcibly discharged before the liquid delivery pump is started, avoiding the gas binding condition of the centrifugal pump, not only improving the reliability and stability of the liquid delivery pump, but also prolonging the service life of the liquid delivery pump and reducing the maintenance cost. Secondly, the same speed is used to drive the centrifugal pump and the axial flow pump in the technical solution, which simplifies the design of the equipment and reduces the complexity and cost of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0019] The features, advantages, and other aspects of the embodiments of the present application will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which a number of embodiments of the present application are illustrated, by way of example, and not limitation, in the drawings:

[0020] Figure 1 is a sectional view of the liquid delivery pump of one embodiment of the present application;

[0021] Figure 2 is a bottom view of the liquid delivery pump of one embodiment of the present application;

[0022] Figure 3 is a schematic view of the rotor-impeller integrated type of one embodiment of the present application;

[0023] Figure 4 is a schematic view of the centrifugal impeller of one embodiment of the present application;

[0024] Figure 5 is another perspective view of the rotor-impeller integrated type of one embodiment of the present application;

[0025] Figure 6 is a bottom perspective view of the rotor-impeller integrated type of one embodiment of the present application;

[0026] Figure 7 is an exploded schematic view of the liquid delivery pump of one embodiment of the present application;

[0027] Figure 8 is a sectional view of the liquid delivery pump of another embodiment of the present application;

[0028] Figure 9 a bottom view of the liquid delivery pump of another embodiment of the present application;

[0029] Figure 10 a bottom view of the liquid delivery pump of another embodiment of the present application; DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be further described in detail below with reference to the embodiments and the accompanying drawings. In the description, the same or similar reference signs indicate the same or similar components. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general inventive concept of the present application, and should not be construed as a limitation of the present application.

[0031] The terms "comprise", "include" and similar terms used herein are understood in an open sense, i.e. "comprising / include, but not limited to", indicating that other content can also be included. The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment", and so on.

[0032] The prior art mainly solves the gas lock problem of the centrifugal pump by setting a water guide pipe or a nozzle in the pump cavity to discharge air from the pump cavity. However, if air enters the pump cavity again, the water pump cannot work normally. Therefore, the existing technology not only increases the complexity and cost of the liquid delivery pump, but also has great limitations.

[0033] The liquid delivery pump according to the embodiments of the present application can discharge air in the entire pump cavity by setting a axial flow at the front end of the centrifugal pump, and the self-suction capacity of the axial flow pump can generate negative pressure, thereby effectively solving the gas lock problem. In the following, the liquid delivery pump of each embodiment of the present application will be described with reference to the accompanying drawings.

[0034] Figure 1 a cross-sectional view of the liquid delivery pump according to one embodiment of the present application is shown; Figure 2 a bottom view of the liquid delivery pump according to one embodiment of the present application is shown. In combination with reference to Figure 1 and Figure 2 The exemplary liquid delivery pump 10 includes a first housing 11, a second housing 12, an impeller assembly 13, and a drive assembly 16. The second housing 12 includes a pump inlet 121, a pump outlet 122, and a pump cavity 123 fluidly connecting the pump inlet 121 and the pump outlet 122.

[0035] The impeller assembly 13 is at least partially disposed within a pump cavity 123 of the second housing 12. The impeller assembly 13 includes a centrifugal impeller 14 and an axial impeller 15. The axial impeller 15 can be arranged adjacent to a pump inlet 121 of the second housing 12.

[0036] The impeller assembly 13 can take on a variety of forms. In one embodiment, the impeller assembly 13 can include a hollow body 131. The hollow body 131 can include a first end 132a adjacent to the pump inlet 121 and a second end 132b opposite the first end 132a and distal from the pump inlet 121. The axial impeller 15 can be formed at the first end 132a of the hollow body 131 and the centrifugal impeller 14 can be formed at the second end 132b of the hollow body 131. In one embodiment, the second end 132b of the hollow body 131 can be arranged adjacent to the pump outlet 122.

[0037] The drive assembly 16 is at least partially disposed within the receiving cavity 111 of the first housing 11 to drive the impeller assembly 13 to operate. In one embodiment, the drive assembly 16 can drive the axial impeller 15 to rotate to draw liquid from outside the liquid transfer pump 10 into the pump inlet 121 and drive the centrifugal impeller 14 to rotate to deliver the liquid drawn by the axial impeller 15 through the pump cavity 123 to the pump outlet 122. When the drive assembly 16 drives the axial impeller 15 to rotate, the axial impeller 15 draws liquid from outside the liquid transfer pump 10 into the pump inlet 121 by the axial force generated by the rotation of the axial impeller 15. Since the axial impeller 15 generates self-suction force when it rotates, a negative pressure can be formed at the pump inlet 121 to help the liquid fill the pump cavity 123 quickly, so that the air originally present in the pump cavity 123 is pushed by the liquid flow to the pump outlet 122 and discharged, ensuring that no air remains in the pump cavity 123. At the same time, the drive assembly 16 drives the centrifugal impeller 14 to rotate. After the air in the pump cavity 123 is removed and the pump cavity 123 is filled with liquid under the rotation of the axial impeller 15, the centrifugal force generated by the rotation of the centrifugal impeller 14 further pressurizes the liquid in the pump cavity 123 and pushes the liquid to the pump outlet 122 for delivery, and finally the liquid is discharged from the pump outlet 122.

[0038] In one embodiment, the axial impeller 15 and the centrifugal impeller 14 can be arranged to rotate coaxially. Coaxial rotation can ensure that the centrifugal impeller 14 and the axial impeller 15 have the same rotational speed, simplifying the design of the device while reducing the complexity and cost of the device.

[0039] In one embodiment, the impeller assembly 13 can be integrally formed. However, in other embodiments, the axial impeller 15 and the centrifugal impeller 14 in the impeller assembly 13 can also be two separate components.

[0040] In one embodiment, the second housing 12 further comprises an outward protrusion 124 adjacent to the axial impeller 15. The side of the outward protrusion 124 can be formed with a plurality of evenly distributed through holes 125 (e.g. four through holes) defining a pump inlet 121. It can be appreciated that the number of the through holes 125 is not limited to four, which can be set according to actual needs. A cylinder 126 is further formed on the top of the outward protrusion 124 and inserted into the hollow body 131 from the first end 132a, so that the liquid entering the pump cavity 123 via the through holes 125 flows axially upward along the cylinder 126.

[0041] In one embodiment, the driving assembly 16 can be a direct current brushless motor. The direct current brushless motor generally has the advantages of reduced wear and tear due to the absence of carbon brushes, improved motor efficiency and reliability, and low noise. However, in other embodiments, the driving assembly 16 can also be other types of motors or structures having driving functions.

[0042] In one embodiment, the accommodating cavity 111 defined by the first housing 11 can further comprise a first sub-cavity 111a and a second sub-cavity 111b. The stator 161 of the direct current brushless motor can be arranged in the first sub-cavity 111a. The rotor 162 of the direct current brushless motor can be arranged in the second sub-cavity 111b and coupled with the impeller assembly 13 to drive the centrifugal impeller 14 and the axial impeller 15 in the impeller assembly 13 to rotate.

[0043] The stator 161 can be made of, for example, silicon steel sheets laminated together and having coils wound thereon. The current supplied by a motor driver (not shown) is applied to the coils to start the driving assembly 16 and cause the stator 161 to generate a rotating magnetic field. The rotor 162 can be made of, for example, a ring-shaped plastic outer cover with a ring-shaped magnet or other materials such as copper or aluminum having good electrical conductivity. The rotor 162 is cut by the magnetic lines of force in the rotating magnetic field generated by the stator 161, thereby generating electric current. These electric currents interact with the magnetic field generated by the stator 161 to form an electromagnetic torque, which drives the rotor 162 to continuously rotate.

[0044] Figure 3 A schematic view of a rotor-impeller integrated type is shown according to one embodiment of the present application; Figure 4 A schematic view of a centrifugal impeller is shown according to one embodiment of the present application. In combination with Figure 3 and Figure 4, the centrifugal impeller 14 is coupled with the rotor 162 and forms an integrated structure of the rotor 162 and the impeller assembly 13. In an embodiment, the second end 132b of the hollow body 131 of the impeller assembly 13 can further include a disc-shaped portion 133 extending radially outward. The centrifugal impeller 14 can include a plurality of centrifugal blades 141 arranged axially spaced apart on the disc-shaped portion 133. The number of the centrifugal blades 141 can be two or more and arranged centrally symmetrically on the disc-shaped portion 133. The inner wall of the hollow portion 1621 of the rotor 162 can further include a bearing 18 for supporting the rotation of the rotor 162 and can effectively reduce the friction generated during the rotation of the rotor 162, ensure the rotation accuracy thereof, and reduce the maintenance cost thereof in subsequent use. The bearing 18 can be made of, for example, graphite material or other materials having good self-lubricating property, chemical stability and high temperature resistance.

[0045] Figure 5 Fig. 4 shows another perspective view of the rotor-impeller integrated structure according to an embodiment of the present application; Figure 6 Fig. 5 shows a bottom perspective view of the rotor-impeller integrated structure according to an embodiment of the present application. For reference, Figure 5 and Figure 6 The axial flow impeller 15 includes a plurality of axial flow blades 151 arranged axially spaced apart on the inner wall of the first end 132a of the hollow body 131. The number of the axial flow blades 151 can be two or more, which can be set according to actual needs. For example, when the head of the axial flow pump formed by the axial flow impeller 15 is not higher than two meters, the number of the axial flow blades 151 can be two to four; when the head thereof is higher than two meters, the number of the axial flow blades 151 can be five to ten.

[0046] The centrifugal pump formed by the centrifugal impeller 14 generally has the characteristics of low flow and high head, while the axial flow pump formed by the axial flow impeller 15 generally has the characteristics of high flow and low head. Therefore, when the centrifugal impeller 14 and the axial flow impeller 15 rotate coaxially, if the ratio of the height H of the axial flow blades 151 to the diameter D of the axial flow impeller 15 is not properly set, it will have a negative impact on the performance of the centrifugal pump. Possible negative impacts include, for example, a decrease in the head and flow of the centrifugal pump, an increase in noise, and an increase in the power of the entire liquid delivery pump system. Therefore, according to experimental data analysis, when the ratio of the height H of the axial flow blades 151 to the diameter D of the axial flow impeller 15 is in the range of 0.3 to 0.6, both the problem of gas binding of the centrifugal pump can be effectively solved and no negative impact on the liquid delivery pump can be ensured.

[0047] Figure 7 Fig. 6 shows an exploded view of the liquid delivery pump according to an embodiment of the present application. For reference, Figure 7The pump shaft 17, which can be made of ceramic material or other materials with good corrosion resistance, wear resistance and high hardness, is first inserted into the top end recess 1261 of the cylinder 126 at the top of the outward protrusion 124 of the second housing 12. Then, the pump shaft 17 is passed through the hollow body 131 of the impeller assembly 13 to make the impeller assembly 13 sleeved on the pump shaft 17 and insert the cylinder 126 into the hollow body 131. Since the rotor 162 is integrated with the impeller assembly 13, the pump shaft 17 is also passed through the hollow portion 1621 of the rotor 162 to make the rotor 162 sleeved on the pump shaft 17. Finally, the first housing 11 containing the stator 161 (not shown) is sleeved on the outside of the integrated rotor 162 and impeller assembly 13 and fixedly installed on the second housing 12. The first housing 11 and the second housing 12 can be installed together in various suitable ways, such as screw connection, buckle connection or rigid connection. When the liquid delivery pump 10 is working, the rotor 162 and the impeller assembly 13 will rotate around the pump shaft 17.

[0048] Figure 8 A cross-sectional view of a liquid delivery pump according to another embodiment of the present application is shown; Figure 9 A bottom view of a liquid delivery pump according to another embodiment of the present application is shown. In combination with reference to Figure 8 and Figure 9 The exemplary liquid delivery pump 20 includes a first housing 21, a second housing 22, an impeller assembly 23 and a drive assembly 26. The second housing 22 includes a pump inlet 221, a pump outlet 222 and a pump cavity 223 fluidly connecting the pump inlet 221 and the pump outlet 222. The second housing 22 further includes a mouth portion 224 extending outwardly, and the pump inlet 221 is formed around the mouth portion 224.

[0049] The mouth portion 224 is further formed with a plurality of recesses 225 (e.g., four recesses) distributed in the circumferential direction of the shaft. It can be understood that the number of recesses 225 is not limited to four, and the number can be set according to actual needs. The recesses 225 can allow liquid to enter the pump cavity 223 from the pump inlet 221 in advance and contact the impeller assembly 23 when the liquid delivery pump 20 is not working, so that part of the air in the pump cavity 223 can be discharged from the recesses 225.

[0050] The impeller assembly 23 is at least partially disposed in the pump cavity 223 of the second housing 22. The impeller assembly 23 includes a centrifugal impeller 24 and an axial flow impeller 25 coaxially connected in series with the centrifugal impeller 24. The axial flow impeller 25 can be arranged adjacent to the mouth portion 224 of the second housing 22.

[0051] The axial impeller 25 can further include axial vanes 251 and an axial hub 252, the axial vanes 251 being arranged axially spaced on the axial hub 252. The number of the axial vanes 251 can be two or more, which can be set according to actual needs.

[0052] The drive assembly 26 is disposed at least partially within the receiving cavity 211 of the first housing 21 to drive the impeller assembly 23 to operate. In one embodiment, the drive assembly 26 can drive the axial impeller 25 to rotate to suck liquid from the pump inlet 221 into the pump cavity 223, and drive the centrifugal impeller 24 to rotate to deliver the liquid sucked by the axial impeller 25 to the pump outlet 222 via the pump cavity 223. When the drive assembly 26 drives the axial impeller 25 to rotate, the axial impeller 25 will suck liquid from outside the liquid delivery pump 20 into the pump inlet 221 through the axial force generated by the rotation of the axial impeller 25. Since the axial impeller 25 will generate self-suction force when rotating, a negative pressure can be formed at the pump inlet 221 to help the liquid quickly fill the pump cavity 223, so that the air originally existing in the pump cavity 223 is pushed by the liquid flow to the pump outlet 222 and discharged, ensuring that no air is retained in the pump cavity 223. At the same time, the liquid flows axially upward along the outside of the axial hub 252 of the axial impeller 25 and enters the centrifugal impeller 24 through the opening 241 at the bottom of the centrifugal impeller 24, and the drive assembly 26 drives the centrifugal impeller 24 to rotate. Under the rotation of the axial impeller 25, the pump cavity 223 is free of air and filled with liquid, and the centrifugal force generated by the rotation of the centrifugal impeller 24 further pressurizes the liquid in the pump cavity 223 and pushes the liquid to the pump outlet 222 for delivery, and finally the liquid is discharged from the pump outlet 222.

[0053] In one embodiment, the drive assembly 26 can be a brushless direct current motor. The brushless direct current motor generally has the advantages of reduced wear and tear due to the absence of carbon brushes, improved motor efficiency and reliability, and low noise. However, in other embodiments, the drive assembly 26 can also be other types of motors or structures with driving functions.

[0054] In one embodiment, the receiving cavity 211 defined by the first housing 21 can further include a first sub-cavity 211a and a second sub-cavity 211b. The stator 261 of the brushless direct current motor can be disposed in the first sub-cavity 211a. The rotor 262 of the brushless direct current motor can be disposed in the second sub-cavity 211b.

[0055] In one embodiment, the driving assembly 26 can further include a driving shaft 263 fixedly connected with the rotor 262 through the first bearing 27. The driving shaft 263 can be made of ceramic material or other material with good corrosion resistance, wear resistance and high hardness. The top of the driving shaft 263 is fixed in the second sub-cavity 211b through the second bearing 28. The first bearing 27 and the second bearing 28 can be made of graphite material or other material with good self-lubricating property, chemical stability and high temperature resistance. When the rotor 262 rotates continuously due to the electromagnetic torque, the driving shaft 263 is driven to rotate, and further drives the impeller assembly 23 coaxially connected on the driving shaft 263 to rotate.

[0056] Figure 10 An exploded schematic view of a liquid delivery pump according to another embodiment of the present application is shown. Referring to Figure 10 , the centrifugal impeller 24 is first sleeved on the lower end of the driving shaft 263 fixedly connected with the rotor 262 through the centrifugal hollow part 242 of the centrifugal impeller 24. Then, the axial flow impeller 25 is sleeved on the lower end of the aforementioned driving shaft 263 through the hollow part 253 of the axial flow hub 252. The centrifugal impeller 24 and the axial flow impeller 25 can be installed on the driving shaft 263 by clamping or other suitable fixed connection mode. Finally, the first casing 21 containing the stator 261 (not shown) is sleeved outside the aforementioned liquid delivery pump 20 and fixedly installed on the second casing 22. The first casing 21 and the second casing 22 can be installed together by various suitable modes, such as screw connection, buckle connection or rigid connection, etc. When the liquid delivery pump 20 works, the rotor 262 drives the centrifugal impeller 24 and the axial flow impeller 25 connected on the same driving shaft 263 to work, so that the centrifugal impeller 24 and the axial flow impeller 25 maintain the same rotational speed.

[0057] The present application can solve the gas binding problem without increasing additional water pipes or nozzles, and also improves the practicability and economy of the liquid delivery pump. By additionally arranging an axial flow pump at the front end of the centrifugal pump, the air inside the pump cavity and the impeller is forced to be discharged before the liquid delivery pump starts, which not only improves the reliability and stability of the liquid delivery pump, but also prolongs the service life of the liquid delivery pump and reduces the maintenance cost. Secondly, the same rotational speed is used to drive the centrifugal pump and the axial flow pump in the present technical solution, which simplifies the design of the equipment and reduces the complexity and cost of the equipment.

[0058] The above description is only an optional embodiment of the present application, and is not used to limit the embodiments of the present application. For those skilled in the art, the embodiments of the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present application shall be included in the protection of the embodiments of the present application.

[0059] While embodiments of the application have been described with reference to several particular embodiments, it will be understood that the embodiments of the application are not limited to the particular embodiments disclosed. Embodiments of the application are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the appended claims encompasses all such modifications and arrangements.

Claims

1. A liquid delivery pump characterized by, Comprising: a first housing defining a receiving cavity; a second housing comprising a pump inlet, a pump outlet, and a pump cavity fluidly connecting the pump inlet and the pump outlet; an impeller assembly comprising a centrifugal impeller and an axial impeller, at least partially disposed within the pump cavity of the second housing; the impeller assembly comprising a hollow body portion comprising a first end adjacent to the pump inlet and a second end opposite to the first end and distal to the pump inlet, the axial impeller formed at the first end of the hollow body portion, and the centrifugal impeller formed at the second end of the hollow body portion; a drive assembly at least partially disposed within the receiving cavity of the first housing, the drive assembly configured to drive the impeller assembly to operate.

2. The liquid delivery pump of claim 1, wherein, the drive assembly configured to drive the axial impeller to rotate to draw liquid from the pump inlet into the pump cavity, and to drive the centrifugal impeller to rotate to deliver the liquid drawn by the axial impeller to the pump outlet via the pump cavity.

3. The liquid delivery pump of claim 2, wherein, the impeller assembly integrally formed, the axial impeller and the centrifugal impeller coaxially rotating.

4. The liquid delivery pump of claim 1, wherein, the second end of the hollow body portion comprising a disc portion extending radially outward, the centrifugal impeller comprising a plurality of centrifugal blades circumferentially spaced apart on the disc portion, and the axial impeller comprising a plurality of axial blades circumferentially spaced apart on an inner wall of the first end.

5. The liquid delivery pump of claim 1, wherein, the drive assembly comprising a direct current brushless motor.

6. The liquid delivery pump of claim 5, wherein, the receiving cavity of the first housing comprising a first sub-cavity and a second sub-cavity, a stator of the direct current brushless motor disposed within the first sub-cavity, and a rotor of the direct current brushless motor disposed within the second sub-cavity and coupled with the impeller assembly.

7. The liquid delivery pump of claim 1, wherein, the second housing comprising an outward protrusion adjacent to the axial impeller, the outward protrusion laterally formed with a through hole to define the pump inlet.

8. The liquid delivery pump of claim 7, wherein, a top portion of the outward protrusion formed with a cylinder body inserted into the hollow body portion from the first end.

9. A liquid delivery pump characterized by, Comprising: a first housing defining a receiving cavity; a second housing comprising a pump inlet, a pump outlet, and a pump cavity fluidly connecting the pump inlet and the pump outlet, wherein the pump inlet is formed by a mouth portion extending outward from the second housing, and the mouth portion is formed with circumferentially distributed grooves; an impeller assembly at least partially disposed within the pump cavity of the second housing, the impeller assembly comprising a centrifugal impeller and an axial impeller coaxially connected in series with the centrifugal impeller, the axial impeller arranged adjacent to the mouth portion of the second housing; a drive assembly at least partially disposed within the receiving cavity of the first housing, the drive assembly configured to drive the impeller assembly to operate.

10. The liquid delivery pump of claim 9, wherein, the drive assembly configured to drive the axial impeller to rotate to draw liquid from the pump inlet into the pump cavity, and to drive the centrifugal impeller to rotate to deliver the liquid drawn by the axial impeller to the pump outlet via the pump cavity.

11. The liquid delivery pump of claim 9, wherein, the drive assembly comprising a drive shaft, the centrifugal impeller and the axial impeller sleeved on the drive shaft.

12. The liquid delivery pump of any one of claims 9 to 11, wherein, the drive assembly comprising a direct current brushless motor. the receiving cavity of the first housing comprising a first sub-cavity and a second sub-cavity, a stator of the direct current brushless motor disposed within the first sub-cavity, and a rotor of the direct current brushless motor disposed within the second sub-cavity and coupled with the impeller assembly. the second housing comprising an outward protrusion adjacent to the axial impeller, the outward protrusion laterally formed with a through hole to define the pump inlet. a top portion of the outward protrusion formed with a cylinder body inserted into the hollow body portion from the first end.

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