Axial flow centrifugal hydraulic pump

Abstract

The present invention relates to an axial flow centrifugal hydraulic pump, in particular for the recirculation of water in swimming pools or hydrotherapy pools, comprising a direct current (DC) electric motor and the pumped water passing through the DC electric motor to cool and insulate the DC electric motor when in use.

Description

TECHNICAL FIELD

[0001] The present invention relates to an axial flow centrifugal hydraulic pump, particularly for recirculating water in a swimming pool or spa. Further, but not limited to this, the pump includes an extremely low voltage (ELV) direct current (DC) electric motor with inherent variable speed control, and the water being pumped passes through the DC electric motor to cool and soundproof the DC electric motor when in use. BACKGROUND

[0002] Centrifugal hydraulic pumps are a common type of pump used to recirculate fluids, such as water, in both residential and industrial applications, such as pumping water in a swimming pool or spa. A centrifugal pump generally consists of at least one rotating radial impeller that draws water in towards its center and expels the water from the pump by centrifugal force. Water enters the center or eye of the impeller from one direction and is flung out of the impeller by centrifugal force at a 90 degree angle to the direction of entry. This abrupt change in flow direction results in hydraulic energy loss.

[0003] In some cases, a stationary vane or volute is used to improve the hydraulic efficiency of a centrifugal pump. However, for many low cost small residential pumps, particularly pool pumps, the vane or volute adds additional manufacturing cost and therefore is not used. As a result, these low cost pool pumps without a volute or vane are less energy efficient and generally require more electrical energy to achieve the same hydraulic result.

[0004] If a radial vane is used, the radial vane generally has a number of evenly spaced vanes that are generally one less than the number of vanes of the matching rotating radial impeller and is positioned around the outer diameter of the rotating centrifugal impeller. A volute can have one or two vanes (if self-priming) or no vanes at all. Both the radial vane and the volute work by directing the water out of the impeller in a "spiral" manner and directing the water to the discharge outlet of the pump. The vane or volute converts a given flow rate and given static pressure of the fluid to a lower flow rate and higher static pressure of the fluid with little energy loss.

[0005] While radial flow centrifugal pumps are by far the most common in today's small residential water pumps, there is another type of centrifugal pump - the axial flow centrifugal hydraulic pump or straight centrifugal hydraulic pump. The axial flow centrifugal hydraulic pump contains a different type of impeller, such as a Francis type impeller or a turbine type impeller. Francis type impellers or turbine type impellers are more commonly used in larger industrial pumps, such as pumps used in sewage treatment. These pumps are generally designed to achieve a higher flow rate at a lower pressure than a radial flow pump, unless it is a multi-stage pump. Since higher flow rates and lower pressures are desired, these pumps generally do not employ a matching vane to minimize energy loss.

[0006] Therefore, with rising electricity costs and increased efforts to reduce carbon dioxide emissions, there is a need for more efficient centrifugal hydraulic pumps that minimize energy loss, especially for domestic applications such as pool pumps. Furthermore, there is a need for quieter centrifugal hydraulic pool pumps with the potential for off-grid operation.

[0007] The foregoing discussion of documents, laws, materials, equipment, articles, and the like is included in this specification for the purpose of providing background information for the present invention. This does not imply or represent that any or all of these contents constitute part of the prior art, or that they were common knowledge in the relevant field prior to the priority date of the claims of this application. Summary of the Invention

[0008] According to an aspect of the invention, an axial-flow centrifugal hydraulic pump is provided, comprising: an axially extending pump body having an inlet at one end of the pump body and an outlet at the opposite end of the pump body; a direct current (DC) electric motor centrally disposed within the pump body and between the inlet and the outlet, and the DC electric motor having a central rotating shaft; a turbine impeller coupled to the DC electric motor via a rotating shaft, adjacent to the inlet and configured to rotate about an axis to pump fluid from the inlet toward the outlet within the pump body, the turbine impeller having a plurality of impeller blades; and a guide vane adjacent to the outlet and mounted on the pump body, the guide vane having a plurality of guide vane blades that match the impeller blades to generate laminar flow at the outlet as the pumped fluid flows through the guide vane, wherein the guide vane blades extend at least partially axially to the DC electric motor, and the pumped fluid passes through the DC electric motor to cool and insulate the DC electric motor during use.

[0009] Preferably, the axial-flow centrifugal hydraulic pump is used for the recirculation (and filtration) of water in the pool. The inlet is designed to receive water from the skimmer tank of the pool, and the DC electric motor is an extra-low voltage DC electric motor. However, those skilled in the art will understand that the axial-flow centrifugal hydraulic pump can also pump other fluids.

[0010] Extra-low voltage is defined by relevant standards and is typically within the DC voltage range of 24-48V. Axial-flow centrifugal hydraulic pumps can have a corresponding power range of 100-800 watts.

[0011] Preferably, the extra-low voltage DC electric motor operates on ripple-free DC power below 30V and can be safely submerged in a swimming pool or spa. Accordingly, in pool applications, the pumped water passes through the DC electric motor to cool and insulate it during use. Furthermore, because the axial-flow centrifugal hydraulic pump occupies little space and has no external cooling fan, it can also be installed underground, for example, in a pit or sump adjacent to the pool.

[0012] However, it is understandable that axial-flow centrifugal hydraulic pumps can also be used in other applications, such as fountain pumps, spa pumps, sump pumps, irrigation pumps, and underwater propulsion devices or jetpacks.

[0013] In this implementation, the extra-low voltage DC electric motor of the axial-flow centrifugal hydraulic pump is powered by one or more photovoltaic panels and / or batteries. Compared to a corresponding radial-flow centrifugal hydraulic pump with a corresponding impeller diameter and input power, the axial-flow centrifugal hydraulic pump operates with a higher overall unit efficiency (e.g., up to 50% higher). Furthermore, compared to a corresponding radial impeller and matching radial guide vanes, the matched turbine impeller and guide vanes in this implementation can deliver significantly higher flow rates (e.g., up to 70% more water flow). Therefore, in some applications, the axial-flow centrifugal hydraulic pump can operate off-grid using photovoltaic solar panels (e.g., 390W PV solar panels) and batteries.

[0014] In this implementation, the battery serves as a backup power source for one or more PV solar panels. For example, the battery is a 50A / h lithium iron phosphate (LiFePO4) battery.

[0015] In this implementation, the guide vane blades and turbine impeller blades are evenly spaced around the guide vane and turbine impeller, respectively. The number of guide vane blades also differs from that of the turbine impeller blades. For example, the guide vane has seven evenly spaced guide vane blades, and the turbine has eight evenly spaced turbine impeller blades. This matching turbine impeller and guide vane minimizes energy losses associated with converting mechanical energy into hydraulic energy of the pumped fluid via a centrifugal impeller driven by an electric motor. Compared to radial flow pumps, the axial-aligned inline design of the axial-flow centrifugal hydraulic pump also reduces energy losses associated with changes in the directional flow of the pumped fluid and minimizes pressure drop.

[0016] In this implementation, each blade of the turbine impeller extends axially from the inlet and spirally from the impeller's wheel eye. Furthermore, each guide vane extends axially from the outlet and spirally as well. The shape of the guide vanes thus guides the fluid away from the impeller, achieving a gentle, gradual fluid deflection, thereby creating laminar flow. The reduced turbulence from laminar flow further reduces pump energy losses.

[0017] In this implementation, the guide vanes are adjacent to the pump body and extend radially toward the DC motor. As previously mentioned, the guide vanes extend at least partially to the DC motor, allowing the pumped fluid to pass through the DC motor in a laminar flow manner, thereby cooling and insulating the DC motor during operation. Typical centrifugal pumps, on the other hand, require an additional external air fan to cool the motor, which is noisy and requires additional power.

[0018] In this embodiment, the turbine impeller blades extend radially toward the pump body from the rotating shaft adjacent to the DC electric motor. Furthermore, in this embodiment, the diameter of the turbine impeller is within the width of the guide vanes. That is, the axial-flow centrifugal pump achieves a compact design with its in-line configuration, allowing the impeller diameter to be close to the pump body diameter, thereby increasing the water flow rate relative to the pump size.

[0019] In this embodiment, the rotating shaft has a conical cap adjacent to the inlet, which is configured to deliver fluid to the impeller eye at an angle to the axis. The conical cap, or cone, reduces turbulence in the fluid entering the impeller eye. In particular, the angle at which water enters the impeller eye is not 90 degrees to the impeller outlet as in a radial impeller. For example, the angle between the water entering the impeller eye and the axis is between 40 and 50 degrees (e.g., 40 degrees). This angle reduces the change in fluid direction within the impeller, thereby reducing energy loss. Additionally, the conical cap is made of metal and acts as a radiator to transfer heat from the rotating shaft to the fluid delivered to the impeller eye.

[0020] In one embodiment, the turbine impeller includes a back plate angled to its axis, and turbine impeller blades extend axially from the back plate. The angle of the back plate is between 1 and 89 degrees, and not 90 degrees for the reasons mentioned above. In another embodiment, the angle of the back plate is between 40 and 50 degrees (e.g., 45 degrees).

[0021] In one embodiment, the turbine impeller is coupled to the rotating shaft of a DC electric motor via a replaceable wear-resistant ring having a wear-resistant outer circumferential surface. The replaceable wear-resistant ring is located in front of the impeller but does not contact it.

[0022] In this implementation, the outer peripheral wear-resistant surface includes three stepped surfaces to create a tortuous path for fluid that does not flow through the impeller, reducing backflow towards the inlet. Backflow losses occur when fluid, under higher pressure, fails to enter the discharge side and instead forces its way back to the suction side. The stepped surfaces form five individual labyrinth-type seals to prevent backflow, thereby reducing energy loss. Furthermore, the backplate angle of the turbine impeller is between 40 and 50 degrees, which also provides additional backflow protection.

[0023] According to another aspect of the invention, an off-grid pumping system is provided, comprising: an axial-flow centrifugal hydraulic pump as described above, and one or more photovoltaic panels for photovoltaic power generation to supply power to an extra-low voltage DC electric motor.

[0024] In addition, the system may further include batteries for receiving power from one or more photovoltaic panels and for powering an extra-low voltage DC electric motor.

[0025] In implementation, the axial-flow centrifugal hydraulic pump can be used as a preferred control mechanism of the type described in the applicant's co-pending international patent application entitled "Controller for Controlling Movement in Water Applications." The pump can also be used in a pool skimming system of the type described in the applicant's co-pending international patent application entitled "Backwash Pool Skimming System," both of which were filed on the same date as this application. The contents of the two co-pending patent applications are incorporated herein by reference. Attached Figure Description

[0026] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein: Figure 1 This is a cross-sectional view of an axial-flow centrifugal hydraulic pump according to an embodiment of the present invention; Figure 2 This is a side view of an axial-flow centrifugal hydraulic pump according to an embodiment of the present invention; Figure 3 This is a perspective view of a turbine impeller according to an embodiment of the present invention; Figure 4 yes Figure 3 A cross-sectional view of a turbine impeller in a photograph; Figure 5 This is a cross-sectional view of a turbine impeller within the pump body according to an embodiment of the present invention; Figure 6 yes Figure 5 A further sectional view of the turbine impeller and the pump body in block E; Figure 7 This is a perspective view of a guide vane according to an embodiment of the present invention; Figure 8 This is a perspective view of a guide vane being mounted to the body of a DC electric motor according to an embodiment of the present invention. Figure 9 This is a cross-sectional view of an axial-flow centrifugal hydraulic pump according to an embodiment of the present invention; and Figure 10 yes Figure 9 A further cross-sectional view of the axial-flow centrifugal hydraulic pump. Detailed Implementation

[0027] Figure 1An embodiment of an inline axial-flow centrifugal hydraulic pump 10 is shown. The pump 10 includes an axially extending pump body 12 having an inlet 14 at one end and an outlet 16 at the opposite end. The pump body 12 is cylindrical, and a cylindrical DC electric motor 18 is centrally housed within the pump body 12 between the inlet 14 and the outlet 16 of the pump 10. The DC electric motor may be a brushless DC electric motor (BLDC).

[0028] In this embodiment, pump 10 is used for the recirculation and filtration of water in a swimming pool or spa. For example, inlet 14 is designed to allow water to pass through the area shown in the diagram. Figure 2 Pipe 15 receives water from the skimmer tank of the pool, and pipe 15 is connected to inlet 14 via a detachable threaded half union. Outlet 16 is designed to connect to the inlet 14, as also shown in the figure. Figure 2 Pipe 17 in the middle discharges water to the discharge port in the pool. Pipe 17 is connected to outlet 16 via a detachable threaded half-fitting. Figure 1 Arrow 20 in the diagram indicates the direction of water flow through pump 10.

[0029] As previously mentioned, the DC electric motor 18 is preferably an extra-low voltage (ELV) DC electric motor. Specifically, the ELV DC electric motor 18 operates at a ripple-free DC voltage typically below 30V, thereby enabling the motor 18 to be safely submerged in pool water and within the pump body 12 (classified as "O" zone in AS3000 wiring guidelines). The ELV motor 18 may have a power range of 100-800 watts and is used to rotate the central rotating shaft 21 housed within the waterproof motor body 19.

[0030] Typically, AC electric motors used in axial or radial centrifugal water tank pumps operate at 3000 rpm in countries using 240V / 50Hz and at 3600 rpm in countries using 110V / 60Hz. In this embodiment, the ELV DC motor 18 operates at a lower speed of approximately 2000-2400 rpm, with a design speed range between 1000 and 2800 rpm. This reduced pump speed offers several design advantages, including lower energy consumption and less noise.

[0031] Pump 10 further includes a turbine impeller 22 adjacent to inlet 14, coupled to a DC electric motor 18 via a rotating shaft 21. The turbine impeller 22 is configured to rotate about an axis to pump water axially from inlet 14 toward outlet 16 within pump body 12. Figure 3 As shown, the turbine impeller 22 has a plurality of impeller blades 24 evenly spaced around the turbine impeller 22 to pump water.

[0032] Figure 3It is also shown that each turbine impeller blade 24 extends axially from the inlet 14 and spirally from the wheel eye 23 of the impeller 22. The turbine impeller 22 also includes a back plate 25 angled to its axis, and the turbine impeller blades 24 extend axially from the back plate 25. Figure 4 In the most clearly shown embodiment, the back plate 25 is at an angle of 40 degrees. The turbine impeller blades 24 also originate from the rotating shaft 21 adjacent to the DC electric motor 18 (e.g., Figure 4 As shown, it extends radially toward the pump body 12.

[0033] Pump 10 further includes guide vanes 26 mounted to pump body 12 adjacent to outlet 16. A plurality of guide vane blades 28 of guide vane 26 match impeller blades 24 to create laminar flow of water at outlet 16 as the pumped fluid flows through guide vane 26. Guide vane blades 28 extend axially in part to DC motor 18, and the pumped water passes through DC motor 18 to cool and insulate DC motor 18 during operation.

[0034] As previously mentioned, the DC electric motor 18 is designed to operate at speeds between 1000 and 2800 rpm, which is optimal for achieving better flow characteristics in the turbine impeller 22. In this embodiment, the DC electric motor 18 is a high-efficiency permanent magnet DC electric motor, thus allowing for inherent DC-to-DC speed control via a motor controller (not shown). Additionally, the pump 10 includes a DC power supply (not shown) for the DC electric motor 18. As previously mentioned, the DC electric motor 18 may also be powered by one or more photovoltaic panels and / or by batteries (not shown). Because there is no need to convert electricity from AC to DC and then back to AC according to a "truncated" sine wave, the motor controller generates less heat and is therefore more efficient (e.g., in the 98%-99% range).

[0035] Figure 7 and Figure 8 The guide vane blades 28 are shown in more detail. The guide vane blades 28 are evenly spaced around the guide vane 26. The number of guide vane blades 28 differs from that of the turbine impeller blades 24, and in this embodiment, there are eight turbine impeller blades 24 and seven guide vane blades 28. This ensures that the impeller blades 24 never completely align with the guide vane blades 28 during rotation, thereby avoiding the possibility of pulsation during pump 10 operation and preventing unwanted vibrations in the pump 10.

[0036] The guide vane 26 may include a locking mechanism for assembling the pump 10. The locking mechanism is... Figure 9The locking cap 48 is shown in the diagram and operates on a torsion locking principle. For example, the locking mechanism could be a seven-latch locking mechanism that engages with corresponding grooves on the motor body 19, allowing the guide vane 26 to be locked onto the motor body 19 by twisting the locking mechanism approximately 19 degrees. Advantageously, the locking mechanism can quickly and reliably secure the guide vane 26 to the motor body 19 without the need for fasteners or tools.

[0037] The guide vane locking cap 48 can be made of ethylene propylene diene monomer (EDPM) rubber. Once the guide vane 26 is engaged with the motor end cap of the motor body 19, the press fit of the guide vane locking cap prevents the two parts from "loosening" after engagement. Thus, the guide vane locking cap strengthens the connection between the guide vane 26 and the motor body 19.

[0038] The locking cap 48 may also have an anti-airlock strip molded into the top of the molded part. When the pump 10 is installed vertically (i.e., suction end facing down), this effectively eliminates the possibility of "airlock" behind the turbine impeller 22.

[0039] The turbine impeller 22 is matched with the guide vanes 26 to generate laminar flow and reduce turbulent vortices, thereby reducing energy loss of the pump 10. In one embodiment, the angles of the eight turbine impeller blades 24 are matched with the angles of the seven guide vane blades 28 to generate laminar flow of water passing through the pump 10.

[0040] More specifically, each guide vane 28 extends axially and helically from the outlet 16 of the pump 10. Therefore, the guide vane 28 is preferably helical in shape, such that the extended guide vane 28 forms part of a helix, thereby achieving laminar flow of water at the outlet 16. The guide vane 28 also extends radially toward the pump body 12 via a lip or seal (not shown) toward the body 19 of the DC electric motor 18. The lip or seal helps reduce backflow of water within the pump. The diameter of the turbine impeller 22 is therefore within the width of the guide vane 28 to maximize the throughput of water through the pump 10. That is, a larger impeller diameter relative to the pump body diameter can be used in the pump 10 compared to a radial impeller that must be positioned outside the impeller diameter.

[0041] In addition, the rotating shaft 21 has a conical cap 30 (or cone) adjacent to the inlet 14, which is configured to deliver water at an angle to the axis to the wheel eye 23 of the impeller 22. Figure 5 The image most clearly shows that water enters through inlet 14 and passes through conical cap 30, thereby changing the angle at which the water is received by impeller 22. This angle is typically between 40 and 50 degrees to reduce the required directional change of the water in impeller 22, thus reducing energy loss.

[0042] The conical cap 30 or cone is made of metal (e.g., ZF Bronze) or stainless steel (e.g., 316 stainless steel) and also serves as a cooling device for the rotor of the DC electric motor 18. That is, the conical cap 30... Figure 9 The connector 46 shown transfers heat from the rotating shaft to the cooler water entering the pump. This improves the efficiency of the electric motor of pump 10. The connector 46 between the conical cap 30 and the rotating shaft can also be made of aluminum to improve heat transfer to the conical cap 30 and thus enhance its cooling effect. In this embodiment, the connector extends substantially into the conical cap 30 to ensure better heat transfer. Therefore, pump 10 has two motor cooling methods: 1) external – water passes through the outside of the DC motor, and 2) internal – through the conical cap 30.

[0043] For example, as indicated by arrow 20, water enters the impeller 22 at a 45-degree angle via the conical cap 30 from its source into the impeller eye 23. It can be seen that the diameters of the front and back plates of the impeller 22 are not equal, while all radial impellers are parallel and of equal diameter. The angled back plate 25 allows water to exit the impeller 22 in the same direction as it enters, thus achieving axial flow 20 of water in the pump 10.

[0044] The angle or spiral design of the guide vane blades 28 ensures that once the water leaves the impeller 22, the blades 28 gently guide the water to flow through the motor 18 and out of the pump 10 outlet 16 in a laminar flow manner, without significant turbulence.

[0045] Figure 1 , Figure 5 and Figure 6 The diagram shows a turbine impeller 22 coupled to the rotating shaft 21 of a DC electric motor 18 via a replaceable wear-resistant ring 32 with a wear-resistant outer circumferential surface. The wear ring 32 serves a dual purpose. First, it withstands any wear over time, such as wear caused by sand particles in water. The wear ring 32 is replaceable, so if the tolerance between the impeller 22 and the wear ring 32 is too large, causing a decrease in pump performance, the wear ring 32 can be easily replaced. Its second purpose is as an anti-backflow device.

[0046] The outer circumferential wear-resistant surface of the wear ring 32 includes three stepped surfaces to form a tortuous path for fluid outside the impeller within the pump body, reducing backflow towards the inlet. The first stepped surface forms a first labyrinth seal 34, the second stepped surface forms a second labyrinth seal 36 and a third labyrinth seal 38, and the third stepped surface forms a fourth labyrinth seal 40 and a fifth labyrinth seal 42. When water from the pressure side attempts to return to the low-pressure suction side, it circulates internally within the pump instead of being pumped out through a resistive conduit. The wear ring 32 provides a tortuous path for the water to reduce backflow and improve the efficiency of the pump 10.

[0047] Figure 9 and Figure 10 Another embodiment of pump 10 is shown, and in particular, additional components of pump 10 are shown. Figure 9 A removable wear ring 44, which can be made of EDPM rubber, is shown to self-lock within the suction housing. This allows for the formation of a waterproof seal without the need for additional O-rings or conventional threaded tape. The locking mechanism of the guide vane 26 can also include a wear ring to provide a waterproof seal without the need for additional O-rings.

[0048] Those skilled in the art will understand that the pump motor 18 is controlled by a controller. Figure 10 An embodiment of such a controller 58 adjacent to the motor 18 is shown. In this embodiment, the electronic components related to the control of the motor 18 are mounted inside the pump discharge port and on a PCB.

[0049] The PCB of the controller 58 is connected to the motor 18 via a three-prong connector 50 at the motor end and a short-wire or long-wire connector 52 at the controller end. The short-wire or long-wire connector 52 is matched according to the application. The short-wire or long-wire connector also includes a three-prong connector. Advantageously, the three-prong connector 50 and the wire connector 52 allow the electric motor 18 to be quickly assembled into the controller in the pump body 12. In embodiments where the controller is not adjacent to the motor 18, the long-wire version of the connector 52 is used. In embodiments where the controller PCB 58 is adjacent to the motor 18, the short-wire version of the connector 52 is used to provide space for the PCB 58.

[0050] The wiring connector has three pins, enabling quick and easy electrical connection of the three phases generated by the motor 18, and facilitating rapid, plug-and-play assembly of the motor 18 with the central discharge assembly of the pump 10. The short or long wiring connector 50 ensures consistency between the two main components, the central discharge section of the pump 10 and the electric motor 18, across all models of the pump 10, thus avoiding unnecessary duplication of high-cost components. In other words, through the quick and easy assembly of the connector 52, the short or long wiring connector 52 enables either internal control of the motor 18 via the controller 58PCB or external control of the motor 18.

[0051] Thermal pad 60 can be positioned near the PCB to transfer heat from the PCB to heat sink 66. The heat sink can be positioned near the PCBs of motor 18 and controller 58 to direct heat from motor 18 and the PCB to... Figure 9 The exhaust nose cone 62 shown is designed to enhance heat dissipation. The radiator can be made of aluminum.

[0052] The discharge nose cone 62 can be made of 316 stainless steel. The discharge nose cone 62 acts as a center locking mechanism to securely fasten the entire electric motor 18 to the discharge assembly of the pump 10. Thus, only one center nose cone and a 22mm socket wrench are required during assembly; no other tools or bolts are needed. As previously mentioned, the discharge nose cone 62 can also act as a heat dissipation device to transfer any heat generated by the non-drive end bearing of the electric motor 18, or, in embodiments with a PCB controller 58, any heat generated by the PCB.

[0053] In one embodiment, a two-piece exhaust bearing cooler 54 can be placed near the exhaust cone 62. This allows for quick and easy replacement of the motor bearings when needed. Another benefit is that the exhaust bearing cooler can act as a radiator to dissipate heat from the non-drive end bearings of the electric motor 18.

[0054] In this embodiment, a removable drive-end bearing 56 is positioned near the inlet. This component may be made of aluminum. This component dissipates any heat from the drive-end bearing. The removable drive-end bearing 56 transfers heat via a lateral airflow cooling path within the motor 18. A two-piece exhaust bearing cooler is also formed between the non-drive-end bearing and the drive-end bearing. Figure 10 The lateral airflow path 64 is shown. This achieves more uniform heat dissipation within the electric motor 18, thereby further improving the efficiency of the electric motor.

[0055] The pump may also include a flow guide component 68. The flow guide component may be positioned near the outlet 16. The flow guide component 68 may be made of EDPM rubber. The flow guide component 68 guides fluid through the central discharge section into the main discharge housing. The flow guide component may have design features substantially similar to a wear ring, as it is self-locking / secured into the discharge housing. This allows the flow guide component to form a waterproof seal without the use of additional O-rings or threaded tape. The flow guide component 68 has an internal lip seal, thus eliminating the need for an additional internal O-ring.

[0056] In this implementation, the guide vane 26 employs a 7-bladed "spiral" guide vane blade 28 to more efficiently strip water from the rotating 8-bladed impeller, thereby reducing turbulence. Less turbulence improves hydraulic efficiency. This produces more laminar flow rather than turbulent flow. As previously mentioned, the guide vane 26 is matched to the impeller blades 24, and the 7-bladed spiral guide vane 26 matches the 8-bladed impeller. This ensures that the vanes are never completely aligned with the impeller blades at any point during impeller rotation, thus preventing pulsation.

[0057] Figure 10 A brushless direct current (BLDC) electric motor 18 is shown centrally positioned within the pump body 12, thereby acting as a large and stable central "connecting bolt" 70. Typically, electric motors use at least four long internal connecting rods / bolts to lock / secure the two motor end caps to the stator. In this embodiment, four evenly spaced bolts on the outer periphery of the motor 18 lock each end of the motor 18 to the pump body 12; thus, the entire motor assembly doubles as a large central connecting rod, allowing the suction and discharge ends of the pump 10 to be secured between the outer tube / housing without additional internal or external connecting rods / bolts. The outer tube / housing may be transparent polycarbonate to allow observation of the pump 10.

[0058] The term “comprising” as used in this specification (including the claims) shall be interpreted as indicating the presence of a stated feature, complete object, step, or component, but does not exclude the presence of one or more other features, complete objects, steps, or components.

[0059] It should be understood that various changes, additions and / or modifications can be made to the parts described above without departing from the scope of the present invention.

Claims

1. An axial-flow centrifugal hydraulic pump, comprising: An axially extending pump body having an inlet at one end of the pump body and an outlet at the opposite end of the pump body; A DC electric motor is centrally located within the pump body, between the inlet and the outlet, and the DC electric motor has a central rotating shaft; A turbine impeller coupled to the DC electric motor via the rotating shaft, the turbine impeller being adjacent to the inlet and configured to rotate about an axis to pump fluid from the inlet toward the outlet within the pump body, the turbine impeller having a plurality of impeller blades; as well as A guide vane, mounted to the pump body adjacent to the outlet, has a plurality of vane blades that match the impeller blades to generate laminar flow of the pumped fluid at the outlet as the fluid flows through the guide vane. The guide vanes extend at least partially axially above the DC electric motor, and the pumped fluid passes through the DC electric motor to cool and insulate it during use.

2. The axial-flow centrifugal hydraulic pump as described in claim 1, characterized in that, The guide vane blades and the turbine impeller blades are evenly spaced around the guide vane and the turbine impeller, respectively.

3. The axial-flow centrifugal hydraulic pump as described in claim 2, characterized in that, The guide vanes differ in number from the turbine impeller blades.

4. The axial-flow centrifugal hydraulic pump as described in claim 3, characterized in that, The guide vane has 7 guide vane blades evenly spaced around the guide vane, and the turbine has 8 turbine impeller blades evenly spaced around the turbine impeller.

5. The axial-flow centrifugal hydraulic pump as described in any one of claims 2 to 4, characterized in that, Each of the turbine impeller blades extends axially from the inlet and spirally from the impeller's wheel eye.

6. The axial-flow centrifugal hydraulic pump as described in claim 5, characterized in that, Each of the guide vanes extends axially from the outlet and spirals outwards.

7. The axial-flow centrifugal hydraulic pump as described in claim 6, characterized in that, The guide vane blades are adjacent to the pump body and extend radially toward the DC electric motor.

8. The axial-flow centrifugal hydraulic pump as described in claim 7, characterized in that, The turbine impeller blades extend radially toward the pump body from the rotating shaft adjacent to the DC electric motor.

9. The axial-flow centrifugal hydraulic pump as described in claim 8, characterized in that, The diameter of the turbine impeller is within the width of the guide vane.

10. The axial-flow centrifugal hydraulic pump according to any one of claims 1 to 12, characterized in that, The rotating shaft has a conical cap adjacent to the inlet, the conical cap being configured at an angle to the axis to deliver fluid to the impeller's wheel eye.

11. The axial-flow centrifugal hydraulic pump as described in claim 10, characterized in that, The angle with respect to the axis is between 40 and 50 degrees.

12. The axial-flow centrifugal hydraulic pump as described in claim 10 or 11, characterized in that, The turbine impeller includes a back plate angled to the axis, and the turbine impeller blades extend axially from the back plate.

13. The axial-flow centrifugal hydraulic pump as described in claim 12, characterized in that, The angle of the back panel is between 1 and 89 degrees.

14. The axial-flow centrifugal hydraulic pump as described in claim 13, characterized in that, The angle of the back panel is between 40 and 50 degrees.

15. The axial-flow centrifugal hydraulic pump according to any one of claims 10 to 14, characterized in that, The conical cap is made of metal and acts as a radiator to transfer heat from the rotating shaft to the fluid being fed to the impeller's eye.

16. The axial-flow centrifugal hydraulic pump according to any one of claims 1 to 15, characterized in that, The turbine impeller is coupled to the rotating shaft of the DC electric motor via a replaceable wear-resistant ring having an outer wear-resistant surface.

17. The axial-flow centrifugal hydraulic pump as described in claim 16, characterized in that, The outer wear-resistant surface includes three stepped surfaces to form a tortuous path for fluid in the pump body that is not in the impeller, thereby reducing backflow of fluid toward the inlet.

18. The axial-flow centrifugal hydraulic pump as claimed in any one of claims 1 to 17, used for water recirculation in a swimming pool or spa, characterized in that, The inlet is designed to receive water from a skimmer tank in a pool or spa, and the DC electric motor is an extra-low voltage DC electric motor.

19. The axial-flow centrifugal hydraulic pump as described in claim 18, characterized in that, The ultra-low voltage DC electric motor is powered by one or more photovoltaic panels and / or by a battery.

20. An off-grid pumping system, comprising: The axial-flow centrifugal hydraulic pump as claimed in any one of claims 1 to 18, and one or more photovoltaic panels for photovoltaic power generation to power the extra-low voltage DC electric motor.

21. The off-grid pumping system as described in claim 20, characterized in that, It further includes batteries for receiving power from the one or more photovoltaic panels and for supplying power to the extra-low voltage DC electric motor.

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