Variable speed electric pump

Abstract

To provide a small, inexpensive variable speed pump capable of efficiently cooling power electronics and an outer rotor type permanent magnet electric machine. SOLUTION: A small, inexpensive variable speed pump (100) for improved cooling of an outer rotor motor having a wet end / fluid chamber (101), a power electronics variable speed drive (102), a liquid cooling plate (103), and an outer rotor permanent magnet (104). The drive (102) has a liquid cooling plate (103) with cooling tubes (5a, 5b) between the power electronics strategically located adjacent to the wet end / fluid chamber (101) and an outer rotor electric motor (104) having a rotor (9) located outside a stator (6) having concentrated windings (7). The cooling tubes (5a, 5b) allow liquid to flow through an inlet pipe (5a) and discharge through an outlet pipe (5b) to effectively cool both the power electronics on one side and the concentrated windings on the other side.

Description

[Technical field]

[0001] The present invention relates generally to electric motors, and in embodiments to cooling of electronics and outer rotor permanent magnet electric motors for pump applications. [Background technology]

[0002] Traditionally, induction motors are often used to drive pumps due to their high reliability, low cost, low maintenance, and high efficiency. These motors typically have an efficiency of 70%-85%.

[0003] In an induction motor, a voltage and current are passed through the stator, which creates a rotating magnetic field in the stator. Offset windings induce currents in the rotor cage bars, which create a magnetic field in the rotor. The motor rotates slower than the rotating magnetic field of the stator, causing slip, which increases with the motor's torque demands. Such motors, called asynchronous machines, are simple in construction but are not as efficient as permanent magnet motors. Also, variable speed drive induction motors are more complicated to control than permanent magnet motors.

[0004] On the other hand, in a permanent magnet motor, the rotor rotates due to the rotating magnetic field of the stator. This type of motor is called a synchronous machine. Since the magnets generate a magnetic field in the rotor, the permanent magnet motor is more efficient than an induction motor of the same size, which generates a magnetic field in the rotor due to induced current flowing through the cage bars. Variable speed drive of a permanent magnet motor is very simple compared to an induction motor.

[0005] In recent years, industries such as automotive, aerospace, marine, and rail are undergoing a rapid transformation, primarily aimed at reducing carbon emissions. This global drive towards electric propulsion systems is creating new business strategies in the pump industry as well, making them greener and more energy efficient. Apart from efficiency, designing small and energy-efficient pumps is the most important aspect.

[0006] Previously, pumps were cooled using air cooling methods, but this was inefficient compared to liquid cooling, as liquid absorbs heat approximately 24 times faster than air. Liquid's large specific heat capacity is more than four times that of air, making it an ideal coolant for pump applications where a cooling liquid is already present in the system.

[0007] China Patent Publication No. CN113482939A, a patent application entitled "High-efficiency water-cooled outer rotor type permanent magnet intelligent water pump with integrated controller", discloses a high-efficiency water-cooled outer rotor type permanent magnet intelligent water pump with integrated controller, in which a pump body is disposed in a shell, an impeller is disposed in the pump body at a water inlet and connected and fixed to the pump body via an impeller lock nut, a front-end cover is connected and fixed to the shell and connected and fixed to the pump body via a front bearing, a rear-end cover is connected and fixed to the shell and connected and fixed to the pump body via a rear bearing, a stator core is fixed to the front-end cover via a stator core fixing presser plate, a stator coil is disposed on the stator core, a heat conductive adhesive is provided at the end of the stator coil on the front-end cover side, and a heat conductive adhesive is disposed between the stator core and the front-end cover. The invention detects the water pressure at the water outlet through a pressure sensor, realizes energy saving and intelligent control, and uses the working medium water to directly cool the front cover connected to the stator core, thereby enhancing the heat dissipation effect."

[0008] The CN113482939A application relates to cooling of an outer rotor type permanent magnet water pump, and the arrangement of the impeller, motor, and pressure sensor improves heat dissipation. The application of the CN113482939A application focuses only on heat dissipation of the stator, and the working medium water is used to directly cool the front cover connected to the stator core. Also, a thermally conductive adhesive is arranged between the stator core and the front cover to improve cooling. The CN113482939A application does not disclose or teach that heat-generating power electronics are subjected to active cooling. By actively cooling the power electronics (variable speed drive), the power electronics can function in an enclosed space where the variable speed drive is prone to failure due to excessive heat generation inside the housing.

[0009] The embodiments disclosed herein provide pumps to improve heat dissipation for variable speed power electronics and outer rotor electric machines in applications such as pumping, heating, ventilation, and air conditioning (PHVAC), and industrial applications. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] China Patent Publication No. CN113482939A Summary of the Invention

[0011] To achieve the above objectives, embodiments of the present invention include a variable speed pump for PHVAC, industrial applications, and the like.

[0012] According to an embodiment of the present invention, the variable speed pump comprises a wet end / fluid chamber / fluid compartment, a variable speed drive including power electronics and a cover, a liquid cooled plate, and an outer rotor permanent magnet motor, all surrounded by a housing and the wet end / fluid chamber.

[0013] In the present invention, the wet end / fluid chamber may include a fluid inlet, an outlet, and a rotatably mounted impeller that draws in the fluid through the fluid inlet and expels the fluid through the outlet of the wet end / fluid chamber, the impeller being connected via a shaft to the outer rotor motor that rotates the impeller.

[0014] The variable speed drive may also include power electronics and a cover. The power electronics are screwed and molded into a thermally conductive (10-30 w / mk) wet end / fluid chamber rear section. In some embodiments, no thermal paste or pad is required as an interface between the power electronics and rear section (b) since they are in contact with each other. One way to make this contact is to mold the rear section (b) directly onto the power electronics to form a fused contact. The fused contact allows the parts to make contact.

[0015] The power electronics printed circuit board (PCB made of high temperature FR4 material or other substrate material with thermal conductivity of 200-400W / mK, etc.) is fused to section (b), which is also made of insulating material (dielectric strength of 2500V / mm or more). The high thermal conductivity extracts heat from the power electronics and transfers it to the flowing liquid in the flowing liquid chamber. This direct cooling method does not require thermal paste, thermal conductive adhesive, or thermal pads.

[0016] In the present invention, the liquid-cooled plate may be screwed to a cover of the transmission. Screws are used to fix the cover and the liquid-cooled plate. An outer rotor motor stator hub is attached to the opposite side of the liquid-cooled plate where the screws pass through the opening of the variable speed drive mechanism. The liquid-cooled plate further includes a cooling pipe that transports, circulates, and discharges the liquid-cooling fluid.

[0017] According to an embodiment of the present invention, the electric motor of the variable speed pump is an outer rotor type permanent magnet motor, and includes a stator with concentrated windings and a rotor arranged on the shaft outside the fixed stator. The rotor further includes a permanent magnet embedded in the inner diameter of the rotor and rotating together with the rotor. A vane is attached to the front surface of the rotor body to circulate air inside the pump.

[0018] The liquid-cooled plate is arranged to have a double cooling function from both sides. The power electronics cover is directly connected to the liquid-cooled plate on one side, and the stator hub is also connected to the liquid-cooled plate on the other side. For example, the power electronics cover may comprise a plate that abuts or is adjacent to the surface of the liquid-cooled plate. The heat from both sides is extracted by the liquid flowing inside the cooling plate. With this technique, the entire variable speed pump can be significantly miniaturized.

[0019] It will be understood by those skilled in the art that the power electronics arranged opposite the cover can also be contacted with the cover via thermal pads of different thicknesses, so that the power electronics on the opposite side of the PCB are cooled by the liquid cooling plate through the cover, allowing dual cooling of the power electronics, i.e., cooling the power electronics on both sides of the PCB directly with liquid cooling.

[0020] According to some embodiments, a variable speed pump comprises a fluid inlet for receiving fluid therein, a fluid outlet for receiving fluid therein, and an impeller disposed in a fluid chamber between the inlet and the outlet, the impeller being attached to the fluid inlet.

[0021] The fluid chamber includes a shaft connected to an electric motor and a transmission arranged adjacent to the fluid chamber, the transmission including power electronics and a cooling pipe interposed between the power electronics and the motor, the cooling pipe configured to receive liquid from an inlet pipe and discharge liquid from an outlet pipe.

[0022] The motor of the embodiment includes a rotor disposed outside a stator, the stator having concentrated windings. The liquid-cooled plate preferably provides cooling to the concentrated windings. In some embodiments, the power electronics includes a thermally conductive printed circuit board. Preferably, the thermally conductive printed circuit board is screwed and molded to the liquid-cooled plate. The thermally conductive printed circuit board preferably transfers heat from the power electronics to fluid in the wet end / fluid chamber and to the liquid-cooled plate.

[0023] In a preferred embodiment of the present invention, the rotor includes one or more permanent magnets and a rotor hub, the permanent magnets being attached to an inner diameter of the rotor hub and restricting displacement of the magnets during rotation. In some embodiments, the cover contains the power electronics and transfers heat from the power electronics to the liquid-cooled plate. In some embodiments, the housing encloses one or more of the variable speed drive, the electric motor, and the liquid-cooled plate and has an air inlet for passing air to cool the drive or the electric motor. In some embodiments, the motor includes a rotor, the rotor including one or more vanes for passing air as the rotor rotates.

[0024] In some embodiments, the housing may have an outlet for the air from the air inlet. In some embodiments, the power electronics are surface mounted, the surface being adjacent or proximate to the wet end / fluid chamber. In some embodiments, the power electronics includes one or more heat sink fins proximate to the wet end / fluid chamber or the liquid cooling plate. An input includes electrical communication with a variable speed drive to vary the speed of the motor.

[0025] The object of the present invention is to achieve efficient heat dissipation, energy efficiency, and reduced manufacturing costs in a variable speed pump equipped with small, high-power density liquid-cooled variable speed power electronics and an outer rotor permanent magnet electric machine with concentrated windings.

[0026] Another object of the present invention is to reduce active material usage in the motor which reduces the cost of the variable speed pump.

[0027] Therefore, according to the embodiment of the present invention, it is possible to provide a small-sized, inexpensive variable speed pump that can efficiently cool the power electronics and the outer rotor type permanent magnet electric machine. [Brief description of the drawings]

[0028] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to a specific embodiment, and is intended to facilitate explanation and understanding. [Figure 1] FIG. 2 is an exploded view of the variable speed pump according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of a variable speed pump. [Diagram 3] FIG. 2 is a cross-sectional view of a variable speed pump. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Embodiments of the present invention provide improved cooling of outer rotor motors in electronic devices and variable speed pumps in applications such as PHVAC and industrial applications with simpler and lighter construction.

[0030] The variable speed pump mainly comprises a wet end / fluid compartment (101), a variable speed drive (102), a liquid cooling plate (103), and an outer rotor electric motor (104), arranged as shown in FIG.

[0031] The wet end / fluid chamber (101) has a fluid inlet (1) and outlet (2) through which fluid is drawn between a rotating impeller (3) and the liquid is forced radially out through the outlet (2). The impeller (3) is attached directly to an elongated shaft (8) which is connected to the outer rotor electric motor (104) and passes between the variable speed drive (102) and the liquid cooling plate (103).

[0032] The variable speed drive (102) comprises power electronics (not shown), a PCB (4a) and a cover (4b), the PCB (4a) being strategically positioned adjacent to the wet end / fluid chamber (101) such that heat generated by the electronics (not shown) is transferred to the flowing liquid.

[0033] The power electronics printed circuit board (PCB) (4a) is screwed and secured to the rear section (3b) of a thermally conductive (10-30 w / mk) wet end / fluid chamber (101). Embodiments include thermal paste, thermally conductive adhesive, thermal pads, etc., but with this direct cooling method, thermal paste, thermally conductive adhesive, or thermal pads are not required.

[0034] The power electronics printed circuit board (4a) is in contact with section (3b) which is also made of insulating material (e.g., with a dielectric strength of 2500v / mm or greater) and the high thermal conductivity of the PCB (4a) allows it to extract heat from the power electronics and transfer it to the liquid flowing in the wet end / fluid chamber (101). The PCB may be made of high temperature FR4 material or substrate material (e.g., with a thermal conductivity of 200-400w / mk or the like, sufficient to transfer the heat of the power electronics).

[0035] As shown in the first embodiment, the liquid-cooled plate (103) has cooling pipes (5a, 5b) interposed between a cover (4b) made of power electronics (not shown) and an outer rotor type electric motor (104). The cooling pipes (5a, 5b) allow liquid to flow through the inlet pipe (5a) and discharge the liquid through the outlet pipe (5b). This makes it possible to effectively cool both the power electronics on one side and the concentrated windings (7) on the other side.

[0036] 1, the outer rotor type electric motor (104) includes a rotor (9) disposed outside a stator (6), the stator (6) including concentrated windings (7). A plurality of permanent magnets (10) are mounted on the inner diameter of the rotor hub to regulate the displacement of the magnets during high speed rotation due to centripetal force. Furthermore, stacking the magnets can reduce eddy current losses. The magnets and the outer rotor (9) are driven in a variable speed mode by the variable speed drive (102).

[0037] During operation, the electric motor (104) and variable speed drive (102) combined generate between 5%-20% of the power as heat, and dissipating this heat is important for the proper and efficient functioning of the pump without component failure. Heat generated by the power electronics (not shown) of the variable speed drive (102) is dissipated directly into the flowing liquid through the cover (4b) and thermal pads on the other side, in "fused contact" with the rear section (3b) of the wet end / fluid chamber (101) and the liquid cooled plate (103) on one side.

[0038] On the other hand, heat from the stator (6) and the concentrated windings (7) is mainly dissipated via the liquid cooling plate (103) that is in direct contact with the stator (6), as shown in FIG.

[0039] In addition, the electric motor (104) is not limited to a liquid-cooled type, and may be an air-cooled type in which air is circulated through the air intake (14) of the housing (12).

[0040] In this embodiment, the air inlet (14) directs air through the outer rotor electric motor (104), toward the concentrated windings (7), and out of the housing (12).

[0041] In the present embodiment, no air vent is provided, and air flows through the housing (12) only when the housing is closed, thereby preventing foreign matter from entering the pump.

[0042] In addition, by providing concentrated windings (7) to the stator (6), the amount of copper material used can be reduced by more than 40% compared to a distributed winding stator.

[0043] The pump (100) is powered by a utility power cable or a DC power source, and the voltage can vary from 12v to 1000v AC / DC. When the user turns on the variable speed drive (102), the user can input the pump speed request through the input unit (13) to operate the pump (100). A certain percentage of maximum power may be input to control the pump (100). The input unit (13) drives the pump (100) at a speed of the desired power level to circulate the liquid in the system. By varying the speed in this way, the cube law is satisfied and energy consumption can be saved. For example, a 20% reduction in speed reduces energy consumption by about 50%. A 50% reduction in speed reduces energy consumption by more than 88% of full power (e.g., 100%).

[0044] In one embodiment, the input 13 may be a keypad located on the pump housing 12 for inputting speed, diagnostics, operating mode selection, etc.

[0045] In other embodiments, the input 13 may be a wireless receiver and / or transmitter for communicating with a console, a smart phone, or a server or device associated with an application. The wireless receiver and / or transmitter may communicate via a short-range communication method such as Bluetooth or Wi-Fi, or via a long-range communication method such as SMS messages or radio waves.

[0046] The power electronics include a power factor correction circuit that improves the efficiency of the variable speed drive (102), whose efficiency remains high at 97%-99% for speeds above 50%. The efficiency of the electric motor (104) in that speed range is between 85%-98%.

[0047] In addition, the electric motor (104) can be manufactured by a slip-keying process, which involves less material waste than conventional methods, in order to reduce manufacturing costs and manufacturing times. The slip-keying process is characterized in that the stator winding is formed into a helical winding by one or more of compression, straightening, punching, and rolling, and cutting of the winding during formation is avoided or eliminated.

[0048] SUMMARY OF THE PRESENT DISCLOSURE The present invention provides a simple, compact, and inexpensive variable speed pump for efficiently cooling power electronics and outer rotor permanent magnet electric machines.

[0049] The above description shows the best mode for carrying out the present invention, and the technical scope of the present invention is not limited to the above-mentioned embodiment. Therefore, the present invention is not limited to the above-mentioned embodiment, method, and example, and is not limited to all the embodiments and methods within the scope of the invention described in the claims.

Claims

1. A variable speed pump, a. a fluid inlet (1) for allowing a fluid to flow in; b. A fluid outlet (2) for allowing the fluid to flow out; c. an impeller (3) mounted on a shaft (8) connected to an electric motor (104) and disposed in a fluid chamber between the inlet (1) and the outlet (2); d. a variable speed drive (102) disposed adjacent to the fluid chamber; e. A liquid-cooled plate (103) equipped with cooling pipes (5a, 5b); The variable speed drive (102) comprises power electronics; the cooling pipes (5a, 5b) are interposed between the power electronics and the electric motor (104) and are configured to receive liquid from an inlet pipe and to discharge liquid from an outlet pipe. A variable speed pump.

2. The electric motor (104) comprises a rotor (9) arranged outside a stator (6), the stator (6) comprising concentrated windings (7); 2. The variable speed pump according to claim 1.

3. The liquid cooling plate (103) cools the concentrated winding (7).

3. The variable speed pump according to claim 2.

4. The power electronics includes a thermally conductive printed circuit board (4a), 2. The variable speed pump according to claim 1.

5. The thermally conductive printed circuit board (4a) is screwed and molded to the liquid cooling plate (103).

5. The variable speed pump according to claim 4.

6. the thermally conductive printed circuit board (4a) is configured to transfer heat from the power electronics to the fluid in the wet end / fluid chamber (101) and to the liquid cooled plate; 5. The variable speed pump according to claim 4.

7. The rotor comprises one or more permanent magnets (10) and a rotor hub, the permanent magnets (10) being attached to the inner diameter of the rotor hub and restricting the displacement of the magnets during rotation.

2. The variable speed pump according to claim 1.

8. The cover (4b) encloses the power electronics and transfers heat from the power electronics to the liquid cooling plate (103).

2. The variable speed pump according to claim 1.

9. a housing (12) that houses at least one of the variable speed drive (102), the electric motor (104), and the liquid cooling plate (103); the housing (12) includes an air inlet (14) configured to allow the passage of air for cooling the variable speed drive (102) or the electric motor (104); 2. The variable speed pump according to claim 1.

10. The electric motor (104) has a rotor (9) having one or more vanes (11) for moving air through the rotor as it rotates.

10. The variable speed pump of claim 9.

11. The housing (12) has an outlet for air from the air inlet (14).

10. The variable speed pump of claim 9.

12. the power electronics are surface mounted, the surface being positioned adjacent to the wet end / fluid chamber (101); 2. The variable speed pump according to claim 1.

13. The power electronics includes one or more heat sink fins disposed proximate to the wet end / fluid chamber (101) or the liquid cooling plate (103).

2. The variable speed pump according to claim 1.

14. an input (13) in electrical communication with the variable speed drive (102) for varying the speed of the electric motor (104); 2. The variable speed pump according to claim 1.

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