A variable frequency motor for submersible electric pump and a sewage submersible electric pump

Abstract

The utility model discloses a kind of frequency conversion motor for submersible electric pump and sewage submersible electric pump. Frequency conversion motor for submersible electric pump includes motor cavity and wiring cavity, frequency conversion motor is permanent magnet frequency conversion motor, motor cavity is connected by upper end cover, stainless steel base and lower end cover, the side surface of stainless steel base is connected with terminal box, terminal box and frequency conversion control cover are connected to form wiring cavity;The inside of frequency conversion control cover is installed frequency conversion controller, and the connecting place of stainless steel base and terminal box is provided with outlet seat;Cable sealing device is provided on terminal box;Motor cavity bottom is provided with oil isolation chamber, and oil isolation chamber is connected by lower end cover and sealing cover. Permanent magnet frequency conversion motor of the application has the characteristics of high efficiency, high power factor, wide range high efficiency area, can realize soft start, wide voltage range operation. Frequency conversion controller is built-in, make overall structure compact, both convenient assembly and maintenance, can overcome the influence of long cable transmission to frequency conversion control, improve system control precision.

Description

Technical Field

[0001] This utility model relates to the field of submersible pump technology, specifically to a variable frequency motor for submersible pumps and a sewage submersible pump. Background Technology

[0002] Submersible electric pumps used for conveying sewage containing solid particles and fibers have been widely used in municipal sewage discharge, farmland irrigation and drainage, industrial and mining enterprises, and emergency rescue.

[0003] In existing technologies, submersible sewage pumps generally use ordinary asynchronous motors. These motors can only operate at a fixed speed and cannot adjust the flow rate according to the working conditions, resulting in energy waste due to reliance on valve throttling. They also have high starting current (5-7 times the rated current), which can impact the power grid and easily burn out the motor windings. Ordinary asynchronous motors have poor adaptability, operate at a fixed speed, and lack automatic protection functions such as overvoltage, overcurrent, overload, and overheating protection.

[0004] Furthermore, while some existing technologies utilize permanent magnet variable frequency motors in submersible sewage pumps, most employ an external variable frequency controller, separating it from the motor and connecting it via a cable. Under high-frequency modulation, the cable's distributed inductance and the motor's distributed capacitance can easily form a resonant circuit with the motor windings, leading to voltage overshoot and current distortion. This can result in the resonant voltage exceeding the motor's insulation withstand voltage, potentially causing winding breakdown. High-frequency radiated interference also affects surrounding equipment, and current distortion can cause inaccurate sampling feedback from the frequency converter. Utility Model Content

[0005] This invention provides a variable frequency motor for submersible pumps to overcome the aforementioned problems in the prior art. Simultaneously, this invention also provides a submersible sewage pump using the variable frequency motor of this invention.

[0006] For variable frequency motors, the technical solution of this application is as follows:

[0007] A variable frequency motor for a submersible pump is disclosed. The variable frequency motor is a permanent magnet variable frequency motor housed within a motor cavity. The motor cavity is composed of an upper end cover, a stainless steel base, and a lower end cover. A junction box is connected to the side of the stainless steel base, and the junction box is connected to a variable frequency control cover to form a wiring cavity. A variable frequency controller is installed inside the variable frequency control cover. A cable outlet is provided at the connection between the stainless steel base and the junction box. A cable sealing device is provided on the junction box. An oil isolation chamber is provided at the bottom of the motor cavity, and the oil isolation chamber is composed of a lower end cover and a sealing cover.

[0008] This invention employs a split-type dual-shell space design, utilizing a permanent magnet variable frequency motor. The main body of the permanent magnet variable frequency motor and the frequency converter are respectively housed in two independent, heat-dissipating, sealed motor cavities and wiring cavities. Firstly, the permanent magnet variable frequency motor, with its permanent magnet rotor, features high efficiency, high power factor, and a wide high-efficiency range, enabling soft starting of the water pump and operation within a wide voltage range. The motor windings are connected to the built-in frequency converter. When the frequency converter receives signals such as overvoltage, overcurrent, overload, or overheating, it automatically reduces the operating frequency and speed, keeping the operating current within allowable limits, thus protecting the motor. Secondly, the split-cavity design effectively solves the problem of heat accumulation between the motor body and the frequency converter. The heat generated by the motor is transferred to the stainless steel base via cooling oil. The outer perimeter of the stainless steel base is surrounded by water, which effectively carries away the heat generated by the motor. The frequency converter is mounted tightly on the frequency control cover, and the heat generated by the frequency converter is effectively carried away by the external water flow through the top and sides of the frequency control cover. Meanwhile, the built-in frequency converter allows for a compact combination of the motor and the frequency converter, facilitating assembly and maintenance, and adapting to the space and installation requirements of submersible pumps. The built-in frequency converter also overcomes the impact of long cable transmission on frequency conversion control, improving system electromagnetic compatibility and control accuracy. The cable sealing device and oil isolation chamber prevent water leakage into the motor housing and wiring housing.

[0009] Preferably, in the aforementioned variable frequency motor for submersible pumps, the variable frequency controller is filled with heat-dissipating potting compound. The variable frequency controller is mounted tightly on the variable frequency control cover and filled with heat-dissipating potting compound. The heat generated by the variable frequency controller is effectively carried away by external water flow through the top and sides of the variable frequency control cover.

[0010] Preferably, in the aforementioned variable frequency motor for submersible pumps, the outlet position of the terminal block is filled with epoxy resin. The epoxy resin prevents oil from entering the wiring cavity from the lead wire sheath and core after the motor cavity is filled with oil.

[0011] Preferably, in the aforementioned variable frequency motor for submersible pumps, a double-end mechanical seal is provided in the oil isolation chamber. One end face of the mechanical seal is connected to a sealing cover, and the other end face is connected to a lower end cover. The connection of one end face of the mechanical seal to the sealing cover prevents water from entering the oil isolation chamber; the connection of the other end face of the mechanical seal to the lower end cover prevents oil from entering the motor cavity.

[0012] Preferably, in the aforementioned variable frequency motor for submersible pumps, the permanent magnet variable frequency motor consists of a rotor and a stator. The rotor consists of a rotor core, embedded permanent magnets, and a motor shaft. The stator consists of a stainless steel frame and stator windings. The motor shaft is supported and fixed by a first support bearing and a second support bearing. An impeller is connected to the shaft extension end of the motor shaft. This structural design offers high reliability.

[0013] Preferably, in the aforementioned variable frequency motor for submersible pumps, the stainless steel base is provided with flanged flanges at both ends. The flanged flanges further secure the connection between the stainless steel base and the upper and lower end covers.

[0014] Preferably, in the aforementioned variable frequency motor for submersible pumps, a handle is provided on the top of the upper end cover. The handle facilitates the movement of the motor.

[0015] Preferably, in the aforementioned variable frequency motor for submersible pumps, the upper end cover is provided with a leak test hole. The leak test hole is used for checking the sealing performance of the motor cavity and for adding cooling oil.

[0016] Preferably, in the aforementioned variable frequency motor for submersible pumps, O-rings are provided on the upper end cover, lower end cover, sealing cover, and variable frequency control cover. The O-rings form a seal to prevent water from entering the motor cavity and wiring cavity.

[0017] The technical solution for this application regarding submersible sewage pumps is as follows:

[0018] A submersible sewage pump includes a drive motor; the drive motor is the aforementioned variable frequency motor for submersible pumps of this utility model. The submersible sewage pump can be used to transport sewage containing solid particles and fibers. The variable frequency motor employs a built-in controller design, which overcomes the influence of long cable transmission on frequency conversion control, improving system electromagnetic compatibility and control accuracy. The cable sealing device and oil isolation chamber prevent water leakage into the motor cavity and wiring cavity, and the specific structure features strong heat dissipation capacity and high reliability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the variable frequency motor for the submersible electric pump of this utility model.

[0020] Figure 2 This is a cross-sectional view of the variable frequency motor for the submersible electric pump of this utility model.

[0021] Figure 3 This is a cross-sectional view of the cable of the wiring cavity of the variable frequency motor for the submersible electric pump of this utility model.

[0022] The markings in the attached diagram are as follows: 1-Handle; 2-First support bearing; 3-Upper end cover; 4-Stainless steel base; 5-Rotor core; 6-Stator winding; 7-Embedded permanent magnet; 8-Motor shaft; 9-Second support bearing; 10-Cable outlet; 11-Variable frequency control cover; 12-Mechanical seal; 13-Sealing cover; 14-Junction box; 15-First screw; 16-Cable sealing device; 17-Second screw; 18-Leak test hole; 19-Lower end cover; 20-Mounting stop; 21-Shaft extension end; 22-Cable. Detailed Implementation

[0023] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings, but this should not be construed as limiting the present utility model. Contents not described in detail in the following embodiments are all common knowledge in the art or can be implemented using conventional technical means in the art.

[0024] Reference to embodiments of this utility model Figure 1-3 .

[0025] In this embodiment, the drive motor of the sewage submersible pump is a variable frequency motor, which includes two independently configured heat-dissipating motor chambers and a wiring chamber.

[0026] In this embodiment, the motor cavity is formed by bolting together an upper end cover 3, a stainless steel base 4, and a lower end cover 19. A permanent magnet variable frequency motor is installed inside the motor cavity, and the permanent magnet variable frequency motor mainly consists of a rotor, stator, and other major components.

[0027] In this embodiment, the rotor consists of a rotor core 5, embedded permanent magnets 7, and a motor shaft 8. The upper end cover 3 has bearing holes, within which a first support bearing 2 is installed. The lower end cover 19 has bearing holes, within which a second support bearing 9 is installed. The top and middle sections of the motor shaft 8 are supported and fixed by the first support bearing 2 and the second support bearing 9, respectively. The shaft extension end 21 of the motor shaft 8 is connected to an impeller.

[0028] In this embodiment, the stator is composed of a stainless steel base 4 and stator windings 6. At the connection points between the two ends of the stainless steel base 4 and the upper end cover 3 and the lower end cover 19, flanges are provided for further fixing.

[0029] In this embodiment, an oil isolation chamber is provided at the bottom of the motor cavity. The oil isolation chamber is composed of a lower end cover 19 and a sealing cover 13 bolted together. The oil isolation chamber is filled with oil to prevent water from entering the motor cavity. A double-end mechanical seal 12 is provided in the oil isolation chamber. One end face of the mechanical seal 12 is connected to the sealing cover 13 to prevent water from entering the oil isolation chamber; the other end face of the mechanical seal 12 is connected to the lower end cover 19 to prevent oil from entering the motor cavity. The sealing cover 13 is provided with an installation stop 20 for mounting the pump body.

[0030] In this embodiment, a junction box 14 is welded to the side of the stainless steel base 4. A cable outlet 10 is installed at the connection between the stainless steel base 4 and the junction box 14. The cable outlet position of the cable outlet 10 is filled with epoxy resin. The epoxy resin can prevent oil from entering the wiring cavity from the outer sheath and core of the lead wire after the motor cavity is filled with oil. The junction box 14 and the frequency converter control cover 11 are bolted together to form the wiring cavity. A frequency converter controller is installed on the inside of the frequency converter control cover 11 and is filled with heat dissipation potting compound. The junction box 14 is provided with a cable sealing device 16, which is used to seal the cable 22 to prevent water from entering the wiring cavity along the cable 22.

[0031] In this embodiment, grooves for installing O-ring seals are provided at the connection points of the upper end cover 3 and the stainless steel base 4, the lower end cover 19 and the stainless steel base 4, the lower end cover 19 and the sealing cover 13, and the frequency converter control cover 11 and the junction box 14. These grooves are used to install O-ring seals, forming a seal to prevent water from entering the motor cavity and the wiring cavity.

[0032] In this embodiment, a handle 1 is provided on the top of the upper cover 3 for carrying.

[0033] In this embodiment, the upper end cover 3 is provided with a leak test hole 18 for testing the sealing performance of the motor cavity and adding cooling oil.

[0034] In this embodiment, a first screw 15 is provided on the sealing cover 13. The first screw 15 is used to test the sealing of the oil isolation chamber and to act as an oil filling plug.

[0035] In this embodiment, a second screw 17 is provided on the junction box 14. The second screw 17 is used to test the sealing of the junction cavity and to act as an oil filler plug.

[0036] The working process of this utility model is as follows: When cable 22 is connected to a three-phase AC power supply, the current is first connected to the input terminal of the frequency converter. The frequency converter rectifies the power frequency AC power into DC power, and then inverts it into three-phase AC power with adjustable frequency and voltage through the IGBT inverter unit. The current is then output to the U, V, and W terminals of the stator through the three leads of the stator. The frequency converter output current is input to the stator winding 6, generating a rotating magnetic field. This magnetic field interacts with the embedded permanent magnet 7 on the rotor core 5, generating electromagnetic torque to drive the rotor to rotate synchronously. The rotor directly drives the impeller mounted on the shaft extension end 21 to rotate at high speed through the motor shaft 8.

[0037] The foregoing general description of the utility model and its specific embodiments should not be construed as limiting the technical solution of the utility model. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the utility model, to form other technical solutions within the protection scope of this utility model.

Claims

1. A variable frequency motor for a submersible electric pump, characterized in that: The variable frequency motor is a permanent magnet variable frequency motor, which is installed in the motor cavity. The motor cavity is composed of an upper end cover (3), a stainless steel base (4), and a lower end cover (19). A junction box (14) is connected to the side of the stainless steel base (4). The junction box (14) is connected to the variable frequency control cover (11) to form a wiring cavity. A variable frequency controller is installed on the inside of the variable frequency control cover (11). A cable outlet (10) is provided at the connection between the stainless steel base (4) and the junction box (14). A cable sealing device (16) is provided on the junction box (14). An oil isolation chamber is provided at the bottom of the motor cavity. The oil isolation chamber is composed of a lower end cover (19) and a sealing cover (13).

2. The variable frequency motor for a submersible pump according to claim 1, characterized in that: The frequency converter is filled with heat-dissipating potting compound.

3. The variable frequency motor for a submersible pump according to claim 1, characterized in that: The outlet position of the outlet socket (10) is filled with epoxy resin.

4. The variable frequency motor for a submersible pump according to claim 1, characterized in that: The oil isolation chamber is provided with a double-end mechanical seal (12), one end face of the mechanical seal (12) is connected to the sealing cover (13), and the other end face is connected to the lower end cover (19).

5. A variable frequency motor for a submersible pump according to claim 1, characterized in that: The permanent magnet variable frequency motor consists of a rotor and a stator. The rotor consists of a rotor core (5), embedded permanent magnets (7) and a motor shaft (8). The stator consists of a stainless steel frame (4) and stator windings (6). The motor shaft (8) is supported and fixed by a first support bearing (2) and a second support bearing (9). The shaft extension end (21) of the motor shaft (8) is connected to an impeller.

6. The variable frequency motor for a submersible pump according to claim 1, characterized in that: The stainless steel base (4) is provided with flanges at both ends.

7. A variable frequency motor for a submersible pump according to claim 1, characterized in that: The upper end cover (3) is provided with a handle (1) on top.

8. A variable frequency motor for a submersible pump according to claim 1, characterized in that: The upper end cap (3) is provided with a leak test hole (18).

9. A variable frequency motor for a submersible pump according to claim 1, characterized in that: O-rings are provided on the upper end cover (3), lower end cover (19), sealing cover (13) and frequency conversion control cover (11).

10. A submersible sewage pump, comprising a drive motor; characterized in that: The drive motor is a variable frequency motor for submersible pumps as described in any one of claims 1-9.

Images