A variable frequency induction motor for an aviation fuel pump

Abstract

The application provides a wide-frequency asynchronous motor for an aviation fuel pump, and belongs to the technical field of aviation electromechanical technology, which is composed of a shell assembly, a stator assembly, a rotor assembly, a capacitor assembly, an end cover assembly and an explosion-proof grille. The motor is adapted to 300-1000Hz wide-frequency operation, realizes 204 DEG C heat protection through a hot fuse connected in series with a stator winding, realizes explosion-proof through the explosion-proof grille, an inclined slot and an explosion-proof shell, improves the power factor through a capacitor assembly connected in parallel with a three-phase lead-out wire, and realizes more than 20% high slip through high-resistivity materials used for manufacturing rotor bars and end rings. The wide-frequency low-power-consumption operation of the motor is realized through the cooperation of various designs, the motor is adapted to the frequency of a power supply and the speed is adjusted according to a load, the safety and reliability of the aviation fuel pump motor are greatly improved, the power loss is reduced, and the structure is simple and suitable for aviation variable-frequency power supply working conditions.

Description

Technical Field

[0001] This invention belongs to the field of aviation electrical engineering, and specifically relates to a wide-frequency asynchronous motor for aviation fuel pumps. Background Technology

[0002] In aviation fuel pumps, commonly used drive motors include permanent magnet synchronous motors, fixed-frequency three-phase AC asynchronous motors, and variable-frequency three-phase AC asynchronous motors. Asynchronous motors have advantages such as simple structure, high reliability, good mechanical characteristics, low cost, and no need for control. Typical aircraft power supplies are variable-frequency power supplies with a frequency range of 360Hz to 800Hz and a supply voltage of 115V AC or 230V AC, making them wide-range power supplies. Aviation fuel pumps are centrifugal pumps, and the starting torque requirements of the motor are not high. The motor speed is approximately directly proportional to the frequency; therefore, the asynchronous motor speed at high frequencies is about 2.2 times that at low frequencies. However, the output power of a centrifugal load is approximately directly proportional to the cube of its speed. The pump's output power at high frequencies will be about 10.6 times that at low frequencies. In reality, the fuel delivery volume required at high engine speeds may be 3 to 5 times that at low speeds. Meeting the power requirements at low frequencies results in significant power waste at high frequencies, and the motor's output capacity decreases at high frequencies, placing higher demands on the motor's characteristics. Summary of the Invention

[0003] This invention provides an asynchronous electric mechanism for aviation fuel pumps, featuring thermal protection, explosion-proof function, adaptability to a wide frequency range, high power factor, and high slip.

[0004] This invention discloses a wide-frequency variable-frequency asynchronous motor for aviation fuel pumps, comprising a housing assembly, a stator assembly, a rotor assembly, a capacitor assembly, an end cover assembly, and an explosion-proof grille. A thermal fuse is connected in series on the stator assembly. The end cover assembly has a slanted slot. The explosion-proof grille is positioned at the motor output shaft end and engages with the slanted slot of the end cover assembly. The capacitor assembly is connected in parallel between the three-phase leads of the motor. The squirrel cage bars and end rings of the rotor assembly are made of high-resistivity material. All components are assembled to form an explosion-proof housing. The high-power-factor capacitor assembly and the high-slip rotor assembly work together to achieve wide-frequency, low-power operation of the motor.

[0005] Furthermore, the laminations of the stator assembly and rotor assembly are made of soft magnetic material with high saturation magnetic flux density, and the BH curve of the soft magnetic material is segmented and corrected in combination with the excitation characteristics of the asynchronous motor rotor.

[0006] Furthermore, the soft magnetic material is an iron-cobalt alloy magnetic steel material with a magnetic induction intensity of 2.4T.

[0007] Furthermore, the thermal fuse includes electrodes, sealing insulating adhesive, compression spring, moving piece, thermally sensitive material, fixed spring, and metal housing. Once the thermally sensitive material of the thermal fuse melts, it cannot be restored, and the circuit cannot be reconnected automatically after being broken.

[0008] Furthermore, the components constituting the explosion-proof housing are assembled through planar mating surfaces, saddle mating surfaces, or planar mating surfaces with saddles. The explosion-proof gap of the mating surfaces is designed with reference to industry standards, and the average roughness Ra of the mating surfaces does not exceed 6.3 μm. The explosion-proof housing is a cylindrical structure.

[0009] Furthermore, the capacitor assembly is a three-phase independent capacitor structure, with one capacitor connected in parallel to each phase lead of the motor. The capacitors are combined in series or in parallel according to the power factor requirements, and the capacitors are polypropylene capacitors.

[0010] Furthermore, the high resistivity metallic material is brass or tin bronze, with brass having a resistivity of 0.0307-0.064. Tin bronze has a resistivity of 0.087-0.176 at 20°C. .

[0011] Furthermore, the distribution, quantity, angle, and size of the inclined grooves are all designed to be adapted to the size of the motor housing and end cover, and the explosion-proof grille and the inclined grooves form an explosion energy attenuation channel.

[0012] Furthermore, the motor is a deep squirrel-cage asynchronous motor, which does not require a matching controller and can adaptively adjust its speed according to the frequency of the aviation variable frequency power supply and the fuel pump load.

[0013] Furthermore, the end cap assembly has at least three inclined slots, and the explosion-proof grille is a single-layer or double-layer metal grille structure.

[0014] This invention designs an aviation fuel pump motor with features such as thermal protection, explosion-proof, high power factor, high slip, and wide frequency conversion range, thereby improving the safety and reliability of the aviation fuel pump motor and saving power. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a cross-sectional view of the electric motor structure of the present invention; Figure 2This is an exploded view of the electric motor of the present invention; Figure 3 This is a diagram of the internal structure of the thermal fuse of the present invention; Figure 4 This is a schematic diagram of the oblique hole arrangement on the end cover surface of the motor end cover assembly of the present invention; Explanation of reference numerals in the attached drawings: 1. Housing assembly; 2. Stator assembly; 3. Rotor assembly; 4. Capacitor assembly; 5. End cover assembly; 6. Explosion-proof grille; 7. Thermal fuse; 1a. Electrode; 2a. Sealing and insulating adhesive; 3a. Compression spring; 4a. Moving plate; 5a. Positioning plate; 6a. Fixing spring; 7a. Housing; 8a. Thermal fusion material. Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0018] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0020] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0022] like Figures 1-3 As shown, this invention specifically designs a wide-frequency variable-rate asynchronous motor for aviation fuel pumps, comprising a housing assembly 1, a stator assembly 2, a rotor assembly 3, a capacitor assembly 4, an end cover assembly 5, an explosion-proof grille 6, and a thermal fuse 7. The thermal fuse 7 is connected in series on the stator assembly 2. The end cover assembly 5 has a slanted slot. The explosion-proof grille 6 is located at the motor output shaft end and cooperates with the slanted slot of the end cover assembly. The capacitor assembly 4 is connected in parallel between the three-phase leads of the motor. The squirrel cage bars and end rings of the rotor assembly 3 are made of high-resistivity material. All components are assembled to form an explosion-proof housing. The high-power-factor capacitor assembly and the high-slip rotor assembly work together to achieve wide-frequency, low-power operation of the motor. This invention provides a wide-frequency variable-rate, high-slip asynchronous motor for aviation fuel pumps, enabling safe operation of the motor within a wide frequency range and improving product safety and reliability.

[0023] The present invention mainly considers the following working characteristics in its design and has made corresponding matching designs, specifically reflected in: (1) Wide frequency range operation: The present invention provides a wide frequency asynchronous motor for aviation fuel pumps, which can operate in the frequency range of (300~1000) Hz and belongs to a deep squirrel cage asynchronous motor. In order to ensure that the motor can work normally in the range of (300~1000) Hz, especially the high output capability of the motor at high frequency, according to the formula E=4.44k*f*N*Φ, where E represents the back electromotive force of the motor, k represents the motor constant, f represents the operating frequency, N represents the total number of turns per phase, and Φ represents the magnetic flux per phase, when a motor is designed, the motor constant k and the total number of turns per phase N are constant values, then the magnetic flux per phase Φ is proportional to the voltage-frequency ratio E / f. For asynchronous electromotive force, the operating voltage U and the back electromotive force are almost equal, the motor operating voltage U is a constant value, then the magnetic flux per phase Φ is proportional to the voltage-frequency ratio U / f. As the frequency increases, the magnetic flux per phase decreases, and the output capability of the motor weakens. To ensure high-frequency output capability, the stator and rotor laminations of the motor are made of soft magnetic materials with high saturation magnetic flux density. Otherwise, to guarantee high-frequency output, low-frequency magnetic saturation will occur, leading to a decrease in the power factor and even burnout of the motor. This invention uses soft magnetic materials with high saturation magnetic flux density, such as 1J22 iron-cobalt alloy magnets, with a magnetic induction intensity as high as 2.4T. However, it is important to note that because asynchronous motors are electrically excited, the excitation current is small at low frequencies, and the magnetic field strength is insufficient, causing the lamination magnetic induction intensity to fall below 2.4T. When used in asynchronous motors, the BH curve needs to be corrected. During correction, the BH curve needs to be corrected segmentally, taking into account the rotor excitation characteristics of the asynchronous motor; otherwise, the motor will experience magnetic saturation at low frequencies, resulting in a large no-load excitation current and a low power factor.

[0024] (2) Thermal protection function Aviation fuel has high safety requirements. The temperature of aviation motors during operation cannot exceed a certain value of 204℃, otherwise the fuel vapor may ignite, endangering system safety. Simultaneously, the product itself must possess explosion-proof capabilities. Based on the required safety protection temperature and operating current, a certain number of thermal fuses are connected in series in the high-temperature areas of each phase winding of the stator assembly, primarily to provide overheat protection for temperature-sensitive components.

[0025] One type of thermal fuse used in the specific implementation of this invention is as follows: Figure 3 As shown, the thermal fuse 7 designed in this invention consists of an electrode 1a, a sealing insulating adhesive 2a, a compression spring 3a, a moving piece 4a, a positioning piece 5a, a fixing spring 6a, a housing 7a, and a thermal fusion material 8a. The electrode (left lead-out end), serving as the left external conductive lead-out end of the thermal fuse, extends through the center of the left end of the device; its inner end (internal end of the device) passes through the sealing insulating adhesive and serves as the left-side support and connecting base for the compression spring, providing a left-side current path and axial support for the compression spring. The sealing insulating adhesive fills the leftmost end of the device ( Figure 3The black area in the middle wraps around and secures the left end interface between the left electrode and the metal casing. This serves two purposes: firstly, it provides insulation between the electrode and the metal casing; secondly, it seals the left end of the device, preventing internal components from being affected by the environment, and simultaneously provides axial restraint for the compression spring on the left. The compression spring is fitted onto the inner section of the left electrode, with the left side supported by sealing insulation and the inner end restraint of the electrode, and the right side pressing against the left end face of the moving plate. Under normal conditions, it is in a compressed state, providing an axial thrust to the right for the moving plate, which is the power source for the fuse action. The moving plate is a conductive metal component. Its left end face abuts against the right end of the compression spring, and its right end face contacts the right-side positioning plate, enabling conduction between the left and right electrodes. The outer periphery of the moving plate has a non-contact or insulated fit with the inner wall of the metal casing, forming a conductive path only through the spring and the electrode. Under normal conditions, it maintains reliable contact with the positioning plate, keeping the circuit conductive. Two positioning plates, acting as insulating or conductive limiting components, are arranged in pairs between the moving plate and the fixed spring. On one hand, they guide and limit the axial position of the moving plate, ensuring its coaxial movement within the metal casing. On the other hand, they isolate the moving plate from direct contact with the right-side fixed spring and serve as an intermediate carrier for the moving plate's conduction, enabling current transfer from the left electrode and moving plate to the right-side path. The fixed spring is located between the positioning plates and the hot-melt material, fitted onto the conductive path (or central rod) at the center of the device. Its left side abuts against the positioning plates, while its right side is limited and supported by the hot-melt material. Normally compressed, it provides a leftward reaction force to the positioning and moving plates, balancing the thrust of the compression spring to keep the moving plate in the conductive position while maintaining the coaxiality and positional stability of the positioning plates. The hot-melt material is filled at the rightmost end of the device (…). Figure 3 The right-side area encloses and secures the inside of the metal casing on the right side, while also axially limiting the right end of the fixed spring. In its normal state, it is solid, fixing the right end of the fixed spring and maintaining force balance in the entire spring system. When the operating temperature is reached, the thermoplastic material melts, losing its limiting support for the fixed spring, and the balance is broken. The metal casing (electrode) serves as the outer shell of the device and also as the right-side conductive electrode; it encloses all internal components (compression spring, moving plate, positioning plate, fixed spring, thermoplastic material), with the left end sealed with insulating adhesive and the right end filled and sealed with thermoplastic material. Its inner wall provides coaxial mounting space for each component, and through connection with the right-side passage, it enables the right-side conductive function of the device. In its normal state, it forms a complete conductive circuit with the left-side electrode through the positioning plate, moving plate, and left-side electrode.

[0026] The operating temperature of the thermal fuse is the safety requirement temperature T. f ℃. When the temperature is below T f At ℃, the thermistor is in a solid state. Under the action of the release spring and the compression spring, the star-shaped contact contacts the electrode, and the circuit is in the connected state; when the temperature is higher than T... fAt a temperature of ℃, the thermistor melts, its volume decreases significantly, the compression spring loses its support, and under the action of the release spring, the star-shaped contact separates from the electrode, breaking the circuit. Once the thermistor melts, it will not return to its original state after the temperature drops, and the circuit will not be reconnected.

[0027] (3) Explosion-proof function When an explosion-proof motor operates in an explosive gas environment, flammable gas will inevitably enter the explosion-proof enclosure. When a spark "arc" or dangerous temperature is generated inside the enclosure, and its energy is sufficient to ignite the explosive gas mixture, the explosion flame will rush out of the enclosure from the explosion-proof gap. The flame energy will instantly decrease to the point where it cannot ignite the flammable gas outside the enclosure, thus preventing an explosion in the explosive gas environment.

[0028] When an explosion occurs inside the casing, it generates extremely high explosive pressure. Due to the relatively small explosion space, the blast wave propagation time is extremely short, and the distance between each stress point is very small relative to the blast wave range. Therefore, it can be considered that all parts are subjected to force simultaneously and equally. Thus, it can be simplified as a thin-walled casing subjected to uniformly distributed pressure, while the strength of components such as shafts is also considered. If the casing strength is insufficient, it will ignite the entire explosive gas atmosphere, causing significant loss of life and property. Therefore, the design of the explosion-proof casing is crucial for explosion-proof motors; it must be able to withstand the specified explosion pressure without damage or permanent deformation. Because damage or deformation will compromise the explosion-proof performance of the casing, the explosion-proof casing must have sufficient mechanical strength and rigidity.

[0029] In order to achieve the explosion-proof function, the present invention is designed with an explosion-proof grille arranged near the output shaft end, and an inclined slot opened at the oil inlet and outlet. The explosion-proof grille and the inclined slot are in a cooperative relationship.

[0030] The design of the inclined slots prevents flammable gases or liquids from directly escaping, further attenuating the explosion energy and improving / enhancing the explosion-proof performance. The distribution and angle of the inclined slots have a significant impact on explosion-proof performance and must be considered in the design based on the dimensions of the motor housing and end caps.

[0031] The components that make up the explosion-proof enclosure are assembled together by planar mating surfaces, non-planar mating surfaces, or a combination of planar and non-planar mating surfaces to form a complete explosion-proof enclosure. The safety gap between the mating surfaces is called the explosion-proof gap. Based on the gap extinguishing principle and referring to GB3836.2-2010, the gap and non-planar dimensions between different mating surfaces are designed, and the average roughness Ra of the mating surfaces must not exceed 6.3 μm.

[0032] According to the geometry of the explosion-proof motor housing, there are two types: one is a cylindrical structure; the other is a box-type structure. The motor assembly of this invention has a cylindrical structure, such as... Figure 2 As shown.

[0033] At the same time, the thermal protection function of the motor can also prevent the motor from overheating in the early stage, preventing the motor itself from becoming a source of explosion. Thermal protection is also one of the explosion-proof measures.

[0034] (4) High power factor To achieve a higher power factor for the motor at low frequencies, a capacitor assembly is connected in parallel between the three-phase leads of the motor. One capacitor is connected in parallel to each of the three phase leads of the motor. The power factor of the motor is adjusted by the capacitive load to achieve a higher power factor at low frequencies.

[0035] In the specific implementation process, according to the required power factor value, capacitors with appropriate capacitance values ​​are used in parallel or series to achieve a higher power factor at low frequencies.

[0036] (5) High slip ratio To achieve high slip, the rotor resistance is increased. Specifically, the squirrel cage bars and end rings of the squirrel cage rotor can be made of high resistivity materials. Depending on the slip range suitable for different power levels, brass or tin bronze can be selected. The resistivity of brass is in the range of 0.0307-0.064. Tin bronze has a resistivity as high as (0.087-0.176) at 20℃. It can achieve a high slip ratio of over 20%.

[0037] In this invention, if a high slip rate is not used, the motor speed at high frequency is about 3.3 times that at low frequency. The output power of the centrifugal load is approximately proportional to the cube of the speed. Therefore, the motor output capacity at high frequency is about 36 times that at low frequency, which places higher demands on motor design and results in power waste.

[0038] This invention improves the slip rate of the wide-frequency asynchronous motor at high frequencies, so that the motor speed at high frequencies is only about 2.1 times that at low frequencies. As a result, the output power of the pump at high frequencies is only about 9.2 times that at low frequencies, which can reduce power consumption at high frequencies and reduce the demand on the motor.

[0039] Wide frequency conversion asynchronous motors have strong output capacity at low frequencies, but also low speed. Aviation fuel pumps consume little power from the motor, resulting in a low power factor and wasted power.

[0040] High power factor and high slip linkage enable wide-frequency asynchronous motors to maintain low power consumption over a wide frequency range (300-1000) Hz.

[0041] For aircraft using variable frequency power supplies, compared to using permanent magnet synchronous motors, a controller is also required for driving, which increases product complexity and economic costs, and reduces reliability. Directly selecting a wide-frequency variable frequency asynchronous motor results in a more reliable structure and can automatically adjust the speed according to the power supply frequency, thus improving the safety and reliability of the product.

[0042] Example 1 This embodiment provides a low-power wide-range variable frequency asynchronous motor for aviation fuel pumps, suitable for low fuel delivery conditions. The specific structure and parameters are as follows: The overall assembly consists of a housing assembly, stator assembly, rotor assembly, capacitor assembly, end cover assembly, and explosion-proof grille. The explosion-proof housing is a cylindrical structure. The components are assembled using a planar and locating mating surface. The explosion-proof gap is designed according to GB3836.2-2010, and the average roughness Ra of the mating surface is 5.0μm. Stator and rotor laminations: 1J22 iron-cobalt alloy soft magnetic material is selected, with a magnetic induction intensity of 2.4T. The BH curve is modified in three segments according to the rotor excitation characteristics to adapt to the frequency ranges of 300~500Hz, 500~800Hz and 800~1000Hz respectively, so as to avoid low-frequency magnetic saturation. Thermal protection structure: One thermal fuse is connected in series in the high-temperature region of each phase winding of the stator assembly. The thermal fuse has an operating temperature of 204℃. The thermal sensitive material is a low melting point alloy. When the temperature exceeds 204℃, the thermal sensitive material melts, the circuit is automatically disconnected and cannot be restored. Explosion-proof structure: A metal explosion-proof grille is arranged at the motor output shaft end. The end cover assembly has 3 inclined slots with an angle of 45° between the inclined slots and the housing. The explosion-proof grille and the inclined slots form an energy attenuation channel. The size of the inclined slots is designed to be adapted to the diameter of the end cover. Power factor regulation: The capacitor assembly adopts a three-phase independent capacitor structure, with a 10μF polypropylene capacitor connected in parallel to each phase lead. The three-phase capacitors are not connected in series and are directly connected in parallel between the leads, which improves the power factor in the low-frequency range to above 0.9. High slip design: The squirrel cage bars and end caps of the rotor assembly are made of brass, which has a resistivity of 0.045 Ω·cm. It achieves a slip rate of 22%, and the motor speed at 1000Hz is 2.1 times that at 300Hz. The high-frequency output power of the fuel pump is 9.2 times that at low frequency, matching the power requirements of low fuel delivery conditions.

[0043] The motor in this embodiment operates stably in the frequency range of 300 to 1000 Hz, and its thermal protection and explosion-proof performance meet the safety requirements of aviation fuel pumps. Its power consumption in the wide frequency range is reduced by 30% compared to traditional motors. It has a simple structure, requires no additional controller, and is suitable for the application scenarios of low-power aviation fuel pumps.

[0044] Example 2 This embodiment provides a high-power wide-range variable frequency asynchronous motor for aviation fuel pumps, suitable for high fuel delivery conditions of aviation fuel pumps. The specific structure and parameters are as follows: The overall assembly consists of a housing assembly, stator assembly, rotor assembly, capacitor assembly, end cover assembly, and explosion-proof grille. The explosion-proof housing is a cylindrical structure, and the components are assembled using locating joint surfaces. The explosion-proof gap is designed according to GB3836.2-2010, and the average roughness Ra of the joint surface is 6.0μm. Stator and rotor laminations: 1J22 iron-cobalt alloy soft magnetic material is selected, and the BH curve is corrected in four segments to adapt to the frequency ranges of 300~400Hz, 400~600Hz, 600~800Hz, and 800~1000Hz respectively, to ensure the magnetic flux density is stable across the entire frequency range and avoid the decline in high-frequency output capability. Thermal protection structure: Two parallel thermal fuses are connected in series in the high-temperature region of each phase winding of the stator assembly, with an operating temperature of 204℃, which improves the redundancy of thermal protection and prevents the risk of overheating caused by the failure of a single thermal fuse. Explosion-proof structure: A double-layer metal explosion-proof grille is arranged at the motor output shaft end. The end cover assembly has 6 inclined slots with an angle of 60° between the slots and the shell. The depth and width of the inclined slots are designed to be adapted to the shell size. The double-layer explosion-proof grille and multiple inclined slots work together to achieve multi-stage attenuation of explosion energy and improve the explosion-proof level. Power factor regulation: The capacitor assembly adopts a three-phase capacitor series-parallel combination structure. Each phase lead is connected in parallel to two 20μF polypropylene capacitors connected in series, with a total capacitance of 10μF, which improves the accuracy of power factor regulation and raises the power factor in the low-frequency range to above 0.92. High slip design: The squirrel cage bars and end caps of the rotor assembly are made of tin bronze, with a resistivity of 0.12 at 20°C. It achieves a slip rate of 25%, and the motor speed at 1000Hz is 2.0 times that at 300Hz. The high-frequency output power of the fuel pump is 8.0 times that at low frequency, matching the power requirements of high fuel delivery conditions while avoiding high-frequency power waste.

[0045] The motor in this embodiment is adapted to a wide frequency conversion operating range of 300-1000Hz, has high thermal protection redundancy, stronger explosion-proof performance, and its power consumption in the wide frequency band is reduced by 35% compared with traditional high-power motors. It can stably drive high-capacity aviation fuel pumps and meet the high reliability and high safety requirements of the aviation field.

[0046] In both embodiments, the motor can adaptively adjust its speed according to the frequency of the aviation variable frequency power supply and the load of the fuel pump, without the need for an additional controller. The overall structure is simple, and installation and maintenance are convenient. The design features of thermal protection, explosion protection, high power factor and high slip work together to effectively solve the technical pain points of existing aviation fuel pump drive motors and adapt to the special working conditions of the aviation field.

[0047] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A wide-range variable frequency asynchronous motor for aviation fuel pumps, characterized in that, The device includes a housing assembly, a stator assembly, a rotor assembly, a capacitor assembly, an end cover assembly, and an explosion-proof grille. A thermal fuse is connected in series on the stator assembly. The end cover assembly has a slanted slot. The explosion-proof grille is positioned at the motor output shaft end and engages with the slanted slot of the end cover assembly. The capacitor assembly is connected in parallel between the three-phase leads of the motor. The squirrel cage bars and end rings of the rotor assembly are made of high resistivity material. All components are assembled to form an explosion-proof housing. The high power factor capacitor assembly and the high slip rotor assembly work together to achieve wide-frequency, low-power operation of the motor.

2. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The laminations of the stator and rotor assemblies are made of soft magnetic materials with high saturation magnetic density, and the BH curve of the soft magnetic materials is segmented and corrected in combination with the excitation characteristics of the asynchronous motor rotor.

3. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 2, characterized in that, The soft magnetic material is an iron-cobalt alloy magnetic steel material with a magnetic induction intensity of 2.4T.

4. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The thermal fuse includes electrodes, sealing insulating adhesive, compression spring, moving piece, thermally sensitive material, fixed spring, and metal housing. Once the thermally sensitive material of the thermal fuse melts, it cannot be restored, and the circuit cannot be reconnected automatically after being broken.

5. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The components constituting the explosion-proof housing are assembled through planar mating surfaces, saddle mating surfaces, or planar mating surfaces with saddles. The explosion-proof gaps of the mating surfaces are designed with reference to industry standards, and the average roughness Ra of the mating surfaces does not exceed 6.3 μm. The explosion-proof housing is a cylindrical structure.

6. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The capacitor assembly is a three-phase independent capacitor structure, with one capacitor connected in parallel to each phase lead of the motor. The capacitors are combined in series or in parallel according to the power factor requirements, and the capacitors are polypropylene capacitors.

7. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The high resistivity metallic material is brass or tin bronze, with brass having a resistivity of 0.0307-0.

064. Tin bronze has a resistivity of 0.087-0.176 at 20°C. .

8. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The distribution, quantity, angle, and size of the inclined slots are all designed to be adapted to the size of the motor housing and end cover. The explosion-proof grille and the inclined slots form an explosion energy attenuation channel.

9. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The motor is a deep squirrel cage asynchronous motor, which does not require a matching controller and can adaptively adjust its speed according to the frequency of the aviation variable frequency power supply and the fuel pump load.

10. The wide-range variable frequency asynchronous motor for aviation fuel pumps according to claim 1, characterized in that, The end cap assembly has at least three inclined slots, and the explosion-proof grille is a single-layer or double-layer metal grille structure.

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