HIGH TORQUE DENSITY ELECTRIC MOTOR
Patent Information
- Application Number
- ES2024090013U
- Authority / Receiving Office
- ES · ES
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2023-07-12
- Publication Date
- 2026-09-11
- Estimated Expiration
- 2033-07-12
AI Technical Summary
Existing electric motors for aircraft and drones suffer from low specific torque per unit volume and unit mass, making them inefficient for use as aircraft engines.
A high torque density electric motor design featuring an annular stator with radially arranged teeth, a tangentially polarized rotor, and coil wire with a rectangular section made of grain-oriented steel, along with an open stator structure and high thermal conductivity insulating paper impregnated with varnish, enhancing magnetic field concentration and heat dissipation.
The design achieves a significant increase in specific torque per unit volume and mass, improving energy efficiency and reducing motor size and weight, while maintaining efficient heat management and cost-effectiveness.
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Abstract
Description
[0001] HIGH TORQUE DENSITY ELECTRIC MOTOR
[0002] Technical Field
[0003] The utility model relates to electrical engineering and can be used in electric motors for aircraft, drones and vertical take-off and landing aircraft.
[0004] Background Art
[0005] An analogue of the utility model is known - electric motor - US7679256, 06 / 10 / 2005, having the first section of the magnetic pole of the rotor, magnetized in the radial direction, and the second section of the magnetic pole of the rotor, magnetized in the direction of the axis of rotation; and a stator having a first stator magnetic pole section for generating magnetic flux in the radial direction and a second stator magnetic pole section for generating magnetic flux along the rotation axis direction.
[0006] The disadvantage of analogue is the low specific torque per unit volume and unit mass of the electric motor, which makes its use as an aircraft engine inefficient.
[0007] A close analogue of the device is known - flux concentrated-type motor - US20060061228A1, 09 / 16 / 2005, adopted as a prototype of the device, containing an annular stator in which the coil is wound on a plurality of radially spaced teeth and a rotor located in the center of the stator, and the rotor contains an annular rotor core, a plurality of teeth protruding from the annular rotor core in the direction of the stator and a plurality of magnets located between the teeth, while in the connecting section between the annular rotor core and the tooth a hole of small diameter is made, designed to insert a guide pin into it, and in the bridge connecting adjacent teeth, or in the end section of the tooth, i adjacent to the annular rotor core, a barrier is formed for the magnetic flux of the magnets to prevent its dispersion.
[0008] The disadvantage of the prototype is the relatively low specific torque per unit volume and unit mass of the electric motor, which makes its use as an aircraft engine inefficient.
[0009] The technical result of the proposed utility model is to provide a high, compared with analogues, specific torque per unit volume and, consequently, per unit mass of the electric motor, that is, to provide a high torque density necessary for its effective use as an aircraft engine.
[0010] Disclosure of the Utility Model
[0011] The technical result is achieved in a high torque density electric motor, containing an annular stator, in which the coil is wound on a plurality of teeth radially arranged, and a rotor located at the center of the stator, the rotor contains an annular rotor core and a plurality of teeth protruding from the annular rotor core in the direction of the stator, a plurality of magnets located between the teeth, wherein the magnets are tangentially polarized, the teeth of the stator and the annular rotor core with the teeth of the rotor are made of grain-oriented steel, the coil wire has a rectangular section, the stator has an open structure, and the stator coil is wrapped with insulating paper having a high thermal conductivity, which is impregnated with varnish.
[0012] Brief Description of Drawings
[0013] FIG. 1 is a cross section of the high torque density electric motor.
[0014] FIG. 2 is a cross-section of the high torque density electric motor without sidewalls. FIG. 3 is an enlarged fragment of a section of the high torque density electric motor, showing the lines of magnetic induction.
[0015] FIG. 4 is an enlarged view of the high torque density electric motor showing the arrangement of the coil.
[0016] FIG. 5 is a section of the optional assembly of the coaxial arrangement of two high torque density electric motors with propellers attached to them.
[0017] FIG. 6 is the assembly of stator.
[0018] FIG. 7 is the optional assembly of the coaxial arrangement of two high torque density electric motors with propellers attached to them.
[0019] The high torque density electric motor comprises an annular stator 1, as shown on Fig.l, in which the coil 2 is wound on a plurality of radially arranged teeth 3 of the stator 1 and a rotor 4 located in the center of the stator 1 , the rotor 4 contains an annular rotor core 5, as shown on FIG. 2, a plurality of teeth 6 protruding from the annular rotor core 5 in the direction of the stator 1 and a plurality of magnets 7 located between the teeth 6, the magnets 7 having a tangential polarization, as shown in figure 3, the teeth 2 of the stator 1 and the annular rotor core 5 with teeth 6 the rotor 4 is made of grain-oriented steel, the coil wire 2 has a rectangular section as shown on FIG. 4, the stator 1 has an open structure, and the coil 2 of the stator 1 is wrapped with high thermal conductivity insulating paper impregnated with varnish.
[0020] Best Mode for Carrying Out the Utility Model
[0021] Consider an example of the implementation of the high torque density electric motor. The annular stator 1 is made in the form of a ring, made up of steel sectors 8, connected by a dovetail lock 9, as shown on FIG.4. The copper coil 2 is wound on a plurality of radially placed teeth 3. The steel teeth 3 are fixed to the sectors 8 of the stator shell 1 by a dovetail lock 10. Coil 2 is made of copper wire, which has a rectangular section, as shown in FIG 2 and FIG 3. Such a wire increases the filling factor of the coil space by 70%, this increases the current density in the coil and increases the specific torque. Ohmic losses in the coil are calculated by the formula L = R * I2, where R is the coil resistance, I is the current strength. Due to the rectangular section of the coil in the implementation example, the resistance R is less than that of the existing analogues of the motor with a circular section of the coil by 2-2.5 times. Also, rectangular wire is much better at dissipating heat from itself than standard round or litz wire.
[0022] Sidewalls 11, 12 are fixed by screw on the sides of the ring of the stator 1, as shown on FIG3. Bearings 13, 14 are installed in the sidewalls 11, 12, as shown on FIG.l, 2. A rotor 4 is disposed on said bearings 11, 12. A plurality of teeth 6 protruding towards the stator 1 are fixed to the annular rotor core 5 of the rotor 4 by a dovetail connection 15, as shown on FIG.3. These parts are made of steel. The magnets 7 are fixed between the teeth 6 due to their wedge shape. The magnets 7 are tangentially polarized as shown in FIG.3. Due to this, the lines of magnetic induction 16 in them are directed tangentially to the direction of rotation of the rotor 4. The tangential polarization of the magnets concentrates the magnetic field more intensely than an array of Halbach magnets. Together with the location of the rotor 4 inside the stator 1, tangential polarization provides a higher specific torque per unit volume and mass than an engine with an external rotor of the same diameter and weight. Tangential polarization provides an increase in the magnetic field in the gap between the rotor and the stator by 1.2-1.3 times compared to motors that use surface mount magnets.
[0023] The teeth 2 of the stator 1 and the annular rotor core 5 with the teeth 6 of the rotor 4 are made of grain-oriented steel. Due to the higher magnetic conductivity of grain-oriented steel, as well as the ability to use a smaller tooth width to achieve the same effect and a large coil cross-sectional area, the use of grain-oriented steel increases the specific torque per unit volume and mass no of the electric motor by about 5% .
[0024] The stator 1 has an open design. This means that stator is not placed in the housing, but stator shell is the only housing motor has. It is implemented by that the steel teeth 3 are fixed to the sectors 8 of the stator shell 1 by a dovetail lock 10.
[0025] 115 The rotation of the rotor 4 ensures efficient convective heat transfer. In addition, the coil 2 of the stator 1 is wrapped with an insulating paper having high thermal conductivity, which is impregnated with varnish. Standard Nomex is used as insulating paper. High thermal conductivity paper ST6000 can also be used. The described means of cooling the engine are necessary for the
[0026] 120 efficient removal of heat from the considered high torque density electric motor with a specific per unit volume and mass, since it has a higher specific heat release per unit volume. The more heat can be removed from the motor, the more current can be used, the more torque the motor will have.
[0027] The open stator also makes it possible to significantly reduce the cost of
[0028] 125 the motor design, since the outer casing, which is the most expensive part of the motor, is no longer needed. Motor is sealed and complies with IP67.
[0029] Industrial Applicability
[0030] The above description proves the possibility of implementation of proposed utility model using known industrial technologies.
[0031] 130 The combination of the above features of a high torque density electric motor, namely, tangential polarization of magnets, stator teeth and annular rotor core with rotor teeth made of grain-oriented steel, rectangular elongated coil wire cross-section, open stator design with coil wrapped with insulating paper, which has a high thermal conductivity, impregnated with varnish, allows you to achieve a high value of specific torque and effectively use the engine as an aircraft engine.
[0032] Aviation and drones require engines with maximum torque per volume and per mass. The larger the diameter of the propeller and the slower it rotates, the more efficient the motor is in a given application. The proposed technical solution has these characteristics. In addition, due to its small volume, it creates less resistance to the oncoming air flow in flight, and the low mass of the engine provides greater energy efficiency.
[0033] FIG. 5 illustrates an example of such a motor application. It has two coaxially located electric motors 17, 18 with a high torque density with screws attached to them. Shaft 19 is a support for motor stators. Propellers are fixed to motor by folding propeller connections 20, 21 to create a traction force for the movement of the aircraft.
[0034] The features of the high torque density electric motor listed above have resulted in a range of motors with the following features:
[0035] 1) an engine with a mass of 1.2 kg, a diameter of 100 mm, with a specific torque per unit mass of 6 Nm / kg;
[0036] 2) an engine with a mass of 5 kg, a diameter of 150 mm, with a specific torque per unit mass of 12 Nm / kg;
[0037] 3) an engine with a mass of 15 kg, a diameter of 250 mm, with a specific torque per unit mass of 17 Nm / kg. The values of specific torque are given for the rated operation of the motor, peak values can be up to 2 times higher.
Claims
ClaimsHigh torque density electric motor, containing an annular stator, in which the coil is wound on a plurality of teeth radially arranged, and a rotor located at the center of the stator, the rotor contains an annular rotor core, a plurality of teeth protruding from the annular rotor core in the direction of the stator, and a plurality of magnets located between the teeth, characterized in that the magnets are tangentially polarized, the teeth of the stator and the annular rotor core with the teeth of the rotor are made of grain-oriented steel, the coil wire has a rectangular section, the stator has an open structure, and the stator coil is wrapped with insulating paper having a high thermal conductivity, which is impregnated with varnish.