AIR COOLING DEVICE FOR BRUSHLESS ELECTRIC MOTORS WITH AN EXTERNAL ROTOR

Abstract

This utility model relates to electrical engineering. The technical result consists in simplifying the design of an air cooling device for brushless electric motors with an external rotor, reducing the labor and material intensity of its manufacture, and reducing the weight of the motor in which said device is used. The air cooling device comprises an external rotor housing secured to the electric motor shaft together with an end cover made in the form of radial bridges. Said bridges are designed as blades with a front face that allows for the removal of external particles entering with the air flow when the blades rotate with said face in a direction perpendicular to the air flow. The blades are inclined relative to the transverse plane of the electric motor to direct the air flow onto the windings of the electric motor. 1 c.p. fils, 3 figs.

Description

[0001] FIELD OF TECHNOLOGY

[0002] The utility model relates to electrical engineering, namely to air cooling devices for electric motors, and can be used in power tools, such as lawn mowers, as well as in propeller-motor groups of aircraft with an oncoming air flow.

[0003] STATE OF THE ART

[0004] In numerous implementations of electric motors for powerful copters, brushless motors are mainly used, which prove to be more reliable, wear-resistant, durable and energy-efficient compared to brushed motors.

[0005] Therefore, let us consider well-known technical solutions based on brushless external rotor motors.

[0006] This engine is produced in numerous externally similar configurations and their modifications and consists of the following parts:

[0007] 1. internal stator of the motor with supply electric wires and windings on cores radially diverging relative to the axis of rotation of the shaft;

[0008] 2. The central cylindrical channel of the stator for the working shaft of the engine, with two parallel uniaxial bearings pressed into the walls of the channel;

[0009] 3. The working shaft of the engine, located in the central channel of the stator with the ability to rotate on two bearings fixed in the channel, spaced along the length of the channel;

[0010] 4. An end cap of the outer rotor pressed onto the end of the shaft extending outward relative to the stator and a device for attaching to it a propeller or other operating device for which this electric motor is used, for example, a line for a lawn mower or a propeller for a multicopter, etc.;

[0011] 5. The end cover of the outer rotor can be made solid, completely covering the outside of the stator winding, or made in the form of jumpers of various configurations, in particular radial ones, for fastening the cylindrical body of the outer rotor to the inner shaft of the motor;

[0012] 6. cylindrical outer rotor housing with magnets in the form of strips located inside the housing parallel to the ends of the stator cores with gaps between them.

[0013] When electric motors are operating without a large air flow, for example, when mowing the lawn or at low flight speeds of a multicopter, etc., cooling of the windings may be difficult and lead to overheating of the motor and a decrease in the service life of its windings.

[0014] In addition, operating the electric motor in rainy conditions or in the presence of suspended abrasive particles in the air blowing around the electric motor parts, such as sand dust, which can damage the integrity of the insulation of the electric motor windings, can also lead to its failure.

[0015] For the proper operation of electric motors, particularly those driving aircraft propellers, it is necessary to ensure maximum cooling and the ability to maintain the motor's thermal state within the required limits under various operating modes and conditions. High-power electric motors utilize cooling systems that circulate air between their main structural components. This solution extracts thermal energy directly from the hot windings and motor components, maintaining the required temperature even when operating at maximum power. To achieve this, the motor's cooling system must generate a sufficient flow of cooling air.

[0016] The closest device that offers a solution to this problem is the AIR COOLING DEVICE FOR ELECTRIC MOTORS, according to patent RU 2 756842 C1.

[0017] The device comprises a stator with windings on radial cores, a perforated rotor housing with a solid cover to protect against the ingress of solid particles and water droplets, all secured to the electric motor shaft, and an impeller for air intake and pumping through the electric motor windings. Cleaning disks are installed in the housing and secured to the electric motor shaft. The protective disk is slotted to form channels for air flow to the cleaning disks. Mechanical impurities and liquid droplets are released during electric motor operation under the influence of centrifugal force, repelled by rotating cleaning disks against the perforated walls of the housing. This cools the motor by an airflow free of abrasive particles.

[0018] DISADVANTAGES

[0019] The disadvantages of the prototype under consideration are the following design and functional solutions:

[0020] 1. The solid cover completely closes the engine airflow from the oncoming air flow;

[0021] 2. Air is sucked in from outside air at the side of the motor, with the flow drawn in in the opposite direction to the incoming air flow. Only then, under the cover, is the flow drawn in by a fan (impeller) into the stator in the same direction as the incoming air flow, creating a cooling effect that removes heat from the hot windings along the motor axis. Therefore, the dynamics of the incoming air flow are not utilized in its cooling;

[0022] 3. The air cooling and air purification device for removing water droplets and solid abrasive particles consists of a separate impeller, which functions as a fan and is mounted on the motor shaft under a solid cover. Slotted protective discs allow air to pass to the motor windings, and spacer adjusting washers between the cover, impeller, and protective discs provide a total of 12 separate additional motor components. This complicates the motor design, increases its material consumption, and increases labor costs during its manufacture.

[0023] It is proposed to eliminate the indicated disadvantages of the prior art by using an air cooling device for brushless electric motors with an external rotor, according to the proposed utility model.

[0024] DISCLOSURE OF THE ESSENCE OF THE UTILITY MODEL

[0025] The technical result of the proposed utility model of an air cooling device for brushless electric motors with an external rotor is a simplification of its design, a reduction in the labor intensity and material consumption during its manufacture, as well as a reduction in the weight of the engine, leading to an increase in the payload, in particular, for copters and multicopters.

[0026] The essence of the utility model is that instead of a solid protective end cover of the outer rotor, a separate impeller, protective discs with slots and spacers in the form of adjusting washers, the end cover of the engine is made in the form of radial bridges for fastening the cylindrical body of the outer rotor to the inner shaft of the engine in an amount of more than one with a configuration of baffles that provide the functions of throwing off drops of water and abrasive solid particles from the engine windings, thereby preventing them from getting inside the engine and blades that direct and enhance the oncoming air flow to the engine windings.

[0027] Thus, the entire set of additional 12 parts in the proposed utility model is missing, and instead of them, radial bridges are used for fastening the cylindrical housing of the outer rotor to the inner shaft of the engine, which are inherent in standard engines, but of a modified shape, providing the same functions as in the prototype: protecting the engine windings from the penetration of water droplets and abrasive solid particles into the engine to its windings and increasing the oncoming air flow for blowing the engine windings.

[0028] BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 shows the end cover of the outer rotor of a brushless electric motor.

[0030] Fig. 2 shows a top view of the end cover of the outer rotor of a brushless electric motor.

[0031] Fig. 3 shows a section of the outer rotor baffle blade of a brushless electric motor.

[0032] IMPLEMENTATION OF THE PROPOSED UTILITY MODEL

[0033] A device for air cooling of brushless electric motors with an external rotor, according to this utility model, can be used for efficient cooling of electric motors of this class.

[0034] The air cooling device for brushless electric motors with an external rotor (Fig. 1, 2, 3) is an end cover of the external rotor of a brushless electric motor, of a given configuration, consisting of n jumpers and combining the function of baffles and blades of a fan of an electric motor.

[0035] The function of the bump stop is performed by a vertical or close to vertical front in the direction of movement (rotation) flat cut of the end bridge of the engine cover, having the required thickness c = d / cos α, where d is the thickness of the blade, α is the angle of inclination of the blade to the transverse plane of the engine

[0036] The device operates as follows

[0037] When an external particle falls (moves) with a velocity v in the direction of the motor windings (inside the motor), a baffle of the required thickness from the front flat face of the jumper during its rotation as part of the external rotor with an angular velocity ω manages to completely cover the open sector of the motor end with a magnitude of φ=360° / n, which it protects, in order to guarantee the deflection of the falling particle during the time t of its fall to the depth of the thickness of the baffle c.

[0038] The inclination of the end bridge α to the end plane of the engine can range from 5° up to 45°, depending on the angular speed of the rotor rotation - the lower the rotation speed, the greater the angle - which allows, when rotating the rotor bridges in the form of inclined blades, to direct air or an incoming air flow inside the motor in the direction of its windings, which leads to their intensive blowing and heat removal.

[0039] Thus, the technical result achieved by the claimed utility model is achieved by blowing air onto the motor windings using an incoming air flow and intensifying it solely through the inclined rotating bridges of the end cap within the outer rotor. Moreover, intensifying the incoming air flow significantly increases the motor's service life due to its intensive cooling during operation.

[0040] The high rotation speed (around 15,000 rpm) of the end bridges in the outer rotor allows the flat ends of the bridges - the baffle blades - to throw away solid abrasive particles or liquid water droplets as they move across the air flow, away from the open end front part of the motor, preventing them from getting onto its windings.

[0041] The transformation of the outer rotor end bridges into inclined baffle blades made it possible to eliminate a large number of additional parts used in the prototype of the proposed utility model.

Claims

1. An air cooling device for electric motors with an external rotor, comprising an external rotor housing secured to the shaft of the electric motor together with an end cover made in the form of radial bridges, characterized in that the bridges of the end cover are made in the form of blades with a front edge made with the possibility of beating off external particles entering together with the air flow, when the blades rotate with said edge in a direction perpendicular to the air flow, wherein the blades have an inclination relative to the transverse plane of the electric motor to direct the air flow to the windings of the electric motor.

2. An air cooling device for an electric motor according to paragraph 1, characterized in that the angle of inclination of the blades relative to the transverse plane of the electric motor is in the range from 5° to 45°.

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