RU2756842C1 - Air cooling device for electric motors - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, namely to air cooling devices for electric motors, and can be used as part of propeller-driven groups of vertical take-off and landing aircraft. The device includes a perforated housing with a lid to protect against ingress of solid particles and water droplets, fixed to the motor shaft, as well as an impeller for air intake and pumping through the motor windings, at least one cleaning disc installed in the housing and fixed to the motor shaft. The protective disk is made with slots forming channels for the passage of air to the cleaning disks. The output of mechanical impurities and liquid droplets occurs during the operation of the electric motor under the action of centrifugal forces by repelling them with rotating cleaning discs to the perforated walls of the housing, thereby the engine is cooled by an air stream cleaned of abrasive particles.

EFFECT: effective cooling of the electric motor with air purified from water droplets and abrasive particles with small dimensions of the device in the axial direction.

3 cl, 12 dwg

Description

Technology area

The invention relates to aeronautical engineering, specifically to multi-rotor rotary-wing aircraft with vertical take-off and landing, namely, to multicopters, in which the rotors are located in two parallel planes (tiers) located above and below the fuselage of the aircraft (LA).

The invention declares a new design of a multicopter, which provides an increase in reliability, stability and controllability of its flight as a result of achieving an optimal balance of stability and maneuverability of a multicopter due to a two-tiered arrangement of rotors in two parallel planes above and below the aircraft's center of gravity.

Prior art

For normal operation of electric motors, in particular electric motors driving the propellers of aircraft, it is necessary to ensure the greatest degree of their cooling and the ability to maintain the thermal state of the engine within the required limits under various operating modes and conditions. For powerful electric motors, cooling systems are used to circulate the air flow between their main structural elements. Thanks to this solution, thermal energy is taken directly from the heated windings and motor parts, which allows maintaining the required temperature even when operating at the maximum permissible power. For this, the motor cooling device must provide a sufficient cooling air flow. In this case, the air blowing over the parts of the electric motor should not contain moisture particles, as well as abrasive particles that can violate the integrity of the insulation of the electric motor windings.

In practice, different approaches are used to separate moisture particles and solid abrasive particles from the air stream. The first is based on the use of centrifugal forces, which remove solid particles. The principle of operation of such devices is as follows: the flow of dusty air is introduced into the apparatus through the inlet pipe tangentially. Under the action of centrifugal force, dust particles are carried out of the flow, settle on the walls of the apparatus and fall into the lower part of the device. The gas stream cleaned from dust is discharged through the outlet pipe. The disadvantage of this cleaning method is the large dimensions of the devices in the axial direction.

US Pat. No. 7,648,544 B2 (publ. 19.01.2010) presents a vortex tube separator for separating solid particles from a feed material containing gas and solid particles. The separation of dispersed particles from gases in this device occurs due to centrifugal forces created by the system of vortexing the gas flow. The solid particles are driven down by gravity. The disadvantage of such a device is the large dimensions in the axial direction.

In US patent 10233801 B2 (publ. 03/19/2019), a device for cleaning contaminated gas is presented, designed to separate small solid and / or liquid particles suspended in gas. The device is a vertical cylindrical body with fixed partitions with holes perpendicular to the body axis. Impellers, fixed on the rotating axis of the device, rotate between the partitions. The gas passes along the axis of the device through a plurality of holes in the fixed partitions, and the impurities contained in the gas accumulate on the rotating impellers and, under the action of centrifugal force, are thrown to the lateral surfaces of the cylindrical body. Due to the force of gravity, contaminants move to the bottom of the device and are removed from it. The disadvantage of the device is the need for a large number of baffle-impeller pairs to ensure effective separation of gaseous and solid and / or liquid fractions and, as a consequence, large overall dimensions in the axial direction. In addition, such a cooling system cannot create a high gas flow rate due to the high aerodynamic resistance.

Another approach to dusty air purification systems is to pass it through a filter system. However, with this method, it is impossible to create a sufficiently large air flow at the outlet of the device due to the high aerodynamic resistance.

In US patent 10,926,210 B2 (published 02/23/2021) an air purifier designed to remove solid particles and impurities is presented. The purifier has a cylindrical body with openings located at the bottom for intake of contaminated air. The air entering the purifier passes through a filter system, which may include one or more carbon pre-filters, a HEPA filter, a UV lamp, an electronic polarized air purifier, an ionized purifier, an ozone generator, or other filter / purification components. Suspended particles in the air are captured by the filter system. After the filters, the air is directed by a centrifugal fan to the outlets. The disadvantage of this air purifier is the inability to provide sufficient air flow to cool the external device.

In practice, cooling devices are also used that do not have cooling air purification systems. The disadvantages of such devices is the possibility of violating the integrity of the insulation of the motor windings due to the effect of abrasive substances present in the untreated air.

Patent RU 2570066 C2 (publ. 10.12.2015) presents an air cooling system for an electric motor, in which cooling occurs using a fan impeller mounted on the rotor shaft for rotation and with the ability to connect or disconnect from the rotor by means of an automatic coupling device. The disadvantage of such a device is the absence of a system for cleaning the air used to cool the electric motor from suspended particles and moisture particles.

In the patent US 10704561 B2 (published 07.07.2020), an air cooling system is presented, which is a multi-blade fan. The fan rotates in the plane of the hole in the casing, into which air is blown. On the outer edges of the fan blades, there are brushes made of polymeric or natural fibers. The brushes are located in such a way that they overlap the gap between the fan blade and the edge of the hole and can bend during the rotation of the fan blade when it hits the edge of the hole. The brushes provide a seal between the air blower and the edge of the housing opening. The system provides the required air flow rate, however, it does not provide cleaning of suspended solids in it.

The closest analogue of the claimed invention is the invention presented in patent RU 2713452 C1 (publ. 05.02.2020). The patent discloses an air-cooled closed electric machine. To ensure effective cooling, the device's housing is designed with a complex shape with external and internal annular fins to increase the effective cooling area. In addition, annular cooling fins are also made at the anchor of the electric machine. In this case, the ribs of one surface are located in the annular grooves between adjacent ribs of the other surface with the possibility of relative circumferential movement. The inner cavity of the electric motor armature is isolated from the external environment by means of stuffing box seals. The disadvantage of such a device is the complexity of manufacturing a structure with annular cooling fins, large dimensions of the device required to increase the effective cooling area, the impossibility of increasing heat removal from the electric motor with an increase in the released power, as well as the inevitability of penetration through the stuffing box seals of dirt and dust containing abrasive substances that do not removed from the closed internal space during the operation of the electric motor.

Brief Description of Drawings

FIG. 1. Diagram of the propeller group (hereinafter VMG) of aircraft with vertical take-off and landing.

FIG. 2a. Air cooling device for the upper electric motor of the VMG aircraft for vertical take-off and landing.

Phys. 2.b. Air cooling device for the upper electric motor VMG LA vertical take-off and landing assembly.

FIG. 2c. Diagram of air flow distribution in the air cooling device for the upper electric motor of the VMG aircraft for vertical take-off and landing.

FIG. H. Protective disk of the air cooling device for the upper electric motor of the VMG aircraft for vertical take-off and landing.

FIG. 4. The impeller of the air cooling device for the upper electric motor of the VMG aircraft for vertical take-off and landing: a - top view, b - side view.

FIG. 5. Disk for cleaning the air cooling device for the upper electric motor of the VMG aircraft for vertical take-off and landing.

FIG. 6. Air cooling device case for the upper electric motor of the VMG aircraft for vertical take-off and landing.

FIG. 7. Diagram of installation of disks for cleaning the air cooling device for the upper electric motor VMG LA vertical takeoff and landing.

FIG. 8a. Air cooling device for the lower electric motor of the VMG aircraft for vertical take-off and landing.

FIG. 8b. Diagram of the distribution of air flows in the air cooling device for the lower electric motor of the VMG aircraft for vertical take-off and landing.

FIG. 9. Protective disk of the air cooling device for the lower electric motor of the VMG aircraft for vertical take-off and landing.

Disclosure of the essence of the invention

The technical result, which the claimed invention is aimed at, is to ensure effective cooling of the electric motor due to the formation of an air flow sufficient for each operating mode of the electric motor, cleaned of moisture and abrasive particles, while maintaining the small dimensions of the device in the axial direction.

The specified technical result is achieved by the fact that the cooling air is cleaned due to centrifugal forces acting on solid particles arising from their interaction with rotating cleaning discs, and the engine is cooled by an air stream cleaned of abrasive particles.

The specified technical result is also achieved due to the fact that the elements of the cooling device are placed on the shaft of the cooled electric motor and rotate at the same frequency, and with an increase in the power consumed by the engine with an increase in the number of revolutions, the volume of cleaned air taken in and pumped through the filter and windings of the electric motor increases.

A significant difference between the proposed solution and the prototype is that the design of the device provides cooling of the electric motor with air purified from moisture and abrasive particles, and the flow of cooling air automatically increases with an increase in the power consumed by the engine.

Another significant difference between the proposed solution and the prototype is the simplicity of design and small dimensions of the device in the axial direction.

Embodiments of the invention

FIG. 1 shows a diagram of a propeller-driven group (VMP) of an aircraft with vertical take-off and landing. In the considered embodiment of the invention, the HVM includes the upper and lower screws of the aircraft (11), which are driven in rotation by electric motors (207) (Fig. 2a); bracket (12) for fastening the VMG to the aircraft rods (not shown in the diagram); upper (13) and lower (14) air cooling devices for electric motors.

1. Air cooling device for the upper electric motor of the propeller group of the vertical takeoff and landing aircraft.

FIG. 2a 2b shows an air cooling device for the upper electric motor VMG (13). The device includes a cover (201), which serves to prevent direct ingress of mechanical impurities and liquid droplets when the engine is not running, a protective disk (203), an impeller (204), which provides an intake of atmospheric air and its pumping through the windings of the electric motor, cleaning discs ( 205a, 205b, 205c). All elements of the device are sequentially assembled on the shaft (206) of the electric motor (207) and rotate at the speed of the electric motor. Adjusting washers (202, 202a, 202b, 202c, 202g) are installed between the individual elements of the device, providing the necessary clearance. The electric motor with the assembled elements of the device is placed in a perforated housing (208).

FIG. 2c shows a diagram of the distribution of air flows in the air cooling device for the upper electric motor of the VMG aircraft for vertical take-off and landing. Here (209) is the direction of the flow of the incoming atmospheric air, (210) is the direction of the mechanical impurities and liquid drops present in the atmospheric air emitted outside the cooling device, (211) is the outlet of purified air directed to cooling the motor windings.

FIG. 3 shows the protective disk of the air cooling device for the upper electric motor VMG LA (203), which prevents large mechanical particles from entering the cooling device. The incoming atmospheric air enters through the openings (31). Channels (32) serve for the passage of atmospheric air to the cleaning discs. (33) - mounting holes for assembling the elements of the cooling device. In another version of the air cooling device for the upper electric motor of the VMG aircraft of vertical take-off and landing, the protective disk can be made in the form of a ring, the slots of which are made in the form of a metal mesh.

FIG. 4 shows the impeller (204), which provides the intake of atmospheric air and its pumping through the motor cooling device. The impeller (204) has blades (41), which in the considered embodiment of the invention are made as a whole with the hub (42). The edges of each blade (41) are bent at some angle relative to the plane of the hub (42). Mounting holes (43) are made in the hub (42).

FIG. 5 shows a cleaning disk (205) of an air cooling device for the upper electric motor VMG LA. In the considered embodiment of the invention, the air cooling device for the upper electric motor VMG LA contains three cleaning discs (205). Channels (51) are made in the disk (205). Passing through the channels (51), the air is purified from small mechanical impurities and liquid drops. The channels (51) are oriented relative to the fastening holes (52) at a different angle α ° for each of the three discs (205).

FIG. 6 shows the case (208) of the air cooling device for the upper electric motor VMG LA. The housing (208) has holes (61) located between the cleaning discs (205). These holes are designed to remove mechanical impurities and liquid drops during the operation of the air cooling device for the upper electric motor VMG LA.

FIG. 7 shows a diagram of the installation of cleaning discs (205) of the air cooling device for the upper electric motor VMG LA. The discs (205) are installed in such a way that each subsequent disc partially overlaps the channels (51) of the previous disc. This is ensured by an appropriate angle α °.

The device works as follows. The air taken by the impeller (204) enters the device from the side through holes (31) in the protective disk (203) located on its periphery. The size and shape of these holes are selected based on the following considerations. First, the total area of the holes must provide a sufficient flow of inlet air necessary to cool the electric motor at maximum operating speed, and be no less than the cross-sectional area at the outlet of the electric motor. Secondly, it is necessary to exclude the penetration of large solid particles and liquid droplets into the device.

Further, passing through the channels (32) of the protective disc (203), the air passes through the channels (51) of the cleaning discs (205). In the considered embodiment of the invention, the air cooling device for the upper electric motor VMG LA contains three cleaning discs (205). The discs (205) are rotated relative to each other at an angle α °, which provides a partial overlap of the channels (51) in them. This, on the one hand, ensures a sufficient flow of air passing through the device, on the other hand, ensures the interaction of solid particles contained in the air with the system of disks, the particles receive a radial velocity component, are carried to the walls of the housing (208) and through the holes (61 ) fly out in it. The holes (61) are located between the cleaning discs (205). Their size and shape are chosen so as to ensure that mechanical impurities and liquid droplets escape through them during the operation of the device, but at the same time, do not reduce the air flow going to cool the electric motor. The total area of these holes must be at least 10 times less than the cross-sectional area at the outlet of the electric motor.

The dimensions and shape of the holes (31) in the protective disk (203), the holes (61) in the housing (208), the number of cleaning discs, the angles of mutual installation of the cleaning discs α ° are selected experimentally for a specific design of the electric motor.

2. Air cooling device for the lower electric motor of the propeller-driven group of vertical take-off and landing aircraft.

FIG. 8a shows an air cooling device for the lower electric motor of the VMG aircraft for vertical take-off and landing (14), and FIG. 8b is a diagram of the distribution of air flows in this device. The device (14) includes a protective disc (81), an impeller (204), cleaning discs (205a, 205b, 205c). All elements of the device are sequentially assembled on the shaft (206) of the electric motor (207). Adjusting washers (202, 202a, 202b, 202c, 202g, 202d) are installed between the individual elements of the device, providing the necessary clearance. The electric motor with the assembled elements of the device is placed in a housing (208). Atmospheric air enters the device (14) from below through the holes (91) of the protective disk (see Fig. 9). (210) - the direction of the mechanical impurities and liquid drops present in the atmospheric air emitted outside the cooling device, (211) - the outlet of the purified air directed to the cooling of the electric motor windings.

FIG. 9 shows the protective disk of the air cooling device for the lower electric motor VMG LA (207), which prevents large mechanical particles from entering the cooling device. Incoming atmospheric air enters through the openings (91). (92) - mounting holes for assembling the elements of the cooling device. In another version of the air cooling device for the lower electric motor of the VMG aircraft for vertical take-off and landing, the protective disk can be made of a metal mesh fixed to the lower part of the body (208).

The operation of the air cooling device for the lower electric motor of the VMG aircraft of vertical take-off and landing is similar to the operation of the above-considered air cooling device for the upper electric motor of the VMG aircraft of vertical take-off and landing.

Claims (3)

1. A device for air cooling of an electric motor, including a housing and an impeller fixed on the electric motor shaft, characterized in that it is equipped with a cover, a protective disk and at least one cleaning disk installed in the housing and fixed on the electric motor shaft, the protective disk is made with slots forming channels for the passage of air to the cleaning discs, made with slots forming channels for the passage of air, and the body is made with holes for the exit of mechanical impurities and liquid drops through them during the operation of the electric motor under the action of centrifugal forces by repulsion by rotating cleaning discs to the walls of the body, providing cooling of the electric motor with a cleaned air stream. 2. The device for air cooling of the electric motor according to claim 1, characterized in that when the number of cleaning discs is more than one, they are installed with partial overlap of the channels of each subsequent disc by the channels of the previous disc. 3. A device for air cooling of an electric motor according to claim 1 or 2, characterized in that the protective disk is made in the form of a ring, the slots of which are made in the form of a metal mesh.

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