AXIAL FAN FOR AIR COOLED ELECTRICAL AIRCRAFT MOTOR

Described is a fan assembly for an electrical aircraft motor having an axial fan with an inner hub of a first diameter and an outer hub of a second diameter. The outer hub may be concentrically aligned with the inner hub. A plurality of blades may extend between the inner hub and the outer hub. The fan assembly may also have a mounting plate connected to the inner hub. The mounting plate may attach to a component of the electrical aircraft motor.

FIELD OF THE INVENTION

The field of the invention relates to cooling aircraft motors. In particular, cooling electrical aircraft motors.

BACKGROUND

Air cooled aircraft motors may rely on the circulation of air over cooling fins affixed to the motor or circulation of air directly over portions of the motor itself. The circulation of air may be satisfied by ram air from in-flight motion or by propeller wash.

SUMMARY

According to certain embodiments of the present disclosure, a fan assembly for an electrical aircraft motor is described. The fan assembly may include an axial fan. The axial fan may be defined by an inner hub having a first diameter and an outer hub having a second diameter. The outer hub may be concentrically aligned with the inner hub. A plurality of blades may extend between the inner hub and the outer hub. A mounting plate may be connected to the inner hub. The mounting plate may be connected to the inner hub and arranged for mounting the fan assembly to a component of the electrical aircraft motor. The first diameter may correspond to a third diameter of the electrical aircraft motor and the second diameter may correspond to a fourth diameter of the electrical aircraft motor.

According to certain embodiments of the present disclosure, a system including an electrical aircraft motor with an annular body and a set of cooling fins extending from the annular body is described. The system may also include an axial fan connected to the electrical aircraft motor. The axial fan may be defined by an inner hub having a first diameter that may correspond to the annular body. The axial fan may also be defined by an outer hub having a second diameter that may be concentrically aligned with the inner hub. The second diameter may correspond to the set of cooling fins. The axial fan may also include a plurality of blades extending between the inner hub and the outer hub.

According to certain embodiments of the present disclosure, a system including an electrical aircraft motor is described. The electrical aircraft motor may have a first annular housing that may include an electrical motor, a second housing that may include electronics, and a motor shaft that may be connected to the electrical motor. The system may also include an axial fan connected to the motor shaft. The axial fan may have an inner hub defined by a first diameter that may correspond to the first annular housing. The axial fan may also have an outer hub defined by a second diameter. The outer hub of the axial fan may be concentrically aligned with the inner hub, wherein the second diameter may be greater than the first diameter. The axial fan may have a plurality of blades extending between the inner hub and the outer hub.

DETAILED DESCRIPTION

The described embodiments of the disclosure provide an axial fan for an electrical aircraft motor. While the axial fan for the electrical aircraft motor is discussed for use with electrical aircraft motors, they are by no means so limited. Rather, embodiments of the axial fan may be used in any other suitable application for directing airflow, exhaust, and the like.

An electrical aircraft motor may be adequately cooled in certain scenarios but may require additional cooling in other scenarios. For example, an electrical aircraft motor may be adequately cooled by ram air when the aircraft is in flight or when propeller wash provides adequate airflow. Even so, the electrical aircraft motor may lack adequate cooling during ground operating condition such as taxiing. A lack of adequate cooling may be especially problematic when taxiing precedes takeoff, where the demands on the aircraft motor's power output may be the highest. A lack of adequate cooling of the power supply electronics may also negatively impact avionics equipment.

The lack of adequate cooling may be compounded by certain design decisions, such as housing power supply electronics close to the aircraft motor. Phase-change heat exchanges, such as water-cooling systems, may add undesirable weight, cost, or complexity to a design. An axial fan may compensate for the lack of airflow in some such scenarios.

In a particular example, the axial fan described herein may be driven by a motor shaft common to the propeller and aircraft motor. In an alternative example, a gearbox between the propeller and the motor shaft may drive the axial fan. In such an example, the gearbox may allow the propeller, motor shaft, or axial fan to operate at different rotational speeds. The axial fan may be directed at cooling fins that may be affixed to the aircraft motor and a housing including power supply electronics. The cooling fins may be positioned within an annulus flow region of an assembly containing the aircraft motor, the housing including the power supply electronics, and the motor shaft. The axial fan may be fashioned to increase weight minimally and may not draw consequential power from the motor shaft. The axial fan may be fashioned and positioned so that it does not negatively impact in-flight operating conditions like take-off, cruising, and landing. The axial fan may avoid such negative impacts by cooling fins on the housing of the aircraft motor rather than cooling the motor cavity of the aircraft motor directly.

Turning now to the figures,FIG.1is an isometric view of a fan-cooled motor system100for cooling an electrical aircraft motor103, according to at least one example. The fan-cooled motor system100includes a fan assembly101and the electrical aircraft motor103. The fan assembly101includes a spinner cone102and an axial fan104with blades106. An inner hub of the axial fan104may have a first diameter112and an outer hub of the axial fan104may have a second diameter114. In some examples, the axial fan104may have between seven and thirty blades106. In some examples, the axial fan104may have less than seven blades106or more than thirty blades106. As should be appreciated, the number of blades106may depend on certain design considerations such as flow required for cooling, fan weight, power required to spin the axial fan104, and other similar considerations. The axial fan104may be adapted to any suitable alternate geometry of the spinner cone102. In some examples, the axial fan104may be integral to the spinner cone102. The axial fan104may be formed of materials including but not limited to aluminum, stainless steel, fiberglass, graphite fiber, nickel-aluminum-bronze alloy, manganese bronze alloy, other metallic materials, composite materials, or other suitable similar materials.

The electrical aircraft motor103includes an aircraft motor108enclosed within a motor housing and power supply electronics110enclosed within an electronics housing. Airflow provided by the axial fan104may provide cooling via flow over the fins of the electrical aircraft motor103. In particular, electrical aircraft motor103may include cooling fins111, disposed radially about the housings of the aircraft motor108and the power supply electronics110.

FIG.2is a sectional view of the fan-cooled motor system100for cooling the electrical aircraft motor103, according to at least one example. As illustrated, the spinner cone102is aligned with a rotational axis202that extends through a center of the fan-cooled motor system100. The spinner cone102may be integrally formed with the axial fan104. The blades106of the axial fan104may direct airflow214through an annulus206of the spinner cone102. An inner hub226of the axial fan104may have a first diameter222and an outer hub228of the axial fan104may have a second diameter224. In some examples, the first diameter222may correspond to a smallest diameter of the inner hub226(e.g., a surface that faces towards the inner portion of the fan-cooled motor system100) or may correspond to a largest diameter of the inner hub226(e.g., a surface that faces away from the inner portion of the fan-cooled motor system100). In some examples, the second diameter224may correspond to a smallest diameter of the outer hub228(e.g., a surface that faces towards the inner portion of the fan-cooled motor system100) or may correspond to a largest diameter of the outer hub228). Thus, in some examples, the annulus206, which may be defined by the difference between the second diameter224as measured as the smallest diameter of the outer hub228and the first diameter222as measured as the largest diameter of the inner hub226, may be between 5 mm and 50 mm wide. The blades106can be axially or radially adjusted based on the width of the annulus206. The number of blades106may vary between seven and thirty, depending on the size of the annulus206.

The first diameter222may correspond to a third diameter223of the aircraft motor108and the second diameter224may correspond to a fourth diameter225of the aircraft motor108. The annulus206may also be defined by the difference between the fourth diameter225and the third diameter223of the aircraft motor108. The cooling fins111of the aircraft motor108may fit within the space between the fourth diameter225and the third diameter223. In some examples, the height of the cooling fins111.

The airflow214may fluidly communicate with cooling fins111of the aircraft motor108and power supply electronics110. The height of the cooling fins111may correspond to the size of the annulus206. Swirling airflow may be caused by the axial fan104. In some examples, the height of the cooling fins111may be about the same as the width of the annulus206. In some examples, the width of the annulus206may be greater than height of the cooling fins111or smaller than the height of the cooling fins111. In alternative examples, a flow-straightening component, such as an air straightener screen may be introduced between the axial fan104and the aircraft motor108to mitigate swirling airflow within the annulus206. The air straightener screen may include a pattern of hexagonal channels. In some examples, other form factors of flow-straightening components may be used.

The power supply electronics110may supply electrical power to the aircraft motor108. The aircraft motor108may turn a motor shaft204. A mounting plate220may connect an inner hub226of the axial fan104to the motor shaft204via suitable fasteners, which include but are not limited to screws, bolts, rivets, or other mechanical or chemical fasteners. Motion of the motor shaft204may cause the axial fan104to produce the airflow214through the annulus206. In some examples, the inner hub226of the axial fan104may be integrally formed with the spinner cone102. While not shown, the motor shaft204may also be used to turn a propeller of the fan-cooled motor system100.

FIG.3is a sectional view of a fan-cooled motor system300for cooling an electrical aircraft motor, according at least one example. The fan-cooled motor system300is an alternative example of the fan-cooled motor system100described herein. The axial fan307is an alternative example of the axial fan104described herein. The motor shaft304is an alternative example of the motor shaft204described herein. The present example may differ from the example illustrated inFIG.2because the axial fan307is not integrally formed with a propeller spinner. As a result, the axial fan307may be directly installed on the motor shaft304, which may alter the position of the axial fan307relative to the motor shaft304and may alter the distance between the axial fan307and the aircraft motor108. An inner hub328of the axial fan307may have a first diameter322and an outer hub330of the axial fan307may have a second diameter324. The values of the diameters described with respect toFIG.2may be equally applicable to the diameters shown inFIG.3.

Blades308of the axial fan307may direct airflow312through an annulus306of the fan-cooled motor system300. The annulus306is an alternative example of the annulus206described herein. The airflow312may fluidly communicate with cooling fins111of the aircraft motor108and the power supply electronics110. The airflow312is an alternative example of the airflow214described herein. The axial fan307may be formed of materials including but not limited to aluminum, stainless steel, fiberglass, graphite fiber, nickel-aluminum-bronze alloy, manganese bronze alloy, other metallic materials, composite materials, or other similar materials. The sizes of the inner hub, the outer hub, the annulus306, and the fin shown inFIG.3may be similar configured those elements shown inFIG.2.

A mounting plate326may connect to an inner hub328of the axial fan307to the motor shaft304via suitable fasteners, which include but are not limited to screws, bolts, rivets, or other mechanical or chemical fasteners. The mounting plate326may also connect a narrow region of a propeller spinner cone to the motor shaft304. Motion of the motor shaft304may cause the axial fan307to produce the airflow312through the annulus306.

FIG.4is an isometric view of an axial fan104and a mounting plate220according to at least one example. The axial fan104is depicted with a spinner cone102, integral to the axial fan104, inFIG.1andFIG.2. An inner hub226of the axial fan104may have a first diameter222and an outer hub228may have a second diameter224. The outer hub228may be concentrically aligned with the inner hub226. The blades106of the axial fan104may extend between the inner hub226and the outer hub228. The outer hub228may reduce tip losses and may contribute to the structural integrity of the axial fan104. The mounting plate220may be integrally formed with the inner hub226and may extend radially from the center of the axial fan104to the first diameter222of the inner hub226. The outer hub228of the axial fan104may comprise a ring of uniform thickness characterized by the second diameter224as an inner ring and a fifth diameter of some thickness as an outer ring. The inner hub226of the axial fan104may be connected to the outer hub228of the axial fan104by the plurality of blades106between the inner hub226and the outer hub228. The root of each of the blades106may be connected to the inner hub226and the tip of each blade may be connected to the outer hub228.

The mounting plate220may be connected to a motor shaft, such as the motor shaft204ofFIG.2. The mounting plate220may be connected by suitable fasteners, which include but are not limited to screws, bolts, rivets, or other mechanical or chemical fasteners. A motor shaft may connect to the mounting plate220at a shaft opening402. Inserts404for connecting the mounting plate220to the axial fan104may be threaded or smooth, depending on the mode of attachment. In an alternative example, a mounting plate similar to the mounting plate326ofFIG.3may connect an axial fan307, without an integrally attached propeller spinner, to a motor shaft. The mounting plate220may be further defined by weight relief features406, which may reduce rotational inertia, thus reducing power loss.

The first diameter222may correspond to a third diameter of the aircraft motor108and the second diameter224may correspond to a fourth diameter of the aircraft motor108. The radial distance between the first diameter222and the second diameter224may be about equal to the radial distance between the third diameter of the aircraft motor108and the fourth diameter of the aircraft motor108.

FIG.5is an isometric view of an electrical aircraft motor103and a set of cooling fins504according to at least on example. The set of cooling fins504is an example of the cooling fins111. The electrical aircraft motor103may be encompassed by the cooling fins504. Power supply electronics, such as the power supply electronics110ofFIG.1andFIG.2, may include similar cooling fins, such as cooling fins111. The cooling fins504may be encompassed by a cowl502. A third diameter522, which in some examples may be roughly equal to the first diameter222, may correspond to the body of the electrical aircraft motor103. A fourth diameter524, which in some examples may be roughly equal to the second diameter224, may correspond to the diameter of the cowl502. The radial distance between the third diameter522and the fourth diameter524may be of roughly equal height as the cooling fins504that extend from the body of the electrical aircraft motor103toward the cowl502. Airflow may pass through an annulus506, defined by the difference between the fourth diameter524and the third diameter522.

FIG.6is a top view of a blade602of an axial fan according to at least one example. The blade602may be formed of materials including but not limited to aluminum, stainless steel, fiberglass, graphite fiber, nickel-aluminum-bronze alloy, manganese bronze alloy, other metallic materials, composite materials, or other suitable similar materials. The root608of the blade may be connected to an inner hub of the axial fan and the tip610of the blade may be connected to an outer hub of the axial fan. The blade602may taper from the root608of the blade to the tip610of the blade. The blade602may be one of a plurality of blades, between seven and thirty, and may be characterized by a root angle604between 25 and 75 degrees. The blade602may also be characterized by a tip angle606between 25 and 75 degrees. The difference between the root angle604and the tip angle606may define a twist of the blade602. Other configurations are also possible. The blade twist, blade thickness, and blade angle may be varied according to the rotational speed of the application in order to maintain aerodynamic flow with minimal flow separation in order to keep energy losses low. The twist may be adjusted, based on the engine for which they are paired, to maintain aerodynamic flow with minimal flow separation.

In the following, further examples are described to facilitate the understanding of the disclosure:Example A. A fan assembly for an electrical aircraft motor, comprising: an axial fan comprising: an inner hub having a first diameter; an outer hub having a second diameter and being concentrically aligned with the inner hub; and a plurality of blades extending between the inner hub and the outer hub; and a mounting plate connected to the inner hub and configured for mounting the fan assembly to a component of the electrical aircraft motor, wherein the first diameter corresponds to a third diameter of the electrical aircraft motor and the second diameter corresponds a fourth diameter of the electrical aircraft motor.Example B. The fan assembly of any preceding or subsequent examples, wherein a first radial distance measured between the first diameter and the second diameter is about equal to a second radial distance measured between the third diameter and the fourth diameter.Example C. The fan assembly of any preceding or subsequent examples, wherein the third diameter corresponds to a body of the electrical aircraft motor and the fourth diameter corresponds to a cowl of the electrical aircraft motor.Example D. The fan assembly of any preceding or subsequent examples, wherein a radial distance between the third diameter and the fourth diameter is about equal to a height of a set of cooling fins that extend radially from the body of the electrical aircraft motor toward the cowl.Example E. The fan assembly of any preceding or subsequent examples, wherein a radial distance between the third diameter and the fourth diameter is about equal to a height of a set of cooling fins that extend radially from a body of the electrical aircraft motor.Example F. The fan assembly of any preceding or subsequent examples, wherein the component comprises at least one of a motor shaft of the electrical aircraft motor or a propeller.Example G. The fan assembly of any preceding or subsequent examples, wherein the inner hub is integrally formed with a propeller spinner.Example H. The fan assembly of any preceding or subsequent examples, wherein the plurality of blades comprises a number between seven and thirty.Example I. The fan assembly of any preceding or subsequent examples, wherein a root of each blade of the plurality of blades is connected to the inner hub and a tip of each blade of the plurality of blades is connected to the outer hub.Example J. The fan assembly of any preceding or subsequent examples, wherein each blade of the plurality of blades is characterized by a root angle and a tip angle between 25 degrees and 75 degrees.Example K. The fan assembly of any preceding or subsequent examples, further comprising a cone concentrically aligned with and connected to the inner hub.Example L. The fan assembly of any preceding or subsequent examples, wherein an annulus region of the cone is between 5 mm and 50 mm wide.Example M. The fan assembly of any preceding or subsequent examples, wherein the mounting plate is integrally formed with the inner hub and extends radially from a center of the axial fan to the first diameter of the inner hub.Example N. The fan assembly of any preceding or subsequent examples, wherein the outer hub comprises a ring of uniform thickness characterized by the second diameter as an inner ring diameter and a fifth diameter as an outer ring diameter.Example O. The fan assembly of any preceding or subsequent examples, wherein the inner hub is connected to the outer hub via the plurality of blades.Example P. A system, comprising: an electrical aircraft motor comprising an annular body and a set of cooling fins extending from the annular body; and an axial fan connected to the electrical aircraft motor, the axial fan comprising: an inner hub having a first diameter corresponding to the annular body; an outer hub having a second diameter and being concentrically aligned with the inner hub, wherein the second diameter corresponds to the set of cooling fins; and a plurality of blades extending between the inner hub and the outer hub.Example Q. The system of any preceding or subsequent examples, wherein the electrical aircraft motor further comprises an annular cowl that surrounds the set of cooling fins, wherein a first radial distance between the first diameter and the second diameter is about equal a second radial distance between the annular body and the annular cowls.Example R. The system of any preceding or subsequent examples, wherein the axial fan is connected to the electrical aircraft motor via a motor shaft of the electrical aircraft motor or via a propeller that is connected to the motor shaft.Example S. A system, comprising: an electrical aircraft motor housing comprising: a first annular housing that includes an electrical motor; a second housing that includes control electronics; and a motor shaft that is rotatably connected to the electrical motor; and an axial fan connected to the motor shaft, the axial fan comprising: an inner hub having a first diameter corresponding to the first annular housing; an outer hub having a second diameter and being concentrically aligned with the inner hub, wherein the second diameter is greater than the first diameter; and a plurality of blades extending between the inner hub and the outer hub.Example T. The system of any preceding or subsequent examples, further comprising a propeller, and wherein the axial fan is connected to the motor shaft via the propeller.

Use herein of the word “or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and all three of A, B, and C.