WO2021123707A1

WO2021123707A1 - A contra-rotating fan drive assembly

Info

Publication number: WO2021123707A1
Application number: PCT/GB2020/052426
Authority: WO
Inventors: Artem MARIE-MAGDELEINE; Hashanka THILAKAWARDHANA; Robert Fryer
Original assignee: Dyson Technology Limited
Priority date: 2019-12-20
Filing date: 2020-10-02
Publication date: 2021-06-24
Also published as: CN214756007U; CN113014052A; GB201919012D0; GB2590630B; GB2590630A

Abstract

According to an aspect of the invention there is provided a contra-rotating drive assembly comprising a first impeller, a second impeller, and a contra-rotating electric motor. The contra-rotating electric motor comprises a driveshaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the driveshaft, and the outer rotor is arranged to rotate relative to the driveshaft. The first impeller is fixedly connected to the driveshaft for rotation therewith, and the second impeller is fixedly connected to the outer rotor for rotation therewith. The contra-rotating electric motor comprises a battery that is fixed relative to a first of the inner rotor and the outer rotor for rotation therewith, the battery being arranged to provide an electric current to the first of the inner rotor and the outer rotor and thereby cause the inner rotor and the outer rotor to rotate in opposite directions.

Description

A CONTRA-ROTATING FAN DRIVE ASSEMBLY

Technical field

The present invention relates to a contra-rotating fan drive assembly and to a fan assembly comprising the contra-rotating fan drive assembly.

Background

Conventional domestic and industrial fans typically include an impeller comprising a set of blades mounted for rotation about an axis, together with a drive assembly for rotating the impeller to generate an air flow. The movement and circulation of the air flow creates a breeze and, as a result, a user or device experiences a cooling effect as heat is dissipated through convection and evaporation. The rotation of the blades exerts a tangential or rotational component on the direction of the air flowing through the impeller. This not only reduces the mass flow through the fan and increases energy losses, but also exerts torque or turning force acting on the fan. It is known that these drawbacks can be offset by using two coaxial impellers arranged to rotate in opposite directions, often termed a contra-rotating fan. The rotation of the downstream impeller in this arrangement cancels the rotational component applied to the air flowing through the upstream impeller, maximising mass flow through the fan and minimising energy losses. The torque acting on the fan is also effectively cancelled out due contra-rotating impellers. However, contra-rotating impellers are not widely used in domestic or industrial fans, partly due to their expense, but also due to the fact that occupy more space when compared to fan comprising a single impeller.

Existing contra-rotating fans use either two independent motors to drive the impellers, or one single motor coupled to a gear set arranged to drive the two impellers in opposite directions. Such arrangements are expensive and cumbersome to package. In addition, the use of gears causes noise and adds inefficiencies into the system.

It has been proposed to use a contra-rotating motor supplied with electricity via contactless power transmission to drive the contra-rotating impellers. However, such a power supply is expensive and has limited capacity.

The aim of this invention is to mitigate some of the drawbacks associated with contra-rotating fans.

Summary of the invention

The contra-rotating electric motor may comprise a motor controller that is fixed relative to the battery for rotation therewith, the motor controller being arranged to receive the electric current from the battery and to control the provision of the electric current to the first of the inner rotor and the outer rotor.

The contra-rotating electric motor may comprise a motor mounting assembly, and the driveshaft may then be rotationally mounted to the motor mounting assembly. A first end of the driveshaft may be rotationally mounted to the motor mounting assembly and the first impeller fixedly connected to an opposite, second end of the driveshaft. The inner rotor may be disposed between the first end and the second end of the driveshaft.

The outer rotor may be disposed concentrically around the inner rotor. The outer rotor may comprise a rotor housing, with the rotor housing being rotationally mounted to the driveshaft and the second impeller fixedly connected to the rotor housing. The battery may be fixedly connected to the rotor housing. The motor controller may be fixedly connected to the rotor housing.

The inner rotor may comprise a permanent magnet and the outer rotor an electromagnet. Alternatively, the inner rotor may comprise an electromagnet and the outer rotor a permanent magnet.

According to another aspect of the invention there is provided a contra-rotating drive assembly comprising a first set of blades, a second of blades, and a contra-rotating electric motor. The contrarotating electric motor comprises a driveshaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the driveshaft, and the outer rotor is arranged to rotate relative to the driveshaft. The first set of blades is fixedly connected to the driveshaft for rotation therewith, and the second set of blades is fixedly connected to the outer rotor for rotation therewith. The contra-rotating electric motor comprises a battery that is fixed relative to a first of the inner rotor and the outer rotor for rotation therewith, the battery being arranged to provide an electric current to the first of the inner rotor and the outer rotor and thereby cause the inner rotor and the outer rotor to rotate in opposite directions.

There is also provided a contra-rotating fan drive assembly comprising a first impeller, a second impeller, and a contra-rotating electric motor. The contra-rotating electric motor comprises a driveshaft, an inner rotor and an outer rotor, wherein the inner rotor is fixedly connected to the driveshaft and the outer rotor is arranged to rotate relative to the driveshaft. The first impeller is fixedly connected to the driveshaft for rotation therewith, and the second impeller is fixedly connected to the outer rotor for rotation therewith. The contra-rotating electric motor comprises a motor controller that is fixed relative to a first of the inner rotor and the outer rotor for rotation therewith, the motor controller being arranged to provide an electric current to the first of the inner rotor and the outer rotor and thereby cause the inner rotor and the outer rotor to rotate in opposite directions.

The contra-rotating electric motor may comprise a motor mounting assembly, and the driveshaft rotationally may then be mounted to the motor mounting assembly. A first end of the driveshaft may be rotationally mounted to the motor mounting assembly and the first impeller fixedly connected to an opposite, second end of the driveshaft. The inner rotor may be disposed between the first end and the second end of the driveshaft.

The contra-rotating electric motor may comprise a sliding electrical contact assembly, the motor controller being arranged to receive the electric current via the sliding electrical contact assembly and to control the provision of the electric current to the first of the inner rotor and the outer rotor. The sliding electrical contact assembly may comprise a stationary part that is fixedly connected to the motor mounting assembly and a rotatable part that is fixedly connected to the first of the inner rotor and the outer rotor for rotation therewith, the stationary part being in electrical contact with the rotatable part.

The outer rotor may be disposed concentrically around the inner rotor. The outer rotor may comprise a rotor housing, with the rotor housing being rotationally mounted to the driveshaft and the second impeller fixedly connected to the rotor housing. The motor controller may be fixedly connected to the rotor housing.

There is also provided a contra-rotating drive assembly comprising a first set of blades, a second set of blades, and a contra-rotating electric motor. The contra-rotating electric motor comprises a driveshaft, an inner rotor and an outer rotor, wherein the inner rotor is fixedly connected to the driveshaft and the outer rotor is arranged to rotate relative to the driveshaft. The first set of blades is fixedly connected to the driveshaft for rotation therewith, and the second set of blades is fixedly connected to the outer rotor for rotation therewith. The contra-rotating electric motor further comprises a motor controller that is fixed relative to a first of the inner rotor and the outer rotor for rotation therewith, the motor controller being arranged to provide an electric current to the first of the inner rotor and the outer rotor and thereby cause the inner rotor and the outer rotor to rotate in opposite directions. Brief description of the drawings

The present invention will now be described by way of non-limiting examples with reference to the following figures, in which:

Figure 1 shows a schematic view of a first arrangement of a contra-rotating fan drive assembly,

Figure 2 shows a schematic view of a second arrangement for a contra-rotating fan drive assembly, and

Figure 3 shows a schematic view of a third arrangement for a contra-rotating fan drive assembly.

Detailed description

Figure 1 shows a schematic representation of a first arrangement of a contra-rotating fan drive assembly 100. The contra-rotating fan drive assembly 100 comprises a first impeller 101 , a second impeller 102 and a contra-rotating electric motor 103. The contra-rotating electric motor 103 then comprises a driveshaft 104, an inner rotor 105, and an outer rotor 106. The inner rotor 105 is fixedly connected to the driveshaft 104 whilst the outer rotor 106 is arranged to rotate relative to the driveshaft 104. The first impeller 101 is then fixedly connected to the driveshaft 104 for rotation therewith, and the second impeller 102 is fixedly connected to the outer rotor 106 for rotation therewith. The contra-rotating electric motor 103 then further comprises a motor controller 107 that is configured to control the electric motor 103 by controlling the provision of an electric current to one of the inner rotor 105 and the outer rotor 106. In particular, the motor controller 107 is arranged to provide electronic commutation for the electric motor 103 and to control the speed of the electric motor 103.

In the arrangement illustrated in Figure 1 , the outer rotor 106 comprises an electromagnet 108 whilst the inner rotor 105 comprises a permanent magnet 109. The motor controller 107 is then fixed relative to the outer rotor 106 such that it rotates with the outer rotor 106 when the drive assembly 100 is in use, and the motor controller 107 is in electrical contact with the outer rotor 106 in order to provide an electric current to the electromagnet 108. In use, the outer rotor 106 produces a magnetic field in response to an electric current received from the motor controller 107 with the resulting magnetic interaction between outer rotor 106 and the inner rotor 105 then causing the inner rotor 106 and the outer rotor 105 to rotate in opposite directions due to the = principle of conservation of angular momentum. The inner rotor 105 can therefore be considered to be substantially the same as the rotor of a conventional electric motor, whilst the outer rotor 106 can be considered to be a rotatably mounted stator. Therefore, in use, the first impeller 101 rotates in a first direction with the driveshaft 104 and the inner rotor 105, whilst the second impeller 102 rotates in an opposite, second direction with the outer rotor 106.

The contra-rotating electric motor 103 also comprises a motor mounting assembly 110 that is arranged to support the contra-rotating electric motor 103 and to allow the contra-rotating electric motor 103 to be mounted or fixed to another object. The driveshaft 104 is therefore rotationally mounted to the motor mounting assembly 110 by way of a plurality of bearings 111. In particular, a first end of the driveshaft 104 is rotationally mounted to the motor mounting assembly 110 whilst the first impeller 101 is fixedly connected to an opposite, second end of the driveshaft 104. The inner rotor 105 is then disposed between the first end and the second end of the driveshaft 104.

In the arrangement illustrated in Figure 1 , the outer rotor 106 comprises a rotor housing 112 that is rotationally mounted to the driveshaft 104 by way of a plurality of bearings 113, with the electromagnet 108 being fixedly connected to or mounted within the rotor housing 112 and the motor controller 107 being fixedly connected or attached to the rotor housing 112. The second impeller 102 is then fixedly connected to the exterior of the rotor housing 112. The contra-rotating electric motor 103 is then provided with a sliding electrical contact assembly through which electrical power is provided to the motor controller 107. The sliding electrical contact assembly comprises a stationary part 114 that is fixedly connected to the motor mounting assembly 110 and a rotatable part 115 that is fixedly connected to the outer rotor 106, the stationary part 114 being in electrical contact with the rotatable part 115. For example, the stationary part 114 could comprise one or more electrical contact brushes whilst the rotatable part 115 could comprise one or more conductive rings or traces that are contacted by the brushes. The stationary part 214 would then be arranged to receive electrical power from a power source (not shown).

In the specific arrangement illustrated in Figure 1 , the drive assembly 100 further comprises a main housing 120 that forms a duct 121 defining an annular air flow path that extends through the drive assembly 100. The duct 121 is arranged such that its longitudinal axis is collinear with a rotational axis (X) of the contra-rotating fan drive assembly 100. The duct 121 comprises a first end defining an annular air inlet 122, through which drive assembly 100 is configured to draw air into the duct 121 , and a second end located opposite to the first end and defining an annular air outlet 123, where air that has been worked by drive assembly 100 is emitted from the duct 121 . The annular air flow path is then disposed between an inner surface of the main housing 120 and a radially outer surface of a hub or rear shroud of each of the first and second impellers 101 , 102, together with a radially outer surface of an inner portion 124 of the main housing 120 which sits adjacent the second impeller 102. The motor mounting assembly 110 is then attached to the inner portion 124 of the main housing 120 such that the first impeller 101 , the second impeller 102 and the contra-rotating electric motor 103 are supported coaxially within the duct 121. The first impeller 101 then also comprises a cap 116 for directing oncoming air towards the annular air inlet 122, whilst an outer surface of the inner portion 124 of the main housing 120 carries a stator cap 125, which is shaped ensure that the air flows smoothly out from the annular air outlet 123.

Figure 2 shows a schematic view of a second arrangement of a contra-rotating fan drive assembly 200. The contra-rotating fan drive assembly 200 of Figure 2 comprises a first impeller 201 , a second impeller 202 and a contra-rotating electric motor 203. The contra-rotating electric motor 203 then comprises a driveshaft 204, an inner rotor 205, and an outer rotor 206. The inner rotor 205 is fixedly connected to the driveshaft 204 and the outer rotor 206 is arranged to rotate relative to the driveshaft 204. The first impeller 201 is then fixedly connected to the driveshaft 204 for rotation therewith, and the second impeller 202 is fixedly connected to the outer rotor 206 for rotation therewith. The contrarotating electric motor 203 then further comprises a motor controller 207 that is configured to control the electric motor 203 by controlling the provision of an electric current to one of the inner rotor 205 and the outer rotor 206. In particular, the motor controller 207 is arranged to provide electronic commutation for the electric motor 203 and to control the speed of the electric motor 203.

In the arrangement illustrated in Figure 2, the inner rotor 205 comprises an electromagnet 208 whilst the outer rotor 206 comprises a permanent magnet 209. The motor controller 207 is then fixed relative to the inner rotor 205 such that it rotates with the inner rotor 205 when the drive assembly is in use, and the motor controller 207 is in electrical contact with the inner rotor 205 in order to provide an electric current to the electromagnet 208. In use, the inner rotor 205 produces a magnetic field in response to an electric current received from the motor controller 207 with the resulting magnetic interaction between inner rotor 205 and the outer rotor 206 then causing the inner rotor 205 and the outer rotor 206 to rotate in opposite directions due to the principle of conservation of angular momentum. The outer rotor 206 can therefore be considered to be substantially the same as the rotor of a conventional electric motor, whilst the inner rotor 205 can be considered to be a rotatably mounted stator. Therefore, in use, the first impeller 201 rotates in a first direction with the driveshaft

204 and the inner rotor 205, whilst the second impeller 202 rotates in an opposite, second direction with the outer rotor 206.

The contra-rotating electric motor 203 also comprises a motor mounting assembly 210 that is arranged to support the contra-rotating electric motor 203 and to allow the contra-rotating electric motor 203 to be mounted/fixed to another object. The driveshaft 204 is therefore rotationally mounted to the motor mounting assembly 210 by way of a plurality of bearings 211. In particular, a first end of the driveshaft 204 is rotationally mounted to the motor mounting assembly 210 whilst the first impeller 201 is fixedly connected to an opposite, second end of the driveshaft 204. The inner rotor 205 is then disposed between the first end and the second end of the driveshaft 204.

In the arrangement illustrated in Figure 2, the outer rotor 206 comprises a rotor housing 212 that is rotationally mounted to the driveshaft 204 by way of a plurality of bearings 213, with the second impeller 202 fixedly connected or mounted on to the exterior of the rotor housing 212. The inner rotor

205 then comprises a support 216 that is fixedly connected to the driveshaft 204, with the motor controller 207 fixedly connected or mounted to the support 216. The contra-rotating electric motor 203 is then provided with a sliding electrical contact assembly through which electrical power is provided to the motor controller 207. The sliding electrical contact assembly comprises a stationary part 214 that is fixedly connected to the motor mounting assembly 210, and a rotatable part 215 that is fixedly connected to the inner rotor 205, the stationary part 214 being in electrical contact with the rotatable part 215. For example, the stationary part 214 could comprise one or more electrical contact brushes whilst the rotatable part 215 could comprise one or more conductive rings or traces that are contacted by the brushes. The stationary part 214 would then be arranged to receive electrical power from a power source (not shown).

In the specific arrangement illustrated in Figure 2, the drive assembly 200 further comprises a main housing 220 that forms a duct 221 defining an annular air flow path that extends through the drive assembly 200. The duct 221 is arranged such that its longitudinal axis is collinear with a rotational axis (X) of the contra-rotating fan drive assembly 200. The duct 221 comprises a first end defining an annular air inlet 222, through which drive assembly 200 is configured to draw air into the duct 221 , and a second end located opposite to the first end and defining an annular air outlet 223, where air that has been worked by drive assembly 200 is emitted from the duct 221 . The annular air flow path is then disposed between an inner surface of the main housing 220 and a radially outer surface of a hub or rear shroud of each of the first and second impellers 201 , 202, together with a radially outer surface of an inner portion 224 of the main housing 120 which sits adjacent the second impeller 202. The motor mounting assembly 210 is then attached to the inner portion 224 of the main housing 220 such that the first impeller 201 , the second impeller 202 and the contra-rotating electric motor 203 are supported coaxially within the duct 221. The first impeller 201 then also comprises a cap 217 for directing oncoming air towards the annular air inlet 222, whilst an outer surface of the inner portion 224 of the main housing 220 carries a stator cap 225, which is shaped ensure that the air flows smoothly out from the annular air outlet 223.

Figure 3 then shows a schematic view of a third arrangement for a contra-rotating fan drive assembly 100a. This third arrangement is similar to that of the first arrangement and corresponding reference numerals have therefore been used for like or corresponding parts or features of these arrangements. The only significant difference between the first arrangement and the third arrangement is that the contra-rotating electric motor 103 of the third arrangement further comprises an on-board battery 130 that is arranged to provide an electric current for energizing the motor 103. Specifically, the battery 130 is fixed relative to the motor controller 107 for rotation therewith and is in electrical contact with the motor controller 107 in order to provide an electric current to the motor controller 107. In use, the motor controller 107 then controls the provision of the electric current received from the battery 130 to one of the inner rotor 105 and the outer rotor 106. The inclusion of an on-board battery 130 within the contra-rotating fan drive assembly 100a provides that the contra-rotating fan drive assembly 100a may be operated when disconnected from any external power supply, and is therefore suitable for use in portable devices.

The contra-rotating fan drive assembly 100a is then arranged to allow for the battery 130 to be recharged when not in use. In the arrangement of Figure 3, the contra-rotating electric motor 103 is provided with a sliding electrical contact assembly 114, 115 through which electrical power can be provided in order to recharge the battery 130. However, in alternative arrangements the recharging of the battery 130 could be achieved using other means, such as wireless power transmission. In the arrangement of Figure 3, the outer rotor 106 comprises an electromagnet 108 whilst the inner rotor 105 comprises a permanent magnet 109, such that both the battery 120 and the motor controller 107 are then fixed relative to the outer rotor 106 such that they rotate with the outer rotor 106. However, in a yet further arrangement the contra-rotating fan drive assembly could be substantially the same as that of the second arrangement in which the inner rotor 205 comprises an electromagnet 208 such that both the battery and the motor controller would then be fixed relative to the inner rotor 205 such that they rotate with the inner rotor 205.

It will be appreciated by those skilled in the art that the invention has been described by way of example only, and that a variety of alternative approaches or modifications may be adopted without departing from the scope of the invention as defined by the appended claims. For example, the above described embodiments each relate to a contra-rotating drive assembly for driving a fan and therefore comprise first and second contra-rotating impellers, wherein an impeller is a rotating part of a machine that is designed to move a fluid. However, those skilled in the art will appreciate that the above- described contra-rotating drive assembly could equally be used to drive contra-rotating propellers for generating thrust.

By way of example, in the arrangement of Figure 3 the battery is located concentrically around the electromagnet. However, this is not essential. In particular, the battery could be located such that the electromagnet is disposed concentrically around the battery. Alternatively, the battery could be located to one side of the electromagnet such that the battery is disposed either closer to the first end of the driveshaft than the electromagnet (e.g. between the electromagnet and the motor mounting assembly) or closer to the second end of the driveshaft then the electromagnet (e.g. between the electromagnet and the first impeller). In addition, the contra-rotating fan drive assembly could comprise a plurality of batteries that are arranged to cooperate to provide an electric current for energizing the motor. The plurality of batteries would then be distributed around the electromagnet. For example, a plurality of batteries could be distributed circumferentially around the outside of the electromagnet and/or to one side of the electromagnet.

Claims

1. A contra-rotating fan drive assembly comprising: a first impeller; a second impeller; and a contra-rotating electric motor comprising a driveshaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the driveshaft, and the outer rotor is arranged to rotate relative to the driveshaft; wherein the first impeller is fixedly connected to the driveshaft for rotation therewith, and the second impeller is fixedly connected to the outer rotor for rotation therewith; and wherein the contra-rotating electric motor comprises a battery that is fixed relative to a first of the inner rotor and the outer rotor for rotation therewith, the battery being arranged to provide an electric current to the first of the inner rotor and the outer rotor and thereby cause the inner rotor and the outer rotor to rotate in opposite directions..

2. The contra-rotating fan drive assembly of claim 1 , wherein the contra-rotating electric motor comprises a motor controller that is fixed relative to the battery for rotation therewith, the motor controller being arranged to receive the electric current from the battery and to control the provision of the electric current to the first of the inner rotor and the outer rotor.

3. The contra-rotating fan drive assembly of any one or claims 1 to 2, wherein the contra-rotating electric motor comprises a motor mounting assembly, and the driveshaft is rotationally mounted to the motor mounting assembly.

4. The contra-rotating fan drive assembly of claim 3, wherein a first end of the driveshaft is rotationally mounted to the motor mounting assembly and the first impeller is fixedly connected to an opposite, second end of the driveshaft.

5. The contra-rotating fan drive assembly of claim 54 wherein the inner rotor is disposed between the first end and the second end of the driveshaft.

6. The contra-rotating fan drive assembly of any one of claims 1 to 5, wherein the outer rotor is disposed concentrically around the inner rotor.

7. The contra-rotating fan drive assembly of any one of claims 1 to 6, wherein the outer rotor comprises a rotor housing, with the rotor housing being rotationally mounted to the driveshaft, and the second impeller is fixedly connected to the rotor housing.

8. The contra-rotating fan drive assembly of claim 7, wherein the battery is fixedly connected to the rotor housing.

9. The contra-rotating fan drive assembly of claim 8, wherein the motor controller is fixedly connected to the rotor housing.

10. The contra-rotating fan drive assembly of any one of claims 1 to 9, wherein the inner rotor comprises a permanent magnet and the outer rotor comprises an electromagnet.

11 . The contra-rotating fan drive assembly of any one of claims 1 to 9, wherein the inner rotor comprises an electromagnet and the outer rotor comprises a permanent magnet. 13. A contra-rotating drive assembly comprising: a first set of blades; a second of blades; and a contra-rotating electric motor comprising a driveshaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the driveshaft, and the outer rotor is arranged to rotate relative to the driveshaft; wherein the first set of blades is fixedly connected to the driveshaft for rotation therewith, and the second set of blades is fixedly connected to the outer rotor for rotation therewith; and wherein the contra-rotating electric motor comprises a battery that is fixed relative to a first of the inner rotor and the outer rotor for rotation therewith, the battery being arranged to provide an electric current to the first of the inner rotor and the outer rotor and thereby cause the inner rotor and the outer rotor to rotate in opposite directions.