Fan drive assembly

Abstract

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

Description

Technical Field

[0001] The present invention relates to a counter-rotating fan drive assembly and to a fan assembly including the counter-rotating fan drive assembly. Background Art

[0002] Traditional household and industrial fans typically include an impeller, consisting of a set of blades mounted for rotation about an axis, and a drive assembly for rotating the impeller to generate airflow. The impeller, which consists of a set of blades mounted for rotation about an axis, creates a breeze. As a result, the user or device dissipates heat through convection and evaporation, achieving a cooling effect. The rotation of the blades imparts a tangential, or rotational, component to the direction of air flowing through the impeller. This not only reduces the mass flow through the fan and increases energy losses, but also applies a torque, or turning force, to the fan. It is well known that these limitations can be mitigated by using two coaxial impellers (commonly known as counter-rotating fans) rotating in opposite directions. In this arrangement, the rotation of the downstream impeller cancels the rotational component imparted to the air flowing through the upstream impeller, thereby maximizing mass flow through the fan and minimizing energy losses. Due to the counter-rotating impellers, torque acting on the fan is also effectively canceled. However, counter-rotating impellers are not widely used in household or industrial fans, partly due to their cost but also because they take up more space than fans with a single impeller.

[0003] Existing counter-rotating fans use two separate motors to drive the impellers, or a single motor coupled to a gear train that drives the two impellers in opposite directions. This arrangement is expensive and cumbersome to package. Furthermore, the use of gears can cause noise and increase system inefficiency.

[0004] It has been proposed to use a counter-rotating motor powered by contactless power transmission to drive the counter-rotating impellers. However, such power supplies are expensive and have limited capacity.

[0005] An object of the present invention is to alleviate some of the disadvantages associated with counter-rotating fans. Summary of the Invention

[0006] According to one aspect of the present invention, a counter-rotating drive assembly is provided, comprising a first impeller, a second impeller, and a counter-rotating electric motor. The counter-rotating electric motor comprises a drive shaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the drive shaft and the outer rotor is arranged to rotate relative to the drive shaft. The first impeller is fixedly connected to the drive shaft for rotation therewith, and the second impeller is fixedly connected to the outer rotor for rotation therewith. The counter-rotating electric motor comprises a battery fixed relative to a first rotor of the inner rotor and the outer rotor for rotation therewith, the battery being arranged to provide current to the first rotor of the inner rotor and the outer rotor, thereby causing the inner rotor and the outer rotor to rotate in opposite directions.

[0007] The contra-rotating electric motor may include a motor controller fixed relative to the battery for rotation therewith, the motor controller being arranged to receive current from the battery and control the supply of current to a first rotor of the inner and outer rotors.

[0008] The contra-rotating electric motor may include a motor mounting assembly to which a drive shaft may be rotatably mounted. A first end of the drive shaft may be rotatably mounted to the motor mounting assembly, while the first impeller may be fixedly coupled to an opposite second end of the drive shaft. The inner rotor may be disposed between the first and second ends of the drive shaft.

[0009] The outer rotor may be concentrically arranged around the inner rotor. The outer rotor includes a rotor housing rotatably mounted to the drive shaft, and the second impeller is fixedly connected to the rotor housing. A battery may be fixedly connected to the rotor housing. A motor controller may be fixedly connected to the rotor housing.

[0010] The inner rotor may comprise permanent magnets and the outer rotor may comprise electromagnets. Alternatively, the inner rotor may comprise electromagnets and the outer rotor may comprise permanent magnets.

[0011] According to another aspect of the present invention, a counter-rotating drive assembly is provided, comprising a first set of blades, a second set of blades, and a counter-rotating electric motor. The counter-rotating electric motor comprises a drive shaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the drive shaft and the outer rotor is arranged to rotate relative to the drive shaft. The first set of blades is fixedly connected to the drive shaft for rotation therewith, and the second set of blades is fixedly connected to the outer rotor for rotation therewith. The counter-rotating electric motor comprises a battery fixed relative to a first rotor of the inner rotor and the outer rotor for rotation therewith, the battery being arranged to provide current to the first rotor of the inner rotor and the outer rotor, thereby causing the inner rotor and the outer rotor to rotate in opposite directions.

[0012] A counter-rotating fan drive assembly is provided, comprising a first impeller, a second impeller, and a counter-rotating electric motor. The counter-rotating electric motor comprises a drive shaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the drive shaft and the outer rotor is arranged to rotate relative to the drive shaft. The first impeller is fixedly connected to the drive shaft for rotation therewith, while the second impeller is fixedly connected to the outer rotor for rotation therewith. The counter-rotating electric motor comprises a motor controller fixed relative to a first rotor of the inner and outer rotors for rotation therewith, the motor controller being arranged to provide current to the first rotor of the inner and outer rotors, thereby causing the inner and outer rotors to rotate in opposite directions.

[0013] The contra-rotating electric motor may include a motor mounting assembly to which a drive shaft may be rotatably mounted. A first end of the drive shaft may be rotatably mounted to the motor mounting assembly, while the first impeller may be fixedly coupled to an opposite second end of the drive shaft. The inner rotor may be disposed between the first and second ends of the drive shaft.

[0014] The contra-rotating electric motor includes a sliding electrical contact assembly, wherein the motor controller is configured to receive current via the sliding electrical contact assembly and control the supply of current to the first of the inner and outer rotors. The sliding electrical contact assembly includes a fixed portion fixedly connected to the motor mount assembly, and a rotatable portion fixedly connected to the first of the inner and outer rotors for rotation therewith, the fixed portion being in electrical contact with the rotatable portion.

[0015] The outer rotor may be concentrically arranged around the inner rotor. The outer rotor includes a rotor housing rotatably mounted to the drive shaft, and the second impeller is fixedly connected to the rotor housing. The motor controller may be fixedly connected to the rotor housing.

[0016] The inner rotor may comprise permanent magnets and the outer rotor may comprise electromagnets. Alternatively, the inner rotor may comprise electromagnets and the outer rotor may comprise permanent magnets.

[0017] A counter-rotating drive assembly is also provided, comprising a first set of blades, a second set of blades, and a counter-rotating electric motor. The counter-rotating electric motor comprises a drive shaft, an inner rotor, and an outer rotor, wherein the inner rotor is fixedly connected to the drive shaft and the outer rotor is arranged to rotate relative to the drive shaft. The first set of blades is fixedly connected to the drive shaft for rotation therewith, and the second set of blades is fixedly connected to the outer rotor for rotation therewith. The counter-rotating electric motor also includes a motor controller fixed relative to a first rotor of the inner rotor and the outer rotor for rotation therewith, the motor controller being arranged to provide current to the first rotor of the inner rotor and the outer rotor, thereby causing the inner rotor and the outer rotor to rotate in opposite directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Examples of the invention will now be described by way of non-limiting examples with reference to the following drawings, in which:

[0019] Figure 1 shows a schematic diagram of a first arrangement of a counter-rotating fan drive assembly,

[0020] Figure 2 a schematic diagram showing a second arrangement for a counter-rotating fan drive assembly, and

[0021] Figure 3 A schematic diagram is shown of a third arrangement for a counter-rotating fan drive assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a first arrangement of a counter-rotating fan drive assembly 100 is shown. Counter-rotating fan drive assembly 100 includes a first impeller 101, a second impeller 102, and a counter-rotating electric motor 103. Counter-rotating electric motor 103 then includes a drive shaft 104, an inner rotor 105, and an outer rotor 106. Inner rotor 105 is fixedly connected to drive shaft 104, while outer rotor 106 is arranged to rotate relative to drive shaft 104. First impeller 101 is fixedly connected to drive shaft 104 for rotation therewith, and second impeller 102 is fixedly connected to outer rotor 106 for rotation therewith. Counter-rotating electric motor 103 then also includes a motor controller 107 configured to control electric motor 103 by controlling the current supplied to one of inner rotor 105 and outer rotor 106. In particular, motor controller 107 is arranged to provide electronic commutation to electric motor 103 and control the speed of electric motor 103.

[0024] exist Figure 1 In the illustrated arrangement, the outer rotor 106 includes electromagnets 108, while the inner rotor 105 includes permanent magnets 109. A motor controller 107 is fixed relative to the outer rotor 106 so that when the drive assembly 100 is in use, the motor controller 107 rotates with the outer rotor 106 and is in electrical contact with the outer rotor 106 to provide current to the electromagnets 108. In use, the outer rotor 106 generates a magnetic field in response to the current received from the motor controller 107, thereby generating a magnetic interaction between the outer rotor 106 and the inner rotor 105. This interaction then causes the inner rotor 106 and the outer rotor 105 to rotate in opposite directions due to the principle of conservation of angular momentum. Thus, the inner rotor 105 can be considered substantially similar to the rotor of a conventional electric motor, while the outer rotor 106 can be considered a rotatably mounted stator. Thus, in use, the first impeller 101 rotates in a first direction along with the drive shaft 104 and the inner rotor 105, while the second impeller 102 rotates in an opposite, second direction along with the outer rotor 106.

[0025] The contra-rotating electric motor 103 also includes a motor mounting assembly 110, which is arranged to support the contra-rotating electric motor 103 and allow the contra-rotating electric motor 103 to be mounted or secured to another object. Accordingly, the drive shaft 104 is rotatably mounted to the motor mounting assembly 110 via a plurality of bearings 111. Specifically, a first end of the drive shaft 104 is rotatably mounted to the motor mounting assembly 110, while the first impeller 101 is fixedly connected to the opposite second end of the drive shaft 104. The inner rotor 105 is then disposed between the first and second ends of the drive shaft 104.

[0026] exist Figure 1In the illustrated arrangement, outer rotor 106 includes a rotor housing 112 rotatably mounted to drive shaft 104 via a plurality of bearings 113, with electromagnet 108 fixedly connected to or mounted within rotor housing 112, and motor controller 107 fixedly connected to or attached to rotor housing 112. Second impeller 102 is then fixedly connected to the exterior of rotor housing 112. Contra-rotating electric motor 103 is then provided with a sliding electrical contact assembly through which power is provided to motor controller 107. The sliding electrical contact assembly includes a stationary portion 114 fixedly connected to motor mount assembly 110 and a rotatable portion 115 fixedly connected to outer rotor 106, with stationary portion 114 in electrical contact with rotatable portion 115. For example, stationary portion 114 may include one or more electrical contact brushes, while rotatable portion 115 may include one or more conductive rings or traces contacted by the brushes. Stationary portion 214 is then arranged to receive power from a power source (not shown).

[0027] exist Figure 1 In the particular arrangement shown, the drive assembly 100 further includes a main housing 120 that forms a duct 121 that defines an annular air flow path extending through the drive assembly 100. The duct 121 is arranged so that its longitudinal axis is co-linear with the axis of rotation (X) of the counter-rotating fan drive assembly 100. The duct 121 includes a first end defining an annular air inlet 122 through which the drive assembly 100 is configured to draw air into the duct 121, and a second end opposite the first end that defines an annular air outlet 123 at which air processed by the drive assembly 100 is discharged from the duct 121. The annular air flow path is then defined between the inner surface of the main housing 120 and the radially outer surface of the hub or back shroud of each of the first and second impellers 101, 102, as well as the radially outer surface of an interior 124 of the main housing 120 located adjacent the second impeller 102. The motor mounting assembly 110 is then attached to the interior 124 of the main housing 120 so that the first impeller 101, the second impeller 102, and the contra-rotating electric motor 103 are coaxially supported within the duct 121. The first impeller 101 then further includes a cover 116 for directing incoming air toward the annular air inlet 122, while the outer surface of the interior 124 of the main housing 120 carries a stator cover 125, the shape of which ensures smooth outflow of air from the annular air outlet 123.

[0028] Figure 2 A schematic diagram of a second arrangement of a counter-rotating fan drive assembly 200 is shown. Figure 2The counter-rotating fan drive assembly 200 includes a first impeller 201, a second impeller 202, and a counter-rotating electric motor 203. The counter-rotating electric motor 203 includes a drive shaft 204, an inner rotor 205, and an outer rotor 206. The inner rotor 205 is fixedly connected to the drive shaft 204, while the outer rotor 206 is arranged to rotate relative to the drive shaft 204. The first impeller 201 is fixedly connected to the drive shaft 204 for rotation therewith, and the second impeller 202 is fixedly connected to the outer rotor 206 for rotation therewith. The counter-rotating electric motor 203 also includes a motor controller 207, which is configured to control the electric motor 203 by controlling the current supplied to one of the inner rotor 205 and the outer rotor 206. In particular, the motor controller 207 is arranged to provide electronic commutation to the electric motor 203 and control the speed of the electric motor 203.

[0029] exist Figure 2 In the illustrated arrangement, the inner rotor 205 includes electromagnets 208, while the outer rotor 206 includes permanent magnets 209. A motor controller 207 is fixed relative to the inner rotor 205 so that when the drive assembly is in use, the motor controller 207 rotates with the inner rotor 205 and is in electrical contact with the inner rotor 205 to provide current to the electromagnets 208. In use, the inner rotor 205 generates a magnetic field in response to the current received from the motor controller 207, thereby generating a magnetic interaction between the inner rotor 205 and the outer rotor 206. This interaction then causes the inner and outer rotors 205, 206, to rotate in opposite directions due to the principle of conservation of angular momentum. Thus, the outer rotor 206 can be considered substantially similar to the rotor of a conventional electric motor, while the inner rotor 205 can be considered a rotatably mounted stator. Thus, in use, the first impeller 201 rotates in a first direction along with the drive shaft 204 and the inner rotor 205, while the second impeller 202 rotates in an opposite, second direction along with the outer rotor 206.

[0030] The contra-rotating electric motor 203 also includes a motor mounting assembly 210, which is arranged to support the contra-rotating electric motor 203 and allow the contra-rotating electric motor 203 to be mounted or secured to another object. Accordingly, the drive shaft 204 is rotatably mounted to the motor mounting assembly 210 via a plurality of bearings 211. Specifically, a first end of the drive shaft 204 is rotatably mounted to the motor mounting assembly 210, while the first impeller 201 is fixedly connected to the opposite second end of the drive shaft 204. The inner rotor 205 is then disposed between the first and second ends of the drive shaft 204.

[0031] exist Figure 2In the illustrated arrangement, outer rotor 206 includes a rotor housing 212 rotatably mounted to drive shaft 204 via a plurality of bearings 213, and second impeller 202 is fixedly connected to or mounted on the exterior of rotor housing 212. Inner rotor 205 then includes a support 216 fixedly connected to drive shaft 204, and motor controller 207 is fixedly connected to or mounted on support 216. Contra-rotating electric motor 203 is then provided with a sliding electrical contact assembly through which power is provided to motor controller 207. The sliding electrical contact assembly includes a stationary portion 214 fixedly connected to motor mount assembly 210 and a rotatable portion 215 fixedly connected to inner rotor 205, with stationary portion 214 in electrical contact with rotatable portion 215. For example, stationary portion 214 may include one or more electrical contact brushes, while rotatable portion 215 may include one or more conductive rings or traces contacted by the brushes. Stationary portion 214 is then arranged to receive power from a power source (not shown).

[0032] exist Figure 2 In the particular arrangement shown, the drive assembly 200 further includes a main housing 220 that forms a duct 221 that defines an annular air flow path extending through the drive assembly 200. The duct 221 is arranged so that its longitudinal axis is co-linear with the axis of rotation (X) of the counter-rotating fan drive assembly 200. The duct 221 includes a first end defining an annular air inlet 222 through which the drive assembly 200 is configured to draw air into the duct 221, and a second end opposite the first end that defines an annular air outlet 223 at which air processed by the drive assembly 200 is discharged from the duct 221. The annular air flow path is then defined between the inner surface of the main housing 220 and the radially outer surface of the hub or back shroud of each of the first and second impellers 201, 202, as well as the radially outer surface of an interior 224 of the main housing 120 located adjacent the second impeller 202. The motor mounting assembly 210 is then attached to the interior 224 of the main housing 220 so that the first impeller 201, the second impeller 202, and the counter-rotating electric motor 203 are coaxially supported within the duct 221. The first impeller 201 then further includes a cover 217 for directing incoming air toward the annular air inlet 222, while the outer surface of the interior 224 of the main housing 220 carries a stator cover 225, the shape of which ensures smooth outflow of air from the annular air outlet 223.

[0033] then, Figure 3A schematic diagram of a third arrangement for a counter-rotating fan drive assembly 100a is shown. The third arrangement is similar to that of the first arrangement, and accordingly corresponding reference numerals have been used for identical or corresponding components or features of these arrangements. The only significant difference between the first and third arrangements is that the counter-rotating electric motor 103 of the third arrangement further includes an onboard battery 130 that is arranged to provide current for powering the motor 103. Specifically, the battery 130 is fixed relative to the motor controller 107 so as to rotate therewith and is in electrical contact with the motor controller 107 so as to provide current to the motor controller 107. In use, the motor controller 107 controls the current received from the battery 130 to be provided to one of the inner rotor 105 and the outer rotor 106. The inclusion of the onboard battery 130 in the counter-rotating fan drive assembly 100a provides that the counter-rotating fan drive assembly 100a can be operated while disconnected from any external power source, thereby making it suitable for use in portable devices.

[0034] Next, the contra-rotating fan drive assembly 100a is arranged to allow the battery 130 to be charged when not in use. Figure 3 In the arrangement of , the contra-rotating electric motor 103 is provided with sliding electrical contact assemblies 114, 115 through which power can be provided to charge the battery 130. However, in alternative arrangements, other means such as wireless power transfer may be used to achieve recharging of the battery 130.

[0035] exist Figure 3 In the arrangement of FIG. 1 , the outer rotor 106 includes electromagnets 108 and the inner rotor 105 includes permanent magnets 109, such that both the battery 120 and the motor controller 107 are fixed relative to the outer rotor 106 so that they rotate with the outer rotor 106. However, in yet another arrangement, the contra-rotating fan drive assembly can be substantially the same as the second arrangement, wherein the inner rotor 205 includes electromagnets 208, such that both the battery and the motor controller are fixed relative to the inner rotor 205 so that they rotate with the inner rotor 205.

[0036] Those skilled in the art will recognize that the present invention has been described by way of example only and that various alternatives or modifications may be employed without departing from the scope of the invention as defined by the appended claims. For example, the above embodiments all relate to a counter-rotating drive assembly for driving a fan, and thus include a first counter-rotating impeller and a second counter-rotating impeller, wherein an impeller is a rotating component of a machine designed to move a fluid. However, those skilled in the art will understand that the above counter-rotating drive assembly can also be used to drive a counter-rotating propeller to generate thrust.

[0037] For example, in Figure 3In an arrangement, the batteries are positioned concentrically around the electromagnet. However, this is not required. In particular, the batteries can be positioned so that the electromagnet is arranged concentrically around the batteries. Alternatively, the batteries can be located on one side of the electromagnet so that the batteries are either closer to the first end of the drive shaft than the electromagnet (e.g., between the electromagnet and the motor mounting assembly) or closer to the second axis of the drive shaft than the electromagnet (e.g., between the electromagnet and the first impeller). In addition, the counter-rotating fan drive assembly may include a plurality of batteries that are arranged to cooperate to provide current for energizing the motor. The plurality of batteries are distributed around the electromagnet. For example, the plurality of batteries can be distributed circumferentially around the outside of the electromagnet and / or one side of the electromagnet.

Claims

1. A counter-rotating fan drive assembly, comprising: First impeller; Second impeller; and a contra-rotating electric motor comprising a drive shaft, an inner rotor and an outer rotor, wherein the inner rotor is fixedly connected to the drive shaft and the outer rotor is arranged to rotate relative to the drive shaft; wherein the first impeller is fixedly connected to the drive shaft for rotation therewith, and the second impeller is fixedly connected to the outer rotor for rotation therewith; and The counter-rotating electric motor includes a battery fixed relative to a first rotor of the inner rotor and the outer rotor so as to rotate therewith, and the battery is arranged to provide current to the first rotor of the inner rotor and the outer rotor, thereby causing the inner rotor and the outer rotor to rotate in opposite directions.

2. The counter-rotating fan drive assembly according to claim 1, wherein: The contra-rotating electric motor includes a motor controller fixed relative to a battery for rotation therewith, the motor controller being arranged to receive current from the battery and control current supply to a first rotor of the inner and outer rotors.

3. The counter-rotating fan drive assembly according to claim 1, wherein: The counter-rotating electric motor includes a motor mount assembly, and the drive shaft is rotatably mounted to the motor mount assembly.

4. The counter-rotating fan drive assembly according to claim 3, wherein: A first end of the drive shaft is rotatably mounted to the motor mount assembly, and a first impeller is fixedly connected to an opposing second end of the drive shaft.

5. The counter-rotating fan drive assembly according to claim 4, wherein: The inner rotor is disposed between the first end and the second end of the drive shaft.

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

7. The counter-rotating fan drive assembly according to any one of claims 1 to 5, wherein: The outer rotor includes a rotor housing rotatably mounted to the drive shaft, and the second impeller is fixedly connected to the rotor housing.

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

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

10. The counter-rotating fan drive assembly according to any one of claims 1 to 5, wherein: The inner rotor includes permanent magnets and the outer rotor includes electromagnets.

11. The counter-rotating fan drive assembly according to any one of claims 1 to 5, wherein: The inner rotor includes electromagnets and the outer rotor includes permanent magnets.

12. A counter-rotating fan drive assembly comprising: The first set of leaves; The second set of leaves; and a contra-rotating electric motor comprising a drive shaft, an inner rotor and an outer rotor, wherein the inner rotor is fixedly connected to the drive shaft and the outer rotor is arranged to rotate relative to the drive shaft; wherein the first set of blades is fixedly connected to the drive shaft for rotation therewith, and the second set of blades is fixedly connected to the outer rotor for rotation therewith; and The counter-rotating electric motor includes a battery fixed relative to a first rotor of the inner rotor and the outer rotor so as to rotate therewith, and the battery is arranged to provide current to the first rotor of the inner rotor and the outer rotor, thereby causing the inner rotor and the outer rotor to rotate in opposite directions.

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