GB2422495A - Electric motor assembly with a heat sink - Google Patents

Electric motor assembly with a heat sink Download PDF

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Publication number
GB2422495A
GB2422495A GB0501457A GB0501457A GB2422495A GB 2422495 A GB2422495 A GB 2422495A GB 0501457 A GB0501457 A GB 0501457A GB 0501457 A GB0501457 A GB 0501457A GB 2422495 A GB2422495 A GB 2422495A
Authority
GB
United Kingdom
Prior art keywords
stator
electric motor
rotor
heat sink
motor assembly
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0501457A
Other versions
GB0501457D0 (en
Inventor
Michael John Werson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Automotive Motion Technology Ltd
Original Assignee
Automotive Motion Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Automotive Motion Technology Ltd filed Critical Automotive Motion Technology Ltd
Priority to GB0501457A priority Critical patent/GB2422495A/en
Publication of GB0501457D0 publication Critical patent/GB0501457D0/en
Publication of GB2422495A publication Critical patent/GB2422495A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
    • H02K5/173—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using bearings with rolling contact, e.g. ball bearings
    • H02K5/1737—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using bearings with rolling contact, e.g. ball bearings radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K9/00—Arrangements for cooling or ventilating
    • H02K9/22—Arrangements for cooling or ventilating by solid heat conducting material embedded in, or arranged in contact with, the stator or rotor, e.g. heat bridges
    • H02K9/227—Heat sinks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K9/00—Arrangements for cooling or ventilating
    • H02K9/02—Arrangements for cooling or ventilating by ambient air flowing through the machine
    • H02K9/04—Arrangements for cooling or ventilating by ambient air flowing through the machine having means for generating a flow of cooling medium
    • H02K9/06—Arrangements for cooling or ventilating by ambient air flowing through the machine having means for generating a flow of cooling medium with fans or impellers driven by the machine shaft
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K9/00—Arrangements for cooling or ventilating
    • H02K9/22—Arrangements for cooling or ventilating by solid heat conducting material embedded in, or arranged in contact with, the stator or rotor, e.g. heat bridges
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/14—Structural association with mechanical loads, e.g. with hand-held machine tools or fans

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Motor Or Generator Cooling System (AREA)

Abstract

An electric motor assembly (10) including a generally annular stator (12) which encloses a generally cylindrical space, a rotor (14) which is supported for rotation on a bearing assembly (16), an electrical or electronic control apparatus (18), and a heat sink (20) on which at least some electrical or electronic components of the control apparatus (18) are mounted, a rotatable assembly (32) which is connected to the rotor (14) so that operation of the motor causes rotation of the rotatable assembly (32), wherein the rotatable assembly (32) is adapted on rotation to cause flow of air along an air flow path which extends through the generally cylindrical space enclosed by the stator (12), and at least a portion of the heat sink (20) extends into the generally cylindrical space enclosed by the stator (12) and supports the rotor bearing assembly (16).

Description

Title: Electric Motor Assembly
Description of Invention
The present invention relates to an electric motor assembly, particularly, but not exclusively to an electric motor driven fan for use in cooling a radiator in a motor vehicle.
It is known to use an electric motor such as a brushless motor to drive a fan for cooling a radiator in a motor vehicle. Operation of an electric motor such as a brushless electric motor generates heat - not only do the windings of * a the motor generate heat, but also the electrical and/or electronic components used to control the motor. Thus, where such a motor is used to drive a cooling Is,. 14 fan for use in cooling a radiator in a motor vehicle, it maybe necessary to provide means for cooling the motor itself in addition to the means for cooling S the radiator.
It is known, for example from EP1050682A1, to modif' the fan to include a structure which causes flow of cooling air through a cooling air path extending through the motor, thus providing cooling for the motor itself. More specifically, the fan includes a hub, a plurality of radially outwardly extending main fan blades which are adapted, on rotation of the fan, to cause flow of cooling air over the radiator, and a plurality of radially inwardly extending auxiliary fan blades which are adapted, on rotation of the fan, to cause flow of air through the motor.
In the example disclosed in EP1050682A1, the motor has a stator including a stator body comprising a tubular portion around which conventional laminations and windings are arranged, and a radially widened portion which extends from one end of the tubular portion. The electrical/electronic components of the ECU are mounted on the radially widened portion of the stator body on the opposite side to the tubular portion of the stator body. The radially widened portion is provided with cooling fins which extend from the radially widened portion into the flow path of the cooling air driven through the motor. The flow path of the cooling air extends from around the radially widened portion of the stator body, through apertures provided in the stator laminations, and out of the motor. Thus some cooling of the ECU components and the stator laminations is provided.
According to a first aspect of the present invention we provide an electric motor assembly including a generally annular stator which encloses a generally cylindrical space, a rotor which is supported for rotation on a bearing assembly, an electrical or electronic control apparatus, and a heat sink on which at least some electrical or electronic components of the control apparatus are mounted, a rotatable assembly which is connected to the rotor so that operation * of the motor causes rotation of the rotatable assembly, wherein the rotatable *1 assembly is adapted on rotation to cause flow of air along an air flow path....
which extends through the generally cylindrical space enclosed by the stator, "* and at least a portion of the heat sink extends into the generally cylindrical space enclosed by the stator and supports the rotor bearing assembly.
By virtue of' the providing the air flow path through the cylindrical space enclosed by the stator, the air flow path has an increased crosssectional area and is therefore less restricted than the air flow path in the prior art design. As a consequence, resistance to air flow through the motor is reduced, and the flow rate increased. Moreover, the increase in cross-sectional area of the flow path maybe exploited to maximise the surface area of the heat sink in contact with the cooling air flow. Thus, more efficient cooling of both the stator and the heat sink, and hence the control unit, can be achieved.
The heat sink preferably includes a generally central support rod which extends along an axis of rotation of the rotor about which the rotor bearing assembly is mounted. Rotation of the bearing assembly within the heat sink during operation of the motor may further enhance movement of cooling air through the heat sink.
Preferably the heat sink includes a first part, most of which is located in the generally cylindrical space enclosed by the stator, and a second part which is not enclosed by the stator, the second part extending radially outwardly of the first part relative to an axis of rotation of the rotor.
In this case, preferably the electrical or electronic components of the control unit are mounted on the second part of the heat sink.
The stator includes a plurality of laminations about which are wound stator windings, the stator windings extending from the laminations at axially * :* opposite ends thereof. In this case, preferably the air flow path passes over the stator windings at one or both ends of the stator. Thus, cooling of the stator windings is further enhanced.
I.....
The rotatable assembly may include a hub which is connected to the rotor. In this case, the rotatable assembly may include a plurality of fan blades *. S...
which extend radially outwardly of the hub. Alternatively or additionally the.. : rotatable assembly may include a plurality of formations which extend radially inwardly of the hub and which drive flow of air along the air flow path during operation of the motor.
Preferably the portion of the heat sink which is located in the generally cylindrical space enclosed by the stator is provided with a plurality of cooling fins. By virtue of the provision of such fins, the surface area of the heat sink which is in contact with cooling air is increased, and cooling of the control apparatus is improved.
At least a proportion of the cooling fins may extend radially with respect to an axis of rotation of the rotor. In this case, some of the cooling fins may extend from the radially extending cooling fins at an angle thereto when viewed in transverse cross-section.
According to a second aspect of the invention we provide a method of cooling an electric motor assembly including a generally annular stator which encloses a generally cylindrical space, a rotor which is supported for rotation on a bearing assembly, an electrical or electronic control apparatus, and a heat sink on which at least some electrical or electronic components of the control apparatus are mounted, a rotatable assembly which is connected to the rotor so that operation of the motor causes rotation of the rotatable assembly, wherein the method includes rotating the rotatable assembly to cause flow of air along an air flow path which extends through the generally cylindrical space enclosed by the stator, and around at least a portion of the heat sink which extends into * the generally cylindrical space enclosed by the stator. . The invention will now be described with reference to the accompanying drawings of which, S.....
FIGURE 1 is an illustration of an exploded cross-section of a motor assembly according to the first aspect of the invention, and **. S...
FIGURE 2 is an illustration of a cross-section of the assembled motor: assembly of Figure 1.
Referring now to the figures, there is shown an electric motor assembly 10, which in this example includes a brushless motor. The motor assembly 10 includes a generally annular stator 12 which encloses a generally cylindrical space, a rotor 14 which is supported for rotation on a bearing assembly 16, an electrical or electronic control apparatus 18, and a heat sink 20 on which at least some electrical or electronic components of the control apparatus 18 are mounted.
The stator 12 comprises a plurality of laminations 22 and windings 24 which are wound around the laminations 22 in manner which is conventional in the art of electric motors, in particular of the brushless type. The windings 24 extend from the laminations 22 at opposite ends 1 2a, 1 2b of the stator.
The rotor 14 includes an annular top cap I 4a, and a side wall I 4b which extends from the outermost edge of the top cap 1 4a at right-angles thereto to enclose a generally cylindrical space in which the stator 12 is located. In use, the rotor 14 rotates about an axis of rotation A which extends generally centrally of and perpendicular to the top cap 14a. A plurality of magnets 26 are mounted at intervals around the interior surface of the side wall I 4b. The magnets 26 are slightly spaced from the outer surface of the stator 12 to allow free rotation of the rotor 14 around the stator 12. A plurality of apertures are provided at the intersection of the top cap 14a and the side wall 14b, spaced at generally regular intervals around the rotor 14. S. :* The bearing assembly 16 comprises a generally tubular part 16a which., extends from the innermost edge of the rotor top cap 14 generally perpendicular to the top cap 14a and from the same side of the top cap 14a as the side wall S..
...DTD: 14b. Two ball bearing assemblies 27a, 27b are mounted inside the tubular part S...
16a, one adjacent the top cap 14a and the other adjacent a free end of the.*.. S...
tubular part 16a.
The heat sink 20 is preferably made from aluminium or an aluminium alloy, and includes a cooling part 20a, most of which is located in the generally cylindrical space enclosed by the stator 12, and a support part 20b which is not enclosed by the stator 12, the support part 20b extending radially outwardly of the cooling part 20a relative to the axis of rotation A of the rotor 14.
The heat sink 20 is made up of a plurality of cooling fins 28. In this example, the heat sink 20 includes a generally central support tube 28a outwardly of which extend eight primary fins 28b which extend along the entire length (in the direction of the axis A) of the heat sink 20 and radially relative to the axis of rotation A. Each primary fin 28b is provided with eight secondary fins 28b, four along each side of the primary fin 28b. The secondary fins 28c also extend along the entire length of the heat sink 20 but are inclined at an angle to the primary fin 28b from which they extend. Thus, when viewed in transverse crosssection, the cooling part 20a resembles a snow-flake. The lengths of the secondary fins 28c perpendicular to the axis of rotation A are such that their ends form a generally circular array, which has a greater diameter in the support part lOb than in the cooling part 20a The outer diameter of the support part 20b of the heat sink 20 is approximately equal to the outer diameter of the stator 12.
There is a small change in diameter of the cooling part 20a of the heat sink 20 so as to provide a small step around the circumference of the cooling part 20a upon which the stator laminations 22 are supported. By mounting the stator 12 in contact with the heat sink 20, heat generated in the stator 12 may be: *. :* absorbed by the heat sink 20. .:: The cooling part 20a of the heat sink 20 also includes a generally central support rod 30 which is located inside the support tube 28a and extends along *..S.S the axis of rotation A of the rotor 14. The bearing assembly 16 is mounted on S...
the support rod 30, the two ball bearing assemblies 27a, 27b engaging with the.... *S.S
support rod 30 to ensure that the rotor 14 may rotate about the axis of rotation.. : A with minimal frictional losses.
The control apparatus 18, which is electrically connected to the stator windings 24 to control operation of the motor as is conventional in the art, is mounted on the support part 20b of the heat sink 20 in a recess provided in an opposite side of the support part 20b to the cooling part 20a. Thus, heat generated by the electrical and/or electronic components of the control apparatus may be readily absorbed by the heat sink 20.
A rotatable assembly 32 is connected to the rotor 14 so that operation of the motor causes rotation of the rotatable assembly 32. The rotatable assembly in this example includes a hub 32a which is connected to the rotor 14, a plurality of external fan blades 32b which extend radially outwardly of the hub 32a, and a plurality of internal fan blades 32c which extend radially inwardly of the hub 32a. The external fan blades 32b are of conventional design, and may be used, for example, to blow cooling air over a radiator in an automotive vehicle. The internal fan blades 32c are configured to cause flow of air along an air flow path through the motor to assist in cooling the motor. The air flow path will be described in more detail below.
The hub 32a of the rotatable assembly is connected to the top cap 14a of the rotor 14 by means of a central boss 32d which extends into the tubular part 1 6a of the rotor bearing assembly 16 and engages with the end of the support rod 30 of the heat sink 20.
On operation of the motor, rotation of the rotor 14 causes the rotatable assembly 32 to rotate. As result the external fan blades 32b blow air wherever: ** desired, in this example, over the radiator of an automotive vehicle, whilst the. : : internal fan blades 32c draw a separate flow of air along an air flow path which extends through the portion of the cooling fins 28 which form the support part * 20b of the heat sink 20, over the portion of the windings 24 which extend from the laminations 22 at the first end 1 2a of the stator 12, through the space... 0*Ss
enclosed by the stator 12 and around the fins 28 which form the cooling part ** 20a of the heat sink 20, over the portion of the windings 24 which extend from the laminations 22 at the second end I 2b of the stator 12, through the apertures provided in the rotor 14, past the internal fan blades 32c and out of the assembly 10. This flow path is illustrated by arrows in Figure 2. Thus, the air flow may assist in cooling the stator windings 24 and laminations 22, the heat sink 20, and hence the control apparatus 18.
By virtue of the providing the air flow path through the cylindrical space enclosed by the stator 12, the air flow path has an increased crosssectional area and is therefore less restricted than the air flow path in prior art designs. As a consequence, resistance to air flow through the motor is reduced, and the flow rate increased. Moreover, the increase in cross-sectional area of the flow path maybe exploited to maximise the surface area of the heat sink 20 in contact with the cooling air flow. It will be appreciated that the provision of the fins 28b, 28c also increases the surface area of the heat sink 20 in contact with the cooling air, and therefore further enhances cooling of the heat sink 20. Finally, rotation of the bearing assembly 16 within the heat sink 20 during operation of the motor may further enhance movement of cooling air through the heat sink 20.
When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.
The features disclosed in the foregoing description, or the following: ** claims, or the accompanying drawings, expressed in their specific forms or in: : terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any, S.....
combination of such features, be utilised for realising the invention in diverse S...
forms thereof. S...
S S S S. *

Claims (16)

1. An electric motor assembly including a generally annular stator which encloses a generally cylindrical space, a rotor which is supported for rotation on a bearing assembly, an electrical or electronic control apparatus, and a heat sink on which at least some electrical or electronic components of the control apparatus are mounted, a rotatable assembly which is connected to the rotor so that operation of the motor causes rotation of the rotatable assembly, wherein the rotatable assembly is adapted on rotation to cause flow of air along an air flow path which extends through the generally cylindrical space enclosed by the * :* stator, and at least a portion of the heat sink extends into the generally.* : * cylindrical space enclosed by the stator and supports the rotor bearing assembly. ***.S
2. An electric motor assembly according to claim 1 wherein the heat sink..
includes a generally central support rod which extends along an axis of rotation * : of the rotor about which the rotor bearing assembly is mounted.
3. An electric motor assembly according to claim 1 or 2 whererin the heat sink includes a first part, most of which is located in the generally cylindrical space enclosed by the stator, and a second part which is not enclosed by the stator, the second part extending radially outwardly of the first part relative to an axis of rotation of the rotor.
4. An electric motor assembly according to claim 3 wherein the electrical or electronic components of the control unit are mounted on the second part of the heat sink.
5. An electric motor assembly according to any preceding claim wherein the stator includes a plurality of laminations about which are wound stator windings, the stator windings extending from the laminations at axially opposite ends thereof
6. An electric motor assembly according to claim 5 wherein the air flow path passes over the stator windings at one or both ends of the stator.
7. An electric motor assembly according to any preceding claim wherein the rotatable assembly includes a hub which is connected to the rotor. * . ** * S
S
8. An electric motor assembly according to claim 7 wherein the rotatable assembly includes a plurality of fan blades which extend radially outwardly of S.....
the hub. S...
9. An electric motor assembly according to claim 7 or 8 wherein the.. : rotatable assembly includes a plurality of formations which extend radially inwardly of the hub and which drive flow of air along the air flow path during operation of the motor.
10. An electric motor assembly according to any preceding claim wherein at least the portion of the heat sink which is located in the generally cylindrical space enclosed by the stator is provided with a plurality of cooling fins.
11. An electric motor assembly according to claim 10 wherein at least a proportion of the cooling fins extend radially with respect to an axis of rotation of the rotor.
12. An electric motor assembly according to claim 11 wherein some of the cooling fins extend from the radially extending cooling fins at an angle thereto when viewed in transverse cross-section.
13. A method of cooling an electric motor assembly including a generally annular stator which encloses a generally cylindrical space, a rotor which is supported for rotation on a bearing assembly, an electrical or electronic control apparatus, and a heat sink on which at least some electrical or electronic components of the control apparatus are mounted, a rotatable assembly which is connected to the rotor so that operation of the motor causes rotation of the: * rotatable assembly, wherein the method includes rotating the rotatable assembly to cause flow of air along an air flow path which extends through the generally cylindrical space enclosed by the stator, and around at least a portion of the heat S.
, sink which extends into the generally cylindrical space enclosed by the stator. S.. I..,..CLME:
14. An electric motor assembly substantially as hereinbefore described with.. : reference to and as shown in the accompanying drawings.
15. A method of cooling an electric motor assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
16. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.
GB0501457A 2005-01-25 2005-01-25 Electric motor assembly with a heat sink Withdrawn GB2422495A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0501457A GB2422495A (en) 2005-01-25 2005-01-25 Electric motor assembly with a heat sink

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0501457A GB2422495A (en) 2005-01-25 2005-01-25 Electric motor assembly with a heat sink

Publications (2)

Publication Number Publication Date
GB0501457D0 GB0501457D0 (en) 2005-03-02
GB2422495A true GB2422495A (en) 2006-07-26

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB0501457A Withdrawn GB2422495A (en) 2005-01-25 2005-01-25 Electric motor assembly with a heat sink

Country Status (1)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2262080A1 (en) * 2008-04-03 2010-12-15 Yu Tian A brushless dc motor and a radiator thereof
DE102013215808A1 (en) * 2013-08-09 2015-02-12 Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Würzburg Rotor hub assembly, electric fan

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60216737A (en) * 1984-04-12 1985-10-30 Mitsubishi Electric Corp Fly-wheel power source apparatus
US6830440B1 (en) * 1999-10-08 2004-12-14 Minebea Co. Ltd. External rotor brushless DC motor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60216737A (en) * 1984-04-12 1985-10-30 Mitsubishi Electric Corp Fly-wheel power source apparatus
US6830440B1 (en) * 1999-10-08 2004-12-14 Minebea Co. Ltd. External rotor brushless DC motor

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2262080A1 (en) * 2008-04-03 2010-12-15 Yu Tian A brushless dc motor and a radiator thereof
EP2262080A4 (en) * 2008-04-03 2012-11-28 Yu Tian A brushless dc motor and a radiator thereof
DE102013215808A1 (en) * 2013-08-09 2015-02-12 Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Würzburg Rotor hub assembly, electric fan
US10107301B2 (en) 2013-08-09 2018-10-23 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Wurzburg Rotor hub assembly, electric fan

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Publication number Publication date
GB0501457D0 (en) 2005-03-02

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