WO2019180410A1 - Radial flux electrical machines - Google Patents

Radial flux electrical machines Download PDF

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Publication number
WO2019180410A1
WO2019180410A1 PCT/GB2019/050749 GB2019050749W WO2019180410A1 WO 2019180410 A1 WO2019180410 A1 WO 2019180410A1 GB 2019050749 W GB2019050749 W GB 2019050749W WO 2019180410 A1 WO2019180410 A1 WO 2019180410A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrical machine
rotor
driveshaft
clutch assembly
stator
Prior art date
Application number
PCT/GB2019/050749
Other languages
French (fr)
Inventor
Lloyd Ash
Original Assignee
Ashwoods Electric Motors Limited
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 Ashwoods Electric Motors Limited filed Critical Ashwoods Electric Motors Limited
Publication of WO2019180410A1 publication Critical patent/WO2019180410A1/en

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Classifications

    • 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
    • H02K7/006—Structural association of a motor or generator with the drive train of a motor vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
    • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
    • B60K6/22—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by apparatus, components or means specially adapted for HEVs
    • B60K6/38—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by apparatus, components or means specially adapted for HEVs characterised by the driveline clutches
    • B60K6/383—One-way clutches or freewheel devices
    • 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
    • H02K7/10—Structural association with clutches, brakes, gears, pulleys or mechanical starters
    • H02K7/108—Structural association with clutches, brakes, gears, pulleys or mechanical starters with friction clutches
    • 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
    • H02K7/18—Structural association of electric generators with mechanical driving motors, e.g. with turbines
    • H02K7/1807—Rotary generators
    • H02K7/1815—Rotary generators structurally associated with reciprocating piston engines
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/14—Stator cores with salient poles
    • H02K1/146—Stator cores with salient poles consisting of a generally annular yoke with salient poles
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/27—Rotor cores with permanent magnets
    • H02K1/2706—Inner rotors
    • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
    • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
    • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
    • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
    • H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect
    • 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
    • H02K7/003—Couplings; Details of shafts
    • 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

Definitions

  • the present invention relates to radial flux electrical machines in which magnetic flux is induced in a radial direction between a stator and a rotor mounted for rotation within the stator.
  • Conventional radial flux electrical machines comprise a body that provides a stator housing having a plurality stator cores arranged around an inner surface of the stator housing. An inner volume is defined within the stator housing inside the stator cores. Electrically conductive coils are arranged around respective stator cores and operate to generate a magnetic flux in a radial direction within the stator.
  • a cylindrical rotor which may include a plurality of permanent magnets, is arranged inside the inner volume of the stator for rotation with respect to the stator.
  • An air gap is defined between the rotor and the stator. In use, the rotor interacts with the magnetic flux field generated by passing electrical current through the stator coils, thereby producing a force which causes the rotor to rotate with respect to the stator.
  • One previously-considered design of radial flux electrical machine is shown in UK Patent No. 2532963.
  • Such radial flux electrical machines have been combined with power sources, such as internal combustion engines, in order to provide hybrid power for vehicles.
  • a vehicle When using an internal combustion engine in combination with the electrical machine, a vehicle may be powered directly by the internal combustion engine, or in a hybrid mode in which the electrical machine works with the ICE.
  • the ICE may also be used to drive the electrical machine as a generator.
  • Embodiments of the present invention seek to address the problems of the existing designs.
  • a radial flux electrical machine comprising a housing that defines a longitudinal axis, a substantially cylindrical inner surface and an inner volume; a stator assembly having a plurality of electromagnetic elements, each of which includes a stator core of ferromagnetic material and a winding of electrically conductive material located around at least part of the stator core of the electromagnetic element concerned, the electromagnetic elements being arranged around the inner surface of the housing, and operable to induce a magnetic flux field in a radial direction in the inner volume of the housing; an input driveshaft which extends into the inner volume along the longitudinal axis, and which is rotatable with respect to the stator; a rotor located radially outwardly of the input driveshaft within the inner volume of the stator, and rotatable with respect to the stator; an output driveshaft for rotation with the rotor; and a one way clutch assembly located radially between the input driveshaft and the rotor, the one-way clutch assembly having a first
  • the clutch assembly is located radially between the input driveshaft and the rotor. In one example, the clutch assembly is located axially adjacent the rotor.
  • the clutch assembly is actuated between the first and second modes of operation by rotation of the input driveshaft.
  • the clutch assembly may be a freewheel clutch assembly, a trapped roller clutch assembly a sprag clutch assembly, or any other suitable clutch assembly.
  • relative rotation between the rotor and the input driveshaft in a first direction results in the first mode of operation
  • relative rotation between the rotor and the input driveshaft in a second direction results in the second mode of operation.
  • drivetrain comprising a radial flux electrical machine according to the first aspect of the present invention; a secondary power source having an output driveshaft which is attached for rotation with the input driveshaft of the electrical machine, wherein the drivetrain has a first mode of operation in which only the electrical machine supplies torque to the output driveshaft, a second mode of operation in which the electrical machine and the secondary power source supply torque to the output driveshaft.
  • One example drivetrain has a third mode of operation in which the secondary power source drives the electrical machine a generator.
  • the secondary power source may be an internal combustion engine.
  • Figure 1 is a first schematic perspective view of an electrical machine embodying the present invention
  • Figure 2 is a second schematic perspective view the electrical machine of Figure 1 ;
  • Figure 3 is a schematic perspective view of the electrical machine of Figures 1 and 2, with outer covers removed;
  • Figure 4 is a first schematic cross-sectional perspective view of the electrical machine of Figures 1 , 2 and 3;
  • Figure 5 is a second schematic cross-sectional perspective view of the electrical machine of Figures 1 to 4;
  • Figure 6 is a schematic cross-sectional view of the electrical machine of Figures 1 to 5;
  • Figure 7 is a schematic end view of a clutch assembly of the electrical machine of Figures 1 to 6;
  • Figure 8 is a schematic illustration of a drivetrain employing the electrical machine of Figures 1 to 6.
  • Figure 1 and 2 are respective perspective views of an electrical machine 1 embodying the present invention.
  • Figure 1 is seen from a first end of the electrical machine 1
  • Figure 2 is seen from a second end of the machine 1 , opposite to the first end.
  • the electrical machine 1 includes a cylindrical housing 10.
  • the outer profile of the housing need not be cylindrical but may be of any suitable shape dependent upon the application and use of the electrical machine 1.
  • a first open end of the housing 10 is substantially covered by a first cover 12, which is attached to a first end of the housing 10.
  • a second open end of the housing 10 is substantially covered by a second cover 14, which is attached to a second end of the housing 10.
  • the second cover 14 is provided with heatsink fins 16 for dissipation of heat generated within the electrical machine 1.
  • the heatsink fins are optional and are dependent upon the application and use of the electrical machine.
  • An input driveshaft 18 extends into the electrical machine 1 through the first cover 12, and an output driveshaft 20 extends out of the electrical machine 1 through the second cover 14.
  • Electrical connections 22 extend from the second cover 14 and are provided to connect the electrical elements of the electrical machine 1 to external power and control units, in well-known manner.
  • FIG 3 is a schematic perspective view of the electrical machine 1 , with the first and second covers 12 and 14 removed from the housing 10.
  • the housing 10 defines an inner volume in which a stator assembly 24 and rotor 26 are located.
  • the rotor 26 is rotatable within, and with respect to, the stator assembly 24.
  • the stator assembly 24 comprises a plurality of stator elements 28 arranged around an inner surface of the housing 10.
  • Each stator element 28 comprises a stator winding 30 which wound around a stator core 32 attached to the housing 10 and extending into the inner volume of the housing 10.
  • Each stator winding 30 is of electrically conductive material, such as copper wire or bar, which is wound in a coil structure that encircles the stator core 32 of the stator element 28 concerned.
  • Each stator winding 30 is connected electrically to power and control unit, in known manner.
  • the rotor 26 comprises a rotor body 34 mounted for rotation with respect to the stator assembly 24.
  • the rotor 26 also includes a plurality of permanent magnetic elements 36.
  • the rotor may also be provided by an inductive rotor.
  • alternating current electrical power is supplied to the stator windings 30 which induce an alternating magnetic field within the inner volume of the housing 10.
  • the magnetic elements 36 of the rotor 26 interact with the alternating magnetic field, in known manner, to generate a force on the magnetic elements. This induced force serves to rotate the rotor 26 with respect to the stator assembly 24.
  • the rotor 26 when operating as a generator, the rotor 26 is caused to rotate by an external system, for example an internal combustion engine, and this rotation induces magnetic fields in the stator cores 32. Such induced magnetic fields create respective flows of electrical current in the stator windings 30. The electrical current is the output from the electrical machine.
  • an external system for example an internal combustion engine
  • Figure 4, 5 and 6 illustrate respective cross-sectional schematic views of an electrical machine embodying the present invention.
  • the electrical machine 1 includes a housing 10, and first and second covers 12 and 14 which define an inner volume of the machine 1.
  • the housing 10 defines a longitudinal axis 1 1 of the electrical machine 1.
  • a stator assembly 24 is located within the inner volume and is arranged around an inner surface of the housing 10, radially outwardly of the longitudinal axis 1 1.
  • the stator assembly 24 comprises a plurality of electromagnetic stator elements, each of which includes a stator winding 30 of electrically conductive material extending at least partially around a stator core 32 of ferromagnetic material.
  • the electromagnetic stator elements are operable to induce a magnetic flux field in a radial direction in the inner volume of the housing 10.
  • An input driveshaft 18 extends along the longitudinal axis 11 , into the inner volume of the housing 10, and is rotatable with respect to the stator assembly 24.
  • a rotor 26, including magnetic elements 36, is located radially outwardly of the input driveshaft 18 within the inner volume of the housing 10, and rotatable with respect to the stator assembly 24.
  • a one-way clutch assembly 40 is located on the longitudinal axis radially between the input driveshaft 18 and the rotor 26.
  • the clutch assembly 40 is operable to engage the input driveshaft 18 with the rotor 26 when relative rotation between the two is in one direction, and to disengage the input driveshaft 18 and the rotor 26 when relative rotation of the two is in the other opposite direction.
  • the clutch assembly 40 therefore, has a first mode of operation in which the rotor is rotatable with respect to the input driveshaft, and a second mode of operation in which the rotor is engaged for rotation with the input driveshaft.
  • the clutch assembly 40 is connected with the rotor 26 by way of a rotor adaptor 42. Seals 44 are located between the clutch assembly 40 and the housing 10.
  • FIG. 7 illustrates an exemplary schematic structure of the clutch assembly 40.
  • the clutch assembly 40 is a concentric one-way clutch assembly and includes an inner race 46.
  • An outer race 48 is concentric with the inner race 46 and is radially outward of the inner race 46.
  • the inner and outer race 46 and 48 are rotatable with respect to one another.
  • a clutch mechanism 50 is located radially between the inner and outer races 46 and 48.
  • the clutch mechanism 50 serves to allow the outer race 48 to rotate freely about the inner race 46 when the relative rotation between the two races 46 and 48 is in a first direction.
  • Such rotation of the outer race 48 occurs when the inner race is stationary, rotating in the opposite direction to the outer race 48, or is rotating in the first direction at a slower speed than the outer race 48.
  • the clutch mechanism 50 When the inner race 46 rotates in the first direction at a speed equal to that of the outer race 48 in the first direction, the clutch mechanism 50 operates to engage the inner race 46 with the outer race 48, so that the inner and outer races 46 and 48 rotate together. In this configuration, torque is transferred from the inner race 46 to the outer race 48.
  • clutch assembly 40 examples include freewheel clutch assemblies, trapped roller clutch assemblies, and sprag clutch assemblies.
  • input driveshaft 18 is attached to the inner race 46 of the clutch assembly 40 for rotation therewith.
  • the outer race 48 of the clutch assembly 40 is attached to the rotor 26, in this example using the rotor adaptor 42. It will be readily appreciated that the rotor adaptor is optional and may be integral with the rotor 26 or clutch assembly 40.
  • the outer race 48 of the clutch assembly is also attached to the output driveshaft 20. Accordingly, the outer race 48, the rotor 26 and the output shaft 20 are connected together for rotation together about the longitudinal axis, relative to the housing 10 and stator assembly 24.
  • a secondary power source such as an internal combustion engine (ICE) is arranged to connect its output driveshaft to the input driveshaft 18 of the electrical machine 1.
  • ICE internal combustion engine
  • the drivetrain arrangement 60 includes an electrical machine 62, having an input driveshaft 64 and an output driveshaft 66.
  • the output driveshaft 66 provides the output driveshaft of the drivetrain arrangement 60.
  • a control and electrical power unit 68 is provided for controlling operation of the electrical machine 62 and is operable to supply power to the electrical machine 62 when operating as a motor, and to receive electrical power when acting as a generator.
  • a secondary power source 70 has an output driveshaft connected to the input driveshaft 64 to provide rotational drive to the input driveshaft 64.
  • clutch and rotor may be different to that shown in the Figures.
  • the clutch may be arranged to be axially adjacent the rotor, instead of radially adjacent the rotor as shown in the Figures.
  • Such a drivetrain arrangement has several modes of operation (referring to Figures 4 to 8):
  • the input driveshaft 18, 64 is stationary (or rotating more slowly than the rotor 26), such that the rotor 26 is able to rotate with respect to the input driveshaft 18, 64.
  • the clutch assembly 40 is disengaged, and the output driveshaft 20, 66 receives torque only from the electrical machine 1 , 62.
  • the first mode of operation is an electric-only drive mode.
  • the input driveshaft 18, 64 is driven by the secondary power source 70 and rotates in the first direction, at the same speed as the rotor 26.
  • the output driveshaft 20, 66 receives torque from both the electrical machine 1 , 62 and from the secondary power source 70.
  • the second mode of operation is a hybrid-boost drive mode.
  • the input driveshaft 18, 64 is driven by the secondary power source 70 and rotates in the first direction, such that the clutch assembly 40 engages.
  • the input driveshaft 18, 64 then drives the rotor 26 of the electrical machine 1 , which causes electrical power to be induced in the stator assembly 24 and supplied to the control and electrical power unit 70.
  • the output driveshaft 20, 66 receives torque only from the secondary power source.
  • This third mode of operation is a generator/ICE drive mode.
  • Embodiments of the present invention are able to provide a compact electrical machine that, when combined with an appropriate secondary power source, provide electric-only drive, hybrid-boost drive and generator modes of operation. Such embodiments enable drivetrains that are primarily electrically powered drivetrains, but with the ability for boost and generator modes.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

A radial flux electrical machine (1) includes a one-way clutch assembly (40) which operates between an input driveshaft (18) and an output driveshaft (20).

Description

RADIAL FLUX ELECTRICAL MACHINES
The present invention relates to radial flux electrical machines in which magnetic flux is induced in a radial direction between a stator and a rotor mounted for rotation within the stator.
BACKGROUND TO THE INVENTION
Conventional radial flux electrical machines comprise a body that provides a stator housing having a plurality stator cores arranged around an inner surface of the stator housing. An inner volume is defined within the stator housing inside the stator cores. Electrically conductive coils are arranged around respective stator cores and operate to generate a magnetic flux in a radial direction within the stator. A cylindrical rotor, which may include a plurality of permanent magnets, is arranged inside the inner volume of the stator for rotation with respect to the stator. An air gap is defined between the rotor and the stator. In use, the rotor interacts with the magnetic flux field generated by passing electrical current through the stator coils, thereby producing a force which causes the rotor to rotate with respect to the stator. One previously-considered design of radial flux electrical machine is shown in UK Patent No. 2532963.
Such radial flux electrical machines have been combined with power sources, such as internal combustion engines, in order to provide hybrid power for vehicles. When using an internal combustion engine in combination with the electrical machine, a vehicle may be powered directly by the internal combustion engine, or in a hybrid mode in which the electrical machine works with the ICE. The ICE may also be used to drive the electrical machine as a generator.
Embodiments of the present invention seek to address the problems of the existing designs.
SUMMARY OF THE INVENTION
Aspects of the present invention are set out in the attached claims.
According to an aspect of the present invention, there is provided a radial flux electrical machine comprising a housing that defines a longitudinal axis, a substantially cylindrical inner surface and an inner volume; a stator assembly having a plurality of electromagnetic elements, each of which includes a stator core of ferromagnetic material and a winding of electrically conductive material located around at least part of the stator core of the electromagnetic element concerned, the electromagnetic elements being arranged around the inner surface of the housing, and operable to induce a magnetic flux field in a radial direction in the inner volume of the housing; an input driveshaft which extends into the inner volume along the longitudinal axis, and which is rotatable with respect to the stator; a rotor located radially outwardly of the input driveshaft within the inner volume of the stator, and rotatable with respect to the stator; an output driveshaft for rotation with the rotor; and a one way clutch assembly located radially between the input driveshaft and the rotor, the one-way clutch assembly having a first mode of operation in which the rotor is rotatable with respect to the input driveshaft, and a second mode of operation in which the rotor is engaged for rotation with the input driveshaft.
In one example, the clutch assembly is located radially between the input driveshaft and the rotor. In one example, the clutch assembly is located axially adjacent the rotor.
In one example, the clutch assembly is actuated between the first and second modes of operation by rotation of the input driveshaft.
The clutch assembly may be a freewheel clutch assembly, a trapped roller clutch assembly a sprag clutch assembly, or any other suitable clutch assembly. In one example, relative rotation between the rotor and the input driveshaft in a first direction results in the first mode of operation, and wherein relative rotation between the rotor and the input driveshaft in a second direction results in the second mode of operation.
According to another aspect of the present invention drivetrain comprising a radial flux electrical machine according to the first aspect of the present invention; a secondary power source having an output driveshaft which is attached for rotation with the input driveshaft of the electrical machine, wherein the drivetrain has a first mode of operation in which only the electrical machine supplies torque to the output driveshaft, a second mode of operation in which the electrical machine and the secondary power source supply torque to the output driveshaft. One example drivetrain has a third mode of operation in which the secondary power source drives the electrical machine a generator.
The secondary power source may be an internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a first schematic perspective view of an electrical machine embodying the present invention;
Figure 2 is a second schematic perspective view the electrical machine of Figure 1 ; Figure 3 is a schematic perspective view of the electrical machine of Figures 1 and 2, with outer covers removed;
Figure 4 is a first schematic cross-sectional perspective view of the electrical machine of Figures 1 , 2 and 3;
Figure 5 is a second schematic cross-sectional perspective view of the electrical machine of Figures 1 to 4;
Figure 6 is a schematic cross-sectional view of the electrical machine of Figures 1 to 5;
Figure 7 is a schematic end view of a clutch assembly of the electrical machine of Figures 1 to 6; and
Figure 8 is a schematic illustration of a drivetrain employing the electrical machine of Figures 1 to 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 and 2 are respective perspective views of an electrical machine 1 embodying the present invention. Figure 1 is seen from a first end of the electrical machine 1 , and Figure 2 is seen from a second end of the machine 1 , opposite to the first end. The electrical machine 1 includes a cylindrical housing 10. The outer profile of the housing need not be cylindrical but may be of any suitable shape dependent upon the application and use of the electrical machine 1.
A first open end of the housing 10 is substantially covered by a first cover 12, which is attached to a first end of the housing 10. A second open end of the housing 10 is substantially covered by a second cover 14, which is attached to a second end of the housing 10. The second cover 14 is provided with heatsink fins 16 for dissipation of heat generated within the electrical machine 1. The heatsink fins are optional and are dependent upon the application and use of the electrical machine. An input driveshaft 18 extends into the electrical machine 1 through the first cover 12, and an output driveshaft 20 extends out of the electrical machine 1 through the second cover 14.
Electrical connections 22 extend from the second cover 14 and are provided to connect the electrical elements of the electrical machine 1 to external power and control units, in well- known manner.
Figure 3 is a schematic perspective view of the electrical machine 1 , with the first and second covers 12 and 14 removed from the housing 10. As can be seen in Figure 3, the housing 10 defines an inner volume in which a stator assembly 24 and rotor 26 are located. The rotor 26 is rotatable within, and with respect to, the stator assembly 24. The stator assembly 24 comprises a plurality of stator elements 28 arranged around an inner surface of the housing 10. Each stator element 28 comprises a stator winding 30 which wound around a stator core 32 attached to the housing 10 and extending into the inner volume of the housing 10. Each stator winding 30 is of electrically conductive material, such as copper wire or bar, which is wound in a coil structure that encircles the stator core 32 of the stator element 28 concerned. Each stator winding 30 is connected electrically to power and control unit, in known manner.
The rotor 26 comprises a rotor body 34 mounted for rotation with respect to the stator assembly 24. The rotor 26 also includes a plurality of permanent magnetic elements 36.
The rotor may also be provided by an inductive rotor.
As is well known, when operating as a motor, alternating current electrical power is supplied to the stator windings 30 which induce an alternating magnetic field within the inner volume of the housing 10. The magnetic elements 36 of the rotor 26 interact with the alternating magnetic field, in known manner, to generate a force on the magnetic elements. This induced force serves to rotate the rotor 26 with respect to the stator assembly 24.
As is also well known, when operating as a generator, the rotor 26 is caused to rotate by an external system, for example an internal combustion engine, and this rotation induces magnetic fields in the stator cores 32. Such induced magnetic fields create respective flows of electrical current in the stator windings 30. The electrical current is the output from the electrical machine.
Figure 4, 5 and 6 illustrate respective cross-sectional schematic views of an electrical machine embodying the present invention. As described above, the electrical machine 1 includes a housing 10, and first and second covers 12 and 14 which define an inner volume of the machine 1. The housing 10 defines a longitudinal axis 1 1 of the electrical machine 1.
A stator assembly 24 is located within the inner volume and is arranged around an inner surface of the housing 10, radially outwardly of the longitudinal axis 1 1. The stator assembly 24 comprises a plurality of electromagnetic stator elements, each of which includes a stator winding 30 of electrically conductive material extending at least partially around a stator core 32 of ferromagnetic material. The electromagnetic stator elements are operable to induce a magnetic flux field in a radial direction in the inner volume of the housing 10.
An input driveshaft 18 extends along the longitudinal axis 11 , into the inner volume of the housing 10, and is rotatable with respect to the stator assembly 24.
A rotor 26, including magnetic elements 36, is located radially outwardly of the input driveshaft 18 within the inner volume of the housing 10, and rotatable with respect to the stator assembly 24.
A one-way clutch assembly 40 is located on the longitudinal axis radially between the input driveshaft 18 and the rotor 26. The clutch assembly 40 is operable to engage the input driveshaft 18 with the rotor 26 when relative rotation between the two is in one direction, and to disengage the input driveshaft 18 and the rotor 26 when relative rotation of the two is in the other opposite direction. The clutch assembly 40, therefore, has a first mode of operation in which the rotor is rotatable with respect to the input driveshaft, and a second mode of operation in which the rotor is engaged for rotation with the input driveshaft. In the example embodiment illustrated, the clutch assembly 40 is connected with the rotor 26 by way of a rotor adaptor 42. Seals 44 are located between the clutch assembly 40 and the housing 10.
Figure 7 illustrates an exemplary schematic structure of the clutch assembly 40. The clutch assembly 40 is a concentric one-way clutch assembly and includes an inner race 46. An outer race 48 is concentric with the inner race 46 and is radially outward of the inner race 46. The inner and outer race 46 and 48 are rotatable with respect to one another. A clutch mechanism 50 is located radially between the inner and outer races 46 and 48. In such a one-way clutch assembly, the clutch mechanism 50 serves to allow the outer race 48 to rotate freely about the inner race 46 when the relative rotation between the two races 46 and 48 is in a first direction. Such rotation of the outer race 48 occurs when the inner race is stationary, rotating in the opposite direction to the outer race 48, or is rotating in the first direction at a slower speed than the outer race 48. When the inner race 46 rotates in the first direction at a speed equal to that of the outer race 48 in the first direction, the clutch mechanism 50 operates to engage the inner race 46 with the outer race 48, so that the inner and outer races 46 and 48 rotate together. In this configuration, torque is transferred from the inner race 46 to the outer race 48.
Examples of appropriate mechanisms for the clutch assembly 40 include freewheel clutch assemblies, trapped roller clutch assemblies, and sprag clutch assemblies.
Referring to Figure 4 to 7, input driveshaft 18 is attached to the inner race 46 of the clutch assembly 40 for rotation therewith. The outer race 48 of the clutch assembly 40 is attached to the rotor 26, in this example using the rotor adaptor 42. It will be readily appreciated that the rotor adaptor is optional and may be integral with the rotor 26 or clutch assembly 40.
The outer race 48 of the clutch assembly is also attached to the output driveshaft 20. Accordingly, the outer race 48, the rotor 26 and the output shaft 20 are connected together for rotation together about the longitudinal axis, relative to the housing 10 and stator assembly 24.
In an application, a secondary power source, such as an internal combustion engine (ICE), is arranged to connect its output driveshaft to the input driveshaft 18 of the electrical machine 1. Such an arrangement is usefully employed as a drivetrain for a vehicle. Such an arrangement is illustrated in Figure 8. The drivetrain arrangement 60 includes an electrical machine 62, having an input driveshaft 64 and an output driveshaft 66. The output driveshaft 66 provides the output driveshaft of the drivetrain arrangement 60. A control and electrical power unit 68 is provided for controlling operation of the electrical machine 62 and is operable to supply power to the electrical machine 62 when operating as a motor, and to receive electrical power when acting as a generator. A secondary power source 70 has an output driveshaft connected to the input driveshaft 64 to provide rotational drive to the input driveshaft 64.
It will be readily appreciated that the specific arrangement of clutch and rotor may be different to that shown in the Figures. For example, the clutch may be arranged to be axially adjacent the rotor, instead of radially adjacent the rotor as shown in the Figures.
Such a drivetrain arrangement has several modes of operation (referring to Figures 4 to 8):
A first mode in which electrical power is supplied to the stator assembly of the electrical machine 1 , 62 so that it operates as a motor, with the rotor 26 rotating in the first direction. The input driveshaft 18, 64 is stationary (or rotating more slowly than the rotor 26), such that the rotor 26 is able to rotate with respect to the input driveshaft 18, 64. In this first mode of operation, the clutch assembly 40 is disengaged, and the output driveshaft 20, 66 receives torque only from the electrical machine 1 , 62. The first mode of operation is an electric-only drive mode. A second mode in which electrical power is supplied to the stator assembly 24 of the electrical machine 1 , 60 so that it operates as a motor, with the rotor 26 rotating in the first direction. The input driveshaft 18, 64 is driven by the secondary power source 70 and rotates in the first direction, at the same speed as the rotor 26. In this second mode of operation, the output driveshaft 20, 66 receives torque from both the electrical machine 1 , 62 and from the secondary power source 70. The second mode of operation is a hybrid-boost drive mode.
A third mode in which electrical power is not supplied to the stator assembly 24 of the electrical machine 1 , 60 so that it operates as a generator. The input driveshaft 18, 64 is driven by the secondary power source 70 and rotates in the first direction, such that the clutch assembly 40 engages. The input driveshaft 18, 64, then drives the rotor 26 of the electrical machine 1 , which causes electrical power to be induced in the stator assembly 24 and supplied to the control and electrical power unit 70. The output driveshaft 20, 66 receives torque only from the secondary power source. This third mode of operation is a generator/ICE drive mode.
Embodiments of the present invention are able to provide a compact electrical machine that, when combined with an appropriate secondary power source, provide electric-only drive, hybrid-boost drive and generator modes of operation. Such embodiments enable drivetrains that are primarily electrically powered drivetrains, but with the ability for boost and generator modes.

Claims

CLAIMS:
1. A radial flux electrical machine comprising:
a housing that defines a longitudinal axis, a substantially cylindrical inner surface and an inner volume;
a stator assembly having a plurality of electromagnetic elements, each of which includes a stator core of ferromagnetic material and a winding of electrically conductive material located around at least part of the stator core of the electromagnetic element concerned, the electromagnetic elements being arranged around the inner surface of the housing, and operable to induce a magnetic flux field in a radial direction in the inner volume of the housing;
an input driveshaft which extends into the inner volume along the longitudinal axis, and which is rotatable with respect to the stator;
a rotor located radially outwardly of the input driveshaft within the inner volume of the stator, and rotatable with respect to the stator;
an output driveshaft for rotation with the rotor; and
a one-way clutch assembly located to connect the input driveshaft and the rotor, the one-way clutch assembly having a first mode of operation in which the rotor is rotatable with respect to the input driveshaft, and a second mode of operation in which the rotor is engaged for rotation with the input driveshaft.
2. A radial flux electrical machine as claimed in claim 1 , wherein the clutch assembly is located radially between the input driveshaft and the rotor.
3. A radial flux electrical machine as claim in claim 1 , wherein the clutch assembly is located axially adjacent the rotor.
4. A radial flux electrical machine as claimed in claim 1 or 2, wherein the clutch assembly is actuated between the first and second modes of operation by rotation of the input driveshaft.
5. A radial flux electrical machine as claimed in any one of the preceding claims, wherein the clutch assembly is a freewheel clutch assembly, a trapped roller clutch assembly or a sprag clutch assembly.
6. A radial flux electrical machine as claimed in any one of the preceding claims, wherein relative rotation between the rotor and the input driveshaft in a first direction results in the first mode of operation, and wherein relative rotation between the rotor and the input driveshaft in a second direction results in the second mode of operation.
7. A drivetrain comprising:
a. a radial flux electrical machine as claimed in any one of the preceding claims; b. a secondary power source having an output driveshaft which is attached for rotation with the input driveshaft of the electrical machine,
c. wherein the drivetrain has a first mode of operation in which only the electrical machine supplies torque to the output driveshaft, a second mode of operation in which the electrical machine and the secondary power source supply torque to the output driveshaft.
8. A drivetrain as claimed in claim 7, having a third mode of operation in which the secondary power source drives the electrical machine a generator.
9. A drivetrain as claimed in claim 7 or 8, wherein the secondary power source is an internal combustion engine.
PCT/GB2019/050749 2018-03-21 2019-03-18 Radial flux electrical machines WO2019180410A1 (en)

Applications Claiming Priority (2)

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GB1804491.7A GB2572172A (en) 2018-03-21 2018-03-21 Radial flux electrical machines

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