WO2021091452A1 - An electric machine with an integrated heat exchanger - Google Patents

An electric machine with an integrated heat exchanger Download PDF

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Publication number
WO2021091452A1
WO2021091452A1 PCT/SE2020/051035 SE2020051035W WO2021091452A1 WO 2021091452 A1 WO2021091452 A1 WO 2021091452A1 SE 2020051035 W SE2020051035 W SE 2020051035W WO 2021091452 A1 WO2021091452 A1 WO 2021091452A1
Authority
WO
WIPO (PCT)
Prior art keywords
stator
electric machine
cooling circuit
housing
fluid
Prior art date
Application number
PCT/SE2020/051035
Other languages
French (fr)
Inventor
Christian Ness
Elias BARTOS
Tomas LÖFWALL
Jörgen Engström
Ola Hall
Zoltan Kardos
Original Assignee
Scania Cv Ab
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 Scania Cv Ab filed Critical Scania Cv Ab
Publication of WO2021091452A1 publication Critical patent/WO2021091452A1/en

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Classifications

    • 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
    • H02K1/20—Stationary parts of the magnetic circuit with channels or ducts for flow of cooling medium
    • 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
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/20—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
    • H02K5/203—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium specially adapted for liquids, e.g. cooling jackets
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K9/00—Arrangements for cooling or ventilating
    • H02K9/19—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
    • H02K9/197—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil in which the rotor or stator space is fluid-tight, e.g. to provide for different cooling media for rotor and stator

Definitions

  • the invention relates to an electric machine with an integrated heat exchanger ac cording to the appended claims.
  • the invention further relates to a vehicle comprising such an electric machine according to the appended claims.
  • An electric machine such as a motor or a generator, generates heat when the ma chine is working.
  • the increased temperature will reduce the efficiency and the life span of the electric machine. Therefore, electric machines usually are provided with an external heat exchanger in order to reduce the temperature and thus maintain or increase the efficiency and life span. Heated oil from the electric machine is guided to the external heat exchanger, wherein the temperature of the oil is reduced. Thereaf ter the oil is returned to the electric machine, which will be cooled by the oil with the reduced temperature.
  • Vehicles may be provided with a number of electric machines for different purposes.
  • Document EP 2760113 A1 discloses an oil and water cooled generator motor. Cool ing oil is injected in a space comprising armature windings, a stator and a rotor. The cooling oil will pass the windings and the rotor and be collected in a reservoir situated in the lowermost part of the motor. A cooling waterway is disposed in the housing on the outer periphery of the stator. Both the cooling oil and cooling water are cooled in external coolers.
  • Document JP 2013-162674 A discloses an oil and water cooled generator motor. Cooling oil is circulated in a space comprising armature windings, a stator and a ro tor.
  • the cooling oil will flow in a channel arranged in a housing, pass the windings, bearings of the rotor and be collected in a reservoir situated in the lowermost part of the motor.
  • a cooling waterway is disposed in the housing outside of the oil channel in the housing. The cooling water is cooled in an external cooler.
  • the windings in the electric machine generates a significant portion of heat in opera tion of the machine.
  • the windings are arranged in the stator, and the generated heat is transferred from the windings to the stator. Since the stator of the electric machine is a component of significant weight and mass, heat will be accumulated in stator. The increased temperature in the stator and also in other components of the electric machine will reduce the efficiency and the life span of the electric machine.
  • An object of the invention is therefore to effectively reduce the temperature of an electric machine to an acceptable or desired operation temperature.
  • a further object of the invention is to effectively reduce the temperature of a stator in an electric machine.
  • the electric machine comprising a rotor and a stator, which stator at least partly surrounds the rotor; and a housing, which is configured to cir cumferentially enclose the stator; wherein the heat exchanger comprising a first cool ing circuit arranged in the housing; a wall of the housing configured to create an inter face between the stator and the first cooling circuit in the housing; and a second cool ing circuit arranged at least partly in the stator; wherein the housing is configured to abut against an outer circumference of the stator, so that heat from a second fluid in the second cooling circuit is configured to be transferred through the interface be tween the stator and the housing, and further to a first fluid in the first cooling circuit.
  • a vehicle comprising the electric machine with an integrated heat exchanger disclosed herein.
  • the temperature of the electric machine is effectively reduced to a desired operation temperature of the electric machine.
  • the temperature of the stator in the electric machine is effectively reduced to reach an operation temperature of the elec tric machine. Due to the integrated heat exchanger in the electric machine, a mini mum of external cooling components are used, which will reduce costs and weight of the machine.
  • the desired operation temperature of an electric machine may be in the temperature range of 40°C - 70°C.
  • Fig. 1 schematically illustrates a side view of a vehicle with an electric machine with an integrated heat exchanger according to an example
  • Fig. 2 schematically illustrates a section view of an electric machine with an integrated heat exchanger according to an example
  • Fig. 3 schematically illustrates a section view in part of stator according to an example.
  • An electric machine with an integrated heat exchanger and a vehicle comprising such an electric machine with an integrated heat exchanger according to the present dis closure ensures that the temperature of the electric machine is effectively reduced to a desired operation temperature of the electric machine.
  • the temperature of a stator in the electric machine is effectively reduced to reach the desired opera tion temperature of the electric machine. Due to the integrated heat exchanger in the electric machine, a minimum of external cooling components are used, which will re Jerusalem costs and weight of the machine.
  • the desired operation temperature of an elec tric machine may be in the temperature range of 40°C - 70°C, wherein the efficiency and the life span of the electric machine will be optimal.
  • an electric machine with an integrated heat ex changer comprising a rotor and a stator, which sta tor at least partly surrounds the rotor; and a housing, which is configured to circum ferentially enclose the stator; wherein the heat exchanger comprising a first cooling circuit arranged in the housing; a wall of the housing configured to create an interface between the stator and the first cooling circuit in the housing; and a second cooling circuit arranged at least partly in the stator; wherein the housing is configured to abut against an outer circumference of the stator, so that heat from a second fluid in the second cooling circuit is configured to be transferred through the interface between the stator and the housing, and further to a first fluid in the first cooling circuit.
  • the electric machine may be an electric motor or an electric generator or a combined electric motor and generator.
  • the electric machine is able to generate rotational speed and torque when feeding the electric machine with electric power from an electric power source, such as an energy storage unit, such as a battery.
  • the electric machine is able to generate electric power when torque from an external source generates rotational speed of the rotor of the electric machine.
  • the electric machine may generate electric power to the energy storage unit, such as a battery.
  • the electric machine may be any type of electric machine, such as a di rect current (DC) electric machine or an alternate current (AC) electric machine.
  • the integrated heat exchanger is primarily arranged within the electric machine and is a part of the components of the electric machine.
  • the heat exchanger is arranged to transfer heat between the first and second fluid.
  • the first and second fluids are separated from each other in the heat exchanger.
  • the rotor is rotatable arranged in the electric machine.
  • the rotor is configured to ro tate about a rotor shaft, which is arranged in bearings in the housing of the electric machine.
  • the rotor has a circular configuration and an axial extension.
  • the stator is provided with windings in which an electric field is generated during op eration of the electric machine.
  • the electric field generated in the windings will gener ate heat in the electric machine.
  • the stator at least partly surrounds the rotor.
  • the stator has an inner circular configuration with an inner diameter which is larger than the outer diameter of the rotor.
  • An outer wall of the stator may have a circular config uration or another shape.
  • the stator at least partly surrounds the rotor.
  • the sta tor may have a shorter axial extension than the axial extension of the rotor.
  • the housing is configured to circumferentially enclose the stator.
  • the housing may be an inner housing or an outer housing of the electric machine.
  • the housing may also be a combined inner and outer housing.
  • An inner wall of the housing is config ured to abut the outer wall of the stator.
  • the inner wall of the housing may thus be configured to follow the shape of the outer wall of the stator.
  • the shape of the outer wall of the stator may correspond to the inner shape of the wall of the housing.
  • the outer wall of the stator may have a circular configuration or another shape. Therefore, the shape of the inner wall of the housing may have a cir cular configuration or another shape, depending on the shape of the outer wall of the stator.
  • the first cooling circuit is at least partly arranged in the housing.
  • the first cooling circuit may comprise channels arranged in the housing.
  • the channels may extend in a circumferentially or in an axially direction in the housing in relation to the axial exten sion of the electric machine. Alternatively, the channels may extend both circumfer entially and axially in the housing.
  • the first cooling circuit is a part of the integrated heat exchanger in the electric machine.
  • the wall of the housing which is configured to create an interface between the stator and the first cooling circuit in the housing, may be the inner wall of the housing.
  • the wall of the housing, which is directed towards the stator is configured to abut the wall of the stator.
  • the wall of the housing may thus be configured to follow the shape of the wall of the stator, facing the wall of the housing.
  • the shape of the wall of the stator facing the wall of the housing may correspond to the shape of the wall of the housing.
  • the area of the wall of the housing that faces the stator comprises the inter face between the stator and the first cooling circuit in the housing.
  • that area of the stator, which faces the wall of the housing comprises the interface.
  • the integrated heat exchanger in the electric machine comprises the interface between the stator and the first cooling circuit. Thus, in the integrated heat exchanger heat is transferred through the interface.
  • the second cooling circuit is arranged at least partly in the stator.
  • the second cool ing circuit may comprise channels arranged in the stator.
  • the channels may extend in a circumferentially or in an axially direction in the stator in relation to the axial ex tension of the electric machine. Alternatively, the channels may extend both circum ferentially and axially in the stator.
  • the second cooling circuit is a part of the inte grated heat exchanger in the electric machine.
  • the first fluid may be water, which is arranged to flow within the first cooling circuit in the housing.
  • Other fluids than water are possible to arrange to flow within the first cooling circuit, such as oil, a powder or any other type of coolant.
  • a combination of different fluids are possible to arrange to flow within the first cooling circuit.
  • the second fluid may be oil, which is arranged to flow within the second cooling cir cuit in the stator.
  • Other fluids than oil are possible to arrange to flow within the sec ond cooling circuit.
  • a combination of different fluids are possible to arrange to flow within the second cooling circuit.
  • Heat generated in the electric machine is transferred to the second fluid.
  • the heat in the second fluid in the second cooling circuit is configured to be transferred through the interface between the stator and the housing, and further to a first fluid in the first cooling circuit.
  • the stator comprises discs arranged to form the second cooling circuit in the stator.
  • the discs are arranged beside each other in the axially direction of the electric ma chine.
  • the axially arranged discs together create a stack of discs and will together create the shape of the stator.
  • the discs may have a similar shape.
  • the discs may have apertures between a center axis and the periphery of the disc and/or apertures in the periphery of the discs.
  • the apertures in the discs may create spaces or chan nels in the stack of discs, which spaces or channels creates the second cooling cir cuit in the stator.
  • Some of the discs may be differently arranged in the stack by pivot ing them some degrees in relation to other discs in the stack.
  • the stator comprises at least two sets of discs of different configuration, wherein the at least two sets of discs of different configuration together form the second cooling circuit.
  • Some of the discs may have a different shape than other discs in the stack, so that the discs of different shape together create the second cooling circuit in the stator.
  • Some of the discs may have apertures between a center axis and the periphery of the disc and/or apertures in the periphery of the discs. The apertures in the discs may create spaces or channels in the stack of discs, which spaces or channels cre ates the second cooling circuit in the stator.
  • the second cooling circuit is arranged at least partly in the outer circumference of the stator.
  • the discs may be provided with apertures in the periphery.
  • the apertures in the pe riphery of the discs will create spaces or channels in the stack of discs, which spaces or channels creates the second cooling circuit in the stator.
  • Arranging the second cooling circuit at least partly in the outer circumference of the stator will improve the transfer of heat from the second fluid in the second cooling circuit through the inter face and to the first fluid in the first cooling circuit.
  • the part of the second cooling circuit which is arranged in the outer circumference of the stator extends in a circumferentially direction of the stator.
  • the exposed area of the second cooling circuit to the interface and the first cooling circuit will be large, which will increase the heat transfer between the cooling circuits.
  • the part of the second cooling circuit which is arranged in the outer circumference of the stator, comprises a plurality of channels extending in parallel.
  • a parallel configuration of the channels of the second cooling circuit in the stator will create a large exposed area of the channels and the second cooling circuit to the in terface and the first cooling circuit, which will increase the heat transfer between the cooling circuits.
  • the plurality of channels extending in parallel are con nected with each other, so that the second fluid is allowed to flow from one channel to another channel.
  • connection of the channels may be so arranged that the direction of flow of the second fluid will be different between the channels of the second cooling circuit. This will increase the heat transfer between the first and second cooling circuits.
  • the interface between the stator and the housing is config ured to at least partly form a wall portion of the second cooling circuit, so that the second fluid in the second cooling circuit is configured to have physical contact with the interface.
  • Arranging the second cooling circuit in the outer wall of the stator will create a chan nels with walls combined of the inner wall of the housing and the outer wall of the sta tor.
  • the housing and the stator together will create the shape of the second cooling circuit.
  • the second fluid in the second cooling circuit is configured to have physical contact directly with the interface, the heat transfer between the first and second cooling circuits will increase.
  • the second cooling circuit is arranged at least partly in an axial direction of the stator.
  • the second cooling circuit comprises channels that may extend at least partly in an axial direction of the stator and thus the axial direction of electric machine. Such axial extending channels may guide the second fluid to other parts of the second cooling circuit, such as the part of the second cooling circuit that extend in a circumferentially direction of the stator.
  • turbulating elements are arranged in the second cooling circuit, which turbulating elements are configured for creating a turbulent flow of the second fluid in the second cooling circuit.
  • the turbulating elements may be a separate component arranged in the second cool ing circuit.
  • the turbulating elements may have the shape of a circular pin or piece of a flat panel.
  • the turbulating elements disturb the laminate flow of the second fluid.
  • the turbulent flow of the second fluid in the second cooling circuit which is created by the turbulating elements, increases the heat transfer between the first and second cooling circuits
  • the turbulating elements are configured by a portion of at least one disc of the stator.
  • the turbulating elements may be configured by the discs of the stator.
  • a vehicle comprising the electric machine with an integrated heat exchanger disclosed herein.
  • the electric machine may be a propulsion unit in the vehicle.
  • the electric machine may be connected to a power source in the vehicle, such as energy storage unit. During some driving conditions of the vehicle, the electric machine may generate electric power to the energy storage unit.
  • the vehicle may also be provided with a range ex tender.
  • Such a range extender may be a small internal combustion engine, which is connected to a generator in order to charge energy storage units, such as batteries.
  • the first cooling circuit may be connected to a first fluid pump for creating a flow within the first cooling circuit.
  • the first cooling circuit may also be connected to an ex ternal cooler for reducing the temperature of the first fluid.
  • the second cooling circuit may be connected to a second fluid pump for creating a flow within the second cool ing circuit.
  • Fig. 1 schematically illustrates a side view of a vehicle 1 with an electric machine 3 with an integrated heat exchanger 12 according to an example.
  • the electric machine 3 is arranged in a powertrain 2 of the vehicle 1 .
  • the powertrain 2 also comprises an internal combustion engine 4, a transmission 6 connected to the electric machine 4 and to a propeller shaft 8.
  • the propeller shaft 8 extends between the transmission 6 and drive wheels 10 of the vehicle 1 .
  • the electric machine 4 and the internal com bustion engine 4 are propulsion units in the powertrain 2.
  • the vehicle 1 may be provided only with electric machines 3 as propulsion units.
  • An energy storage unit 14 is arranged in the powertrain 2.
  • the energy storage unit 14 is connected to the electric machine 3.
  • Fig. 2 schematically illustrates a section view of an electric machine 3 with an inte grated heat exchanger 12 according to an example.
  • the electric machine 3 com prises a rotor 16 and a stator 18, which stator 18 surrounds the rotor 16.
  • the rotor 16 is rotatably arranged on a rotor shaft 19.
  • a housing 20 is configured to circumferen tially enclose the stator 18.
  • the heat exchanger 12 comprising a first cooling circuit 22 arranged in the housing 20.
  • a wall 24 of the housing 20 is configured to create an interface 26 between the stator 18 and the first cooling circuit 22 in the housing 20.
  • a second cooling circuit 28 is partly arranged in the stator 18.
  • the housing 20 is config ured to abut against an outer circumference of the stator 18, so that heat from a sec ond fluid 30 in the second cooling circuit 28 is configured to be transferred through the interface 26 between the stator 18 and the housing 20, and further to a first fluid 32 in the first cooling circuit 22.
  • the interface 26 between the stator 18 and the hous ing 20 is configured to at least partly form a wall portion 38 of the second cooling cir cuit 28, so that the second fluid 30 in the second cooling circuit 28 is configured to have physical contact with the interface 26.
  • the first cooling circuit 22 is connected to a first fluid pump 44 for creating a fluid flow within the first cooling circuit 22.
  • the first cooling circuit 22 may also be connected to an external cooler 46 for reducing the temperature of the first fluid 32.
  • the second cooling circuit 28 may be connected to a second fluid pump 48 for creating a flow within the second cooling circuit 28.
  • the flow path and flow directions of the first and second fluids are indicated with arrows in fig. 2.
  • Fig. 3 schematically illustrates a section view in part of stator 18 according to an ex ample.
  • the stator 18 comprises discs 34 arranged to form the second cooling circuit 28 in the stator 18.
  • the discs 34 may have a similar shape. Some of the discs 34 may be differently arranged in relation to each other. By pivoting the discs 34 some degrees in relation to one other, apertures in the respective discs 34 creates the shape of the second cooling circuit 28 in the stator 18.
  • the stator 18 may comprise at least two sets of discs 34 of different configuration, wherein the at least two sets of discs 34 of differ ent configuration together form the second cooling circuit 28.
  • the second cooling cir cuit 28 is partly arranged in the outer circumference of the stator 18, wherein the part of the second cooling circuit 28, which is arranged in the outer circumference of the stator 18 extends in a circumferentially direction of the stator 18.
  • the part of the second cooling circuit 28, which is arranged in the outer circumference of the stator 18, com prises a plurality of channels 36 extending in parallel.
  • the plurality of channels 36 ex tending in parallel are connected with each other, so that the second fluid 30 is allowed to flow from one channel 36 to another channel 36.
  • the second cooling circuit 28 is also arranged at least partly in an axial direction of the stator 18.
  • Turbulating elements 40 are arranged in the second cooling circuit 28, which turbulating elements 40 are configured for creating a turbulent flow of the second fluid 30 (fig. 2) in the second cooling circuit 28.
  • the turbulating elements 40 are configured by a portion 42 of at least one disc 34 of the stator 18.

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

Abstract

The invention relates to an electric machine (3) with an integrated heat exchanger (12), the electric machine (3) comprising a rotor (16) and a stator (18), which stator (16) at least partly surrounds the rotor (16); and a housing (20), which is configured to circumferentially enclose the stator (18); wherein the heat exchanger (12) comprising a first cooling circuit (22) arranged in the housing (20); a wall (24) of the housing (20) configured to create an interface (26) between the stator (18) and the first cool- ing circuit (22) in the housing (20); and a second cooling circuit (28) arranged at least partly in the stator (18); wherein the housing (20) is configured to abut against an outer circumference of the stator (18), so that heat from a second fluid (30) in the second cooling circuit (28) is configured to be transferred through the interface (26) between the stator (18) and the housing (20), and further to a first fluid (32) in the first cooling circuit (22). The invention also relates to a vehicle (1) comprising an electric machine (3) with an integrated heat exchanger (12).

Description

An electric machine with an integrated heat exchanger
TECHNICAL FIELD
The invention relates to an electric machine with an integrated heat exchanger ac cording to the appended claims. The invention further relates to a vehicle comprising such an electric machine according to the appended claims.
BACKGROUND
An electric machine, such as a motor or a generator, generates heat when the ma chine is working. The increased temperature will reduce the efficiency and the life span of the electric machine. Therefore, electric machines usually are provided with an external heat exchanger in order to reduce the temperature and thus maintain or increase the efficiency and life span. Heated oil from the electric machine is guided to the external heat exchanger, wherein the temperature of the oil is reduced. Thereaf ter the oil is returned to the electric machine, which will be cooled by the oil with the reduced temperature.
There are some electric machines, which are provided with a water cooling circuit in the housing of the electric machine. Generated heat in the housing is transferred to the cooling water in the water cooling circuit. The heated cooling water is guided to an external water cooler, wherein the temperature of the water is reduced. Thereafter the cooling water is returned to the housing of the electric machine.
Vehicles may be provided with a number of electric machines for different purposes.
Document EP 2760113 A1 discloses an oil and water cooled generator motor. Cool ing oil is injected in a space comprising armature windings, a stator and a rotor. The cooling oil will pass the windings and the rotor and be collected in a reservoir situated in the lowermost part of the motor. A cooling waterway is disposed in the housing on the outer periphery of the stator. Both the cooling oil and cooling water are cooled in external coolers. Document JP 2013-162674 A discloses an oil and water cooled generator motor. Cooling oil is circulated in a space comprising armature windings, a stator and a ro tor. The cooling oil will flow in a channel arranged in a housing, pass the windings, bearings of the rotor and be collected in a reservoir situated in the lowermost part of the motor. A cooling waterway is disposed in the housing outside of the oil channel in the housing. The cooling water is cooled in an external cooler.
SUMMARY
The windings in the electric machine generates a significant portion of heat in opera tion of the machine. The windings are arranged in the stator, and the generated heat is transferred from the windings to the stator. Since the stator of the electric machine is a component of significant weight and mass, heat will be accumulated in stator. The increased temperature in the stator and also in other components of the electric machine will reduce the efficiency and the life span of the electric machine.
Therefore, it is desired to effectively reduce the temperature of an electric machine to an acceptable or desired operation temperature.
In addition, it is desired to effectively reduce the temperature of a stator in an electric machine.
An object of the invention is therefore to effectively reduce the temperature of an electric machine to an acceptable or desired operation temperature.
A further object of the invention is to effectively reduce the temperature of a stator in an electric machine.
The herein mentioned objects are achieved with an electric machine with an inte grated heat exchanger according to the appended claims. The herein mentioned ob jects are also achieved with a vehicle provided with such an electric machine accord ing to the appended claims. According to an aspect of the invention, an electric machine with an integrated heat exchanger is provided. The electric machine comprising a rotor and a stator, which stator at least partly surrounds the rotor; and a housing, which is configured to cir cumferentially enclose the stator; wherein the heat exchanger comprising a first cool ing circuit arranged in the housing; a wall of the housing configured to create an inter face between the stator and the first cooling circuit in the housing; and a second cool ing circuit arranged at least partly in the stator; wherein the housing is configured to abut against an outer circumference of the stator, so that heat from a second fluid in the second cooling circuit is configured to be transferred through the interface be tween the stator and the housing, and further to a first fluid in the first cooling circuit.
According to a further aspect of the invention, a vehicle is provided. The vehicle, comprising the electric machine with an integrated heat exchanger disclosed herein.
By such electric machine with an integrated heat exchanger and by such a vehicle, the temperature of the electric machine is effectively reduced to a desired operation temperature of the electric machine. In addition, the temperature of the stator in the electric machine is effectively reduced to reach an operation temperature of the elec tric machine. Due to the integrated heat exchanger in the electric machine, a mini mum of external cooling components are used, which will reduce costs and weight of the machine. The desired operation temperature of an electric machine may be in the temperature range of 40°C - 70°C.
Additional objectives, advantages and novel features of the invention will be apparent to one skilled in the art from the following details, and through exercising the invention. While the invention is described below, it should be apparent that the invention may not be limited to the specifically described details. One skilled in the art, having access to the teachings herein, will recognize additional applications, modifications and incor porations in other areas, which are within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS
For fuller understanding of the present disclosure and further objects and advantages of it, the detailed description set out below should be read together with the accompa nying drawings, in which the same reference notations denote similar items in the var ious figures, and in which:
Fig. 1 schematically illustrates a side view of a vehicle with an electric machine with an integrated heat exchanger according to an example;
Fig. 2 schematically illustrates a section view of an electric machine with an integrated heat exchanger according to an example; and
Fig. 3 schematically illustrates a section view in part of stator according to an example.
DETAILED DESCRIPTION
An electric machine with an integrated heat exchanger and a vehicle comprising such an electric machine with an integrated heat exchanger according to the present dis closure ensures that the temperature of the electric machine is effectively reduced to a desired operation temperature of the electric machine. In addition, the temperature of a stator in the electric machine is effectively reduced to reach the desired opera tion temperature of the electric machine. Due to the integrated heat exchanger in the electric machine, a minimum of external cooling components are used, which will re duce costs and weight of the machine. The desired operation temperature of an elec tric machine may be in the temperature range of 40°C - 70°C, wherein the efficiency and the life span of the electric machine will be optimal.
According to the present disclosure, an electric machine with an integrated heat ex changer is provided. The electric machine comprising a rotor and a stator, which sta tor at least partly surrounds the rotor; and a housing, which is configured to circum ferentially enclose the stator; wherein the heat exchanger comprising a first cooling circuit arranged in the housing; a wall of the housing configured to create an interface between the stator and the first cooling circuit in the housing; and a second cooling circuit arranged at least partly in the stator; wherein the housing is configured to abut against an outer circumference of the stator, so that heat from a second fluid in the second cooling circuit is configured to be transferred through the interface between the stator and the housing, and further to a first fluid in the first cooling circuit.
The electric machine may be an electric motor or an electric generator or a combined electric motor and generator. Thus, the electric machine is able to generate rotational speed and torque when feeding the electric machine with electric power from an electric power source, such as an energy storage unit, such as a battery. In addition, the electric machine is able to generate electric power when torque from an external source generates rotational speed of the rotor of the electric machine. As a genera tor, the electric machine may generate electric power to the energy storage unit, such as a battery. The electric machine may be any type of electric machine, such as a di rect current (DC) electric machine or an alternate current (AC) electric machine.
The integrated heat exchanger is primarily arranged within the electric machine and is a part of the components of the electric machine. The heat exchanger is arranged to transfer heat between the first and second fluid. The first and second fluids are separated from each other in the heat exchanger.
The rotor is rotatable arranged in the electric machine. The rotor is configured to ro tate about a rotor shaft, which is arranged in bearings in the housing of the electric machine. The rotor has a circular configuration and an axial extension.
The stator is provided with windings in which an electric field is generated during op eration of the electric machine. The electric field generated in the windings will gener ate heat in the electric machine. The stator at least partly surrounds the rotor. The stator has an inner circular configuration with an inner diameter which is larger than the outer diameter of the rotor. An outer wall of the stator may have a circular config uration or another shape. The stator at least partly surrounds the rotor. Thus, the sta tor may have a shorter axial extension than the axial extension of the rotor. The housing is configured to circumferentially enclose the stator. The housing may be an inner housing or an outer housing of the electric machine. The housing may also be a combined inner and outer housing. An inner wall of the housing is config ured to abut the outer wall of the stator. The inner wall of the housing may thus be configured to follow the shape of the outer wall of the stator. Thus, the shape of the outer wall of the stator may correspond to the inner shape of the wall of the housing. As mentioned above, the outer wall of the stator may have a circular configuration or another shape. Therefore, the shape of the inner wall of the housing may have a cir cular configuration or another shape, depending on the shape of the outer wall of the stator.
The first cooling circuit is at least partly arranged in the housing. The first cooling cir cuit may comprise channels arranged in the housing. The channels may extend in a circumferentially or in an axially direction in the housing in relation to the axial exten sion of the electric machine. Alternatively, the channels may extend both circumfer entially and axially in the housing. The first cooling circuit is a part of the integrated heat exchanger in the electric machine.
The wall of the housing, which is configured to create an interface between the stator and the first cooling circuit in the housing, may be the inner wall of the housing. The wall of the housing, which is directed towards the stator is configured to abut the wall of the stator. The wall of the housing may thus be configured to follow the shape of the wall of the stator, facing the wall of the housing. Thus, the shape of the wall of the stator facing the wall of the housing may correspond to the shape of the wall of the housing. The area of the wall of the housing that faces the stator comprises the inter face between the stator and the first cooling circuit in the housing. In addition, that area of the stator, which faces the wall of the housing comprises the interface. The integrated heat exchanger in the electric machine comprises the interface between the stator and the first cooling circuit. Thus, in the integrated heat exchanger heat is transferred through the interface.
The second cooling circuit is arranged at least partly in the stator. The second cool ing circuit may comprise channels arranged in the stator. The channels may extend in a circumferentially or in an axially direction in the stator in relation to the axial ex tension of the electric machine. Alternatively, the channels may extend both circum ferentially and axially in the stator. The second cooling circuit is a part of the inte grated heat exchanger in the electric machine.
The first fluid may be water, which is arranged to flow within the first cooling circuit in the housing. Other fluids than water are possible to arrange to flow within the first cooling circuit, such as oil, a powder or any other type of coolant. Also, a combination of different fluids are possible to arrange to flow within the first cooling circuit.
The second fluid may be oil, which is arranged to flow within the second cooling cir cuit in the stator. Other fluids than oil are possible to arrange to flow within the sec ond cooling circuit. Also, a combination of different fluids are possible to arrange to flow within the second cooling circuit.
Heat generated in the electric machine is transferred to the second fluid. The heat in the second fluid in the second cooling circuit is configured to be transferred through the interface between the stator and the housing, and further to a first fluid in the first cooling circuit.
According to an example, the stator comprises discs arranged to form the second cooling circuit in the stator.
The discs are arranged beside each other in the axially direction of the electric ma chine. The axially arranged discs together create a stack of discs and will together create the shape of the stator. The discs may have a similar shape. The discs may have apertures between a center axis and the periphery of the disc and/or apertures in the periphery of the discs. The apertures in the discs may create spaces or chan nels in the stack of discs, which spaces or channels creates the second cooling cir cuit in the stator. Some of the discs may be differently arranged in the stack by pivot ing them some degrees in relation to other discs in the stack. When pivoting some of the discs, the apertures in the respective discs creates the shape of the second cool ing circuit in the stator. According to an example, the stator comprises at least two sets of discs of different configuration, wherein the at least two sets of discs of different configuration together form the second cooling circuit.
Some of the discs may have a different shape than other discs in the stack, so that the discs of different shape together create the second cooling circuit in the stator. Some of the discs may have apertures between a center axis and the periphery of the disc and/or apertures in the periphery of the discs. The apertures in the discs may create spaces or channels in the stack of discs, which spaces or channels cre ates the second cooling circuit in the stator.
According to an example, the second cooling circuit is arranged at least partly in the outer circumference of the stator.
The discs may be provided with apertures in the periphery. The apertures in the pe riphery of the discs will create spaces or channels in the stack of discs, which spaces or channels creates the second cooling circuit in the stator. Arranging the second cooling circuit at least partly in the outer circumference of the stator will improve the transfer of heat from the second fluid in the second cooling circuit through the inter face and to the first fluid in the first cooling circuit.
According to an example, the part of the second cooling circuit, which is arranged in the outer circumference of the stator extends in a circumferentially direction of the stator.
By arranging the second cooling circuit in a circumferentially direction of the stator, the exposed area of the second cooling circuit to the interface and the first cooling circuit will be large, which will increase the heat transfer between the cooling circuits.
According to an example, the part of the second cooling circuit, which is arranged in the outer circumference of the stator, comprises a plurality of channels extending in parallel. A parallel configuration of the channels of the second cooling circuit in the stator will create a large exposed area of the channels and the second cooling circuit to the in terface and the first cooling circuit, which will increase the heat transfer between the cooling circuits.
According to an example, the plurality of channels extending in parallel are con nected with each other, so that the second fluid is allowed to flow from one channel to another channel.
The connection of the channels may be so arranged that the direction of flow of the second fluid will be different between the channels of the second cooling circuit. This will increase the heat transfer between the first and second cooling circuits.
According to an example, the interface between the stator and the housing is config ured to at least partly form a wall portion of the second cooling circuit, so that the second fluid in the second cooling circuit is configured to have physical contact with the interface.
Arranging the second cooling circuit in the outer wall of the stator will create a chan nels with walls combined of the inner wall of the housing and the outer wall of the sta tor. Thus, the housing and the stator together will create the shape of the second cooling circuit. When the second fluid in the second cooling circuit is configured to have physical contact directly with the interface, the heat transfer between the first and second cooling circuits will increase.
According to an example, the second cooling circuit is arranged at least partly in an axial direction of the stator.
The second cooling circuit comprises channels that may extend at least partly in an axial direction of the stator and thus the axial direction of electric machine. Such axial extending channels may guide the second fluid to other parts of the second cooling circuit, such as the part of the second cooling circuit that extend in a circumferentially direction of the stator. According to an example, turbulating elements are arranged in the second cooling circuit, which turbulating elements are configured for creating a turbulent flow of the second fluid in the second cooling circuit.
The turbulating elements may be a separate component arranged in the second cool ing circuit. The turbulating elements may have the shape of a circular pin or piece of a flat panel. The turbulating elements disturb the laminate flow of the second fluid. The turbulent flow of the second fluid in the second cooling circuit, which is created by the turbulating elements, increases the heat transfer between the first and second cooling circuits
According to an example, the turbulating elements are configured by a portion of at least one disc of the stator.
Alternatively, or in combination with separate component arranged in the second cooling circuit, the turbulating elements may be configured by the discs of the stator. The turbulent flow of the second fluid in the second cooling circuit, which is created by the turbulating elements, increase the heat transfer between the first and second cooling circuits
According to the present disclosure, a vehicle is provided. The vehicle, comprising the electric machine with an integrated heat exchanger disclosed herein.
A vehicle provided with such an electric machine with an integrated heat exchanger will benefit from the high efficiency and long life span of the electric machine. The electric machine may be a propulsion unit in the vehicle. The electric machine may be connected to a power source in the vehicle, such as energy storage unit. During some driving conditions of the vehicle, the electric machine may generate electric power to the energy storage unit. The vehicle may also be provided with a range ex tender. Such a range extender may be a small internal combustion engine, which is connected to a generator in order to charge energy storage units, such as batteries. The first cooling circuit may be connected to a first fluid pump for creating a flow within the first cooling circuit. The first cooling circuit may also be connected to an ex ternal cooler for reducing the temperature of the first fluid. The second cooling circuit may be connected to a second fluid pump for creating a flow within the second cool ing circuit.
The present disclosure will now, according to an example, be further illustrated with reference to the appended figures.
Fig. 1 schematically illustrates a side view of a vehicle 1 with an electric machine 3 with an integrated heat exchanger 12 according to an example. The electric machine 3 is arranged in a powertrain 2 of the vehicle 1 . The powertrain 2 also comprises an internal combustion engine 4, a transmission 6 connected to the electric machine 4 and to a propeller shaft 8. The propeller shaft 8 extends between the transmission 6 and drive wheels 10 of the vehicle 1 . The electric machine 4 and the internal com bustion engine 4 are propulsion units in the powertrain 2. However, the vehicle 1 may be provided only with electric machines 3 as propulsion units. An energy storage unit 14 is arranged in the powertrain 2. The energy storage unit 14 is connected to the electric machine 3.
Fig. 2 schematically illustrates a section view of an electric machine 3 with an inte grated heat exchanger 12 according to an example. The electric machine 3 com prises a rotor 16 and a stator 18, which stator 18 surrounds the rotor 16. The rotor 16 is rotatably arranged on a rotor shaft 19. A housing 20 is configured to circumferen tially enclose the stator 18. The heat exchanger 12 comprising a first cooling circuit 22 arranged in the housing 20. A wall 24 of the housing 20 is configured to create an interface 26 between the stator 18 and the first cooling circuit 22 in the housing 20. A second cooling circuit 28 is partly arranged in the stator 18. The housing 20 is config ured to abut against an outer circumference of the stator 18, so that heat from a sec ond fluid 30 in the second cooling circuit 28 is configured to be transferred through the interface 26 between the stator 18 and the housing 20, and further to a first fluid 32 in the first cooling circuit 22. The interface 26 between the stator 18 and the hous ing 20 is configured to at least partly form a wall portion 38 of the second cooling cir cuit 28, so that the second fluid 30 in the second cooling circuit 28 is configured to have physical contact with the interface 26. The first cooling circuit 22 is connected to a first fluid pump 44 for creating a fluid flow within the first cooling circuit 22. The first cooling circuit 22 may also be connected to an external cooler 46 for reducing the temperature of the first fluid 32. The second cooling circuit 28 may be connected to a second fluid pump 48 for creating a flow within the second cooling circuit 28. The flow path and flow directions of the first and second fluids are indicated with arrows in fig. 2.
Fig. 3 schematically illustrates a section view in part of stator 18 according to an ex ample. The stator 18 comprises discs 34 arranged to form the second cooling circuit 28 in the stator 18. The discs 34 may have a similar shape. Some of the discs 34 may be differently arranged in relation to each other. By pivoting the discs 34 some degrees in relation to one other, apertures in the respective discs 34 creates the shape of the second cooling circuit 28 in the stator 18. The stator 18 may comprise at least two sets of discs 34 of different configuration, wherein the at least two sets of discs 34 of differ ent configuration together form the second cooling circuit 28. The second cooling cir cuit 28 is partly arranged in the outer circumference of the stator 18, wherein the part of the second cooling circuit 28, which is arranged in the outer circumference of the stator 18 extends in a circumferentially direction of the stator 18. The part of the second cooling circuit 28, which is arranged in the outer circumference of the stator 18, com prises a plurality of channels 36 extending in parallel. The plurality of channels 36 ex tending in parallel are connected with each other, so that the second fluid 30 is allowed to flow from one channel 36 to another channel 36. The second cooling circuit 28 is also arranged at least partly in an axial direction of the stator 18. Turbulating elements 40 are arranged in the second cooling circuit 28, which turbulating elements 40 are configured for creating a turbulent flow of the second fluid 30 (fig. 2) in the second cooling circuit 28. The turbulating elements 40 are configured by a portion 42 of at least one disc 34 of the stator 18.
The foregoing description of the examples has been furnished for illustrative and de scriptive purposes. It is not intended to be exhaustive, or to limit the examples to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The examples have been chosen and described in order to best explicate principles and practical applications, and to thereby enable one skilled in the art to understand the examples in terms of its various examples and with the vari ous modifications that are applicable to its intended use. The components and fea tures specified above may, within the framework of the examples, be combined be tween different examples specified.

Claims

1. An electric machine (3) with an integrated heat exchanger (12), the electric ma chine (3) comprising a rotor (16) and a stator (18), which stator (16) at least partly surrounds the ro tor (16); and a housing (20), which is configured to circumferentially enclose the stator (18); wherein the heat exchanger (12) comprising a first cooling circuit (22) arranged in the housing (20); a wall (24) of the housing (20) configured to create an interface (26) between the stator (18) and the first cooling circuit (22) in the housing (20); and a second cooling circuit (28) arranged at least partly in the stator (18); wherein the housing (20) is configured to abut against an outer circumference of the stator (18), so that heat from a second fluid (30) in the second cooling circuit (28) is configured to be transferred through the interface (26) between the stator (18) and the housing (20), and further to a first fluid (32) in the first cooling circuit (22).
2. The electric machine (3) according to claim 1 , wherein the stator (18) comprises discs (34) arranged to form the second cooling circuit (28) in the stator (18).
3. The electric machine (3) according to any one of claims 1 and 2, wherein the stator (4) comprises at least two sets of discs (18) of different configuration, wherein the at least two sets of discs (18) of different configuration together form the second cooling circuit (28).
4. The electric machine (3) according to any one of the preceding claims, wherein the second cooling circuit (28) is arranged at least partly in the outer circumference of the stator (18).
5. The electric machine (3) according to claim 4, wherein the part of the second cool ing circuit (28), which is arranged in the outer circumference of the stator (18) ex tends in a circumferentially direction of the stator (18).
6. The electric machine (3) according to any one of claims 4 and 5, wherein the part of the second cooling circuit (22), which is arranged in the outer circumference of the stator (18), comprises a plurality of channels (36) extending in parallel.
7. The electric machine (3) according to claim 6, wherein the plurality of channels (36) extending in parallel are connected with each other, so that the second fluid (30) is allowed to flow from one channel (36) to another channel (36).
8. The electric machine (3) according to any one of the preceding claims, wherein the interface (26) between the stator (18) and the housing (20) is configured to at least partly form a wall portion (38) of the second cooling circuit (22), so that the second fluid (30) in the second cooling circuit (22) is configured to have physical contact with the interface (26).
9. The electric machine (3) according to any one of the preceding claims, wherein the second cooling circuit (22) is arranged at least partly in an axial direction of the stator (18).
10. The electric machine (3) according to any one of the preceding claims, wherein turbulating elements (40) are arranged in the second cooling circuit (22), which tabu lating elements (40) are configured for creating a turbulent flow of the second fluid (30) in the second cooling circuit (22).
11. The electric machine (3) according to claim 10, wherein the turbulating elements (40) are configured by a portion (42) of at least one disc (34) of the stator (18).
12. A vehicle (1), comprising an electric machine (3) with an integrated heat ex changer (12) according to any one of the preceding claims.
PCT/SE2020/051035 2019-11-05 2020-10-27 An electric machine with an integrated heat exchanger WO2021091452A1 (en)

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