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GB2599616A - Liquid cooled electric motor - Google Patents

Liquid cooled electric motor Download PDF

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Publication number
GB2599616A
GB2599616A GB2010699.3A GB202010699A GB2599616A GB 2599616 A GB2599616 A GB 2599616A GB 202010699 A GB202010699 A GB 202010699A GB 2599616 A GB2599616 A GB 2599616A
Authority
GB
United Kingdom
Prior art keywords
housing
pump
cooling block
motor
main body
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB2010699.3A
Other versions
GB202010699D0 (en
Inventor
Mehta Arjun
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Edge Mobility Ltd
Original Assignee
Edge Mobility Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Edge Mobility Ltd filed Critical Edge Mobility Ltd
Priority to GB2010699.3A priority Critical patent/GB2599616A/en
Publication of GB202010699D0 publication Critical patent/GB202010699D0/en
Publication of GB2599616A publication Critical patent/GB2599616A/en
Withdrawn legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K5/00Casings; Enclosures; Supports
    • H02K5/04Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/20Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
    • H02K5/203Casings 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
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K5/00Casings; Enclosures; Supports
    • H02K5/04Casings or enclosures characterised by the shape, form or construction thereof
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K5/00Casings; Enclosures; Supports
    • H02K5/04Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/18Casings or enclosures characterised by the shape, form or construction thereof with ribs or fins for improving heat transfer
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K5/00Casings; Enclosures; Supports
    • H02K5/04Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/20Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K9/00Arrangements for cooling or ventilating
    • H02K9/19Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
    • H02K9/197Arrangements 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
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60LPROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2200/00Type of vehicles
    • B60L2200/12Bikes
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/64Electric machine technologies in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Motor Or Generator Cooling System (AREA)

Abstract

A motor 300 comprising a housing, which comprises a main body 400 and a cooling block 410, where the motor comprises a stator and a rotor contained within the main body. A coolant liquid is contained within the housing and is in thermal communication with the stator and/or the rotor. The motor also comprises a pump 305 having a liquid inlet 401a and a liquid outlet 401b, where the pump is fitted to the housing and promotes flow of the coolant liquid between the main body and the cooling block, with there being no separate pipes communicating the pump with the housing. The pump may be surface mounted having a mounting flange and a pump body attached to the mounting flange with a housing liquid outlet aperture may extend through the wall, and a housing liquid inlet aperture extending through the wall, where the flange is attached to the exterior of the housing wall so that the outlet aperture is aligned with the pump inlet and the inlet aperture is aligned with the pump outlet. Sealed channels may also provide a flow path for the liquid into the cooling block where the block may also be in thermal communication with the external environment. A reservoir may accommodate expansion and contraction of the liquid due to temperature fluctuations. The cooling block may form a structural component of an electric vehicle.

Description

LIQUID COOLED ELECTRIC MOTOR TECHNICAL FIELD
This invention relates to motors and vehicles with motors and methods of cooling motors and methods of making vehicles comprising motors.
BACKGROUND
Battery powered vehicles, driven by electric motors, are a large field of research, development, and commercialisation now. Electric motors, such as those used in transportation solutions, generate waste heat when in use. it is known to want to keep the temperature of the motor within a certain range to maximise performance, longevity, and safety.
Various cooling solutions have been posited previously. In CN102468704A, shown in Figure 1, a housing 4 for a motor, which sits on a base 5, is provided. Fluid filled copper tubes 3 extend outwards from one end of the housing 4 and arc connected into a net-shaped radiator with fins 2. When the motor is used, the heat generated by the motor is transferred to the radiator through the thermally conductive copper tubes 3 and fluid contained within. A fan 1 is also provided to further enhance cooling. Tubes may also be embedded into a stator of the motor itself, such as in US6819016B2 and CN109980804A. Figure 2 shows the system of CN109980804A. Tubes 51, 52 for carrying liquid coolant are located at ends of stator windings 24, the stator windings 24 being wrapped around a stator core 23. JPH10327558A provides a similar solution, having tubes embedded between the stator coils for carrying liquid coolant.
In such systems, the liquid coolant, once it has extracted heat from inside the electric motor, is then directed into a heat exchange system external to the electric motor, typically comprising an external pump, a radiator, external tubes, and/or a reservoir.
STATEMENT OF INVENTION
According to an aspect of the invention there is provided a motor. The motor comprises a housing. The housing comprises a main body and a cooling block. The motor further comprises a stator and a rotor contained within the main body. The motor further comprises a coolant liquid contained within the housing and in thermal communication with the stator and/or the rotor. The motor further comprises a pump, which has a pump liquid inlet and a pump liquid outlet. The pump is fitted to the housing and configured to promote flow of the coolant liquid between the main body and the cooling block. There are no separate pipes communicating the pump with the housing.
Not using pipes or other external cooling apparatus provides a smaller package size and reduced part count over motors and their cooling systems found in the prior art.
The likelihood of leaks and other failure modes are also reduced over prior art systems. This is particularly the case for motors used in vehicles, and even more so in vehicles such as motorcycles where the motor and cooling apparatuses are exposed. Vibrations associated with driving and riding can damage the sealing of connections and impacts to the vehicle can damage the exposed apparatuses. Having a motor with a reduced number of exposed apparatuses, as well as connections, therefore reduces the chances of damage and failures, as well as their associated costs, over conventional motors.
The pump may be a surface mounted pump having a mounting flange and a pump body attached to the mounting flange. The housing may have a housing wall and a housing liquid outlet aperture extending through the housing wall, and a housing liquid inlet aperture extending through the housing wall. The mounting flange may be attached to the exterior of the housing wall so that the housing liquid outlet aperture is aligned with and communicates with the pump liquid inlet and so that the housing liquid inlet aperture is aligned with and communicates with the pump liquid outlet. The pump liquid inlet and outlet may be provided in a face of the mounting flange, abutting a surface of the housing.
Directly mounting the pump to the housing provides a direct fluid communication. Sealingly connecting the pump ensures a robust mechanical connection, with reduced failure risks as compared to connections made using hoses and pipes.
The pump may alternatively be an internally mounted pump such that the pump is contained within the housing. Internally mounting the pump further protects the connections over externally mounting it, as the pump is protected from external impacts and damage. The pump may be a surface mounted pump having a mounting flange and a pump body attached to the mounting flange. The housing may have an internal wall and a housing liquid outlet aperture extending through the internal wall, and a housing liquid inlet aperture extending through the internal wall. The mounting flange may be attached to the internal wall of the housing so that the pump is contained within the housing and so that the housing liquid outlet aperture is aligned with and communicates with the pump liquid inlet and so that the housing liquid inlet aperture is aligned with and communicates with the pump liquid outlet.
The pump may be orientated in use at an angle such that air will naturally rise and escape from the pump through its outlet and/or its inlet, to minimise the likelihood of an air pocket accumulating inside the pump.
The orientation may be provided through the mounting position of the motor when installed in a vehicle. In other words, the pump may not necessarily be inclined when the motor has not been installed, but the orientation of the motor when installed results in an inclined pump. The orientation may be provided by attaching the pump to an inclined wall of the housing of the motor.
The housing may comprise an internal construction. The internal construction may be configured to direct coolant liquid flow into internal channels and/or keep coolant liquid flow coming from the pump liquid outlet separated from coolant liquid flow going to the pump liquid inlet.
The internal construction may comprise internal walls and/or formations of the housing. Using the internal construction of the housing in this manner reduces part count. It also reduces manufacturing steps, as the internal construction can be formed during a manufacturing step, such as casting or additive manufacturing, as opposed to through the extra step of inserting ducting or similar.
According to another aspect of the invention there is provided a motor. The motor comprises a housing. The housing comprises a main body and a cooling block. The motor further comprises a stator and a rotor contained within the main body. The motor further comprises a coolant liquid contained within the housing and in thermal communication with the stator and/or the rotor. The motor further comprises a pump, configured to provide flow of the coolant liquid within the housing. The motor further comprises sealed channels configured to provide a flow path for the coolant liquid. When the motor is in use, the sealed channels direct the coolant liquid from within the main body, proximal to the stator and/or the rotor, and into the cooling block and across one or more internal surfaces of the cooling block. An external surface of the cooling block is in thermal communication with an external environment, to provide a thermal communication pathway from the stator and/or the rotor to the external environment.
The motor therefore directly exchanges heat between the coolant liquid and the environment, replacing the need for an external radiator and a high-pressure drop coolant circuit as used in prior art systems. This further allows the use of a smaller pump, providing packaging and cost benefits.
The main body and the cooling block may comprise respective and complimentary fitting and/or locating means and wherein the fitting and/or locating means provide fluid pathways between the cooling block and the main body.
An internal construction of the cooling block may form the sealed channels at least in part.
The cooling block may comprise a main cooling block segment and a lid. The scaled channels may be formed, at least in part by sealingly attaching the lid to the main cooling block segment.
The internal construction of the cooling block may further comprise ribs and/or protrusions positioned within the sealed channels to promote heat transfer from the coolant liquid to the internal surfaces of the cooling block. Fins, vanes, projections and/or other formations may alternatively or additionally be provided on the external surface of the cooling block, for example on the external surface of the lid.
Using the internal construction of the cooling block in this manner reduces part count. It also reduces manufacturing steps, as the internal construction can be formed during a manufacturing step, such as casting or additive manufacturing, as opposed to the extra step of inserting ducting or similar. The addition of ribs and/or protrusions also increases the surface area of the coolant block that is in contact with the coolant liquid, and therefore increases the rate of heat transfer.
According to another aspect of the invention there is provided a motor. The motor comprises a housing and a stator and a rotor contained within the housing. The motor further comprises a coolant liquid contained within the housing and in thermal communication with the stator. The motor further comprises a reservoir contained within the housing and configured to accommodate expansion and contraction of the coolant liquid due to temperature fluctuations when the motor is in usc.
A volume of air may be provided in the reservoir to accommodate expansion and contraction of the coolant liquid when the motor is in use.
The volume of air provided may be dependent upon a volume change in the coolant liquid between an ambient temperature and a maximum operating temperature of the motor.
A pressure relief vent or valve may be provided in a top surface of the housing to provide a means for the air in the reservoir to leave or enter, to accommodate expansion and contraction of the coolant liquid when the motor is in use.
The pressure relief vent or valve may contain a semi-permeable membrane that allows the passage of air but restricts the passage of liquids, in particular the coolant liquid.
The semi-permeable membrane may be adapted to rupture or separate from the pressure relief vent or valve to allow the coolant liquid to escape from the motor in the event that the pressure of the coolant liquid gets too high.
According to another aspect of the invention there is provided a motor. The motor comprises a housing. The housing comprises a main body and a cooling block. The motor further comprises a stator and a rotor contained within the main body. The motor further comprises a coolant fluid contained within the housing and in thermal communication with the stator and/or the rotor. The motor further comprises a means for circulating the coolant fluid between the main body and the cooling block. The cooling block is a structural component of a vehicle.
The main body and the cooling block may comprise respective and complimentary fitting and/or locating means. The fitting and/or locating means may provide fluid pathways between the cooling block and the main body.
The structural component may be a structural component of a motorcycle such as a chassis component or a swing arm component.
Using a structural component of the vehicle as the cooling block can provide a larger surface area than using an end face of the motor. The part count is also reduced as a single component can be supplied whereas two would otherwise be required. As the cooling block is preferably made from aluminium it has good lightweight and structural properties that make it suitable for providing a structural role within the vehicle.
According to another aspect of the invention there is provided a motor comprising the features of at least two of, or three of, or preferably all of, the preceding aspects.
Similarly, any of the permutations of the motor described above and below may be combined in any combination in a single motor.
The housing may comprise heat transfer fins, vanes, projections and/or other formations on an external surface to exchange heat with the external environment. The external surface may be an axial end surface of the motor.
According to another aspect of the invention there is provided a small electrically powered vehicle, such as a scooter or motorcycle, having a motor in accordance with any of the preceding aspects. The motor comprises air cooling fins, vanes, projections and/or other formations on an external surface of the housing aligned generally from the front to the back of the vehicle.
According to another aspect of the invention there is provided a method of cooling a motor using a coolant liquid in thermal communication with a stator and/or a rotor of the motor and using a surface mounted pump mounted directly onto the exterior surface of a coolant-retaining housing to pump coolant liquid from a cooling block of the motor into a main body of the motor causing it to come into thermal communication with the stator and/or the rotor, and then back into the cooling Hock where it is channelled across internal walls of the cooling block, thereby transferring heat between the stator and/or the rotor and the housing without passing through pipework external to the motor.
According to another aspect of the invention there is provided a method of manufacturing a small electrically powered vehicle. The method comprises using a cooling block as a structural component of the vehicle, attaching a main body of a motor to the cooling block, the main body containing a stator and a rotor, such that the main body and the cooling block are in fluid communication, and providing a coolant liquid within the cooling block, the coolant liquid configured to provide a thermal pathway from the stator to an external environment of the vehicle when in use.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings of which: Figure 1 shows a prior art cooled electric motor housing; Figure 2 shows a prior art cooled electric motor stator; Figure 3 shows schematically a liquid cooled electric motor; Figure 4A shows schematically a main body of a liquid cooled electric motor; Figure 4B shows schematically a cooling block of a liquid cooled electric motor; Figure 5A shows schematically a pump for use in the motor of Figure 3; Figure 5B shows schematically a cross sectional view of the pump of Figure 5A; Figure 5C shows schematically a portion of a housing of the motor of Figure 3; Figure 5D shows schematically a cross section view of the pump of Figure 5 and a portion of the motor of Figure 3; Figure 6 shows schematically a cross section view of the cooling block of Figure 4B; Figure 7 shows schematically a further cross section view of the cooling block of Figure 4B; Figure 8 shows schematically the motor of Figure 3 installed in a vehicle; Figure 9A shows schematically the main body of Figure 4A being assembled with a vehicle component; Figure 9B shows schematically the main body of Figure 4A being assembled with another vehicle component; Figure 10 shows a method of manufacturing a vehicle comprising a motor; and Figure II shows a method for cooling an electric motor.
DETAILED DESCRIPTION
A liquid cooled motor 300 is shown in Figure 3. For ease of description the motor 300 is described by reference to a top 301, bottom 302, left side 303 and right side 304. These labels are with respect to a preferred orientation of the motor 300 when in-use. However, the motor 300 may be orientated differently; for example in rotation around a vertical axis (that is an axis running from the bottom to the top) such that the front and back may be reversed or the front and back may become the left and right. The motor 300 has a liquid cooling system. The motor comprises a housing. The housing is formed from two major components, a main body 400, and a cooling block 410. The housing contains active components. The active components are a stator and a rotor (not shown). A plurality of further components are mounted on to the housing.
The main body 400 makes up the majority of the housing of the motor 300. The main body 400 comprises a plurality of sealingly connected housing components. A centre section 312 provides a main volume of the main body 400. The centre section 312 is capped at one end with a first end plate 311 and at another end with a second end plate 313.
The cooling block 410 comprises a plurality of sealingly connected cooling block components. A main cooling block segment 314 provides a main volume for the cooling block 410. A cooling block lid 315 is scalingly connected to the main cooling block segment 314 to close the volume within the main cooling block segment 314. The cooling block lid 315 is fitted to the main cooling block segment 314 at an end distal from the main body 400. A plurality of external fins 306 are provided on the cooling block. The fins 306 are positioned such that, when the motor 300 is installed in a vehicle, they run substantially parallel to the main direction of air flow when the vehicle is in motion. The fins are therefore situated on an axial end of the motor 300. The fins extend transversely to an axis of the motor 300.
The further components that are mounted on to one or both of the main body 400 and the cooling block 410 comprise a pressure relief vent 320 (which may be a pressure relief valve) and a pump 305. Specifically, the pressure relief vent 320 is mounted to the cooling block 410. Specifically the pump 305 is mounted to the cooling block 410. The pump 305 is positioned below the pressure relief vent 320 when the motor 300 is installed in a vehicle. The pump is inclined with respect to a ground plane when the motor 300 is installed in a vehicle. The incline of the pump provides a means by which any air that may accumulate in the pump during acceleration or tilting of the vehicle can naturally rise out and reduce the likelihood of dry pumping and associated possible damage to the pump.
The main body 400 is shown in more detail, with the cooling block 410 removed (or before being assembled with the cooling block), in Figure 4A. A plurality of liquid inlets 401a and outlets 401b are provided in a face of the main body. The inlets and outlets are connected to axial flow paths within the main body 400. The flow from the inlets 401a follows flow paths 405 into the main body. The flow to the outlets 401b follows flow paths 406 out of the main body 400. The flow paths 405, 406 form closed loops, allowing the coolant liquid to flow within the main body 400. Each inlet 401a and outlet 40lb has a sealing means 402 attached to it to prevent leakage of coolant liquid when the motor 300 is assembled. The scaling means comprise 0-rings 402 that are placed around male protrusions that form the inlets 401a and outlets 401b. Other sealing means may be implemented, such as a gasket. A plurality of bolt holes 404 are provided in the main body 400 to provide an attachment means for attaching the main body 400 to the cooling block 410.The cooling block 410 is shown in more detail, removed from (or pre-assembly to) the main body 400, in Figure 4B. A plurality of outlets 41! a and inlets 411 b are provided in a face of the cooling block 410 that interfaces with the main body 400. The outlets 411a of the cooling block 410 correspond to the inlets 401a of the main body 400. The inlets 411b of the cooling block 410 correspond to the outlets 401b of the main body 400. The respective inlets and outlets provide fluid communication between the main body and the cooling block 410. The respective inlets and outlets also provide a locating and fitting means, using a peg and hole connection. In this example the male inlets and outlets are provided on the main body 400 and the female inlets and outlets arc provided on the cooling block 410, this arrangement may be reversed in other examples, with male parts on the cooling block 410 and female parts on the main body 400. Bolt holes 414 for fixing the cooling block 410 to the main body 400 are provided. The bolt holes 414 correspond to the bolts holes 404 of the main body. The cooling block is made from a lightweight material with good heat conductivity. Aluminium is an example of a suitable material. The cooling block is formed by casting. Internal channels and ribs and external fins and interfaces for fitting the pump and pressure relief vent are formed in the cooling block as discussed in further detail below.
One of the pumps 305 is shown in more detail in Figure 5A. The pump 305 is a small pump which comprises a manifold 501 having a flat interface surface. The manifold provides a means by which the pump can be mounted directly into a flat surface of the main body. This removes extra components, such as tubing or clamps, which may be required for pumps not directly mounted to the main body. The manifold has a sealed interface with a wall of the housing to prevent leaking. The sealed interface is provided with a seal 502 provided on the flat surface of the manifold, which is located between the manifold and the housing when the pump 305 is installed. The pump 305 comprises an inlet 503, through which liquid can enter the pump, and an outlet 504, through which a liquid can be ejected from the pump.
The pump 305 is a centrifugal pump. A sectional view of an example of a suitable pump is shown in Figure 5B. An impeller 506 is located within the body 505 of the pump 305 and is driven by a motor 507 to provide the pumping action. Liquid is drawn in through the inlet 503 through the action of the impeller 506, which then ejects the coolant liquid towards and then out of the outlet 504. Other pump arrangements may also be used that provide an inlet and outlet in the same surface.
The coolant liquid flow 517 through the pump 305 is indicated by the arrows in the figure.
A region of the motor 300 is shown in Figure 5C, with the pump 305 removed, providing further detail with regards to an installation location of the pump 305. An inlet hole 512 and an outlet hole 513 are provided in a flat surface of a wall of the cooling block 410. The inlet hole 512 corresponds to thc outlet 504 of the pump. The outlet hole 513 corresponds to the inlet 503 of the pump.
The installation of the pump is shown in a blown apart and partially sectional view in Figure 5D. The inlet hole 512 and outlet hole 513 of the cooling block 410 are separated by the internal construction 514 and walls of the cooling block 410. This separation allows for the circulation of coolant liquid within the cooling block, as the inlet and outlet are physically separated, the coolant liquid is prevented from simply circulating proximal to the pump. Instead the coolant liquid flow 517 is directed from the inlet hole 512 in the cooling block wall to further internal cooling channels through a first channel 515, until it returns to the outlet hole 513 in the main body wall via a second channel 516.
In this way the pump can be surface mounted directly onto the surface of the cooling block. This provides a single sealed interface which in turn avoids the need for any tubes/fittings reducing part count, assembly costs and the risk of a leakage. The motor 300 uses the cooling block's internal construction in order to keep the inlet and outlet flows separated and direct these flows to internal cooling channels within the cooling block.
Various means for mounting the pump 305 to the cooling block 410 can be used. For example, the pump manifold 501 can be welded to the cooling block 410 and/or a threaded hole or recess can be provided in the cooling block 410 to correspond to a bolt associated with the pump 305. Any means that ensure a sealed fit between the cooling block 410 and the pump 305 may be used.
In some examples of the motor the pump 305 may instead be internally mounted. For example, the pump 305 can be positioned within a recess within the cooling block 410. The wall to which the pump attaches is therefore an internal wall.
The coolant liquid flow 517 within the cooling block 410 is shown in more detail in Figure 6. The cooling block lid 315 has been removed from the main cooling block segment 314 in order to show the channels 515, 516 formed within the cooling block 410. In this example the channels are enclosed by scalingly connecting the cooling block lid 315 to the main cooling block segment 314. The cooling block lid 315 has channels that correspond to the channels of the cooling block segment 314. Both the channels of the cooling block segment 314 and the cooling block lid are semi-circular in cross section, such that a channel of circular cross section is formed when the lid and the segment are joined to form the cooling block 410. In other examples the channels may be formed internally within the main cooling block segment 314. For example, the cooling block may be manufactured using investment casting or additive manufacturing in order to create the internal structures to form the channels.
The outlets 411a and inlets 411b are shown that direct coolant liquid into and out of the main body 400 respectively. The outlets 411a are connected to the first channel 5[5 and the inlets 411b are connected to the second channel 516. The channels follow curved paths within the cooling block in order to increase the length of the channels within the cooling block 410 over linking to the pump via more direct routes. This increase in length provides the coolant liquid with a greater time and distance over which it is within the cooling block, and can therefore transfer more heat to the cooling block and to the external environment in order to dissipate more heat from the motor.
A reservoir 601 is provided that is in fluid communication with the channels. More detail of this arrangement is shown in Figure 7. The reservoir is connected to the pressure relief vent 320. The reservoir is positioned above the attachment point of the pump 305 such that any air 701 within the system naturally rises into the reservoir. The reservoir is the topmost fluid containing feature within the motor, such that any air naturally accumulates there. The pressure relief vent comprises a semi-permeable membrane 705 which allows the passage of air to and from the reservoir from and to an external environment but prevents the passage of coolant liquid 702. When the coolant liquid 702 expands due to an increase in the temperature of the motor, air is forced out of the reservoir through the pressure relief vent 320, helping to maintain the internal pressure. As the motor cools and the coolant liquid 702 contracts, air is drawn back into the reservoir through the pressure relief vent 320. The pressure within the cooling system is highest proximal to the pump outlet and therefore in the outlet channels within the cooling block before the coolant liquid 702 enters the main body 400. The pressure within the cooling system is lowest proximal to the pump inlet and therefore in the inlet channels within the cooling block, after the coolant liquid 702 has exited the main body 400. The reservoir 601 is connected to the lower pressure side of the system. The volume of air provided is based on a change in volume of the coolant liquid over the range of operating temperatures the motor may operate at. The volume of air provided, at an ambient temperature, is therefore equal to or greater than a change in volume of the coolant liquid from ambient temperature to a maximum operating temperature. As the liquid volume increases with temperature it expands to fill the reservoir, pushing the air contained within the reservoir out into the external environment. As the coolant liquid cools it retracts from the reservoir and air is drawn back in through the pressure relief vent 320.
The semi-permeable membrane 705 in the pressure relief vent 320 is adapted so that it will rupture in the event that the pressure of the coolant liquid inside the motor gets too high, for example if the coolant liquid overheats to a temperature above the maximum operating temperature. The pressure at which the semi-permeable membrane will rupture is between 0.2 bar gauge and 9 bar gauge, preferably between 2 bar gauge and 3 bar gauge.
At ambient temperature and at atmospheric pressure the volume of air is between 3% and 15% of the volume of coolant liquid. Preferably the volume of air is between 5% and 8% of the volume of coolant liquid. Still preferably the volume of air is about 7% of the volume of coolant liquid. In a specific example the volume of coolant liquid is 0.22 litres and the volume of air is 0.015 litres at ambient temperature and atmospheric pressure. As the operating temperature of the motor increases the temperature of the coolant liquid increases and the volume of the liquid also increases slightly. This increase in liquid volume pushes the air out through the vent and the volume of liquid replaces the volume of air. The volume of liquid at I00°C is approximately 0.235 litres, which is the total volume of the cooling system of the motor, and the volume of air is approximately 0 litres. The coolant liquid is a water/glycol mix in this and other examples. In some examples the coolant liquid is an electrically non-conductive liquid. The volume of air is adjusted in dependence on a predicted volume change in the coolant liquid over an operating temperature range of the motor.
Bolt holes 602 are provided for attaching the cooling block lid 315 to the main cooling block segment 314. The bolt holes 602 for attaching the cooling block lid 315 to the main cooling block segment 314 may be the same holes as the bolt holes 414 for attaching the cooling block 410 to the main body 400.
The motor 300 is typically for use in a powertrain system in a vehicle to provide propulsion. Figure 8 shows the motor 300 installed in a two-wheeled vehicle such as a motorcycle 800. The majority of the motorcycle components have been removed for clarity, the wheels and front forks left to show an orientation of the motorcycle. The motor 300 is installed such that the pump 305 is inclined relative to a ground plane upon which the vehicle travels when in use, such that the outlet of the pump is above the main body of the pump, this prevents air from accumulating within the pump. The motor 300 is installed so that the fins 306 run parallel to a direction of travel of the motorcycle, such that the air flow 805 over the fins is predominantly along their length when the vehicle is in forward motion.
Various design modifications and configurations of the motor may be implemented to the motor 300 in order to integrate it with a vehicle. Figures 10A and 10B provide examples in which the cooling block has been integrated into a structural component of the vehicle. In Figure 9A the cooling block is integrated into a motorcycle chassis 910 and in Figure 9B the cooling block is integrated into a motorcycle swing arm 920. Installing the motor 300 into a vehicle 800 therefore comprises sealingly attaching the main body 400 to the pre-installed cooling block 410.
Providing the cooling block as part of the structure of the vehicle rather than as part of the motor offers various benefits. The overall component cost, assembly time and mass is reduced over supplying two separate components. The surface area of the cooling block can also be increased, making use of the larger area provided by the structural components over a conventional end face of a motor. This increased surface area provides increased heat dispersion.
During vehicle assembly, the motor is sealingly connected to the integrated cooling block. Once installed an appropriate volume of coolant liquid is filled into the system. The volume of coolant liquid is slightly less than the cooling system volume to provide for air within the reservoir. The pump and pressure relief vent are then sealingly connected to the cooling block to seal the system. It will be appreciated that this order may be modified. For example, the pump may be connected prior to filing and coolant liquid may be supplied using an aperture into which the pressure relief vent is to be inserted.
An example of method steps for assembling the motor into the vehicle is shown in Figure 10. The cooling block is provided 1001 and used as a structural component of the vehicle. The structural component might be a chassis or other sprung mass component, or it may instead be an unsprung mass component such as the swing arm. Once the structural components of the motorcycle are assembled, including the cooling block, the main body is sealingly connected 1002 to the cooling block.
Finally, the coolant liquid is provided 1003 into the completed housing formed by the cooling block and the main body.
A method of cooling the motor when it is in use is shown in Figure 11. The coolant liquid is pumped 2001 through the cooling block and into the main body. Once in the main body the cooling liquid comes into thermal communication 2002 with the stator. At this point heat is transferred from the stator, and the surrounding components, such as the rotor, to the coolant liquid. The coolant liquid then returns 2003 to the cooling block form the main body. Once back in the cooling block the coolant liquid comes into thermal communication 2004 with an internal wall of the cooling block. The heat is transferred from the cooling liquid to the internal surface of the cooling block 2004 and then out from an external surface of the cooling block to the external environment 2005. The transfer is promoted by increased surface area provided by fins, ribs, projections and/or other formations inside and/or outside of the cooling block. Heat transfer is further enhanced when the motor is mounted in a vehicle and the vehicle is in motion, as air passes over the external fins, providing forced convection.
Various modifications can be made to the examples and embodiments described above without departing from the scope of the appended claims. For example, where parts fit together in a male/female relationship it is also envisaged that the relationship is reversed. Features of the examples and embodiments may be exchanged, combined, omitted or adapted. The teaching of the specification should be taken as a whole with no limitation placed on the scope of the appended claims by reference to the included description and drawings.

Claims (27)

  1. CLAIMSA motor comprising: a housing, the housing comprising a main body and a cooling block; a stator and a rotor contained within the main body; a coolant liquid contained within the housing and in thermal communication with the stator and/or the rotor; a pump having a pump liquid inlet and a pump liquid outlet, wherein the pump is fitted to the housing and configured to promote flow of the coolant liquid between the main body and the cooling block, there being no separate pipes communicating the pump with the housing.
  2. A motor according to claim 1 wherein: the pump is a surface mounted pump having a mounting flange and a pump body attached to the mounting flange; the housing has a housing wall and a housing liquid outlet aperture extending through the housing wall, and a housing liquid inlet aperture extending through the housing wall; and wherein the mounting flange is attached to the exterior of the housing wall so that the housing liquid outlet aperture is aligned with and communicates with the pump liquid inlet and so that the housing liquid inlet aperture is aligned with and communicates with the pump liquid outlet.
  3. 3 A motor according to claim 2 wherein the pump liquid inlet and outlet are provided in a face of the mounting flange, abutting a surface of the housing.
  4. 4. A motor according to claim 1 wherein the pump is an internally mounted pump such that the pump is contained within the housing.
  5. A motor according to claim 4 wherein: the pump is a surface mounted pump having a mounting flange and a pump body attached to the mounting flange; the housing has an internal wall and a housing liquid outlet aperture extending through the internal wall, and a housing liquid inlet aperture extending through the internal wall; and wherein the mounting flange is attached to the internal wall of the housing so that the pump is contained within the housing and so that the housing liquid outlet aperture is aligned with and communicates with the pump liquid inlet and so that the housing liquid inlet aperture is aligned with and communicates with the pump liquid outlet.
  6. 6. A motor according to any preceding claim wherein the pump is orientated in use at an angle such that air will naturally rise and escape from the pump through its outlet and/or its inlet, to minimise the likelihood of an air pocket accumulating inside the pump.
  7. 7. A motor according to any preceding claim, wherein the housing comprises an internal construction and wherein the internal construction is configured to direct coolant liquid flow into internal channels and/or keep coolant liquid flow coming from the pump liquid outlet separated from coolant liquid flow going to the pump liquid inlet.
  8. 8. A motor according to claim 7, wherein the internal construction comprises internal walls, and/or formations of the housing.
  9. A motor comprising: a housing, wherein the housing comprises a main body and a cooling block; a stator and a rotor contained within the main body; a coolant liquid contained within the housing and in thermal communication with the stator and/or the rotor; a pump, configured to provide flow of the coolant liquid within the housing; sealed channels configured to provide a flow path for the coolant liquid wherein, when in use, the sealed channels direct the coolant liquid from within the main body, proximal to the stator and/or the rotor, and into the cooling block and across one or more internal surfaces of the cooling block, wherein an external surface of the cooling block is in thermal communication with an external environment, to provide a thermal communication pathway from the stator and/or the rotor to the external environment.
  10. 10. A motor according to claim 9 wherein the main body and the cooling block comprise respective and complimentary fitting and/or locating means and wherein the fitting and/or locating means provide fluid pathways between the cooling block and the main body.
  11. I I. A motor according to claim 9 or claim 10, wherein an internal construction of the cooling block forms the sealed channels at least in part.
  12. 12. A motor according to claim 11, wherein the cooling block comprises a main cooling block segment and a lid, and wherein the sealed channels arc formed, at least in part by sealingly attaching the lid to the main cooling block segment.
  13. 13. A motor according to claim 11 or claim 12 wherein the internal construction of the cooling block comprises ribs and/or protrusions positioned within the sealed channels to promote heat transfer from the coolant liquid to the internal surfaces of the cooling block.
  14. 14. A motor comprising: a housing; a stator and a rotor contained within the housing; a coolant liquid contained within the housing and in thermal communication with the stator and/or the rotor: a reservoir contained within the housing and configured to accommodate expansion and contraction of the coolant liquid due to temperature fluctuations when the motor is in use
  15. 15. A motor according to claim 14, wherein a volume of air is provided in the reservoir to accommodate expansion and contraction of the coolant liquid when the motor is in use.
  16. 16. A motor according claim 15, wherein the volume of air provided is dependent upon a volume change in the coolant liquid between an ambient temperature and a maximum operating temperature of the motor.
  17. 17. A motor according to claim 15 or claim 16, wherein a pressure relief vent or valve is provided in a top surface of the housing to provide a means for the air in the reservoir to leave or enter, to accommodate expansion and contraction of the coolant liquid when the motor is in use.
  18. 18. A motor according to claim 17, wherein the pressure relief vent or valve contains a semi-permeable membrane that restricts the passage of liquids, in particular the coolant liquid.
  19. 19. A motor according to claim 18, wherein the semi-permeable membrane is adapted to rupture or separate from the pressure relief vent or valve to allow the coolant liquid to escape from the motor in the event that the pressure of the coolant liquid gets too high.
  20. 20. A motor comprising: a housing, wherein the housing comprises a main body and a cooling block; a stator and a rotor contained within the main body; a coolant fluid contained within the housing and in thermal communication with the stator and/or the rotor; a means for circulating the coolant fluid between the main body and the cooling block; wherein the cooling block is a structural component of a vehicle.
  21. 21. A motor according to claim 20 wherein the main body and the cooling block comprise respective and complimentary fitting and/or locating means and wherein the fitting and/or locating means provide fluid pathways between the cooling block and the main body.
  22. 22. A motor according to claim 20 or claim 21, wherein the structural component is a structural component of a motorcycle, such as a chassis component or a swing arm 15 component.
  23. 23. A motor comprising the features of at least two of, and preferably any two, three, or all four of: a. claim 1, or any of its dependent claims; b. claim 9, or any of its dependent claims; c. claim 14, or any of its dependent claims and c. claim 20, or any of its dependent claims.
  24. 24. A motor according to any preceding claim wherein the housing comprises heat transfer fins, vanes, projections and/or other formations on an external surface to exchange heat with the external environment, and preferably wherein the external surface is an axial end surface of the motor.
  25. 25. A small electrically powered vehicle, such as a scooter or motorcycle, having a motor in accordance with any preceding claim, wherein the motor comprises air cooling fins, vanes, projections and/or other formations on an external surface of the housing aligned generally from the front to the back of the vehicle.
  26. 26. A method of cooling a motor using a coolant liquid in thermal communication with a stator and/or a rotor of the motor and using a surface moimted pump mounted directly onto an exterior surface of a coolant-retaining housing to pump coolant liquid from a cooling block of the motor into a main body of the motor causing it to come into thermal communication with the stator and/or the rotor, and then back into the cooling Hock where it is channelled across an internal surface of the cooling block, thereby transferring heat from the stator and/or the rotor to the surfaces of the cooling block without passing through pipework external to the motor.
  27. 27. A method of manufacturing a small electrically powered vehicle, the method comprising: using a cooling block as a structural component of the vehicle; attaching a main body of a motor to the cooling block, the main body containing a stator and a rotor, such that the main body and the cooling block are in fluid communication: and providing a coolant liquid within the cooling block and the main body, the coolant liquid configured to provide a thermal pathway from the stator and/or the rotor to an external environment of the vehicle when in use.
GB2010699.3A 2020-07-10 2020-07-10 Liquid cooled electric motor Withdrawn GB2599616A (en)

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Publication number Priority date Publication date Assignee Title
CN118659586A (en) * 2022-02-11 2024-09-17 华为数字能源技术有限公司 Power assembly and vehicle

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04185263A (en) * 1990-11-20 1992-07-02 Aisin Aw Co Ltd Cooling apparatus of wheel motor
US20080067882A1 (en) * 2006-09-15 2008-03-20 Toyota Jidosha Kabushiki Kaisha Motor
US20100295391A1 (en) * 2009-05-19 2010-11-25 Ford Global Technologies, Llc Cooling System And Method For An Electric Motor
US20110175467A1 (en) * 2010-01-19 2011-07-21 Brian Belton Coolant system for electric motorcycle
WO2019131454A1 (en) * 2017-12-28 2019-07-04 日本電産株式会社 Motor unit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04185263A (en) * 1990-11-20 1992-07-02 Aisin Aw Co Ltd Cooling apparatus of wheel motor
US20080067882A1 (en) * 2006-09-15 2008-03-20 Toyota Jidosha Kabushiki Kaisha Motor
US20100295391A1 (en) * 2009-05-19 2010-11-25 Ford Global Technologies, Llc Cooling System And Method For An Electric Motor
US20110175467A1 (en) * 2010-01-19 2011-07-21 Brian Belton Coolant system for electric motorcycle
WO2019131454A1 (en) * 2017-12-28 2019-07-04 日本電産株式会社 Motor unit

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