DESC:TECHNICAL FIELD
[001] This disclosure relates generally to heat exchangers, and more particularly to a cooling system for an electric motor of electric vehicles.

BACKGROUND
[002] Electric vehicles use a single reduction gear box coupled with an electric motor that drives the vehicle in forward as well as reverse direction at a required speed and torque. The electric motor can be either a three phase induction motor, a brush less Direct Current (DC) motor, or a synchronous motor. However, all the electric motor face a common problem of power loss due to heating during operation of the vehicle. The electric motor is a closed device, and as such works in accordance with how it was built or the kind it belongs to.
[003] The electric motor generates heat with fluctuation in load current. In this jerking condition, the electric motor requires current that could meet the required torque. However, the conversion of electrical energy into mechanical energy is only as efficient as the construction of the motor. This dependency needs to be compensated with an external cooling system that has to be installed adjacent to the electric motor. Further, the cooling system device should envelop the electric motor so as order to reduce its temperature, to thereby improve the performance and reliability of the electric motor.

SUMMARY
[004] In an embodiment, a cooling system for an electric motor is disclosed. The cooling system may include a fluid reservoir configured to receive therein and supply a coolant fluid. The fluid reservoir may be positioned on a top side of a housing of the electric motor. The fluid reservoir may define a bottom reservoir-surface in thermal contact with a housing-surface associated with the top side of the housing of the electric motor. The cooling system may further include a conduit fluidically coupled with the fluid reservoir and configured to circulate the coolant fluid therethrough. The conduit may envelop the housing of the electric motor. The conduit may further define a plurality of linear pathways extending along a longitudinal length of the housing of the electric motor and a plurality of bends. Each of the plurality of bends may be fluidically coupling a pair of adjacent linear pathways of the plurality of linear pathways. The plurality of bends may be positioned in proximity to extreme ends of the longitudinal length of the housing of the electric motor.
[005] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS
[006] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, explain the disclosed principles.
[007] FIG. 1 illustrates a schematic perspective view of a cooling system implemented on an electric motor, in accordance with some embodiments of the present disclosure.
[008] FIG. 2 illustrates a schematic perspective view of the cooling system, in accordance with some embodiments.
[009] FIG. 3 illustrates another schematic perspective view of the cooling system, in accordance with some embodiments.
[010] FIG. 4 illustrates a schematic diagram of the fluid reservoir showing the coolant fluid flow gradient therein, in accordance with some embodiments.
[011] FIG. 5 illustrates another schematic perspective view of the cooling system implemented on the electric motor, in accordance with some embodiments.

DETAILED DESCRIPTION
[012] Exemplary embodiments are described with reference to the accompanying drawings. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the spirit and scope of the disclosed embodiments. It is intended that the following detailed description be considered as exemplary only, with the true scope and spirit being indicated by the following claims. Additional illustrative embodiments are listed below.
[013] The present disclosure is about implementation of a coolant-based cooling system, especially for cooling an electric motor, for example, of an electric vehicle. The cooling system may be implemented via a heat extraction structure that may be positioned around the electric motor to extract heat generated by the electric motor for better performance of the electric motor.
[014] The heat extraction structure provided by the cooling system is such that primary supply of a coolant (for example, a liquid) initiates from a fluid reservoir. The fluid reservoir, for example, may be a box made from a material selected from one of Copper, Aluminum, and alloys thereof. The fluid reservoir may be positioned on top of the electric motor. This box may include walls, each having a thickness of 1 millimeter (mm) and overall dimensions of 200 mm X 400 mm X 20 mm. The fluid reservoir may further include an inlet and an outlet having a diameter of 10 mm. A conduit, for example, made from copper material, having a network of multiple bends may envelop the electric motor in a circular fashion. For example, the conduit may have a network of twelve bends. The coolant may travel through the conduit, i.e. the bends and linear lengths of the conduit, and therefore, around the electric motor to extract heat from all sides of the electric motor with maximum efficiency.
[015] Based on the simulation study, when a coolant with a temperature of 25 ?C and mass flow rate of 0.1 kilogram per second (kg/sec) is passed through the conduit, the outlet temperature is nearly 98 ?C. The simulation study was performed considering the motor temperature at 120 ?C which is a standard temperature of a three-phase alternating current (AC) induction motor at loading condition. The gain of the working fluid was nearly 73 ?C which depicts the successful functioning of the above cooling system. The more heat the working fluid extracts, more is its change in temperature. Further, a copper covering of the fluid domain of thickness 1 mm exhibits a similar behavior to the above constrained simulation where the temperature of the surface reaches near to the load temperature of 120 ?C. This is due to the high thermal conductivity of copper which is nearly 400 watt/mk.
[016] Referring to FIG. 1, a schematic perspective view 100 of a cooling system 100A implemented on an electric motor 100B is illustrated, in accordance with some embodiments of the present disclosure. In some embodiments, the cooling system 100A may be enveloped around the electric motor 100B. As can be seen in FIG. 1, the electric motor may typically have a cylindrical structure such that the heat is mostly accumulated along the side surface of the cylindrical structure. As such, in order to remove the heat generated, the cooling system 100A may be positioned around the side surface of the electric motor 100B, as shown in FIG. 1. A cooling fluid may circulate through the cooling system 100A that may absorb heat from the surface of the electric motor 100B.
[017] The electric motor 100B, as shown in FIG. 1, may be housed in a housing 104. In other words, the electric motor 100B may include the housing 104 acting as an external casing and an internal core (not shown in FIG. 1) of the electric motor 100B may be disposed within the housing 104. During the operation of the electric motor, heat generated by the electric motor 100B may be accumulated in the housing 104.
[018] In some embodiments, the cooling system 100A may include a fluid reservoir 102 configured to receive therein and supply a coolant fluid. For example, as shown in FIG. 1, the fluid reservoir 102 may be configured in a rectangular shape (i.e. a cuboidal profile) having a bottom reservoir-surface 102A, a top reservoir-surface 102B, and a plurality of side walls 102C. The top reservoir-surface 102B may be disposed opposite to the bottom reservoir-surface 102A. The plurality of side walls 102C may be defined between the bottom reservoir-surface 102A and the top reservoir-surface 102B. Further, as shown in FIG. 1, the fluid reservoir 102 may have four side walls 102C. In some embodiments, the fluid reservoir 102 may be made from a heat conductive material, and such from a metal or an alloy having high heat conductivity property. In one particular example, the fluid reservoir 102 may be made from Copper, or Aluminum, or an alloy.
[019] In some example embodiments, each of the bottom reservoir-surface 102A and the top reservoir-surface 102B may have measurements of 200 millimeters (mm) X 400 mm. Further, in some embodiments, thickness of the bottom reservoir-surface 102A, the top reservoir-surface 102B, and the plurality of side walls 102C may be 1 mm.
[020] The fluid reservoir 102 may be positioned on a top side of the housing 104 of the electric motor 100B. For example, the housing 104 may include a substantially planar housing-surface that may accommodate the positioning of the housing 104 over it. The bottom reservoir-surface 102A of the fluid reservoir 102 may be in thermal contact with the housing-surface associated with the top side of the housing 104 of the electric motor 100B. As will be appreciated, a flat planar configuration of the bottom reservoir-surface 102A and the housing-surface associated with the top side of the housing 104 may allow for an effective heat transfer therebetween via heat conduction.
[021] The cooling system 100A may further include a conduit 106 which may be fluidically coupled with the fluid reservoir 102. For example, as shown in FIG. 1, the conduit 106 may have a serpentine-like structure that may envelop the housing 104 of the electric motor 100B along a side surface 104A of the housing 104. The conduit 106 may be made from a heat-conductive and rigid material, such as a metal or an alloy. In one particular example, the conduit 106 may be made from Copper, or Aluminum, or an alloy. Further, in some embodiments, the conduit 106 may have a hollow circular cross-section profile. Further, in some example embodiments, the diameter of the conduit 106 may be 10 mm. The hollow profile of the conduit 106 may be configured to circulate the coolant fluid therethrough. The conduit 106 may be positioned in a way to envelop the housing 104 of the electric motor 101.
[022] The conduit 106 may be fluidically coupled with the fluid reservoir 102 via an inlet port 108 and an outlet port 110. Each of the inlet port 108 and the outlet port 110 may be configured in a circular cross-section similar to the circular cross-section profile of the conduit 106. For example, the diameter of each of the inlet port 108 and the outlet port 110 configured in the circular cross-section may be 10 millimeters (mm). Further, in some embodiments, the conduit 106 may welded with the fluid reservoir 102 i.e. at the inlet port 108 and the outlet port 110. In alternate embodiments, the conduit 106 may be formed as part of the fluid reservoir 102.
[023] In some embodiments, the inlet port 108 may be fluidically coupled with a coolant fluid supply (not shown in FIG. 1). Further, the outlet port 110 may be fluidically coupled with the conduit 106, via a first end of the conduit 106. In other words, the fluid reservoir 102 may receive the cooled coolant fluid from the coolant fluid supply via the inlet port 108. In some embodiments, the coolant fluid may be introduced into the fluid reservoir 102 at a temperature of 25 °C.
[024] The coolant fluid supply, for example, may be a radiator which may cause heat exchange between a heated coolant fluid and a cold medium (for example, atmospheric air) to thereby remove heat and cool down the coolant fluid. This cooled coolant fluid, upon being received in the fluid reservoir 102, may then exit the fluid reservoir 102 via the outlet port 110, to be circulated throughout the conduit 106. The coolant fluid during circulation may absorb heat from the electric motor 100B that may cause a temperature rise of the coolant fluid. The heated coolant fluid, upon circulation, may exit the conduit 106 via a second end of the conduit 106. For example, the heated coolant fluid may exit the conduit 106 at a temperature of around 98 °C. The conduit 106 is therefore configured to release the coolant fluid to the coolant fluid supply, via the second end of the conduit 106. The heated coolant fluid may then enter the coolant fluid supply, and the cycle may continue.
[025] In some embodiments, the coolant fluid may be circulated through the conduit 106 at a mass flow rate of 0.1 kilogram per second kg/sec. To this end, the coolant fluid may be circulated through the conduit 106 via a pump (not shown in FIG. 1). For example, the pump may be positioned between the coolant fluid supply and the fluid reservoir 102, and therefore, may cause the flow rate of 0.1 kg/sec of the coolant fluid mass. Alternatively, the pump may be positioned between the second end of the conduit 106 and the coolant fluid supply.
[026] The conduit 106 may define a plurality of linear pathways 106A extending along a longitudinal length of the housing 104 of the electric motor 100B. Further, the conduit 106 may define a plurality of bends 106B. Each of the plurality of bends 106B may be fluidically couple with a pair of adjacent linear pathways 106A of the plurality of linear pathways 106A. For example, as shown in FIG. 1, each of the plurality of bends 106B may be configured in a semi-circular shape.
[027] As will be understood, the serpentine structure of the conduit 106 may define the multiple linear pathways 106A extending along a longitudinal length of the housing 104 and the plurality of bends 106B. As shown in FIG. 1, the conduit 106 may define the plurality of linear pathways 106A extending along a longitudinal length of the housing 104 of the electric motor 100B. The plurality of bends 106B may be positioned in proximity to extreme ends of the longitudinal length of the housing 104 of the electric motor 100B. Further, the conduit 106 may define a plurality of bends 106B. Each of the plurality of bends 106B may be fluidically couple with a pair of adjacent linear pathways 106A of the plurality of linear pathways 106A. As will be understood, the serpentine structure of the conduit 106 may be implemented via the multiple linear pathways 106A extending along the longitudinal length of the housing 104 and the plurality of bends 106B. For example, in some embodiments, the conduit 106 may include define twelve bends 106B and a corresponding number of the linear pathways 106A. it should be noted that the number of bends 106B and the linear pathways 106A may differ based on the size of the housing 104 and the cross-section of the conduit 106.
[028] It should be noted that the plurality of bends 106B may be created by bending an elongated length of the conduit 106. Alternatively, the bends 106B may be manufactured separately and then coupled with plurality of linear pathways 106A to thereby create the serpentine structure of the conduit 106.
[029] Referring now to FIG. 2, a schematic perspective view of the cooling system 100A is illustrated, in accordance with some embodiments. As mentioned above, the cooling system 100A may include the fluid reservoir 102 configured to receive therein and supply a coolant fluid and the conduit 106 which may be fluidically coupled with the fluid reservoir 102. As shown in FIG. 2, the conduit 106 may have a serpentine-like structure that may envelop the housing (not shown in FIG. 2) of the electric motor. The conduit 106 may have a hollow circular cross-section profile that may allow to circulate the coolant fluid therethrough. The conduit 106 may be fluidically coupled with the fluid reservoir 102 via the inlet port 108 and the outlet port 110. Each of the inlet port 108 and the outlet port 110 may be configured in a circular cross-section similar to the circular cross-section profile of the conduit 106. The conduit 106 may be welded with the fluid reservoir 102 i.e. at the inlet port 108 and the outlet port 110, or may be formed as part of the fluid reservoir 102.
[030] The inlet port 108 may be fluidically coupled with a coolant fluid supply (not shown in FIG. 2) and the outlet port 110 may be fluidically coupled with the conduit 106, via a first end of the conduit 106. The fluid reservoir 102 may receive the cooled coolant fluid from the coolant fluid supply via the inlet port 108. The coolant fluid may be introduced into the fluid reservoir 102 at a temperature of 25 °C. As such, at the time of entering the fluid reservoir 102, the temperature of the coolant is relatively lower (as indicated by Blue color near the inlet port 108 and the outlet port 110). The cooled coolant fluid, upon being received in the fluid reservoir 102, may then exit the fluid reservoir 102 via the outlet port 110, to be circulated throughout the conduit 106. The coolant fluid during circulation may absorb heat from the electric motor 100B that may cause a temperature rise of the coolant fluid. The heated coolant fluid, upon circulation, may exit conduit 106 via a second end of the conduit 106, at a relatively higher temperature (as indicated by Yellow color near the second end of the conduit 106). For example, the heated coolant fluid may exit the conduit 106 at a temperature of around 98 °C.
[031] The coolant fluid may be circulated through the conduit 106 at a mass flow rate of 0.1 kilogram per second kg/sec. To this end, the coolant fluid may be circulated through the conduit 106 via a pump (not shown in FIG. 1). For example, the pump may be positioned between the coolant fluid supply and the fluid reservoir 102, and therefore, may cause the flow rate of 0.1 kg/sec of the coolant fluid mass. Alternatively, the pump may be positioned between the second end of the conduit 106 and the coolant fluid supply.
[032] The conduit 106 may define the plurality of linear pathways 106A extending along the longitudinal length of the housing 104 of the electric motor 100B. Further, the conduit 106 may define a plurality of bends 106B. Each of the plurality of bends 106B may be fluidically couple with a pair of adjacent linear pathways 106A of the plurality of linear pathways 106A. The plurality of bends 106B may be positioned in proximity to extreme ends of the longitudinal length of the housing 104 of the electric motor 100B. Further, the conduit 106 may define a plurality of bends 106B.
[033] In some embodiments, the inlet port 108 may be fluidically coupled with a coolant fluid supply (not shown in FIG. 1). Further, the outlet port 110 may be fluidically coupled with the conduit 106, via a first end of the conduit 106. In other words, the fluid reservoir 102 may receive the cooled coolant fluid from the coolant fluid supply via the inlet port 108. In some embodiments, the coolant fluid may be introduced into the fluid reservoir 102 at a temperature of 25 °C.
[034] The coolant fluid supply, for example, may be a radiator which may cause heat exchange between a heated coolant fluid and a cold medium (for example, atmospheric air) to thereby remove heat and cool down the coolant fluid. This cooled coolant fluid, upon being received in the fluid reservoir 102, may then exit the fluid reservoir 102 via the outlet port 110, to be circulated throughout the conduit 106. The coolant fluid during circulation may absorb heat from the electric motor 100B that may cause a temperature rise of the coolant fluid. The heated coolant fluid, upon circulation, may exit the conduit 106 via a second end of the conduit 106. For example, the heated coolant fluid may exit the conduit 106 at a temperature of around 98 °C. The conduit 106 is therefore configured to release the coolant fluid to the coolant fluid supply, via the second end of the conduit 106. The heated coolant fluid may then enter the coolant fluid supply, and the cycle may continue.
[035] It should be noted that the temperature of 25 ?C of the coolant fluid with a at the time of entry and the mass flow rate of 0.1 kg/sec is selected for maximum efficiency of heat removal by the coolant fluid. Further, during simulation study of the cooling system 100A, it is observed that when the coolant fluid is introduced at the temperature of 25 ?C and the mass flow rate of 0.1 kg/sec, the outlet temperature obtained is near about 98 ?C. The simulation study is performed considering the electric motor temperature of 120 ?C (which is a standard temperature of a three-phase AC induction motor at loading condition). Thus, a gain of 73 ?C during circulation indicates a successful functioning of the cooling system.
[036] Referring now to FIG. 3, another schematic perspective view of the cooling system 100A is illustrated, in accordance with some embodiments. As mentioned above, the cooling system 100A may include the fluid reservoir 102 and the conduit 106 fluidically coupled with the fluid reservoir 102. As further mentioned above, the fluid reservoir 102 and the conduit 106 may be made from heat conductive material, such as Copper. Further, the thickness of the walls of the fluid reservoir 102 and the conduit 106 may be 1 mm. This configuration (i.e. the material and thickness) of the fluid reservoir 102 and the conduit 106 may be selected for maximum efficiency.
[037] Further, the above configuration of the fluid reservoir 102 and the conduit 106 is known to display a similar behavior to the constrained simulation where the temperature of the surface reaches nearly the load temperature of 120 ?C. This is due to the high thermal conductivity of Copper which is near to 400 watts per meter-kelvin (Watt/mK).
[038] Referring now to FIG. 4, a schematic diagram of the fluid reservoir 102 showing the coolant fluid flow gradient therein is illustrated, in accordance with some embodiments. The fluid reservoir 102 is configured to perform two functions - firstly, to provide a large contact surface via the bottom reservoir-surface 102A. The large contact surface of the bottom reservoir-surface 102A may provide for a heat flux of 500 Watts/meter square (W/m2). Secondly, the fluid reservoir 102 is configured to store the coolant fluid before the initialization of the operation of the cooling system 100A. Before initialization of the operation of the cooling system 100A, the coolant fluid is stored inside the fluid reservoir 102. Due to a constant temperature and pressure, the specific heat capacity of the coolant fluid is nearly 4184 J/Kg K based on which the desired heat transfer load (3 kilo Watts) is calculated. The fluid reservoir 102 further helps in creating the fluid waveform (isolines) inside, due to which it takes around 1.3 seconds of time for the coolant fluid to move through the fluid reservoir 102 which is sufficient to provide the required heat flux.
[039] Referring now to FIG. 5, another schematic perspective view 500 of the cooling system 100A implemented on the electric motor 100B is illustrated, in accordance with some embodiments of the present disclosure. FIG. 5 further illustrates a direction of heat transfer in the colling system 100A. The arrows represent the heat flux waveform moving outward from the core of the electric motor 100B. Further, the heat flux variation is depicted by the working fluid lines changing color gradient from Blue to Orange, on extracting the heat from the electric motor 100B.
[040] Th above disclosure provides for a cooling system especially for electric motors of the electric vehicles. The above cooling system uses a Copper-based cooling jacket with a primary reservoir on the electric motor for maximum heat absorption. Further, the cooling system has a geometry of the conduit that defines a plurality of linear pathways and a plurality of bends for an efficient performance of the cooling system. The above cooling system is independent of a type of coolant fluid or a geometry being used to envelope the electric motor, and is suitable for various different coolant fluids and electric motors.
[041] It is intended that the disclosure and examples be considered as exemplary only, with a true scope and spirit of disclosed embodiments being indicated by the following claims.
,CLAIMS:We claim:
1. A cooling system (100A) for an electric motor (100B), the cooling system (100A) comprising:
a fluid reservoir (102) configured to receive therein and supply a coolant fluid,
the fluid reservoir (102) positioned on a top side of a housing (104) of the electric motor (100B),
the fluid reservoir (102) defining:
a bottom reservoir-surface (102A) in thermal contact with a housing-surface associated with the top side of the housing (104) of the electric motor (100B); and
a conduit (106) fluidically coupled with the fluid reservoir (102) and configured to circulate the coolant fluid therethrough,
the conduit (106) enveloping the housing (104) of the electric motor (100B),
the conduit (106) defining a plurality of linear pathways (106A) extending along a longitudinal length of the housing (104) of the electric motor (100B),
a plurality of bends (106B), each of the plurality of bends (106B) fluidically coupling a pair of adjacent linear pathways (106A) of the plurality of linear pathways (106A), and
the plurality of bends (106B) being positioned in proximity to extreme ends of the longitudinal length of the housing (104) of the electric motor (100B).

2. The cooling system (100A) as claimed in claim 1, wherein the fluid reservoir (102) is configured in a rectangular shape defining:
the bottom reservoir-surface (102A);
a top reservoir-surface (102B) disposed opposite to the bottom reservoir-surface (102A); and
a plurality of side walls (102C) defined between the bottom reservoir-surface (102A) and the top reservoir-surface (102B),
wherein each of the bottom reservoir-surface (102A) and the top reservoir-surface (102B) has measurements of 200 millimeters (mm) x 400 mm.

3. The cooling system (100A) as claimed in claim 1, wherein thickness of the bottom reservoir-surface (102A), the top reservoir-surface (102B), and the plurality of side walls (102C) is 1 mm.

4. The cooling system (100A) as claimed in claim 1, wherein the fluid reservoir (102) is fluidically coupled to the conduit (106) via:
an inlet port (108); and
an outlet port (110),
wherein each of the inlet port (108) and the outlet port (110) is configured in a circular cross-section, and
wherein diameter of the each of the inlet port (108) and the outlet port (110) configured in the circular cross-section is 10 mm.

5. The cooling system (100A) as claimed in claim 4,
wherein the inlet port (108) is fluidically coupled with a coolant fluid supply; and
wherein the outlet port (110) is fluidically coupled with the conduit (106), via a first end of the conduit (106).

6. The cooling system (100A) as claimed in claim 5, wherein the conduit (106) is configured to release the coolant fluid to the coolant fluid supply via a second end of the conduit (106).

7. The cooling system (100A) as claimed in claim 1,
wherein the conduit (106) is configured in a circular cross-section, and
wherein diameter of the conduit (106) is 10 mm.

8. The cooling system (100A) as claimed in claim 1, wherein each the fluid reservoir (102) and the conduit (106) is made of material selected from one of Copper, Aluminum, and alloys thereof.

9. The cooling system (100A) as claimed in claim 1, wherein the plurality of linear pathways (106A) comprises twelve linear pathways (106A).

10. The cooling system (100A) as claimed in claim 1, wherein each of the plurality of bends (106B) is configured in a semi-circular shape.

11. The cooling system (100A) as claimed in claim 1, wherein the coolant fluid is circulated through the conduit (106) at a mass flow rate of 0.1 kilogram per second (kg/sec), wherein the coolant fluid is circulated through the conduit (106) via a pump.

12. The cooling system (100A) as claimed in claim 1, wherein the coolant fluid is introduced at a temperature of 25 °C.