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Title:
A LIQUID - COOLED COOLING METHOD FOR ELECTRIC MOTORS AND ALTERNATORS
Document Type and Number:
WIPO Patent Application WO/2022/086459
Kind Code:
A1
Abstract:
The present invention relates to a cooling system for an alternator (10) or an electric motor, comprising a rotor (13), a stator (14), a fan (15) coupled to the said rotor (13) shaft, a cooling jacket (12) externally cooling the said stator (14), and air cooling fins (123) structured around the cooling jacket (12) to ensure one - way cooling of the rotor (13) and two - way cooling of the stator (14) by forming an expanded heat transfer area to cool the air circulated in closed loop by the fan (15).

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Inventors:
DERELİ İZZET (TR)
Application Number:
PCT/TR2020/050966
Publication Date:
April 28, 2022
Filing Date:
October 21, 2020
Export Citation:
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Assignee:
DERELI IZZET (TR)
International Classes:
H02K1/20; H02K9/06
Foreign References:
US20190173351A12019-06-06
Attorney, Agent or Firm:
DESTEK PATENT, INC. (TR)
Download PDF:
Claims:
CLAIMS An alternator (10) cooling system comprising a rotor (13), a stator (14), a fan (15) coupled to the said rotor (13) shaft, and a cooling jacket (12) externally cooling the said stator (14), characterized by comprising air cooling fins (123) structured around the cooling jacket (12) to ensure one - way cooling of the rotor (13) and two - way cooling of the stator (14) by forming an expanded heat transfer area to cool the air circulated in closed loop by the fan (15). An alternator (10) cooling method comprising the process steps of externally cooling a stator (14) by way of a liquid coolant circulated in a cooling jacket (12) and inducing air circulation inside the alternator housing (11 ) by way of a fan (15 coupled to the rotor (13) shaft, characterized by comprising of the following steps; a) Guiding the air circulated by the said fan (15) to the air cooling fins (123) of the cooling jacket (12); b) cooling the circulated air by way of heat transfer between the air cooling fins (123); and c) ensuring one - way cooling of the rotor (13) and stator (14) and two - way cooling of the cooling jacket (12) and stator (14) by circulating the cooled air in a closed - loop system.
Description:
A LIQUID - COOLED COOLING METHOD FOR ELECTRIC MOTORS AND ALTERNATORS

Field of the Invention

The present invention relates to a cooling system with a cooling jacket.

The invention specifically relates to a cooling system with a cooling jacket and a cooling method designed to eliminate the heat produced during the operation of alternator, electric motor or similar configurations.

Prior Art

Alternator, which converts mechanical energy to electric energy, and electric motor, which converts electric energy to mechanical energy, produce heat during their operation. Excessive heat reduces the efficiency of products, in some cases, permanently damages the magnetic properties of magnets and coil insulation. For this reason, it is crucial to eliminate the generated heat and optimize cooling efficiency.

The heat generated by electric motors and alternators is cooled by employing methods: air cooling and water cooling. The existing cooling systems in the literature are as listed below:

Patent application no. EP3211761 B1 relates to an air - cooled electric machine. The electric machine in question comprises a rotor with rotor cooling channels connected in a rotationally fixed manner to a rotor shaft, a stator having stator cooling channels, a housing tube, both sides arranged bearing shields with bearings for rotatably receiving the rotor shaft, with air inlets and air outlets, and at least one fan connected to the rotor shaft for guiding the cooling air. To improve cooling and reduce noise development, a fan is arranged on both sides, each formed by a combined by a radial I axial fan, wherein the stator cooling channels are interrupted by a barrier and the ends of the stator cooling channels on both sides of the barrier with in the housing tube arranged air outlets are connected, so that the cooling air from the air inlets in one direction through the axial rotor cooling channels are separated by in the opposite direction the axial stator cooling channels to the barrier and the air outlets.

Patent application no. EP3043450B1 relates to motor with a heat dissipation structure capable of restraining temperature therein. The invention in question includes a substantially cylindrical housing, a rotor assembly, a cover, a sleeve, and a cooling fan. The cooling fan is installed at one end of a rotating shaft of the rotor assembly to induce airflow. The sleeve, being closely fitted around the housing, is integrally formed with a plurality of wind - caching projection, each of which is located above one upstream through hole defined on the housing and faces towards the cooling fan. The wind - catching projections can receive the airflow induced by the cooling fan and guides the airflow to enter the housing via the upstream through holes to dissipate the heat accumulated in the motor, so that the motor can be prevented from damaged due to heat accumulation. Therefore, the performance and service life of the motor can be increased.

Patent application no. US5859482 relates to a liquid cooled electric motor. In an exemplary embodiment, the conduit is arranged in a generally helical geometric configuration and the stator frame is cast around the conduit. The stator frame with the cast in place cooling conduit has the advantages of a liquid cooled motor yet is believed to be lower cost than known liquid cooled motors. The motor also is believed to be less susceptible to corrosion and liquid leaks as compared to known liquid cooled motors.

Patent application no. US7545060 relates to a method and apparatus for heat removal from electric motor winding end - turns. An electric motor includes a stator having a plurality of slots. The slots have slot ends and channels formed between the slot ends. A plurality of wire windings is disposed in the slots. The electric motor also includes a cooling tube connected to a periphery formed by the winding end - turns. The cooling tube is operable to absorb heat from the electric motor. The cooling tube can cool the winding end - turns more efficiently than traditional electric motor water jackets and I or cooling fans. This invention is based on the principle of encircling winding end - turns with a plurality of cooling tubes and circulating coolant through the cooling tubes. Patent application no. US7675209 relates to an electric motor cooling jacket. The cooling jacket according to the invention includes a cylindrical inner sleeve, a cylindrical outer sleeve coaxially surrounding the inner sleeve and forming a circular space between the outer sleeve and the inner sleeve and forming a circular space between the outer sleeve and the inter sleeve, and a passageway extending within the circular space between the outer sleeve and the inner sleeve. The passageway may be a continuous winding path that may extend axially back and forth along the circumference of said inner sleeve. The cooling jacket as in one embodiment of the present invention may be leak proof and watertight, has a compact design, and may be easily assembled and integrated into an electrically driven machine, such as an electrically driven compressor.

Patent application no. EP2182619B1 relates to an arrangement for cooling of an electrical machine. The electrical machine comprises a rotor, a stator, while an airgap is between the rotor and the stator. The electrical machine comprises an air - cooling arrangement, which circulates air inside the electrical machine. The electrical machine comprises a liquid - cooling arrangement, which circulates cooling - liquid inside the electrical machine. The air - cooling arrangement and the liquid - cooling arrangement are connected by an air - to - liquid heat exchanger, which is applied to transport heat out from the electrical machine the cooling liquid.

Patent application no. US9692277 relates generally to electric motors and, more particularly, to a thermal management system for use with an integrated motor assembly. The common thermal management system according to the invention includes a liquid coolant loop that is thermally coupled to the electric motor, the power inverter assembly and the gearbox. Liquid coolant is supplied to the core of the motor rotor, the outer housing of the motor stator, the gearbox and the drive inverter electronic components. In the illustrated embodiment, unlike the conventional methods, the liquid coolant supplied to the rotor and stator requires additional insulation in stator winding wires and since the alternator is fully filled with liquid inside, additional sealing methods are necessary to prevent liquid leak from the inside to the outside.

Patent application no. US20100007227A1 relates to a cooling jacket. The said cooling jacket for a motor includes an extruded jacket body having an outer peripheral surface, an inner peripheral surface, and a plurality of discrete cooling passages located between the inner and outer peripheral surfaces that provide multi - directional fluid flow. A fluid inlet is provided to direct cooling fluid into the jacket body and a fluid outlet to direct heated fluid away from the jacket body.

Patent application no. US20190372413A1 relates to a system for cooling an electric machine having two components, one of the two components rotor and the other a stator, the two components enclosing a central axis of the electric machine coaxially. The rotor during operation of the electric machine rotates relative to the stator, wherein at least one axially oriented channel passes through at least one component. A fan is arranged at a first end of the at least one channel, wherein a turbine is arranged at a second end of the at least one channel. The fan is designed to enable air to flow, flowing from the first end to the second end. The said turbine is designed to convert kinetic energy of the flowing air into rotational energy of the component designed as a rotor.

As detailed in the examples above and various other examples, electric motors or alternators are cooled by a cooling jacket and this method involves cooling through transfer from the stator external surface, so the rotor has no contact and cannot be cooled. Only patent application no. US9692277 provides and embodiment for cooling of the rotor, but this method also necessitates further measures, including coating of stators with epoxy, etc. and sealing the alternator chamber. Due to efficiency reasons, heat is principally accumulated in copper winding wires in stator slots in electrical machines. The generated heat needs to cover a long distance to the cooling jacket to remove the heat in the copper winding wires. In systems which employ a cooling jacket, stator can be cooled from the external surface, whereas the rotor cannot be cooled. In configurations employing an air - cooled system, separate cooling arrangements or alternating combined cooling arrangements are used both for the rotor and the stator.

In conclusion, the drawbacks explained above and the shortcomings in existing solutions to the problems have necessitated improvement in the related technical field.

Summary of the Invention The present invention relates to a cooling system with a cooling jacket developed for alternators and electric motors, which satisfies the requirements listed above, eliminates the disadvantages of the prior art while bringing new benefits to the technical field.

The primary aim of the invention is to provide a cooling system with a cooling jacket, which cools both the rotor and the stator to remove heat generated during the operation of an alternator, which converts mechanical energy to electric energy, and an electric motor, which converts electric energy to mechanical energy.

One aim of the invention is to provide a cooling system which optimizes cooling efficiency in electric motors and alternators cooled by a closed - loop liquid coolant method.

Another aim of the invention is to provide a cooling system which allows for an alternator and electric motor with compact design.

One other aim of the invention is to provide a cooling system for use not only in asynchronous alternators, but also in synchronous alternators.

The invention aims to provide a cooling system for alternators and electric motors with improved cooling efficiency and more power and useful life compared to equivalent products.

In order to achieve the aims specified above, the invention relates to a cooling system for alternators, comprising a rotor, a stator, a fan connected to the rotor shaft, and a cooling jacket to externally cool the said stator. Accordingly, the said cooling systems further comprises air cooling fins structured around the cooling jacket to ensure one - way cooling of the rotor and two - way cooling of the stator by forming an expanded heat transfer area to cool the air circulated in closed loop by the fan.

The present invention also relates to an alternator cooling method, comprising the process steps of externally cooling a stator by way of a liquid coolant circulated in a cooling jacket and inducing air circulation inside the alternator housing by way of a fan coupled to the rotor shaft. The said method covers the following process steps: Guiding the air circulated by the said fan to the air cooling fins of the cooling jacket, cooling the circulated air by way of heat transfer between the air cooling fins, and ensuring one - way cooling of the rotor and two - way cooling of the stator by circulating the cooled air in a closed - loop system.

The below drawings and the detailed description referring to these drawings provide for a clearer understanding of the structural and characteristic properties and all benefits of the present invention; therefore, the evaluation needs to take these drawings and the detailed description into account.

Brief Description of the Drawings

Figure 1 shows a disassembled view of an alternator with the cooling system according to the invention.

Figure 2 shows the detailed cross - sectional view of the alternator in A - A and B - B directions.

Figure 3 shows the cross - sectional view of the alternator illustrating closed - loop air circulation in the cooling system according to the invention.

Figure 4 shows a front perspective view of the alternator housing.

Figure 5 shows a detailed front perspective view of the alternator housing.

Figure 6 shows a rear perspective view of the alternator body.

Figure 7 shows a A - A - and B - B cross - sectional view of the alternator housing.

Drawings do not necessarily require scaling and certain details not necessary for understanding the invention may be omitted. Furthermore, at least substantially identical parts or parts with at least substantially identical functions are illustrated with the same reference numerals.

List of Reference Numerals

10 Alternator

11 Alternator Housing

111 Interior Wall

112 Exterior Wall 113 Water Inlet - Outlet

12 Cooling Jacket

121 Jacket Portion

122 Water Guiding Ribs

123 Air Cooling Fins

13 Rotor

14 Stator

15 Fan

A - A: Horizontal Section Direction

B - B Vertical Section Direction

Detailed Description of the Invention

In order to facilitate a better understanding of the present invention, this detailed description demonstrates the alternator (10) cooling system according to the invention in a non - limiting manner.

The cooling system according to the invention is used for removal of the heat generated during operation of an alternator (10) which is illustrated as disassembled in Figure 1 , and functions together with the said alternator (10). The alternator (10) turns the rotor through mechanical action to generate energy through the generated magnetic field. Electric machines such as electric motor magnetize the stator via electrical energy and turn the rotor by way of the resulting magnetic field. Just like the alternator (10), electric machines can be cooled using the cooling system according to the invention.

Figure 2 shows the cross - sectional view of the alternator (10) in A - A and B - B directions, which substantially comprises an alternator housing (11), a stator (14) inside the said alternator housing (11 ), a rotor (13) and a fan (15) coupled to the said rotor (13) shaft. The stator (14) closely fits the alternator housing (11 ) and the rotor (13) and the fan (15) are coupled to the shaft. When installed, there is a certain gap left between the stator (14) and the rotor (13). The cooling system according to the invention comprises a cooling jacket (12) located inside the alternator housing (1 1 ) to deliver cooling efficiency together with the said fan (15). Figure 3 shows the closed - loop air circulation provided by the fan (15) of the cooling system inside the alternator housing (1 1 ).

With reference to Figures 4 and 5 for front and rear perspective views and Figure 6 for cross - sectional view, the alternator housing (1 1 ) comprises an interior wall

(1 1 1 ), an exterior wall (1 12) and a water inlet - outlet (1 13) adapted to the housing. The said cooling jacket (12) is defined by the volumetric gap between the said interior wall (11 1 ) and the said exterior wall (1 12). Cooling of the alternator (10) by way of the cooling jacket (12) takes place with the entry and exit of the liquid coolant to the gap, defined as the cooling jacket (12). The cooling jacket (12) comprises a jacket (121 ) in the form of a surface welded to the interior wall (1 1 1 ) so as to contact the stator (14), water guiding ribs (122) extending along the alternator housing (1 11 ) and air cooling fins (123) surrounding the exterior wall

(1 12). The said air cooling fins (123) increase the cooled surface area in the cooling jacket (12), thereby expanding the heat transfer area.

The cooling activity in the alternator (10) simultaneously takes place through the liquid coolant and the air provided by the fan (15). The liquid coolant circulated through the cooling jacket (12) cools the external surface of the stator (14). The air which becomes warmers after getting filtered through the gap between the rotor

(13) and the stator (14) by means of the fan (15) is cooled by heat transfer which takes place in the cooled air cooling fins (123) in air cooling channels. The cooled air enables one - way cooling of the rotor (13) and two - way cooling of the stator

(14). The air - cooling effect continues uninterruptedly as long as the cooling system is operational.

The cooling system according to the invention both cools the rotor (13) and improves the cooling efficiency of the stator (14) through the air circulating in closed loop. This makes it possible to attain more power from the alternator (10) and electric motors with longer useful life. Moreover, more compact alternator and electric motor designs can be achieved. This enables drawing more power from the alternator (10) and electric motor with more compact designs and extended useful life. Since the cooling system according to the invention also cools the rotor (13), the cooling system and method according to the invention can be used not only for cooling asynchronous alternators, but also for cooling synchronous alternators.