KR102634868B1 - Heat pipe and motor cooled thereby - Google Patents

Abstract

In the present invention, the heat pipe is mounted on the motor rotation shaft of the motor and rotates, and the flow impeller fixed inside the heat pipe rotates along with the rotation of the motor rotation shaft to force the gaseous working fluid in the evaporation section to flow to the condensation section, thereby forming the heat pipe. This is a technology to increase the cooling efficiency of the motor and thereby effectively control the heat generation of the motor.

Description

Heat pipe for motor cooling and motor cooled thereby {HEAT PIPE AND MOTOR COOLED THEREBY}

The present invention relates to a heat pipe for cooling a motor, and relates to a heat pipe that is mounted on the motor rotation shaft of a motor to cool the motor.

An electric motor is a device that can convert electrical energy into mechanical energy.

When current is supplied to an electric motor, heat is generated due to electrical loss caused by copper loss caused by the resistance of the coil or conductor, resistance of the iron core material when the magnetic force line passes, and iron loss generated in the iron core to magnetize the iron core. Some of the heat accumulates within the motor, and the rest is dissipated to the outside through radiation, convection, and conduction.

During motor operation, the temperature rises due to the difference between the amount of heat generated inside the motor and the amount of heat released outside the motor. When the temperature rises, the winding section, where the temperature is highest, deteriorates and causes a short circuit, which limits the use of the motor. Limited by ambient temperature and motor temperature rise.

A typical existing air-cooled motor includes a stator including a stator coil to generate magnetic force when power is applied, a rotor that rotates by the magnetic force of the stator, a motor rotation shaft that is the central axis of the rotor, and the motor rotation shaft operates smoothly. A bearing is provided to rotate, and a cooling fan is installed on one side of the motor rotation shaft to cool the motor.

At this time, the main heat source of the motor is the stator coil, and the heat generated by the rotor is dissipated through the motor rotation shaft and through the air gap between the rotor and stator.

The main heat sources of the motor configured as above are the rotor and stator coil, and the cooling fan installed on one side of the motor rotation shaft rotates together with the motor rotation shaft to generate wind to cool the motor, thereby increasing the cooling efficiency of the motor.

The surface of the stator coil is coated with an insulating film, and the lifespan of the insulating film is inversely proportional to the rise in temperature, so if the heat generated by the stator coil is not smoothly dissipated to the outside, the insulating film may deteriorate and peel off or be destroyed.

However, these air-cooled motors have many difficulties in effectively dissipating the heat generated from the stator coil and rotor to the outside. To overcome the limitations of the air-cooled cooling structure, motors using a water-cooled cooling structure have been developed domestically and internationally. Although it is being applied, the water-cooled type has the disadvantage that a cooler, which is an auxiliary facility, must be installed.

Meanwhile, if the driving speed of the electric vehicle motor is increased, it is possible to design a small, high-output driving motor. Currently, permanent magnet motors are limited to a maximum operating speed of 10,000 rpm, and induction motors can operate at a maximum operating speed of approximately 13,000 rpm.

Even with the same size of drive system, products with excellent cooling performance can increase power density, and there is a need for an efficient cooling system that goes beyond the water-cooled cooling channel method of existing housings.

Meanwhile, heat pipes are widely known as a type of cooling device.

Figure 5 is a conceptual cross-sectional view of a conventional heat pipe.

Since the working fluid is injected into the heat pipe before the hollow part inside the heat pipe body 14 is vacuum formed and then sealed, the internal pressure is determined by the vapor pressure of the working fluid.

The heat pipe has an evaporation part 11 formed on one side and a condensation part 12 on the other side. In the evaporation part, the liquid working fluid is evaporated into gaseous working fluid, and in the condensation part, the gaseous working fluid is condensed into liquid working fluid. do.

Specifically, when heat is transferred to the evaporation unit (when heat is absorbed from the outside), the liquid working fluid is vaporized (evaporated) and a pressure difference is generated in the hollow part inside, and the gaseous working fluid vaporized by this pressure difference moves into the hollow part inside. It moves along the section to the condensation section, where temperature and pressure are low, and in the condensation section, the gaseous working fluid radiates latent heat of evaporation (radiating heat to the outside) and condenses into the liquid working fluid.

The condensed liquid working fluid returns to the evaporation unit by the capillary force generated in the wick (13) structure.

In other words, the heat pipe absorbs external heat in the evaporation section, evaporates the working fluid injected in a vacuum state into a closed space, converts it to a gaseous working fluid, and then flows to the condensation section, dissipating heat to the outside and cooling it. It becomes a liquid working fluid again, and the condensed liquid working fluid returns to the evaporation part by the capillary force of the wick, causing circulation of the working fluid.

The operating range of the heat pipe is divided into cryogenic temperature (0∼150K), low temperature (150∼750K), and high temperature (750∼3000K) depending on the freezing point and boiling temperature of the working fluid.

High-temperature heat pipes are used in the energy industry for cooling nuclear reactors and radioactive isotopes, and waste heat recovery devices, while low-temperature heat pipes are used for cooling and control of electronic circuits, rotating shafts, and turbines. It is used in many fields such as cooling of transformers, storage and application of solar energy collection, and greenhouse heating systems.

Republic of Korea Patent No. 10-0665048 “Rapid cooling structure of motor using heat pipe” (registered on December 28, 2006)

The present invention was developed to solve the problems of the prior art as described above. The heat pipe is mounted on the motor rotation shaft of the motor and rotates, and the flow impeller fixed inside the heat pipe rotates together with the rotation of the motor rotation shaft. By forcing the gaseous working fluid from the evaporation unit to flow into the condensation unit, the cooling efficiency of the heat pipe is increased and thereby the heat generation of the motor is effectively controlled.

In order to solve the above problem, the present invention provides a heat pipe having an evaporation part in which the liquid working fluid evaporates into a gaseous working fluid and a condensation part in which the gaseous working fluid is condensed into a liquid working fluid, wherein the heat pipe is connected to the motor rotation shaft. When mounted and rotated, it rotates together with the heat pipe, and when the heat pipe is mounted on the motor rotation shaft and does not rotate, it is fixed between the evaporation unit and the condensation unit so that it does not rotate together with the heat pipe, and the heat pipe and It is characterized in that a flow impeller is provided to force the gaseous working fluid of the evaporation unit to flow to the condensation unit when rotated together.

In the above, the impeller for flow is preferably in the form of a screw.

In the above, internal heat conduction fins are formed to protrude inward on the inner wall of the heat pipe body forming the condensation portion, and the internal heat conduction fins are formed continuously in a spiral shape so that the heat pipe is mounted on the motor rotation shaft of the motor and rotates. When possible, it is desirable to force the liquid working fluid of the condensation unit to flow toward the evaporation unit.

In the above, the flow impeller is preferably fixed to the inside of a pipe-shaped coupling tube, and the outer peripheral surface of the coupling tube is fixed to the internal heat conduction fin.

In the above, external heat conduction fins are formed to protrude outward on the outer wall of the heat pipe body forming the condensation portion, and the external heat conduction fins are formed continuously in a spiral shape so that the heat pipe is mounted on the motor rotation shaft of the motor and rotates. When doing so, it is desirable to forcibly blow the gas outside the heat pipe body.

In another aspect of the present invention, a motor is provided in which the heat pipe for motor cooling is mounted on the motor rotation shaft.

As described above, in the present invention, the heat pipe is mounted on the motor rotation shaft and rotates together with the motor rotation shaft, and the flow impeller fixed inside the heat pipe rotates together with the rotation of the motor rotation shaft to transfer the gaseous working fluid from the evaporation section to the condensation section. By forcing flow, the cooling efficiency of the heat pipe can be increased.

As a result, the present invention effectively controls the heat generation of the motor, prevents the temperature of the motor's rotor and stator coil from increasing, and prevents the motor lifespan from being shortened due to insulation breakdown or deterioration of the insulation in the winding area due to temperature rise. there is.

In addition, the present invention increases the efficiency of the motor and enables long-term use of the motor, and its effectiveness is especially high in electric vehicle motors in poor use environments.

1 is a conceptual cross-sectional view of a motor cooled by a heat pipe according to an embodiment of the present invention;
Figure 2 is an exploded cross-sectional view of Figure 1;
Figure 3 is a conceptual cross-sectional view of the heat pipe of Figure 1;
Figure 4 is a diagram showing a Molière diagram according to the change in evaporation pressure of the heat pipe according to an embodiment of the present invention;
Figure 5 is a conceptual cross-sectional view of a conventional heat pipe.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

An embodiment according to the present invention will be described.

FIG. 1 is a conceptual cross-sectional view of a motor cooled by a heat pipe according to an embodiment of the present invention, FIG. 2 is an separated cross-sectional view of FIG. 1, FIG. 3 is a conceptual cross-sectional view of the heat pipe of FIG. 1, and FIG. 4 is the main This is a diagram showing the Molière diagram according to the change in evaporation pressure of the heat pipe according to an embodiment of the invention.

This embodiment consists of a motor 100 and a heat pipe 200 for motor cooling.

The motor 100 includes a stator 101 including a coil so that magnetic force is generated when power is applied, a rotor 102 that rotates by the magnetic force of the stator 101, and a rotor 102 installed in the central portion of the rotor 102 to generate magnetic force. It includes a motor rotation shaft 103 that rotates together with the electrons 102, an air gap 104 formed between the stator 101 and the rotor 102, etc.

A mounting groove 103a is formed on one side of the motor rotation shaft 103 toward the center, and a portion of the motor cooling heat pipe 200 is inserted and mounted into the mounting groove 103a.

The heat pipe 200 for motor cooling of this embodiment includes a heat pipe body 210, a wick 220, a coupling pipe 230, and an impeller 240 for flow.

The heat pipe body 210 has a shape that extends long in the longitudinal direction and has a hollow portion formed therein to form a sealed structure.

Materials for the hippipe body 210 include aluminum, copper, and stainless steel. Copper is preferred, but is not particularly limited.

The working fluid enclosed inside the heat pipe body 210 includes Helium, Argon, and Nitrogen for cryogenic use (0~150K), and for low temperature use (150~750K). Water, Ethanol, Methanol, Acetone, Ammonia, Freon, etc. For high temperature use (750~3000K), Caesium and Sodium are used. ), lithium, etc., but low-temperature water, ethanol, methanol, acetone, freon, etc. are preferred, but are not particularly limited.

Inside the heat pipe body 210, one longitudinal side is an evaporation unit 201 and the other longitudinal side is a condensation unit 202.

In the evaporation unit 201, the liquid working fluid (L) is evaporated into a gaseous working fluid.

The heat pipe body 210 on one longitudinal side forming the evaporation unit 201 is mounted on the mounting groove 103a of the motor rotation shaft 103, and cools the motor by absorbing heat generated from the motor.

In the condensation unit 202, the gaseous working fluid is condensed into a liquid working fluid.

The heat pipe body 210 on the other longitudinal side forming the condensation unit 202 is disposed outside the motor 100 to dissipate heat to the outside.

In the heat pipe body 210 forming the condensation unit 202, internal heat conduction fins 211 are formed to protrude inward on the inner wall, and external heat conduction fins 212 are formed to protrude outward on the outer wall.

The internal heat conduction fins 211 are continuously formed in a spiral shape and are used to force the liquid working fluid in the condensation unit 202 to flow toward the evaporation unit 201.

In addition, a hollow portion is formed in the center of the internal heat transfer fin 211, thereby increasing the heat exchange efficiency by increasing the heat transfer area without interfering with the flow of the gas working fluid (G).

The internal heat conduction fins 211 are continuously connected in the form of a spiral, screw, or helical gear, and the blade pitch of the spiral internal heat conduction fins 211 is inclined in one direction (i.e. toward the evaporation unit) and the inclined Allow flow to occur in that direction. The blade pitch angle of the screw-shaped internal heat conduction fin 211 is preferably 5° to 15° based on the normal line.

The external heat conduction fins 212 are formed continuously in a spiral shape to forcefully blow gas outside the heat pipe 200 toward the motor 100 when the heat pipe 200 is mounted on the motor rotation shaft 103 and rotated. It is for.

The external heating fins 212 are continuously connected in the form of a spiral, screw, or helical gear, and the blade pitch of the external heating fins 212 in the spiral shape is inclined in one direction (i.e., toward the motor) and is tilted in the inclined direction. to allow flow to occur. The blade pitch angle of the screw-shaped external heat conduction fin 212 is preferably 3° to 10° based on the normal line.

The heat pipe body 210 is disposed along the center line of the motor rotation axis 103.

Therefore, the heat pipe body 210 rotates coaxially with the motor rotation shaft 103.

A wick 220 is provided inside the heat pipe body 210.

In this embodiment, the wick 220 is provided on the inner wall of the heat pipe body 210 from the flow impeller 240 to the entire evaporation unit 201.

A coupling pipe 230 is fixed inside the heat pipe body 210. Specifically, the outer peripheral surface of the pipe-shaped coupling pipe 230 is fixed to the internal heat conduction fin 211.

An impeller 240 for flow is fixedly provided inside the coupling pipe 230.

This is to fix the flow impeller 240 via the coupling pipe 230 in order to solve the problem that it is difficult to directly fix the screw-type flow impeller 240 to the internal heat transfer fin 211.

The flow impeller 240 is for forcing the gaseous working fluid of the evaporation unit 201 to flow into the condensation unit 202 when the heat pipe 200 is mounted on the motor rotation shaft 103 and rotated, and the flow impeller 240 ), a pressure difference between the evaporation unit 201 and the condensation unit 202 is generated. Of course, the flow impeller 240 does not rotate together with the heat pipe 200 when the heat pipe 200 is mounted on the motor rotation shaft 103 and does not rotate (that is, when the motor does not rotate).

The flow impeller 240 may be any type of impeller as long as it can force the gas working fluid to flow in any direction using rotational force.

In this embodiment, the flow impeller 240 can be manufactured in a small size with an extremely simple structure by adopting a screw shape, and can be inserted and fixed into the coupling pipe 230 or the heat pipe body 210.

The screw-type flow impeller 240 is continuously connected in the screw form or helical gear type, and the blade pitch of the screw-type flow impeller 240 is inclined in one direction (i.e., toward the condensation part) and is tilted in the inclined direction. Let the flow occur. The blade pitch angle of the screw-type flow impeller 240 is preferably inclined to the left and is 25° to 30° relative to the normal line.

In addition, the flow amount and pressure difference of the gas operating fluid can be adjusted by adjusting the number of blades of the screw-type flow impeller 240 according to the rotation speed of the motor rotation shaft 103.

Next, the operation of the present invention will be explained.

When the motor 100 is energized, the rotor 102 and the motor rotation shaft 103 rotate continuously.

Accordingly, the heat pipe 200 inserted and fixed into the mounting groove 103a of the motor rotation shaft 103 also rotates.

Rotation of the heat pipe 200 means that the heat pipe body 210 rotates along the axial center of the motor rotation axis 103, and as the heat pipe body 210 rotates, the coupling pipe 230 and the flow impeller (240), both the internal heating fin 211 and the external heating fin 212 rotate along the axis center of the motor rotation shaft 103.

The evaporation unit 201 of the heat pipe 200 operates as a gas by vaporizing (evaporating) the liquid working fluid (L) while absorbing the heat transferred from the stator 101 and the rotor 102 of the motor 100. The phase changes to the fluid (G), and the phase-changed gaseous working fluid (G) moves to the condensation unit (202).

The flow impeller 240 rotates together with the motor rotation shaft 103 and forces the gaseous working fluid (G) of the evaporation unit 201 to flow into the condensation unit 202.

That is, the gaseous working fluid (G) in the evaporation unit 201 is forced to convect to the condensation unit 202 by the flow impeller 240. As a result, the cooling efficiency of the heat pipe 100 can be increased by increasing the circulation speed of the working fluid.

In addition, the pressure of the evaporation unit 201 is lowered and the pressure of the condensation unit 202 is increased due to the forced flow of the flow impeller 240.

Referring to FIG. 4, when the pressure of the evaporation unit 201 decreases from P1 to P2, the change in enthalpy of the liquid working fluid (L) increases from E1 to E2, resulting in evaporation of the liquid working fluid (L). As latent heat increases, the cooling effect of the heat pipe 20 can be increased, thereby effectively preventing the temperature of the motor 100 from rising.

That is, the cooling efficiency can be significantly increased by increasing the circulation speed of the working fluid and lowering the pressure of the evaporation unit 201 by the flow impeller 240.

In the condensation portion 202 of the heat pipe 200, the gaseous working fluid (G) changes phase into the liquid working fluid (L) while dissipating heat into the external air, and then flows through the evaporation portion (201) along the wick 220. ) to complete one cooling cycle.

At this time, the internal heat transfer fins 211 serve to expand the heat transfer area and forcibly transfer the liquid working fluid (L) to the wick 220.

The internal heat transfer fins 211 are continuously connected to the inner wall of the heat pipe body 210 in a spiral shape (or helical gear type) and are formed to the flow impeller 240 (or coupling pipe 230), providing a large heat transfer area. This increases heat transfer in the condensation unit 202.

In addition, when the heat pipe 200 rotates at high speed according to the high-speed rotation of the motor 100, the liquid working fluid (L) condensed on the inner wall of the condenser 20 adheres to the surface due to centrifugal force, forming the wick 220. Considering that it is difficult to move to , the liquid working fluid (L) is forced to flow toward the evaporation unit through the spiral-shaped internal heat transfer fin 211.

The internal heat transfer fins 211 are continuously connected in a spiral form (or screw form or helical gear type), and the blade pitch is inclined in the direction of the wick 220, so that the liquid working fluid (L) is forcibly transferred to the wick 220. do.

In this way, by forcibly transferring the liquid working fluid (L) to the wick 220, the supply of the liquid working fluid (L) to the wick 220 is smooth, thereby increasing the heat recovery rate.

The liquid working fluid (L) forcefully transferred to the wick 220 returns to the evaporation unit 201 by capillary pressure.

Meanwhile, the external heat transfer fins 212 expand the heat transfer area and are continuously connected in a spiral form (or screw form or helical gear type), and the blade pitch is inclined in the direction of the motor 100, so that the external heat pipe 200 Air is forcibly blown toward the motor 100 to cool the external heat conduction fins 212 and the motor 100.

As described above, in the present invention, the liquid working fluid changes phase into a gaseous working fluid in the evaporation unit 201, and the gaseous working fluid in the evaporation unit 201 is forced to flow to the condensation unit 202 by the flow impeller 240. The gaseous working fluid changes phase into a liquid working fluid in the condensation part 202, and the liquid working fluid in the condensation part 202 is forcibly transferred to the wick 220 by the spiral-shaped internal heat transfer fin 211. While quickly repeating the process of returning to the evaporation unit 201 along the wick 220, the evaporation unit 201 absorbs heat generated from the motor 100, and heat is released into the external atmosphere in the condensation unit 202. It emanates.

Meanwhile, the automobile industry is gradually changing interest in electric vehicles worldwide, and during research and development in the electric automobile industry, technology to improve the performance of electric motors that replace engines is being developed by making the motor smaller and lighter as part of the miniaturization and weight reduction of electric motors. The cooling method of the motor that can improve is very important.

Since the electric vehicle motor replaces the engine that played the role of the existing internal combustion engine, a large amount of current is applied to satisfy the high torque and high-speed rotation characteristics of the vehicle driving section that the internal combustion engine handled. Due to the large applied current, very high heat is continuously generated in the internal parts of the motor.

Therefore, the heat generated in the motor causes a decrease in the output and efficiency of the motor system, and ultimately reduces its lifespan. Therefore, in the design of electric motors, cooling design using heat transfer technology, along with the electromagnetic field, has become an important technology field.

The rotation speed of this electric vehicle motor in the low-speed section of continuous output is 3,000 rpm, and the rotation speed in the high-speed section is 12,000 rpm. In this way, the pressure of the discharged gas can be adjusted by adjusting the number of blades of the flow impeller 240 according to the rotation speed of the motor. In other words, low-speed motors can increase the discharge pressure by increasing the number of screw-type blades, and high-speed motors can obtain appropriate discharge pressure by reducing the number of screw-type blades.

The air volume by static pressure of the screw-type flow impeller 240 increases linearly as the pitch angle of the blade increases. Therefore, as the pitch angle increases, the axial power increases proportionally, and the increase increases as the pitch angle increases. This is because the larger the pitch angle, the greater the drag in front of the compression section, so based on a 1800 RPM motor, the pitch angle of the wing is preferably in the range of 20° to 35° based on the normal, and even more preferably, the pitch angle of the wing is 25°. °∼30°. However, as the rotation speed increases, the pitch angle may gradually decrease.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: motor
101: stator 102: rotor
103: Motor rotation shaft 103a: Mounting groove
104: air gap
200: Heat pipe for motor cooling
201: Evaporation unit 202: Condensation unit
210: Heat pipe body 211: Internal heating fin
212: External heating fin
220: Wick
230: coupling pipe
240: Impeller for flow

Claims (6)

In the heat pipe, which has an evaporation section in which the liquid working fluid is evaporated into a gaseous working fluid and a condensation section in which the gaseous working fluid is condensed into a liquid working fluid,
When the heat pipe is mounted on the motor rotation shaft and rotated, it rotates together with the heat pipe, and when the heat pipe is mounted on the motor rotation shaft and does not rotate, it is fixed between the evaporation section and the condensation section so that it does not rotate together with the heat pipe. A heat pipe for motor cooling, characterized in that a flow impeller is provided to force the gaseous working fluid of the evaporation unit to flow to the condensation unit when rotated together with the heat pipe.
According to claim 1,
A heat pipe for motor cooling, wherein the flow impeller is in the form of a screw.
According to claim 1,
Internal heat conduction fins are formed to protrude inward on the inner wall of the heat pipe body forming the condensation portion, and the internal heat conduction fins are formed continuously in a spiral shape, so that when the heat pipe is mounted on the motor rotation shaft of the motor and rotated, the condensation occurs. A heat pipe for motor cooling, characterized in that it forces a negative liquid working fluid to flow toward the evaporation unit.
According to claim 3,
A heat pipe for motor cooling, wherein the flow impeller is fixed to the inside of a pipe-shaped coupling tube, and the outer peripheral surface of the coupling tube is fixed to the internal heat transfer fin.
According to claim 4,
External heat transfer fins are formed to protrude outward on the outer wall of the heat pipe body forming the condensation unit, and the external heat transfer fins are formed continuously in a spiral shape so that when the heat pipe is mounted on the motor rotation shaft of the motor and rotated, the heat pipe A heat pipe for motor cooling, characterized in that it forcibly blows gas outside the body.
A motor cooled by a heat pipe, characterized in that the motor cooling heat pipe of any one of claims 1 to 5 is mounted on the motor rotation shaft.