WO2016084900A1

WO2016084900A1 - Heat pipe, and cooling mechanism for rotating machine

Info

Publication number: WO2016084900A1
Application number: PCT/JP2015/083247
Authority: WO
Inventors: 望月　正孝; 横山　雄一; ランディープシン
Original assignee: 株式会社フジクラ
Priority date: 2014-11-28
Filing date: 2015-11-26
Publication date: 2016-06-02
Also published as: JP2016102616A

Abstract

A heat pipe provided with a tubular container having a working fluid in the interior and capable of rotating about a central axis that extends in the longitudinal direction. The container has a first end and a second end, which are the two ends in the longitudinal direction, and, in sequence in the longitudinal direction from the second end to the first end: a heat dissipation part including the second end, the inside diameter of at least a part of the container increasing in the direction from the second end to the first end, and the heat dissipation part being configured so as to release heat to the exterior; a heat insulating part adjacent to the heat dissipation part; and a heat reception part adjacent to the heat insulating part, the heat reception part being configured so as to receive heat from the exterior.

Description

Heat pipe and rotating machine cooling mechanism

The present invention relates to a heat pipe and a cooling mechanism of a rotary machine using the heat pipe, and more particularly to an internal structure of the heat pipe.
This application claims priority based on Japanese Patent Application No. 2014-241347 filed in Japan on November 28, 2014, the contents of which are incorporated herein by reference.

In recent years, the electrification of automobiles has progressed, and electric cars and fuel cell cars are being put into practical use. These vehicles require a drive motor. In a motor that rotates at high speed, it is important to cool the rotor that generates heat.

Patent Document 1 discloses an in-wheel motor for a vehicle including a heat pipe. The rotation of the motor is transmitted to a shaft connected to the wheel via a reduction gear in the wheel casing. The shaft has a through hole extending along the longitudinal direction. A part of the through hole is a flow path for cooling oil, and a straight tubular heat pipe is inserted in the other part. One end of the heat pipe is exposed to the outside of the wheel. The cooling oil circulates between the heat generating portion of the motor and the through hole by the centrifugal force generated by the rotation of the wheel and the action of the oil pump. The heat generated by the motor is transmitted to the heat pipe and finally dissipated to the outside of the wheel.

Japanese Unexamined Patent Publication No. 2009-190578

In the heat pipe, the working fluid sealed inside evaporates in the heat receiving part and condenses in the heat radiating part, so that heat is transferred. In the heat pipe described in Patent Document 1, the working fluid evaporates in the heat receiving portion in contact with the cooling oil, and the working fluid condenses in the heat radiating portion exposed to the outside of the wheel. In the heat radiating part, condensation occurs in a state where the inner wall of the hollow part of the heat pipe is covered with the liquid film of the working fluid (such condensation is called film-like condensation). In the film condensation, it is known that the liquid film of the working fluid becomes a thermal resistance, so that the thicker the liquid film of the working fluid, the higher the thermal resistance and the lower the thermal conductivity. Therefore, in order to improve the heat transfer performance of the heat pipe, it is important to prevent the working fluid liquid film from becoming thick in the heat radiating section.

This invention is made in view of the above, and provides the heat pipe which can suppress that the liquid film of a working fluid becomes thick in a thermal radiation part.

A first aspect of the present invention is a heat pipe, and includes a tubular container that is rotatable around a central axis extending in a longitudinal direction and has a working fluid therein. The container includes a first end and a second end that are both ends in the longitudinal direction, and a second end in order in the longitudinal direction from the second end to the first end, and the container as it goes from the second end to the first end. A heat-radiating part configured to increase the internal diameter of at least a part of the heat-dissipating element and to release heat to the outside; a heat-insulating part adjacent to the heat-dissipating part; And having.

The heat pipe of the first aspect is a so-called rotary heat pipe. The wall surface of at least a part of the heat radiating portion of the hollow portion of the tubular container is inclined with respect to the central axis so as to move away from the central axis toward the first end. Receives a force toward the first end due to the centrifugal force in the direction away from the central axis. As a result, the condensed working fluid is easily removed from the heat radiating portion, and the liquid film in the heat radiating portion can be prevented from becoming thick. Therefore, the thermal conductivity in the heat radiating portion is improved, and the heat transfer performance of the heat pipe is improved.

In the second aspect of the present invention, in the heat pipe of the first aspect, the inner wall surface of the heat receiving portion extends in parallel with the central axis.

According to a third aspect of the present invention, in the heat pipe of the first or second aspect, the inner wall surface of at least a part of the heat radiating portion is inclined at an angle of 1 degree to 3 degrees with respect to the central axis.

According to a fourth aspect of the present invention, in the heat pipe according to any one of the first to third aspects, a wick is provided on an inner wall surface parallel to the central axis in the container.

According to a fifth aspect of the present invention, in the heat pipe of the fourth aspect, the wick has a sintered body of copper powder.

According to a sixth aspect of the present invention, there is provided a cooling mechanism for a rotary machine, the heat pipe according to any one of the first to fifth aspects, the heat pipe being accommodated or integrally formed with the heat pipe, and a central axis. A shaft that can rotate with a heat pipe around it, a water cooling jacket that covers the shaft with a heat radiating part and circulates the cooling water inside, and is fixed to either the water cooling jacket or the shaft inside the water cooling jacket, around the central axis And a plate member extending in a spiral shape.

According to a seventh aspect of the present invention, there is provided a cooling mechanism for a rotary machine, wherein the heat pipe according to any one of the first to fifth aspects and the heat pipe are accommodated or integrally formed with the heat pipe. A shaft that can rotate with the heat pipe, and a fin that is fixed to the outer wall surface of the shaft at the heat radiating portion and includes a plurality of depressions.

According to the cooling mechanism for a rotating machine of the above aspect, it is possible to provide a cooling mechanism for a rotating machine that has a heat pipe with improved heat transfer performance and that can further utilize the performance of the heat pipe. it can.

According to an eighth aspect of the present invention, in the cooling mechanism for a rotary machine according to the sixth or seventh aspect, the shaft is fitted to the main shaft of a driving motor of the vehicle or is integrally formed with the main shaft.

According to the above aspect of the present invention, it is possible to provide a heat pipe that can prevent the liquid film of the working fluid from becoming thicker in the heat radiating portion and a cooling mechanism for a rotary machine including such a heat pipe.

It is a schematic sectional drawing of the cooling mechanism of the motor using the heat pipe which concerns on 1st Embodiment. It is a schematic sectional drawing of the heat pipe shown in FIG. FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A. It is a schematic sectional drawing which shows the modification of a heat pipe. It is a schematic sectional drawing which shows the other modification of a heat pipe. It is a schematic sectional drawing which expands and shows the vicinity of the thermal radiation part of the heat pipe shown in FIG. It is a schematic diagram which shows the heat pipe of this embodiment. It is a schematic diagram which shows the heat pipe of a comparative example. It is a schematic sectional drawing of the cooling mechanism of the motor using the heat pipe which concerns on 2nd Embodiment. FIG. 6B is a side view taken along line BB shown in FIG. 6A. It is an enlarged view of the A section shown in FIG. 6B.

Hereinafter, embodiments of the heat pipe of the present invention will be described with reference to the drawings. A heat pipe according to an embodiment of the present invention is fitted to a shaft and rotates together with the shaft. The present invention is not limited to the motor described in the following embodiments, and can be applied to shafts of rotating equipment such as engines, turbines, compressors, and pumps. The heat pipe can be formed integrally with the shaft, and the shaft can be formed integrally with the main shaft of the drive motor. Although the shaft of the present embodiment extends substantially horizontally, the extending direction of the shaft is not limited, and may extend, for example, in the vertical direction.

FIG. 1 is a schematic cross-sectional view showing a heat pipe according to a first embodiment fitted to a motor shaft. 2A and 2B are schematic cross-sectional views showing the heat pipe taken out, FIG. 2A is a side cross-sectional view, and FIG. 2B is a cross-sectional view along the line AA in FIG. 2A. For example, the motor 1 is a motor for driving an electric vehicle or a fuel cell vehicle.
The motor 1 includes a stator 3 fixed to a casing 6 and a rotor 4 that can rotate with respect to the stator 3. The casing 6 is fixed to a vehicle body (not shown). A rotating magnetic field is generated by exciting a winding (not shown) of the stator 3, and the rotor 4 rotates around the central axis C in synchronization with the rotating magnetic field. A shaft 7 of the motor 1 is provided coaxially with the rotor 4. The shaft 7 is a main shaft of the motor 1 for driving the vehicle, is fitted to the rotor 4, and can rotate around the central axis C together with the rotor 4. The shaft 7 penetrates the opening 6a of the casing 6 and is connected to a vehicle axle, a wheel, and the like (not shown) via a transmission (not shown) as necessary. The shaft 7 is held by the bearing 5 at two locations in the longitudinal direction L of the rotor 4. In the present specification, a direction parallel to the central axis C is referred to as a longitudinal direction L.

The shaft 7 has a through hole 7a, and a tubular heat pipe 12 is fitted into the through hole 7a. The heat pipe 12 includes a container 8, a wick 10 provided on the inner wall of the container 8, and a working fluid filled in the hollow portion 9 of the container 8. Although the wick 10 is provided in the heat pipe 12 of this embodiment, the wick 10 is not an essential element of the heat pipe of the present invention. The heat pipe of this invention should just have at least the container 8 and the working fluid with which the hollow part 9 of the container 8 was filled. The container 8 is fitted in the through hole 7 a of the shaft 7, has a central axis C extending in the longitudinal direction L common to the motor 1 and the shaft 7, and can rotate around the central axis C together with the shaft 7. The container 8 is inserted and fixed in the through hole 7 a of the shaft 7 through the silicon grease 11. The silicon grease 11 is applied in advance to the inner wall surface 7b of the through hole 7a, and fills the gap between the inner wall surface 7b of the through hole 7a and the container 8. The thickness of the silicon grease 11 is about 0.1 mm. The silicon grease 11 fixes the container 8 in the through hole 7 a and transfers heat from the shaft 7 to the container 8.

The heat of the motor 1 is mainly generated from the rotating rotor 4 (iron loss, coil loss, etc.). Some heat is generated from the stator 3, and heat is also generated by sliding from the bearing 5. In the case of a motor with an output of about 75 kW mounted on an electric vehicle, the maximum rotation speed reaches 12000 rpm, and the transmission is decelerated to about 1/10 and transmitted to the axle. Heat generated from the motor rotating at high speed is 350 to 500W. A part of this heat is released to the surrounding air, but there are many parts in the vicinity of a motor mounted on an electric vehicle or the like, and the cooling efficiency by air is not high. For this reason, much of the heat generated by the motor 1 is transmitted to the shaft 7.

The container 8 has a heat radiating part S1, a heat insulating part S2, and a heat receiving part S3 along the longitudinal direction L. A water cooling jacket 21 is attached to the end of the shaft 7 in order to enhance the heat dissipation effect of the heat dissipation portion S1. As will be described in detail later, cooling water circulates inside the water cooling jacket 21. The heat receiving portion S3 means a section including at least a portion facing the rotor 4 in the longitudinal direction L of the container 8, and the heat radiating portion S1 faces the internal space of the water cooling jacket 21, that is, the cooling water in the longitudinal direction L of the container 8. It means the section that is. A section between the heat receiving part S3 and the heat radiating part S1 in the longitudinal direction L of the container 8 is referred to as a heat insulating part S2.

The container 8 is made of a metal having high thermal conductivity, preferably copper, nickel or the like. The container 8 is formed to rotate coaxially with the shaft 7, and has a first end 8 e and a second end 8 f along the longitudinal direction L. The container 8 has a side wall 8a and

end surfaces

8b and 8c, and a sealed hollow portion 9 extending in the longitudinal direction L is formed between the side wall 8a and the end surfaces 8b and 8c. The hollow portion 9 faces the shaft 7 through the heat radiating portion S1, the heat insulating portion S2, and the heat receiving portion S3 of the container 8. The hollow portion 9 has the shape of a rotating body having a central axis C common to the motor 1 and the shaft 7, and the heat radiating portion S1 has a truncated cone shape in which the inner diameter 35 gradually decreases as the distance from the heat receiving portion S3 increases. Except S1, it has a cylindrical shape with a constant inner diameter 35 along the longitudinal direction L. The shape of the hollow portion 9 will be further described later. The hollow portion 9 is completely deaerated and then filled with a working fluid such as water or alcohol. In order to promote the evaporation of the working fluid, the hollow portion 9 may be decompressed.

In the longitudinal direction L of the container 8, a heat receiving part S3 that receives heat from the outside of the container 8, that is, through the shaft 7, from the motor 1 is located. That is, in the present embodiment, the heat receiving part S3 includes the first end 8e and is located between the first end 8e and the heat radiating part S1. In the longitudinal direction L of the container 8, a heat radiating portion S <b> 1 that radiates heat to the outside of the container 8 is configured. The heat radiation part S1 includes a second end 8f. In the present embodiment, the heat receiving portion S3 is located at the center portion in the longitudinal direction L of the container 8, but is not limited to this, and more generally, the heat radiating portion S1 from the second end 8f toward the first end 8e. The heat receiving part S3 should just be located in order.

In the hollow portion 9, the heat radiating portion S1 has an inner diameter 35 that increases toward the heat receiving portion S3, and the heat receiving portion S3 has a constant inner diameter 35. That is, the wall surface 9a of the hollow portion 9 (the inner wall surface of the container 8) is the heat radiating portion S1 with respect to the central axis C so as to move away from the central axis C as it goes from the second end 8f toward the first end 8e or the heat receiving portion S3. Is inclined. In the illustrated form, the wall surface 9a of the hollow portion 9 is inclined at a uniform inclination angle θ = 3 degrees with respect to the central axis C over the entire heat radiation portion S1. The inclination angle θ is preferably in the range of 1 degree to 3 degrees. The inclination angle θ is not constant in the heat radiating portion S1 and may be changed in the longitudinal direction L. The wall surface 9a of the hollow part 9 may be inclined only by a part of the heat radiating part S1, or may be inclined by a part or all of the heat insulating part S2 in addition to the heat radiating part S1. When the wall surface 9a of the hollow portion 9 is inclined at a part or all of the heat insulating portion S2, it is desirable that the inclined portion is continuous from the heat radiating portion S1. In the present embodiment, the wall surface 9a of the hollow portion 9 extends in parallel with the central axis C at the heat insulating portion S2 and the heat receiving portion S3. Although not shown, in another embodiment, the wall surface 9a of the hollow portion 9 extends in parallel with the central axis C at a part of the heat insulating portion S2 and the heat receiving portion S3. In still another embodiment, the wall surface 9a of the hollow portion 9 is only the heat receiving portion S3 and extends in parallel with the central axis C.

In the present embodiment, the outer wall surface 8d of the container 8 is inclined at the same inclination angle θ in accordance with the inclination of the wall surface 9a of the hollow portion 9. Therefore, the thickness of the side wall 8a of the container 8 is constant in the longitudinal direction L. The inner wall surface 7 b of the shaft 7 facing the container 8 is inclined at the same inclination angle θ as the wall surface 9 a of the hollow portion 9. The outer wall surface 7c of the shaft 7 has a constant diameter along the longitudinal direction L, and the thickness of the side wall 7d of the shaft 7 increases toward the second end 8f in the heat radiation portion S1. The thickness of the silicon grease 11 is constant over the entire length of the container 8, and the heat transfer characteristics of the silicon grease 11 are constant over the entire length of the container 8.

3A, the inner wall surface 7b and the outer wall surface 7c of the shaft 7 may be inclined in accordance with the inclination of the wall surface 9a of the hollow portion 9. The thickness of the side wall 7d of the shaft 7 is constant in the longitudinal direction L. Since the combined thickness of the shaft 7 and the container 8 is minimized, the cooling effect is enhanced. The thickness of the silicon grease 11 is constant over the entire length of the container 8.

As shown in FIG. 3B, the thickness of the side wall 8a of the container 8 may increase as it goes toward the second end 8f in the heat radiation portion S1. The side wall 7d of the shaft 7 has a constant inner diameter and the same outer diameter in the longitudinal direction L. Since the shaft 7 may be a simple hollow cylinder, it is easy to manufacture. Also in this case, the thickness of the silicon grease 11 is constant over the entire length of the container 8.

Referring again to FIG. 1, FIG. 2A, and FIG. 2B, a wick 10 is provided on the wall surface 9a of the hollow portion 9 that is parallel to the central axis C. In a preferred embodiment, the wick 10 is provided only on the wall surface parallel to the central axis C among the wall surfaces 9 a of the hollow portion 9. The wall surface parallel to the central axis C does not include the heat radiating part S1 and is located closer to the first end 8e than the heat radiating part S1, and is provided over the entire length of the heat insulating part S2 and the heat receiving part S3 in this embodiment. ing. As shown in FIG. 2B, the wick 10 is provided on the entire circumference of the wall surface 9 a of the hollow portion 9. The wick 10 holds and moves the liquid by capillary force.

Wick 10 is formed of a copper sintered body. In order to form the wick 10, first, a core (not shown) is inserted into the container 8. A region of the hollow portion 9 in which the wall surface 9a is inclined with respect to the center line C (hereinafter referred to as an inclined region 9b. In this embodiment, the region corresponding to the heat radiating portion S1) is completely filled with a core. In the inclined region 9b, there is no gap between the wall surface 9a and the core. In contrast, in the hollow portion 9, the wall surface 9a extends in parallel to the center line C (hereinafter referred to as a parallel region 9c. In the present embodiment, the region corresponds to the heat insulating portion S2 and the heat receiving portion S3). A gap is formed between the wall surface 9a and the core.

Next, the gap between the wall surface 9a of the hollow portion 9 and the core is filled with copper powder and sintered at a high temperature of about 1000 ° C. The copper powder is not filled in the inclined region 9b, but only in the parallel region 9c. When copper powder having a diameter of about 50 μm is filled, the porosity (a value obtained by dividing the total volume of the gaps between the powders by the volume of the gaps) is about 50%. The powders are fixed to each other by sintering, and a gap is secured between the powders. The copper powder is firmly fixed to the wall surface 9 a of the hollow portion 9. As a result, the porous wick 10 is formed. The wick 10 formed in this manner has sufficient stability against centrifugal force due to rotation. A copper wire can be filled in the gap instead of the copper powder. Similarly, when using a copper wire, the parallel region 9c between the wall surface 9a of the hollow portion 9 and the core is filled with the copper wire and sintered.

The wick 10 does not have to be formed over the entire length of the heat insulating portion S2 and the heat receiving portion S3, and is closer to the first end 8e than the heat radiating portion S1 of the container 8, and is parallel to the parallel region 9c (in this embodiment, the heat insulating portion S2 and It suffices if it is formed on at least a part of the heat receiving part S3). On the other hand, the wick 10 is not formed in the inclined region 9b (in this embodiment, the heat radiation portion S1). That is, the wall surface 9a of the hollow portion 9 is exposed in the inclined region 9b.

Next, the cooling mechanism of the heat pipe will be described with reference to FIG. One end of the shaft 7 is covered with a water cooling jacket 21, and the cooling water circulates inside the water cooling jacket 21. The cooling water cools the working fluid inside the container 8 through the shaft 7 and the container 8. The cooling water may be water or oil, but when the heat pipe 12 is used in an automobile, it is preferable to use a long life coolant (LLC) or a diluted solution obtained by diluting LLC with water in order to prevent the cooling water from freezing. .

The water cooling jacket 21 has an inlet 22 and an outlet 23 for cooling water, and the cooling water circulates inside the water cooling jacket 21 by a pump (not shown). In the longitudinal direction L of the heat pipe 12, the cooling water inlet 22 is provided at the upper part of the water cooling jacket 21 and the outlet 23 is provided at the lower part with respect to the central axis C, but the arrangement may be reversed. Between the water cooling jacket 21 and the shaft 7, there is provided a plate member 24 that is fixed to the water cooling jacket 21 and extends spirally around the central axis C. The plate member 24 forms a spiral flow path in the interior 21 a of the water cooling jacket 21, and increases the contact length and contact time with the cooling water shaft 7. The plate member 24 may be fixed to the shaft 7.

One end of the water cooling jacket 21 is sealed with a mechanical seal 25. The mechanical seal 25 is positioned by a sleeve 26 fitted to the shaft 7, a shoulder 21 b of the water cooling jacket 21, and a holding ring 27 that engages with the water cooling jacket 21. A seal 28 is sealed between the sleeve 26 and the shaft 7. The shaft 7 is supported by a bearing 29 and can rotate with respect to the water cooling jacket 21. The bearing 29 is positioned by the shoulder 21 c of the water cooling jacket 21 and the holding ring 30. The heat pipe 12, the shaft 7 and the water cooling jacket 21 constitute a cooling mechanism 2 of the rotating machine.

The operating principle of the heat pipe 12 is as follows. Referring to FIG. 1, heat H generated by a motor or the like is transmitted to the heat receiving portion S <b> 3 of the heat pipe 12 through the shaft 7. By this heat transfer, the working fluid enclosed in the hollow portion 9 of the heat pipe 12 evaporates. At this time, the working fluid absorbs latent heat (heat of vaporization) accompanying evaporation and increases internal energy. As a result, the heat pipe 12 efficiently absorbs heat generated by the motor 1 or the like. The evaporated working fluid diffuses and moves through the hollow portion 9 of the heat pipe 12, passes through the heat insulating portion S2, reaches the heat radiating portion S1, and is cooled there. This heat transfer condenses the evaporated working fluid. At this time, the working fluid releases latent heat (condensation heat) associated with condensation, and reduces internal energy.

Thus, the heat pipe 12 efficiently releases the heat generated by the motor 1 or the like. The released heat is transmitted to the cooling water circulating in the water cooling jacket 21 according to the principle of heat exchange, and is finally radiated to the atmosphere via a radiator (not shown). The working fluid condensed into a liquid phase adheres to the wall surface 9a of the hollow portion 9 of the heat pipe 12 by centrifugal force. In the heat dissipating part S1, the gas-phase working fluid is continuously condensed and a new liquid-phase working fluid continues to be generated, so that the liquid-phase working fluid is pressed against the wall surface 9a of the hollow part 9 by centrifugal force, It moves so that it may be extruded on the wall surface 9a of the part 9 toward the heat receiving part S3. Since the wick 10 is provided in the heat insulation part S2 and the heat receiving part S3, a driving force by a capillary force is applied, and the liquid-phase working fluid is transported along the wick 10 to the heat receiving part S3 and is evaporated again.

It is considered that the condensation of the working fluid in the heat radiation part S1 is a film-like condensation. In other words, the working fluid is condensed in a state where the liquid-phase working fluid adheres to the wall surface 9a of the hollow portion 9 that is the heat transfer surface. The film-like condensation has a lower thermal conductivity than the drop-like condensation in which vapor condensation occurs when the liquid is attached to the heat transfer surface in the form of droplets. In addition, it is known that the thermal conductivity of the film-like condensation has a correlation with the thickness of the liquid film, and that the thermal conductivity is improved as the thickness of the liquid film is smaller. Therefore, in order to improve the thermal conductivity of the film condensation, it is necessary to suppress the thickness of the liquid film of the working fluid as much as possible at the position where the condensation occurs.

FIG. 5A shows the heat pipe of this embodiment, and FIG. 5B shows the heat pipe of the comparative example. While the inner wall of the heat pipe 12 of the present embodiment is inclined at the heat radiating portion S1, the heat pipe 112 of the comparative example has a uniform cross section in the longitudinal direction L, and the heat radiating portion S1 is inclined. Not. In any example, the wick 10 is provided in the heat receiving part S3 and the heat insulating part S2.

In the present embodiment, the inner diameter 35 of the hollow portion 9 in the heat radiating portion S1 increases from the second end 8f toward the first end 8e. In other words, the wall surface 9a of the hollow portion 9 is inclined with respect to the central axis C so as to be away from the central axis C as it goes from the second end 8f to the first end 8e at the heat radiating portion S1. For this reason, a part of the centrifugal force acts on the liquid-phase working fluid attached to the wall surface 9a of the hollow portion 9 in the heat radiating portion S1 as a driving force toward the larger inner diameter 35, and the liquid toward the first end 8e. Phase fluid flow is facilitated.

Referring to FIG. 5A, the centrifugal force F is generated in a direction orthogonal to the central axis C, and the component force Fsinθ in the direction parallel to the wall surface 9a drives the liquid-phase working fluid toward the first end 8e along the wall surface 9a. To do. Accordingly, the liquid-phase working fluid continuously generated by film condensation in the heat radiating section S1 is continuously removed from the heat radiating section S1 by the centrifugal force component Fsinθ, and the liquid-phase working fluid existing in the heat radiating section S1. The thickness of the liquid film 31 is reduced and the thermal conductivity is improved. On the other hand, referring to FIG. 5B, since the wall surface 9a of the hollow portion 9 is parallel to the central axis C, the component force in the direction parallel to the wall surface 9a is zero. Therefore, as shown in the figure, the film of the working fluid 31 having a thick liquid phase as compared with FIG. 5A stays steadily, and the thermal conductivity deteriorates.

In the heat dissipating part S1, the wall surface 9a of the hollow part 9 is not provided with the wick 10 in order to further promote the flow of the liquid-phase working fluid toward the first end 8e (heat receiving part S3). Since the air gap inside the wick 10 extends in a random direction, it may act to inhibit driving by centrifugal force. That is, the wick 10 may prevent the smooth liquid phase working fluid from moving due to centrifugal force.

In the present embodiment, the wall surface 9a of the hollow portion 9 is exposed at the heat radiating portion S1, and the movement of the liquid-phase working fluid is hardly hindered. On the other hand, in the heat insulating part S2 and the heat receiving part S3, the wall surface 9a of the hollow part 9 is not inclined, and the driving force of the liquid-phase working fluid by the centrifugal force cannot be obtained. For this reason, the wick 10 is provided in the heat insulation part S2 and the heat receiving part S3, and the working fluid condensed into a liquid is conveyed in the longitudinal direction L by the capillary force. In order to further reduce the movement resistance of the liquid-phase working fluid in the heat radiating part S1, the wall surface 9a of the heat radiating part S1 may be subjected to a surface smoothing process such as polishing or Teflon (registered trademark) processing.

The fact that the wall surface 9a of the hollow portion 9 is not inclined by the heat insulating portion S2 and the heat receiving portion S3 is also effective for suppressing the maximum diameter of the heat pipe 12. For example, in FIG. 1, in one example, the total length L1 of the heat pipe 12 is 300 mm, the diameter d1 is 15.9 mm, and the length of the heat radiation part S1 is 10 to 50 mm. Assuming that the length of the heat radiation part S1 is 30 mm, the length of the other part is 270 mm. If there is an inclination of 3 degrees over the entire length of the heat pipe 12, it leads to an increase in diameter of 2 × 270 tan 3 ° = 28.3 mm. Even with a tilt of 1 degree, the diameter increases by 9.4 mm, which is an extremely large value compared to the diameter d1 of the heat pipe 12 = 15.9 mm. When the maximum diameter of the heat pipe 12 increases, the diameter of the shaft 7 that accommodates the heat pipe 12 also needs to be increased accordingly, which leads to an increase in the size of the motor 1. This has a significant impact on cost and vehicle design. Furthermore, if the wall surface 9a of the hollow portion 9 is greatly inclined at the heat receiving portion S3, the liquid-phase working fluid is biased too much in the longitudinal direction L, and the working fluid is not held in the entire heat receiving portion S3. Decreases. When the wall surface 9a of the hollow portion 9 extends parallel to the central axis C in the heat receiving portion S3, the liquid-phase working fluid is evenly distributed throughout the heat receiving portion S3, and a decrease in thermal conductivity can be prevented. .

6A to 6C show a second embodiment of the present invention. 6A is a schematic cross-sectional view of a heat pipe similar to that of the first embodiment, FIG. 6B is a side view taken along line BB of FIG. 6A, and FIG. 6C is an enlarged view of a portion A shown in FIG. 6B. Yes. Except for the configuration described below, the second embodiment of the present invention is the same as the first embodiment.
The heat pipe 12 of this embodiment employs an air cooling system. Specifically, a large number of fins 32 are fixed to the outer wall surface 7c of the shaft 7 in the heat radiation part S1. The fin 32 rotates together with the shaft 7 and dissipates heat transferred from the heat pipe 12 through the shaft 7 into the air.

The fin 32 has a large number of depressions 33. The recess 33 locally disturbs the air flow and promotes turbulent heat transfer on the surface of the fin 32. In turbulent heat transfer, heat transfer is promoted by the random mixing of air masses, and the heat transfer rate is greatly improved compared to laminar heat transfer. In laminar heat transfer, the air flow on the surface of the fin 32 is laminar, and heat transfer is less likely to occur, so the heat transfer rate is lower than in turbulent heat transfer. The heat pipe 12, the shaft 7, and the fin 32 constitute a cooling mechanism 34 of the rotating machine.

The air cooling method and the water cooling method may be used in combination, and although not shown, the heat pipe 12 and the shaft 7 are extended in the heat radiating portion S1, and the water cooling jacket 21 described in the first embodiment on the shaft 7 is used. The fins 32 described in the second embodiment can be arranged in series. In this case, in order to increase the heat transfer efficiency of the fin 32, it is desirable to provide the fin 32 at the end of the shaft 7 and the water cooling jacket 21 closer to the first end 8e than the fin 32.

DESCRIPTION OF SYMBOLS 1 Motor 2 Cooling mechanism of rotating machine 4 Rotor 7 Shaft 8 Container 9 Hollow part 9a Wall surface of hollow part 10 Wick 11 Silicon grease 12 Heat pipe 21 Water cooling jacket 24 Plate member 32 Fin 33 Indentation C Central axis L Longitudinal direction S1 Heat radiation part S2 Heat insulation part S3 Heat receiving part

Claims

Comprising a tubular container rotatable around a longitudinally extending central axis and having a working fluid therein,
A first end and a second end which are both ends in the longitudinal direction;
In the longitudinal direction from the second end toward the first end,
Including the second end, an inner diameter of at least a part of the container increases from the second end toward the first end, and a heat dissipating part configured to release heat to the outside;
A heat insulating part adjacent to the heat radiating part;
A heat receiving portion adjacent to the heat insulating portion and configured to receive heat from the outside;
Having a heat pipe.
The heat pipe according to claim 1, wherein an inner wall surface of the heat receiving portion extends in parallel with the central axis.
The heat pipe according to claim 1 or 2, wherein the inner wall surface of the at least part of the heat radiating portion is inclined at an angle of 1 degree to 3 degrees with respect to the central axis.
The heat pipe according to any one of claims 1 to 3, wherein in the container, a wick is provided on an inner wall surface parallel to the central axis.
The heat pipe according to claim 4, wherein the wick has a sintered body of copper powder.
The heat pipe according to any one of claims 1 to 5,
A shaft that accommodates the heat pipe or is integrally formed with the heat pipe and is rotatable around the central axis together with the heat pipe;
A water-cooling jacket that covers the shaft with the heat radiating portion and in which cooling water circulates;
A plate member fixed to one of the water cooling jacket and the shaft inside the water cooling jacket and extending spirally around the central axis;
Cooling mechanism for rotating machinery.
The heat pipe according to any one of claims 1 to 5,
A shaft that accommodates the heat pipe or is integrally formed with the heat pipe and is rotatable around the central axis together with the heat pipe;
A cooling mechanism for a rotary machine, comprising: a fin that is fixed to an outer wall surface of the shaft in the heat radiating portion and includes a plurality of depressions.
The cooling mechanism for a rotary machine according to claim 6 or 7, wherein the shaft is fitted to a main shaft of a driving motor of a vehicle or formed integrally with the main shaft.