WO2010117092A1

WO2010117092A1 - Loop heat pipe with nozzle and diffuser

Info

Publication number: WO2010117092A1
Application number: PCT/JP2010/056887
Authority: WO
Inventors: Shouichi Tanaka
Original assignee: Three Eye Co., Ltd.
Priority date: 2009-04-10
Filing date: 2010-04-12
Publication date: 2010-10-14
Also published as: WO2010117092A4

Abstract

An object of the present invention is to provide a loop heat pipe with plain structure and superior heat transmitting ability. The loop heat pipe with a steep slope portion and a gentle slope portion, which are arranged in turn to the flow direction. The steep slope portion constitutes a nozzle portion. The gentle slope portion constitutes a diffuser portion. A fluid resistance toward one side of the longitudinal direction of the fluid passage is larger than the other side of the longitudinal direction of the fluid passage. By boiling the liquid near the steep slope portion and the gentle portion, the liquid is forced to the one side. By mechanical vibration of the steep slope portion and the gentle portion, the liquid is forced to the one side.

Description

LOOP HEAT PIPE WITH NOZZLE AND DIFFUSER

BACK GROUND OF THE INVENTION [0001] 1. Field of the Invention

The present invention relates to a loop heat pipe with a nozzle and a diffuser.

2. Description of the Related Art

[0002] For example, a microprocessor, an inverter, a motor, an internal combustion engine and a secondary battery require strong cooling means. A known self-vibration type loop heat pipe moves liquid with bubbles by means of pressure vibration generated by boiling of the liquid. However, the flow quantity of the self-vibration type loop heat pipe is not enough. Because, the self-vibration type loop heat pipe needs a small diameter for dividing each bubble portion and each liquid portion.

[0003] U. S. Patent No. 4, 281, 709 and U. S. Patent No.3, 532, 159 describe a non-vibration type heat pipe with the coaxial double pipe structure. The heat pipe has a nozzle and a liquid diffuser. The nozzle reduces pressure of the steam flow from an evaporation portion to a condensation portion. The liquid diffuser changes a residual kinetic energy of the condensate at a condensation portion into pressure. A capillary phenomenon must be used to compensate for lack of pressure increase of the diffuser. [0004] U. S. Patent No. 3, 801, 843 discloses a heat pipe penetrating slots of a stator core of a motor axially. U. S. Patent No.693, 467B2 discloses a heat pipe penetrating axially near slot opening between two teeth which are adjacent one another.

SUMMARY OF THE INVENTION

[0005] An object of the present invention is to provide a loop heat pipe with plain structure and superior heat transmitting ability. [0006] The loop heat pipe of the present invention has a closed-loop-shaped fluid passage in which the fluid flows toward one direction. The loop heat pipe has a heat-radiating portion, a going pipe, a heat-absorbing portion, and a return pipe. The fluid in the heat-absorbing portion is heated. The fluid in the heat-radiating portion is radiated. The going pipe moves a fluid from the heat-absorbing portion to the heat-radiating portion. The return pipe returns a fluid from the heat-radiating portion to the heat-absorbing portion.

[0007] The loop heat pipe of the present invention has at least one pair of the steep slope portion and the gentle slope portion in turn in a flow direction. The cross section of the steep slope portion decreases toward the flow direction. Therefore, the steep slope portion constitutes a nozzle portion. The cross section of the gentle slope portion increases toward the flow direction. Therefore, the steep slope portion constitutes a diffuser portion. The nozzle portion has a larger changing ratio of the cross section than the nozzle portion. The changing ratio means a changing size of a width or a diameter of the fluid passage per a constant unit length of the fluid passage.

[0008] According to one aspect of the invention, the pair of the nozzle portion and the diffuser portion are vibrated mechanically. The fluid which is adjacent to the nozzle portion and the diffuser portion is forced toward one side of a longitudinal direction of the loop heat pipe. [0009] In a preferred embodiment, the loop heat pipe has a plurality of pairs of the steep slope portion and the gentle slope portion. In another preferred embodiment, the fluid consists of liquid. In another preferred embodiment, the fluid consists of liquid including vapor. In another preferred embodiment, the vibration source consists of an outer vibration sources vibrating a tube wall forcibly. In another preferred embodiment, the pair of the nozzle portion and the diffuser portion is vibrated toward the longitudinal direction of the pair. In another preferred embodiment, the pair of the nozzle portion and the diffuser portion is vibrated toward the width direction or the diameter direction of the pair. [0010] In another preferred embodiment, the heat-absorbing portion with the steep slope portion and the gentle slope portion is fixed directly or via a heat-transmitting member to a stator core of an alternative motor. In the other words, the stator core, which is a cooled object, is operated as the vibrating apparatus, too. The vibration type loop heat pipe can be constituted without the outer vibration apparatus, because it is available to use magnetostriction vibration of the stator core instead of the outer vibration apparatus. Furthermore, the magnetostriction vibration force of the stator core increases, when heat generation of the stator increases, because the heat generation of the stator is increased by increasing of the stator current. As a result, the quantity of heat transfer of the loop heat pipe is increased automatically, when the heat generation of the stator becomes large.

[0011] In another preferred embodiment, the heat-absorbing portion with the steep slope portion and the gentle slope portion is buried in a cylinder block of an internal combustion engine. The cylinder block can constitute the vibration apparatus, because the cylinder block vibrates largely. The above-explained vibration type loop heat pipe can be constituted without the outer vibration apparatus. The heat generation of the cylinder block increases when the vibration frequency becomes high or the strength of the vibration becomes strong. The heat transmitting can be increased automatically, when the heat generation of the cylinder block is increased. [0012] According to the suitable embodiment, the heat pipe consists of a steel pipe inserted by a cylinder block made from aluminum alloy. According to the suitable embodiment, the heat-absorbing portion consisting of the steel pipe is wound spirally around the cylinder boa. The spiral steel pipe improves a mechanical strength of the cylinder block. The cylinder block can become small shrinks.

[0013] According to another aspect of the invention, the liquid with micro bubbles is moved in the loop heat pipe with the steep slope portion and the gentle slope portion. The cross section of the steep slope portion making the nozzle portion is decreased toward the flow direction. The cross section of the gentle slope portion making the diffuser portion increase toward the flow direction. The changing ratio of the cross section of the steep portion is larger than the changing ratio of the cross section of the steep portion is larger.

[0014] The fluid dynamics teaches that the diffuser has a large pressure loss when the increasing ratio of the cross section is large, because the diffuser with the large increasing ratio of the cross section increases the swirl loss and the boundary layer detachment. As the result, the fluid resistance toward one side of the longitudinal direction of the pair of the nozzle and the diffuser is largely different from the fluid resistance toward the opposite side of the longitudinal direction of the pair of the nozzle and the diffuser. Self-excited vibration loop heat pipe can have stronger fluid speed by employing the nozzle-diffuser structure, after all. [0015] The known self-excited vibration method is explained simply, the liquid is forced toward the going pipe by the difference between the total bubble volume in the going pipe and the total bubble volume in the return pipe. The explosion force of the micro bubble is transmitted to all direction. However, the liquid in the heat-absorbing portion moves toward the going pipe direction, because the mass of the liquid in the going pipe is smaller than the mass of the liquid in the return pipe. The equation of F=ma is well-known. In the other words, the

[0016] According to another aspect of the invention, the liquid in the heat-absorbing portion with the steep slope portion and the gentle slope portion is boiled. Micro bubbles generated in the boiling liquid surrounded by the steep slope portion and the gentle slope portion forces the liquid toward one side of the longitudinal direction of the heat-absorbing portion. [0017] In the other words, pressure waves from the micro bubbles reflect on inner surfaces of the steep slope portion and the gentle slope portion. An axial direction component of the pressure waves toward one side of the longitudinal direction of the heat-absorbing portion is stronger than a reverse direction component of the pressure waves toward an opposite side of the longitudinal direction of the heat-absorbing portion. The liquid is forced to the one side of the longitudinal direction of the heat-absorbing portion after all.

[0018] As the result, the pressure wave forcing the liquid toward one side of the longitudinal direction is made by difference of both slope angles between the steep slope portion and the gentle slope portion. Furthermore, the difference between the fluid resistance toward the one side and the other side promotes fluid movement. Furthermore, the micro bubble can be drives by the known self-excited vibration method.

[0019] In another preferred embodiment, the fluid passage is formed among metal plates laminated to the thickness direction. Peripheral portions of plural metal plates are joined each other. The cross section of the fluid passage is changed by changing of the width of the fluid passage to the width direction of the metal plates. As a result, a plate-shaped loop heat pipe can be easily formed.

[0020] In another preferred embodiment, the going pipe and the return pipe are adjacent one another to the width direction of the metal plates. Furthermore, the gentle slope portion of the going pipe is adjacent to the gentle slope portion of the return pipe to the width direction of the metal plates. As a result, the fluid passages can be formed with high densely. [0021] In another preferred embodiment, a semiconductor element is fixed on a head of a bolt made from copper material or aluminum material. The heat-absorbing portion of the plate-type heat pipe is fixed to a rod of the bolt. The heat of the semiconductor element is transmitted to the heat-absorbing portion of each plate-type loop heat pipe through the bolt. As a result, the heat of the semiconductor element can be transmitted to a plurality of plate-type loop heat pipe well.

[0022] In the preferred embodiment, the loop heat pipe has a solenoid valve with a soft magnetic core and a solenoid coil. The solenoid valve forms the magnetic field penetrating the liquid passage. The liquid in the fluid passage includes soft magnetic powder. For example, the soft magnetic powder consists of soft iron powder dispersed by surfactant. By supplying a current to the solenoid coil, the soft magnetic powder in the liquid is accumulated near the core of the solenoid valve. Flow control of the loop heat pipe becomes simple, because the accumulated soft iron powder restrains the fluid flow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic section view showing a pipe type loop heat pipe of the embodiment 1.

Figure 2 is a schematic vertical section view showing an indirect heat exchanger having a pipe type loop heat pipe of the embodiment 2.

Figure 3 is a schematic transverse section of the indirect heat exchanger shown in Figure 2.

Figure 4A is a schematic transverse section showing a plate type loop heat pipe of the embodiment 3.

Figure 4B is a side view of the loop heat pipe shown in Figure 4A.

Figure 5 is a schematic vertical section view showing a plate type loop heat pipe of the embodiment 4.

Figure 6 is a schematic vertical section view showing an indirect heat exchanger with a plate type loop heat pipe of the embodiment 5.

Figure 7 is a schematic illustration showing the placement of a loop-shaped fluid passage of the embodiment 6.

Figure 8 is a schematic vertical section view showing an indirect heat exchanger with a plate type loop heat pipe of the embodiment 7.

Figure 9 is an illustration showing semiconductor-element-cooling apparatus with a plate type heat pipe of the embodiment 8.

Figure 10 is an illustration showing a semiconductor-element-cooling apparatus with a plate type loop heat pipe of the embodiment 9.

Figure 11 is an illustration showing a semiconductor-element-cooling apparatus with a plate type loop heat pipe of the embodiment 10.

Figure 12 is a schematic view showing a drum type plate type loop heat pipe of the embodiment 11.

Figure 13 is a schematic plan view showing a plate type loop heat pipe of the embodiment 12.

Figure 14 is a schematic section view showing an evaporation portion of a plate type loop heat pipe of the embodiment 13.

Figure 15 is a schematic transverse section view showing the loop heat pipes of the embodiments 14 and 20.

Figure 16A is a schematic sectional view showing the loop-type heat pipe in the 15th embodiment (at the state of the right movement of the heat pipe).

Figure 16B is a schematic sectional view showing the loop-type heat pipe in the 15th embodiment (at the state of the left movement of the heat pipe).

Figure 16C is a schematic sectional view showing the loop-type heat pipe in the 15th embodiment (showing the average stream).

Figure 17 is a schematic vertical section view showing an engine with a loop heat pipe of the embodiment 16.

Figure 18 is schematic axial section view showing a motor with a loop heat pipe of the embodiment 17. Figure 19 is an enlarged radial section view showing near slots of the motor with a loop heat pipe of the embodiment 17.

Figure 20 is a partially enlarged axial cross-section view showing a coil end of a motor with a loop heat pipe of the embodiment 17.

Figure 21 is a schematic section view of a cooling apparatus with a loop heat pipe of the embodiment 18.

Figure 22 is a schematic section view showing a heat-absorbing portion of a loop heat pipe of the embodiment 19.

Figure 23A, 23B and 23C are section views of a loop heat pipe with a solenoid valve of the embodiment 20.

Figure 23A is a section view along an arrow line A-A.

Figure 23B is a section view along an arrow line B-B.

Figure 23C is a section view of the loop heat pipe shown in the right angle of the longitudinal direction.

PREFERED EMBODIMENT OF THE IVENTION [0024] (Embodiment 1)

Figure lisa schematic section view showing a pipe-shaped loop heat pipe. Fluid in a loop heat pipe 1 of which both ends are joined is vibrated by a vibration source explained later. A loop-shaped fluid passage IA is formed in the loop heat pipe 1. For example, liquid consisting of the water is sealed up to a copper loop heat pipe 1.

[0025] An evaporation portion 2, which is a heat-absorbing portion, consists of one end portion of the loop heat pipe 1. The outer surface of the evaporation portion 2 receives heat from an outer heat source. A condensation portion 3, which is a heat-radiating portion, consists of the other end portion of the loop pipe 1. The outer surface of the condensation portion 3 is cooled by air or water. [0026] A going pipe 4 connects an exit of evaporation portion 2 to an inlet of condensation portion 3. A return pipe 5 connects an exit of condensation portion 3 to an inlet of evaporation portion 2. Going pipe 4 can have larger cross section than a cross section of return pipe 5. The cross section means a cross section of the fluid passage in a right angle of the flow direction. [0027] Evaporation portion 2 vaporizes a liquid. Going pipe 4 spreads a fluid including steam to condensation portion 3. The steam condenses at condensation portion 3. Return pipe 5 returns a residual steam flow which did not condense at condensation portion 3 to evaporation region 2. The micro water drops condensed at condensation portion 3 returns to evaporation portion 2 with the steam flow.

[0028] Going pipe 4 has three pairs of a diffuser portion 7 and a nozzle portion 6 in turn. Return pipe 5 has three pairs of a diffuser portion 7 and a nozzle portion 6 in turn, too. Evaporation portion 2 or condensation portion 3 can have nozzle portion 6 and diffuser portion 7. The cross section of nozzle portion 6 decreases continually toward fluid-moving direction 8.

[0029] The cross section of diffuser portion 7 increases continually toward fluid-moving direction 8. A cross-section-changing rate 'kd' of diffuser portion 7 is smaller than a cross-section-changing rate 'kn' of nozzle portion 6. The cross-section-changing rate means the difference of cross section area per a certain length toward fluid-moving direction 8. [0030] It is preferable that the changing rate ' kn' is more than several times of the changing rate ' kd' . The decrease of the changing rate ' kd' reduces the detachment of the boundary layer from the inner surface of the conduit and reduces the swirl loss of the fluid.

[0031] Therefore, in the nozzle portion 6, the fluid resistance to the fluid-moving direction, which is shown by an arrow of figure 1, is largely smaller than the fluid resistance to the reverse direction. As a result, the fluid moves to the arrow direction shown in Figure 1. [0032] The loop heat pipe must keep the condensate at starting time. A good method is to arrange evaporation portion 2 downward than condensation portion 3. Evaporation portion 2 and condensation portion 3 can have nozzle portion 6 and diffuser portion 7. [0033] (Embodiment 2)

The embodiment 2 is explained referring to Figures 2 and 3. Figure 2 is a schematic vertical section view showing an indirect heat exchanger having a pipe type loop heat pipe explained with embodiment 1. Figure 3 is a schematic transverse section of the heat pipe. The indirect heat exchanger has a cylinder 13 in which hot fluid 11 and cold fluid 12 flow through separately. A separating wall 14 separates the fluid 11 and the fluid 12. Loop pipe 1 is formed in the shape of a spiral coil. [0034] Loop pipe 1 penetrates the separating wall 14 every semicircle. The both end of loop pipe 1 is connected through a return pipe arranged axially of cylinder 13. As a whole, loop pipe 1 is formed in the shape of a loop. It is preferable to fix plate-shaped metal fins to loop pipe 1. For example, the above indirect heat exchanger is employed as an intercooler or an EGR cooler. [0035] (Embodiment 3)

Embodiment 3 is explained with reference to Figures 4A and 4B. Figure 4A is a schematic transverse section view showing a plate-shaped loop heat pipe. Figure 4B is a side view of the heat pipe. The heat pipe has a flat shape as shown in Figure 1. Metal plate lamination body 21 is formed by joining penumbras after laminating five pieces of copper sheets. [0036] Loop-shaped fluid passage 21A is formed inside of metal plate lamination body 21. Loop-shaped fluid passage 21A has an evaporation portion 22, a condensation portion 23, a going pipe 24 and a return pipe 25. Metal plate lamination body 21 is formed by joining after laminating small copper sheets 29A and 29B and large-sized copper sheets 28. The small copper sheets 29A and 29B are illustrated with slanted lines. [0037] The loop-shaped fluid passage 21A is formed by knocking down small copper sheets 29A and 29B. Loop-shaped fluid passage 21A is sealed up by the large-sized copper sheets 28 which are adjacent to both sides of the small copper sheets in the thickness direction. Edge portions of large-sized copper sheets 28 constitute a cooling fin 28A. Fin 28A radiates the heat to a secondary fluid, for example air. [0038] (Embodiment 4)

Embodiment 4 is explained referring to Figure 5. Figure 5 is a schematic vertical section view showing a plate-shaped loop heat pipe. The heat pipe consists of two pieces of copper sheets 31 and 32. The copper sheets 31 and 32 consist of pressed flat plates having a half of the loop-shaped fluid passage. Copper sheet 31 consists of a semicircle magnum 311 and a flat plate portion 312. Copper sheet 32 consists of a semicircle magnum 321 and a flat plate portion 322. The flat plate portions 312 and 322 are joined. The loop-shaped fluid passage with the circular section consists of a pair of semicircle cylinders 311 and 321. Figure 5 shows the going pipe portion IB and the return pipe portion 1C of the loop-shaped fluid passages. Flat plate portions 312 and 322 constitute a heat transfer fins to transfer heat to the outer secondary fluid. [0039] (Embodiment 5)

Embodiment 5 is explained referring to Figure 6. Figure 6 is a schematic vertical section view showing an indirect heat exchanger. The indirect heat exchanger is manufactured by laminating evaporation portions 102 of many plate-shaped loop heat pipes 101. The indirect heat exchanger with a box-shaped case 100 cools hot gas G which is a secondary fluid. Figure 6 shows a cross section in a right angle direction of a flow direction of hot gas G flowing from a front end surface to a rear end surface of the case 100. 'H' shown in the Figure is the horizontal direction. 'V shown in the Figure is the vertical direction. Evaporation portions 102 of five plate-shaped loop heat pipes 101 are inserted in the case 100 horizontally from the right end wall of the case 100. Five plate-shaped loop heat pipes

101 are arranged away from a predetermined distance each other. Pipe portions 103 consist of five pieces of plates which have the going tube potion and the return pipe portion each.

[0040] Five pieces of pipe portions 103 connect the evaporation portion

102 and the condensation portion (not shown) each. Each fin 104 being a spacer plate is disposed in each space between two pieces of two evaporation portions 102 being adjacent one another in the vertical direction V. Fin 104 consists of a mountain-shaped sheet made of metal. Hot gas G flows through hot gas passages consisting of gaps between the evaporation portion 102 and fins 104. The heat of the hot gas is given to the evaporation portion 102 through the fin 104 or directly. The heat given to the evaporation portion 102 vaporizes condensate in the evaporation portion 102. The above heat exchanger has high heat movement performance and is compact. [0041] (Embodiment 6)

Embodiment 6 is explained referring to Figure 7. Figure 7 is a partial schematic view showing one plate-shaped loop heat pipe with large number of loops-shaped fluid passage 111 toward. Each fluid passage 111 is next to the aspect course of the plate each other. Figure 7 shows four fluid passages 111. Dividing walls 110 separates two fluid passages 111 adjacent one another. Two fluid passages 111 adjacent one another make each fluid flow into the opposite direction one another. The nozzle portion of one fluid passage 111 is adjacent to the nozzle portion of the other fluid passage 111. The heat pipe can divide two fluid passages 111 by a thin dividing wall. Therefore, this one heat pipe has large number of fluid passages 111. Each fluid passage 111 can constitute each loop being independent each other. Each fluid passage 111 can connect to series. [0042] (Embodiment 7)

Embodiment 7 is explained referring to Figure 8. Figure 8 is a schematic vertical section view showing an indirect heat exchanger having a case 100. The indirect heat exchanger has four plates-shaped loop heat pipes 101. Four heat pipes 101 are laminated to the V direction (the thickness direction) with a predetermined distance each other. The indirect heat exchanger cools hot gas G by fresh air flow AIR. In Figure 8, hot gas G and fresh air flow AIR flow toward the right angle direction of the paper. Four plate-shaped loop heat pipes 101 horizontally penetrate the dividing wall 105. The evaporation portions 102 are disposed in a hot gas passage which is in left side of the dividing wall 105. The condensation portions 104 are disposed in an air chamber which is in right side of the dividing wall 105. Fin 104 which is a spacer consists of sheet metals broken by de Yamagata. The heat exchanger changes heat well between the hot gas and the fresh air flow, which have different, pressure one another. [0043] (Embodiment 8)

Embodiment 8 is explained referring to Figure 9. Figure 9 shows a semiconductor-element-cooling apparatus having the laminated plate-shaped loop heat pipes. A semiconductor module 200 can changed to a semiconductor chip. A bolt-shaped heat sink 201 consists of a bolt-shaped heat sink 201. The heat sink 201 consists of a large head portion 202 and a rod portion 203 extending straightly. Semiconductor module 200 is fixed on top surface of the head portion 202.

[0044] Central portions of four heat pipes 104 have through-hole into which the rod portion penetrates each. The rod portion 203 penetrates heat pipes 104 and ring-shaped metal spacers 204 in turn. A nut 205 is attached on the rod portion 203 and pushes heat pipes 104 and metal spacers 204 toward the head portion 202. The heat of the semiconductor module 200 is transmitted to each loop heat pipe 104 through the bolt-shaped heat sink 201 or the metal spacer 204. Each penumbra of heat pipes 104 is cooled by the cooling air flow flowing in parallel with to heat pipe 104. [0045] (Embodiment 9)

Embodiment 9 is explained referring to figure 10. Figure 10 shows the semiconductor-element-cooling apparatus with laminating plate-shaped loop heat pipes such as Figure 9. But, metal spacers 204 shown in figure 9 are omitted. Each heat pipe 104 is bent in the corrugate shape to keep each passage of the cooling air flow between each heat pipe 104. Each heat pipe can be bent at the different position of each heat pipe 104. The cooling apparatus can keep the cooling air passages between heat pipes 104 without using metal spacers 204 shown in Figure 9. [0046] (Embodiment 10)

Embodiment 10 is explained referring to Figure 11. Figure 11 shows the semiconductor-element-cooling apparatus with a lamination type plate-shaped loop heat pipe. A semiconductor chip can be adopted instead of the semiconductor module 200. One heat pipe is joined to a back surface of the heat sink 300. The heat pipe consists of plate portions 301 and 302 arranged in turn. The plate portion 301 extends to the thickness direction. [0047] The plate portion 302 is joined on the back surface of the heat sink 300. The plate portion 301 is bent toward the right angle of the plate portion 302. Each plate portion 301 separates by a gap having an equal width to the plate portion 302 and disposed in parallel. The cooling air flow flows in parallel to the plate portion 301 in the gaps. Each plate portion 301 has a length L.

[0048] One end plate portion 301 in the longitudinal direction receives heat from heat sink 300 through plate portion 302. The heat is given to the cooling air flow after transmitting to the longitudinal direction of each plate portion 301. Each plate portion 301 has a loop-shaped fluid passage each. A portion which is near to the heat sink 300 of the plate portion 301 constitutes the evaporation portion. A far portion which is apart from the heat sink 300 of the plate portion 301 constitutes the condensation portion. This cooling apparatus with simple structure can cool small heating body well. [0049] (Embodiment 11)

Embodiment 11 is explained referring to Figure 12. Figure 12 shows one plate-shaped loop heat pipe. The both ends of the heat pipe consist of cylindrical drums wound spirally. A cooling air flow CA penetrates the right cylindrical drum axially. A hot gas flow penetrates the left cylindrical drum axially. The heat that the left cylindrical drum got from the gas flow is transmitted to the right cylindrical drum through a steam rich pipe portion.

[0050] The right cylindrical drum is cooled by the cooling air flow CA. The fluid cooled by the right cylindrical drum returns to the left cylindrical drum through a liquid rich pipe portion. The accommodation in a cylinder pipe becomes easy, because the heat-absorbing portion (the evaporation portion) and the heat-radiating portion (the condensation portion) have cylindrical drum shape. [0051] (Embodiment 12)

Embodiment 12 is explained referring to Figure 13. Figure 13 shows a loop heat pipe 21 formed in the shape of a plate. The heat pipe 21 is constituted by joining peripheral portions of three metal plates 20 piled up. The central metal plate 20 has two loop-shaped fluid passages 22 and 23. The fluid passages 22 and 23 are formed in the shape of a multiplex ring. This heat pipe 21 can have more fluid passages. [0052] (Embodiment 13)

Embodiment 13 is explained referring to Figure 14. Figure 14 is a section view of the evaporation portion of one plate-shaped loop heat pipe 400. Heat pipe 400 is formed by joining peripheral portions of two metal plates 401 and 402. The mountain-shaped metal sheet 403 is accommodated between two metal plates 401 and 402. A flat surface of the metal sheet 403 is set in parallel with the flow. The metal sheet 403 consists of a no woven fabric consisting of the metal fiber capable to keep the condensate by a capillary phenomenon.

[0053] (Embodiment 14)

Embodiment 14 is explained referring to Figure 15. Figure 15 shows one plate-shaped loop heat pipe 21. The heat pipe 21 consists of two metal plates of which peripheral portions are joined one another. A loop-shaped pipe portion 21A including the nozzle portion 6 and the diffuser portion 7 is formed by the pressed two metal plates. In other words, loop-shaped fluid passage 21A including the nozzle portion 6 and the diffuser portion 7 is formed by piling up a pair of concave portions of the two metal plate. [0054] Nozzle portion 6 and diffuser portion 7 are formed in turn toward the longitudinal direction of the loop-shaped pipe. Heat pipe 21 is vibrated forcibly by outer vibration source (not shown). In other words, the heat pipe 21 is vibrated to a width direction of a long-plate-shaped loop heat pipe 21.

[0055] The nozzle portion 6 of the heat pipe 21 has an inner wall being a steep slope portion 60. The steep slope portion 60 is slanted for the longitudinal direction of the loop heat pipe 21. The diffuser portion 7 has an inner wall being a gentle slope portion 70. The gentle slope portion 70 is slanted for longitudinal direction of the heat pipe 21. The steep slope portion 60 has bigger skew angle than the gentle slope portion 70. [0056] The steep slope portion 60 of the nozzle portion 6 and the gentle slope portion 70 of the diffuser portion 7 makes a round trip by the vibration to the width direction (the X direction) of the heat pipe 21. The dotted line of Figure 15 shows a displacement state of the steep slope portion 60 and the gentle slope portion 70. [0057] A fluid coming into contact with the steep slope portion 60 and the gentle slope portion 70 is forced by changing a position of the steep slope portion 60 and the gentle slope portion 70 toward the arrow direction shown in Figure 15. As a result, fluid A in the diffuser portion 7 is forced to the right direction in Figure 15. Fluid B in the nozzle portion 6 is forced to the left direction in Figure 15. The mass of the fluid A which is adjacent to the diffuser portion 7 is bigger than the mass of the fluid B which is adjacent to the nozzle portion 6.

[0058] The fluid in the loop-shaped fluid passage 21A is forced to the right direction after all. As the fluid, the liquid or liquid-vapor flow with rich liquid is adopted. The forced vibration type heat pipe of this embodiment is called a width-direction-vibration type heat pipe, because the forced vibration of the width direction of the heat pipe is employed. [0059] (Embodiment 15)

Embodiment 15 is explained referring to Figure 16. Figure 16 shows a forced vibration type plate-shaped loop heat pipe. The structure of the heat pipe shown in Figure 16 is the same as the loop heat pipe 21 shown in Figure 15. However, the outer vibration source (not shown) gives vibration to the loop heat pipe 21 in the longitudinal direction Y. [0060] (a) shows a state that the loop heat pipe 21 is moved to the right side by the vibration. This is equal to a state that the loop heat pipe 21 stands still and the fluid moves to the left. As a result, the nozzle portion 6 becomes the diffuser and the diffuser portion 7 becomes the nozzle. The fluid resistance is big, because the nozzle portion 6 working as the diffuser has the steep slope portion 60. The moving speed of the fluid to the left direction is small after all.

[0061] (b) shows a state that the loop heat pipe 21 is moved to the left side by the vibration. This is equal to a state that the loop heat pipe 21 stands still and the fluid moves to the right. As a result, the nozzle portion 6 becomes the nozzle and the diffuser portion 7 becomes the diffuser. The fluid loss is small, because the diffuser portion 7 working as the diffuser has the gentle slope portion 70. The nozzle portion 6 has the steep slope portion 60, but the fluid loss of the nozzle is very small. The moving speed of the fluid to the right direction is big after all. [0062] (c) shows a state that the heat pipe is vibrated at high speed to the direction Y. In other words, the movement of (a) and the movement (b) are carried out in turn. The fluid moves to the right direction strongly for a movement period (b) . By the inertia of the fluid, the fluid moves to the right direction for a movement period (a).

[0063] The forced vibration type heat pipe of this embodiment is called a longitudinal-direction-vibration-type heat pipe, because the forced vibration to the longitudinal direction is adopted. The liquid flow or the liquid-vapor flow with rich liquid is employed as the liquid in the heat pipe. The above-mentioned forced vibration to the width direction or the longitudinal direction can be employed for the embodiments 1-13. The width-direction forced vibration and the longitudinal-direction forced vibration can be given heat pipe 21 at the same time. [0064] (Embodiment 16)

Embodiment 16 is explained referring to Figure 17. Figure 17 is a schematic vertical section view of an engine 600. A cylinder block 601 is made from aluminum. 602 is a cylinder head. 603 is a piston. 604 is the evaporation portion of the loop heat pipe (the heat absorption portion). 605 is the going pipe. 606 is the condensation portion (the heat-radiating portion). 607 is the return pipe.

[0065] The steep slope portion 60 and the gentle slope portion 70 shown in Figures 15-16 are disposed at the evaporation portion 604 wound spirally. The vibration of the cylinder block 601 is transmitted to the steep slope portion 60 and the gentle portion 70 well. The evaporation portion 604 formed of a steel tube is formed in the shape of a coil. Evaporation portion 604 is buried to cylinder block 601 made from aluminum alloy. Evaporation portion 604 surrounds the cylinder boa.

[0066] Condensation portion 606 as so-called the radiator is disposed at a place where a wind of the running vehicle comes into contact with. The inner surface of the cylinder boa is cooled well with the evaporation portion 604, because the coil-shaped evaporation portion 604 is disposed near the cylinder boa. The explosive force in the cylinder boa forces the cylinder block 601 radial outward. The strength of the cylinder block 601 increases, because the coil-shaped evaporation portion 604 surrounding the cylinder boa takes this explosive force. As a result, the weight and the volume of the cylinder block 601 can be reduced.

[0067] The conventional water-cooled engine has large cooling water pore near the cylinder boa. The cooling water pore reduces the strength of the cylinder block 601. This problem is solved by the coil-shaped evaporation portion 604 of the embodiment. For example, the cylinder block of this embodiment can reduce the volume and the weight of the cylinder block 601 of a diesel engine producing big explosive force. Furthermore, the miniaturization of the engine room and improvement of the mileage are enabled, and the abbreviation of the coolant pump is enabled, too. [0068] The operation of the forced vibration type heat pipe of this embodiment is explained below. The cylinder block 601 is strongly vibrated by combustion (explosion) in the cylinder boa. Vibrating cylinder block 601 lets the evaporation portion 604 of the loop heat pipe strongly vibrates to the longitudinal direction or the width direction (the diameter direction). Cylinder block 601 which is a cooling object constitutes the vibration source to let the evaporation portion of the forced vibration type loop heat pipe vibrate. [0069] In other words, the loop heat pipe moves internal liquid flow by the principle of a width direction vibration type loop heat pipe explained with the embodiment 14 or the embodiment 15. The reduction in cost is enabled, because this heat pipe does not need independent vibration source. Generally, the cooling necessity of the cylinder block increases, when the explosive power is big and when the engine rotates at high speed. A quantity of the fluid movement, namely the heat-transporting volume of the heat pipe increases, when the explosive power is big and when the engine rotates at high speed.

[0070] In other words, this heat pipe can increase quantity of heat movement in accordance with the increase of the heat radiation load automatically. The cylinder block can have the conventional coolant water pore other than the heat pipe mentioned above. The condensation portion (heat-radiating portion) of the heat pipe can adhere on a vehicle body easily. As a result, the heat of the engine is radiated through the vehicle body. [0071] (Embodiment 17)

Embodiment 17 is explained referring to Figure 18. Figure 18 is an axial section view of a motor. A frame 700 of an inner rotor type motor is a metal supporting member. 701 is a stator core. 702 is a stator winding. 703 is a rotor. 704 is an axis. 705 is a bearing. 710 is an above-explained loop heat pipe of the forced vibration type. Heat pipe 710 is a plate-shaped heat pipe. 711 is the evaporation portion being the heat absorption portion. 712 is the condensation portion being the heat-radiating portion. 713 are the going pipe and the return pipe.

[0072] Heat pipe 710 is formed by joining peripheral portions of two metal plates. The loop-shaped fluid passage is formed between the two metal plates. A predetermined volume of fluid, for example water, is enclosed in the fluid passage. The structure and the operation of the heat pipe of the forced vibration type is the same as above-explained embodiments 14 and 15. [0073] Each of heat pipes 710 penetrates each of slots of stator core 701 of the inner rotor type motor axially. A main surface of the evaporation portion 711 of heat pipe 710 adheres on a bottom surface of the slot which is located at the most outside in the radial direction. The both ends of heat pipe 710, is bended to the radial outward after projecting out of the slot. The bending is comparatively easy, because the bending is done toward the thickness direction of heat pipe 710. Furthermore, the bended both end portions of the heat pipe 710 adhere to an inner peripherary of the frame 700.

[0074] These both ends constitute the condensation portions 712. Good heat-transmitting member consisting of electrical insulator is disposed between the condensation portion 712 and the inner peripherary of the frame 700. The inner peripherary of the frame 700 has a flat portion for adhering on the plate-shaped condensation portion 712. The plate-shaped condensation portion 712 can have a partial-cylinder-shape for adhering on a cylindrical inner peripherary of frame 700.

[0075] Operation of the heat pipe is explained below. Heat pipe 10 is the forced vibration type heat pipe 710 explained in the embodiments 14-15 shown in Figures 15-16. The stator core 701 of the alternative motor vibrates by changing of the alternative magnetic flux because of the magnetostriction of the stator core. The vibration direction is mainly the diameter direction or the circumferential direction. In other words, the stator core 701, which is cooled, serves as the vibration source for vibrating the evaporation portion 711 of the forced vibration type heat pipe. [0076] Evaporation portion 711 has the steep slope portion (the nozzle portion) and the gentle slope portion (the diffuser portion), which are already explained. Reduction in cost can be realized, because the outer vibration apparatus is not required. The iron loss of stator core 701 of the alternative motor increases at the high rotating speed. The quantity of heat movement of the loop heat pipe 710 also increases automatically, because the vibration of stator core 701 increases at the high rotating speed.

[0077] Further detailed structure of the heat pipe 710 is explained referring to Figure 19. Figure 19 is a schematic radial section view showing the slot portion of the stator core. Evaporation portion 711 of the plate-shaped loop heat pipe 710 has a Oshaped cross section. The evaporation 711 mostly covers all surface of stator core 701 faced to the slot S. A bottom portion 711A of the evaporation portion 711 covers the bottom surface of the slot S.

[0078] Side surface portions 71 IB and 711C of the evaporation portion 711 cover up sides of the tooth of the stator core 701. A top portion 71 ID of the evaporation portions 711 and 711E adhere to brim portions of the tooth narrowing an opening of the slot S. For example, the heat pipe 710 has thickness of 1 - 2 mm. An electrically insulating layer covers on the outer surface of the evaporation portion 711. Heat pipe 710 serves as an insulator sheet protecting the stator winding 702.

[0079] Figure 20 is a schematic axial section view showing a coil end of stator winding 702. The going and return pipe 713 of heat pipe 710 are extending toward radial outward and adhere on one end surface of the stator core 701. Heat pipe 710 penetrates an aperture 714 of the frame 700, and it is extended in the outside of the frame 700. Heat pipe 710 reaches the condensation portion (it is not illustrated) fixed on an outer peripherary of the frame 700. The condensation portion of heat pipe 710 adheres to the outer surface of the frame 700.

[0080] The condensation portion of heat pipe 710 is cooled by fresh air flow or cooling liquid or the frame 700 well. The frame 700 is vibrated by the stator core 701. Accordingly, the whole of heat pipe 710 is strongly vibrated by the stator core 701 and the frame 700. As a result, the fluid transportation of the heat pipe 710 is improved. [0081] (Embodiment 18)

Embodiment 18 is explained referring to Figure 21. Figure 21 is a schematic section view showing a cooling device 9 for radiating an electrical apparatus 8. In Figure 21, the heat pipes are cut in the thickness direction of the heat pipes. The electric apparatus 8 consists of a three-phase inverter for a vehicle. The electric apparatus 8 consists of six power-switching modules 81-86 connected to bus bars (not shown). Each of the power-switching modules 81-86 consists of a card type module of which both main surfaces have contacting electrodes each.

[0082] The card module has two heat radiation plates, which combine the electrode plates. The heat radiation plates are disposed in parallel between power transistors. Two heat radiation plates are exposed on two main surfaces of the card module. The six card type power switching modules 81-86 consist of six arms of the three-phase inverter. The electric apparatus 8 is accommodated in a housing 80. Housing 80 is not done hatching in Figure 21. Six spacers 87 closed the opening of the housing 80. Spacer 87 is laminated toward a thickness direction of the power switching module plates 81-86.

[0083] Cooling device 9 has seven plate-shaped loop heat pipes 91-97 and a piezoelectric vibration apparatus 9A. The piezoelectric vibration apparatus 9A vibrates these loop heat pipes 91-97 to the thickness direction. Six spacers 98 are laminated to the thickness direction of the power switching module plates 81-86. Six spacers 98 are done hatching. The loop heat pipes 91-97 is shown with bold lines. Housing 80 is a box opening toward the right direction. The laminated power switching module plates 81-86 are accommodated in housing 80.

[0084] It is laminated with each seven inner end 99A of heat pipes 91-97 and each six power switching module plates 81-86 in turn. The heat pipes 91-97 and the module plates 81-86 are press-fitted between an upper plate 8OA and a lower plate 8OB of the housing 80. Inner ends 99A of seven plate-shaped loop heat pipes 91-97 are extended in the right side through intervals among six spacers 87. It is adhered with the upper plate 8OA, the spacers 87, the lower plate 8OB and the loop heat pipes 91-97. [0085] The heat pipes 91-97 projecting from the housing 80 have intermediate portions 99B and outer end portions 99C. Seven intermediate portions 99B are bended to a wave pattern in the thickness direction. Seven outer end portions 99C are extended from intermediate portion 90 more in the right side. The heat absorbing portion is built in seven inner end portions 99A each. Seven outer end portions 99C install the heat-radiating portion built-in each. Seven intermediate portions 99B have the going pipe and the return pipe built-in each. Each of the heat-absorbing portions, the going pipes, the heat-radiating portions and the return pipes constitute the heat pipe explained already.

[0086] The heat-radiating portion of the fluid passage disposed in an outer end 99C of the heat pipes 91-97 has at least one pair having the diffuser portion (the gentle slope portion) and the steep slope portion (the nozzle portion) , which are described already. The heat pipes 91-97 and six spacers 98 are laminated in turn. The six spacers 98 are adhered to heat pipes 91-97. The lower surface of outer end portion 99C of the heat pipe 97 is bonded to a piezoelectric vibration apparatus 9A. The lower surface of the piezoelectric vibration apparatus 9A is fixed to the housing 80 which is not shown.

[0087] Each of intermediate portions 99B and each of outer end portions 99C of the heat pipes 91-97 are separated by the spacers 87 and 98. A fan (not shown) generates cooling wind in parallel to the intermediate portions 99B and the outer end portions 99C. Operation of the above cooling apparatus 9 is explained below. A controller 9B drives the piezoelectric vibration apparatus 9A. The piezoelectric vibration apparatus 9A vibrates each outer end portions 99C of the heat pipes 91-97 and the spacers 98 upward and downward.

[0088] As the result, the liquid in the diffuser portion and the nozzle portion in outer end portions 99C flows through one direction. The liquid circulates through the heat absorption portions in the inner end portions

99A in the housing 80 via the intermediate portions 99B. The corrugate-shaped intermediate portions 99B absorb the vibration.

Furthermore, spacer 87 fixed to housing 80 prevents the vibration transmission from the intermediate portions 99B to the inner end portions

99A.

[0089] (Embodiment 19)

Embodiment 19 is explained referring to figure 22. This embodiment employs a self-vibration type loop heat pipe. The self-vibration type loop heat pipe is called self-excited vibration type loop heat pipe, too. Figure 22 shows the evaporation portion of the heat pipe 21. The evaporation portion of this heat pipe 21 has gentle slope portions 70 of the diffuser portion and the steep slope portions 60 of the nozzle portion 6. The water in the nozzle portion 6 and the diffuser portion 7 is boiled portionially by means by receiving heat. Figure 22 shows a state that one nucleus boiling occurs at one boiling point B.

[0090] The pressure wave is transmitted from the boiling point B spherically. The pressure wave reflects on inner wall surfaces of the steep slope portion 60 and the gentle slope portion 70 of the fluid conduit. Accordingly, a complicated pressure changing is given to the liquid in the diffuser portion 7 and the nozzle portion 6. By difference of the shape between the steep slope portion 60 and the gentle slope portion 70, the pressure wave toward one side of the longitudinal direction of the fluid passage becomes stronger than the other side of the longitudinal direction of the fluid passage. As a result, the fluid is forced to one direction of the fluid passage.

[0091] For example, the pressure wave occurred in boiling point B forces the inner liquid to right direction in Figure 22 by means of reflections of the pressure wave. When the local condensation occurs in the heat-radiating portion, the pressure wave occurs in a passage. As a result, the fluid in the condensation portion is forced to one direction. In other words, the pressure wave produced by boiling or condensation forces the liquid to one side of the longitudinal direction of the fluid passage. [0092] (Embodiment 20)

Embodiment 20 is explained with reference to Figure 23 A, 23B and 23C. Figure 23A is a section view along an arrow line A-A. Figure 23B is a section view along an arrow line B-B. Figure 23C is a section view along a width direction of the loop heat pipe. A feature of the embodiment is that the heat pipe with the forced vibration type or the self vibration type mentioned above has a valve 800 for controlling the fluid flow. The valve 800 can be disposed on the conventional loop heat pipe.

[0093] A plate-shaped loop heat pipe 1 has fluid passage IA. The liquid is sealed in the loop heat pipe 1. For example, the liquid is water in which soft iron powder and surfactant are mixed. Loop heat pipe 1 is made from consists of by the nonmagnetic metal pipes such as aluminum and copper and stainless steel or the titanium. Loop heat pipe 1 constitutes the evaporation portion 2, the condensation portion 3, the pipe portion 4 and the pipe portion 5 explained above.

[0094] The valve 800 is an electromagnetic valve disposed outside of the loop heat pipe 1. Valve 800 consists of a solenoid coil 802 wound on a C-shaped soft ferrite core 801. By supplying a DC current to the solenoid coil 802, a DC magnet field is generated through the core 801 and the loop heat pipe 1. As the result, the DC magnet field is excited in the loop heat pipe 1. The soft iron powder flows with the liquid when the current is not supplied to the solenoid coil 802. The soft iron powder accumulates near the core 802, when the current is supplied to the solenoid coil 802. Accordingly, the liquid flow is obstructed.

[0095] Accumulation of the soft iron powder increases in accordance to the current. The liquid flow is controlled by controlling the current of the solenoid coil 802. As a result, the heat movement of the loop heat pipe 1 is controlled. For example, the temperature of an engine is raised by increasing the current of the solenoid coil 802, when the engine is cold. [0096] The vibrated loop heat pipe can be made from magnetostriction metal. A winding is wound around the loop heat pipe.

As the result, the liquid in the loop heat pipe flow one side of the longitudinal direction, because the loop heat pipe vibrates with own magnetostriction. In other words, the loop heat pipe with the solenoid coil can serve as the vibration apparatus.

Claims

1. A loop heat pipe with a closed-loop-shaped fluid passage in which a predetermined volume of fluid flows toward one direction, the loop heat pipe has a heat-radiating portion, a going pipe, a heat-absorbing portion and a return pipe, the fluid heated in the heat-absorbing portion is moved to the heat-radiating portion through the going pipe and the fluid radiated in the heat-radiating portion is moved to the heat-absorbing portion through the return pipe: wherein the loop heat pipe has at least one pair of a steep slope portion and a gentle slope portion in turn in the flow direction; the cross section of the steep slope portion constituting a nozzle portion decreases toward the flow direction; the cross section of the gentle slope portion constituting a diffuser portion increases toward the flow direction; the nozzle portion has a larger changing ratio of the cross section than the nozzle portion; and the fluid being adjacent to the nozzle portion and the diffuser portion is forced toward one side of a longitudinal direction of the loop heat pipe by at least one of mechanical vibration of at least one pair of the nozzle portion and the diffuser portion and bubbles in the boiling liquid in the heat-absorbing portion.

2. The loop heat pipe according to claim 1, wherein the loop heat pipe has a plurality of pairs of the steep slope portion and the gentle slope portion.

3. The loop heat pipe according to claim 1, wherein the fluid consists of liquid.

4. The loop heat pipe according to claim 1, wherein the fluid consists of liquid including vapor.

5. The loop heat pipe according to claim 1, wherein the pair of the nozzle portion and the diffuser portion are vibrated toward the longitudinal direction of the pair.

6. The loop heat pipe according to claim 1, wherein the pair of the nozzle portion and the diffuser portion are vibrated toward at least one of a width direction and a diameter direction of the pair.

7. The loop heat pipe according to claim 1, wherein the heat-absorbing portion with the steep slope portion and the gentle slope portion is fixed directly or via a heat-transmitting member to a stator core of an alternative motor, which vibrates with magnetostriction of the stator core.

8. The loop heat pipe according to claim 7, wherein the heat-absorbing portion with the steep slope portion and the gentle slope portion is accommodated in a slot of the stator core.

9. The loop heat pipe according to claim 8, wherein both ends of the loop heat pipe are extending out of the slot.

10. The loop heat pipe according to claim 1, wherein the heat-absorbing portion with the steep slope portion and the gentle slope portion is buried in a cylinder block of an internal combustion engine and is vibrated with vibration of the cylinder block.

11. The loop heat pipe according to claim 10, wherein the heat-abs absorbing portion is made of the steel pipe wound around a cylinder boa of the cylinder block.

12. The loop heat pipe according to claim 1, wherein the fluid is moved by the bubbles', and the nozzle portion and the diffuser portion arranged to series toward the longitudinal direction accelerate the fluid flow.

13. The loop heat pipe according to claim 12, wherein the heat-absorbing portion has the steep slope portion and the gentle slope portion.

14. The loop heat pipe according to claim 1, wherein the fluid passage is formed among metal plates laminated to the thickness direction.

15. The loop heat pipe according to claim 14, wherein the cross section is changed by changing the width of the fluid passage.

16. The loop heat pipe according to claim 14, wherein the going pipe and the return pipe are adjacent one another to the width direction of the metal plates.

17. The loop heat pipe according to claim 14, wherein the loop heat pipes consisting of the metal plates each are absorbing heat of a semiconductor element through a bolt made from metal material; the semiconductor element is fixed on a head of the bolt; and the metal plates are inserted through by a rod of the bolt; and the metal plates are forced to the head by a nut.

18. The loop heat pipe according to claim 11, wherein the loop heat pipes has a solenoid valve with a soft magnetic core and a solenoid coil; the fluid consists of liquid including soft magnetic powder; and the soft magnetic powder in the liquid is accumulated near the core of the solenoid valve by supplying a current to the solenoid coil.