JP2017116151A - Cooling device, electronic equipment and electric vehicle mounting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device which secures lowering of cooling performance and operation stability especially at low calorific value time, in the case where heat quantity generated by a semiconductor element in an electronic circuit of electronic equipment and an electric vehicle varies from a low calorific value to a high calorific value, and which has achieved high cooling performance in a wide range to a high calorific value.SOLUTION: A vertical part of a heat radiation path 6 is constituted by a main path 6a and a sub path 6b. As a cross section of the sub path 6b is constituted to be smaller than a cross section of the main path 6a, lowering of cooling performance and operation stability during low calorific value time are secured by the sub path 6b mainly operating at the low calorific value time, and at high calorific value time, the main path 6a and the sub path 6b operate simultaneously. With this constitution, a cooling device has achieved high cooling performance in a wide range from the low calorific value to the high calorific value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cooling device, an electronic device equipped with the cooling device, and an electric vehicle.

  Conventionally, this type of cooling device is known to be mounted on a power conversion circuit of an electronic device or an electric vehicle. In an electric vehicle, an electric motor serving as a driving power source is switched by an inverter circuit that is a power conversion circuit. A plurality of semiconductor switching elements represented by power transistors are used in the inverter circuit, and a large current of several tens of amperes flows through each element. Therefore, great heat was generated and it was necessary to cool.

  Therefore, conventionally, as in Patent Document 1, for example, a heating element such as a semiconductor switching element is cooled by a loop heat pipe including a heating unit 101, a cooler 102, a rising pipe 103, and a lowering pipe 104. .

  Hereinafter, the loop heat pipe shown in Patent Document 1 will be described with reference to FIG.

  As shown in FIG. 8, the loop heat pipe includes a loop circuit 105 that includes an ascending pipe 103 and a descending pipe 104, a heat medium 106 that is a working fluid sealed in the loop circuit 105 under vacuum, and a loop circuit 105. And a heating unit 101 positioned below the riser pipe 103 and a heat medium in the loop circuit 105 interposed in the lower part in the loop circuit 105. And a check valve 107 for limiting the circulation direction of 106.

  Here, when heat is generated in the semiconductor switching element brought into contact with the heating unit 101, the generated heat is transmitted to the heating unit 101, and heat is applied to the heat medium 106 circulating in the heating unit 101 to be vaporized. The circulation direction is limited by the check valve 107, and the vaporized heat medium 106 rises up the ascending pipe 103 and is led to the cooler 102 to be cooled. Here, the heat applied by the heating unit 101 is released. The heat medium 106 that has released heat from the cooler 102 descends the downcomer 104 and circulates again to the heating unit 101 via the check valve 107.

JP 61-038396 A

  In such a conventional cooling device, the diameter of the rising pipe 103 needs to be increased as the amount of vaporization increases in accordance with the amount of vaporization of the generated heat medium 106. That is, the greater the amount of heat generated by the semiconductor switching element, the greater the amount of vaporization of the heat medium 106. Therefore, it is necessary to increase the diameter of the riser tube 103. On the other hand, the amount of heat generated by a semiconductor switching element is not always constant, and even if the same semiconductor switching element is used, the amount of generated heat varies depending on the operating state. Often less.

  In such a case, if the pipe diameter of the riser tube 103 is too large with respect to the heat generation amount, a phenomenon may occur in which the liquid-phase heat medium 106 flows backward to the lower side, that is, the heating unit 101 side in the middle of the riser pipe 103. In many cases, the heat medium 106 that has received heat by the heating unit 101 does not move smoothly to the cooler 102 side but stays in the heating unit 101, so that the temperature of the heating unit 101 rises, resulting in a decrease in cooling performance. Had.

  Therefore, the present invention solves the above-described conventional problems, and when the semiconductor switching element is activated, the heat medium 106 (working fluid) in the riser tube 103 (heat radiation path) flows downward to the heating unit 101 side. It is an object of the present invention to provide a rejection device that can smoothly circulate the working fluid from the heat receiving portion to the heat radiating portion even with a low calorific value at the time of startup, and consequently prevents a decrease in cooling performance. And

  In order to achieve this object, the cooling device of the present invention releases the heat of the working fluid from the heat receiving plate that transfers the heat from the heating element to the working fluid from the heat receiving plate that is in contact with the heating element. A heat dissipating part, a heat dissipating path connecting the heat receiving part and the heat dissipating part, and a feedback path, and the working fluid is transferred to the heat receiving part, the heat dissipating path, the heat dissipating part, the feedback path, and the heat receiving part. A cooling device that circulates heat and includes a backflow prevention valve in the return path, and the working fluid when a pressure upstream of the backflow prevention valve becomes higher than a pressure downstream of the backflow prevention valve Passes through the backflow prevention valve, the working fluid is supplied onto the heat receiving plate, a part of the supplied working fluid is vaporized, and the remaining working fluid is caused to expand from the inflow port to the inlet by volume expansion at that time. Diffused from the gap with the heat receiving plate to the outer periphery, The working fluid spreads and vaporizes as a thin film on the surface of the heat receiving plate, and the vertical portion of the heat dissipation path is composed of a main path and a sub-path, and the cross-sectional area of the sub-path is smaller than the cross-sectional area of the main path This achieves the intended purpose.

  According to the cooling device of the present invention, a heat receiving part that transmits heat from the heat generating element to the working fluid from a heat receiving plate that is in contact with the heat generating element, a heat radiating part that releases heat of the working fluid, and the heat receiving part. A heat dissipation path connecting the heat dissipation section and a return path are provided, and the working fluid is circulated to the heat receiving section, the heat dissipation path, the heat dissipation section, the return path, and the heat receiving section to move heat. A cooling device comprising a backflow prevention valve in the return path, and when the pressure upstream of the backflow prevention valve is higher than the pressure downstream of the backflow prevention valve, the working fluid passes through the backflow prevention valve. The working fluid is supplied onto the heat receiving plate, and a part of the supplied working fluid is vaporized, and the remaining working fluid is discharged from the gap between the inlet and the heat receiving plate due to volume expansion at that time. The working fluid is diffused to the surface of the heat receiving plate. As well as spread vaporized as a thin film, the vertical portion of the heat radiation path is constituted by the main path and the sub path, the cross-sectional area of the secondary path has a sectional area smaller than the configuration of the main path.

  This allows the working fluid to circulate smoothly from the heat-receiving part to the heat-dissipating part even when the heat generation path is low by dividing the heat-dissipating path into two main paths and sub-paths compared to a single heat-dissipating path. As a result, a decrease in cooling performance can be prevented.

  It is known as a capillary phenomenon that the surface tension of the liquid existing in the pipe increases as the cross-sectional area of the pipe decreases, and the force acts in the direction of pushing up the surface of the liquid. That is, by making the cross-sectional area of the sub-path smaller than the cross-sectional area of the main path, the surface tension of the working fluid in the sub-path increases and the force acts in the direction of pushing up the working fluid in the sub-path. The working fluid to the side can be easily transported from the main path. As a result, it is possible to smoothly circulate the working fluid from the heat receiving portion to the heat radiating portion even with a low calorific value at the time of startup, and as a result, it is possible to prevent the cooling performance from being lowered.

1 is a schematic diagram of an electric vehicle equipped with a cooling device according to a first embodiment of the present invention. (A) Schematic diagram of the cooling device, (b) A diagram showing a heat dissipation path in a state where the heat dissipation path of the cooling device is divided into a main route and a sub route. Schematic showing the pulsation phenomenon of the working fluid in the riser when starting the conventional cooling device (A) Graph showing the input heat amount in the conventional cooling device and the circulation flow rate of the working fluid circulating in the device, and (b) Graph showing the input heat amount and pressure fluctuation in the heating unit in the conventional cooling device. (A) A graph showing a comparison between the amount of heat input and the pressure fluctuation in the heating unit in the conventional and the cooling device of the present invention, (b) in the cross-sectional area ratio of the main path and the sub-path in the cooling device according to the first embodiment of the present invention. Graph showing maximum pressure at start-up (A) Schematic diagram of the cooling device according to the first embodiment of the present invention when the axis of the main path and the sub path provided in the main path is located concentrically, (b) Partition plate in the main path and the main path Schematic of the cooling device according to Embodiment 3 of the present invention in which the sub-path is configured by providing Schematic of the cooling device shown in the second embodiment of the present invention when a sub-path is provided so as to circumscribe the main path Schematic showing a conventional cooling device

  The cooling device according to claim 1 of the present invention includes a heat receiving part that transmits heat from the heat generating element to the working fluid from a heat receiving plate that is in contact with the heating element, a heat radiating part that releases heat of the working fluid, and A heat-dissipating path connecting the heat-receiving part and the heat-dissipating part and a return path, and circulating the working fluid to the heat-receiving part, the heat-dissipating path, the heat-dissipating part, the return-path, and the heat-receiving part. A cooling device that moves, wherein the return path includes a backflow prevention valve, and when the pressure upstream of the backflow prevention valve becomes higher than the pressure downstream of the backflow prevention valve, the working fluid is the backflow prevention valve. The working fluid is supplied onto the heat receiving plate, a part of the supplied working fluid is vaporized, and the remaining working fluid is removed by a gap between the inlet and the heat receiving plate due to volume expansion at that time. Diffused from the outer periphery to the surface of the heat receiving plate With dynamic fluid spreads vaporized as a thin film, the vertical portion of the heat radiation path is constituted by the main path and the sub path, the cross-sectional area of the secondary path has a sectional area smaller than the configuration of the main path.

  This allows the working fluid to circulate smoothly from the heat-receiving part to the heat-dissipating part even when the heat generation path is low by dividing the heat-dissipating path into two main paths and sub-paths compared to a single heat-dissipating path. As a result, a decrease in cooling performance can be prevented. It is known as a capillary phenomenon that the surface tension of the liquid existing in the pipe increases as the cross-sectional area of the pipe decreases, and the force acts in the direction of pushing up the surface of the liquid. That is, by making the cross-sectional area of the sub-path smaller than the cross-sectional area of the main path, the surface tension of the working fluid in the sub-path increases and the force acts in the direction of pushing up the working fluid in the sub-path. The working fluid to the side can be easily transported from the main path. As a result, it is possible to smoothly circulate the working fluid from the heat receiving portion to the heat radiating portion even with a low calorific value at the time of startup, and as a result, it is possible to prevent a decrease in cooling performance.

  The sub route may be inscribed in the main route. Thereby, it is possible to realize a good circulation of the working fluid at the start-up with a simple structure.

  The sub route may be positioned concentrically with the main route. Thereby, it is possible to realize a good circulation of the working fluid at the time of activation.

  Moreover, it is good also as a structure where the sub route built in the main route of the heat dissipation route circumscribes the main route. Thereby, it is possible to realize a good circulation of the working fluid at the time of activation.

  The area ratio A2 / A1 between the cross-sectional area A1 of the main path and the cross-sectional area A2 of the sub-path may be in the range of 0.1 to 0.5. Thereby, it is possible to realize a good circulation of the working fluid at the time of activation.

  Moreover, you may make it the structure set as the electronic device made into the structure provided with the cooling device of this invention. Thereby, at the time of starting of an electronic device, the effect | action that the circulation of the working fluid in a cooling device is stabilized and the fall of cooling performance can be suppressed can be acquired.

  Moreover, you may make it the electric vehicle provided with the structure provided with the cooling device of this invention. As a result, the electric vehicle has a configuration including a cooling device having an effect of stabilizing the circulation of the working fluid in the cooling device at the time of starting and suppressing a decrease in cooling performance, and as a result, at the time of starting the electric vehicle. The effect that operation stability can also be secured can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, an electric motor (not shown) that drives an axle (not shown) of the electric vehicle 1 is connected to an inverter circuit 2 that is a power conversion device arranged in the electric vehicle 1.

  The inverter circuit 2 supplies electric power to the electric motor, and includes a plurality of semiconductor switching elements 9 (FIG. 2). The semiconductor switching elements 9 generate heat during operation.

  For this reason, in order to cool this semiconductor switching element 9, the cooling device 3 which cools by circulating the working fluid 11 (FIG. 2) used as a heat medium is provided.

  Here, for example, water or ethanol is used as the working fluid 11.

  The cooling device 3 includes a heat receiving part 4 that transmits heat to the working fluid 11 and a heat radiating part 5 that releases the heat of the transmitted working fluid 11, and a heat medium is provided between the heat receiving part 4 and the heat radiating part 5. By providing the heat dissipation path 6 for circulating the working fluid and the return path 7, a circulation path for circulating the working fluid 11 through the heat receiving part 4, the heat dissipation path 6, the heat dissipation part 5, the return path 7, and the heat receiving part 4 is configured. doing.

  Furthermore, by providing the return path 7 with the backflow prevention valve 16 (FIG. 2), when the working fluid 11 is changed to a high-pressure gas phase state (water vapor in the case of water) in the heat receiving section 4, the return path 7 side is returned. Without reverse flow, in a mixed phase state with a liquid phase, the heat receiving part 4 passes through the heat dissipation path 6 to reach the heat dissipation part 5, and after radiating, all in the liquid phase state through the feedback path 7 to the heat receiving part 4 in one direction. It is supposed to circulate.

  The heat radiating part 5 is cooled and released heat by the outside air being blown from the blower 8.

  The heat released from the heat radiating unit 5 can also be used for heating the inside of the electric vehicle 1.

  From this, the cooling device 3 of this invention is explained in full detail using FIG.

  As shown in FIG. 2, the heat receiving unit 4 forms a heat receiving plate 10 that contacts the semiconductor switching element 9 and absorbs heat, and a heat receiving space 12 that covers the surface of the heat receiving plate 10 and evaporates the working fluid 11 that has flowed in. And a heat receiving plate cover 13.

  Further, the heat receiving plate cover 13 is provided with an inlet 14 for allowing the working fluid 11 to flow into the heat receiving space 12 from the return path 7 and an outlet 15 for discharging the working fluid 11 from the heat receiving space 12 to the heat dissipation path 6. .

  Further, the return path 7 is provided with a backflow prevention valve 16 in the vicinity of the inlet 14.

  The operation of the cooling device 3 having such a configuration will be described.

  In the above configuration, when the semiconductor switching element 9 of the inverter circuit 2 (FIG. 1) starts operation, electric power is supplied to the electric motor, and the electric vehicle 1 (FIG. 1) starts to move.

  At this time, a large amount of heat is generated due to a large current flowing through the semiconductor switching element 9.

  Here, the heat generated in the semiconductor switching element 9 is transmitted to the heat receiving plate 10. The heat transmitted to the heat receiving plate 10 instantly vaporizes the working fluid 11 supplied onto the heat receiving plate 10 in the heat receiving space 12 and changes a part of the working fluid 11 to a gas phase state. The working fluid 11 in a mixed phase of the gas phase and the liquid phase to which the vaporization latent heat and sensible heat are given circulates from the discharge port 15 to the heat radiation path 6 and flows into the heat radiation portion 5, is cooled by the heat radiation portion 5, and is All of the phase working fluid 11 is condensed to be in a liquid phase state, thereby releasing latent heat of condensation and sensible heat to the outside air.

  Subsequently, the working fluid 11 that has released the condensation latent heat and sensible heat circulates to the return path 7 and accumulates on the backflow prevention valve 16. The working fluid 11 accumulated on the backflow prevention valve 16 gradually increases in the return path 7 and the head pressure increases. On the other hand, since the working fluid 11 is not supplied in the heat receiving space 12, the working fluid 11 gradually decreases as the working fluid 11 is vaporized, and the pressure in the heat receiving space 12 decreases.

  The pressure upstream of the backflow prevention valve 16 (the sum of the pressure near the upstream of the backflow prevention valve 16 and the head pressure of the working fluid 11 in the return path 7) is the pressure downstream of the backflow prevention valve 16 (backflow prevention valve 16 The pressure of the backflow prevention valve 16 is pushed down and opened, the working fluid 11 passes through the backflow prevention valve 16, and the working fluid 11 is again supplied onto the heat receiving plate 10 of the heat receiving space 12. The

  In the heat receiving space 12, the working fluid 11 that has passed through the check valve 16 is supplied from the inlet 14 onto the heat receiving plate 10. Part of the supplied working fluid 11 is vaporized by the heat of the heat receiving plate 10. Then, the working fluid 11 is diffused at a high speed from the gap between the inlet 14 and the heat receiving plate 10 to the outer peripheral portion along with the non-boiling working fluid 11 by volume expansion due to vaporization. At this time, the working fluid 11 spreads as a thin film on the surface of the heat receiving plate 10, and heat from the high temperature heat receiving plate 10 is applied to vaporize in an instant.

  The internal pressure of the cooling device 3 including the heat receiving space 12 varies depending on the working fluid 11 used. For example, when water is used as the working fluid 11, the water in the atmospheric pressure is set by setting the pressure lower than the atmospheric pressure. It can be vaporized at a temperature lower than that of boiling. In the present embodiment, desired water is sealed in the cooling device 3 whose pressure is reduced to a substantially vacuum, and a saturated water vapor state corresponding to the outside air temperature is maintained, so that the outside temperature + a vaporization temperature of about several tens of degrees can be easily achieved. Water can be vaporized.

  As a result, the heat generated from the semiconductor switching element 9 is removed to the working fluid 11 as latent heat of vaporization and sensible heat, thereby enabling efficient cooling.

  Further, when the working fluid 11 is vaporized, the pressure in the heat receiving space 12 increases. However, the working fluid 11 does not flow back to the return path 7 due to the action of the backflow prevention valve 16, and the discharge port 15 is reliably connected. To the heat dissipation path 6.

  By operating the cooling device 3 in this manner, a regular heat receiving and releasing cycle can be performed, and the working fluid 11 is continuously vaporized in the heat receiving space 12 to efficiently remove the heat from the semiconductor switching element 9. A great cooling effect can be realized.

  Next, the most characteristic part in this embodiment will be described.

  As shown in FIG. 2, the vertical portion arranged in the vertical direction of the heat radiation path 6 connected to the discharge port 15 is divided into two paths of a main path 6a and a sub path 6b, and the sub path 6b is divided into the main path 6a. It has an inscribed configuration. The vertical cross-sectional area A2 with respect to the circulation direction of the working fluid 11 in the sub-path 6b is relatively smaller than the vertical cross-sectional area A1 of the main path 6a.

  It is known as a capillary phenomenon that the surface tension of the liquid existing in the pipe increases as the cross-sectional area of the pipe decreases, and the force acts in the direction of pushing up the surface of the liquid. That is, by making the cross-sectional area of the sub-path 6b smaller than the cross-sectional area of the main path 6a, the surface tension of the working fluid 11 in the sub-path 6b increases, and the force in the direction of pushing up the working fluid 11 in the sub-path 6b is increased. Therefore, the working fluid 11 toward the heat radiating part 5 can be easily carried from the main path 6a. As a result, the working fluid 11 can be smoothly circulated from the heat receiving portion 4 to the heat radiating portion 5 even with a low heat generation amount at the time of startup, and as a result, a decrease in cooling performance can be prevented.

  Furthermore, at the same time, it is possible to prevent the pulsation phenomenon that occurs in the single riser when the conventional cooling device is started and the heated liquid phase moves back and forth between the heating unit side and the cooler side.

  Here, the above-described pulsation phenomenon will be described in more detail with reference to FIGS. 3, 4, and 5. FIG. 3 is a schematic view showing the state of the working fluid in the ascending pipe 103 when the conventional cooling device is started. In FIG. 3A, a part of the working fluid (heat medium) that has contacted the rising pipe that has received heat from the heating unit in the very initial state of activation evaporates on the pipe wall surface to form a large number of bubbles. State. When the tube diameter is sufficiently large, normally, even if the heating amount increases, only the bubble size increases, and this state is continued. However, in the state where the diameter of the riser pipe is reduced and the upper meniscus 108 is formed on the inner wall surface of the riser pipe due to the surface tension of the working fluid, as shown in FIG. The working fluid is pushed up as one lump. Even in such a state, if the surface tension of the working fluid is large and the upper and lower meniscuses can be maintained, the mass of the working fluid is pushed up to the cooler side with an increase in pressure on the heating unit side. However, if the surface tension of the working fluid is not strong enough to maintain the upper and lower meniscuses, the upper and lower meniscuses collapse while moving up the tube, and all flow back to the heating part side as shown in FIG. Become. Usually, the phenomenon of repeating FIGS. 3A to 3C is called a pulsation phenomenon. When this phenomenon is viewed from the cooling device, once the high-temperature working fluid that has received heat as sensible heat from the heating part does not reach the cooler and flows back to the heating part, it functions as a heat transport medium. However, the sensible heat always accumulates in the heating part, and the cooling device using the phase change is a phenomenon that causes a serious decrease in cooling performance and unstable operation. Further, as shown in FIG. 3B, in order to push a large amount of working fluid up to the cooler side at the time of startup, it is necessary to increase the pressure on the heating unit side as described above, which increases the saturation temperature of the working fluid. As a result, the cooling performance is reduced. In addition, FIG. 4 is a graph in a case where the state where the pulsation phenomenon described in FIG. FIG. 4A shows the relationship between the gas phase circulation amount Wg and the liquid phase circulation amount Wl of the working fluid with respect to the input heat quantity Q. From the figure, in the range where the input heat quantity is low, that is, near the start-up time, the working fluid It shows that the circulation amount of is extremely low. FIG. 4B shows the pressure P in the heat receiving portion with respect to the input heat quantity Q at this time, and shows that there is a sudden pressure increase and pressure fluctuation in a very low working fluid circulation range. Yes. This high pressure fluctuation region indicates a state in which the pulsation phenomenon occurs.

  Normally, it is effective to reduce the cross-sectional area of the heat dissipation path in order to prevent the pulsation phenomenon. However, a cooling device using phase change involves a large volume expansion at the stage of vaporization of the working fluid, so simply reducing the cross-sectional area of the heat dissipation path will lead to a reduction in the maximum heat transport amount itself. become. FIG. 5 illustrates this point. FIG. 5 (a) shows the input heat quantity Q and the heat receiving portion internal pressure P when the tube diameter of the heat radiation path is changed. In the pipe cross-sectional area A1, which is a single pipe having a large cross-sectional area indicated by a thick solid line, in the range where the input heat quantity Q is small, that is, in the range where the heat generation amount at startup is small, Since the change is repeated up and down, it can be seen that a pulsation phenomenon occurs.

  On the other hand, in the pipe cross-sectional area A2, which is a single pipe having a small cross-sectional area indicated by a thin solid line, the surface tension of the working fluid is increased by reducing the pipe diameter, so that the upper and lower meniscuses do not collapse and the working fluid mass Therefore, in the range where the input heat quantity Q is small, the pressure P in the heat receiving part does not rise as much as the pipe cross-sectional area A1, which is a single pipe having a large cross-sectional area, and does not change up and down. It turns out that it has not occurred. However, in the pipe cross-sectional area A2 which is a single pipe having a small cross-sectional area, the pipe cross-sectional area is small, so that the pressure rises abruptly on the high calorific value side, indicating that it cannot cope with the high heat quantity. .

  On the other hand, the cross-sectional area A3 when the vertical part of the heat radiation path shown in Embodiment 1 of the present invention is constituted by the main path 6a and the sub-path 6b is a graph represented by a dotted line. In the case of the cross-sectional area A3, in the range of the low calorific value, the pressure rise and pulsation phenomenon at the start-up are suppressed as in the pipe cross-sectional area A1, and on the high calorific value side, a low pressure state comparable to the large pipe cross-sectional area A1. It can be seen that That is, by configuring the vertical portion of the heat dissipation path b6 shown in the first embodiment of the present invention with the main path 6a and the sub-path 6b, the pressure rise and the pulsation phenomenon at the time of the low heat generation amount are suppressed, and the high heat generation amount. This is a result showing that sufficient performance can be secured. FIG. 5B is a graph showing a path cross-sectional area ratio (A2 / A1) that is a ratio of the main path cross-sectional area A1 and the sub-path cross-sectional area A2 of the heat dissipation path and the maximum pressure P3 at the time of startup. From the figure, it is understood that the path cross-sectional area (A2 / A1) should be selected in the range of 0.1 to 0.5.

  Next, with reference to FIG. 6, additional explanation will be given for other arrangement relationships of the main path 6 a and the sub-path 6 b in the vertical portion of the heat radiation path 6 described in FIG. 2. 6A is a configuration example in which the axes of the main path 6a and the sub-path 6b of the heat dissipation path 6 are arranged concentrically, and FIG. 6B is a partition plate in the main path 6a of the heat dissipation path 6. In this example, the sub-path 6b is inscribed.

  Furthermore, FIG. 7 shows Embodiment 2 of the present invention. In the case of the first embodiment up to FIG. 6, the sub route 6b of the heat dissipation path 6 is arranged inside the main route 6a. In this case, the sub route 6b is provided outside the main route 6a. ing. However, the characteristics as a cooling device can realize the same cooling performance as in the first embodiment.

  As described above, the use of the first embodiment of the present invention prevents the cooling performance from being lowered and unstable operation at the start-up, and also maintains the stable high cooling performance in a wide range from the low heat generation amount to the high heat generation amount. An apparatus can be realized.

  In addition, in the said embodiment, although demonstrated as what applied the cooling device 3 to the electric vehicle 1, the cooling device 3 can also be applied to an electronic device.

  The cooling device according to the present invention can realize a cooling device that maintains stable and high cooling performance in a wide range from a low calorific value to a high calorific value, and has a large variation in the calorific value of electronic devices and electric vehicles. Useful for cooling in the circuit.

DESCRIPTION OF SYMBOLS 1 Electric vehicle 2 Inverter circuit 3 Cooling device 4 Heat receiving part 5 Heat radiating part 6 Heat radiating path 6a Main path 6b Sub path 7 Return path 8 Blower 9 Semiconductor switching element 10 Heat receiving plate 11 Working fluid 12 Heat receiving space 13 Heat receiving plate cover 14 Inlet 15 Discharge port 16 Backflow prevention valve

Claims (7)

A heat receiving section for transferring heat from the heat generating element to the working fluid from a heat receiving plate in contact with the heat generating element;
A heat dissipating part for releasing the heat of the working fluid;
A heat dissipation path and a return path that connect the heat receiving section and the heat dissipation section;
A cooling device that circulates the working fluid to the heat receiving portion, the heat radiating path, the heat radiating portion, the return path, and the heat receiving portion to move heat;
The return path includes a backflow prevention valve,
When the pressure upstream of the backflow prevention valve becomes higher than the pressure downstream of the backflow prevention valve, the working fluid passes through the backflow prevention valve, and the working fluid is supplied onto the heat receiving plate and supplied. The working fluid is diffused from the gap between the inlet and the heat receiving plate to the outer periphery, and the working fluid spreads and vaporizes as a thin film on the surface of the heat receiving plate.
The vertical part of the heat dissipation path is composed of a main path and a sub-path,
The cooling device according to claim 1, wherein a cross-sectional area of the sub path is smaller than a cross-sectional area of the main path. The cooling device according to claim 1, wherein the sub route is inscribed in the main route. The cooling apparatus according to claim 1, wherein the sub path is disposed concentrically with the main path. The cooling device according to claim 1, wherein the sub route circumscribes the main route. The cooling device according to claim 1, wherein an area ratio A2 / A1 of the cross-sectional area A1 of the main path and the cross-sectional area A2 of the sub-path is in a range of 0.1 to 0.5. An electronic apparatus comprising the cooling device according to claim 1. An electric vehicle comprising the cooling device according to any one of claims 1 to 6.