JP7725565B2 - boiling cooler - Google Patents

Description

This invention relates to a boiling type cooler, and more particularly to a boiling type cooler that circulates refrigerant between a boiling section that boils the refrigerant and a condensing section that condenses the vaporized refrigerant.

Conventionally, boiling-type coolers that circulate a refrigerant between a boiling section and a condensing section are known. Such boiling-type coolers are disclosed, for example, in Japanese Patent Application Laid-Open No. 2002-134670.

The above-mentioned Japanese Patent Application Laid-Open No. 2002-134670 discloses a structure in which a condenser section consisting of a plate-fin heat exchanger in an inverted T shape is joined to the top surface of a horizontally arranged evaporator section (boiling section). A refrigerant is sealed inside the evaporator section. A plate for mounting semiconductor elements is provided on the bottom surface of the evaporator section.

Japanese Patent Application Laid-Open No. 2002-134670

In this specification, a boiling cooler with a boiling portion that extends horizontally, such as the boiling cooler disclosed in Japanese Patent Application Laid-Open No. 2002-134670, is referred to as a "horizontal" boiling cooler. In a horizontal boiling cooler, the heating element must be installed on the underside of the boiling portion. This is because liquid refrigerant accumulates in the lower part of the boiling portion and gaseous refrigerant gas accumulates in the upper part, making it difficult to achieve sufficient cooling performance even if the heating element is installed on the upper surface of the boiling portion. Therefore, a challenge with horizontal boiling coolers is that it is difficult to secure the installation area for the heating element.

This invention was made to solve the above-mentioned problems, and one object of this invention is to provide a boiling cooler that allows for a larger installation area for the heating element, even if it is a horizontal boiling cooler.

In order to achieve the above object, a boiling type cooler according to the present invention has a storage space for storing a refrigerant, and comprises: a boiling section having an accommodation space for storing a refrigerant and boiling the refrigerant through heat exchange with a heating element; and a condensing section communicating with the boiling section and condensing refrigerant gas from the boiling section through heat exchange with an external fluid, the boiling section being formed in a plate-like shape with upper and lower surfaces on which the heating elements are respectively installed, and extending obliquely downward from a connection portion with the condensing section, and further including a partition plate dividing the accommodation space into an upper space adjacent to the upper surface and a lower space adjacent to the lower surface, the condensing section being provided so as to extend upward from the upper surface of the boiling section, and a through hole formed in the upper surface of the boiling section connecting the accommodation space and the condensing section , the through hole being configured to allow refrigerant gas to flow into the condensing section and condensed refrigerant to flow into the accommodation space, the partition plate being provided throughout the entire accommodation space, and having a first communication passage penetrating the partition plate in a region vertically overlapping with the through hole in the upper surface to connect the upper space and the lower space .

In the boiling type cooler according to the present invention, as described above, the boiling portion extends obliquely downward from the connection portion with the condensing portion. This allows the inner upper surface of the refrigerant storage space to be inclined relative to the liquid refrigerant level, allowing the inner upper surface of the storage space to be continuously in contact with the liquid refrigerant. The condensing portion extends upward from the upper surface of the boiling portion. The upper surface of the boiling portion is formed with a through-hole that connects the storage space and the condensing portion. The through-hole is configured to allow refrigerant gas to flow into the condensing portion and condensed refrigerant to flow into the storage space. Since the storage space is inclined upward toward the condensing portion, refrigerant gas vaporized within the storage space moves along the inclined storage space toward the condensing portion. This prevents excessive stagnation of refrigerant gas on the inner upper surface of the storage space. As a result, sufficient cooling performance can be achieved even for a heat-generating element placed on the upper surface of the boiling portion. Therefore, by allowing the heat-generating element to be placed on both the upper and lower surfaces of the boiling portion, the installation area for the heat-generating element can be increased, even in a horizontal boiling type cooler. The boiling portion further includes a partition plate that divides the storage space into an upper space adjacent to the upper surface and a lower space adjacent to the lower surface. With this configuration, the partition plate can prevent refrigerant gas generated in the lower space of the storage space due to heat absorption from a heating element installed on the lower surface of the boiling portion from migrating to the upper space. This prevents all refrigerant gas from concentrating on the interior upper surface of the storage space (upper space), preventing contact between the refrigerant and the interior upper surface. This improves the cooling performance of the heating element on the upper surface of the boiling portion. It is also known that in heat exchangers, a state in which a liquid and gas phase are present at a moderate ratio rather than a state in which the heat transfer surface is completely filled with liquid due to the effect of evaporation of a liquid film along the heat transfer surface improves cooling performance. Therefore, if the partition plate blocks refrigerant gas generated in the lower space, resulting in a moderate ratio of liquid and gas phases on the interior upper surface of the upper space, more effective improvement in cooling performance on the upper surface can be expected. The partition plate is provided throughout the entire storage space, and in a region vertically overlapping with the through-hole on the upper surface, a first communication passage penetrates the partition plate to connect the upper space and the lower space. With this configuration, the partition plate is provided throughout the entire storage space, reliably preventing refrigerant gas generated in the lower space from collecting on the interior upper surface of the storage space. Furthermore, since the refrigerant gas generated in the lower space moves along the partition plate, the refrigerant gas in the lower space can pass through the first communication passage and move toward the condensing section. This eliminates the need to form a separate passage in the boiling section for moving the refrigerant gas in the lower space to the condensing section, thereby simplifying the structure of the boiling cooler. Note that, in this specification, a horizontal boiling cooler includes a boiling cooler in which the horizontal dimension of the boiling cooler is greater than the vertical dimension of the boiling cooler and the boiling cooler is inclined from the horizontal. In other words, if the boiling cooler has a simple flat plate shape and is inclined at an angle of less than 45 degrees to the horizontal, it is considered a "horizontal" boiling cooler.

In the above invention, the boiling portion is preferably inclined so that the liquid level of the refrigerant is located within the area on the upper surface where the heating element is installed or above the area where the heating element is installed. This configuration allows the area of the interior upper surface of the storage space facing the area where the heating element is installed (the area directly below the heating element) to come into contact with the liquid refrigerant. This prevents the area directly below the heating element from partially drying out, effectively preventing localized temperature increases (localized reductions in cooling performance). Dryout occurs when the liquid refrigerant disappears from the heat transfer surface and the heat transfer surface is covered with gaseous refrigerant (a single-phase vapor state), resulting in a significant decrease in the heat transfer coefficient in the area where dryout occurs.

In the above invention, the boiling portion is preferably inclined at an angle of 5 degrees or more and less than 45 degrees with respect to the horizontal direction. This configuration provides the advantage of a horizontal boiling type cooler, namely, the ability to reduce the height of the boiling type cooler, while also allowing the heating element to be installed on the upper surface of the boiling portion, resulting in a horizontal boiling type cooler with a larger installation area for the heating element.

In a configuration in which the boiling section includes a partition plate, a second communication passage is preferably formed at one end of the storage space located on the lower side, connecting the upper space and the lower space. With this configuration, even when the storage space is partitioned into the upper space and the lower space, liquid-phase refrigerant can be moved via the second communication passage. Therefore, the amount of refrigerant stored in the upper space and the lower space can be made uniform, without the refrigerant being stored unevenly in either the upper space or the lower space.

In the above invention, the condensing section preferably has an external fluid flow passage that passes horizontally through the condensing section. With this configuration, even if the boiling section is tilted diagonally downward, the condensing section extends vertically, allowing the external fluid to be fed horizontally to the condensing section. For example, when condensing the refrigerant gas in the condensing section through forced cooling that feeds the external fluid using a drive source, it is not necessary to tilt the drive source or the external fluid flow path to match the inclination of the boiling section. Therefore, when combining the boiling type cooler with an external device, the boiling type cooler can be easily adapted to the external device.

As described above, according to the present invention, even in a horizontal boiling-type cooler, the installation area of the heating element can be increased.

1 is a schematic perspective view showing an overall configuration of a cooler according to an embodiment ; FIG. 2 is a schematic longitudinal cross-sectional view of the cooler of FIG. 1 taken along the YZ direction. FIG. 2 is a schematic vertical cross-sectional view taken along the EZ direction, showing the internal structure of the boiling portion. FIG. 2 is a schematic enlarged longitudinal cross-sectional view of the boiling portion along the X direction. FIG. 2 is a schematic plan view showing the upper surface of the boiling portion. FIG. 2 is a schematic plan view showing a partition plate. FIG. 4 is a schematic cross-sectional view showing a second member of the boiling portion. FIG. 4 is a schematic diagram illustrating the operation of a cooler according to an embodiment . FIG. 10 is a schematic longitudinal cross-sectional view of a boiling portion according to a reference example taken along the EZ direction. FIG. 10 is a schematic vertical cross-sectional view of a boiling portion according to a reference example taken along the X direction. 10A and 10B are schematic diagrams for explaining the operation of a cooler in a reference example . FIG. 10 is a schematic diagram showing a boiling portion according to a comparative example. 10 is a graph showing experimental results 1 for a heat generation amount of 50% according to an embodiment. 10 is a graph showing experimental results 2 for a heat generation amount of 100% according to an embodiment. 10 is a graph showing experimental results 3 for a heat generation amount of 150% according to an embodiment. 16 is a graph summarizing the experimental results shown in FIGS. 13 to 15. 10A and 10B are schematic diagrams showing modified examples of the orientation of the condensation section. 10A and 10B are schematic diagrams showing modified examples of the inclination angle of the boiling portion. 10A and 10B are schematic diagrams showing modified examples of the range in which the partition plate is formed. FIG. 10 is a schematic diagram showing a modified example in which a through hole is formed in the partition plate. 10A and 10B are schematic diagrams showing modified examples of the first communicating portion and the second communicating portion.

Embodiments of the present invention will be described below with reference to the drawings.

[ One embodiment ]
The configuration of an ebullient cooler 100 (hereinafter referred to as the cooler 100) according to one embodiment will be described with reference to Figures 1 to 8. The cooler 100 is a cooler that uses an ebullient cooling method, utilizing the phase change between vaporization and condensation of a refrigerant to absorb heat from a heat-generating body HS and release the heat to the outside. The cooler 100 cools the heat-generating body HS by heat absorption by the refrigerant. The refrigerant gas that has been vaporized by heat absorption is cooled by an external fluid, condenses, and returns to a liquid phase.

The heating element HS is not particularly limited. For example, the heating element HS is a device equipped with an electronic circuit. Specifically, it is a power module that constitutes a power conversion circuit such as an inverter device. A power module is a circuit component equipped with one or more power conversion switching elements. The power conversion switching elements are, for example, IGBT (insulated gate bipolar transistor) elements.

(Overall configuration of the cooler)
As shown in Fig. 1, the cooler 100 includes a boiling portion 10, a condensing portion 20, and a connecting portion 30. A space (see Fig. 2) for accommodating the refrigerant 1 is formed inside each of the boiling portion 10, the condensing portion 20, and the connecting portion 30. The cooler 100 has an internal space sealed by the boiling portion 10, the condensing portion 20, and the connecting portion 30. The refrigerant 1 is accommodated in this sealed space. The boiling portion 10, the condensing portion 20, and the connecting portion 30 are made of a metal material with high thermal conductivity, such as aluminum (including aluminum alloys) or copper (including copper alloys).

Refrigerant 1 is not particularly limited as long as it changes phase between gas and liquid. Therefore, refrigerant 1 may be selected from known refrigerants depending on the heating element HS, and examples include fluorocarbons, hydrocarbons, and water. The internal space of cooler 100 is depressurized to a near-vacuum state, and is in a saturated vapor state with gas-phase refrigerant 1. For convenience, when distinguishing between different states of refrigerant 1, gas-phase refrigerant 1 is referred to as refrigerant gas 1a (see Figure 2), and liquid-phase refrigerant 1 is referred to as refrigerant liquid 1b (see Figure 2).

In the following, two mutually perpendicular directions in a horizontal plane are referred to as the X direction and the Y direction, respectively. The vertical direction perpendicular to the horizontal plane (X-Y plane) is referred to as the Z direction. Note that the Z direction is approximately parallel to the direction of gravity, and gravity acts downward. As will be explained later, the direction in which the boiling portion 10 extends is referred to as the E direction. In the following explanation, the E direction is included in the Y-Z plane and is inclined downward at an angle θ with respect to the Y direction.

In the example shown in FIG. 1, four heating element HS installation areas are provided on the upper surface 12 of the boiling section 10, and four heating element HS installation areas are provided on the lower surface 13 of the boiling section 10. That is, on each of the upper surface 12 and the lower surface 13, there are two columns of installation areas in the X direction and two rows in the Y direction (strictly speaking, the E direction). The cooler 100 has a structure in which multiple unit structures SU are arranged in the X direction, with one column representing a unit structure SU. Each unit structure SU has substantially the same structure. Therefore, the following description will focus on one unit structure SU. Note that while FIG. 1 shows an example configuration with two unit structures SU, the cooler 100 may have only one unit structure SU, or three or more unit structures SU.

A heating element HS is installed in the boiling portion 10. As shown in Figure 2, the boiling portion 10 has a storage space 11 that stores the refrigerant 1. Refrigerant liquid 1b is stored in the storage space 11 of the boiling portion 10 due to the action of gravity. The boiling portion 10 is configured to boil the refrigerant 1 (refrigerant liquid 1b) through heat exchange with the heating element HS. The boiling portion 10 has an upper surface 12 and a lower surface 13. The boiling portion 10 has two side surfaces 14 on either side in the X direction (see Figure 1), and an end surface 15 at one end E1 and an end surface 16 at the other end E2 in the E direction. The boiling portion 10 has a plate-like shape including the upper surface 12, lower surface 13, two side surfaces 14, and two end surfaces 15, 16.

An installation area for the heating element HS is provided on one end E1 of the boiling portion 10. The condensation portion 20 is connected to the other end E2 of the boiling portion 10 via a connection portion 30. The boiling portion 10 is arranged to extend diagonally downward from the connection portion with the condensation portion 20 (i.e., connection portion 30). The boiling portion 10 is arranged to be inclined downward at an angle θ with respect to the horizontal direction (Y direction). As a result, the boiling portion 10 extends linearly in the E direction, diagonally downward from the connection portion with the condensation portion 20. A through hole 12a is formed in the upper surface 12 of the boiling portion 10, connecting the storage space 11 and the condensation portion 20.

The connecting portion 30 has a cylindrical shape extending in the Z direction. The lower end surface of the connecting portion 30 is joined to the upper surface 12 of the boiling portion 10, and the upper end surface of the connecting portion 30 is joined to the lower surface of the condensing portion 20. The lower end surface of the connecting portion 30 is inclined at an angle θ to match the upper surface 12 of the boiling portion 10, which is inclined diagonally downward. The upper end surface of the connecting portion 30 is along the horizontal plane (X-Y plane). The connecting portion 30 is arranged to surround the through-hole 12a formed in the upper surface 12 of the boiling portion 10. The connecting portion 30 provides an airtight connection between the storage space 11 of the boiling portion 10 and the storage space 21a of the condensing portion 20.

The connection portion 30 forms a passage through which the refrigerant gas 1a vaporized in the boiling portion 10 moves to the condensing portion 20, and also forms a passage through which the refrigerant liquid 1b condensed in the condensing portion 20 moves to the boiling portion 10. In this embodiment , the movement path of the refrigerant gas 1a and the movement path of the refrigerant liquid 1b are the same. That is, the boiling portion 10 and the condensing portion 20 are connected by a single passage (connection portion 30). In the single passage (connection portion 30), the refrigerant gas 1a moving to the condensing portion 20 and the refrigerant liquid 1b moving to the boiling portion 10 are mixed in a gas-liquid mixed phase state. Therefore, the device structure can be simplified compared to a type of cooler that forms a loop-shaped internal space in which the boiling portion 10 and the condensing portion 20 are separately connected by a passage dedicated to the refrigerant gas 1a and a passage dedicated to the refrigerant liquid 1b.

The condenser section 20 extends upward from the upper surface 12 of the boiling section 10 via the connection section 30. The condenser section 20 is connected to the boiling section 10 via the connection section 30. The condenser section 20 is configured to condense the refrigerant gas 1a from the boiling section 10 through heat exchange with the external fluid 2.

The condensation section 20 has a storage space 21a that stores the refrigerant 1. As shown in FIG. 1, the condensation section 20 has a flow passage 22 for the external fluid 2 that passes through the condensation section 20 horizontally (in the Y direction). The flow passage 22 is a passage that is open to the outside of the condensation section 20. The storage space 21a (see FIG. 2) is the internal space of the condensation section 20 that is surrounded by a wall 24 that defines the flow passage 22. In other words, the storage space 21a and the flow passage 22 are partitioned by the wall 24 that constitutes the condensation section 20 so that they do not communicate with each other. The storage space 21a (see FIG. 2) is provided inside the refrigerant storage section 21 in FIG. 1.

In the condenser section 20, multiple refrigerant storage sections 21 and multiple circulation channels 22 are arranged alternately in the X direction. Corrugated fins 23 are provided in the circulation channels 22 from one end to the other in the Y direction. The external fluid 2 passing through the circulation channels 22 is air. As shown in Figure 2, when the cooler 100 is in operation, a blower 3 is provided as a driving source for the external fluid 2, blowing air in the Y direction along the circulation channels 22.

The storage space 21a is open on the lower side in the Z direction and is surrounded by a wall 24 on the upper side in the X, Y, and Z directions. The lower end of the wall 24 is joined to the upper end of the connection part 30. The open underside of the storage space 21a is in communication with the storage space 11 of the boiling part 10 via the connection part 30. Therefore, the cooler 100 has a closed internal space composed of the storage space 11 of the boiling part 10, the interior of the connection part 30, and the storage space 21a of the condensing part 20. Refrigerant 1 is sealed in this internal space.

Fins 25 extending in the Z direction are provided in the storage space 21a.

As shown in Figure 2, refrigerant gas 1a vaporized in boiling section 10 flows through connection section 30 into storage space 21a of condensing section 20, where it diffuses upward through fins 25. Condensing section 20 transfers the heat of refrigerant gas 1a flowing into storage space 21a to external fluid 2 passing through flow passage 22 (see Figure 1), condensing (liquefying) refrigerant gas 1a. Refrigerant liquid 1b condensed through heat exchange with external fluid 2 is returned to boiling section 10 via connection section 30, primarily due to the action of gravity.

As a result, inside the cooler 100, the refrigerant 1 circulates between the boiling section 10 and the condensing section 20, repeating a cycle of phase change between vaporization of the refrigerant 1 in the boiling section 10 and condensation of the refrigerant 1 in the condensing section 20.

(Inclination angle of boiling part)
As shown in FIG. 2 , in this embodiment , the boiling portion 10 is inclined so that the liquid level 1c of the refrigerant 1 (refrigerant liquid 1b) is located within the installation area of the heating element HS on the upper surface 12. That is, the liquid level 1c is located within a height range between the lower and upper ends of the installation area of the heating element HS on the upper surface 12. Specifically, the liquid level 1c is located at a height that approximately coincides with the upper end of the installation area of the heating element HS on the upper surface 12. The position of the liquid level 1c is the position when the cooler 100 is in an inoperative state. The installation area is the area of the upper surface 12 that is covered by the heating element HS when the heating element HS is installed (the so-called footprint). The boiling portion 10 is inclined at an angle θ of 5 degrees or more and less than 45 degrees with respect to the horizontal. In the example of FIG. 2 , the angle θ is 10 degrees.

(Structure of boiling part)
Next, the structure of the boiling portion 10 will be described in detail with reference to Figures 3 to 7. As shown in Figure 3, the boiling portion 10 is configured in a hollow, flat shape by joining lid members 43 to one end E1 and the other end E2 of a cylindrical case member 40. The case member 40 has an upper surface 12, a lower surface 13, and two side surfaces 14 (see Figure 1). The two lid members 43 form an end surface 15 of the one end E1 and an end surface 16 of the other end E2. The case member 40 includes an upper first member 41 including the upper surface 12 and a lower second member 42 including the lower surface 13.

The storage space 11 is formed to extend in the E direction from one end E1 of the boiling section 10 to the other end E2. Hereinafter, the inner surface of the storage space 11 on the upper surface 12 side is referred to as the inner upper surface 41a, and the inner surface of the storage space 11 on the lower surface 13 side is referred to as the inner lower surface 42a. The inner upper surface 41a is the inner surface of the first member 41, and the upper surface 12 is the outer surface of the first member 41. The inner lower surface 42a is the inner surface of the second member 42, and the lower surface 13 is the outer surface of the second member 42. A through-hole 12a is formed in the first member 41 to communicate the storage space 11, the interior of the connection section 30 (see Figure 2), and the storage space 21a of the condenser section 20 (see Figure 2). The through-hole 12a penetrates the first member 41 from the upper surface 12 to the inner upper surface 41a.

In this embodiment , the boiling portion 10 further includes a partition plate 44 that divides the accommodation space 11 into an upper space 11a adjacent to the upper surface 12 and a lower space 11b adjacent to the lower surface 13. The partition plate 44 is a flat plate member extending along the E direction. As shown in FIG. 4 , the partition plate 44 is provided so as to be sandwiched between the first member 41 and the second member 42.

The partition plate 44 divides the storage space 11 into two spaces: an upper space 11a and a lower space 11b. The partition plate 44 is arranged parallel to the upper surface 12 and the lower surface 13. Therefore, the upper space 11a and the lower space 11b extend in the E direction and are arranged parallel to each other. The upper space 11a and the lower space 11b are both formed to extend in the E direction from one end E1 of the boiling portion 10 to the other end E2. In the example shown in Figure 4, the partition plate 44 divides the storage space 11 into two equal parts. That is, in the thickness direction of the boiling portion 10, the height h1 of the upper space 11a and the height h2 of the lower space 11b are equal.

As shown in Figure 3, the partition plate 44 is provided in at least an area OA that overlaps with the installation area of the heating element HS on the upper surface 12 in the thickness direction of the boiling section 10. The installation area of the heating element HS on the upper surface 12 has a length L1 in the E direction and a width W1 in the X direction (see Figure 5). The partition plate 44 is provided over an area that either matches the range of length L1 and width W1 or is wider than the range of length L1 and width W1.

3 shows an example in which the position of the installation area on the upper surface 12 and the position of the installation area on the lower surface 13 are the same in the E direction, but the positions of the installation area on the upper surface 12 and the positions of the installation area on the lower surface 13 do not need to be the same and may be different. In this embodiment , as an example, an example is shown in which all the heating elements HS have the same shape (rectangular parallelepiped shape), but the shapes of the individual heating elements HS may be different, in which case the sizes of the installation areas may also be different.

In this embodiment , the partition plate 44 is provided across the entire storage space 11 (the entire length in the E direction and the entire width in the X direction). Therefore, the partition plate 44 completely divides the storage space 11 into an upper space 11a and a lower space 11b. Specifically, the storage space 11 has a length L in the E direction, a width W in the X direction (see FIG. 4), and a height H in the thickness direction of the boiling portion 10 (see FIG. 4). The partition plate 44 is formed within the range of the length L and width W, and is positioned at a position that divides the storage space 11 in the thickness direction into heights h1 and h2.

In a configuration in which the partition plate 44 separates the entire storage space 11, as shown in FIG. 3, the upper space 11a is in direct communication with the through-hole 12a, but the lower space 11b is separated from the through-hole 12a by the partition plate 44. Therefore, in the region where the partition plate 44 overlaps the through-hole 12a on the upper surface 12, a first communication passage 45 penetrates the partition plate 44 to connect the upper space 11a and the lower space 11b. The first communication passage 45 is a passage that transfers refrigerant gas 1a generated in the lower space 11b to the through-hole 12a, and a passage that transfers refrigerant liquid 1b returning from the condensation section 20 to the boiling section 10 to the lower space 11b. In the example shown in FIG. 3, the first communication passage 45 is a through-hole that penetrates the partition plate 44 in the thickness direction.

In this embodiment , a second communication passage 46 that connects the upper space 11a and the lower space 11b is formed at one end E1 located on the lower side of the accommodation space 11. Note that, as shown in FIG. 2, the lower end E1 refers to the end that is located relatively lower in the Z direction of both ends of the boiling portion 10 that extend diagonally downward (in the E direction). The other end E2 is located relatively higher in the Z direction. In the example shown in FIG. 3, the second communication passage 46 is a notch provided at one end of the partition plate 44.

The second communication passage 46 is provided at one end E1, allowing refrigerant liquid 1b to move between the upper space 11a and the lower space 11b at the lowest point of the storage space 11. In the example shown in FIG. 2, the liquid level 1c of the refrigerant 1 is below the first communication passage 45 (at the upper end of the installation area on the top surface 12). In this case, the refrigerant liquid 1b stored in the upper space 11a and the refrigerant liquid 1b stored in the lower space 11b are separated by the partition plate 44. However, because refrigerant liquid 1b can move between the upper space 11a and the lower space 11b via the second communication passage 46, the amount of stored liquid can be adjusted so that the liquid level in the upper space 11a and the liquid level in the lower space 11b are aligned.

Figure 5 shows the planar shape of the first member 41 (boiling portion 10). An installation area is formed on the upper surface 12 of the boiling portion 10, with a length L1 and a width W1, and a through-hole 12a is formed with a length L2. In the example of Figure 5, a rectangular through-hole 12a extending in the X direction is formed within the length L2 range.

Figure 6 shows the planar shape of the partition plate 44. The partition plate 44 has a through hole that forms the first communication passage 45 and a notch that forms the second communication passage 46. The partition plate 44 is formed continuously between the first communication passage 45 and the second communication passage 46 without interruption. The first communication passage 45 is formed by a through hole 44a. The through hole 44a has a rectangular shape. The second communication passage 46 has a rectangular shape extending in the X direction.

In the example of Figure 6, a partition plate 44 is provided in a portion of the area on one end E1 side that overlaps with the through hole 12a (see dashed line) in the thickness direction of the upper surface 12. A first communication passage 45 is provided in a portion of the area on the other end E2 side that overlaps with the through hole 12a in the thickness direction. In the example of Figure 6, of the through holes 12a formed within the range of length L2, the partition plate 44 is provided in a region of length L4, which is approximately half the length of the through hole 12a on the one end E1 side. A first communication passage 45 (through hole 44a) is provided in a region of the through hole 12a of length L3, which is approximately half the length of the through hole 12a on the other end E2 side.

As a result, refrigerant liquid 1b returning from the condensing section 20 to the boiling section 10 through approximately half of the through-hole 12a on the one end E1 side is received by the partition plate 44 and distributed to the upper space 11a. Refrigerant liquid 1b returning from the condensing section 20 to the boiling section 10 through approximately half of the through-hole 12a on the other end E2 side passes through the first communication passage 45 and is distributed to the lower space 11b.

In this way, by forming a partition plate 44 on one end E1 side of the area overlapping with the through hole 12a and a first communication passage 45 on the other end E2 side, the distribution ratio of condensed refrigerant liquid 1b to the upper space 11a and the lower space 11b can be adjusted. Increasing the proportion of the area where the partition plate 44 is formed increases the distribution ratio of refrigerant liquid 1b to the upper space 11a, and increasing the proportion of the area where the first communication passage 45 is formed increases the distribution ratio of refrigerant liquid 1b to the lower space 11b. In the example of Figure 6, the partition plate 44 overlaps with approximately half of the through hole 12a, and the first communication passage 45 also overlaps with approximately half of the through hole 12a, so the distribution ratio of refrigerant liquid 1b is equal (1:1). The ratio of the area where the partition plate 44 is formed to the area where the first communication passage 45 is formed (the ratio of length L4 to length L3 within the range of length L2) can be set, for example, according to the ratio of the heat generation amount of the heating element HS installed on the upper surface 12 to the heat generation amount of the heating element HS installed on the lower surface 13.

As shown in FIG. 4, the lower space 11b is partitioned by the bottom plate portion 42b of the second member 42, two side wall portions 42c on both sides in the X direction, and the lower surface of the partition plate 44. Furthermore, as shown in FIG. 7, the lower space 11b is partitioned into multiple refrigerant passages 42e by partition wall portions 42d extending in the E direction. In the example of FIG. 7, three partition wall portions 42d are provided, and the lower space 11b is partitioned into four refrigerant passages 42e. As shown in FIG. 4, the upper surfaces of each of the two side wall portions 42c on both sides in the X direction and the upper surfaces of the three partition wall portions 42d are in contact with the lower surface of the partition plate 44.

The through-hole 44a (see Figure 6) that constitutes the first communication passage 45 is formed so as to straddle the positions where the four refrigerant passages 42e in the lower space 11b are formed. The width of the through-hole 44a in the X direction is approximately equal to the sum of the widths of the individual refrigerant passages 42e in the X direction.

As shown in FIG. 4, the first member 41 that constitutes the upper space 11a has a structure that is substantially the same as that of the second member 42, but with the exception of the through-hole 12a (see FIG. 5). The upper space 11a is defined by the top plate 41b of the first member 41, two side wall portions 41c on both sides in the X direction, and the upper surface of the partition plate 44. The upper space 11a is defined into multiple refrigerant passages 41e by partition portions 41d extending in the E direction. In the example shown in FIG. 4, three partition portions 41d are provided, and the upper space 11a is defined into four refrigerant passages 41e. The lower surfaces of the two side wall portions 41c on both sides in the X direction and the lower surfaces of the three partition portions 41d are in contact with the upper surface of the partition plate 44.

The length in the X direction of the second communication passage 46 (see Figure 6) cut out and formed in the partition plate 44 is approximately equal to the distance between the pair of side wall portions 42c (pair of side wall portions 41c) on both sides in the X direction shown in Figure 7. In other words, the second communication passage 46 is formed across the four refrigerant passages 42e in the lower space 11b and the four refrigerant passages 41e in the upper space 11a. As a result, the second communication passage 46 is configured to interconnect the multiple (eight) passages provided in the upper space 11a and lower space 11b.

As shown in Figure 4, the first member 41 and the second member 42 are joined together by a partition plate 44, forming an integrated unit. The partition plate 44 is made of a brazing sheet with brazing material on both sides. The upper and lower surfaces of the partition plate 44 are flat. The boiling section 10 is constructed by placing and brazing cover members 43 on one end E1 and the other end E2 of the assembly (case member 40) of the first member 41, the second member 42, and the partition plate 44.

(Cooler operation)
The operation of the cooler 100 will be described. FIG. 8 is a schematic diagram of the boiling portion 10 of the cooler 100. When the heating element HS generates heat, the generated heat is absorbed by the refrigerant 1 in the boiling portion 10. The heat from the heating element HS located on the upper surface 12 is absorbed by the refrigerant 1 contained in the upper space 11a, and the heat from the heating element HS located on the lower surface 13 is absorbed by the refrigerant 1 contained in the lower space 11b. Because the boiling portion 10 is inclined downward at an angle θ and the liquid level 1c of the refrigerant 1 is located at the upper end of the installation area, the area of the inner upper surface 41a of the upper space 11a that overlaps with the installation area is always in contact with the refrigerant liquid 1b. This prevents the inner upper surface 41a from drying out and becoming covered with refrigerant gas 1a. In each of the upper space 11a and the lower space 11b, the refrigerant 1 absorbs heat and boils to vaporize into refrigerant gas 1a.

Refrigerant gas 1a generated in upper space 11a moves along inner upper surface 41a toward the other end E2. Because inner upper surface 41a is inclined upward at angle θ toward the other end E2, refrigerant gas 1a is prevented from stagnating on inner upper surface 41a without moving. When refrigerant gas 1a released from liquid surface 1c reaches the position where through-hole 12a is formed, refrigerant gas 1a passes through through-hole 12a and moves into connection portion 30.

Refrigerant gas 1a generated in lower space 11b moves upward within lower space 11b, comes into contact with the lower surface of partition plate 44, and moves along partition plate 44 toward the other end E2. The partition plate 44 prevents refrigerant gas 1a generated in lower space 11b from moving upward to the internal upper surface 41a of upper space 11a, preventing excessive concentration of refrigerant gas 1a on the internal upper surface 41a. When refrigerant gas 1a released from liquid level 1c reaches the position where the first communication passage 45 is formed, refrigerant gas 1a passes through first communication passage 45 and moves into upper space 11a. Refrigerant gas 1a that has moved into upper space 11a continues to pass upward through upper space 11a and moves through through-hole 12a into connection portion 30.

Refrigerant gas 1a passes upward through the connection portion 30 and flows into the storage space 21a of the condenser portion 20 above. Within the storage space 21a, refrigerant gas 1a moves upward while diffusing through the gaps between the fins 25.

As shown in Figure 2, in the condenser section 20, heat exchange occurs between the refrigerant gas 1a in the storage space 21a and the external fluid 2 passing through the flow passage 22 (see Figure 1). Through the heat exchange, the refrigerant gas 1a releases condensation heat to the external fluid 2 and condenses into refrigerant liquid 1b. The condensed refrigerant liquid 1b falls from the storage space 21a into the connection section 30 and passes through the through-hole 12a to return to the refrigerant liquid 1b stored in the boiler section 10.

(Effects of this embodiment )
In this embodiment , the following effects can be obtained.

In this embodiment , as described above, the boiling portion 10 is configured to extend obliquely downward from the connection portion (connection portion 30) with the condensing portion 20. This allows the inner upper surface 41a of the storage space 11 for the refrigerant 1 to be inclined relative to the liquid level 1c of the refrigerant liquid 1b, thereby allowing the inner upper surface 41a of the storage space 11 to be continuously in contact with the refrigerant liquid 1b. Furthermore, because the storage space 11 is inclined upward toward the condensing portion 20, the refrigerant gas 1a vaporized within the storage space 11 moves along the inclined storage space 11 toward the condensing portion 20. This prevents the refrigerant gas 1a from excessively accumulating on the inner upper surface 41a of the storage space 11. As a result, sufficient cooling performance can be achieved for the heating element HS installed on the upper surface 12 of the boiling portion 10. Therefore, by allowing the heating element HS to be installed on not only the lower surface 13 but also the upper surface 12 of the boiling portion 10, the installation area for the heating element HS can be increased even in a horizontal boiling type cooler 100.

Furthermore, in this embodiment , as described above, the boiling section 10 is inclined at an inclination angle θ of 5 degrees or more and less than 45 degrees with respect to the horizontal direction, so that while obtaining the advantage of the horizontal boiling type cooler 100 that the height dimension of the boiling type cooler 100 can be reduced, the heating element HS can also be installed on the upper surface 12 of the boiling section 10, thereby obtaining a horizontal boiling type cooler 100 with a larger installation area for the heating element HS.

In the present embodiment , as described above, the boiling portion 10 further includes a partition plate 44 that divides the accommodation space 11 into an upper space 11a adjacent to the upper surface 12 and a lower space 11b adjacent to the lower surface 13. This allows the partition plate 44 to prevent refrigerant gas 1a generated in the lower space 11b of the accommodation space 11 from moving to the upper space 11a. This prevents all refrigerant gas 1a from gathering on the inner upper surface 41a, thereby preventing contact between the refrigerant liquid 1b and the inner upper surface 41a, thereby improving the cooling performance of the heating element HS on the upper surface 12 of the boiling portion 10. It is also known that in a heat exchanger, a state in which a liquid phase and a gas phase exist in an appropriate ratio improves cooling performance due to the evaporation of a liquid film along the heat transfer surface, rather than a state in which the heat transfer surface is completely filled with the liquid phase. Therefore, when the refrigerant gas 1a generated in the lower space 11b is blocked by the partition plate 44, and the liquid phase and gas phase on the internal upper surface 41a of the upper space 11a are in an appropriate ratio, further effective improvement in cooling performance on the upper surface 12 can be expected.

Furthermore, in this embodiment , as described above, the partition plate 44 is provided at least in the range OA that overlaps in the thickness direction of the boiling portion 10 with the installation area of the heating element HS on the upper surface 12, so that the partition plate 44 can prevent the refrigerant gas 1a generated in the lower space 11b from collecting in the area of the inner upper surface 41a of the accommodation space 11 directly below the heating element HS on the upper surface 12 of the boiling portion 10. Therefore, the refrigerant gas 1a can be effectively prevented from collecting in the area of the inner upper surface 41a where dryout is most likely to occur.

Furthermore, in this embodiment , as described above, the partition plate 44 is provided throughout the entire storage space 11, thereby reliably preventing the refrigerant gas 1a generated in the lower space 11b from collecting on the interior upper surface 41a of the storage space 11. Furthermore, the partition plate 44 has a first communication passage 45 that penetrates the partition plate 44 and connects the upper space 11a and the lower space 11b in an area that vertically overlaps with the through-hole 12a in the upper surface 12, allowing the refrigerant gas 1a in the lower space 11b to pass through the first communication passage 45 and move toward the condenser 20. Therefore, there is no need to form a passage in the boiling portion 10 separate from the partition plate 44 for moving the refrigerant gas 1a in the lower space 11b to the condenser 20, thereby simplifying the structure of the boiling-type cooler.

Furthermore, in the present embodiment , as described above, the second communication passage 46 that connects the upper space 11a and the lower space 11b is formed at the lower end E1 of the storage space 11. This allows the refrigerant liquid 1b to move through the second communication passage 46, even when the storage space 11 is partitioned into the upper space 11a and the lower space 11b. This prevents the refrigerant liquid 1b from being unevenly contained in either the upper space 11a or the lower space 11b, and allows the amount of refrigerant liquid 1b contained to be uniform between the upper space 11a and the lower space 11b. Furthermore, in the present embodiment , the second communication passage 46 interconnects the four refrigerant passages 42e in the lower space 11b and the four refrigerant passages 41e in the upper space 11a, thereby suppressing variation in the amount of refrigerant liquid 1b contained among the individual refrigerant passages.

Furthermore, in this embodiment , as described above, the condensing section 20 is provided to extend upward from the upper surface 12 of the boiling section 10 and has the flow passage 22 for the external fluid 2 that penetrates the condensing section 20 in the horizontal direction. Therefore, even if the boiling section 10 is tilted diagonally downward, the external fluid 2 can be sent horizontally to the condensing section 20 extending in the vertical direction. Therefore, in a configuration in which the refrigerant gas 1a in the condensing section 20 is condensed by forced cooling that sends the external fluid 2 using the driving source (blower 3), it is not necessary to tilt the driving source or the flow passage for the external fluid 2 in accordance with the inclination of the boiling section 10. Therefore, when the boiling type cooler 100 is combined with an external device, the boiling type cooler 100 can be easily adapted to the external device.

[ Reference example ]
9 to 11, the configuration of a boiling type cooler 200 (hereinafter referred to as cooler 200) according to a reference example of the present invention will be described. In this reference example , unlike the above embodiment in which a partition plate 44 is provided in the accommodation space 11 of the boiling part 10, an example in which a partition plate 44 is not provided in the accommodation space 11 of the boiling part 10 will be described.

In the reference example , the same components as those in the above embodiment are designated by the same reference numerals and their description is omitted. In particular, in the reference example , the external shape of the boiling section 10, the configurations of the condensing section 20 and the connecting section 30, other than the internal structure of the boiling section 10, are the same as those in the above embodiment shown in FIG. 1 . As shown in FIG. 12 , in the reference example , the boiling section 10 is also provided so as to extend obliquely downward from the connecting portion (connecting section 30) with the condensing section 20, and is inclined downward by an angle θ with respect to the horizontal direction (Y direction). Below, only the internal structure of the boiling section 10 will be described.

As shown in FIG. 9 , in the reference example , a partition plate 44 is not provided in the storage space 11 of the boiling portion 10. That is, the storage space 11 is not divided into an upper space 11a and a lower space 11b, but is a continuous space as a whole. As shown in FIG. 10 , the storage space 11 is divided by an inner upper surface 41a of the first member 41, an inner lower surface 42a of the second member 42, side wall portions 41c of the first member 41 and side wall portions 42c of the second member 42, a cover member 43 at one end E1 (see FIG. 9 ), and a cover member 43 at the other end E2 (see FIG. 9 ). As in the above embodiment, the storage space 11 is divided into four refrigerant passages by three partition walls 41d, 42d. Because a partition plate 44 is not provided, each refrigerant passage is formed from the inner lower surface 42a to the inner upper surface 41a and has a height equal to the height H of the storage space 11.

In the reference example , since the partition plate 44 is not provided, the case member 40 does not have to be configured with two members, the first member 41 and the second member 42. For example, the cylindrical case member 40 in which the first member 41 and the second member 42 are integrated may be formed as a single member by extrusion molding.

The other configurations of the reference example are the same as those of the above embodiment.

(Cooler operation)
11 , in the reference example , as in the above embodiment, the boiling portion 10 is inclined downward at an angle θ, and the liquid level 1c of the refrigerant 1 is located at a height that is the upper end of the installation area. Therefore, the inner upper surface 41a of the upper space 11a is always in contact with the refrigerant liquid 1b.

In the reference example , refrigerant gas 1a generated near inner lower surface 42a of storage space 11 by heat from heating element HS provided on lower surface 13 moves toward inner upper surface 41a without being blocked. Therefore, in the reference example , both refrigerant gas 1a generated on the inner upper surface 41a side and refrigerant gas 1a generated on the inner lower surface 42a side move along inner upper surface 41a toward other end E2. Because inner upper surface 41a is inclined upward at angle θ toward other end E2, refrigerant gas 1a is prevented from stagnating on inner upper surface 41a without moving.

When the refrigerant gas 1a reaches the position where the through-hole 12a is formed, the refrigerant gas 1a passes through the through-hole 12a and moves into the connecting portion 30. Other operations of the cooler 100 are the same as those of the above embodiment.

(Effects of the Reference Example )
In the reference example , as in the above embodiment, the boiling portion 10 is provided so as to extend obliquely downward from the connection portion 30 with the condensation portion 20, so that the refrigerant liquid 1b can be continuously contacted with the inner upper surface 41a of the accommodation space 11, and the refrigerant gas 1a can be prevented from excessively accumulating on the inner upper surface 41a. As a result, sufficient cooling performance can be exerted on the heating element HS placed on the upper surface 12 of the boiling portion 10, so that the heating element HS can be placed on not only the lower surface 13 but also the upper surface 12 of the boiling portion 10, thereby enabling the installation area of the heating element HS to be increased even in a horizontal boiling type cooler 100.

Other effects of the reference example are similar to those of the above embodiment.

[Example]
Next, the results of experiments conducted to confirm the effects of the cooler 100 of the above embodiment and the cooler 200 of the reference example will be described.

(Structure of boiling part)
In the examples, the cooling performance was measured under the same operating conditions for the cooler 100 of the above embodiment and the cooler 200 of the reference example . That is, as variations in the structure of the boiling part 10, the cooling performance was measured for two types of boiling parts, one with a partition plate 44 ( the above embodiment) and one without a partition plate 44 ( reference example ).

(tilt angle)
The cooling performance was measured under a number of conditions for the angle θ of the boiling portion 10. Specifically, the measurements were performed under three conditions: θ = 5 degrees, θ = 10 degrees, and θ = 0 degrees (horizontal) as shown in Fig. 12 as a comparative example.

(Operating conditions)
Furthermore, assuming that the heat generation amount of the heat generating element HS changes during actual operation, measurements were performed under a number of heat generation conditions. Specifically, the heat generation amount during rated operation assumed for the heat generating element HS made of a power module was set to 100%, and measurements were performed under three conditions: 50%, 100%, and 150%.

Therefore, cooling performance was measured for six configurations, combining two types of structures, with and without a partition plate, and three different inclination angles θ = 10 degrees, 5 degrees, and 0 degrees (0 degrees is the comparative example), under three operating conditions: 50%, 100%, and 150%.

Figures 13 to 15 are graphs showing the results of cooling performance measurements. Figures 13 to 15 show the results of measurements under heat generation conditions of 50%, 100%, and 150%, respectively. The horizontal axis of each graph in Figures 13 to 15 indicates the temperature measurement location. The temperature measurement locations represent six measurement locations set at intervals along the E direction in the installation area of the heating element HS in the boiling section 10. Within the installation area, measurement location 1 is closest to one end E1, and measurement location 6 is closest to the other end E2. The vertical axis of each graph indicates the difference value ΔT [K] between the mounting surface temperature of the heating element HS and the internal refrigerant temperature at each temperature measurement location. Because the heating element HS is installed on both the upper surface 12 and the lower surface 13, measurements are obtained for both the upper surface 12 and the lower surface 13 for the same temperature measurement location. The smaller the difference value ΔT, the higher the cooling performance, and the smaller the variation in the difference value ΔT at each temperature measurement location, the less localized performance fluctuations there are (the more stable the cooling performance). Each graph shows a reference line (thick line) that indicates the design value (theoretical value) of the difference value ΔT, calculated from the specifications of the boiling portion 10 and the set value of the heat generation amount of the heating element HS, without taking into account the behavior of the refrigerant gas 1a, as a guide for evaluating cooling performance. The value of the reference line varies depending on the heat generation amount conditions (50%, 100%, 150%).

Figure 16 shows a graph summarizing the graphs in Figures 13 to 15. The vertical axis in Figure 16 is the difference value ΔT [K], the same as in Figures 13 to 15. The horizontal axis represents the experimental conditions, showing the values for the top and bottom surfaces for six configurations that combine the presence or absence of a partition plate and the inclination angle θ. In Figure 16, the measurement results for a 50% heat generation amount (see Figure 13), a 100% heat generation amount (see Figure 14), and a 150% heat generation amount (see Figure 15) are shown with different hatching. Each measurement result is shown as a bar graph indicating the range between maximum and minimum ΔT values at six temperature measurement locations. The lower the plotted bar, the lower the ΔT value, and the shorter the bar, the smaller the difference between the maximum and minimum ΔT values.

(Comparison of tilt angles)
The effect of the tilt angle on cooling performance will be examined with reference to Figures 13 to 15. Plots A1, A2, and A3 represent the measurement results for the upper surface 12 of the boiling portion 10 with a partition plate, with θ = 10 degrees, 5 degrees, and 0 degrees. Plots A1 and A2, where the boiling portion 10 is tilted, are located lower than plot A3, which is a comparative example. Furthermore, plots A1 and A2 have smaller variations in ΔT than plot A3.

Plots A4, A5, and A6 represent the measurement results for the bottom surface 13 of the boiling section 10 with the partition plate at θ = 10 degrees, 5 degrees, and 0 degrees. These measurement results for the bottom surface 13 do not differ as greatly as the measurement results for the top surface 12 (A1 to A3).

Plots B1, B2, and B3 represent the measurement results for the upper surface 12 of the boiling section 10 without a partition plate, with θ = 10 degrees, 5 degrees, and 0 degrees. Plots B1 and B2, where the boiling section 10 is tilted, are located lower than plot B3, which is a comparative example. Furthermore, plots B1 and B2 have smaller variations in ΔT than plot B3.

Plots B4, B5, and B6 represent the measurement results for the bottom surface 13 of the boiling section 10 with the partition plate at θ = 10 degrees, 5 degrees, and 0 degrees. The measurement results for the bottom surface 13 do not differ as greatly as the measurement results for the top surface 12 (B1 to B3).

Focusing on the measurement results for the upper surface 12, the measurement results for θ=10 degrees and θ=5 degrees (A1, A2, B1, B2) consistently have ΔT values near the reference line in Figures 13 to 15. In contrast, the measurement results for θ=0 degrees (A3, B3) using the comparative example have ΔT values above the reference line in Figures 13 to 15, and also deviate significantly from the measurement results for θ=10 degrees and θ=5 degrees (A1, A2, B1, B2). The measurement results for θ=10 degrees and θ=5 degrees on the upper surface 12 (A1, A2, B1, B2) have ΔT values that are equal to or smaller than the measurement results for θ=10 degrees and θ=5 degrees on the lower surface 13 (A4, A5, B4, B5).

From this, it was confirmed that by tilting the boiling portion 10 diagonally downward from the horizontal direction, as in the above embodiment and reference example , the cooling performance on the upper surface 12 can be improved, and cooling performance on the upper surface 12 that is equal to or greater than that of the lower surface 13 can be obtained.

Furthermore, in Figure 15, which shows conditions with high heat generation, the ΔT value for the measurement results (A2, B2) at θ = 5 degrees is large, and the ΔT variation between each temperature measurement position is large. In contrast, the measurement results (A1, B1) at θ = 10 degrees show ΔT values below the reference line at all temperature measurement positions, indicating small variation. This tendency is not seen at 50% heat generation (Figure 13) or 100% heat generation (Figure 14). This confirms that increasing the tilt angle θ is effective in maintaining cooling performance (expanding the allowable range of heat generation), especially under high-load conditions where heat generation is high.

(Comparison with and without partition)
Next, we consider the effect of the presence or absence of a partition on cooling performance. When θ = 10 degrees and the case with a partition (A1) on the top surface 12 is compared with the case without a partition (B1), the case with the partition has the same or smaller ΔT value.

When comparing the case where the partition plate is provided (A2) and the case where the partition plate is not provided (B2) on the top surface 12 at θ = 5 degrees, the ΔT value is smaller with the partition plate. In particular, under high load conditions with a heat generation rate of 150%, the ΔT value is significantly reduced by providing the partition plate 44. In this way, it was confirmed that providing the partition plate 44 can improve cooling performance (reducing the ΔT value). Furthermore, the results of the study on the inclination angle θ confirmed that cooling performance under high load conditions can be significantly improved by increasing the inclination angle θ, but that it is possible to improve cooling performance by providing the partition plate 44 when the angle θ cannot be made sufficiently large.

[Modification]
It should be noted that the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

For example, in the above embodiment , the heating element HS is a power module used in a power conversion device, but the present invention is not limited to this. In the present invention, the heating element may be any object. The heating element may be a semiconductor chip such as a CPU or an electronic circuit mounted on an electronic device such as a server.

In the above embodiment , the condenser section 20 is provided to extend upward from the upper surface 12 of the boiling section 10, and has the flow passage 22 for the external fluid 2 that passes horizontally through the condenser section 20. However, the present invention is not limited to this. In the present invention, the condenser section 20 may be provided to extend in a direction other than upward, and the flow passage 22 for the external fluid 2 may be provided to pass through the condenser section 20 in a direction other than horizontal.

For example, in the example shown in Figure 17, the condenser section 20 is arranged to protrude horizontally (Y direction) relative to the connection section 30 that rises upward from the boiling section 10. The flow path 22 for the external fluid 2 is arranged to penetrate the condenser section 20 in the vertical direction (Z direction). The external fluid 2 passes upward through the flow path 22 by, for example, a blower 3 arranged below the condenser section 20. Conversely, the external fluid 2 may also pass downward through the flow path 22 by a blower arranged above the condenser section 20.

Furthermore, in the above embodiment , an example was shown in which a connection portion 30 was provided to connect the condenser portion 20 and the boiling portion 10, but the present invention is not limited to this. In the present invention, the condenser portion 20 may be directly connected to the upper surface 12 of the boiling portion 10. That is, a configuration may be adopted in which the lower end of the storage space 21a of the condenser portion 20 communicates with the through-hole 12a in the upper surface 12 of the boiling portion 10, and the wall portion 24 of the condenser portion 20 is joined to the upper surface 12 of the boiling portion 10 so that the storage space 21a and the storage space 11 form a closed space.

In the above embodiment , the boiling portion 10 and the condensing portion 20 are connected by a single passage (connection portion 30), but the present invention is not limited to this. For example, the present invention may be configured such that the circulation path of the refrigerant 1 is configured in a loop shape by providing a first passage through which the refrigerant gas 1a moving to the condensing portion 20 passes and a second passage through which the refrigerant liquid 1b moving to the boiling portion 10 passes.

In the above embodiment , the angle θ of the boiling portion 10 is 5 degrees and 10 degrees, but the present invention is not limited to this. The angle θ may be 5 degrees or more and less than 10 degrees, or may be an angle greater than 10 degrees. For example, the example shown in FIG. 18 shows an example where θ=30 degrees.

In the above embodiment , the installation area on the upper surface 12 of the boiling portion 10 and the installation area on the lower surface 13 are located at the same position and in the same range (length L1) in the E direction. However, the present invention is not limited to this. The installation area on the upper surface 12 and the installation area on the lower surface 13 may be located at different positions and in different ranges. For example, in the example shown in FIG. 18 , two installation areas are located on the upper surface 12 of the boiling portion 10, and three installation areas are located on the lower surface 13. In particular, the installation area on the other end E2 of the lower surface 13 is located in a position aligned with the condenser portion 20 in the Z direction. This modified configuration allows for the installation of a larger number of heating elements HS.

In the above embodiment , the liquid level 1c of the refrigerant 1 is set within the installation area of the heating element HS on the upper surface 12 of the boiling portion 10 when the cooler is not operating, but the present invention is not limited to this. In the present invention, the liquid level 1c may be set at a position above the installation area of the heating element HS on the upper surface 12. With this configuration, the entire area of the inner upper surface 41a of the accommodation space 11 facing the installation area of the heating element HS (the area directly below the heating element HS) can be brought into contact with the refrigerant liquid 1b.

Furthermore, in the above embodiment, an example has been shown in which the partition plate 44 is provided throughout the entire storage space 11, but the present invention is not limited to this. In the present invention, the partition plate 44 may be provided locally in a part of the storage space 11. For example, in the example shown in Fig. 19, the partition plate 44 is provided in an area OA that overlaps the installation area of the heating element HS on the upper surface 12 in the thickness direction of the boiling portion 10, and is not provided in other areas. Even in this case, the partition plate 44 can prevent the refrigerant gas 1a from the lower space 11b from collecting on the inner upper surface 41a directly below the installation area of the heating element HS on the upper surface 12.

In the above embodiment, the height h1 of the upper space 11a and the height h2 of the lower space 11b are equal to each other, but the present invention is not limited to this. In the present invention, the height h1 of the upper space 11a and the height h2 of the lower space 11b may be different from each other. For example, the height h1 of the upper space 11a and the height h2 of the lower space 11b may be set depending on the heat generation amount of the heat generating element HS installed on the upper surface 12 and the heat generation amount of the heat generating element HS installed on the lower surface 13.

In the above embodiment, the partition plate 44 is formed only with the first communication passage 45 formed by a through-hole and the second communication passage 46 formed by a notch, and no other through-holes or notches are formed therein. However, the present invention is not limited to this. In the present invention, the partition plate 44 may be formed with through-holes or notches to adjust the amount of refrigerant gas 1a passing through. For example, in the example shown in FIG. 20 , the partition plate 44 is formed with multiple through-holes 441. The through-holes 441 are formed in an area that overlaps the installation area of the heating element HS on the upper surface 12 in the thickness direction of the boiling portion 10. The through-holes 441 are configured to allow a portion of the refrigerant gas 1a generated in the lower space 11b to pass into the upper space 11a. The through-holes 441 are formed to a size that allows an appropriate amount of refrigerant gas 1a to pass through the through-holes 441. This allows the ratio of the amount of refrigerant liquid 1b to the amount of refrigerant gas 1a on the internal upper surface 41a to be adjusted, and under conditions where the refrigerant liquid 1b and refrigerant gas 1a are present in an appropriate ratio, the cooling performance on the upper surface 12 side can be effectively improved.

In the above embodiment, the first communication passage 45 is formed by a through hole formed in the partition plate 44. However, the present invention is not limited to this. For example, when the partition plate 44 is partially provided within the accommodation space 11 as shown in FIG. 19 , the upper space 11a and the lower space 11b communicate with each other in the area where the partition plate 44 is not provided, and therefore the first communication passage 45 need not be provided. When the partition plate 44 is provided over the entire accommodation space 11, the first communication passage 45 may be formed by a notch formed in the other end of the partition plate 44, similar to the second communication passage 46. Furthermore, as shown in FIG. 21 , for example, a recess 43a spanning the upper space 11a and the lower space 11b may be formed in the cover member 43 that closes the other end E2 of the boiling portion 10, and the recess 43a may serve as the first communication passage 45.

In the above embodiment, the second communication passage 46 is formed by a notch formed in the partition plate 44, but the present invention is not limited to this. For example, the second communication passage 46 may be formed by a through-hole formed in the partition plate 44, similar to the first communication passage 45. Also, as shown in FIG. 21 , for example, a recess 43b spanning the upper space 11a and the lower space 11b may be formed in the cover member 43 that closes one end E1 of the boiling portion 10, and the recess 43b may constitute the second communication passage 46. In the present invention, the second communication passage 46 does not necessarily have to be provided.

In the above embodiment, the upper space 11a and the lower space 11b are each divided into a plurality of (four) refrigerant passages 41e and 42e by the partition walls 41d and 42d, respectively , but the present invention is not limited to this. In the present invention, the accommodation space 11 (the upper space 11a and the lower space 11b) does not have to be divided into a plurality of refrigerant passages.

REFERENCE SIGNS LIST 1 Refrigerant 1a Refrigerant gas 1b Refrigerant liquid 1c, 1d Liquid surface 2 External fluid 10 Boiling portion 11 Storage space 11a Upper space 11b Lower space 12 Upper surface 12a Through hole 13 Lower surface 20 Condenser portion 22 Flow passage 30 Connection portion 44 Partition plate 45 First communication passage 46 Second communication passage 100, 200 Cooler (boiling type cooler)
E1 One end E2 Other end HS Heating element θ Inclination angle

Claims (5)

a boiling portion having a storage space for storing a refrigerant and boiling the refrigerant by heat exchange with a heating element;
a condensing section that is in communication with the boiling section and that condenses the refrigerant gas from the boiling section by heat exchange with an external fluid,
the boiling portion is formed in a plate-like shape having an upper surface and a lower surface on which the heating element is installed, and is provided so as to extend obliquely downward from a connection portion with the condensing portion , and further includes a partition plate that divides the storage space into an upper space adjacent to the upper surface and a lower space adjacent to the lower surface,
the condensation section is provided to extend upward from the upper surface of the boiling section,
a through-hole that communicates the storage space with the condenser portion is formed on the upper surface of the boiling portion;
the through-hole is configured to allow the refrigerant gas to flow into the condenser portion and allow the condensed refrigerant to flow into the accommodation space ,
The partition plate is provided across the entire storage space, and in a region that overlaps vertically with the through hole on the upper surface, has a first communication passage that passes through the partition plate to connect the upper space and the lower space . The boiling type cooler according to claim 1, wherein the boiling portion is inclined so that the liquid level of the refrigerant is located within the installation area of the heating element on the upper surface or above the installation area of the heating element. The boiling type cooler according to claim 2, wherein the boiling portion is inclined at an angle of 5 degrees or more and less than 45 degrees relative to the horizontal. 2. The boiling type cooler according to claim 1 , wherein a second communication passage that connects the upper space and the lower space is formed at one end of the accommodation space located on the lower side. The boiling type cooler according to claim 1, wherein the condenser section has a flow passage for the external fluid that passes horizontally through the condenser section.