Electronic control device

Abstract

The purpose of the present invention is to provide an electronic control device capable of suppressing deterioration in performance of cooling an electronic component by suppressing exposure of the electronic component from a liquid coolant even when a moving body vibrates or tilts.　An electronic control device according to the present invention comprises: a circuit board 10 on which an electronic component 11 is mounted; a housing 2 which houses the circuit board 10 and a liquid coolant 20; a cooler 30 which is arranged in an upper region inside the housing 2; and a wall part 40 which extends from a bottom part toward the cooler 30 inside the housing 2 and divides the inside of the housing 2 into a first region 61 and a second region. The circuit board 10 is immersed in the liquid coolant 20 in the first region 61. Inside the housing 2, at least two flow channels 51 that provide communication between the first region 61 and the second region 62 are formed. The channels 51 are each provided with a valve 50 that allows flow of the liquid coolant 20 from the second region 62 to the first region 61 and restricts flow of the liquid coolant 20 from the first region 61 to the second region 62.

Description

Electronic control unit

[0001] The present invention relates to an electronic control device.

[0002] In electronic control devices used in vehicles and other devices, the processing speed of arithmetic circuits such as central processing units (CPUs) mounted on circuit boards is increasing in order to improve the performance of the devices, and the heat generated by these arithmetic circuits (electronic components) is also increasing. Well-known methods for cooling heat-generating electronic components include air-cooling and water-cooling. These cooling methods involve applying air or cooling water at a temperature lower than the heat generated by the electronic components to cooling fins or other devices connected to the electronic components. Another cooling method is immersion boiling cooling, in which heat-generating electronic components are directly immersed in a liquid refrigerant, and the heat is then vaporized by the liquid refrigerant, thereby removing the heat.

[0003] For example, Patent Document 1 discloses a technology for cooling a semiconductor device, which is a heat-generating body, from two directions using two cooling means. Patent Document 1 discloses a technology that includes a cooler that circulates cooling water in a coolant container and a liquid coolant that boils at a predetermined temperature, where one side of the semiconductor device is cooled by contacting the cooler, and the other side is immersed in the liquid coolant and cooled by boiling.

[0004] Patent Document 2 discloses an electrical device in which a heat-generating component is immersed in a liquid refrigerant, the liquid refrigerant stored inside a housing is vaporized by the heat generated by the heat-generating component, and the vaporized refrigerant is cooled by a heat exchange mechanism disposed above the housing. In Patent Document 2, a guide member extending in the vertical direction is provided between the side wall of the housing and the heat-generating component, and a passage through which the vaporized refrigerant can flow is formed above the guide member, and a flow path through which the liquid refrigerant can flow is formed below the guide member. With the above configuration in Patent Document 2, the guide member separates the boiling of the liquid refrigerant, the condensation of the vaporized refrigerant, and the reflux of the condensed liquid refrigerant, thereby regulating the flow of the refrigerant.

[0005] In electronic control devices mounted on moving objects such as vehicles, there is a problem with applying the immersion boiling cooling method described in Patent Documents 1 and 2. The problem is that the liquid level of the liquid refrigerant placed inside the device may fluctuate or tilt due to vibration or tilting of the moving object, which may expose the heat-generating electronic components from the liquid refrigerant and result in insufficient cooling performance.

[0006] To solve this problem, Patent Document 3 discloses a structure that includes a cooling tank in which a heating element is stored, a liquid storage tank, and a connecting part that connects these, and that has a liquid level control part that prevents the heating element from being exposed from the liquid refrigerant when the cooling tank is tilted.

[0007] JP 2008-227150 A, JP 2022-179901 A, JP 2023-149859 A

[0008] In electronic control devices mounted on moving objects such as vehicles, the level of the liquid refrigerant placed inside the electronic control device fluctuates when the moving object vibrates or when the moving object travels over an incline such as a slope, causing the electronic components to be cooled to become exposed. One way to prevent this is to increase the amount of liquid refrigerant placed inside the electronic control device so that the electronic components are not exposed even when the liquid refrigerant level fluctuates, but this has the problem of increasing the weight of the electronic control device.

[0009] Furthermore, to improve cooling performance, it is necessary to efficiently circulate the liquid refrigerant that immerses the electronic components, the liquid refrigerant boils due to heat generated by the electronic components, the boiled refrigerant is condensed by the cooler, and the condensed refrigerant is returned to immerse the electronic components again.

[0010] Patent Documents 1 and 2 do not disclose a means for solving the problem of fluctuations in the liquid refrigerant level due to vibration or tilting of the moving body, and Patent Document 3 discloses a means for solving the problem of fluctuations in the liquid refrigerant level, but does not disclose a means for efficiently circulating the liquid refrigerant through immersion, boiling, and condensation.

[0011] The object of the present invention is to provide an electronic control device that can prevent electronic components from being exposed to liquid refrigerant even when the moving body vibrates or tilts, and can prevent a decrease in the cooling performance of the electronic components.

[0012] In order to achieve the above object, the present invention provides an electronic control device to be mounted on a moving body, comprising: a circuit board on which electronic components are mounted; a housing that houses the circuit board and a liquid refrigerant; a cooler arranged at an upper part within the housing; and a wall extending from the bottom of the housing toward the cooler and dividing the housing into a first area and a second area, wherein the circuit board is immersed in the liquid refrigerant within the first area, and at least two flow paths are formed within the housing that connect the first area and the second area, and the flow paths are equipped with valves that allow the liquid refrigerant to flow from the second area toward the first area and limit the flow of the liquid refrigerant from the first area toward the second area.

[0013] According to the present invention, an electronic control device can be provided that prevents electronic components from being exposed to the liquid refrigerant even when the moving body vibrates or tilts, thereby preventing a decrease in the cooling performance of the electronic components.

[0014] 1. A front cross-sectional view of a conventional electronic control device 1. 2. A side cross-sectional view of a conventional electronic control device 1. 3. A front cross-sectional view of a conventional electronic control device 1 when the liquid level of the liquid refrigerant 20 is inclined. 4. A side cross-sectional view of a conventional electronic control device 1 when the liquid level of the liquid refrigerant 20 is inclined. 5. A front cross-sectional view of an electronic control device 1 according to a first embodiment of the present invention, as viewed from a normal direction of a circuit board 10. 6. A diagram showing a state in which the liquid level of the liquid refrigerant 20 is inclined with respect to the bottom surface of a housing 2 in the electronic control device 1 shown in FIG. 5. 7. An enlarged bottom view of an electronic control device 1 according to a first embodiment of the present invention. 8. A diagram showing a state in which the liquid level of the liquid refrigerant 20 is inclined for a long period of time. 9. A side cross-sectional view of an electronic control device 1 according to a first embodiment of the present invention, as viewed from a horizontal tangential direction of a circuit board 10. 10. An external perspective view of an electronic control device 1 according to a second embodiment of the present invention. 11. A front cross-sectional view of an electronic control device 1 according to a second embodiment of the present invention, as viewed from a normal direction of a circuit board 10. 12. A cross-sectional view of an electronic control device 1 according to a third embodiment of the present invention. 13. A cross-sectional view taken along line XIII-XIII of plane 71 shown in FIG. 12. 14. A cross-sectional view taken along line XIV-XIV of FIG. 13. 26A and 26B are cross-sectional views taken along line XV-XV in FIGS. 13 and 14 . A cross-sectional view according to comparative example 1 compared with the structure of FIG. 15 . A cross-sectional view according to comparative example 2 compared with the structure of FIG. 15 . A cross-sectional view according to a modified example of embodiment 3. A cross-sectional view according to a modified example of embodiment 3. A front cross-sectional view of an electronic control device 1 according to embodiment 4 of the present invention, as seen from the normal direction of the circuit board 10. A cross-sectional view according to a modified example of embodiment 4. A front cross-sectional view of an electronic control device 1 according to embodiment 5 of the present invention, as seen from the normal direction of the circuit board 10. An enlarged bottom view of an electronic control device 1 according to embodiment 5 of the present invention. A front cross-sectional view of an electronic control device 1 according to embodiment 6 of the present invention, as seen from the normal direction of the circuit board 10. A cross-sectional view according to modified example 1 of embodiment 6. An external perspective view of an electronic control device 1 according to modified example 2 of embodiment 6. A cross-sectional view taken along line XXVII-XXVII taken along plane 71 shown in FIG. 26A and 26B are cross-sectional views according to modified example 3 of embodiment 6. A cross-sectional view taken along line XXIX-XXIX taken along plane 71 shown in FIG. 28A and 28B are cross-sectional views taken along line XXIX-XXIX in FIG. A partially enlarged cross-sectional view of a wall portion 40 of an electronic control device 1 according to embodiment 7 of the present invention. A cross-sectional view according to a modified example of embodiment 7.

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In principle, identical elements are designated by the same reference numerals in all drawings. Furthermore, descriptions of parts having the same functions will be omitted. The configurations described below are merely examples, and are not intended to limit the embodiments of the present invention to the specific embodiments described below. In each drawing, the upper side of the page is defined as "top" and the lower side as "bottom." Furthermore, in a front view of the electronic control device as seen from the normal direction of the circuit board 10, the left side is defined as "left," the right side as "right," the near side as "front," and the far side as "rear."

[0016] First, a conventional electronic control device will be described with reference to FIGS. 1 to 4. FIG. 1 is a front cross-sectional view of a conventional electronic control device 1. In FIG. 1, the electronic control device has an internal space defined by a housing 2 and a cover 3. The housing 2 includes a circuit board 10, a liquid refrigerant 20, and a cooler 30. Electronic components 11 are mounted on the surface of the circuit board 10. The heat-generating electronic components 11 are immersed in an insulating liquid refrigerant 20. The boiling point of the liquid refrigerant is lower than the heat generation temperature of the electronic components. Cooling water 31, which is cooled outside the electronic control device 1 and has a temperature lower than the boiling point of the liquid refrigerant, flows through the cooler 30. The liquid refrigerant 20 is heated and boils due to the heat generated by the electronic components 11. The boiling boiling refrigerant 21 is cooled by the cooler 30 located above the housing 2. The cooled boiling refrigerant 21 is condensed into condensed refrigerant 22 and returns to the liquid refrigerant 20. By repeating this boiling and condensing process, the heat generated by the electronic components 11 is transferred to the cooling water and discharged to the outside of the electronic control device 1 .

[0017] Fig. 2 is a side cross-sectional view of a conventional electronic control device 1. As shown in Fig. 2, four circuit boards 10 are arranged inside a housing 2, and electronic components 11 are mounted on each circuit board 10. In Fig. 2, similar to Fig. 1, a liquid refrigerant 20 is heated and boiled by the electronic components 11, and the boiled boiling refrigerant 21 is cooled by a cooler 30 installed above the housing 2, and the condensed refrigerant 22 returns to the liquid refrigerant 20.

[0018] 1 and 2 are schematic diagrams showing the state in which the liquid level of the liquid refrigerant 20 placed inside the electronic control device 1 is horizontal. Figures 3 and 4 are cross-sectional views of the electronic control device 1 in a state in which the liquid level of the liquid refrigerant 20 is inclined.

[0019] 3 is a front cross-sectional view of the conventional electronic control device 1 when the liquid level of the liquid refrigerant 20 is tilted. As shown in Fig. 3, the liquid level of the liquid refrigerant 20 is higher on the right side and lower on the left side relative to the bottom surface of the housing 2. When the liquid level of the liquid refrigerant 20 is tilted, a portion of the electronic component 11 is exposed from the liquid refrigerant 20, and the cooling performance of the electronic component 11 at the exposed portion 23 is deteriorated.

[0020] 4 is a side cross-sectional view of a conventional electronic control device 1 when the liquid level of liquid refrigerant 20 is tilted. As shown in Fig. 4, the liquid level of liquid refrigerant 20 is higher on the front side of housing 2 and lower on the rear side. When the liquid level of liquid refrigerant 20 is tilted, part of electronic component 11 is exposed from liquid refrigerant 20, and the cooling performance of electronic component 11 deteriorates at exposed portion 23.

[0021] One possible method for preventing exposure of electronic components 11 from liquid refrigerant 20 due to the tilt of the liquid surface of liquid refrigerant 20 shown in Figures 3 and 4 is to increase the amount of liquid refrigerant 20 placed inside electronic control device 1, but this has the problem of increasing the weight of electronic control device 1.

[0022] Hereinafter, an embodiment of an electronic control device according to the present invention will be described with reference to the drawings. In each drawing, common members are given the same reference numerals.

[0023] 5 is a front cross-sectional view of the electronic control device 1 according to the first embodiment of the present invention, as viewed from the normal direction of the circuit board 10. In FIG. 5, the liquid surface of the liquid refrigerant 20 is horizontal.

[0024] 5, the electronic control device has a housing 2 having an open portion at the top and a space provided inside by a cover 3 covering the open portion. The housing 2 contains a circuit board 10, a liquid refrigerant 20, and a cooler 30.

[0025] The circuit board 10 is arranged with its plane oriented vertically and is connected to other electronic control devices and the like via connectors and harnesses (not shown). Electronic components 11 are mounted on the surface of the circuit board 10. The heat-generating electronic components 11 are immersed in an insulating liquid coolant 20 having a boiling point lower than the heat generation temperature of the electronic components. Examples of the liquid coolant 20 include fluorine-based inert liquids such as perfluoropolyether (PFPE), perfluorocarbon (PFC), and hydrofluoroether (HFE), as well as silicone oil.

[0026] The housing 2 is formed with walls 40 (40a, 40b) extending from the bottom surface (lower side) of the housing 2 toward the cooler 30 above. In FIG. 5 , the wall 40 is formed on the left side in the longitudinal direction of the circuit board 10, and the wall 40b is formed on the right side. However, the wall 40 is also formed on the front and rear sides in the longitudinal direction of the circuit board 10 in the same manner. The front and rear walls may be configured such that the ends of the left wall 40a and the right wall 40b are in contact with the inner walls of the housing 2. The left wall 40a and the right wall 40b are arranged to face each other, and the front wall and the rear wall are arranged to face each other.

[0027] The space inside the housing 2 is divided by the wall 40 into a first area 61 (shown by a dashed line) in which the circuit board 10 is housed, and a second area 62 (shown by a dotted line) formed between the wall 40 and the wall surface of the housing 2.

[0028] The space formed between the liquid refrigerant 20 and the cover 3 inside the housing 2 is filled with gas resulting from boiling or vaporizing the liquid refrigerant 20 and with air remaining when the liquid refrigerant 20 is sealed in. The inside of the housing 2 may be placed in a low-pressure state such as a vacuum before the liquid refrigerant 20 is introduced.

[0029] A flow path 51a (first flow path) through which the liquid refrigerant 20 can flow between the first region 61 and the second region 62 is provided in the lower part of the wall portion 40a. Similarly, a flow path 51b (second flow path) through which the liquid refrigerant 20 can flow between the first region 61 and the second region 62 is provided in the lower part of the wall portion 40b.

[0030] Furthermore, the flow path 51a is provided with an openable / closable valve 50a (first valve) that allows the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restricts the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62. Similarly, the flow path 51b is provided with an openable / closable valve 50b (second valve) that allows the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restricts the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62. In FIG. 5 , the valves 50a and 50b are schematically shown as valves that have a fulcrum at their upper ends and open in an arc shape upward around the fulcrum. In this embodiment, at least two flow paths 51a and 51b that communicate between the first region 61 and the second region 62 are formed within the housing 2, and valves 50a and 50b are installed in the flow paths 51a and 51b, respectively.

[0031] Cooling water 31 cooled outside the electronic control device 1 to a temperature lower than the boiling point of the liquid refrigerant 20 circulates inside the cooler 30. The liquid refrigerant 20 is heated and boils due to heat generated by the electronic components 11, and the boiled boiling refrigerant 21 is cooled by the cooler 30 arranged above inside the housing 2, and the cooled boiling refrigerant 21 is condensed to become condensed refrigerant 22 and returns to the liquid refrigerant 20. The lower surface of the cooler 30 is inclined downward from the center position in the left-right direction toward the outside (periphery) in the left-right direction.

[0032] 5, the cooler 30 side of the wall portion 40a, 40b is provided with inclined portions 41a, 41b that are inclined so that the opposing wall portions 40a, 40b approach each other as they move toward the cooler 30 side (upward). As a result, the condensed refrigerant 22a that is condensed in the cooler 30 and falls onto the inclined portions 41a, 41b flows toward the liquid refrigerant 20 that has accumulated in the second region 62 along the inclination of the inclined portions 41a, 41b.

[0033] When the liquid level of the liquid refrigerant 20 pooled in the second region 62 becomes higher than the liquid level of the liquid refrigerant 20 in the first region 61, the liquid refrigerant 20 moves from the second region 62 toward the first region 61 through the flow paths 51a, 51b and the valves 50a, 50b provided in the walls 40a, 40b. This makes it possible for the wall 40 to separate the boiling refrigerant 21 generated in the first region 61 from the condensed refrigerant 22 condensed in the cooler 30, thereby enabling efficient cooling of the electronic components 11.

[0034] 5, the cooler 30 is inclined toward the side surface of the housing 2. This allows the condensed refrigerant 22b that is condensed in the cooler 30 and adheres to the surface of the cooler 30 to be guided toward the side surface of the housing 2.

[0035] With the above-described structure, the circulation of the liquid refrigerant 20 immersing the circuit board 10, the boiling refrigerant 21 boiled by the electronic components, and the condensed refrigerant 22 condensed in the cooler 30 can be separated by the walls 40a and 40b, thereby allowing the electronic components to be cooled efficiently.

[0036] Fig. 6 is a diagram showing a state in which the liquid level of the liquid refrigerant 20 is inclined with respect to the bottom surface of the housing 2 in the electronic control device 1 shown in Fig. 5. Fig. 7 is an enlarged view of the bottom of the electronic control device 1 according to the first embodiment of the present invention.

[0037] FIG. 6 shows a state in which the liquid level of the liquid refrigerant 20 is high on the right side and low on the left side. The function of the valves 50a and 50b at this time will be explained using FIG. 7 . Pressure from the liquid refrigerant 20 is applied to the valve 50b installed on the right wall 40b in the direction from the first region 61 to the second region 62, causing the valve 50b to close the flow path 51b. Therefore, the flow 20b of the liquid refrigerant 20 from the first region 61 to the second region 62 is prevented by the valve 50b in the flow path 51b. Meanwhile, pressure from the liquid refrigerant 20 is applied to the valve 50a installed on the left wall 40a in the direction from the second region 62 to the first region 61, causing the valve 50a to open the flow path 51a. This allows the flow 20a of the liquid refrigerant 20 from the second region 62 to the first region 61 in the flow path 51a.

[0038] As described above, in this embodiment, the function of valves 50a and 50b prevents the liquid refrigerant 20 from flowing out from the first region 61 to the second region 62 on the right side, while allowing the liquid refrigerant 20 to flow from the second region 62 on the left side into the first region 61. Therefore, even when the liquid level of the liquid refrigerant 20 tilts, the decrease in the liquid level of the liquid refrigerant 20 in the first region 61 can be suppressed, and exposure of the electronic components 11 to the liquid refrigerant 20 can be suppressed.

[0039] FIG. 8 shows a state in which the liquid level of the liquid refrigerant 20 remains tilted for a long period of time. When the liquid refrigerant 20 remains tilted for a long period of time, such as when a vehicle is parked on a slope, the condensed refrigerant 22 condensed in the cooler 30 accumulates unevenly in the second region 62 on the right side. As a result, the liquid level in the second region 62 on the right side rises, as shown by the liquid level 20c in FIG. 8 . When the liquid level in the second region 62 on the right side becomes higher than the liquid level in the first region 61, the force of the liquid refrigerant 20 from the second region 62 toward the first region 61 acts on the valve 50b. As a result, the valve 50b opens the flow path 51b, allowing the liquid refrigerant 20 to flow toward the first region 61. Therefore, even if the liquid level remains tilted, the liquid level of the liquid refrigerant 20 in the first region 61 does not continue to decrease.

[0040] 5 to 8, the first embodiment has been described using a front cross-sectional view of the electronic control device 1 when viewed from a normal direction of the circuit board 10. In Fig. 9, the first embodiment will be described using a side cross-sectional view of the electronic control device 1 when viewed from a horizontal tangential direction of the circuit board 10. Fig. 9 is a side cross-sectional view of the electronic control device 1 according to the first embodiment of the present invention when viewed from a horizontal tangential direction of the circuit board 10.

[0041] As shown in FIG. 9, four (a plurality of) circuit boards 10 are arranged in the front-to-rear direction inside the housing 2, and electronic components 11 are mounted on each circuit board 10.

[0042] In the housing 2, walls 40 (40c, 40d) extending from the bottom surface (lower side) of the housing 2 toward the cooler 30 are formed on the front and rear sides of the four circuit boards 10. In Fig. 9, as the walls 40, the wall 40c is formed on the front side of the circuit boards 10, and the wall 40d is formed on the rear side of the circuit boards 10. The front wall 40c and the rear wall 40d are arranged to face each other.

[0043] The space inside the housing 2 is divided by the walls 40c and 40d into a first area 61 (shown by a dashed line) in which the circuit board 10 is housed, and a second area 62 (shown by a dotted line) formed between the wall 40 and the wall surface of the housing 2.

[0044] A flow path 51c (third flow path) through which the liquid refrigerant 20 can flow between the first region 61 and the second region 62 is provided in the lower part of the wall portion 40c. Similarly, a flow path 51d (fourth flow path) through which the liquid refrigerant 20 can flow between the first region 61 and the second region 62 is provided in the lower part of the wall portion 40d.

[0045] Furthermore, the flow path 51c is provided with an openable / closable valve 50c (third valve) that allows the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restricts the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62. Similarly, the flow path 51d is provided with an openable / closable valve 50d (fourth valve) that allows the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restricts the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62.

[0046] 9, the liquid level of liquid refrigerant 20 is inclined relative to the bottom surface so that it is higher at the front side of housing 2 and lower at the rear side. As in the front cross-sectional views described with reference to FIGS. 5 to 8, front valve 50c closes flow path 51c, preventing the flow of liquid refrigerant 20 from first region 61 to second region 62. Meanwhile, valve 50d opens flow path 51, allowing the flow of liquid refrigerant 20 from second region 62 to first region 61. These actions suppress a drop in the liquid level of liquid refrigerant 20 in first region 61, preventing electronic components 11 from being exposed to liquid refrigerant 20.

[0047] Next, a second embodiment will be described with reference to Figures 10 and 11. Configurations common to the first embodiment are assigned the same reference numerals, and detailed descriptions thereof will be omitted. Figure 10 is an external perspective view of an electronic control unit 1 according to the second embodiment of the present invention. Figure 11 is a front cross-sectional view of the electronic control unit 1 according to the second embodiment of the present invention when viewed from the normal direction of the circuit board 10.

[0048] In this embodiment, the housing 2 is open at the front, and a cover 3 is provided on the front side of the open housing 2. A circuit board 10 is mounted inside the space formed by the housing 2 and the cover 3, and electronic components 11 are mounted on the circuit board 10. The circuit board 10 is connected to other electronic control devices and the like via connectors and harnesses (not shown). In addition, a cooling water channel 33 that serves as a cooler is formed integrally with the housing 2 at the top. Cooling water inlets and outlets 32 are attached to both ends of the cooling water channel 33 for circulating cooling water 31 between the outside of the electronic control device 1 and the cooling water channel 33. A liquid refrigerant 20 is placed inside the housing 2.

[0049] The housing 2 is formed with walls 40 (40a, 40b) extending from the bottom surface (lower side) of the housing 2 toward the cooling water channel 33. In FIG. 11 , the wall 40 is formed on the left side in the longitudinal direction of the circuit board 10, and the wall 40b is formed on the right side. One (front) end of the left wall 40a and the right wall 40b contacts the inner wall of the housing 2, and the other (rear) end of the left wall 40a and the right wall 40b contacts the inner wall of the cover 3. The interior of the housing 2 is provided with a first area 61 formed by the inner walls of the walls 40a, 40b, the rear inner wall of the housing 2, and the rear inner wall of the cover 3, and in which the circuit board 10 is stored, and a second area 62 located on the left and right outside of the first area 61, and formed by the left and right inner walls of the housing 2, the outer walls of the walls 40a, 40b, the rear inner wall of the housing 2, and the rear inner wall of the cover 3. In other words, the first region 61 and the second region 62 are divided by the walls 40a and 40b.

[0050] A flow path 51a (first flow path) through which the liquid refrigerant 20 can flow between the first region 61 and the second region 62 is provided in the lower part of the wall portion 40a. Similarly, a flow path 51b (second flow path) through which the liquid refrigerant 20 can flow between the first region 61 and the second region 62 is provided in the lower part of the wall portion 40b.

[0051] Furthermore, the flow path 51a is provided with an openable / closable valve 50a (first valve) that allows the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restricts the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62. Similarly, the flow path 51b is provided with an openable / closable valve 50b (second valve) that allows the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restricts the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62.

[0052] Cooling water 31 cooled outside the electronic control device 1 to a temperature lower than the boiling point of the liquid refrigerant 20 circulates inside the cooling water channel 33. The liquid refrigerant 20 is heated and boils due to heat generated by the electronic components 11, and the boiled boiling refrigerant 21 is cooled in the cooling water channel 33 located at an upper part inside the housing 2, and the cooled boiling refrigerant 21 is condensed to become condensed refrigerant and return to the liquid refrigerant 20. The cooling water channel 33 is inclined downward from the center position in the left-right direction outward in the left-right direction.

[0053] 11 , the wall portions 40a and 40b have inclined portions 41a and 41b on the cooling water passage 33 side, which are inclined so that the opposing wall portions 40a and 40b approach each other as they move toward the cooling water passage 33 (upward). As a result, the condensed refrigerant that is condensed in the cooling water passage 33 and falls onto the inclined portions 41a and 41b flows toward the liquid refrigerant 20 that has accumulated in the second region 62 along the slope of the inclined portions 41a and 41b.

[0054] 11 shows a case where the liquid level of the liquid refrigerant 20 is higher on the right side relative to the bottom surface of the housing 2. At this time, the right valve 50b closes the flow path 51b because pressure is applied from the first region 61 toward the second region 62, and no liquid refrigerant 20 flows from the first region 61 to the second region 62. On the other hand, the left valve 50a opens the flow path 51a because pressure is applied from the second region 62 toward the first region 61, and the liquid refrigerant 20 flows from the second region 62 toward the first region 61. As a result, even if the liquid level of the liquid refrigerant 20 tilts, a drop in the liquid level of the liquid refrigerant 20 in the first region 61 where the circuit board is stored can be prevented.

[0055] Next, a third embodiment will be described with reference to FIGS. 12 to 15. Configurations common to the first and second embodiments are given the same reference numerals, and detailed descriptions thereof will be omitted. FIG. 12 is an external perspective view of an electronic control device 1 according to a third embodiment of the present invention. FIG. 13 is a cross-sectional view taken along line XIII-XIII, cut at plane 71 shown in FIG. 12. FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. 13. FIG. 15 is a cross-sectional view taken along line XV-XV in FIGS. 13 and 14.

[0056] In this embodiment, four circuit boards 10 are stored inside the housing 2, and since the number of circuit boards 10 stored is increased, the thickness of the housing 2 in the front-to-back direction is increased compared to Example 2.

[0057] Four circuit boards 10 are mounted in a line in the front-to-rear direction inside the space formed by the housing 2 and the cover 3, and electronic components 11 are mounted on the circuit boards 10. The circuit boards 10 are connected to each other and to other electronic control devices via connectors and harnesses (not shown). A cooling water channel 33 is formed in the top of the housing, and cooling water inlets and outlets 32 are attached to both ends of the cooling water channel 33 for circulating cooling water 31 between the outside of the electronic control device and the circuit boards 10. A liquid refrigerant 20 is placed inside the housing 2.

[0058] The housing 2 is formed with wall portions 40 (40a, 40b, 40c, 40d) extending from the bottom surface (lower side) of the housing 2 toward the cooling water passage 33 above.

[0059] The interior of the housing 2, in which the liquid refrigerant 20 is placed, is divided into five regions by the wall 40 disposed inside the housing 2, as shown in Fig. 15. The interior is divided into a first region 61 in the center where the circuit board 10 is stored, and four second regions 62a, 62b, 62c, and 62d formed between the side wall of the housing 2 and the wall 40. The four corners of the housing 2 are sealed to prevent the liquid refrigerant 20 from entering. By sealing the corners, for example, it is possible to prevent the liquid refrigerant from flowing between the second region 62a and the second region 62d, and to prevent a decrease in the liquid refrigerant in the first region 61 when the liquid refrigerant level is tilted by the wall 40 and the valve 50, which will be described later.

[0060] Flow paths 51a, 51b, 51c, 51d are formed in the lower part of the wall portion 40 (40a, 40b, 40c, 40d) connecting the first region 61 and the second regions 62a, 62b, 62c, 62d, respectively, and valves 50a, 50b, 50c, 50d are installed in each of the flow paths 51a, 51b, 51c, 51d to allow the flow of liquid refrigerant 20 from the second region 62 toward the first region 61 and to restrict the flow from the first region 61 toward the second regions 62a, 62b, 62c, 62d.

[0061] Next, the flow of the liquid refrigerant 20 in this embodiment will be described in detail. First, using Figure 13, a case will be described where the liquid refrigerant 20 is tilted and the height of the liquid refrigerant 20 on the right side is higher. In this case, a flow similar to that shown in Figure 10 in the second embodiment occurs, and pressure is applied from the second region 62a to the first region 61 in the valve 50a, causing the valve 50a to open the flow path 51a, and the liquid refrigerant 20 flows from the second region 62a to the first region 61.

[0062] On the other hand, in valve 50b, pressure of the liquid refrigerant 20 is applied from the first region 61 to the second region 62b, so that valve 50b closes flow path 51b and no flow of the liquid refrigerant 20 occurs. The liquid levels of the liquid refrigerant 20 in second region 62c and second region 62d change in conjunction with the liquid level of the liquid refrigerant 20 in first region 61. When the condensed refrigerant condensed in cooling water channel 33 accumulates in second region 62c or second region 62d and becomes higher than the liquid level in first region 61, valve 50c or valve 50d opens to make the liquid level equal to that in first region 61. The action of these valves makes it possible to suppress a decrease in the liquid refrigerant 20 in first region 61 even when the liquid level of the liquid refrigerant 20 tilts.

[0063] 14, a case will be described in which the liquid refrigerant 20 tilts and the height of the liquid refrigerant 20 at the front side becomes higher. At this time, pressure is applied from the second region 62c to the first region 61 in the valve 50d, causing the valve 50d to open the flow path 51d, and the liquid refrigerant 20 flows from the second region 62d to the first region 61.

[0064] Meanwhile, in the valve 50c, pressure of the liquid refrigerant 20 is applied from the first region 61 toward the second region 62c, causing the valve 50c to close the flow path 51c and restricting the flow of the liquid refrigerant 20. The liquid level of the liquid refrigerant 20 in the second regions 62a and 62b changes in conjunction with the liquid level of the liquid refrigerant 20 in the first region 61. When the condensed refrigerant 22 condensed in the cooling water path 33 accumulates in the second region 62a or the second region 62b and becomes higher than the liquid level in the first region 61, the valve 50a or the valve 50b opens the flow path to make the liquid level equal to that in the first region 61. The action of these valves makes it possible to suppress a decrease in the liquid refrigerant 20 in the first region 61 even when the liquid level of the liquid refrigerant 20 tilts.

[0065] Next, a case will be described in which the liquid refrigerant 20 enters without blocking the four corners of the housing 2. Fig. 16 is a cross-sectional view of a comparative example 1 compared to the structure of Fig. 15 .

[0066] 16 , the four corners of the housing 2 are divided into regions 622 by wall portions 40 (40a, 40b, 40c, 40d). The wall portions 40 in contact with the region 622 are not provided with flow paths through which the liquid refrigerant 20 can flow. In this case, even if the condensed refrigerant condensed by the cooler 30 accumulates in the region 622 and the liquid level of the liquid refrigerant 20 in the region 622 rises, the liquid refrigerant 20 will not flow toward the first region 61 unless the liquid refrigerant 20 accumulates enough to overcome the wall portions 40. Therefore, the liquid refrigerant 20 in the first region 61 decreases by the amount of the liquid refrigerant 20 accumulated in the region 622, which may expose the electronic components 11 from the liquid refrigerant 20.

[0067] FIG. 17 is a cross-sectional view of Comparative Example 2 compared to the structure of FIG. 15 . In FIG. 17 , flow paths 511 through which liquid refrigerant 20 can flow are provided in wall 40 (40a, 40b, 40c, 40d) that contacts region 622 at each of the four corners of housing 2. Providing flow paths 511 in wall 40 prevents liquid refrigerant 20 from accumulating in region 622. However, if liquid refrigerant 20 tilts and flows from left to right, for example, flow 20a of liquid refrigerant 20 passes through valve 50a from second region 62a to first region 61, and flows 20d and 20e of liquid refrigerant 20 pass through flow paths 511 and flow toward second region 62b on the right. This reduces the amount of liquid refrigerant 20 in first region 61, potentially exposing electronic component 11 to the liquid refrigerant 20.

[0068] 18 is one example of a method for preventing the liquid refrigerant 20 from flowing through these flow paths 511. Figures 18 and 19 are cross-sectional views of modifications of the third embodiment.

[0069] As shown in Fig. 18 , in this modified example, a valve 50e that allows the liquid refrigerant to flow only in the direction of the arrow in the figure is installed in the flow path 511. By installing the valve 50e on the wall portion 40, even when the liquid refrigerant 20 is tilted and a flow from left to right occurs, as shown in Fig. 19 , the valve 50e can prevent the liquid refrigerant 20 from flowing toward the second region 62b on the right side. Although this method has the disadvantage of increasing the number of valves installed and making the structure more complex, it can suppress a decrease in the liquid refrigerant 20 in the first region 61 even when the liquid level of the liquid refrigerant is tilted.

[0070] Next, a fourth embodiment will be described with reference to Figures 20 and 21. The same components as those in the first to third embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted. Figure 20 is a front cross-sectional view of an electronic control device 1 according to the fourth embodiment of the present invention, as viewed from the normal direction of a circuit board 10.

[0071] In this embodiment, no valves are installed in the walls 40a, 40b that divide the first region 61 and the second region 62, and instead, flow paths 51a, 51b are provided that allow the liquid refrigerant 20 to flow between these regions. The opening areas of the flow paths 51a, 51b are adjusted according to the thickness of the wall 40. In this embodiment, the diameters of the openings of the flow paths 51a, 51b are smaller than the thickness of the wall 40a, 40b, which corresponds to the lengths of the flow paths 51a, 51b. According to this embodiment, the above-described configuration increases the flow loss that occurs when the liquid refrigerant 20 flows through the flow paths 51a, 51b, restricting the flow of the liquid refrigerant 20 between the first region 61 and the second region 62. This makes it possible to suppress a decrease in the liquid refrigerant 20 in the first region 61 even when the liquid level of the liquid refrigerant 20 is tilted. In FIG. 20, the flow paths 51a and 51b are depicted as a single opening in each of the wall portions 40a and 40b, but they may be a plurality of holes or may be lattice-shaped openings.

[0072] Fig. 21 is a cross-sectional view of a modified example of the fourth embodiment. In the modified example of Fig. 21, the flow paths 51a, 51b are formed in a cylindrical shape. The length of the cylindrical flow paths 51a, 51b is thicker (larger) than the thickness of the wall portions 40a, 40b. However, the inner diameter of the cylindrical flow paths 51a, 51b is smaller than the length of the cylindrical flow paths 51a, 51b. This allows for the same effects as those of the fourth embodiment to be obtained.

[0073] In this embodiment, a valve may be disposed in either one of the flow paths 51a and 51b.

[0074] Next, a fifth embodiment will be described with reference to Figures 22 and 23. The same components as those in the first to fourth embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted. Figure 22 is a front cross-sectional view of an electronic control device 1 according to a fifth embodiment of the present invention, as viewed from the normal direction of a circuit board 10.

[0075] In this embodiment, the flow paths 51a and 51b between the first region 61 and the second region 62 are configured as groove-like passages recessed in the bottom of the housing 2, rather than as openings provided in the wall surface of the wall portion 40. As in the fourth embodiment, by adjusting the opening area and length of the flow path 51 formed in the bottom of the housing 2 to change the flow loss of the liquid refrigerant 20, it is possible to suppress a decrease in the liquid refrigerant 20 in the first region 61 even when the liquid level of the liquid refrigerant 20 is tilted.

[0076] FIG. 23 is an enlarged view of the bottom of an electronic control device 1 according to a modified example of the fifth embodiment of the present invention. In FIG. 23, valves 50a and 50b are installed in the flow paths 51a and 51b, respectively, of the electronic control device shown in FIG. 22. The valves 50a and 50b are installed at the inlet and outlet portions of the flow paths 51a and 51b on the first region 61 side. The valves 50a and 50b allow the liquid refrigerant 20 to flow from the second region 62 toward the first region 61 and restrict the flow of the liquid refrigerant 20 from the first region 61 toward the second region 62. The valve 50a is shown in an open state when pressure of the liquid refrigerant 20 is applied from the second region 62 toward the first region 61, allowing a flow 20a of the liquid refrigerant 20 from the second region 62 toward the first region 61. Valve 50b also shows a state in which pressure of liquid refrigerant 20 is applied from first region 61 to second region 62. In this case, valve 50b closes flow path 51b, thereby restricting the flow 20b of liquid refrigerant 20 and preventing electronic component 11 from being exposed to liquid refrigerant 20.

[0077] Next, a sixth embodiment will be described with reference to Figures 24 to 29. Configurations common to the first to fifth embodiments are assigned the same reference numerals, and detailed descriptions thereof will be omitted. Figure 24 is a front cross-sectional view of an electronic control device 1 according to a sixth embodiment of the present invention, as viewed from the normal direction of the circuit board 10. In this embodiment, a third region 63 connected to the second region 62 is added to the electronic control device, and unlike the structures shown in the first to fifth embodiments, the interior of the electronic control device is not sealed but is open to the atmosphere.

[0078] 24 is located outside the second region 62, and is connected to the second region 62 (shown by the dashed line) at the bottom by a second flow path 512 through which liquid refrigerant can flow. An opening is provided at the top of the third region 63, and the third region 63 has an atmosphere opening 64 that connects to the atmosphere outside the electronic control device.

[0079] The second flow path 512 is positioned so as to be immersed in the liquid refrigerant 20. As a result, the boiling refrigerant filling the upper part of the second region 62 does not flow out into the atmosphere through the atmosphere opening 64 through the third region 63 because the liquid refrigerant 20 functions as a lid, preventing a decrease in the liquid refrigerant 20. The level of the liquid refrigerant 20 in the third region 63 is set to a height at which the pressure acting on the liquid refrigerant 20 in the second region 62 and the atmospheric pressure acting on the liquid refrigerant 20 in the third region 63 are balanced. An air filter or the like that allows air to flow may be attached to the atmosphere opening.

[0080] A first area 61 (shown by a dashed line) and a second area 62 are separated by walls 40a, 40b, and a circuit board 10 on which heat-generating electronic components 11 are mounted is disposed in the first area 61. The electronic components 11 are immersed in a liquid refrigerant 20, and the heat generated by the electronic components 11 causes the liquid refrigerant 20 to boil. The boiling refrigerant 21 is cooled and condensed by a cooler 30 disposed on the upper part of the housing 2, and returns to the liquid refrigerant 20 as condensed refrigerant 22. Cooling water 31 flows inside the cooler 30.

[0081] Valves 50a and 50b are installed at the bottom of wall portion 40 to allow liquid refrigerant 20 to flow from second region 62 to first region 61 and to restrict the flow of liquid refrigerant 20 from first region 61 to second region 62. Valves 50a and 50b open and close flow paths 51a and 51b, which serve as first passages. The action of these valves makes it possible to prevent a decrease in liquid refrigerant 20 in first region 61 even if the liquid level of liquid refrigerant 20 fluctuates, and to suppress exposure of electronic components 11 from liquid refrigerant 20.

[0082] Fig. 25 is a cross-sectional view of a first modified example of the sixth embodiment. In Fig. 25, the third region 63 is an electronic control device configured with a tubular connecting pipe 65. The connecting pipe 65 is provided in the second region 62. The lower part of the connecting pipe 65 is immersed in the liquid refrigerant 20, and the interior of the pipe is connected to the liquid refrigerant 20. The upper part of the connecting pipe 65 extends to the outside of the housing 2 and the cover 3, and the tip of the upper part is connected to the atmosphere through an atmospheric opening 64. The electronic control device of this embodiment can also be configured with such a tubular structure.

[0083] Fig. 26 is an external perspective view of the electronic control device 1 according to the second modification of the sixth embodiment. Fig. 27 is a cross-sectional view taken along the line XXVII-XXVII cut at the plane 71 shown in Fig. 26. The electronic control device 1 according to the second modification of the sixth embodiment is obtained by adding the structure of a third region 63 to the electronic control device shown in the third embodiment.

[0084] The third region 63 is connected to the second region 62 at its bottom by a second flow path 512 through which the liquid refrigerant 20 can flow. An opening is provided at the top of the third region 63, and the opening has an atmospheric opening 64 that connects to the atmosphere outside the electronic control device. The third region 63 is formed integrally with the housing 2. The third region 63 is formed so as to be thinner in the direction perpendicular to the paper surface of FIG. 27 , thereby reducing the amount of liquid refrigerant 20 that accumulates in the third region 63. A cooling water path 33 is formed in the housing 2, which cools the boiling refrigerant 21.

[0085] FIG. 28 is an external perspective view of an electronic control device 1 according to a third modification of the sixth embodiment. FIG. 29 is a cross-sectional view taken along the line XXIX-XXIX cut by the plane 71 shown in FIG. 28. In the electronic control device 1 according to the third modification of the sixth embodiment, the third region 63 is formed by a cylindrical connecting pipe 65. The lower end of the connecting pipe 65 is connected to the second region 62, and the third region 63 is formed by the space inside the connecting pipe 65. The upper end of the connecting pipe 65 is connected to the atmosphere via an atmospheric opening 64. In these figures, the connecting pipe 65 is arranged along the outer side surface of the housing 2, but the connecting pipe 65 may also be arranged to pass through the interior of the housing 2 as shown in FIG. 25.

[0086] Next, a seventh embodiment will be described with reference to FIGS. 30 and 31 . Components common to the first to sixth embodiments are assigned the same reference numerals, and detailed descriptions thereof will be omitted. FIG. 30 is a partially enlarged cross-sectional view of a wall portion 40 of an electronic control device 1 according to a seventh embodiment of the present invention. In the seventh embodiment, the valve 50 described in the first to sixth embodiments has a different structure. In FIG. 30 , the right side of the wall portion 40 is a first region 61, and the left side of the wall portion 40 is a second region 62. A flow path 51 that connects the first region 61 and the second region 62 is formed in the wall portion 40. The wall portion 40 is provided with a lid-shaped valve 52 that opens and closes the flow path 51.

[0087] 30(a) shows the state in which the valve 52 is open. When the pressure of the liquid refrigerant 20 in the second region 62 is higher than the pressure in the first region 61, the valve 52 moves to the right, creating a gap in the flow path 51. This gap allows the liquid refrigerant 20 to flow 20a from the second region 62 toward the first region 61.

[0088] 30(b) shows the state in which the valve is closed. When the pressure of the liquid refrigerant in the first region 61 is higher than the pressure in the second region 62, the valve 52 is pressed to the left, so no gap is created in the flow path 51 and the flow 20b of the liquid refrigerant 20 is obstructed.

[0089] Figure 31 is a cross-sectional view of a modified example of Example 7. In Figure 31, the valve is configured as a water wheel that can rotate in only one direction. In Figure 31, the right side of the wall portion 40 is a first region 61, and the left side of the wall portion 40 is a second region 62. In Figure 31, the water wheel 53 is structured so that it can rotate only counterclockwise, and a flow path 51 that connects the first region 61 and the second region 62 is formed below the water wheel 53.

[0090] 31(a) shows a state in which the water wheel 53 is rotating and the valve is open. When the pressure of the liquid refrigerant in the second region 62 is higher than the pressure in the first region 61, a force that rotates the water wheel 53 counterclockwise is applied, allowing the water wheel 53 to rotate. As a result, a flow 20a of the liquid refrigerant from the second region 62 to the first region 61 is possible.

[0091] 31(b) shows a state in which the water turbine 53 is stopped and the valve is closed. When the pressure of the liquid refrigerant in the first region 61 is higher than the pressure in the second region 62, a force is applied to the water turbine 53 to rotate it clockwise, but the water turbine does not rotate because it is designed to rotate only counterclockwise. As a result, the flow 20b of the liquid refrigerant 20 from the first region 61 to the second region 62 is restricted.

[0092] The present disclosure is not limited to the above-described embodiments and modifications. For example, it is possible to replace part of the configuration of the above-described embodiments and modifications with other configurations, or to combine the configurations of the above-described embodiments and modifications. It is also possible to add, delete, or replace part of the configuration of the above-described embodiments and modifications with other configurations. In the present disclosure, the wall portion 40 is arranged to have at least two of the four sides surrounding the circuit board 10, but the wall portion 40 may be configured with only one side.

[0093] DESCRIPTION OF SYMBOLS 1...Electronic control device, 2...Housing, 3...Cover, 10...Circuit board, 11...Electronic component, 20...Liquid refrigerant, 21...Boiling refrigerant, 22...Condensed refrigerant, 23...Exposed portion, 30...Cooler, 31...Cooling water, 33...Cooling water channel, 40, 40a, 40b, 40c, 40d...Wall portion, 41a, 41b...Inclined portion, 50, 50a, 50b, 50c, 50d, 50e...Valve, 51, 51a, 51b, 51c, 51d...Flow path, 61...First region, 62...Second region, 63...Third region, 65...Connecting pipe

Claims

1. An electronic control device mounted on a moving body, comprising: a circuit board on which electronic components are mounted; a housing that houses the circuit board and a liquid refrigerant; a cooler arranged in an upper part of the housing; and a wall extending from the bottom of the housing toward the cooler and dividing the inside of the housing into a first area and a second area, wherein the circuit board is immersed in the liquid refrigerant in the first area, and at least two flow paths are formed in the housing that connect the first area and the second area, and the flow paths are equipped with valves that allow the liquid refrigerant to flow from the second area toward the first area and limit the flow of the liquid refrigerant from the first area toward the second area.

2. An electronic control device according to claim 1, wherein the flow path and the valve are provided in the wall portion.

3. An electronic control device according to claim 1, wherein the flow path and the valve are provided at the bottom of the housing.

4. An electronic control device according to claim 1, characterized in that the valve is constituted by a water wheel that is rotated only by the liquid refrigerant flowing from the first region to the second region.

5. An electronic control device according to claim 1, wherein the wall portions are provided with inclined portions that are inclined so that the opposing wall portions approach each other as they approach the cooler.

6. An electronic control device according to claim 5, wherein the lower surface of the cooler is inclined downward from the center of the cooler toward the outer periphery.

7. An electronic control device according to claim 6, wherein the cooler is formed integrally with the housing.

8. An electronic control device according to claim 1, comprising a third area located outside the second area and communicating with the second area, the top of the third area being open.

9. An electronic control device according to claim 1, wherein the second region is provided with a connecting pipe whose lower part is immersed in the liquid refrigerant and whose upper part is open to the atmosphere.

10. An electronic control device mounted on a moving body, comprising: a circuit board on which electronic components are mounted; a housing that houses the circuit board and a liquid refrigerant; a cooler arranged on the upper surface of the housing; and a wall extending from the bottom of the housing toward the cooler and dividing the housing into a first area and a second area, wherein the circuit board is immersed in the liquid refrigerant within the first area, and at least two flow paths are formed within the housing that connect the first area and the second area, and the diameter of the opening of each flow path is smaller than the length of the flow path to restrict the flow of the liquid refrigerant from the first area to the second area.

Images