Patent Application
20220316821
The present invention relates to a cooling apparatus, particularly to a cooling apparatus that efficiently cools heat-producing devices (e.g., an optical element for high-power laser and the substrate of a circuit that requires a large amount of power).
Optical elements, electric circuits, and electronic components that consume a large amount of power, such as CPUs, and computers including these components are installed such that they operate in an appropriate temperature range, by means of air cooling using a fan or the temperature control of the entire space in which they are installed.
However, air cooling with a fan and temperature control by air conditioning also consume a large amount of power and are not considered efficient. Cooling with an electronic component such as a Peltier element not only consumes a large amount of power, but may also cause the cooling target or the Peltier element to fail depending on the difference between the cooling target and the Peltier element in the coefficient of thermal expansion.
In view of the above, some computers use water cooling. However, the cooling apparatus is significantly small, and its technology is not versatile.
In recent years, high-power lasers of several kilowatts have been increasingly used to process metal parts of automobiles, aircraft, and turbines for power plants, for example. The optical elements forming an optical system of high-power laser absorb a part of the energy of the laser and produce heat (NPL 1). At this time, the energy applied to the optical elements is about several hundred watts, and sufficient cooling cannot be achieved with conventional air cooling or air conditioning.
As described above, in recent years, heat-producing devices have been increasingly used, such as optical elements for high-power laser for processing metal parts and the substrates of circuits that require a large amount of power. Since conventional air cooling and air conditioning cannot achieve sufficient cooling, an apparatus has been sought that achieves efficient cooling.
To solve this problem, it is an objective of the present invention to provide a cooling apparatus that efficiently cools a heat-producing device.
To achieve such an objective, an example of an embodiment of the present invention has the following configurations.
For example, a cooling apparatus that holds a heat-producing device as a cooling target and is provided in a flow passage of a liquid cooling medium for cooling is configured such that the liquid cooling medium passes at high speed while in contact with a cooling surface of the cooling target. Alternatively, a structure or a screw is placed in the cooling apparatus to increase the flow velocity of the cooling medium.
A cooling apparatus for cooling a cooling target with a liquid cooling medium, the cooling apparatus including:
The cooling apparatus according to configuration 1, wherein in a section of the cooling medium holding portion where the cooling medium comes into contact with the cooling target in the flow passage, a flow passage cross-sectional area of an inlet of the section where the cooling medium flows in is greater than a flow passage cross-sectional area of an outlet of the section where the cooling medium flows out.
The cooling apparatus according to configuration 2, wherein a cross section of the inlet of the cooling medium taken perpendicular to the flow passage is parallel to a cross section of the outlet of the cooling medium taken perpendicular to the flow passage.
The cooling apparatus according to configuration 3, wherein the center of the cross section of the inlet of the cooling medium and the center of the cross section of the outlet of the cooling medium are on the same straight line parallel to the base of the cooling medium holding portion.
The cooling apparatus according to configuration 2 or 3, wherein a cross-sectional area of a flow passage to the inlet of the cooling medium taken perpendicular to a traveling direction of the cooling medium is equal to a cross-sectional area of the inlet of the cooling medium taken in the same manner, and a cross-sectional area of the outlet of the cooling medium taken in the same manner and a cross-sectional area of a flow passage from the outlet taken in the same manner are both equal to the cross-sectional area of the inlet of the cooling medium.
The cooling apparatus according to configuration 5, wherein the cross-sectional shape of the inlet is identical to the cross-sectional shape of the outlet.
A cooling apparatus for cooling a cooling target with a liquid cooling medium, the cooling apparatus including:
The cooling apparatus according to configuration 7, wherein the structure is a plate-shaped member substantially having a half-moon cross-sectional shape and is placed along the flow passage of the cooling medium at a position where the structure bifurcates the flow passage, a surface of the structure that faces the cooling surface is a convex surface, and a surface of the structure that faces a base is a flat surface parallel to a traveling direction of the cooling medium.
The cooling apparatus according to configuration 8, wherein a length of a streamline from a bifurcation to a confluence of the cooling medium flowing along a surface of the structure is longer on the convex surface side than on the flat surface side.
A cooling apparatus for cooling a cooling target with a liquid cooling medium, the cooling apparatus including:
The cooling apparatus according to configuration 10, wherein the screw is placed in the vicinity of the center of a base of the cooling medium holding portion, and the screw has a rotation axis that is perpendicular to a cooling surface of the cooling target, and the screw rotates in a direction that causes the cooling medium to flow to the cooling surface.
The cooling apparatus according to configuration 10, wherein the screw is placed in the vicinity of an inlet or an outlet of the cooling medium in a wall surface of the cooling medium holding portion, the screw has a rotation axis that is parallel to the cooling surface of the cooling target, and the screw rotates in a direction that causes the cooling medium to flow from the inlet to the outlet.
According to the cooling apparatus of the present invention described above, a cooling apparatus that efficiently cools a heat-producing device can be provided.
Embodiments of the present invention are described in detail below with reference to the drawings.
As described above, the optical component for an optical system that uses a laser of several kilowatts absorbs a part of the energy of the laser and produces heat. At this time, the energy absorbed by the optical component is about several hundred watts, and air cooling and air conditioning cannot achieve sufficient cooling and may cause distortion of the optical system or damage to the optical component.
For this reason, a cooling apparatus is provided on the optical component as shown in
In
As shown in the figure, the radiator 220 can be forcibly air-cooled with the fan 230, for example, but it can also be naturally air-cooled without a fan. Alternatively, when a source of a low-temperature cooling medium such as cold water can be provided, a so-called non-circulating open system may be used in which the cooling medium is driven only by the pump without involving a radiator and the cooling medium is not circulated.
The cross-sectional view of the cooling apparatus 201 of
As shown in
In the first embodiment of
Furthermore, the directions of the flow passages through which the cooling medium 401 enters and exits at the inlet 204 and the outlet 205 do not necessarily have to be perpendicular to the sides of the container 203. One or both of the directions of the flow passages at least at the inlet and the outlet may be diagonal to the side including the inlet or the outlet.
Additionally, the flow passage of the inlet 204 and the flow passage of the outlet 205 may be the same or different in cross-sectional area. The opening of the inlet 204 and the opening of the outlet 205 may be the same or different in cross-sectional shape. When the inlet 204 and the outlet 205 are provided in sides of the container 203, the centers of the cross sections of the openings of the inlet 204 and the outlet 205 may or may not be located on the same straight line parallel to the cooling surface 102 of the cooling apparatus 201 or the base of the container 203.
The number of the inlet 204 and the number of the outlet 205 do not have to be one, and there may be a plurality of pairs of inlets and outlets. Also, the inlet and outlet do not have to be provided in pairs. In one configuration example, an inlet 204 or outlet 205 may be provided in one of four diagonal corners of the shape of a rectangular solid of the container 203, one of the four sides of the base, or one of the four sides perpendicular to the base such that the flow passage is directed toward the center of the container 203 and at least one pair of inlet and outlet face each other. The shape of the container 203 is not limited to a rectangular solid.
In the cooling apparatus of the present embodiment, the section corresponding to the cooling surface where the cooling medium comes into contact with the cooling target in the flow passage in the container holding the cooling medium, the section where the cooling medium flows in, and the section where the cooling medium flows out have different flow passage structures so that the cooling medium passes at high speed while in contact with the cooling surface of the cooling target to achieve high cooling efficiency.
To improve the cooling efficiency, it is desirable that the cooling medium 401 move at high speed while in contact with the cooling surface 102. To this end, it is preferable that the cross-sectional area of the outlet 205 be larger than the cross-sectional area of the inlet 204, the directions of the flow passages of the inlet 204 and the outlet 205 be perpendicular to the sides including the inlet 204 and the outlet 205, the centers of the cross sections of the inlet 204 and the outlet 205 be on the same straight line parallel to the cooling surface 102 or the base of the container 203, and at least one pair of an inlet and an outlet face each other.
In such a cooling apparatus 201, the driving pressure Pout required to press the cooling medium 401 out of the outlet 205 from the inlet 204 can be calculated by the following Expression (1).
As indicated by this Expression (1), the larger the cross-sectional area of the flow passage of the outlet 205, in other words, the cross-sectional area of the flow passage perpendicular to the traveling direction (streamline) of the flow of the cooling medium 401, the smaller the Pout. The cooling medium 401 can flow at a higher speed while in contact with the cooling surface 102 in proportion to the flow rate of the cooling medium 401 flowing into the inlet 204.
In the optical system of
Since the plane mirror cannot be sufficiently cooled through cooling with gas or temperature control by air conditioning, a cooling method was employed that uses water as the cooling medium. The cooling mechanism employed had an inlet, for the incoming cooling medium, and an outlet that were identical in cross-sectional area. The water pressure (pressure) calculated using Expression (1) caused the plane mirror to have a radius of curvature and to become a convex mirror.
Then, the configuration of the cooling apparatus of the first embodiment of
The cooling medium 401 flowing in from the inlet 204 collides with the structure 501 and then immediately bifurcates into flows above and below the structure 501. The length of the streamline from the bifurcation to the confluence of the cooling medium 401 flowing separately on the upper and lower surfaces of the structure 501 is longer on the convex surface side than on the flat surface side.
According to NPL 2 (see pages 7 to 105), these two bifurcated flows of the cooling medium 401 merge at the end of the structure 501 at the same time. That is, the flow velocity of the flow of the cooling medium 401 above the structure 501 is greater than the flow velocity of the cooling medium 401 below the structure 501.
As a result, the flow velocity of the cooling medium flowing above the structure 501 is greater than the flow velocity calculated from the flow rate of the incoming cooling medium 401. This increases the volume of the cooling medium 401 flowing in contact with the cooling surface 102 per unit time, thereby improving the cooling efficiency as compared with a state without the structure 501.
When the cooling target is an electric circuit board, the board becomes a heat source of several hundred watts. Sufficient cooling cannot be achieved by air cooling or air conditioning, and the operation as designed cannot be achieved.
Thus, a cooling apparatus having the configuration of the second embodiment of
As a result, as compared with a configuration without the structure 501, the flow velocity on the cooling surface was doubled, and the cooling efficiency was also doubled. Consequently, as compared with a cooling method using air cooling, air conditioning, or Peltier elements, the power consumption was reduced by 50%, and sufficient cooling was achieved.
The flow (convection) of the cooling medium created when the screw 502 rotates in the configuration of
As shown in
The cooling medium that has absorbed heat from the cooling target 101 on the cooling surface 102 has a higher temperature than the cooling medium entering through the inlet 204. As such, when the screw 502 is rotated in a direction that causes the cooling medium to flow to the cooling surface 102, the cooling medium that is entering through the inlet 204, which is near the base of the container 203, and has a relatively low temperature rises. Accordingly, the cooling medium 402 absorbs heat from the cooling surface 102, descends along the inner wall of the cooling apparatus 201, is raised again by the screw 502, and finally flows out through the outlet 205, thereby creating the convection.
As a result, the incoming cooling medium 401 of low temperature is continuously supplied to the cooling surface 102. Also, the cooling medium 402 of a relatively high temperature that is created by the convection flows out through the outlet 205, which is provided in the vicinity of the cooling surface 102, with its buoyancy. Although the outlet 205 is provided in one position in
The configuration of the cooling apparatus of the third embodiment of
Rotating the screw 502 to direct the cooling medium 401 to the outlet 205 increases the flow velocity, thereby improving the cooling efficiency. In this configuration, it is preferable that the centers of the cross sections of the outlet 205 and the inlet 204 be on one straight line parallel to the base of the cooling apparatus 201, and that the flow passages of the inlet 204 and the outlet 205 be perpendicular to the inner walls.
The screw may be placed on the side including the outlet 205 of the cooling medium, instead of the side including the inlet 204. Furthermore, one or more screws may be placed on either or both of the sides including the inlet 204 and the outlet 205. When a plurality of inlets and outlets is provided, a plurality of screws may be provided according to the openings of the inlets and outlets. The blades of the screw preferably have a diameter corresponding to the diameter of the inlet or outlet opening.
As shown in
The configuration of
In the comparison example of
In contrast, in the fifth embodiment of the present invention shown in
In the fifth embodiment of the present invention of
The configuration of
The cooling target of the sixth embodiment is an optical element that is a heat source of several hundred watts. As such, sufficient cooling cannot be achieved with conventional air cooling, air conditioning, a Peltier element, or the like.
As such, cooling was performed with a cooling apparatus having the configuration of the sixth embodiment. As a result, as compared with a configuration without the structure and the screw, the flow velocity on the cooling surface was doubled, and the cooling efficiency was also doubled. Sufficient cooling was thus achieved.
Consequently, as compared with a conventional cooling method using air cooling, air conditioning, or Peltier elements, the power consumption was reduced by 50%, and sufficient cooling was achieved.
As described above, the cooling apparatus of the present invention can efficiently cool a heat-producing device.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/030361 | 8/1/2019 | WO |
