JPS6410400B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the improvement of a thermal louver mounted on a spacecraft such as an artificial satellite to control the heat of onboard equipment. The present invention provides a thermal louver that uses a shape memory element to control the rotation of the blades during sunlight.

First, a conventional thermal louver will be briefly explained using diagrams. Figure 1 is a configuration diagram of a conventional device of this type, Figure 2 is a diagram of operating characteristics of a conventional device of this type,
FIG. 3 is a diagram showing the operating state of a conventional device of this type. In the figure, 1 is a board to which heating elements such as on-board equipment are attached and is subject to heat control, 2 is heat radiated from this board 1, and 3 is a rotation in the left and right directions on the paper to control the radiation of heat 2. This blade has been surface-treated to have a high heat reflectance and a low heat absorption. 4 is a rotating shaft that supports the rotation of the blade 3; 5 is a bimetal spring that is attached to the end of the rotating shaft 4 and serves as a drive mechanism that provides rotational force to rotate the blade 3 in relation to the temperature of the plate 1; 6 is a housing in which the blade 3 houses the bimetal spring 5 and the like, is attached to the substrate 1, and has an opening on the radiation side of the heat 2; This is a sunlight shielding material (such as silver-deposited Teflon film) that reflects the sun's rays.

In such a configuration, when the temperature of the substrate 1 increases, heat 2 is radiated from the substrate 1. Since this heat 2 is reflected when it hits the blade 3, the amount of heat radiation from the substrate 1 is determined depending on the rotation angle θ of the blade 3. In other words, in a thermal sense, the substrate 1 has a maximum heat radiation surface when θ is 90 degrees, and has a minimum heat radiation surface with no heat radiation when θ is 0 degrees.

Now, the blade 3 rotates around the rotating shaft 4 within a range of θ from 0 degrees to 90 degrees, and the force for this rotation is provided by the bimetal spring 5. That is, the bimetal spring 5 is the substrate 1
Since it is in a thermally conductive state, when it is warmed, it rotates in the direction in which θ becomes larger, that is, in the counterclockwise rotation direction as seen in the paper, and when it is cooled, it rotates in the clockwise rotation direction.

Looking at this operation in Figure 2, Figure 2 shows the state of θ at the temperatures T ₀ , T ₁ , T ₂ (T ₀ <T ₁ <T ₂ ) of the substrate 1. When maintaining the temperature at T ₀ , when the temperature rises and moves from T to T ₁ and then to T ₂ , θ increases along the curve C ₁ ,
Then, as the temperature decreases from T ₂ to T ₁ to T ₀ , θ decreases along curve C ₂ .

Next, when the blade 3 rotates, sunlight 8 is transmitted to the substrate 1.
The sunlight 8 is reflected by the sunlight shielding material 7 attached to the housing 6 in order to prevent it from entering the body, and the heat 2
Only the sunlight is allowed to pass through the sunlight shielding material.
Since thermal negative feedback is performed in this way, it is possible to control the temperature of the substrate 1, and it is currently widely used in artificial satellites and the like.

However, in such a conventional thermal louver, since the rotation angle θ of the blade 3 is determined only by the temperature of the substrate 1, as shown in FIG. 3, the temperature of the substrate 1 is T ₀ in the shade. As the temperature increases from T ₁ to T ₂ , θ changes from 0° to 90°, that is, from fully closed to fully open, so appropriate thermal control is performed, but the same operation occurs even in sunlight. , especially when it falls within the range of the incident angle θ of sunlight 8, it becomes impossible to radiate heat, and in some cases, the temperature increases, not only making thermal control impossible but also thermally damaging the equipment. There is a risk of thermal runaway.

Therefore, sunlight shielding material 7 is used to thermally shield sunlight 8, but it has a negative effect on the heat radiation of heat 2, and as a result, the efficiency of heat radiation deteriorates significantly. There was a problem that the surface had to be made larger, which increased the weight and shape.

This is a big problem in artificial satellites where the shape and dimensions are restricted, as there are restrictions on the mounting position and size of the thermal louver.
A solution was desired.

This invention improves the problems with conventional thermal louvers and provides a thermal louver with a simple structure that prevents thermal runaway when sunlight is incident on the thermal louver. do.

FIG. 4 is a front view showing the structure of an embodiment of the present invention, FIG. 5 is a side view showing the structure of an embodiment of the invention, and FIG. 6 is a diagram showing stress versus deformation characteristics of a shape memory element. , FIG. 7 is a diagram showing the deformation amount versus temperature characteristic of the shape memory element, FIG. 8 is a diagram showing the pseudoelasticity characteristic of the shape memory element, and FIG. 9 is an operation state table of an embodiment of the present invention.

In the figure, 1, 2, 3, 4, and 8 are the same as in FIG. 9 is a first shape memory element formed of a shape memory alloy wire in the shape of a series-wound spring, one end of which is attached to the substrate 1 while maintaining thermal conductivity, and the other end is attached to the mover 13; is a second shape memory element having the same material and shape as the first shape memory element 9, one end of which is attached to the heat absorption plate 11 while maintaining thermal conductivity, and the other terminal is attached to the mover 13. be. The heat-absorbing plate 11 is made of a heat-conducting material whose surface is treated to increase its infrared absorption rate, and is attached to the back surface of the infrared window 12. An infrared window 12 is attached to the surface of the heat absorption plate 11 and is made of an infrared transmitting material (for example, crystalline magnesium bromide) formed into a flat plate to refract the infrared rays contained in the sunlight 8 and make them enter the heat absorption plate 11. ,
Reference numeral 13 is made of a heat insulating material and is formed into a long cube shape, and has a hole 15 passing through the inside to connect the first shape memory element 9 and the second shape memory element 9.
The mover 14 installed between the shape memory element 10 of the mover 14 has one end inserted into the hole 15 of the mover 13 and the other end connected to the rotating shaft 4 in order to convert the vertical movement of the mover 13 into rotational movement. 16 is a support base for fixing a bearing 17 that supports the rotating shaft 4; 18 is a support that fixedly connects the heat absorption plate 11 and the substrate 1; and 19 is a heat incidence surface of the infrared window 12.

Next, the operation of the present invention will be explained using FIGS. 4 to 9. In FIGS. 4 and 5, the substrate 1
The function of the blades 3 to control the amount of heat 2 radiated from the blades is the same as that shown in FIG. Now, when a heating element such as an electronic device is attached to the substrate 1 and an attempt is made to control the temperature of the electronic device to a predetermined temperature by controlling the temperature of the substrate 1, the radiation of heat 2 related to the substrate 1 and the solar radiation As a drive mechanism for rotating the blade 3 to control the incidence of the light 8, a first shape memory element 9;
The second shape memory element 10, the heat absorption plate 11, the infrared window 12, the mover 13, and the converter 1
4 to generate a rotational force for rotating the blades 3, their functions will be explained first.

In the parent phase, the first shape memory element 9 returns to its original shape, extends in the longitudinal direction, and assumes an elongated shape that rotates the blade 3 clockwise in the plane of the drawing from a rotation angle θ of 0 degrees to −90 degrees. Also, in the martensitic phase, the blade 3
is compressed in the longitudinal direction so that θ is rotated counterclockwise in the paper from 0 degrees to +90 degrees.

In addition, the second shape memory element 10 rotates the blade 3 counterclockwise in the plane of the paper at a rotation angle θ from 0 degrees to +90 degrees.
It becomes an elongated shape in which the blade 3 is rotated from 0 degrees to -90 degrees in the martensitic phase, and a compressed shape in which the blade 3 is rotated from 0 degrees to -90 degrees in the martensitic phase. Since the heat absorbing plate 11 is fixed by the struts 18, the differential stress caused by the expansion and compression movements of the first shape memory element 9 and the second shape memory element 10 is applied to the movable element 13. 1 and the heat absorbing plate 11, the transducer 14 inserted into the hole 15 provided in the movable element 13 is moved up and down, converting the above-mentioned stress, and the rotating shaft 4
gives rotational force to. Since this rotating shaft 4 is supported by a bearing 17 held on a support stand 16, it can rotate smoothly. Next, the first shape memory element 9 is attached to the substrate 1 and has good thermal conductivity, so that it has the same temperature as the substrate 1. on the other hand,
The second shape memory element 10 has an infrared window 12
Since the second shape memory element 10 is attached to a heat absorption plate 11 that absorbs the infrared rays of the sunlight 8 collected by the infrared rays window 12 while maintaining thermal conductivity, the temperature of the second shape memory element 10 is the same as that of the sunlight 8 that enters the infrared window 12. The angle of incidence θ _i
It is determined by the amount of heat input that depends on .

The amount of heat incident is detected if the incident angle θ _i of the sunlight 8 incident on the heat incidence surface 19 of the infrared window 12 is within the range of the unique Brillustre angle θ _b of the infrared window 12 . It passes through, but
If it is outside the range of θ _b , it will be totally reflected, so for sunlight 8 that enters the light incidence surface 19 at a specific angle of incidence θ _i ,
The amount of heat incident thereon can be detected.

Now, what kind of overall operation is performed by combining the operations of each component shown in FIGS. 4 and 5 will be explained. First, the relationship between the amount of deformation and stress of the first shape memory element 9 and the second shape memory element 10 is shown by curve C ₃ and curve C ₄ in FIG.
For example, the first shape memory element 9 is in the matrix phase and has the characteristics of _C4 , while the second shape memory element 10 is in the martensitic phase and has the characteristics of _C3. When the force F corresponds to the difference between C ₄ and C ₃ is generated, the reverse transformation stress of the first shape memory element 9 and the second shape memory element 10 can be differentially extracted.

Next, the relationship between temperature and deformation is shown in Figure 7.
Since the temperature vs. deformation characteristics of the first shape memory element 9 and the second shape memory element 10, which are shaped like _C5 and _C6 , are made to match, the transformation end temperature Mf
Below, both become martensitic phases, and as the temperature increases sequentially, it changes along the curve C ₅ , the reverse transformation to the parent phase starts at the reverse transformation start temperature As, and the reverse transformation ends at the reverse transformation end temperature Af, The amount of deformation is constant. Next, when the temperature decreases, it changes along the curve _C6 , and when it reaches the transformation start temperature Ms to the martensitic phase, the transformation starts and ends at Mf.

First shape memory element 9 having such characteristics
How the blade 3 operates when the temperature of the substrate 1 and the second shape memory element 10 are set to the temperature of the substrate 1 and the heat absorption plate 11 will be explained with reference to FIGS. 7 and 9. In FIG. 7, the first shape memory element 9 and the second
The temperatures of the shape memory element 10 are exemplarily shown as T ₁ , T ₂ , T ₃ , T ₄ and T ₅ . The rotation angle θ of the blade 3 at these temperatures is shown in FIG.
In FIG. 9, T ₁ , T ₂ , T ₃ , T ₄ and T ₅ in the row direction indicate the temperature of the second shape memory element 10, and in the column direction
T ₁ , T ₂ , T ₃ , T ₄ and T ₅ are the first shape memory element 9
indicates the temperature of The rotation angle θ at these temperatures
For example, when there is no sunlight 8 incident, that is, in the shade, there is no heat input to the infrared window 12 and the heat absorption plate 11, and the heat absorption plate 11 absorbs no heat. Since only radiation is performed, the temperature decreases to T ₁ (eg -10°C). At this time, the second shape memory element 10 enters a martensitic phase at a temperature below Mf, so that it is deformed by a slight force. And the temperature of substrate 1 is T ₁
When the _temperature is gradually increased from
Transform like C ₅ . Therefore, as shown in the first row of FIG. 9, the blade 3 is fully closed at T ₁ ,
Fully open at _T5 . This operation is the same as in FIG. Next, when the heat absorbing plate 11 becomes high in temperature during sunshine and reaches T ₅ , the second shape memory element 10 is in the matrix phase as shown in the fifth column of FIG. When the shape memory element 9 is at _T1 , it enters the martensitic phase and the blade 3 rotates counterclockwise by 90 degrees.
The substrate 1 is heated by the sunlight 8 and its temperature rises. Next, when the temperature of the first shape memory element 9 reaches T ₂ (for example, 30° C.), its length is slightly expanded and the blade 3 is set at a rotation angle of 80° counterclockwise. At this time, sunlight 8 is incident on the light incident surface 19 of the infrared window 12 at an incident angle θ _i within θ _b in FIG. 4, and most of it is blocked and reflected by the blade 3 and does not reach the substrate 1. The light is incident on the substrate 1 by mutual reflection between the blades 3. On the other hand, the substrate 1 has blades 3
Since it is open, heat is radiated, and the temperature of the substrate 1 is determined by the ratio of both intensities. By the way, as the rotation angle θ of the blade 3 becomes smaller, the proportion of sunlight 8 that is reflected becomes larger, and therefore the amount of sunlight 8 that is incident on the substrate 1 becomes smaller. Therefore, when the substrate 1 is at a low temperature, the blades 3 are rotated counterclockwise to increase the proportion of sunlight 8 that enters the substrate 1 to warm it up.
When the substrate 1 is at a high temperature, the blades 3 are closed to prevent light from entering the substrate 1.

The relationship between the incident amount of sunlight 8 and the temperature of the substrate 1 is determined by the Brillister angle θ _b of the infrared window 12, the heat absorption rate of the heat absorption plate 11, and the heat of the first shape memory element 9 and the second shape memory element 10. The desired state can be set by adjusting the elastic properties.

Next, when the first shape memory element 9 and the second shape memory element 10 are both in the parent phase, that is, when both are in an elongated state, they are deformed by mutual force. The pseudoelastic effect shown in FIG. 8 occurs.

In other words, when stress is applied to the matrix, curve C ₇
It has excellent elasticity in that it deforms along the curve _C8 but returns to its original shape along the curve C8 when the stress is removed. When the temperature of ₅ is reached, the blades 3 are expanded together, and the action of closing the blades 3 by balancing their respective stresses can be repeated accurately.

As explained above, according to the present invention, when sunlight enters the thermal louver, the rotation angle θ of the blade 3 is adjusted according to the temperature of the heat absorption plate 11 and the substrate 1, so that thermal runaway during sunlight can be prevented. This has the advantages of high prevention and safety and high heat exhaust effect.

Furthermore, since sunlight can be appropriately allowed to enter the substrate 1 when the substrate 1 is at a low temperature, the present invention can also absorb heat, compared to conventional thermal louvers that only exhaust heat. This provides the advantage of being able to provide thermal control over both high and low temperatures.

In the above embodiment, the heat absorption plate 11 was provided on the back surface of the infrared window 12, but the infrared window 12 may be omitted and provided on the back surface of the light incident surface 19. It may be made to have a convex or convex surface, or a combination of these may be used to provide the required heat absorption characteristics. Also, the pillar 18 is connected to the housing 6
There are various modifications possible without departing from the gist of the present invention, such as the shape memory element may be integrated with the shape memory element, or the shape memory element may be plate-shaped or rod-shaped.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional thermal louver, Figure 2
FIG. 3 is a diagram showing the operational characteristics of a conventional thermal louver, FIG. 4 is a front view showing the configuration of an embodiment of the present invention, and FIG.
FIG. 5 is a side view showing the configuration of an embodiment of the present invention, FIG. 6 is a diagram showing stress versus deformation characteristics of the shape memory element, and FIG. 7 is a diagram showing deformation vs. temperature characteristics of the shape memory element. , FIG. 8 is a diagram showing the pseudoelastic characteristics of the shape memory element, and FIG. 9 is a diagram showing the operating state of one embodiment of the present invention. In the figure, 1 is the board, 2 is the heat, 3 is the blade, 4 is the rotating shaft, 5 is the bimetal spring,
6 is a housing, 7 is a sunlight shielding material, 8 is sunlight, 9 is a first shape memory element, 10 is a second shape memory element, 11 is a heat absorption plate, 12 is an infrared window,
13 is a mover, 14 is a converter, 15 is a hole, 16 is a support base, 18 is a column, and 19 is a heat incidence surface. It should be noted that the same or corresponding parts in the drawings are designated by the same reference numerals.

Claims (1)

[Claims] 1 comprising blades arranged in parallel on one side of a substrate on which a heating element of an electronic device or the like is attached, and a drive mechanism attached to one side of the substrate to rotate the blades, the blades being rotated by the drive mechanism. A thermal louver that adjusts the amount of heat dissipated from the board and controls the heat of the board includes a heat absorbing plate provided on the back side of the heat incidence surface to the thermal louver, and one end of which is attached to the board, a first shape memory element that assumes an expanded shape and a compressed shape depending on the shape; a second shape memory element that has one end attached to the heat absorption plate and operates in the same manner as the first shape memory element; attached between the other end of the first shape memory element and the other end of the second shape memory element;
a mover that reciprocates between the substrate and the heat absorbing plate due to differential stress caused by the expansion and compression motion of the shape memory element; one end is connected to the rotation axis of the blade, and the other end is connected to the mover The thermal louver is characterized in that the drive mechanism is constituted by a converter that is attached to the movable element and converts the reciprocating motion of the movable element into rotational motion and applies the rotational force to the rotation axis of the blade.