CN101424862A - Thermal switch for heat control system of camera - Google Patents

Abstract

The invention relates to a thermal control system switch applied to temperature sensitive devices, in particular to a thermal switch used in a thermal control system of a space camera, which consists of left and right heat conduction blocks and a movable heat conduction switch that can move left and right between the left and right heat conduction blocks. block, a telescopic rod made of a material with a thermal expansion coefficient greater than that of the left and right heat conduction blocks and the movable heat conduction block, and a spring; the left and right heat conduction blocks are provided with blind holes opening to the movable heat conduction block, The sliding fit is arranged in the blind hole of the left heat conduction block, and the spring is arranged in the blind hole of the right heat conduction block. Through the thermal expansion and cold contraction of the telescopic rod, the movable heat conduction block is respectively in contact with the left and right heat conduction blocks alternately to change the heat conduction channel. The utility model has the advantages of simple structure, high reliability and long service life, and realizes the automatic temperature control function of temperature sensitive devices.

Description

Thermal switch for space camera thermal control system

technical field

The invention relates to a thermal control system switch applied to temperature sensitive devices, in particular to a thermal control component that can be used as a variable heat dissipation channel for space optical remote sensor CCD focal plane components and the like.

Background technique

At present, most space cameras use CCD as the detection device. However, it is sensitive to temperature. Excessively high temperature levels and excessive temperature fluctuations will increase the dark current and thermal noise of the CCD device, resulting in a decrease in signal-to-noise ratio and affecting image quality. Therefore, it is the goal of CFPA thermal design to ensure that the CCD focal plane assembly (CFPA) is at a lower temperature level and within a smaller temperature fluctuation range.

Due to the space environment where the camera is located, as well as the requirements of optical and mechanical structures, CFPA is installed in a relatively narrow and airtight environment. In order to reduce the interaction between the various parts of the camera, the heat generated by the CCD during operation should be discharged to the external space through the cooling channel. As a reasonable heat dissipation path, CFPA acts as a heat source, and the radiation plate facing the cool black on the outside of the camera acts as a heat sink, and an effective heat transfer link is established in the middle. The mathematical description of the heat dissipation path is shown in Equation 1. Once the thermal control system is determined, the total thermal resistance R on the heat dissipation path is fixed, and the heat Q generated by the CCD is also a fixed value. To ensure the temperature T of the CCD device If _A is constant, it is required that the temperature T _B of the radiant plate as a heat sink remains constant.

T _A =R·Q+T _B (1)

Since the radiant panel is located outside the camera, the radiant panel is sometimes in the shadow and sometimes under the action of solar radiation as the attitude of the camera changes. The change of the external heat flow causes the temperature of the radiant panel to change. When the temperature of the radiant panel is lower than the set value Heating can be used to keep the temperature constant, but when the temperature of the radiant panel is higher than the set value, it is difficult to ensure that the temperature of the CFPA is stable.

Contents of the invention

The purpose of the present invention is to propose a thermal switch for the space camera thermal control system, to overcome the disadvantage that the temperature of the detection device CCD focal plane assembly (CFPA) in the current space camera is difficult to control, and effectively ensure the stability of the space camera work .

The thermal switch used in the thermal control system of a space camera includes a left heat conduction block (1), a right heat conduction block (3), and a movable left and right between the left heat conduction block (1) and the right heat conduction block (3). Heat conduction block (2), telescopic rod (4) and spring (6); Described left heat conduction block (1) and right heat conduction block (3) are all provided with the blind hole that opens to movable heat conduction block (2), described The telescopic rod (4) and the left heat conduction block (1) are arranged in the blind hole of the left heat conduction block (1) in a sliding fit, and its two ends are fixedly connected to the bottom of the left heat conduction block (1) blind hole and the movable heat conduction block respectively. (2) above; the spring (6) is arranged in the blind hole of the right heat conduction block (3), and its two ends respectively abut against the bottom of the blind hole of the right heat conduction block (3) and the movable heat conduction block (2);

The telescopic rod (4) is made of a material whose linear coefficient of thermal expansion is greater than that of the left and right heat conduction blocks and the movable heat conduction block.

The using method and working principle of thermal switch of the present invention are:

The left and right heat conduction blocks of the thermal switch of the present invention are respectively connected with two radiation plates arranged on both sides of the space camera through heat pipes, and the movable heat conduction block is connected with the CFPA of the CCD of the space camera through flexible heat conduction pipes. The heat generated when the CCD is working is conducted to the movable heat conduction block of the thermal switch through the flexible heat pipe, and then conducted to the radiation plate connected to it by the left heat conduction block or the right heat conduction block to radiate and dissipate heat into space, thus establishing a system from the CCD focal plane component to the The heat transfer path of the external environment of the space.

When the radiant plate connected to the left heat conduction block is on the side facing away from the sun, due to the pressure of the spring, the movable heat conduction block is tightly pressed against the left heat conduction block and separated from the right heat conduction block. The path is from the CFPA through the movable heat conduction block, the left heat conduction block to the radiation plate connected to the left heat conduction block;

When the radiant plate connected to the left heat conduction block faces the sun due to the change of camera attitude, the temperature rises under the action of direct sunlight, and the telescopic rod of the thermal switch will elongate due to thermal expansion, pushing the movable heat conduction block away from the left heat conduction block , and pressed on the right heat conduction block, the heat conduction path at this time is from the CFPA through the movable heat conduction block, the right heat conduction block to another radiation plate connected to the right heat conduction block.

When the radiant plate connected to the right heat conduction block is facing the sun due to the change of the camera attitude again, and the radiant plate connected to the left heat conduction block is facing away from the sun, the movable heat conduction block is compressed due to the shrinkage of the telescopic rod of the thermal switch. Move the thermal block to the left and change the cooling channel again.

The thermal switch of the invention effectively solves the technical problem that it is difficult to stably control the temperature of the CCD device due to the change of the working posture of the space camera. It can be widely used in related spacecraft temperature control and other occasions.

Description of drawings

Fig. 1 is a structural schematic diagram of a thermal switch used in a thermal control system of a space camera according to the present invention;

Fig. 2 and Fig. 3 are schematic diagrams of the working principle of the thermal switch of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiment given with accompanying drawing.

Referring to Fig. 1, the thermal switch used for the thermal control system of a space camera includes a left heat conduction block (1), a right heat conduction block (3) made of Invar, between the left heat conduction block (1) and the right heat conduction block (3) The movable heat conduction block (2) that can move left and right, telescopic rod (4) and spring (6); The left heat conduction block (1) and the right heat conduction block (3) are all provided with openings to the movable heat conduction block (2 ), the telescopic rod (4) is set in the blind hole of the left heat conduction block (1) in a sliding fit with the left heat conduction block (1), and its two ends are fixedly connected to the blind hole of the left heat conduction block (1) respectively. On the bottom of the hole and on the movable heat conduction block (2); the spring (6) is arranged in the blind hole of the right heat conduction block (3), and its two ends respectively abut against the bottom of the blind hole of the right heat conduction block (3) and the movable heat conduction block. block (2);

The telescopic rod (4) is made of an aluminum alloy material whose linear coefficient of thermal expansion is greater than that of the left and right heat conduction blocks and the movable heat conduction block.

A guide rod (5) with one end fixed on the movable heat conduction block (2) is also inserted in the spring (6) to facilitate the movement and guidance of the movable heat conduction block.

The telescopic rod (4) is made into a hollowed-out dumbbell-shaped structure, so that it can produce a certain elastic deformation under relatively large pressure.

As shown in Figure 2, the normal state of the thermal switch is that the left heat conduction block (1) and the movable heat conduction block (2) are in a bonded state, and under the action of the elastic force of the spring 6, the left heat conduction block (1) and the movable heat conduction block are enlarged. The positive pressure on the contact surface of the block (2) makes the contact thermal resistance smaller. The heat overwhelming majority of CCD focal plane assembly transfers on the radiation cold plate 1 along the left channel that connects and dissipates in the space.

As shown in Figure 3, when the radiant cold plate 1 is subjected to the effect of direct solar radiation, and the temperature rises to the point that it cannot bear the effect of the heat sink, the telescopic rod 4 is elongated due to the temperature rise, and its elongation is greater than that of the left heat conduction block ( 1) and the elongation of the movable heat conduction block (2), so the telescopic rod pushes the movable heat conduction block to move to the right due to the change of its own size, causing the contact surface of the left heat conduction block (1) and the movable heat conduction block (2) to separate, The movable heat conduction block (2) is attached to the right heat conduction block (3). At this time, the heat of the CCD focal plane assembly is mainly transferred to the radiation cold plate II along the right channel and dissipated into space. When the radiant cold plate 1 continues to heat up and causes the telescopic rod 4 to continue to elongate, the bonding surface can be made closer, and the thermal resistance decreases; transsexual. And when the temperature of radiation cold plate 1 decreased, the temperature of telescopic rod 4 also reduced thereupon, and extension rod shrinks, adds the effect of spring simultaneously, and movable heat conduction block (2) returns left side and left heat conduction block (1) sticks Close back to the normal state of the thermal switch. At this time, if the radiation cold plate 1 continues to cool down, the extension rod 4 will continue to shrink, which will increase the positive pressure on the contact surface, making the contact more effective; if the temperature is further reduced, the extension rod 4 itself will undergo elastic denaturation. Further increases in stress are eliminated. Due to the structure and material characteristics of the extension rod 4, the applicable temperature range of the thermal switch is expanded in this way.

Claims (3)

1. thermal switch that is used for the space camera heat control system, it is characterized in that, comprise left heat-conducting block (1), right heat-conducting block (3), the movable heat-conducting block (2) that between left heat-conducting block (1) and right heat-conducting block (3), can move to the left and right, expansion link (4) and spring (6); Described left heat-conducting block (1) and right heat-conducting block (3) are equipped with the blind hole of opening to movable heat-conducting block (2), described expansion link (4) and left heat-conducting block (1) are in the left heat-conducting block of being arranged on of sliding fit (1) blind hole, on its two ends are connected at the bottom of left heat-conducting block (1) blind hole respectively and on the movable heat-conducting block (2); Described spring (6) is arranged in right heat-conducting block (3) blind hole, and its two ends are replaced respectively at the bottom of right heat-conducting block (3) blind hole and on the movable heat-conducting block (2);

Described expansion link (4) is made greater than the material of left and right heat-conducting block and movable heat-conducting block with coefficient of linear thermal expansion.

2. the thermal switch that is used for the space camera heat control system according to claim 1, it is characterized in that described expansion link (4) make the middle part hollow out the dumbbell shape structure.

3. the thermal switch that is used for the space camera heat control system according to claim 1 is characterized in that, also places to hold the guide rod (5) that is fixed on the movable heat-conducting block (2) one by one in described spring (6).

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