Heating structure and temperature control method for catalytic bed of low-thrust airspace engine

Abstract

The invention provides a heating structure of a catalytic bed of a low-thrust airspace engine, which comprises the catalytic bed arranged on the airspace engine, the outer surface of the catalytic bed is cylindrical, an electric heater and a temperature sensor are respectively arranged on the outer surface of the catalytic bed, and the electric heater and the temperature sensor are arranged in a staggered manner; and a heat preservation and insulation layer is wrapped outside the catalytic bed to cover the electric heater and the temperature sensor, and is fixed on the catalytic bed through a fixing foil ring. The structure can monitor the lowest temperature of the catalytic bed in real time and provide the temperature level of a catalyst before an engine works; and the hot back immersion temperature of the engine during working can be monitored, and a basis is provided for on-orbit life analysis of the catalytic bed. And the heaters and the temperature sensors are backups for each other, so that the reliability of thermal control is improved. According to the temperature control method, automatic temperature control is achieved in the engine working mode and the engine storage mode, the temperature control threshold value is adjustable, frequent starting of the heater can be effectively avoided, and the reliability of thermal control is improved.

Description

Technical Field

[0001] The present invention relates to the field of engines for spacecraft propulsion systems, and in particular to a heating structure and a temperature control method for a catalyst bed of a small-thrust space engine. Background Art

[0002] Spacecraft monopropellant engines are widely used in attitude control and orbital maneuvers for satellites, spacecraft, and other spacecraft. Compared with bipropellant propulsion systems, monopropellant propulsion systems are significantly simpler and more reliable. If precious metals are used as catalysts, the catalyst bed generally needs to be preheated to about 100-300°C to ensure good performance when the engine is working.

[0003] During the operation of the engine, the engine catalyst bed will reach a high temperature of more than 800°C due to the heat return effect. The existing technology uses a "metal sleeve single-core heating wire" to heat the catalyst bed. The "metal sleeve single-core heating wire" has the disadvantages of low resistance density, requiring a small secondary power supply, and poor high-temperature insulation performance. The existing temperature measurement technology is to install the thermistor in the front bed of the catalyst bed, which is far away from the nozzle and has a low heat return temperature. By measuring the temperature of the front bed to predict the temperature level of the rear bed, it is difficult to intuitively display the temperature level of the catalyst.

[0004] In addition, a Chinese patent with publication number CN113562199A discloses a heating structure suitable for a small thrust engine of a spacecraft, including an electric heating plate, a temperature sensor, a multi-layer thermal insulation component and a thermal insulation gasket. The temperature sensor is installed on the engine injector, and the engine injector is connected to a solenoid valve. One side of the electric heating plate is installed on the solenoid valve, and the multi-layer thermal insulation component is installed on the other side of the electric heating plate; the engine injector is installed on a frame, and the thermal insulation gasket is arranged between the engine injector and the frame. This technology indirectly ensures the temperature of the engine injector by heating the solenoid valve, and the temperature control range is between -5°C and 15°C. Since the solenoid valve is heated and far away from the catalyst bed, there is a large error in the temperature control of the catalyst bed. Therefore, this structure and temperature control method are not suitable for the temperature control of the catalyst bed.

[0005] Therefore, those skilled in the art are committed to developing a heating structure and a temperature control method for a catalyst bed of a small thrust aerospace engine suitable for temperature control of the catalyst bed. Summary of the invention

[0006] The purpose of the present invention is to address the corresponding deficiencies of the prior art and to provide a heating structure and a temperature control method for a catalyst bed of a small thrust aerospace engine suitable for temperature control of the catalyst bed.

[0007] The objective of the present invention is achieved by adopting the following scheme:

[0008] A heating structure for a catalyst bed of a small-thrust aerospace engine comprises a catalyst bed arranged on the aerospace engine, wherein the outer surface of the catalyst bed is cylindrical, and an electric heater and a temperature sensor are respectively arranged on the outer surface of the catalyst bed, and the electric heater and the temperature sensor are arranged in a staggered manner; a thermal insulation layer is wrapped around the catalyst bed to cover the electric heater and the temperature sensor, and the thermal insulation layer is fixed to the catalyst bed with a fixed foil ring. This structure can monitor the lowest temperature of the catalyst bed in real time to provide the temperature level of the catalyst before the engine works; it can also monitor the heat return temperature when the engine works, and provide a basis for the on-orbit life analysis of the catalyst bed. In addition, the heaters and the temperature sensors are backed up for each other, which improves the reliability of thermal control.

[0009] Furthermore, the electric heater and the temperature sensor are both armored structures with a simple and firm structure. The electric heater is a micro electric heater with a compact structure and occupies a small space.

[0010] Furthermore, the outer surface of the catalyst bed is provided with a mounting groove for accommodating an electric heater or a temperature sensor.

[0011] Furthermore, thermal conductive silicone is applied in the installation groove. After the electric heater or temperature sensor is placed on it, the electric heater or temperature sensor is pressed with titanium foil and fixed to the catalytic bed by spot welding. The thermal conductive silicone is mainly used to enhance the thermal conductivity between the electric heater or temperature sensor and the catalytic bed, and the titanium foil fixes the outside from the outside. The structure is simple and the thermal conductivity is good.

[0012] Furthermore, the fixed foil ring is made of titanium foil wrapped around the outer surface of the thermal insulation layer, and the joints of the head and tail ends of the titanium foil are fixed by spot welding to fix the thermal insulation layer on the catalyst bed, which has a simple structure and is firmly fixed.

[0013] Furthermore, the number of the electric heater and the number of the temperature sensor are at least one each.

[0014] Furthermore, the thermal insulation layer is made of high-silica glass fiber needle-punched felt, and the small thermal conductivity of the structure can avoid the heat loss of the electric heater as much as possible, thereby improving the thermal insulation effect.

[0015] The present invention also provides a temperature control method for a catalyst bed of a small thrust aerospace engine, using the above-mentioned heating structure of the catalyst bed of the small thrust aerospace engine, and the automatic temperature control mode of the catalyst bed comprises the following steps:

[0016] 1) The temperature control threshold in the engine working mode is set to the lower limit value A1 and the upper limit value A2, and the temperature control threshold in the engine storage mode is set to the lower limit value B1 and the upper limit value B2;

[0017] 2) When the engine is in working mode, when the temperature measured by the temperature sensor is lower than the lower limit value A1, the heating circuit is powered on for heating; when the temperature measured by the temperature sensor is higher than the upper limit value A2, the heating circuit is powered off;

[0018] When the engine is in storage mode, when the temperature measured by the temperature sensor is lower than the lower limit value B1, the heating circuit is energized for heating, and when the temperature measured by the temperature sensor is higher than the upper limit value B2, the heating circuit is de-energized.

[0019] Furthermore, the lower limit value A1 is 200°C, the upper limit value A2 is 220°C, the lower limit value B1 is 0°C, and the upper limit value B2 is 10°C.

[0020] The advantages of the present invention are:

[0021] 1. The heating structure and the corresponding temperature control method of the present invention can withstand the high temperature environment of hot reimmersion, and can intuitively display the temperature of the catalyst bed to better indicate the operation of the engine.

[0022] 2. The heat insulation layer of the present invention is formed by high-silica glass fiber needle-punched felt, which has a low thermal conductivity and can avoid heat loss of the electric heater as much as possible, thereby improving the heat insulation effect.

[0023] 3. The present invention can realize automatic temperature control in both engine working mode and engine storage mode, and the temperature control threshold is adjustable, which can effectively avoid frequent startup of the heater and improve the reliability of thermal control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the catalyst bed heating structure of the present invention;

[0025] Figure 2 It is a schematic cross-sectional view of the catalyst bed heating structure of the present invention. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to understand the characteristics and effects of the present application, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the common meanings understood by those skilled in the art for the present application. In case of conflict, the definitions in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present application in any way, that is, the content of the present application can be implemented without being limited by any specific theory or mechanism.

[0028] As used herein, "this application" means "the present invention" or "the present disclosure".

[0029] The use of "one", "an", "a kind" or similar expressions to describe the components and technical features described in this application is merely for the convenience of expression and to provide a general meaning to the scope of this application. Therefore, such description should be understood to include one or at least one, and the singular also includes the plural, unless it is obvious that it refers to another meaning.

[0030] In this document, "or its combination" means "or any combination thereof", and "any one", "any one" means "any one", "any one" or "any one".

[0031] It should be understood that the features disclosed in the various embodiments herein may be arbitrarily combined to form the technical solution of the present application, as long as there is no contradiction in the combination of these features.

[0032] The present application will be described below with specific implementations and examples. It should be understood that these specific implementations and examples are merely illustrative and are not intended to limit the scope of the present application and its use.

[0033] Unless otherwise stated, the methods, reagents and conditions used in the following preparation examples, comparative examples and examples are conventional methods, reagents and conditions in the art.

[0034] Example 1

[0035] like Figure 1 and Figure 2 As shown, a heating structure of a catalyst bed of a small-thrust aerospace engine, wherein the small-thrust aerospace engine refers to an aerospace engine with a thrust less than 10N, comprises a catalyst bed 1 arranged on the aerospace engine, wherein the outer surface of the catalyst bed 1 is cylindrical, and an electric heater 2 and a temperature sensor 4 are respectively arranged on the outer surface of the catalyst bed 1, wherein the electric heater 2 and the temperature sensor 4 are staggered; a thermal insulation layer 3 is wrapped around the catalyst bed 1 to cover the electric heater 2 and the temperature sensor 4, and the thermal insulation layer 3 is fixed to the catalyst bed 1 by a fixed foil ring 6.

[0036] The number of the electric heater 2 and the temperature sensor 4 is at least one, and there can be more than one. When there is only one, the electric heater 2 and the temperature sensor 4 are arranged opposite to each other at the two ends of the catalyst bed; when there are more than one, the electric heaters 2 and the temperature sensors 4 are arranged on the catalyst bed in an equidistant manner, which has better heating effect and temperature sensing effect. Preferably, Figure 2As shown, the number of the electric heaters 2 and the temperature sensors 4 are two each, and they are staggered and arranged on the catalyst bed at equal intervals in the circumferential direction, that is, the angle between adjacent electric heaters 2 and temperature sensors 4 is 90°. According to the test and thermal simulation analysis, this staggered installation method of two each and at equal intervals heats the catalyst bed most evenly, uses the least power to achieve the same heating effect, and can save energy to the greatest extent; the temperature at the temperature sensor measuring point is the lowest, which can ensure that the temperature of all catalysts meets the requirements before the engine starts.

[0037] The electric heater 2 and the temperature sensor 4 are both armored structures. The outer surface of the catalytic bed 1 is provided with a mounting groove 5 for accommodating the electric heater 2 or the temperature sensor 4. The mounting groove 5 is coated with thermal conductive silicone. After the electric heater 2 or the temperature sensor 4 is placed, the electric heater 2 or the temperature sensor 4 is pressed with a titanium foil and fixed to the catalytic bed 1 by spot welding. Preferably, the thermal conductive silicone is GD414 silicone rubber, which has good thermal conductivity, high strength, high elongation at break, can be used for a long time within the range of -60 to 200 ° C, and has very good resistance to ultraviolet light, weather aging and excellent electrical insulation function. In this embodiment, GD414 silicone rubber is produced by Sichuan Zigong Zhonghao Chenguang Chemical Research Institute Co., Ltd. The room temperature curing of the thermal conductive silicone is not less than 24 hours. After curing, the fixed foil ring 6 is surrounded by a titanium foil on the outer surface of the thermal insulation layer 3, and the joints of the head and tail ends of the titanium foil are fixed by spot welding to fix the thermal insulation layer 3 on the catalytic bed.

[0038] Preferably, the thickness of the titanium foil in this embodiment is 0.1 mm.

[0039] Preferably, the thermal insulation layer 3 in this embodiment is made of 3 mm thick high-silica glass fiber needle felt. The high-silica glass fiber needle felt has a low thermal conductivity and can avoid heat loss of the electric heater as much as possible, thereby improving the thermal insulation effect.

[0040] Specifically, taking the installation structure in which the number of the electric heater 2 and the temperature sensor 4 are two and the installation structure is staggered at equal intervals as an example, first, four installation grooves 5 with equal intervals are processed on the circumferential outer surface of the catalyst bed 1, and GD414 silicone rubber is applied in the installation grooves 5. Then, the electric heater 2 and the temperature sensor 4 are staggered in the installation grooves 5, and the electric heater 2 or the temperature sensor 4 is pressed with a 0.1 mm thick titanium foil and fixed to the catalyst bed 1 by spot welding. After curing at room temperature for 24 hours, the fixed foil ring 6 is surrounded by a 0.1 mm thick titanium foil on the outer surface of the 3 mm thick high-silica glass fiber needle felt, and the joints of the head and tail ends of the titanium foil are fixed by spot welding to fix the high-silica glass fiber needle felt on the catalyst bed.

[0041] This embodiment also provides a temperature control method for a catalyst bed of a small thrust aerospace engine, using the above-mentioned heating structure of the catalyst bed of the small thrust aerospace engine, and the automatic temperature control mode of the catalyst bed includes the following steps:

[0042] 1) The temperature control threshold in the engine working mode is set to the lower limit value A1 and the upper limit value A2, and the temperature control threshold in the engine storage mode is set to the lower limit value B1 and the upper limit value B2, where the lower limit value A1 is 200°C, the upper limit value A2 is 220°C, the lower limit value B1 is 0°C, and the upper limit value B2 is 10°C.

[0043] 2) When the engine is in working mode, when the temperature measured by the temperature sensor 4 is lower than the lower limit value A1, i.e., 200°C, the heating circuit is powered on for heating; when the temperature measured by the temperature sensor 4 is higher than the upper limit value A2, i.e., 220°C, the heating circuit is powered off;

[0044] When the engine is in storage mode, when the temperature measured by the temperature sensor 4 is lower than the lower limit value B1, ie, 0°C, the heating circuit is powered on for heating; when the temperature measured by the temperature sensor 4 is higher than the upper limit value B2, ie, 10°C, the heating circuit is powered off.

[0045] The above-mentioned temperature control method can realize automatic temperature control in both engine working mode and engine storage mode, and the temperature control threshold is adjustable, which can effectively avoid frequent startup of the heater and improve the reliability of thermal control.

[0046] The heating structure of the present invention can monitor the minimum temperature of the catalyst bed in real time to provide the temperature level of the catalyst before the engine works; it can also monitor the heat return temperature when the engine works to provide a basis for the on-orbit life analysis of the catalyst bed. The heaters and temperature sensors are backed up for each other, which improves the reliability of thermal control. The heating structure of the present invention and the corresponding temperature control method can withstand the high temperature environment of heat return, and can intuitively display the temperature of the catalyst bed to better indicate the operation of the engine.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A heating structure for a catalyst bed of a small thrust aerospace engine, comprising a catalyst bed (1) arranged on the aerospace engine, wherein the outer surface of the catalyst bed (1) is cylindrical, and characterized in that: The outer surface of the catalyst bed (1) is provided with an electric heater (2) and a temperature sensor (4), respectively, and the electric heater (2) and the temperature sensor (4) are arranged in a staggered manner; a thermal insulation layer (3) is wrapped around the catalyst bed (1) to cover the electric heater (2) and the temperature sensor (4), and the thermal insulation layer (3) is fixed to the catalyst bed (1) by a fixing foil ring (6).

2. The heating structure of the catalyst bed of a low-thrust aerospace engine according to claim 1, characterized in that: The electric heater (2) and the temperature sensor (4) are both armored structures.

3. The heating structure of the catalyst bed of a low-thrust aerospace engine according to claim 1, characterized in that: The outer surface of the catalytic bed (1) is provided with a mounting groove (5) for accommodating an electric heater (2) or a temperature sensor (4).

4. The heating structure of the catalyst bed of a low-thrust aerospace engine according to claim 3, characterized in that: The installation groove (5) is coated with heat-conducting silica gel, and after the electric heater (2) or the temperature sensor (4) is placed, the electric heater (2) or the temperature sensor (4) is pressed with a titanium foil and fixed to the catalyst bed (1) by spot welding.

5. The heating structure of the catalyst bed of a low-thrust aerospace engine according to claim 1, characterized in that: The fixed foil ring (6) is made of titanium foil and is wrapped around the outer surface of the thermal insulation layer (3). The joints at the head and tail ends of the titanium foil are fixed by spot welding to fix the thermal insulation layer (3) on the catalyst bed.

6. The heating structure of the catalyst bed of a low-thrust aerospace engine according to claim 1, characterized in that: The number of the electric heater (2) and the number of the temperature sensor (4) are at least one each.

7. The heating structure of the catalyst bed of a low-thrust aerospace engine according to claim 1, characterized in that: The thermal insulation layer (3) is made of high-silica glass fiber needle-punched felt.

8. A temperature control method for a catalyst bed of a low-thrust aerospace engine, using the heating structure for the catalyst bed of a low-thrust aerospace engine as claimed in claim 1, characterized in that: The automatic temperature control mode of the catalyst bed includes the following steps: 1) The temperature control threshold in the engine working mode is set to the lower limit value A1 and the upper limit value A2, and the temperature control threshold in the engine storage mode is set to the lower limit value B1 and the upper limit value B2; 2) When the engine is in working mode, when the temperature measured by the temperature sensor (4) is lower than the lower limit value A1, the heating circuit is powered on for heating; when the temperature measured by the temperature sensor (4) is higher than the upper limit value A2, the heating circuit is powered off; When the engine is in storage mode, when the temperature measured by the temperature sensor (4) is lower than the lower limit value B1, the heating circuit is powered on for heating; when the temperature measured by the temperature sensor (4) is higher than the upper limit value B2, the heating circuit is powered off.

9. The temperature control method for the catalyst bed of a low-thrust aerospace engine according to claim 8, characterized in that: The lower limit value A1 is 200°C, the upper limit value A2 is 220°C, the lower limit value B1 is 0°C, and the upper limit value B2 is 10°C.

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