Displacement sensor for micro-Newton variable thruster

Abstract

The invention discloses a displacement sensor for a micro-Newton-level variable thruster, and belongs to the field of precision measurement. The displacement sensor comprises a polymer film substrate, a strain gate resistor and three compensation resistors, the compensation resistors are all arranged at the top section of the substrate, and the strain gate resistor is arranged at the middle section of the substrate; the length of the bottom section of the substrate is larger than the sum of the length of the top section and the length of the middle section, so that the displacement sensor is of an asymmetric U-shaped bent structure when being installed and used. During use, the displacement sensor converts the relative displacement of the two ends into the change of the bending strain of the polymer film, thereby causing the change of the resistance value of the strain gate resistor. The sensor has the characteristics of high precision, low cost and light weight, can be stably used in a wide temperature range environment, and is easy to install and suitable for various application scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precision measurement, in particular to a displacement sensor for micro-newton variable thrust. BACKGROUND

[0002] The micro-newton variable thrust can produce continuous adjustable thrust, and is mainly used for super-high precision attitude control of spacecraft and drag-free flight. The micro-newton variable thrust is composed of a Laval nozzle, a valve body, a valve core assembly, a piezoelectric driving assembly and the like. The displacement signal is an important basis for the variable thrust to control the thrust. The displacement sensor can measure the small displacement of the piezoelectric driving component in real time, so as to ensure that the adjustment action matches the expected thrust. In addition, the historical data of the displacement sensor combined with intelligent algorithms can be used to analyze the component life trend, optimize the maintenance cycle and reduce the task risk.

[0003] The displacement sensor applied to the micro-newton variable thrust needs to meet the requirements of light weight, miniaturization and good temperature environment adaptability due to the particularity of its use scene. The traditional displacement sensor is heavy in weight and large in size, thereby restricting its deep application in high-end fields such as aviation, aerospace and precision manufacturing.

[0004] Therefore, there is an urgent need for a displacement sensor for micro-newton variable thrust to solve the above technical problems. SUMMARY

[0005] The present application provides a displacement sensor for micro-newton variable thrust, which has the characteristics of high precision, light weight, miniaturization and high temperature environment adaptability. The technical scheme is as follows: On the one hand, a displacement sensor for micro-newton variable thrust is provided, which comprises one strain grid resistor and three compensation resistors fixed on a base, wherein: The compensation resistors are arranged on the top section of the base, and the strain grid resistor is arranged on the middle section of the base; The length of the bottom section of the base is greater than the sum of the lengths of the top section and the middle section, so that the displacement sensor presents an asymmetric U-shaped bending structure when in use, so that the maximum bending position of the displacement sensor moves significantly with the increase of displacement, and moves from a position far away from the strain grid resistor to the position of the strain grid resistor, finally resulting in a large change in the resistance value of the strain grid resistor.

[0006] On the other hand, a method for using the displacement sensor for micro-newton variable thrust is provided, which comprises: The displacement sensor is fixedly connected at both ends to the piezoelectric driving module to be measured and the shell of the thrust, respectively; When the piezoelectric driving module generates displacement, the resistance change value of the strain grid resistor is measured by using an external circuit. determining a displacement change value of the piezoelectric drive module according to the resistance change value.

[0007] The technical scheme provided by the present application can bring at least the following beneficial effects: the substrate is made of an insulating polymer composite film, the strain gate resistor and the compensation resistor are both fixed on the substrate, and different parts of the substrate are designed to correspond to different lengths, so as to form a displacement sensor with an asymmetric U-shaped bending structure. The sensor has a simple preparation process, low cost, and is easy to mass-produce. In addition, due to the good flexibility and small stress of the overall structure, the sensor can be fixed in the thruster by adhesive, realizing non-invasive integration, without complex processes such as welding, shortening the installation time, easy to install, and avoiding potential damage to the precise structure of the thruster caused by welding thermal stress. It is especially suitable for sensitive scenarios such as spacecraft propulsion systems. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0009] Figure 1 is a displacement sensor structure schematic diagram for a micro-cow level variable thrust engine provided by an embodiment of the present application; Figure 2 is a strain gate resistor and compensation resistor circuit connection diagram provided by an embodiment of the present application; Figure 3 is a displacement sensor arrangement and strain gate resistor stress schematic diagram provided by an embodiment of the present application.

[0010] Reference signs: 1-strain gate resistor; 2, 3, 4-compensation resistor; 5-polymer substrate; 6-piezoelectric driver; 7-outer shell. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0012] As mentioned above, the common limitations of the existing displacement sensor technology include heavy mass and large volume, which restricts its deep application in high-end fields such as aerospace and precision manufacturing.

[0013] Based on this, the concept of the present application is to provide a displacement sensor for micro-newton variable thrust, which is small in size, light in mass, easy to install, and has high temperature adaptability.

[0014] The specific implementation of the above concept is described below.

[0015] Please refer to Figure 1 The displacement sensor for micro-newton variable thrust provided by the embodiment of the present application comprises a polymer film substrate, one strain grid resistor and three compensation resistors, wherein: The compensation resistors are arranged on the top section of the substrate, and the strain grid resistor is arranged on the middle section of the substrate. In use, the displacement sensor converts the relative displacement of the two ends into the change of the bending strain of the polymer film, thereby causing the resistance value of the strain grid resistor to change.

[0016] The specific implementation of the above concept is described below. Figure 1 Each part is shown.

[0017] In the embodiment of the present application, the strain grid resistor and the compensation resistor are connected according to the Wheatstone bridge as shown in Figure 2 to compensate for the temperature of the strain grid resistor, and the material of the resistor can be selected from copper alloy or metal materials such as gold.

[0018] Further, the size relationship of the strain grid resistor and the compensation resistor satisfies the following formula: In the formula, R 1 is the strain grid resistor; R 2, R 3 and R 4 are compensation resistors.

[0019] In the embodiment of the present application, the polymer film selected for the substrate is a polyimide film, and its thickness is not more than 50 microns to prevent the resistance material from exceeding the elastic strain limit, and the length of the bottom section of the substrate is greater than the sum of the lengths of the top section and the middle section, so that the displacement sensor presents an asymmetric U-shaped bending structure during installation and use, and the width of the middle section of the substrate is less than the width of all other positions of the substrate, so that the maximum bending position of the displacement sensor moves significantly with the increase of displacement, and moves from a position far away from the strain grid resistor to the position of the strain grid resistor, finally causing a large change in the resistance value of the strain grid resistor.

[0020] The actual installation location of the displacement sensor is as follows: Figure 3 As shown, during the measurement process, one end A (moving element) of the displacement sensor is connected to the piezoelectric actuator, and the other end B (stationary element) is bonded to the inner wall of the thruster housing. When the piezoelectric actuator generates displacement, the coordinates of the moving element change accordingly, and the magnitude of the strain gauge resistance changes accordingly. In the initial state, the maximum bending point of the sensor is located on the right side of the strain gauge, at which point the bending strain at the strain gauge is approximately zero; after the piezoelectric actuator generates displacement, the maximum bending point is located in the strain gauge, the stress state of the strain gauge changes, and the strain gauge undergoes significant deformation from the initial state, resulting in a corresponding change in the strain gauge resistance.

[0021] Furthermore, the strain gauge resistor and compensation resistor are electrically connected to an external circuit, which is used to measure the bridge voltage change in real time, thereby calculating the value of the strain gauge resistor. Since there is a corresponding relationship between this resistance value and the displacement of the piezoelectric actuator, the displacement information of the actuator can be obtained in real time through the resistance change, thus providing key input parameters for the precise control of the thruster.

[0022] Furthermore, to ensure high resolution of the displacement sensor, the width of the strain gauge resistor must be smaller than the width at other locations. This allows for a larger strain and resistance change at the strain gauge after the same displacement change. Additionally, the lengths of the three parts satisfy L3 > L1 + L2, ensuring that the bending strain at the strain gauge is approximately zero at the initial moment. The Wheatstone bridge design ensures that the sensor can achieve temperature self-compensation over a wide temperature range, thus meeting the requirements for stable operation of the thruster over a wide temperature range.

[0023] The displacement sensor described above has the following advantages in terms of practicality: Low-cost mass production adaptability: The fabrication process is simple, low-cost, and easy to mass-produce. Based on MEMS microfabrication technology and standardized material systems (such as polyimide flexible substrates), the unit manufacturing cost is reduced by more than 60% compared with traditional metal sensors, supporting mass production.

[0024] Stress-free rapid installation technology: Due to the good flexibility and low stress of the overall structure, the sensor can be fixed inside the thruster by adhesive, achieving non-invasive integration. It does not require complex processes such as welding, shortens the installation time, is easy to install, and avoids the potential damage to the precision structure of the thruster caused by welding thermal stress. It is especially suitable for sensitive scenarios such as spacecraft propulsion systems.

[0025] Ultra-lightweight and dynamically compatible design: Adopting a thin-film structure, the overall weight is light and does not affect the motion state of the object being measured, making it suitable for a variety of application scenarios.

[0026] Wide temperature range self-compensation performance: Temperature self-compensation is achieved through the design of the Wheatstone bridge, making it suitable for wide temperature range environments.

[0027] High durability: the sensor uses mature materials for both conductive material and substrate, and the materials only undergo elastic deformation without plastic deformation during operation, so the sensor has high durability and is suitable for long-life satellite platforms.

[0028] The application further provides a displacement sensor for a micro-cow-level variable thrust engine and a use method thereof.

[0029] Specifically, the fixing connection of the displacement sensor and the piezoelectric driving module to be measured of the variable thrust engine comprises the following steps: bending the displacement sensor, bonding the top end of the substrate to a preset connection point of the piezoelectric driving module to be measured of the variable thrust engine, and bonding the bottom end of the substrate to a preset connection point of the inner wall of the shell of the variable thrust engine.

[0030] It should be noted that the specific position of the connection point can be determined according to whether the displacement sensor is in a free stress state at the initial moment.

[0031] In addition, after the preliminary parameter design is completed, before the connection point of the displacement sensor and the variable thrust engine is designed, the stress state of the entire sensor after the displacement of the piezoelectric driving assembly changes needs to be simulated by using commercial software Abaqus, so as to ensure that the strain gage of the sensor is in elastic deformation within the rated change range. If the corresponding conditions are not met, the strain gage needs to be optimized and designed.

[0032] Finally, it should be noted that, in this document, relational terms such as first, second, third, and fourth and the like can merely be used to distinguish one entity or action from another, and do not necessarily require or imply any actual relationship or order between or among the entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0033] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A displacement sensor for a micro-Newton level variable thrust generator, characterized in that, The displacement sensor comprises a polymer thin film substrate, a strain gauge resistor, and three compensation resistors, wherein: The compensation resistors are all disposed in the top section of the substrate, and the strain gauge resistors are disposed in the middle section of the substrate; In use, the displacement sensor converts the relative displacement at both ends into a change in the bending strain of the polymer film, which in turn causes a change in the resistance of the strain gauge resistor. The length of the bottom section of the base is greater than the sum of the lengths of the top section and the middle section, so that the displacement sensor presents an asymmetrical U-shaped bending structure during installation and use.

2. The displacement sensor as described in claim 1, characterized in that, The width of the middle section of the base is smaller than the width of the rest of the base to increase the curvature of the middle section.

3. The displacement sensor as described in claim 1, characterized in that, The thickness of the polymer film does not exceed 50 micrometers to prevent the resistive material from exceeding the elastic strain limit.

4. The displacement sensor as described in claim 1, characterized in that, The strain gauge resistor and the compensation resistor are connected via a Wheatstone bridge to provide temperature compensation for the strain gauge resistor.

5. The displacement sensor as described in claim 1, characterized in that, The relationship between the strain gauge resistor and the compensation resistor satisfies the following formula: In the formula, R 1 represents the strain gauge resistance; R 2. R 3 and R 4 are all compensation resistors.

6. The displacement sensor as described in claim 1, characterized in that, The polymer film is a polyimide film, and the resistor is made of constantan alloy or gold.

7. The displacement sensor as described in claim 1, characterized in that, It also includes external circuitry: The external circuit is electrically connected to the strain gauge resistor and the compensation resistor. The external circuit is used to measure the change in bridge voltage in real time, and then calculate the magnitude of the strain gauge resistor to obtain the real-time displacement of the target under test.

8. A method for using a displacement sensor in a micro-Newton level variable thrust generator, characterized in that, Applied to the displacement sensor as described in any one of claims 1-4, the method comprises: The displacement sensor is fixedly connected to the piezoelectric drive module to be measured of the thruster; When the piezoelectric drive module generates displacement, the resistance change of the strain gauge resistor is measured using an external circuit. The displacement change value of the piezoelectric drive module is determined based on the resistance change value.

9. The method as described in claim 8, characterized in that, The displacement sensor is fixedly connected to the piezoelectric drive module to be measured in the thruster, including: After bending the displacement sensor, the top section of the base is bonded to the preset connection point of the piezoelectric drive module of the thruster under test, and the bottom section of the base is bonded to the preset connection point of the inner wall of the outer shell of the thruster under test.

10. The method as described in claim 8, characterized in that, Before designing the connection point between the displacement sensor and the thruster, the following steps are also included: The displacement sensor was simulated and optimized using Abaqus software so that the strain gauge resistor remained in an elastic deformation state within the rated displacement range of the piezoelectric drive module.

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