Ionic liquid damping module for micro thrust measuring device of electric thruster

Abstract

The invention provides an ionic liquid damping module for a micro thrust measuring device of an electric thruster. The ionic liquid damping module comprises an ionic liquid storage tank, ionic liquid, a conduction force arm and a resistance piece. The module is used for rapidly attenuating the vibration of the movable frame of the micro thrust measuring device when the electric thruster works to generate thrust, rapidly obtaining a thrust value, improving the response characteristic of thrust measurement of the micro thrust measuring device, and reducing the vibration and measurement noise of the movable frame of the thrust frame caused by the vibration of vacuum equipment and the like at ordinary times. The module can quickly attenuate the oscillating motion of the moving frame of the micro thrust measuring device in any direction, and has the characteristics of good damping effect, basically non-volatile ionic liquid, high reliability, no electromagnetic action with the electric thruster, no interference on the work of the thruster, easiness in operation, maintenance and long-term use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-thrust measurement of space electric thrusters, in particular to an ionic liquid damping module for a micro-thrust measurement device of an electric thruster. BACKGROUND

[0002] In the current research and application of space electric propulsion technology, micro-thrust measurement is a key link for evaluating the performance of electric thrusters. With the development of electric propulsion systems towards high specific impulse and micro-newton to millinewton thrust range, higher requirements are put forward for the precision, stability and response speed of thrust measurement. Traditional micro-thrust measurement devices are easily disturbed by complex environmental vibration and noise, resulting in low signal-to-noise ratio and difficult measurement.

[0003] Most of the traditional structure (such as torsion type, pendulum type or balance type) measurement devices use magnetic damping mechanisms based on permanent magnets or electromagnets. The magnetic field strength and distribution of such mechanisms need to be accurately controlled, otherwise the magnetic field may interfere with the operation of the electric thruster or affect the operation of the thrust measurement sensor, reducing the reliability of the whole machine and increasing the design difficulty and processing cost.

[0004] Patent document CN108036888B discloses a micro-thrust measurement device based on a torsion pendulum, which sets a thruster and a damping rod at both ends of a lever respectively, and uses the principle of torque balance to measure force. The damping rod extends into an oil tank, and there is a Newtonian fluid with controllable flow rate in the oil tank. The viscous force of the fluid on the damping rod generates a torque balanced with the thrust of the thruster, thereby realizing thrust measurement. The disadvantage is that the measurement medium of the thruster uses the viscous force of the flowing fluid, and the fluid properties are easily affected by environmental fluctuations, affecting the measurement accuracy. Moreover, unlike the present application, the patent document fails to exert the damping effect of the fluid on the moving frame. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide an ionic liquid damping module for a micro-thrust measurement device of an electric thruster.

[0006] According to the present application, an ionic liquid damping module for a micro-thrust measurement device of an electric thruster is provided, which comprises: ionic liquid, ionic liquid storage tank, conductive force arm and resistance sheet. The ionic liquid is contained in the ionic liquid storage tank. One end of the conductive force arm is connected to the moving frame of the micro-thrust measurement device of the electric thruster, the other end is fixedly connected to the resistance sheet, and the conductive force arm and the resistance sheet jointly extend into the ionic liquid storage tank, so that the resistance sheet is immersed in the ionic liquid. The moving frame has an oscillation state and a balance state, when the moving frame is in the oscillation state, the conductive force arm transmits the vibration of the moving frame to the resistance sheet, the displacement and the swing oscillation of the moving frame are inhibited through the viscous interaction between the resistance sheet and the ionic liquid, until the moving frame recovers from the oscillation state to the balance state.

[0007] Preferably, the ionic liquid can keep liquid state in the vacuum environment and corresponding temperature of the electric thruster test, the viscosity of the ionic liquid is not less than 34 mPa·s at room temperature 25℃, and the saturated vapor pressure is less than 10 -6 Pa.

[0008] Preferably, the top of the ionic liquid storage tank is provided with an opening, the conductive force arm extends radially above the opening, and the resistance sheet extends into the ionic liquid storage tank through the opening; The height of the opening is higher than the liquid level of the ionic liquid, and the vertical distance between the edge of the opening and the liquid level of the ionic liquid is not less than a preset height, so as to prevent the ionic liquid from splashing out.

[0009] Preferably, the conductive force arm and the resistance sheet are vertically fixedly connected to form an L-shaped structure, and the connection position of the conductive force arm and the resistance sheet is axially aligned with the opening of the ionic liquid storage tank. When the moving frame is in the balance state, the conductive force arm and the opening of the ionic liquid storage tank are axially separated by a preset distance.

[0010] Preferably, the resistance sheet includes an X-direction resistance surface, a Y-direction resistance surface and a Z-direction resistance surface. One end of the X-direction resistance surface is connected to the conductive force arm, the other end is connected to the Y-direction resistance surface and is perpendicular to the Y-direction resistance surface, and the Z-direction resistance surface is connected to the end of the Y-direction resistance surface away from the X-direction resistance surface and is perpendicular to the X-direction resistance surface and the Y-direction resistance surface.

[0011] Preferably, after the moving frame recovers from the oscillation state to the balance state, the conductive force arm and the resistance sheet are both in a separated state from the ionic liquid storage tank.

[0012] Preferably, the conductive force arm and the resistance sheet are made of 316L stainless steel or TC4 titanium alloy.

[0013] Preferably, the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium bis-trifluoromethanesulfonimide.

[0014] Preferably, the inner diameter of the ionic liquid storage tank is 5 cm, the wall thickness is 2 mm, and the height is 8-10 cm. The height of the liquid level of the ionic liquid from the bottom of the ionic liquid storage tank is 5-7 cm. The material of the ionic liquid storage tank is glass or polytetrafluoroethylene.

[0015] Preferably, the diameter of the conductive force arm is 5-6mm, and the length is 10-12cm; The thickness of the resistance sheet is 0.3mm, wherein the width of the X-direction resistance surface and the Y-direction resistance surface is 5mm, and the height is 10mm, the width of the Z-direction resistance surface is 5mm, and the length is 10mm.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1. By introducing the ionic liquid damping module, the displacement / oscillation of the yoke due to the working of the electric thruster and the multi-directional vibration caused by the vibration of the vacuum chamber are efficiently inhibited, the background noise interference is reduced, and the response speed of the thrust measurement is improved.

[0017] 2. By using the ionic liquid with stable performance and not easy to volatilize under vacuum and the simple module structure without active control, long-term and stable vacuum environment thrust measurement is realized, and the reliability and maintenance convenience of the device are improved.

[0018] 3. By replacing the traditional magnetic damping with ionic liquid damping, the electromagnetic interference of the magnetic field on the electric thruster and the measurement sensor is avoided, and the measurement accuracy is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings: Figure 1 Figure 1 is a structural schematic diagram of the ionic liquid damping module according to the present application; Figure 2 Figure 2 is a structural schematic diagram of the ionic liquid damping module according to the present application; Figure 3 Figure 3 is a schematic diagram of the resistance sheet according to the present application.

[0020] Shown in the figure: DETAILED DESCRIPTION

[0021] The present application will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of changes and improvements can be made. These all belong to the protection scope of the present application.

[0022] The application file provides an ionic liquid damping module for an electric thruster micro-thrust measuring device. The core components include ionic liquid 1, ionic liquid tank 2, conductive force arm 9 and resistance sheet 3, and form a cooperative relationship with the moving frame 4, the fixed frame 8 and the electric thruster 7 of the measuring device. Among them, the electric thruster 7 is installed on the moving frame 4, which can convert the thrust generated by the electric thruster 7 into its own displacement. The moving frame 4 is movably connected with the fixed frame 8, and the electric thruster 7 will cause the moving frame 4 to oscillate relative to the fixed frame 8. The oscillating moving frame 4 is the damping object of the damping module. The conductive force arm 9 is fixed at one end of the moving frame 4 and connected at the other end with the resistance sheet 3, and both of them are inserted into the ionic liquid tank 2 containing ionic liquid 1, and the resistance sheet 3 is immersed in the ionic liquid 1.

[0023] The ionic liquid 1 is selected from a type with specific physical parameters. Specifically, at room temperature (25℃), its viscosity is not less than 34 mPa·s, and the saturated vapor pressure is less than 10 -6 Pa. Taking water as a reference, under the same conditions, the viscosity is 0.89 mPa·s, and the saturated vapor pressure is 3169 Pa. Compared with water, the ionic liquid 1 has the physical properties of high viscosity, extremely low saturated vapor pressure and almost no volatility. The ionic liquid 1 can remain in a liquid state and has stable chemical properties under the vacuum environment and corresponding temperature of the electric thruster test, and has good compatibility with the resistance surfaces of the ionic liquid tank 2, the conductive force arm 9 and the resistance sheet 3. As the core damping medium of the module, the ionic liquid 1 directly absorbs and dissipates the vibration energy transmitted by the resistance sheet 3, which is a key component to achieve high-efficiency damping effect.

[0024] The ionic liquid tank 2 adopts a top opening structure, which has a semi-sealing effect. The opening is vertically upward, and the opening diameter can be equal to or less than the diameter of the ionic liquid tank 2. This design can avoid the structure damage caused by the impact of the conductive force arm 9 on the bottle opening during the radial movement. The conductive force arm 9 can extend radially along the ionic liquid tank 2 to above the opening, and the resistance sheet 3 extends into the ionic liquid tank 2 through the opening. The edge of the opening is higher than the preset height of the ionic liquid 1 liquid surface by not less than 2 cm, which can effectively prevent the ionic liquid 1 from splashing out of the ionic liquid tank 2 due to vibration in the vacuum environment. The ionic liquid 1 itself has a saturated vapor pressure close to zero, and its long-term evaporation in vacuum can be ignored, so it can meet the long-term storage requirements without additional sealing structure. The specific size and material of the ionic liquid tank 2 can be adjusted according to actual needs. Its core function is to stably contain the ionic liquid 1 and provide a reliable medium storage environment for the realization of damping effect.

[0025] The transmission arm 9 is rod-shaped and is vertically fixed to the resistance plate 3 by spot welding to form an L-shaped structure. The connection position of the two is aligned axially with the opening of the ionic liquid storage tank 2. The diameter, length, and material of the transmission arm 9 can be adjusted according to actual needs, so that the transmission arm 9 has sufficient rigidity and does not produce large-scale elastic deformation or permanent deformation when transmitting vibration. When the moving frame 4 is in a balanced state, the transmission arm 9 and the opening of the ionic liquid storage tank 2 are separated by a preset distance of 2-3 cm axially to ensure that they do not come into contact during normal operation. As an intermediate carrier for vibration transmission, the transmission arm 9 accurately transmits the oscillating mechanical energy of the moving frame 4 to the resistance plate 3, while ensuring its own structural stability and avoiding the impact of deformation on transmission efficiency.

[0026] During operation, the oscillation of the moving frame 4 is limited by the radius of the opening of the ionic liquid storage tank 2. Normal oscillation occurs when the oscillation amplitude does not exceed this radius; otherwise, it is considered large-amplitude oscillation. The contact rules between the transmission arm 9 and the resistance plate 3 are consistent. When the moving frame 4 is in equilibrium or oscillating normally, neither of them contacts the ionic liquid storage tank 2. When the moving frame 4 experiences large-amplitude oscillation, the resistance plate 3 collides with the side wall of the ionic liquid storage tank 2 along the radial direction. This collision does not cause them to stick together because the weight of the moving frame 4 is much greater than the potential adhesive force. Furthermore, both the transmission arm 9 and the ionic liquid storage tank 2 possess high rigidity, and the viscosity of the ionic liquid is insufficient to adhere the resistance plate 3 to the tank wall. After the moving frame 4 returns to equilibrium, the transmission arm 9 and the resistance plate 3 are once again separated from the ionic liquid storage tank 2.

[0027] The resistance plate 3 can be 0.3mm thick and consists of three cooperating resistance surfaces: an X-direction resistance surface 11, a Y-direction resistance surface 10, and a Z-direction resistance surface 12. The specific connection is as follows: one end of the X-direction resistance surface 11 is connected to the transmission arm 9, and the other end is perpendicularly connected to the Y-direction resistance surface 10; the Z-direction resistance surface 12 is connected to the end of the Y-direction resistance surface 10 away from the X-direction resistance surface 11, and is perpendicular to both the X-direction resistance surface 11 and the Y-direction resistance surface 10. The Z-direction resistance surface 12 can be horizontal. The dimensions of each resistance surface are fixed: the X and Y-direction resistance surfaces can be 5mm wide and 10mm high, and the Z-direction resistance surface can be 5mm wide and 10mm long. The relative positions of the three resistance surfaces can be adjusted according to installation requirements. The resistance plate 3, through its three-dimensional resistance surface, makes full contact with the ionic liquid 1, maximizing the interaction area with the liquid and efficiently transmitting the vibration from the transmission arm 9 to the ionic liquid 1. Combined with the liquid's viscosity, this achieves rapid attenuation of multi-directional vibrations. It is a key vibration damping component connecting the transmission arm and the ionic liquid. The aforementioned multi-directional vibrations, such as... Figure 3 As shown by the dashed arrows, it exists along the three axes of X, Y, and Z.

[0028] The ionic liquid damping module of this invention, as a component of the micro-thrust measurement device for electric thrusters, is installed within the vacuum chamber along with the thrust frame of the entire thrust measurement device. Specifically, it can be placed on a dedicated platform within the vacuum chamber via the thrust frame, or it can be suspended from the vacuum chamber wall. This installation structure allows vibrations generated by the vacuum chamber during operation to be transmitted to the thrust frame through the platform or suspension connection structure, thereby inducing additional multi-directional vibrations of the moving frame. These vibrations become background noise in thrust measurement, interfering with the accurate acquisition of the thrust signal. The ionic liquid damping module of this invention effectively weakens the vibrations transmitted from the vacuum chamber, comprehensively reducing the impact of background noise on thrust measurement and improving measurement accuracy.

[0029] Example 1 Figure 1 This is a schematic diagram of the structure of the ionic liquid damping module, which is mainly reflected in Embodiment 1 of the present invention. This embodiment is applicable to the micro-thrust measurement device of the electric thruster with a suspended moving frame structure.

[0030] In this embodiment, the moving frame 4 is suspended from the fixed frame 8 by the suspension member 5, and the connection point between the suspension member 5 and the fixed frame 8 is the suspension point. When the electric thruster 7 operates and generates a small thrust, the moving frame 4 swings slightly around the suspension point. After swinging to the equilibrium point, the moving frame 4 will continue to oscillate under the action of thrust, its own inertia, gravity and the suspension member 5.

[0031] The specific selection and parameters of each component are as follows: Ionic liquid 1 is 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4), and the viscosity of EMIBF4 is 38 mPa at room temperature (25℃). s, typical value of saturated vapor pressure is less than 10 -6 Pa has extremely low volatility and can be ignored.

[0032] The ionic liquid storage tank 2 is made of glass, with an inner diameter of 5cm, a height of 8cm, and a wall thickness of 2mm. The liquid surface of the ionic liquid 1 is 5cm from the bottom of the tank, and the vertical distance between the edge of the opening and the liquid surface is 3cm. Both the conductive arm 9 and the resistance plate 3 are made of 316L stainless steel. The conductive arm 9 has a diameter of 5mm and a length of 10cm. Its connection position with the resistance plate 3 is axially aligned with the opening of the ionic liquid storage tank 2, and in the balanced state, the conductive arm 9 and the opening are axially separated by a preset distance of 2cm.

[0033] This embodiment, through the combination of the specific structure and parameters described above, can quickly transfer the oscillation energy of the moving frame 4 to the ionic liquid 1 for dissipation, thereby enabling the moving frame 4 to quickly stabilize at the equilibrium point and improving the response characteristics and stability of micro-thrust measurement in a vacuum environment.

[0034] Example 2 Figure 2This is a schematic diagram of the structure of the ionic liquid damping module, which is mainly reflected in Embodiment 2 of the present invention. This embodiment is applicable to the micro-thrust measurement device of the electric thruster with blade support frame structure.

[0035] In this embodiment, the moving frame 4 is fixed to the support surface of the fixed frame 8 by the blade bracket 6. The blade of the blade bracket 6 forms a support point on the support surface of the fixed frame 8. When the electric thruster 7 generates a small thrust, the moving frame 4 swings slightly around the blade support point.

[0036] The specific selection and parameters of each component are as follows: Ionic liquid 1 uses 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (EMIIM). At room temperature (25℃), the viscosity of EMIIM is 34 mPa. s, typical value of saturated vapor pressure is less than 10 - 6 Pa has extremely low volatility and can be ignored.

[0037] The ionic liquid storage tank 2 is made of polytetrafluoroethylene (PTFE), with an inner diameter of 5cm, a height of 10cm, and a wall thickness of 2mm. The liquid surface of the ionic liquid 1 is 7cm from the bottom of the ionic liquid storage tank 2, and the vertical distance between the opening edge and the liquid surface is 3cm. The damping effect is further improved by increasing the height of the tank and the height of the liquid surface of the ionic liquid 1. The transmission arm 9 and the resistance plate 3 are both made of TC4 titanium alloy. The transmission arm 9 has a diameter of 6mm and a length of 12cm. Its connection position with the resistance plate 3 is aligned axially with the opening of the ionic liquid storage tank 2. In the balanced state, the transmission arm 9 is axially separated from the opening by a preset distance of 3cm. The length and strength of the transmission arm 9 are increased to adapt to the installation environment of the blade support structure. The TC4 titanium alloy transmission arm 9 has sufficient rigidity and can adapt to multi-directional vibration of the moving frame 4 without deformation. Combined with the ion liquid storage tank 2 with the top opening structure, it can effectively prevent the ion liquid 1 from splashing out of the tank or evaporating in a vacuum environment, further enhancing the device's adaptability to complex vibration environments. It is especially suitable for long-term, high-precision vacuum micro-thrust measurement tasks.

[0038] Both of the above implementation methods are based on ionic liquid damping to suppress vibration and improve accuracy. They are simple in structure, easy to operate, and suitable for micro-thrust measurement in a vacuum environment.

[0039] The working principle of this module is based on the viscous damping characteristics of ionic liquids: when the electric thruster 7 operates or the vacuum equipment vibrates, causing the moving frame 4 to oscillate, the mechanical energy of the vibration is transmitted to the resistance plate 3 through the transmission arm 9. The resistance plate 3 interacts with the ionic liquid 1, utilizing the high viscosity of the liquid to convert the vibration energy into heat energy for dissipation, thereby rapidly attenuating the vibration of the moving frame 4 in any direction. Ultimately, this achieves the core function of improving the thrust measurement response characteristics and stability. This module uses ionic liquid damping instead of traditional electromagnetic damping, which does not generate electromagnetic interaction with the electric thruster, avoiding interference with the thruster's operation. It also features easy maintenance and long-term use.

[0040] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An ionic liquid damping module for a micro-thrust measurement device for electric thrusters, characterized in that, include: Ionic liquid (1), ionic liquid storage tank (2), conductive lever arm (9) and resistance plate (3); The ionic liquid (1) is contained in the ionic liquid storage tank (2); One end of the transmission arm (9) is connected to the moving frame (4) of the electric thruster micro thrust measuring device, and the other end is fixedly connected to the resistance plate (3). The transmission arm (9) and the resistance plate (3) extend into the ionic liquid storage tank (2) together, so that the resistance plate (3) is immersed in the ionic liquid (1). The moving frame (4) has an oscillation state and a balance state. When the moving frame (4) is in the oscillation state, the transmission arm (9) transmits the vibration of the moving frame (4) to the resistance plate (3). The displacement and swaying oscillation of the moving frame (4) are suppressed by the viscous interaction between the resistance plate (3) and the ionic liquid (1) until the moving frame (4) recovers from the oscillation state to the balance state.

2. The ionic liquid damping module as described in claim 1, characterized in that, The ionic liquid can remain liquid in the vacuum environment and corresponding temperature tested by the electric thruster. At room temperature of 25°C, the viscosity of the ionic liquid (1) is not less than 34 mPa·s, and the saturated vapor pressure is less than 10. -6 Pa.

3. The ionic liquid damping module as described in claim 1, characterized in that, The top of the ionic liquid storage tank (2) is provided with an opening, the conductive force arm (9) extends radially to the top of the opening, and the resistance plate (3) extends into the ionic liquid storage tank (2) through the opening; The opening is higher than the surface of the ionic liquid (1), and the vertical distance between the edge of the opening and the surface of the ionic liquid (1) is not less than a preset height, so as to prevent the ionic liquid (1) from splashing out.

4. The ionic liquid damping module as described in claim 3, characterized in that, The transmission arm (9) is vertically fixedly connected to the resistance plate (3) to form an L-shaped structure, and the connection position of the transmission arm (9) and the resistance plate (3) is axially aligned with the opening of the ionic liquid storage tank (2). When the moving frame (4) is in a balanced state, the transmission arm (9) is axially separated from the opening of the ionic liquid storage tank (2) by a predetermined distance.

5. The ionic liquid damping module as described in claim 1, characterized in that, The resistance plate (3) includes an X-direction resistance surface (11), a Y-direction resistance surface (10), and a Z-direction resistance surface (12). One end of the X-direction resistance surface (11) is connected to the transmission arm (9), and the other end is connected to the Y-direction resistance surface (10) and is perpendicular to the Y-direction resistance surface (10). The Z-direction resistance surface (12) is connected to the end of the Y-direction resistance surface (10) away from the X-direction resistance surface (11) and is perpendicular to both the X-direction resistance surface (11) and the Y-direction resistance surface (10).

6. The ionic liquid damping module as described in claim 1, characterized in that, After the moving frame (4) recovers from the oscillation state to the equilibrium state, the transmission arm (9) and the resistance plate (3) remain separated from the ionic liquid storage tank (2).

7. The ionic liquid damping module as described in claim 1, characterized in that, The transmission arm (9) and the resistance plate (3) are made of 316L stainless steel or TC4 titanium alloy.

8. The ionic liquid damping module as described in claim 1, characterized in that, The ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

9. The ionic liquid damping module as described in claim 3, characterized in that, The opening edge of the ionic liquid storage tank (2) is not less than 2 cm above the liquid surface of the ionic liquid 1; The ionic liquid storage tank (2) is made of glass or polytetrafluoroethylene.

10. The ionic liquid damping module as described in claim 1, characterized in that, The diameter of the transmission arm (9) is 5-6 mm and the length is 10-12 cm; The thickness of the resistance sheet (3) is 0.3 mm, wherein the width of the X-direction resistance surface (11) and the Y-direction resistance surface (10) is 5 mm and the height is 10 mm, and the width of the Z-direction resistance surface (12) is 5 mm and the length is 10 mm.

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