A thrust measuring device for a monopropellant thruster

Abstract

A thrust measuring device for a monopropellant thruster is disclosed to solve the problem of insufficient measurement accuracy in the prior art. The present invention comprises a reference platform and a measuring mechanism, wherein the measuring mechanism is mounted on the reference platform. The measuring mechanism comprises a thruster adapter, a force measuring assembly and a fixed frame, wherein the fixed frame is mounted on the reference platform. The force measuring assembly comprises three working sensors, an inner ring and an outer ring, wherein the three working sensors are evenly distributed and mounted in parallel between the inner ring and the outer ring. A spring pre-tightening structure is provided between the inner ring and the outer ring. The outer ring is fixed to the fixed frame, and the inner ring is connected to one end of the thruster adapter. The other end of the thruster adapter is provided with a mounting structure for mounting the thruster. The present invention achieves high-precision measurement within a thrust range of 0.5-50N by connecting three sensors in parallel and automatically calibrating them in situ, significantly improving the accuracy, efficiency and environmental adaptability of aerospace thruster testing. The present invention relates to the field of thrust measurement technology.

Description

Technical Field

[0001] The present invention relates to the technical field of thrust measurement, and in particular to a thrust measurement device for a monopropellant thruster. Background Art

[0002] Monopropellant thrusters are widely used in scenarios such as satellite attitude control and orbit maintenance, and their thrust measurement accuracy directly affects the performance of the control system. The 5N long-life monopropellant thruster is a typical low-thrust level in spacecraft attitude and orbit control systems. The measurement error of the 5N thruster must be ≤±1%, otherwise it may cause the satellite attitude deviation to exceed 0.1°; millisecond-level thrust transient response needs to be detected under pulse conditions. However, traditional thrust measurement equipment has the following problems: traditional measurement devices use separately set strain gauge or piezoelectric sensors for measurement. The sensitivity of strain gauge sensors is limited, and piezoelectric sensors are significantly affected by temperature, resulting in insufficient measurement accuracy.

[0003] In summary, existing thrust measurement equipment cannot meet the requirements of measurement accuracy, rigidity and environmental adaptability, and cannot suppress the impact of thruster installation eccentricity on measurement accuracy. Summary of the Invention

[0004] The present invention aims to solve the problem of insufficient measurement accuracy in the prior art and further proposes a thrust measurement device for a monopropellant thruster.

[0005] The technical solution adopted by the present invention to solve the above problems is:

[0006] The present invention includes a reference platform and a measuring mechanism, which is installed on the reference platform. The measuring mechanism includes a thruster adapter, a force measuring assembly and a fixed frame, which is installed on the reference platform. The force measuring assembly includes three working sensors, an inner ring and an outer ring. The three working sensors are evenly distributed and installed in parallel between the inner ring and the outer ring. A spring pre-tightening structure is provided between the inner ring and the outer ring. The outer ring is fixed to the fixed frame, the inner ring is connected to one end of the thruster adapter, and the other end of the thruster adapter is provided with a mounting structure for mounting the thruster.

[0007] Furthermore, the thruster adapter includes a plurality of connecting rods, a force measuring assembly connecting flange and a thruster connecting flange. The force measuring assembly connecting flange and the thruster connecting flange are arranged in parallel, and the force measuring assembly connecting flange and the thruster connecting flange are connected by a plurality of connecting rods. The plurality of connecting rods are evenly distributed along the circumferential direction.

[0008] Furthermore, the thrust measuring device of the monopropellant thruster also includes a water-cooled heat insulation screen, which is located on the left side of the thruster adapter frame. The water-cooled heat insulation screen is provided with a through hole for the thruster to pass through. The bottom of the water-cooled heat insulation screen is connected to the upper surface of the reference platform through a lower slide, and the top of the water-cooled heat insulation screen is connected to the fixed frame through an upper slide. The water-cooled heat insulation screen slides between the upper and lower slides along the axis of the thruster.

[0009] Furthermore, the thrust measuring device of the monopropellant thruster also includes a calibration mechanism, which is located on the right side of the measuring mechanism. The calibration mechanism includes a calibration force transmission assembly and a standard force generator. The standard force generator is connected to the calibration force transmission assembly, and the calibration force transmission assembly is connected to the thruster adapter frame through the force measuring assembly.

[0010] Furthermore, the standard force generator includes a standard sensor, a mounting support, a sensor mounting bracket, a vacuum stepper motor, a coupling, a ball screw, a linear slide and a support rod. The vacuum stepper motor is fixed on the reference platform through the mounting bracket, the output end of the vacuum stepper motor is connected to one end of the ball screw through the coupling, the linear slide is threadedly matched with the ball screw and the linear slide is slidably matched with the top surface of the mounting bracket, and a slide rail matching the linear slide is provided on the top surface of the mounting bracket; the sensor mounting bracket is fixed on the linear slide, the right end of the standard sensor is connected to the sensor mounting bracket through the support rod, and the left end of the standard sensor is connected to the calibration force transmission assembly.

[0011] Furthermore, the calibration force transmission assembly includes a force transmission rod, a linear spring and an automatic centering hemisphere. The right end of the force transmission rod is connected to the standard sensor. The linear spring and the automatic centering hemisphere are sequentially mounted on the force transmission rod from left to right and slide with the force transmission rod. One end of the linear spring abuts against the end face of the automatic centering hemisphere, and the other end is constrained by the limit portion at the left end of the force transmission rod.

[0012] The beneficial effects of the present invention are:

[0013] 1. The present invention achieves high-precision measurement in the thrust range of 0.5-50N by adopting a parallel structure of three working sensors and automatic in-situ calibration, significantly improving the accuracy, efficiency and environmental adaptability of aerospace thruster testing.

[0014] 2. The force measuring assembly of the present invention is composed of three evenly distributed working sensors. The three working sensors are fixedly connected by a stainless steel inner ring and an outer ring to ensure that the force direction of the working sensors remains consistent during the test, avoiding the nonlinear error introduced by the difference in the tension and compression calibration curves of the working sensors, so that the nonlinear error of the force measuring assembly is 1 / 2 of the nonlinear error of a single sensor. , and its stiffness is three times that of a single sensor.

[0015] 3. The present invention drives the ball screw through a vacuum stepper motor to achieve axial movement of the linear slide; a standard sensor is horizontally installed on the linear slide, and the connection and disconnection of the calibration force transmission component and the force measuring component can be automatically controlled through the movement of the linear slide. The connection or disconnection can be automatically completed in the vacuum chamber, which is convenient for direct testing without manual intervention after fully automatic calibration in the vacuum chamber.

[0016] 4. The thruster adapter, force measurement assembly, and standard sensor mounting brackets of the present invention are all designed with reference holes in their centers to achieve coaxial centering, ensuring that the directional deviation of the calibration line of the thruster and calibration mechanism is less than 0.1°, and the deviation between the calibration line and the thruster geometric center is less than 0.2mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the overall structure of the present invention (the figure shows the thruster to be tested);

[0018] Figure 2 yes Figure 1 Side view of;

[0019] Figure 3 is a schematic structural diagram of the measuring mechanism of the present invention (the figure shows the thruster to be measured);

[0020] Figure 4 It is a structural schematic diagram of the calibration mechanism of the present invention;

[0021] Figure 5 It is a structural schematic diagram of the thruster adapter frame of the present invention;

[0022] Figure 6 This is a schematic diagram of the force measurement component limit protection structure of the present invention;

[0023] Figure 7 It is a schematic structural diagram of the water-cooled heat insulation screen of the present invention;

[0024] Figure 8 It is the thrust measurement transfer path diagram of the present invention;

[0025] Figure 9 It is the thrust calibration transfer path diagram of the present invention;

[0026] Figure 10 This is a schematic diagram of the thrust calibration closed-loop control principle of the present invention;

[0027] Figure 11 This is a schematic diagram of the parallel use and sensitivity compensation principle of the force measuring assembly working sensors of the present invention.

[0028] In the figure: 1-Liquid pipeline and cable bracket; 2-Thruster; 3-Water-cooled heat shield; 4-Thruster adapter; 4-1-Connector

[0029] Connecting rod; 4-2-Force measuring assembly connecting flange; 4-3-Thruster connecting flange; 5-Force measuring assembly; 6-Fixed frame; 7-Force transmission rod; 8-Standard sensor; 9-Mounting support; 10-Reference platform; 11-Base; 12-Limit block; 13-Linear spring; 14-Automatic centering hemisphere; 15-Standard sensor mounting bracket; 16-Vacuum stepper motor; 17-Coupling; 18-Ball screw; 19-Linear slide; 20-Support rod. DETAILED DESCRIPTION

[0030] Specific implementation method 1: This implementation method proposes a thrust measurement device for a monopropellant thruster, such as Figure 1 and Figure 2 As shown, it includes a measuring mechanism, which is installed on a reference platform 10, and the reference platform 10 is fixed on a base 11 in the vacuum chamber; the measuring mechanism is used to measure the thrust of the thruster under steady-state and pulse conditions.

[0031] like Figure 3 As shown, the measuring mechanism includes a fluid pipeline and cable bracket 1, a water-cooled heat shield 3, a thruster adapter 4, a force measuring assembly 5, and a fixed frame 6. The fluid pipeline and cable bracket 1 is fixed on a reference platform 10 to constrain the direction of the propellant pipeline and cable, reduce the influence of additional forces, improve the repeatability of pipeline deformation, and reduce the influence of pipeline stiffness and vibration on thrust measurement.

[0032] like Figure 5 As shown, the thruster adapter 4 includes several connecting rods 4-1, a force-measuring assembly connecting flange 4-2, and a thruster connecting flange 4-3. The force-measuring assembly connecting flange 4-2 and the thruster connecting flange 4-3 are coaxially arranged and connected by several connecting rods 4-1. The number of connecting rods 4-1 can be three or four, and the connecting rods 4-1 are evenly distributed along the circumference. The thruster adapter 4 has sufficient strength and rigidity. Preferably, the rigidity of the thruster adapter 4 is greater than 10 times the rigidity of the inner and outer rings of the force-measuring assembly 5. The lightweight design is based on iterative finite element simulation, so as not to affect the overall dynamic performance.

[0033] like Figure 7As shown, the water-cooled heat insulation screen 3 is located on the outside of the thruster connecting flange 4-3 (away from the side of the force measuring assembly connecting flange 4-2). The water-cooled heat insulation screen 3 effectively isolates the impact of the thruster thermal radiation on the force measuring assembly 5 during the ignition process; the bottom of the water-cooled heat insulation screen 3 is connected to the upper surface of the reference platform 10 through a lower slide, and the top of the water-cooled heat insulation screen 3 is connected to the fixed frame 6 through an upper slide. The water-cooled heat insulation screen 3 is provided with a through hole for the thruster 2 to pass through. When the thruster 2 passes through the through hole on the water-cooled heat insulation screen 3 and is connected to the thruster connecting flange 4-3, the hole wall of the through hole is preferably sealed with the outer wall of the thruster 2; preferably, T-shaped sliding blocks are provided at the upper and lower ends of the water-cooled heat insulation screen 3 for sliding with the T-shaped slide grooves of the upper and lower slides; so that it can be slid and adjusted along the axis of the thruster 2 to accommodate thrusters 2 of different lengths; preferably, the water-cooled heat insulation screen 3 adopts a left and right symmetrical two-half structure, which is closed by flange bolts.

[0034] The force-measuring assembly 5 comprises three working sensors, an inner ring, and an outer ring. The inner and outer rings are coaxially arranged from left to right. The three working sensors are evenly distributed along the circumference and mounted in parallel between the inner and outer rings. The outer ring is fixed to a fixed frame 6, and the inner ring is connected to the force-measuring assembly connection flange 4-2 of the thruster adapter frame 4. A spring preload structure is installed between the inner and outer rings to provide an initial preload, ensuring that the force applied to the working sensors remains consistent during the test and avoiding nonlinear errors introduced by differences in the tensile and compressive calibration curves of the working sensors. The tiny signals from the three working sensors are converted into amplified voltage signals through amplifiers and then connected to the data acquisition system for recording and display by the measurement and control host computer.

[0035] like Figure 3 As shown, the fixed frame 6 is mounted on the reference platform 10 and connected to the outer ring of the force-measuring assembly 5. The fixed frame 6 bears the weight of the thruster 2 as well as the thrust of the thruster 2 during the test run. The fixed frame 6 has sufficient strength and rigidity. Preferably, the rigidity of the fixed frame 6 is greater than 10 times the rigidity of the inner and outer rings of the force-measuring assembly 5, so as not to affect the overall dynamic performance. The fixed frame 6 and the reference platform 10 are installed with a flatness better than 0.1mm / 100mm, a perpendicularity better than 0.1mm / 100mm, and a surface roughness less than 3.2μm.

[0036] In some embodiments, as Figure 6 As shown, fixed frame 6 is equipped with a position-limiting protection structure to constrain the position of force-measuring assembly 5 in the event of equipment failure or misoperation, ensuring that the inspected object does not suffer serious, irreversible consequences or damage. Specifically, four position-limiting blocks 12 are installed on the left side wall of fixed frame 6. These four position-limiting blocks 12 are arranged in a rectangular shape, forming a rectangular constraint frame. Each position-limiting block 12 has a groove. The outer circumference of the inner ring of force-measuring assembly 5 is positioned within the grooves of the four position-limiting blocks 12, with some clearance.

[0037] Preferably, the thruster adapter frame 4, the fixed frame 6, the limit block 12 and the inner and outer rings of the force measuring assembly 5 are all made of 0Cr18Ni9 stainless steel, which can resist corrosion from propellant and combustion products.

[0038] Preferably, the three working sensors of force-measuring assembly 5 are WMC force sensors manufactured by Interface. These can be used for static or highly dynamic measurements, exhibiting minimal deformation over the full range and a very high fundamental frequency. They are shock and vibration resistant, highly rigid, and low-mass. They offer self-compensation over a wide temperature range, minimizing thermal and temporal drift. Their fully enclosed stainless steel housing provides a compact structure and ease of integration. These sensors are ideally suited for low-force dynamic and static measurements, and were therefore selected as the working sensors for the thruster adapter. Force-measuring assembly 5 utilizes a combination of three WMC force sensors with a 22N range and a safe overload capacity of 200%.

[0039] like Figure 11 As shown, when the working sensors are used in parallel, the bridge power supplies of the three working sensors are connected in parallel, and the signal outputs are also connected in parallel. By fine-tuning the bridge supply voltage, the output sensitivity differences of the working sensors can be compensated, so that each working sensor can obtain the same "effective output sensitivity". Considering that the bridge supplies of the working sensors are connected in parallel, the working sensor with the smallest output sensitivity is directly connected to the bridge using the bridge supply power supply, and the other working sensors can be connected in series with resistors at the input end of the bridge. The force measuring assembly 5 obtained in this way averages the sensor errors, making the nonlinear error of the force measuring assembly 5 a factor of the nonlinear error of a single sensor. , and its stiffness is three times that of a single sensor. When used in parallel, the accuracy of the force measurement assembly 5 can be improved to <±0.019N, which is equivalent to ±0.038% of the 50N range.

[0040] Preferably, the amplifier of the working sensor is an SGA amplifier produced by Interface, with an accuracy of 0.03%; a variety of outputs (±10V, ±5V, 0-10V, 0-5V, 0-20mA, 4-20mA optional), which can match the digital acquisition channel of the measurement and control system; a bandwidth of 6kHz, suitable for steady-state and dynamic acquisition; and an optional 1Hz~5kHz hardware filter, which improves signal stability.

[0041] The force measuring assembly 5 of this embodiment detects the axial thrust signal transmitted by the thruster 2 through the thruster adapter 4 in real time through three working sensors arranged in parallel. The thermal radiation of the thruster 2 is isolated by the water-cooled heat shield 3. The output signal of the working sensor is amplified by the amplifier, and the thrust value is calculated by the data acquisition system.

[0042] In some embodiments, the thrust measurement link adopts Figure 8 The mechanical transmission path shown in the figure shows that when the thruster 2 is working, the high-speed airflow generates a reaction thrust.F , transmitted to the force measuring assembly 5 through the thruster adapter 4, the sum of the reaction forces of the three working sensors on the force measuring assembly 5 Fg Collected by the measurement and control system, Fg The force is transmitted to the fixed frame 6 and the reference platform 10 to offset the force. At the same time, the thruster 2 is restrained by the hydraulic pipeline and the cable 1. Fpi And the comprehensive effect of thermal effect on working sensor and structural thermal stress∑ Fti The force balance analysis of the movable part of the thrust frame along the thrust axis is as follows:

[0043] F +∑ Fpi +∑ Fti = Fg (1)

[0044] Where: F —Thruster thrust; Fg —Reaction force generated by the working sensor; Fpi —The sum of the restraining reaction forces of the fluid pipelines and cables;∑ Fti —The sum of the combined effects of thermal effects. Fg Directly measure and obtain in real time when the thruster 2 is working;∑ Fpi In the in-situ static calibration correction of the thrust measurement device; Fti By providing water-cooled and heat-insulated protection for the thrust measurement device, the thermal effect is reduced to the reasonable working range of the working sensor and structural parts, making the comprehensive error of the thermal effect less than 0.1%.

[0045] Specific embodiment 2: This embodiment proposes a thrust measurement device for a monopropellant thruster, the measuring device also includes a calibration mechanism, the calibration mechanism is located on the right side of the measuring mechanism, and is installed on the reference platform 10, such as Figure 4 As shown, the calibration mechanism includes a calibration force transmission component and a standard force generator. The standard force generator is connected to the calibration force transmission component, and the calibration force transmission component is connected to the thruster adapter frame 4 through the fixed frame 6 and the force measuring component 5.

[0046] like Figure 4As shown, the standard force generator includes a standard sensor 8, a mounting support 9, a sensor mounting bracket 15, a vacuum stepper motor 16, a coupling 17, a ball screw 18, a linear slide 19, and a support rod 20. The vacuum stepper motor 16 is fixed to the reference platform 10 via the mounting support 9. The output end of the vacuum stepper motor 16 is connected to one end of the ball screw 18 via the coupling 17. The other end of the ball screw 18 is fixed to the mounting support 9 via a bracket. The linear slide 19 is threadedly engaged with the ball screw 18 and slides with the top surface of the mounting support 9. The top surface of the mounting support 9 is provided with a slide rail that cooperates with the linear slide 19. The sensor mounting bracket 15 is fixed to the linear slide 19. The right end of the standard sensor 8 is connected to the sensor mounting bracket 15 via the support rod 20. The left end of the standard sensor 8 is connected to the calibration force transmission assembly. The standard sensor 8 is a high-precision sensor with higher precision than the working sensor of the force measuring assembly 5. It is used to accurately determine the value of the standard force.

[0047] like Figure 4 As shown, the calibration force transmission assembly includes a force transmission rod 7, a linear spring 13 and an automatic centering hemisphere 14. The right end of the force transmission rod 7 is connected to the standard sensor 8. The linear spring 13 and the automatic centering hemisphere 14 are sequentially mounted on the force transmission rod 7 from left to right. The linear spring 13 and the automatic centering hemisphere 14 are coaxial with the force transmission rod 7 and slide with the force transmission rod 7. One end of the linear spring 13 abuts against the end face of the automatic centering hemisphere 14, and the other end is constrained by the limit portion at the left end of the force transmission rod 7. During installation, the right end of the force transmission rod 7 is connected to the standard sensor 8, and the left end passes through the fixed frame 6, the outer ring and the inner ring of the force measuring assembly 5 in sequence, and then passes through the force measuring assembly connecting flange 4-2 of the thruster adapter frame 4. The thrust adapter frame 4, the inner and outer rings of the force measuring assembly 5 and the fixed frame 6 are all provided with holes that match the force transmission rod 7; the automatic centering hemisphere 14 and the linear spring 13 are sequentially mounted on the force transmission rod 7, and the automatic centering hemisphere 14 is located on the left side of the inner ring of the force measuring assembly 5; the left end of the force transmission rod 7 is provided with a limit part, and the outer contour of the automatic centering hemisphere 14 is a hemispherical structure that gradually narrows from left to right, and the inner ring of the force measuring assembly 5 is provided with a limit hole that matches the shape of the automatic centering hemisphere 14.

[0048] When the calibration mechanism is operating, thruster 2 is in place but not working. The vacuum stepper motor 16 is activated to rotate the ball screw 18, displacing the linear slide 19. This in turn moves the standard sensor 8 mounted on the linear slide 19. Standard sensor 8 is connected to the force transfer rod 7. As standard sensor 8 moves with the linear slide 19 away from the force-measuring assembly 5 (to the right), the force transfer rod 7 drives the self-centering hemisphere 14 to align with the stopper hole in the inner ring of the force-measuring assembly 5. The rightward movement of the linear slide 19 pulls the force-measuring assembly 5, the thruster adapter 4, and the thruster 2 in motion. This compresses the working sensor in the force-measuring assembly 5, generating a force output. By comparing the outputs of the standard sensor 8 and the working sensor, the force transfer function of the thruster adapter 4 can be obtained. Before thrust measurement during the ignition test, the calibration force transmission assembly is disengaged from the force-measuring assembly 5, minimizing the added mass of the force-measuring link and ensuring the dynamic response speed of the thrust measurement link. When the linear slide 19 is controlled by the vacuum stepper motor 16 to move toward the force-measuring assembly 5 (leftward), the force transmission rod 7 pushes the self-centering hemisphere 14 away from the limiting holes in the inner ring of the force-measuring assembly 5, restoring the force-measuring assembly 5 to a free state without additional constraints. The movement of the linear slide 19 automatically controls the connection and disconnection of the calibration force transmission assembly from the force-measuring assembly 5, facilitating direct testing without manual intervention after fully automated calibration in the vacuum chamber. During automatic calibration, the calibration force transmission assembly transfers force between the thrust calibration mechanism and the measurement mechanism.

[0049] The vacuum stepper motor 16 and the ball screw 18 generate an axial driving force of >75N, which meets the range requirements of the calibration force. The linear slide 19 is equipped with positive and negative limit sensors for limit protection of the calibration mechanism.

[0050] The preferred standard sensor 8 is an SMT force sensor manufactured by Interface. It boasts an accuracy of 0.05%, a 10x safe overload capacity, and excellent temperature adaptability, making it particularly suitable for static calibration. Given the wide static calibration range, two different sensor specifications were selected to cover the full range: an SMT / 100N sensor for 8-50N calibration and an SMT / 10N sensor for 2-8N and 0.5-2N calibration.

[0051] The amplifier for the standard sensor uses an SGA amplifier produced by Interface, with an accuracy of 0.03%. It has a variety of outputs (±10V, ±5V, 0-10V, 0-5V, 0-20mA, and 4-20mA are optional) to match the digital acquisition channels of the measurement and control system. The bandwidth is 6kHz, suitable for steady-state and dynamic acquisition. It also has an optional 1Hz~5kHz hardware filter to improve signal stability.

[0052] The stiffness of linear spring 13 is 5 N / mm, so the total deformation for a 50 N thrust is 10 mm. According to static segmented calibration: the 8-50 N range is <±0.5%, equivalent to <±0.21 N; the 2-8 N range is <±1%, equivalent to <±0.06 N; and the 0.5-2 N range is <±0.5%, equivalent to <±0.03 N. Therefore, the displacement accuracy of the standard force generator should be less than 6 μm, and the resolution should be less than 1.2 μm.

[0053] The lead of ball screw 18 is 5mm, and the resolution of the stepper motor can reach 1μm after being subdivided 5000 times by the driver. The resolution of the equivalent load calibration force is 0.005N, which meets the accuracy requirements of static calibration.

[0054] The tiny signal of the standard sensor 8 is converted into a gain voltage signal through an amplifier, connected to the data acquisition system, and recorded and displayed by the measurement and control host computer; the automatic calibration program sends instructions to the controller of the standard force generator through the IO channel in the data acquisition system, realizing program control of multiple calibration points and multiple return calibration (no less than 6 calibration points, 1 to 3 return optional), and automatically loading and unloading the calibration point force value; the automatic calibration program automatically reads the force value at each calibration point after it stabilizes for a period of time, and then goes to the next calibration point; the entire calibration process is automatically controlled and completed, and the calibration coefficient and error are automatically calculated after completion.

[0055] Preferably, the mechanical transmission path of the thrust calibration link is as follows: Figure 9 As shown, when the thrust measurement equipment is statically calibrated, F =0, using the standard force generated by the simulated thruster Fb The force balance analysis of the movable part of the thrust frame along the thrust axis is as follows:

[0056] Fb +∑ Fpi = Fg · Kg ·Δ Ug (2)

[0057] Where: Fb —Standard force generated by the simulated thruster during static calibration; Fg —The actual force that the working sensor bears during static calibration; Fpi —The sum of the restraint reaction forces of the fluid pipelines and cables; Kg —Output sensitivity of the working sensor during static calibration; Δ Ug —The output increment of the sensor working under the standard force value.

[0058] Because Fpi When statically calibrating the thrust measurement device, the output of the working sensor of the thrust measurement system is already included. Therefore, the thrust calculation formula generated when the thruster is working can be further simplified to:

[0059] F = Fb -∑ Fti = Kg ·Δ Ug '+ e (3)

[0060] Output sensitivity of the working sensor using static calibration Kg , and the net increment of the working sensor output before and after the thruster ignition Δ Ug ', in controlling the comprehensive impact of thermal effects will be Fti As random error e Then, the thrust generated by the thruster when working can be obtained from formula (3): F .

[0061] In some embodiments, in order to improve the efficiency and control accuracy of thrust calibration, a closed-loop control method is adopted in the thrust calibration system. Figure 10 The schematic diagram of the thrust calibration automatic closed-loop control system is shown. The measurement and control system collects standard force signals and issues control commands, controlling the rotation of the stepper motor, which is converted into linear displacement via a ball screw. The calibrated force transmission component pulls the force measurement component 5, generating equivalent thrust. The feedback element is a standard sensor.

[0062] In some embodiments, during thrust calibration, the calibration program specifies the required force value. Then, the measurement and control system's IO card outputs control pulses, which in turn control the motor to apply the force. The measurement and control system's AI channel collects the standard sensor force value in real time and feeds it back to the calibration program. The calibration program compares the given value with the standard sensor force value in real time. When the difference is within the set range, the standard force is applied. Throughout the calibration process, data from the working sensor of the force measurement assembly 5 is collected and automatically recorded when the calibration is stable.

[0063] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A thrust measurement device for a monopropellant thruster, characterized in that: The invention comprises a reference platform (10) and a measuring mechanism, wherein the measuring mechanism is installed on the reference platform (10), the measuring mechanism comprises a thruster adapter frame (4), a force measuring assembly (5) and a fixed frame (6), the fixed frame (6) is installed on the reference platform (10), the force measuring assembly (5) comprises three working sensors, an inner ring and an outer ring, the three working sensors are evenly distributed and installed in parallel between the inner ring and the outer ring, a spring pre-tightening structure is provided between the inner ring and the outer ring, the outer ring is fixed to the fixed frame (6), the inner ring is connected to one end of the thruster adapter frame (4), and the other end of the thruster adapter frame (4) is provided with a mounting structure for mounting the thruster (2).

2. The thrust measurement device of a monopropellant thruster according to claim 1, characterized in that: The thruster adapter frame (4) comprises a plurality of connecting rods (4-1), a force measuring assembly connecting flange (4-2) and a thruster connecting flange (4-3), the force measuring assembly connecting flange (4-2) and the thruster connecting flange (4-3) are arranged in parallel, and the force measuring assembly connecting flange (4-2) and the thruster connecting flange (4-3) are connected via a plurality of connecting rods (4-1), and the plurality of connecting rods (4-1) are evenly distributed along the circumferential direction.

3. The thrust measurement device of a monopropellant thruster according to claim 1, characterized in that: The thrust measuring device of the monopropellant thruster further comprises a water-cooled heat insulation screen (3), the water-cooled heat insulation screen (3) being located on the left side of the thruster adapter frame (4), the water-cooled heat insulation screen (3) being provided with a through hole for the thruster (2) to pass through, the bottom of the water-cooled heat insulation screen (3) being connected to the upper surface of the reference platform (10) via a lower slide, the top of the water-cooled heat insulation screen (3) being connected to the fixed frame (6) via an upper slide, and the water-cooled heat insulation screen (3) sliding between the upper and lower slides along the axis direction of the thruster (2).

4. The thrust measurement device of a monopropellant thruster according to claim 1, characterized in that: The thrust measurement device of a monopropellant thruster further comprises a calibration mechanism, which is located on the right side of the measurement mechanism. The calibration mechanism comprises a calibration force transmission component and a standard force generator, the standard force generator is connected to the calibration force transmission component, and the calibration force transmission component is connected to the thruster adapter frame (4) via a force measuring component (5).

5. The thrust measurement device of a monopropellant thruster according to claim 4, characterized in that: The standard force generator comprises a standard sensor (8), a mounting support (9), a sensor mounting frame (15), a vacuum stepping motor (16), a coupling (17), a ball screw (18), a linear slide (19) and a support rod (20), wherein the vacuum stepping motor (16) is fixed on the reference platform (10) through the mounting support (9), the output end of the vacuum stepping motor (16) is connected to one end of the ball screw (18) through the coupling (17), the linear slide (19) is threadedly matched with the ball screw (18) and the linear slide (19) is slidably matched with the top surface of the mounting support (9), and a slide rail matched with the linear slide (19) is provided on the top surface of the mounting support (9); the sensor mounting frame (15) is fixed on the linear slide (19), the right end of the standard sensor (8) is connected to the sensor mounting frame (15) through the support rod (20), and the left end of the standard sensor (8) is connected to the calibration force transmission component.

6. The thrust measurement device of a monopropellant thruster according to claim 5, characterized in that: The calibration force transmission assembly includes a force transmission rod (7), a linear spring (13) and an automatic centering hemisphere (14). The right end of the force transmission rod (7) is connected to the standard sensor (8). The linear spring (13) and the automatic centering hemisphere (14) are sequentially mounted on the force transmission rod (7) from left to right and slide with the force transmission rod (7). One end of the linear spring (13) abuts against the end face of the automatic centering hemisphere (14), and the other end is constrained by the limit portion at the left end of the force transmission rod (7).

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