High-stability cold air propelling system with adjustable mass center and mass center adjusting method

Abstract

The invention relates to a mass center adjustable high-stability cold air propelling system and a mass center adjusting method, and belongs to the field of spacecraft propelling systems. Wherein the propelling system adopts a double-branch parallel design, and each branch comprises a high-pressure gas cylinder, a gas charging and discharging valve, a high-pressure pressure sensor, a high-pressure isolation self-locking valve, a throttling hole, a pressure reducer, a pressure control electromagnetic valve, a buffer gas cylinder, a low-pressure pressure sensor and a cold gas thruster; the upstream and the downstream of the two branches are respectively connected through a high-pressure through self-locking valve and a low-pressure through self-locking valve; the high-pressure pressure sensor, the high-pressure isolation self-locking valve, the pressure control electromagnetic valve, the low-pressure pressure sensor, the high-pressure through self-locking valve, the low-pressure through self-locking valve and the cold air thruster are connected with the control unit through cables. The flow is adjusted by controlling the pre-spraying pressure, the propellant consumption is controlled through matching work of the thrusters, the surplus is balanced through the self-locking valve, and the mass center adjusting function is achieved. The three functions of storage, supply and mass center adjustment of the working medium can be achieved.

Description

Technical Field

[0001] This invention relates to a highly stable cold gas propulsion system with adjustable center of mass for use on satellites and a method for adjusting the center of mass, belonging to the technical field of spacecraft propulsion systems. Background Technology

[0002] Gravity measurement satellites place ultra-precise, ultra-stable, and ultra-quiet requirements on the satellite platform. To prevent the influence of liquid sloshing on the satellite's center of mass, a high-pressure cold gas propulsion system is generally used for the satellite's attitude and orbit control.

[0003] In currently used cold gas propulsion systems, mechanical pressure reducers or electronic pressure reducers are generally used to reduce the pressure of high-pressure gas. However, mechanical pressure reducers have inherent drawbacks such as low pressure reduction accuracy, low pressure reduction ratio, large weight, and short lifespan, making them unsuitable for long-life satellites. Electronic pressure reducers are less adaptable to input pressures above 20 MPa. Furthermore, previous propulsion systems did not consider the stability of the center of mass. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a highly stable cold air propulsion system and a center of mass adjustment method with adjustable center of mass. It fully combines the advantages of mechanical decompression and electronic decompression, and completes the center of mass adjustment by first-stage mechanical decompression to resist impact and second-stage electronic decompression to stabilize output.

[0005] The technical solution adopted in this invention is: A highly stable cold gas propulsion system with adjustable center of mass is used for attitude control and orbit control of a satellite during its on-orbit operation. The system adopts a dual-branch parallel design, with both branches operating simultaneously during on-orbit operation. The system includes a first branch, a second branch, a high-pressure through-locking valve, a low-pressure through-locking valve, and a control unit. The first and second branches have the same composition, both including a high-pressure gas cylinder, a gas filling and releasing valve, a high-pressure pressure sensor, a high-pressure isolation self-locking valve, a throttle orifice, a pressure reducer, a pressure control solenoid valve, a buffer gas cylinder, a low-pressure pressure sensor, and a cold gas thruster; the upstream and downstream of the two branches are connected by a high-pressure through-locking valve and a low-pressure through-locking valve, respectively; the high-pressure pressure sensor, the high-pressure isolation self-locking valve, the pressure control solenoid valve, the low-pressure pressure sensor, the cold gas thruster, the high-pressure through-locking valve, and the low-pressure through-locking valve are connected to the control unit via cables; During ground refueling, high-pressure gas is injected into the high-pressure gas cylinder through the gas filling and emptying valves of the two branches; During on-orbit operation, the control unit drives the high-pressure isolation self-locking valve to open, allowing the high-pressure gas in the high-pressure cylinder to be reduced to the target pressure via a pressure reducer, i.e., the first-stage mechanical pressure reduction. The control unit controls the pressure control solenoid valve to fill the buffer cylinder with gas. The low-pressure sensor monitors the gas pressure in the buffer cylinder in real time and feeds the test data back to the control unit. When the pressure in the buffer cylinder is lower than the lower limit of the target pressure, the control unit drives the pressure control solenoid valve to open with a set pulse width to replenish gas. When the pressure in the buffer cylinder is higher than the upper limit of the target pressure, the pressure control solenoid valve remains closed, thereby controlling the pressure in the buffer cylinder to remain stable within the target low-pressure range, i.e., the second-stage electronic pressure reduction. The control unit controls the cold gas thruster to operate, and the gas in the buffer cylinder is ejected from the cold gas thruster to generate stable thrust, enabling the propulsion system to operate normally. In both the first and second branches, a throttling orifice is provided upstream of the pressure reducer to reduce the impact of high-pressure gas on the pressure reducer. After operating in orbit for a period of time, the remaining amount of high-pressure gas cylinders in the two branches will differ. The difference in the remaining amount of the two high-pressure gas cylinders is monitored by the high-pressure pressure sensors connected to each cylinder and the signals are transmitted to the control unit. When the cumulative error reaches the set threshold, the control unit controls the opening of the high-pressure through-lock valve to balance the two high-pressure gas cylinders and maintain the stability of the overall center of mass.

[0006] Furthermore, in the first branch, the throttling orifice provided upstream of the pressure reducer is defined as the first throttling orifice; The outlet of the first gas filling and exhaust valve, the inlet of the first high-pressure pressure sensor, and the inlet of the first high-pressure isolation self-locking valve are all connected to the outlet of the first high-pressure gas cylinder. The inlet of the first throttle orifice is connected to the outlet of the first high-pressure isolation self-locking valve. The outlet of the first throttle orifice is connected to the inlet of the first pressure reducer. The outlet of the first pressure reducer is connected to the inlet of the first pressure control solenoid valve. The outlet of the first pressure control solenoid valve is connected to the inlet of the first buffer gas cylinder and the inlet of the first low-pressure pressure sensor. The outlet of the first buffer gas cylinder is connected to the inlet of the first cold air thruster of each branch.

[0007] Furthermore, in the second branch, the throttling orifice located upstream of the pressure reducer is defined as the second throttling orifice; The outlet of the second gas supply and exhaust valve, the inlet of the second high-pressure pressure sensor and the inlet of the second high-pressure isolation self-locking valve are all connected to the outlet of the second high-pressure gas cylinder. The inlet of the second throttle orifice is connected to the outlet of the second high-pressure isolation self-locking valve. The outlet of the second throttle orifice is connected to the inlet of the second pressure reducer. The outlet of the second pressure reducer is connected to the inlet of the second pressure control solenoid valve. The outlet of the second pressure control solenoid valve is connected to the inlet of the second buffer gas cylinder and the inlet of the second low-pressure pressure sensor. The outlet of the second buffer gas cylinder is connected to the inlet of the second cold air thruster of each branch.

[0008] Furthermore, both branches employ mechanical pressure regulators; both branches utilize a primary mechanical pressure reduction followed by a secondary electronic pressure reduction mode to regulate system pressure, specifically: In the first branch, the first pressure reducer and the first pressure control solenoid valve work together to reduce pressure; In the second branch, the second pressure reducer works in conjunction with the second pressure control solenoid valve to achieve pressure reduction.

[0009] Furthermore, the connections between the components within the first branch, the components within the second branch, the high-pressure through-locking valve and the two branches, and the low-pressure through-locking valve and the two branches are all achieved through pipelines. The pipelines are connected by welding or by a metal ball head-metal conical surface screw connection hard seal.

[0010] Furthermore, in the propulsion system, the first branch and the second branch back each other up, and the other branch performs basic functions in the event of a single branch failure. In the event of a single branch failure only in the pressure reduction stage, i.e., a failure of the pressure reducer or the pressure control solenoid valve, the high-pressure through-lock valve and the low-pressure through-lock valve are opened by the control unit to enable simultaneous consumption of gas from both branch cylinders and pairing of the two branch cold gas thrusters under failure conditions, thus ensuring thrust supply under the normal center of gravity adjustment function of the system.

[0011] Furthermore, one end of the high-pressure through-lock valve is connected to the outlet of the first high-pressure gas cylinder in the first branch, and the other end of the high-pressure through-lock valve is connected to the outlet of the second high-pressure gas cylinder in the second branch; one end of the low-pressure through-lock valve is connected to the outlet of the first buffer gas cylinder in the first branch, and the other end of the low-pressure through-lock valve is connected to the outlet of the second buffer gas cylinder in the second branch.

[0012] Secondly, the present invention also proposes a method for center-of-mass adjustment based on the aforementioned highly stable cold gas propulsion system with adjustable center of mass, comprising: The first step is to adjust the flow rate by controlling the pre-spray pressure, thereby adjusting the centroid. The second step is to adjust the center of gravity by controlling the propellant consumption through thruster pairing. The third step is to adjust the center of gravity by controlling the self-locking valve through the control unit to balance and adjust the remaining amount of high-pressure gas cylinder.

[0013] Furthermore, the adjustment of the centroid by controlling the pre-spray pressure and adjusting the flow rate specifically involves: During on-orbit operation, based on the difference in average specific impulse performance between the two branches of the cold gas thruster, a matching buffer cylinder pressure, i.e., the pre-jet pressure of the cold gas thruster, is set to minimize the difference in outlet flow rate between the two branches. The calculation formula for setting the buffer cylinder pressure is as follows:

[0014] Among them, (LP) i , Isp i T i F i Let i represent the pressure of the buffer cylinder in the i-th branch, the outlet mass flow rate, the average specific impulse, the pressure of the buffer cylinder, and the average thrust, respectively, i=1,2; R Let A be the ideal gas constant, γ be the adiabatic index of the gas, and A be the adiabatic index of the gas. t The cross-sectional area of ​​the thruster throat; the pressure of the buffer cylinder is reset by controlling the opening and closing of the solenoid valve through the control unit.

[0015] Furthermore, the method of adjusting the center of mass by controlling propellant consumption through thruster pairing specifically involves: Propellant consumption is controlled by pairing cold gas thrusters: During system design and integration, cold gas thrusters with thrust deviation within ±5% are selected for pairing and installation, that is, the cold gas thruster Aj of the first branch is paired and installed with the cold gas thruster Bj of the second branch, and the thrust deviation between the two cold gas thrusters is controlled within ±5%, j=1,2,…,n; During on-orbit operation, the paired cold gas thrusters work simultaneously, that is, the first branch cold gas thruster Aj and the second branch cold gas thruster Bj work at the same time; in this way, the propellant consumption of the two branches of the cold gas propulsion system is balanced, thereby achieving the function of center of mass control.

[0016] Furthermore, the method of adjusting the center of gravity by controlling the self-locking valve through the control unit to balance the remaining amount of high-pressure gas cylinder is as follows: After operating in orbit for a period of time, due to the accumulation of system errors, the remaining amount in the dual-branch high-pressure cylinders will differ. The difference in the remaining amount in the two branch high-pressure cylinders is monitored by the high-pressure sensors connected to each branch and the signals are transmitted to the control unit. When the cumulative error reaches the set threshold, the control unit controls the opening of the high-pressure through-lock valve to balance the two high-pressure gas cylinders and maintain the stability of the overall center of mass.

[0017] Furthermore, the difference in the remaining amount in the two high-pressure gas cylinders is calculated using the following formula:

[0018] Where Δm is the difference in the remaining amount in the two high-pressure gas cylinders, M is the molar mass of the gas, R is the ideal gas constant, (HP)1, V1, and T1 are the pressure, volume, and temperature of the first high-pressure gas cylinder, respectively, and (HP)2, V2, and T2 are the pressure, volume, and temperature of the second high-pressure gas cylinder, respectively.

[0019] The advantages of this invention compared to the prior art are: (1) The high-stability cold gas propulsion system and method with adjustable center of mass proposed in this invention are significantly different from the previous pure mechanical or pure electronic storage and supply devices. It adopts a mechanical and electronic decompression mode, with first-stage mechanical decompression to resist impact and second-stage electronic decompression to stabilize output. It has the advantages of good on-orbit applicability, high pressure resistance, high precision, large decompression ratio, long life and high reliability, and has the function of center of mass adjustment. (2) The high-stability cold gas propulsion system and method with adjustable center of mass proposed in this invention proposes a pipeline throttling orifice design to effectively reduce the impact of high-pressure gas on the pressure reducer, reduce the failure rate of the system, and increase the reliability and service life of the system. (3) The high-stability cold gas propulsion system and method with adjustable center of mass proposed in this invention improves the pressure reduction ratio of "gas source pressure / output pressure" of the pressure reduction system. The dual gas source inlet and dual pressure reduction outlet design provides two gas source inlets and two gas outlets at the same time. The center of mass is stabilized through a two-step center of mass adjustment mode. It has strong practicality and system reliability, and has wide applicability to the precise pressure reduction and stable adjustment of spacecraft propulsion systems. (4) The high-stability cold gas propulsion system and method with adjustable center of mass proposed in this invention can be extended to pressure regulation modules such as the gas path part of high-pressure cold gas propulsion system, electric propulsion system, and bi-component propulsion system of spacecraft; in addition, the mechanical and electronic decompression system proposed in this invention can also be extended to the precise pressure control of high-pressure gas systems used on the ground. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the high-stability cold gas propulsion system with adjustable center of mass of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments.

[0022] like Figure 1 As shown, this invention proposes a highly stable cold gas propulsion system with an adjustable center of mass for attitude and orbit control of a satellite during its on-orbit operation. It employs a dual-branch parallel design, with both branches operating simultaneously during on-orbit operation. The system includes a first branch, a second branch, a high-pressure through-lock valve 3, a low-pressure through-lock valve 20, and a control unit. The first and second branches have the same composition, both including a high-pressure gas cylinder, a gas filling and releasing valve, a high-pressure pressure sensor, a high-pressure isolation self-locking valve, a throttle orifice, a pressure reducer, a pressure control solenoid valve, a buffer gas cylinder, a low-pressure pressure sensor, and a cold gas thruster; the upstream and downstream of the two branches are connected by a high-pressure through-locking valve 3 and a low-pressure through-locking valve 20, respectively; the high-pressure pressure sensor, the high-pressure isolation self-locking valve, the pressure control solenoid valve, the low-pressure pressure sensor, the cold gas thruster, the high-pressure through-locking valve 3, and the low-pressure through-locking valve 20 are connected to the control unit via cables; Specifically, such as Figure 1 As shown, the first branch includes a high-pressure first high-pressure gas cylinder 1, a first gas filling and emptying valve 4, a first high-pressure pressure sensor 6, a first high-pressure isolation self-locking valve 8, a first throttle orifice 10, a first pressure reducer 12, a first pressure control solenoid valve 14, a first buffer gas cylinder 18, a first low-pressure pressure sensor 16, and a first cold air thruster 22; as shown Figure 1 In the diagram, L represents the self-locking valve category, P represents the sensor category, and S represents the solenoid valve category.

[0023] The outlet of the first gas filling and exhaust valve 4, the inlet of the first high-pressure pressure sensor 6, and the inlet of the first high-pressure isolation self-locking valve 8 are all connected to the outlet of the first high-pressure gas cylinder 1. The inlet of the first throttle orifice 10 is connected to the outlet of the first high-pressure isolation self-locking valve 8. The outlet of the first throttle orifice 10 is connected to the inlet of the first pressure reducer 12. The outlet of the first pressure reducer 12 is connected to the inlet of the first pressure control solenoid valve 14. The outlet of the first pressure control solenoid valve 14 is connected to the inlet of the first buffer gas cylinder 18 and the first low-pressure pressure sensor 16. The outlet of the first buffer gas cylinder 18 is connected to the inlet of the first cold air thruster 22 of each branch.

[0024] The second branch includes a high-pressure second high-pressure gas cylinder 2, a second gas filling and emptying valve 5, a second high-pressure pressure sensor 7, a second high-pressure isolation self-locking valve 9, a second throttle orifice 11, a second pressure reducer 13, a second pressure control solenoid valve 15, a second buffer gas cylinder 19, a second low-pressure pressure sensor 17, and a second cold air thruster 23. The outlet of the second gas supply and exhaust valve 5, the inlet of the second high-pressure pressure sensor 7, and the inlet of the second high-pressure isolation self-locking valve 9 are all connected to the outlet of the second high-pressure gas cylinder 2. The inlet of the second throttle orifice 11 is connected to the outlet of the second high-pressure isolation self-locking valve 9. The outlet of the second throttle orifice 11 is connected to the inlet of the second pressure reducer 13. The outlet of the second pressure reducer 13 is connected to the inlet of the second pressure control solenoid valve 15. The outlet of the second pressure control solenoid valve 15 is connected to the inlet of the second buffer gas cylinder 19 and the second low-pressure pressure sensor 17. The outlet of the second buffer gas cylinder 19 is connected to the inlet of the second cold air thruster 23 of each branch.

[0025] A high-pressure through-lock valve 3 has one end port connected to the outlet of the first high-pressure gas cylinder 1 in the first branch, and the other end port connected to the outlet of the second high-pressure gas cylinder 2 in the second branch. A low-pressure through-lock valve 20 has one end port connected to the outlet of the first buffer gas cylinder 18 in the first branch, and the other end port connected to the outlet of the second buffer gas cylinder 19 in the second branch.

[0026] The first high-pressure sensor 6, the second high-pressure sensor 7, the first high-pressure isolation self-locking valve 8, the second high-pressure isolation self-locking valve 9, the first pressure control solenoid valve 14, the second pressure control solenoid valve 15, the first low-pressure sensor 16, the second low-pressure sensor 17, the high-pressure through self-locking valve 3, the low-pressure through self-locking valve 20, the first cold air thruster 22, and the second cold air thruster 23 are connected to the control unit 21 via cables.

[0027] The first pressure reducer 12 and the second pressure reducer 13 are mechanical pressure reducers. The dual branches use a first-level mechanical pressure reduction and a second-level electronic pressure reduction mode to achieve system pressure regulation (the first branch uses the first pressure reducer 12 in conjunction with the first pressure control solenoid valve 14 to reduce pressure, and the second branch uses the second pressure reducer 13 in conjunction with the second pressure control solenoid valve 15 to reduce pressure).

[0028] The inlets of the first pressure reducer 12 and the second pressure reducer 13 are respectively connected to the first throttling orifice 10 and the second throttling orifice 11, so as to reduce the impact of high pressure gas on the pressure reducer through the throttling orifice.

[0029] Preferably, the connections between the components in the first branch, the components in the second branch, the high-pressure through-locking valve and the two branches, and the low-pressure through-locking valve and the two branches are all achieved through pipelines, and the pipelines are connected by welding or by a metal ball head-metal conical surface screw connection hard seal method.

[0030] In this invention, the propulsion system has a first branch and a second branch that back each other up. In the event of a single branch failure, the other branch performs basic functions. In the event of a single branch failure only in the pressure reduction stage, i.e., a failure of the pressure reducer or the pressure control solenoid valve, the control unit opens the high-pressure through-lock valve and the low-pressure through-lock valve to enable simultaneous consumption of gas from both gas cylinders and pairing of the two cold gas thrusters under failure conditions, thus ensuring thrust supply under the normal center of gravity adjustment function of the system.

[0031] Working principle: During ground refueling, high-pressure gas is injected into the high-pressure gas cylinder through the gas filling and emptying valves of the two branches; During on-orbit operation, the control unit drives the high-pressure isolation self-locking valve to open, allowing the high-pressure gas in the high-pressure cylinder to be reduced to the target pressure via a pressure reducer, i.e., the first-stage mechanical pressure reduction. The control unit controls the pressure control solenoid valve to fill the buffer cylinder with gas. The low-pressure sensor monitors the gas pressure in the buffer cylinder in real time and feeds the test data back to the control unit. When the pressure in the buffer cylinder is lower than the lower limit of the target pressure, the control unit drives the pressure control solenoid valve to open with a set pulse width to replenish gas. When the pressure in the buffer cylinder is higher than the upper limit of the target pressure, the pressure control solenoid valve remains closed, thereby controlling the pressure in the buffer cylinder to remain stable within the target low-pressure range, i.e., the second-stage electronic pressure reduction. The control unit controls the cold gas thruster to operate, and the gas in the buffer cylinder is ejected from the cold gas thruster to generate stable thrust, enabling the propulsion system to operate normally. After operating in orbit for a period of time, the remaining amount of high-pressure gas cylinders in the two branches will differ. The difference in the remaining amount of the two high-pressure gas cylinders is monitored by the high-pressure pressure sensors connected to each cylinder and the signals are transmitted to the control unit. When the cumulative error reaches the set threshold, the control unit controls the opening of the high-pressure through-lock valve 3 to balance the two high-pressure gas cylinders and maintain the stability of the overall center of mass.

[0032] Example 1: like Figure 1 As shown, during ground refueling of the first branch of the propulsion system of the present invention, high-pressure gas is added to the first high-pressure gas cylinder 1 through the first gas filling and emptying valve 4. During on-orbit operation, the first high-pressure pressure sensor 6 of the branch monitors the pressure of the first high-pressure gas cylinder 1 in real time and transmits the signal to the control unit 21. When operating in orbit, the control unit 21 drives the first high-pressure isolation self-locking valve 8 to open, and the high-pressure gas in the first high-pressure gas cylinder 1 is reduced to the target pressure (first-stage mechanical pressure reduction) by the first pressure reducer 12. The control unit 21 controls the opening and closing of the first pressure control solenoid valve 14 to fill the first buffer gas cylinder 18 with gas, and the first low-pressure sensor 16 monitors the gas in the first buffer gas cylinder 18 in real time. The pressure is measured and the test data is fed back to the control unit 21. When the pressure in the first buffer gas cylinder 18 is lower than the target lower pressure limit, the control unit 21 drives the first pressure control solenoid valve 14 to open and replenish gas with a set pulse width. When the pressure in the first buffer gas cylinder 18 is higher than the target upper pressure limit, the first pressure control solenoid valve 14 is kept closed. In this way, the pressure in the first buffer gas cylinder 18 is controlled to be stable in the target low pressure range (two-stage electronic pressure reduction). The control unit 21 controls the first cold gas thruster 22 to work. The gas in the first buffer gas cylinder 18 is ejected from the first cold gas thruster 22 to generate stable thrust, so as to realize the normal operation of the first branch of the system.

[0033] When the second branch of the propulsion system is refueled on the ground, high-pressure gas is added to the second high-pressure gas cylinder 2 through the second gas filling and emptying valve 5. During on-orbit operation, the second high-pressure pressure sensor 7 of the branch monitors the pressure of the second high-pressure gas cylinder 2 in real time and transmits the signal to the control unit 21. When operating in orbit, the control unit 21 drives the second high-pressure isolation self-locking valve 9 to open, and the high-pressure gas in the second high-pressure gas cylinder 2 is reduced to the target pressure (first-stage mechanical pressure reduction) by the second pressure reducer 13. The control unit 21 controls the second pressure control solenoid valve 15 to open and close, filling the second buffer gas cylinder 19 with gas. The second low-pressure sensor 17 monitors the gas pressure in the second buffer gas cylinder 19 in real time. The test data is fed back to the control unit 21. When the pressure in the second buffer gas cylinder 19 is lower than the target lower pressure limit, the control unit 21 drives the second pressure control solenoid valve 15 to open and replenish gas with a set pulse width. When the pressure in the second buffer gas cylinder 19 is higher than the target upper pressure limit, the second pressure control solenoid valve 15 is kept closed. In this way, the pressure in the second buffer gas cylinder 19 is controlled to be stable in the target low pressure range (two-stage electronic pressure reduction). The control unit 21 controls the second cold gas thruster 23 to work. The gas in the second buffer gas cylinder 19 is ejected from the second cold gas thruster 23 to generate stable thrust, so as to realize the normal operation of the second branch of the system.

[0034] The propulsion system adopts a dual-branch parallel design, with the two branches backing each other up. In the event of a single-branch failure, the other branch can still perform basic functions. In the event of a single-branch failure only in the pressure reduction stage, i.e., a failure of the pressure reducer or pressure control solenoid valve, the high-pressure through-lock valve 3 and the low-pressure through-lock valve 20 can be opened by the control unit 21. This also enables the simultaneous consumption of gas from both branch cylinders and the paired operation of the dual-branch cold gas thrusters under fault conditions, ensuring the thrust supply under the normal center of gravity adjustment function of the system.

[0035] Example 2: Using the aforementioned cold air propulsion system to achieve center of gravity adjustment involves three steps: The first step is to adjust the flow rate by controlling the pre-spray pressure, thereby adjusting the centroid. The second step is to adjust the center of gravity by controlling the propellant consumption through thruster pairing. The third step is to adjust the center of gravity by controlling the self-locking valve through the control unit to balance and adjust the remaining amount of high-pressure gas cylinder.

[0036] Specifically, The first step of the center of gravity adjustment function is: The centroid is adjusted by controlling the pre-jet pressure to regulate the flow rate: During on-orbit operation, based on the difference in average specific impulse performance between the two branches of the cold gas thruster, a matching buffer cylinder pressure, i.e., the pre-jet pressure of the cold gas thruster, is set to minimize the difference in outlet flow rate between the two branches. The calculation formula for setting the buffer cylinder pressure is as follows:

[0037] Among them, (LP) i , Isp i T i F i Let i represent the pressure of the buffer cylinder in the i-th branch, the outlet mass flow rate, the average specific impulse, the pressure of the buffer cylinder, and the average thrust, respectively, i=1,2; R Let A be the ideal gas constant, γ be the adiabatic index of the gas, and A be the adiabatic index of the gas. t The cross-sectional area of ​​the thruster throat; the pressure of the buffer cylinder is reset by controlling the opening and closing of the solenoid valve through the control unit.

[0038] The second step of the center of mass adjustment function is: Propellant consumption is controlled by thruster pairing: During system design and integration, thrusters with thrust deviations within ±5% are selected for pairing and installation. That is, thruster Aj of the first cold gas thruster 22 of the first branch is paired and installed with thruster Bj of the second cold gas thruster 23 of the second branch, and the thrust deviation between the two thrusters is controlled within ±5% (j=1,2,…,n). During on-orbit operation, the paired thrusters work simultaneously, that is, thruster Aj of the first cold gas thruster 22 of the first branch and thruster Bj of the second cold gas thruster 23 of the second branch work simultaneously (j=1,2,…,n). This method controls the balanced consumption of propellant in the two branches of the cold gas propulsion system, achieving the function of center of mass control.

[0039] The third step of the center of mass adjustment function is: Balance the remaining amount by using a self-locking valve: After operating in orbit for a period of time, due to the accumulation of system errors, a difference in the remaining amount in the first high-pressure gas cylinder 1 and the second high-pressure gas cylinder 2 of the dual-branch system will occur. The difference in the remaining amount in the first high-pressure gas cylinder 1 and the second high-pressure gas cylinder 2 can be monitored by the first high-pressure pressure sensor 6 and the second high-pressure pressure sensor 7. When the accumulated error reaches the set threshold, the control unit 21 controls the opening of the high-pressure through-locking valve 3 to balance the two gas cylinders and maintain the stability of the overall center of mass. The difference in the remaining amount in the gas cylinders can be calculated by the following formula:

[0040] Where Δm is the difference in the remaining amount in the two high-pressure gas cylinders, M is the molar mass of the gas, R is the ideal gas constant, (HP)1, V1, and T1 are the pressure, volume, and temperature of the first high-pressure gas cylinder, respectively, and (HP)2, V2, and T2 are the pressure, volume, and temperature of the second high-pressure gas cylinder, respectively.

[0041] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A highly stable cold gas propulsion system with adjustable center of mass, used for attitude and orbit control of a satellite during its on-orbit operation, characterized in that: The system adopts a dual-branch parallel design, and the two branches work simultaneously during the on-orbit period. The system includes a first branch, a second branch, a high-pressure through-lock valve (3), a low-pressure through-lock valve (20), and a control unit. The first and second branches have the same composition, both including a high-pressure gas cylinder, a gas filling and emptying valve, a high-pressure pressure sensor, a high-pressure isolation self-locking valve, a throttle orifice, a pressure reducer, a pressure control solenoid valve, a buffer gas cylinder, a low-pressure pressure sensor, and a cold gas thruster; the upstream and downstream of the two branches are connected by a high-pressure through self-locking valve (3) and a low-pressure through self-locking valve (20), respectively; the high-pressure pressure sensor, the high-pressure isolation self-locking valve, the pressure control solenoid valve, the low-pressure pressure sensor, the cold gas thruster, the high-pressure through self-locking valve (3), and the low-pressure through self-locking valve (20) are connected to the control unit by cables; During ground refueling, high-pressure gas is injected into the high-pressure gas cylinder through the gas filling and emptying valves of the two branches; During on-orbit operation, the control unit drives the high-pressure isolation self-locking valve to open, allowing the high-pressure gas in the high-pressure cylinder to be reduced to the target pressure via a pressure reducer, i.e., the first-stage mechanical pressure reduction. The control unit controls the pressure control solenoid valve to fill the buffer cylinder with gas. The low-pressure sensor monitors the gas pressure in the buffer cylinder in real time and feeds the test data back to the control unit. When the pressure in the buffer cylinder is lower than the lower limit of the target pressure, the control unit drives the pressure control solenoid valve to open with a set pulse width to replenish gas. When the pressure in the buffer cylinder is higher than the upper limit of the target pressure, the pressure control solenoid valve remains closed, thereby controlling the pressure in the buffer cylinder to remain stable within the target low-pressure range, i.e., the second-stage electronic pressure reduction. The control unit controls the cold gas thruster to operate, and the gas in the buffer cylinder is ejected from the cold gas thruster to generate stable thrust, enabling the propulsion system to operate normally. In both the first and second branches, a throttling orifice is provided upstream of the pressure reducer to reduce the impact of high-pressure gas on the pressure reducer. After working in orbit for a period of time, the remaining amount in the high-pressure gas cylinders in the two branches will differ; the difference in the remaining amount in the two high-pressure gas cylinders will be monitored by the high-pressure pressure sensors connected to each cylinder and the signal will be transmitted to the control unit. When the cumulative error reaches the set threshold, the control unit will control the opening of the high-pressure through-lock valve (3) to balance the two high-pressure gas cylinders and maintain the stability of the overall center of mass.

2. The highly stable cold gas propulsion system with adjustable center of mass according to claim 1, characterized in that: In the first branch, the throttling orifice set upstream of the pressure reducer is defined as the first throttling orifice (10). The outlet of the first gas filling and exhaust valve (4), the inlet of the first high pressure pressure sensor (6) and the inlet of the first high pressure isolation self-locking valve (8) are all connected to the outlet of the first high pressure gas cylinder (1). The inlet of the first throttle orifice (10) is connected to the outlet of the first high pressure isolation self-locking valve (8). The outlet of the first throttle orifice (10) is connected to the inlet of the first pressure reducer (12). The outlet of the first pressure reducer (12) is connected to the inlet of the first pressure control solenoid valve (14). The outlet of the first pressure control solenoid valve (14) is connected to the inlet of the first buffer gas cylinder (18) and the first low pressure pressure sensor (16). The outlet of the first buffer gas cylinder (18) is connected to the inlet of the first cold air thruster (22) of each branch.

3. A highly stable cold gas propulsion system with adjustable center of mass according to claim 2, characterized in that: In the second branch, the throttling orifice set upstream of the pressure reducer is defined as the second throttling orifice (11). The outlet of the second gas supply valve (5), the inlet of the second high-pressure pressure sensor (7) and the inlet of the second high-pressure isolation self-locking valve (9) are all connected to the outlet of the second high-pressure gas cylinder (2). The inlet of the second throttle orifice (11) is connected to the outlet of the second high-pressure isolation self-locking valve (9). The outlet of the second throttle orifice (11) is connected to the inlet of the second pressure reducer (13). The outlet of the second pressure reducer (13) is connected to the inlet of the second pressure control solenoid valve (15). The outlet of the second pressure control solenoid valve (15) is connected to the inlet of the second buffer gas cylinder (19) and the second low-pressure pressure sensor (17). The outlet of the second buffer gas cylinder (19) is connected to the inlet of each of the second branch's second cold air thrusters (23).

4. A highly stable cold gas propulsion system with adjustable center of mass according to claim 3, characterized in that: Both branches use mechanical pressure regulators; both branches employ a primary mechanical pressure reduction followed by a secondary electronic pressure reduction mode to regulate system pressure, specifically: In the first branch, the first pressure reducer (12) and the first pressure control solenoid valve (14) work together to reduce pressure; In the second branch, the second pressure reducer (13) and the second pressure control solenoid valve (15) work together to reduce pressure.

5. A highly stable cold gas propulsion system with adjustable center of mass according to claim 3, characterized in that: The connections between the components in the first branch, the components in the second branch, the high-pressure through-locking valve and the two branches, and the low-pressure through-locking valve and the two branches are all achieved through pipelines. The pipelines are connected by welding or by a metal ball head-metal conical surface screw connection hard seal.

6. A highly stable cold gas propulsion system with adjustable center of mass according to claim 3, characterized in that: In the propulsion system, the first branch and the second branch back each other up. In the event of a single branch failure, the other branch performs basic functions. In the event of a single branch failure only in the pressure reduction stage, i.e., a failure of the pressure reducer or the pressure control solenoid valve, the control unit opens the high-pressure through-lock valve and the low-pressure through-lock valve to enable simultaneous consumption of gas from both branch cylinders and pairing of the two branch cold gas thrusters under the failure condition, thus ensuring the thrust supply under the normal center of gravity adjustment function of the system.

7. A highly stable cold gas propulsion system with adjustable center of mass according to claim 1, characterized in that: One end of the high-pressure through-lock valve (3) is connected to the outlet of the first high-pressure gas cylinder (1) of the first branch, and the other end of the high-pressure through-lock valve (3) is connected to the outlet of the second high-pressure gas cylinder (2) of the second branch; one end of the low-pressure through-lock valve (20) is connected to the outlet of the first buffer gas cylinder (18) of the first branch, and the other end of the low-pressure through-lock valve (20) is connected to the outlet of the second buffer gas cylinder (19) of the second branch.

8. A method for center-of-mass adjustment based on the highly stable cold gas propulsion system with adjustable center of mass as described in claim 3, characterized in that... include: The first step is to adjust the flow rate by controlling the pre-spray pressure, thereby adjusting the centroid. The second step is to adjust the center of gravity by controlling the propellant consumption through thruster pairing. The third step is to adjust the center of gravity by controlling the self-locking valve through the control unit to balance and adjust the remaining amount of high-pressure gas cylinder.

9. The centroid adjustment method according to claim 8, characterized in that: The method of adjusting the centroid by controlling the pre-spray pressure and adjusting the flow rate is as follows: During on-orbit operation, based on the difference in average specific impulse performance between the two branches of the cold gas thruster, a matching buffer cylinder pressure, i.e., the pre-jet pressure of the cold gas thruster, is set to minimize the difference in outlet flow rate between the two branches. The calculation formula for setting the buffer cylinder pressure is as follows: Among them, (LP) i , Isp i T i F i Let i represent the pressure of the buffer cylinder in the i-th branch, the outlet mass flow rate, the average specific impulse, the pressure of the buffer cylinder, and the average thrust, respectively, i=1,2; R Let A be the ideal gas constant, γ be the adiabatic index of the gas, and A be the adiabatic index of the gas. t The cross-sectional area of ​​the thruster throat; the pressure of the buffer cylinder is reset by controlling the opening and closing of the solenoid valve through the control unit.

10. The centroid adjustment method according to claim 8, characterized in that: The method of adjusting the center of mass by controlling propellant consumption through thruster pairing is specifically as follows: Propellant consumption is controlled by pairing cold gas thrusters: During system design and integration, cold gas thrusters with thrust deviation within ±5% are selected for pairing and installation, that is, the cold gas thruster Aj of the first branch is paired and installed with the cold gas thruster Bj of the second branch, and the thrust deviation between the two cold gas thrusters is controlled within ±5%, j=1,2,…,n; During on-orbit operation, the paired cold gas thrusters work simultaneously, that is, the first branch cold gas thruster Aj and the second branch cold gas thruster Bj work at the same time; in this way, the propellant consumption of the two branches of the cold gas propulsion system is balanced, thereby achieving the function of center of mass control.

11. The centroid adjustment method according to claim 8, characterized in that: The method of adjusting the center of gravity by controlling the self-locking valve through the control unit to balance and adjust the remaining amount of high-pressure gas cylinder is as follows: After operating in orbit for a period of time, due to the accumulation of system errors, the remaining amount in the dual-branch high-pressure cylinders will differ. The difference in the remaining amount in the two branch high-pressure cylinders is monitored by the high-pressure sensors connected to each branch and the signals are transmitted to the control unit. When the cumulative error reaches the set threshold, the control unit controls the opening of the high-pressure through-lock valve to balance the two high-pressure gas cylinders and maintain the stability of the overall center of mass.

12. The centroid adjustment method according to claim 11, characterized in that: The difference in the remaining amount in the two high-pressure gas cylinders is calculated using the following formula: Where Δm is the difference in the remaining amount in the two high-pressure gas cylinders, M is the molar mass of the gas, R is the ideal gas constant, (HP)1, V1, and T1 are the pressure, volume, and temperature of the first high-pressure gas cylinder, respectively, and (HP)2, V2, and T2 are the pressure, volume, and temperature of the second high-pressure gas cylinder, respectively.

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