An aircraft fuel servo valve high temperature test system

Abstract

The application discloses an aircraft fuel servo valve high-temperature test system and relates to the field of test systems.The system comprises a normal-temperature oil supply module, a high-pressure pump, a main heating and heat exchange module, a controller and an oil return shunt module.The normal-temperature oil supply module comprises an oil tank and a low-pressure booster pump, and the high-pressure pump is used for outputting high-pressure and high-temperature fuel;the main heating and heat exchange module is arranged between the high-pressure pump outlet and the fluid inlet of the measured valve and is used for heating the fuel to a preset test temperature;the oil return shunt module inlet is communicated with the oil return port of the measured valve, the first outlet is communicated with the high-pressure pump inlet, and the second outlet is communicated with the oil tank.The controller is connected with the main heating and heat exchange module and the oil return shunt module, is used for collecting two temperature signals, adjusting the heating power and the two outlet flow distribution, and maintaining the oil temperature after the high-temperature oil return and the normal-temperature fuel are mixed within the safety threshold of the high-pressure pump.The application solves the problem that the test system cannot continuously and stably operate due to the fact that the high-pressure pump cannot long-term bear extremely high-temperature fluid.

Description

Technical Field

[0001] This invention relates to the field of testing systems, and more particularly to a high-temperature testing system for aircraft fuel servo valves. Background Technology

[0002] As a core control component of the aircraft engine fuel system, the performance of the fuel servo valve directly affects flight safety. Because fuel servo valves face extremely complex and harsh operating conditions during actual flight, such as high ambient temperatures and high-temperature media, a dedicated testing system is required during product development and maintenance to simulate extreme real-world high-temperature and high-pressure fluid environments on the ground. This allows for long-term durability assessment and calibration testing of its various dynamic and static performance characteristics.

[0003] In current technologies, to ensure the fuel entering the tested fuel servo valve meets the specified high-temperature test standards, conventional testing systems typically employ a method of overall heating of the system's fluid medium. Specifically, these technologies usually involve installing a high-power heating device in the system's main fuel tank or at the tank outlet to uniformly heat all the test fuel stored in the tank to the target high temperature. Subsequently, a high-pressure hydraulic pump is used to directly extract and pressurize the high-temperature fuel from the tank before delivering it to the tested fuel servo valve. After testing, the fuel flows back to the high-temperature tank via the return line, forming an overall high-temperature fluid circulation.

[0004] However, limited by current mechanical manufacturing capabilities and the physical limitations of sealing materials, the high-pressure hydraulic pumps (such as high-pressure plunger pumps) responsible for providing fluid power in the testing system cannot withstand extreme high temperatures of the medium for extended periods. For example, testing requirements often reach 150°C to 200°C, while the maximum withstand temperature of conventional high-pressure pumps is typically difficult to exceed 120°C. When existing testing systems directly pump fuel at extremely high temperatures, the high-temperature, high-pressure fluid medium directly penetrates and acts on the internal mechanical components and seals of the high-pressure pump, easily leading to severe thermal deformation of the pump body, increased internal leakage, rupture of the lubricating oil film, and even rotor seizure and burnout. This prevents the entire testing system from operating stably and continuously under high-temperature conditions for extended periods, limiting the successful implementation of long-cycle high-temperature testing tasks for aircraft fuel servo valves. Summary of the Invention

[0005] To address the aforementioned technical problems and deficiencies, the purpose of this invention is to provide a high-temperature testing system for aircraft fuel servo valves, which can solve the problem in related technologies where high-pressure pumps cannot withstand extremely high-temperature fluids for extended periods, resulting in the inability of the testing system to operate continuously and stably.

[0006] To achieve the above objectives, the present invention provides a high-temperature testing system for aircraft fuel servo valves, comprising:

[0007] The ambient temperature fuel supply module includes a fuel tank and a low-pressure booster pump connected by sequential pipelines.

[0008] High-pressure pump, used to output high-pressure, sub-high-temperature fuel;

[0009] The main heating heat exchange module is located between the outlet of the high-pressure pump and the fluid inlet of the fuel servo valve of the aircraft under test. It is used to heat the high-pressure sub-high temperature fuel to the preset test temperature and output the high-pressure high temperature fuel to the fuel servo valve of the aircraft under test.

[0010] The controller is connected to the main heating heat exchange module and the oil return diversion module respectively;

[0011] The controller is used to acquire the fuel temperature feedback signal at the fluid inlet and the fuel temperature monitoring signal at the inlet of the high-pressure pump. Based on the fuel temperature feedback signal and the fuel temperature monitoring signal, it adjusts the heating power of the main heating heat exchange module and the flow distribution ratio between the first outlet and the second outlet so that the fuel temperature entering the fuel servo valve of the aircraft under test reaches the preset test temperature. It also maintains the temperature of the mixed fuel generated after the high-temperature return oil circulating through the first outlet to the inlet of the high-pressure pump mixes with the room-temperature fuel provided by the low-pressure booster pump within the safe operating temperature threshold of the high-pressure pump.

[0012] This invention employs the aforementioned high-temperature testing system for aircraft fuel servo valves. By placing the main heating heat exchange module between the outlet of the high-pressure pump and the fluid inlet, it changes the traditional mode of heating the entire fuel tank. This allows the high-pressure pump to only pump sub-high-temperature fuel, avoiding the physical temperature resistance limits of the pump's mechanical components and reducing the risk of thermal deformation and lubrication failure. Simultaneously, this invention introduces a return oil diversion closed-loop control architecture. The controller monitors the fuel temperature at the high-pressure pump inlet and the fluid inlet in real time, synchronously adjusting the heating power of the main heating heat exchange module and the mixing ratio of high-temperature return oil and low-pressure ambient-temperature fuel. This design not only limits the fluid temperature at the high-pressure pump inlet to within a safe operating temperature threshold, achieving real-time physical protection for core power components, but also precisely ensures a constant temperature output of the test medium at the servo valve inlet. Furthermore, it significantly reduces the energy consumption of the heating module by recovering and utilizing some of the return oil heat. This invention achieves stable output in a high-pressure, extremely high-temperature test fluid environment while ensuring the long-term safe operation of the fluid power equipment, solving the problem in related technologies where the high-pressure pump cannot withstand extremely high-temperature fluids for extended periods, leading to the inability of the testing system to operate continuously and stably.

[0013] In some embodiments, the system further includes a high-pressure inlet voltage regulating module, which includes:

[0014] The main pressure regulating valve is installed on the pipeline between the outlet of the main heating heat exchange module and the fluid inlet, and is used to regulate the fuel pressure at the fluid inlet;

[0015] A pressure regulating pilot valve, the control port of which is connected to the pilot control terminal of the main pressure regulating valve, is used to provide pilot control pressure to the main pressure regulating valve;

[0016] A local high-pressure cooler is installed between the pilot sampling port of the main pressure regulating valve and the inlet of the pressure regulating pilot valve. It is used to locally cool the high-pressure fuel introduced into the pressure regulating pilot valve so that the temperature of the fuel entering the pressure regulating pilot valve is lower than the temperature limit of the pressure regulating pilot valve.

[0017] By adopting the above technical solution, a local high-pressure cooler is introduced to locally cool a small stream of high-temperature, high-pressure fuel directed to the precision pressure regulating pilot valve. This design avoids the failure of the pilot control components due to overheating of the medium, and significantly improves the accuracy and long-term reliability of pressure control while ensuring that the high-temperature testing environment of the main road is not affected.

[0018] In some embodiments, the high-pressure inlet pressure regulating module further includes a first electro-proportional valve, which is used to receive the control signal from the controller and output proportional regulating air pressure to the pressure regulating pilot valve.

[0019] The high-pressure pump includes a plunger pump driven by a variable frequency drive motor;

[0020] The controller is configured to: acquire the fuel pressure feedback signal at the fluid inlet, calculate the pressure deviation based on the fuel pressure feedback signal, and coordinately adjust the speed of the variable frequency drive motor and the proportional regulating air pressure output by the first electro-proportional valve based on the pressure deviation; wherein, by adjusting the speed of the variable frequency drive motor, the system base flow rate entering the main heating heat exchange module is changed, and by adjusting the proportional regulating air pressure output by the first electro-proportional valve, the overflow opening of the main pressure regulating valve is changed, so as to perform wide-range closed-loop control of the fuel pressure at the fluid inlet.

[0021] By employing the above technical solution, through the coordinated closed-loop control of the variable frequency drive motor and the first electro-proportional valve, the variable frequency speed regulation achieves macroscopic open-source adjustment of the system's basic flow to reduce overflow heat generation, while the first electro-proportional valve achieves microscopic precise adjustment of the pilot pressure. This deep coupling completely eliminates the adjustment dead zone and system oscillation during wide-range pressure control.

[0022] In some embodiments, the main heating heat exchange module includes a spiral wound tube heat exchanger and a hot oil generator unit;

[0023] The tube side of the spiral wound tube heat exchanger is connected between the outlet of the high-pressure pump and the fluid inlet, and the shell side of the spiral wound tube heat exchanger is in closed-loop connection with the hot oil generator unit.

[0024] The oil heater unit is electrically connected to the controller, which is used to adjust the heating power of the main heating heat exchange module by adjusting the heating power of the oil heater unit, forming a closed-loop temperature control circuit to achieve rapid heating of the fuel.

[0025] By employing the above technical solution, a high-power hot oil generator unit is combined with a spiral wound tube heat exchanger to achieve rapid heating of high-pressure, sub-high-temperature fuel oil within a short tube pass. Combined with closed-loop coordinated regulation of the flow distribution ratio, this solution not only boasts extremely high heat exchange efficiency but also ensures both dynamic response speed and high steady-state precision in medium temperature control.

[0026] In some implementations, the return oil diversion module includes a three-way diversion regulating valve;

[0027] The system also includes a return oil back pressure regulating module, located between the return oil port and the three-way diverter regulating valve;

[0028] The return oil back pressure adjustment module includes a back pressure valve and a second electro-proportional valve. The second electro-proportional valve is used to receive the control signal from the controller, adjust and output proportional air pressure to the pilot port of the back pressure valve, so as to adjust the return oil pressure of the fuel servo valve of the aircraft under test in a closed loop.

[0029] By employing the above technical solution, a closed-loop regulation mechanism for return oil back pressure is constructed through a back pressure valve and an electro-proportional valve, which can simulate the real wide-range return oil back pressure conditions of an aircraft engine with extreme stability. Simultaneously, the back pressure control and the downstream three-way flow control are decoupled at the flow path nodes, ensuring that system pressure and temperature regulation do not interfere with each other.

[0030] In some embodiments, an accumulator protection module is connected in parallel on the outlet pipeline of the high-pressure pump; the accumulator protection module includes a high-pressure piston accumulator, a medium-pressure piston accumulator branch and a low-pressure piston accumulator branch.

[0031] The medium-pressure piston accumulator branch includes a medium-pressure piston accumulator, a first ball valve, a second ball valve, and a first pressure switch. The medium-pressure piston accumulator is connected to the outlet pipeline through the first ball valve and to the oil tank through the second ball valve. The first pressure switch is located at the inlet of the medium-pressure piston accumulator.

[0032] The low-pressure piston accumulator branch includes a low-pressure piston accumulator, a third ball valve, and a second pressure switch. The low-pressure piston accumulator is connected to the outlet pipeline through the third ball valve, and the second pressure switch is located at the inlet of the low-pressure piston accumulator.

[0033] The controller is electrically connected to the first pressure switch, the second pressure switch, the first ball valve, the second ball valve, and the third ball valve, respectively.

[0034] When the oil supply pressure reaches the set protection threshold of the medium-pressure piston accumulator, the controller controls the first ball valve to close and the second ball valve to open, so that the medium-pressure piston accumulator is disconnected from the high-pressure oil supply circuit and released pressure; when the oil supply pressure reaches the set protection threshold of the low-pressure piston accumulator, the controller controls the third ball valve to close, so that the low-pressure piston accumulator is disconnected from the high-pressure oil supply circuit and released pressure.

[0035] By adopting the above technical solution, a multi-stage parallel accumulator protection module is set up, which can effectively suppress fluid pulsation in different test pressure ranges. Through the intelligent cut-off and pressure relief logic of pressure switches and ball valves, the damage of certain accumulators due to excessive compression in the high-pressure section is reduced, and the service life of buffer components is extended.

[0036] In some implementations, a wide-range flow measurement module is provided between the main heating heat exchange module and the fuel servo valve of the aircraft under test.

[0037] The wide-range flow measurement module includes a main pipeline and a small-range measurement branch and a bypass branch connected in parallel on the main pipeline; a first flow meter is connected in series on the main pipeline, a second flow meter is connected in series on the small-range measurement branch, and a high-temperature ball valve is installed on the bypass branch; the range of the first flow meter is greater than the range of the second flow meter.

[0038] When the test flow rate is in the low flow range, the controller closes the high-temperature ball valve on the bypass branch to force all the fuel to flow through the small-range measurement branch and collects the output of the second flow meter as the flow measurement signal.

[0039] Using the above technical solution, a wide-range flow measurement module composed of parallel flow meters of varying sizes was designed. Through intelligent logic switching of the controller, sufficient flow capacity is ensured during dynamic characteristic testing of large flow rates, while also meeting the extremely high resolution requirements for static measurement of minute leakage in the valve body, overcoming the limitation of single-instrument range.

[0040] In some implementations, the system also includes an online particle size analyzer for detecting the cleanliness of the supply and return oil media;

[0041] The sampling inlet of the online particle size analyzer is connected to the fuel supply line and the fuel return line respectively through a high-pressure resistant needle valve. The high-pressure resistant needle valve is configured to open during sampling and measurement to throttle and regulate the fuel flow into the online particle size analyzer, and to close during non-measurement to isolate the physical impact of high-temperature and high-pressure fuel on the online particle size analyzer.

[0042] By employing the above technical solution, and utilizing the dual effects of the high-pressure needle valve—interception, isolation, and throttling—a safe sampling and testing branch is established alongside the main flow path under extreme high temperature and pressure. This solves the compatibility problem of precision optical detectors being unable to withstand high-pressure and high-temperature impacts, and enables real-time online monitoring of the contamination level of the working medium in the fuel system.

[0043] In some implementations, the system also includes a tank cooling circulation filter module that is independent of the main test loop;

[0044] The oil tank cooling circulation filtration module includes a cooling circulation pump, a circulation pipeline filter, and two-stage plate water-cooled heat exchangers connected in series.

[0045] The cooling circulation pump is used to draw fuel from the tank, and the fuel is filtered through the circulation pipeline filter and cooled by the two-stage series plate water-cooled heat exchanger before flowing back to the tank, so that the fuel in the tank is always kept within the set temperature range.

[0046] By adopting the above technical solution, an independent oil tank cooling circulation filtration module was added outside the main test circuit. This module acts like an independent dialysis system, continuously filtering out impurities in the oil tank and performing two-stage deep cooling, completely eliminating heat accumulation and particulate matter contamination generated during long-term operation, and providing the high-pressure pump with an absolutely pure room-temperature base oil source.

[0047] In some implementations, the system also includes a high-temperature environment chamber for providing a simulated high-temperature environment for the fuel servo valve of the aircraft under test.

[0048] The aircraft fuel servo valve under test is installed inside the high-temperature environment chamber; the high-temperature environment chamber has a nitrogen-filled, balanced, pressure-regulating, and explosion-proof system.

[0049] The high-temperature environment chamber is equipped with a heat transfer oil heat exchanger, which heats and circulates the air inside the chamber through high-temperature heat transfer oil introduced from the outside. The bottom of the high-temperature environment chamber is equipped with an inclined oil receiving tray and an oil drain valve that connects to a closed waste oil tank outside the chamber.

[0050] The above technical solution is adopted, and a high-temperature environmental chamber equipped with a nitrogen-filled explosion-proof and pressure balancing system is used. Indirect convection heating with heat transfer oil is employed to realistically simulate extreme external high-temperature environments. Through rigorous nitrogen inerting and waste oil drainage design, the risk of explosion caused by aviation kerosene volatilization is completely isolated from the physical level, ensuring safety. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the overall architecture of a high-temperature testing system for an aircraft fuel servo valve according to an embodiment of the present invention.

[0052] Figure 2This is a partial schematic diagram of a high-voltage inlet voltage regulating module according to an embodiment of the present invention;

[0053] Figure 3 This is a partial schematic diagram of a main heating heat exchange module according to an embodiment of the present invention;

[0054] Figure 4 This is a partial schematic diagram of a system regarding a return oil back pressure adjustment module according to an embodiment of the present invention;

[0055] Figure 5 This is a partial schematic diagram of a system for an energy storage protection module according to an embodiment of the present invention;

[0056] Figure 6 This is a partial schematic diagram of a wide-range flow measurement module according to an embodiment of the present invention. Detailed Implementation

[0057] The terminology used in the following embodiments of the present invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and appended claims of the present invention, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in the present invention refers to any or all possible combinations comprising one or more of the listed items.

[0058] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of the present invention, unless otherwise stated, "a plurality of" means two or more.

[0059] The technical solution of the present invention will be further described in detail below with reference to embodiments. The embodiments of the present invention provide a high-temperature testing system for aircraft fuel servo valves, which can be used for testing during the development and maintenance of fuel servo valves in the aviation field. It can simulate extremely complex and harsh working environments, solving the technical problem that existing testing systems are limited by the operating temperatures of components such as pumps and regulating valves, and therefore cannot operate stably for extended periods at high temperatures.

[0060] This embodiment provides a high-temperature testing system for aircraft fuel servo valves (hereinafter referred to as the system), such as Figure 1 As shown, it includes a normal temperature oil supply module, a high-pressure pump 13, a main heating heat exchange module 2, a controller 3, and a return oil diversion module 4.

[0061] The ambient temperature oil supply module serves as the basic fluid power source of the system, including an oil tank 11 and a low-pressure booster pump 12 connected in sequence by pipelines.

[0062] The fuel tank 11 is used to store aviation kerosene as the working medium. In some embodiments, it can be a 304 stainless steel fuel tank with a total volume of 160L and an effective volume of 128L. The operating temperature range of the fuel tank 11 covers room temperature to 80°C. The fuel tank 11 is equipped with a baffle plate to prevent the spread of contaminants. The return and outlet areas of the fuel tank 11 are physically isolated to prevent air bubbles from entering the outlet pipe of the fuel tank 11.

[0063] The low-pressure booster pump 12 can be an electric centrifugal pump with a rated power of 0.55kW, a rated flow rate of 5m³ / h, and a head of 24m. It is used to draw room temperature aviation kerosene from the oil tank 11 and provide an initial low-pressure room temperature fuel supply to the downstream high-pressure pump 13, thus preventing the high-pressure pump 13 from sucking in cavitation.

[0064] The high-pressure pump 13 is connected to the low-pressure booster pump 12. The high-pressure pump 13 can be an axial piston pump with a displacement of 40 mL / r, driven by a variable frequency drive motor with a rated power of 22 kW, for outputting high-pressure sub-high-temperature fuel. The temperature of the high-pressure sub-high-temperature fuel is below 120°C, specifically in the range of 90-120°C.

[0065] The main heating heat exchange module 2 is located between the outlet of the high-pressure pump 13 and the fluid inlet of the fuel servo valve V of the aircraft under test. Its function is to heat the high-pressure sub-high temperature fuel output by the high-pressure pump 13 to a preset test temperature, such as heating aviation kerosene to above 150°C, so as to output high-pressure high-temperature fuel to the fuel servo valve V of the aircraft under test.

[0066] The controller 3 can be an industrial control computer or a programmable logic controller, which is electrically connected to the oil return diversion module 4 and the main heating heat exchange module 2, and is responsible for coordinating the signal acquisition and action execution of the entire system.

[0067] The inlet of the return oil diversion module 4 is connected to the return oil port of the fuel servo valve V of the aircraft under test. The first outlet 401 of the return oil diversion module 4 is connected to the inlet of the high-pressure pump 13, and the second outlet 402 of the return oil diversion module 4 is connected to the fuel tank 11.

[0068] Controller 3 is used to obtain the fluid inlet (corresponding to) of the fuel servo valve V of the aircraft under test. Figure 1 The temperature detection point T1 in the middle is the fuel temperature feedback signal collected by the temperature sensor, and the fuel temperature is obtained from the inlet of the high-pressure pump 13 (corresponding to...). Figure 1 The temperature detection point T2 in the middle is a fuel temperature monitoring signal collected by another temperature sensor.

[0069] Since conventional high-pressure pump 13 cannot withstand high-temperature media exceeding 120°C for extended periods, directly inputting all the high-temperature return oil from the fuel servo valve V of the aircraft under test into high-pressure pump 13 would cause the internal seals of high-pressure pump 13 to fail and the rotor to seize and burn out. Therefore, controller 3 synchronously adjusts the heating power of main heating heat exchange module 2 and dynamically adjusts the flow distribution ratio between the first outlet 401 and the second outlet 402 of return oil diversion module 4 based on the fuel temperature feedback signal at the fluid inlet and the fuel temperature monitoring signal at the inlet of high-pressure pump 13. This ensures that the fuel temperature entering the fuel servo valve V of the aircraft under test reaches the preset test temperature, while maintaining the temperature of the mixed fuel generated after the high-temperature return oil circulating to the inlet of high-pressure pump 13 via the first outlet 401 mixes with the room-temperature fuel provided by low-pressure booster pump 12 within the safe operating temperature threshold of high-pressure pump 13.

[0070] Specifically, the return oil diversion module 4 directly circulates a portion of the high-temperature return oil through the first outlet 401 to the inlet of the high-pressure pump 13, while the other portion of the high-temperature return oil is discharged back to the fuel tank 11 through the second outlet 402. The high-temperature return oil that circulates to the inlet of the high-pressure pump 13 through the first outlet 401 physically mixes with the ambient temperature fuel continuously supplied by the low-pressure booster pump 12 at the inlet of the high-pressure pump 13 (temperature detection point T2) to generate a mixed fuel at a sub-high temperature (below 120°C).

[0071] Furthermore, considering that under a wide range of dynamic testing conditions (especially when simulating extremely low or extremely high return oil back pressure), the fluid pressure at the first outlet 401 of the return oil diversion module may have a significant pressure difference with the oil supply pressure provided by the low-pressure booster pump 12, a check valve is installed in series on both the outlet pipe of the low-pressure booster pump 12 and the pipe of the first outlet 401 to prevent backflow between the two fluids due to excessive pressure difference. After passing through their respective check valves, the two fuel flows converge into the mixing buffer pipe or mixing chamber located at the inlet of the high-pressure pump 13 for physical mixing, and are then drawn into the high-pressure pump 13. Through the physical one-way isolation of the check valves and the setting of the buffer mixing space, the risk of crossflow when different pressure oil sources converge is eliminated, ensuring the safe implementation of closed-loop regulation of fluid flow distribution.

[0072] The controller 3 precisely controls the mixing ratio of high-temperature return oil, ensuring that the temperature of the mixed fuel is always maintained within the safe operating temperature threshold of the high-pressure pump 13, which is 120°C. This ingenious structure introduces room-temperature cold oil into the closed-loop cycle for neutralization, which not only retains most of the heat to reduce the energy consumption of the main heating heat exchange module 2, but also fundamentally ensures the long-term stable operation of the high-pressure pump 13 under high-temperature test conditions.

[0073] The specific workflow of the high-temperature testing system for the aircraft fuel servo valve in this embodiment is as follows:

[0074] At the start of the test, the low-pressure booster pump 12 draws room-temperature fuel from the fuel tank 11 and pumps it to the inlet of the high-pressure pump 13. The high-pressure pump 13 pressurizes the room-temperature fuel and outputs high-pressure, sub-high-temperature fuel.

[0075] Subsequently, the high-pressure, sub-high-temperature fuel enters the main heating heat exchange module 2, which heats the fuel to a preset test temperature, generating high-pressure, high-temperature fuel. This high-pressure, high-temperature fuel is then fed through the fluid inlet into the fuel servo valve V of the aircraft under test to perform the test operation.

[0076] After the test is completed, the fuel flows out from the return port of the fuel servo valve V of the aircraft under test and enters the inlet of the return fuel diversion module 4.

[0077] Throughout the system's operation, controller 3 continuously acquires the fuel temperature feedback signal at the fluid inlet and the fuel temperature monitoring signal at the inlet of high-pressure pump 13. Based on the fuel temperature feedback signal, controller 3 determines whether the fuel temperature entering the fuel servo valve V of the aircraft under test meets the test standard; and based on the fuel temperature monitoring signal, it determines whether the inlet temperature of high-pressure pump 13 is within a safe range.

[0078] Based on the two temperature signals mentioned above, controller 3 synchronously adjusts the heating power of the main heating heat exchange module 2 to ensure that the fuel temperature entering the fuel servo valve V of the aircraft under test accurately reaches the preset test temperature. At the same time, controller 3 dynamically adjusts the flow distribution ratio between the first outlet 401 and the second outlet 402 of the return oil diversion module 4. A portion of the high-temperature return oil flows out from the first outlet 401 and is directly circulated to the inlet of the high-pressure pump 13; the other portion of the high-temperature return oil flows out from the second outlet 402 and returns to the fuel tank 11.

[0079] The high-temperature return oil circulating from the first outlet 401 to the inlet of the high-pressure pump 13, together with the ambient-temperature fuel continuously supplied by the low-pressure booster pump 12, merges and physically mixes at the inlet of the high-pressure pump 13 to generate mixed fuel.

[0080] The controller 3 precisely controls the circulation flow of the high-temperature return oil, ensuring that the temperature of the mixed fuel is always maintained within the safe operating temperature threshold of the high-pressure pump 13, thereby protecting the high-pressure pump 13 from high-temperature damage while meeting the requirements of high-temperature testing.

[0081] This embodiment solves the technical problem in existing testing systems where high-voltage power components cannot withstand extreme high-temperature fluid media for extended periods, leading to unstable and unsustainable testing.

[0082] This embodiment abandons the traditional working mode of heating the stored fuel as a whole. By placing the main heating heat exchange module 2 between the outlet of the high-pressure pump 13 and the fluid inlet of the fuel servo valve V of the aircraft under test, the main heating heat exchange module 2 rapidly heats the high-pressure sub-high temperature fuel to meet the preset test temperature, thereby removing the high-pressure pump 13 from the high-temperature pumping environment.

[0083] To further address the issues of cooling the high-temperature return fuel discharged from the fuel servo valve V of the tested aircraft and recovering system heat, this embodiment introduces a return fuel diversion module 4. The controller 3 collects real-time fuel temperature feedback signals from the fluid inlet of the fuel servo valve V and fuel temperature monitoring signals from the inlet of the high-pressure pump 13. It then dynamically adjusts the flow distribution ratio between the first outlet 401 and the second outlet 402 of the return fuel diversion module 4, ensuring that an appropriate amount of high-temperature return fuel circulates directly to the inlet of the high-pressure pump 13. This fuel then physically mixes with the ambient-temperature fuel continuously supplied by the low-pressure booster pump 12. The cooling capacity of the ambient-temperature fuel neutralizes the heat from the high-temperature return fuel, thereby maintaining the temperature of the mixed fuel generated and entering the high-pressure pump 13 within the safe operating temperature threshold of the high-pressure pump 13.

[0084] This design breaks the physical constraint between the high temperature of the medium and the temperature resistance limit of the pump body, and achieves low energy consumption and high stability closed-loop high temperature testing while ensuring the long-term stable operation of the core fluid power equipment.

[0085] In some embodiments, such as Figure 2 As shown, the system also includes a high-pressure inlet pressure regulating module 5. The high-pressure inlet pressure regulating module 5 is mainly used to accurately and stably regulate the fuel pressure at the fluid inlet of the fuel servo valve V of the aircraft under test, so that the fuel pressure at the fluid inlet can be continuously and stably adjusted within the range of 0.5MPa to 21MPa.

[0086] The high-pressure inlet pressure regulating module 5 includes a main pressure regulating valve 51, a pressure regulating pilot valve 52, and a local high-pressure cooler 53. In order to overcome the pressure loss along the pipeline caused by the internal pipeline of the main heating heat exchange module 2 and to achieve precise pressure regulation close to the test station, the main pressure regulating valve 51 is set on the pipeline between the outlet of the main heating heat exchange module 2 and the fluid inlet of the fuel servo valve V of the aircraft under test.

[0087] In some embodiments, the main pressure regulating valve 51 can regulate pressure in the range of 0.5MPa to 25MPa, with a rated flow rate of 227L / min, and uses fluororubber as the sealing material internally. The main pressure regulating valve 51 includes a pilot control end and a pilot sampling port, and the valve core opening is determined by the hydraulic pressure at the pilot control end.

[0088] The pressure regulating pilot valve 52 is specifically a pneumatically controlled direct-acting relief valve with a maximum regulating pressure of 25 MPa and a rated flow rate of 10 L / min. The control port of the pressure regulating pilot valve 52 is connected to the pilot control terminal of the main pressure regulating valve 51, and is used to provide pilot control pressure to the main pressure regulating valve 51.

[0089] Since the main pressure regulating valve 51 is located downstream of the main heating heat exchange module 2, the fuel flowing inside it is heated to 150℃~160℃ high-pressure high-temperature fuel. The pressure regulating pilot valve 52 contains precision control components and cannot withstand high-temperature fuel above 150℃ for extended periods. If high-temperature fuel above 150℃ is directly introduced into the pressure regulating pilot valve 52, it may lead to seal failure and control malfunction.

[0090] To address component failure caused by extreme high temperatures, the high-pressure inlet regulating module 5 is equipped with a local high-pressure cooler 53. The local high-pressure cooler 53 is located between the pilot sampling port of the main pressure regulating valve 51 and the inlet of the pressure regulating pilot valve 52. The local high-pressure cooler 53 is a custom-designed shell-and-tube high-pressure cooler with a tube-side design flow rate of 10 L / min and a maximum withstand pressure of 25 MPa.

[0091] During actual system operation: most of the 160°C high-pressure high-temperature fuel is delivered to the tested servo valve via the main oil circuit of the main pressure regulating valve 51 to meet the high-temperature test requirements; at the same time, the main pressure regulating valve 51 separates a small stream of high-temperature high-pressure fuel from the pilot sampling port and first enters the local high-pressure cooler 53 for cooling.

[0092] The local high-pressure cooler 53 uses the cooling water from the external chiller unit as a cold source to rapidly reduce the fuel temperature from 160°C to 100°C or even below 80°C, ensuring that the fuel temperature entering the pressure regulating pilot valve 52 is strictly below its temperature limit. The cooled high-pressure fuel enters the pressure regulating pilot valve 52, generating precise pilot hydraulic pressure, which is transmitted to the pilot control end of the main pressure regulating valve 51, thereby microscopically and precisely adjusting the overflow opening or throttling opening of the main pressure regulating valve 51.

[0093] The topology design, which places the main pressure regulating valve 51 in the high-temperature main oil circuit and uses a local high-pressure cooler 53 to independently bypass and cool the pilot control oil circuit, has a dual advantage: on the one hand, it ensures that the fluid inlet pressure control accuracy is not affected by the pressure drop fluctuation of the main heating heat exchange module 2; on the other hand, it perfectly solves the problem of survival and long-term stable operation of the high-precision pressure regulating pilot valve 52 in extreme high-temperature environments, and greatly improves the overall test reliability of the aircraft fuel servo valve high-temperature test system.

[0094] In some embodiments, the high-pressure inlet pressure regulating module 5 further includes a first electro-proportional valve 54. Specifically, the first electro-proportional valve 54 may have an adjustment range of 0–75 psi, a control accuracy of ±0.2% of full scale, and an inlet / outlet thread of 1 / 8 inch NPT (national pipe thread standard). The first electro-proportional valve 54 is used to receive control signals from the controller 3 and accurately convert the received 4–20 mA analog control current into a corresponding proportional regulating air pressure output to the pressure regulating pilot valve 52.

[0095] The high-pressure pump 13 includes a plunger pump driven by a variable frequency drive motor, specifically a 40 mL / r axial plunger pump. The variable frequency drive motor is an explosion-proof, variable frequency speed-regulating three-phase asynchronous motor with a rated power of 22 kW, and its speed range can be steplessly adjusted between 400 r / min and 1000 r / min.

[0096] Controller 3 is configured to execute a collaborative closed-loop control strategy combining macroscopic and microscopic control. Specifically, controller 3 acquires the fuel pressure feedback signal collected by the pressure sensor located at the fluid inlet of the fuel servo valve of the aircraft under test, compares the actual pressure value with the preset target test pressure value, and calculates the pressure deviation. Based on this pressure deviation, controller 3 synchronously and collaboratively adjusts the speed of the variable frequency drive motor and the proportional regulating air pressure output by the first electro-proportional valve 54.

[0097] At the macroscopic flow regulation level, controller 3 adjusts the motor speed in real time by outputting frequency control commands to the inverter of the variable frequency drive motor. The speed of the variable frequency drive motor directly determines the output displacement of the plunger pump of high-pressure pump 13, thereby changing the system's basic flow rate entering the main heating heat exchange module 2.

[0098] When the required fuel flow rate for testing is low or the target test pressure is low, controller 3 actively reduces the motor speed, thereby reducing the system's base flow rate. This control method, which directly reduces redundant fluid output at the power source, effectively avoids the problem of severe system overheating caused by a large amount of excess high-pressure fuel being forced to overflow from the overflow circuit when the high-pressure pump 13 is running at full speed. This reduces the load on the system's heat dissipation module and achieves an overall reduction in energy consumption.

[0099] At the level of precise micro-pressure regulation, the controller 3 outputs a control current of 4-20mA to the first electro-proportional valve 54 based on the pressure deviation, precisely adjusting the output proportional regulating air pressure. The proportional regulating air pressure directly acts on the control chamber inside the pressure regulating pilot valve 52, driving the pressure regulating pilot valve 52 to establish the corresponding pilot hydraulic pressure.

[0100] The pilot hydraulic pressure then acts on the pilot control end of the main pressure regulating valve 51. By changing the magnitude of the pilot hydraulic pressure, the movement position of the valve core inside the main pressure regulating valve 51 is precisely controlled, ultimately changing the overflow opening of the main pressure regulating valve 51. The change in the overflow opening of the main pressure regulating valve 51 enables extremely rapid pressure relief and fine-tuning of the high-pressure, high-temperature fuel flowing through the main heating heat exchange module 2.

[0101] By adjusting the speed of the variable frequency drive motor to change the system's basic flow rate, and through deep synergy with the fluid throttling and overflow mechanism that adjusts the air pressure of the first electro-proportional valve 54 to change the overflow opening of the main pressure regulating valve 51, the high-temperature testing system for aircraft fuel servo valves achieves a dual core advantage:

[0102] Firstly, it can perform continuous wide-range closed-loop control of the fluid inlet fuel pressure within the range of 0.5MPa to 21MPa;

[0103] Secondly, it eliminates the pressure dead zone and high-frequency pressure oscillation problems that easily occur in single mechanical pressure regulating valves during wide-range pressure regulation.

[0104] The coordinated operation of the aforementioned physical structure and control algorithm ensures extremely high precision, long-term stability, and extremely fast dynamic response speed in the fluid inlet pressure control of the fuel servo valve of the aircraft under test, fully meeting the extremely stringent testing standards in the aviation field.

[0105] In some embodiments, such as Figure 3 As shown, the main heating and heat exchange module 2 includes a spiral wound tube heat exchanger 21 and a hot oil generator unit 22. The spiral wound tube heat exchanger 21 is specifically selected as a heat exchange device with a heat exchange area of ​​10 m² and a pressure resistance of 21 MPa. Its tube side is connected between the outlet of the high-pressure pump 13 and the fluid inlet of the fuel servo valve of the aircraft under test, while its shell side is in a closed-loop connection with the hot oil generator unit 22. The hot oil generator unit 22 is an explosion-proof high-temperature hot oil generator with a heating power of 60 kW, electrically connected to the controller 3. It uses internal electric heating elements to heat the hot oil to a maximum of 200°C and then delivers the hot oil to the shell side of the spiral wound tube heat exchanger 21 via a high-temperature oil pump. High-pressure, sub-high-temperature fuel flows within the tube side of the spiral wound tube heat exchanger 21, while the high-temperature hot oil flows in a counter-current or cross-flow manner within the shell side. The two undergo intense heat exchange through the tube walls.

[0106] The controller 3 is used to synchronously adjust the heating power of the oil heater unit 22 based on the fuel temperature feedback signal, thereby regulating the heating power of the main heating heat exchange module. Simultaneously, it controls the flow distribution ratio of the return oil diversion module 4, forming a closed-loop temperature control circuit to achieve rapid fuel temperature rise. In this embodiment, rapid temperature rise is to protect the high-pressure pump 13 from the harsh conditions of high temperature and high pressure. The aircraft fuel servo valve high-temperature test system abandons the traditional approach of heating the entire fuel tank 11. Instead, the fuel pumped by the high-pressure pump 13, with a maximum temperature not exceeding 120°C, is used to generate a huge temperature gradient within a very short physical tube pass by a 60kW high-power heat exchanger 21, directly and rapidly raising the fuel temperature from approximately 90°C to the target test temperature of 160°C in one go.

[0107] Controller 3 plays a crucial coordinating role in this process. When the fuel temperature feedback signal indicates that the fluid inlet temperature is below standard, controller 3 not only increases the output temperature and flow rate of the heat transfer oil from the heat exchanger unit 22, but also fine-tunes the opening of the return oil diversion module 4. This allows more return oil with a certain base temperature to circulate to the inlet of the high-pressure pump 13, thereby increasing the base temperature of the fuel entering the spiral wound tube heat exchanger 21 and reducing its heat exchange load. Through synchronous and coordinated closed-loop regulation of the heat transfer oil unit power and fuel flow distribution ratio, the aircraft fuel servo valve high-temperature test system can achieve high-precision medium temperature control with a steady-state control accuracy of ±2℃.

[0108] In some embodiments, such as Figure 4 As shown, the return oil diversion module 4 includes a three-way diversion type regulating valve 41, specifically a pneumatic diaphragm type three-way diversion type regulating valve with a nominal diameter of 20mm and a temperature resistance of 160℃. The three-way diversion type regulating valve 41 has linear flow regulation characteristics, and the material of the flow-through components is stainless steel that is resistant to high temperature and aviation kerosene corrosion.

[0109] The system also includes a return oil back pressure regulating module 6, located between the return oil port of the fuel servo valve V of the aircraft under test and the three-way diverter regulating valve 41. The function of the return oil back pressure regulating module 6 is to simulate the real back pressure environment of the aircraft engine and maintain the pressure stability at the return oil port of the fuel servo valve V of the aircraft under test.

[0110] The return oil back pressure regulating module 6 includes a back pressure valve 61 and a second electro-proportional valve 62. The back pressure valve 61 can be a pneumatically controlled back pressure valve with a regulating pressure range of 0.1 to 10 MPa and a gas-liquid pilot ratio of 1:18; the second electro-proportional valve 62 can be a proportional valve with a regulating range of 0 to 50 psi.

[0111] The second electro-proportional valve 62 receives control signals from the controller 3. The controller 3 first reads the return oil pressure feedback value measured by the pressure sensor located between the return oil port and the back pressure valve 61. The controller 3 calculates the difference between the current return oil pressure and the set back pressure target value and outputs a control signal to the second electro-proportional valve 62. The second electro-proportional valve 62 adjusts and outputs proportional air pressure to the pilot port of the back pressure valve 61 according to the strength of the electrical signal. The main valve core of the back pressure valve 61 moves under the combined action of the pilot proportional air pressure and its own main spring, changing the flow area of ​​the return oil throttle port, thereby generating a corresponding resistance pressure drop to regulate the return oil pressure of the tested aircraft fuel servo valve V in a closed loop.

[0112] After being depressurized by the back pressure valve 61, the high-temperature fuel then enters the three-way diverter valve 41, which determines whether this portion of low-pressure, high-temperature fuel returns to the high-pressure pump 13 or flows back to the fuel tank 11. This multi-stage series back pressure control and diversion control architecture ensures that pressure regulation and temperature regulation are independent and do not interfere with each other, greatly improving the dynamic response stability of the test system.

[0113] refer to Figure 5 In some embodiments, to mitigate flow pulsations in the high-pressure pump 13 and pressure shocks caused by frequent flow path switching of the fuel servo valve V of the tested aircraft during dynamic testing, an accumulator protection module 130 is connected in parallel on the outlet pipe of the high-pressure pump 13. The accumulator protection module 130 includes a high-pressure piston accumulator 131, a medium-pressure piston accumulator branch 132, and a low-pressure piston accumulator branch 133. All three accumulators can be high-temperature piston accumulators with a nominal volume of 0.95L, a pressure resistance of 31.5MPa, and a temperature resistance of 150℃.

[0114] Among them, the high-pressure piston accumulator 131 is a high-temperature resistant energy storage element used to continuously absorb fluid flow pulsations and smooth out pressure shocks caused by frequent switching of the fuel servo valve when the system is in the high-pressure test range.

[0115] The medium-pressure piston accumulator is specifically designed for medium-pressure test conditions. When the system oil supply pressure reaches a medium-set protection threshold (such as 11MPa), the controller 3 automatically controls the pneumatic valve to isolate and release the pressure, thus preventing the internal piston from being damaged by excessive compression.

[0116] The low-pressure piston accumulator is a pulsation absorption element specifically designed for low-pressure test conditions. When the system oil supply pressure reaches a lower set protection threshold (such as 4MPa), it automatically disconnects from the high-pressure oil supply main line and performs pressure relief protection.

[0117] The medium-pressure piston accumulator branch 132 includes a medium-pressure piston accumulator 1321, a first ball valve 1322, a second ball valve 1323, and a first pressure switch 1324. The medium-pressure piston accumulator 1321 is connected to the outlet pipeline of the high-pressure pump 13 through the first ball valve 1322, and to the oil tank 11 through the second ball valve 1323. The first pressure switch 1324 is located at the inlet of the medium-pressure piston accumulator 1321, and can be a pressure switch with a set pressure of 11 MPa.

[0118] The low-pressure piston accumulator branch 133 includes a low-pressure piston accumulator 1331, a third ball valve 1332, and a second pressure switch 1333. The low-pressure piston accumulator 1331 is connected to the outlet pipeline of the high-pressure pump 13 through the third ball valve 1332. The second pressure switch 1333 is located at the inlet of the low-pressure piston accumulator 1331 and is selected as a pressure switch with a set pressure of 4MPa. The controller 3 is electrically connected to the first pressure switch 1324, the second pressure switch 1333, the first ball valve 1322, the second ball valve 1323, and the third ball valve 1332.

[0119] Accumulators with different nitrogen charging pressures only have a good pulsation absorption effect within a specific system operating pressure range. If the system operating pressure is much higher than the accumulator's design pre-charge pressure, the piston inside the accumulator will be over-compressed to its limit position, which will not only lose its buffering effect but also damage the accumulator seals.

[0120] Therefore, when the system is under high-pressure testing conditions, and the oil supply pressure reaches the set protection threshold of 11 MPa for the intermediate-pressure piston accumulator 1321, the first pressure switch 1324 sends a trigger signal to the controller 3. The controller 3 controls the first ball valve 1322 to close, cutting off the connection between the intermediate-pressure piston accumulator 1321 and the outlet pipeline, and simultaneously controls the second ball valve 1323 to open, allowing the high-pressure oil inside the intermediate-pressure piston accumulator 1321 to be released into the oil tank 11, thereby disconnecting the intermediate-pressure piston accumulator 1321 from the high-pressure oil supply line and releasing pressure.

[0121] Similarly, when the oil supply pressure reaches the set protection threshold of the low-pressure piston accumulator 1331, i.e., 4MPa, the second pressure switch 1333 is triggered, and the controller 3 controls the third ball valve 1332 to close, so that the low-pressure piston accumulator 1331 is disconnected from the high-pressure oil supply circuit and released pressure.

[0122] Through this intelligent multi-stage accumulator tiered input and automatic isolation and pressure relief protection mechanism, the high-temperature test system for aircraft fuel servo valves always has optimal dynamic pressure stability over a wide pressure range, ensuring that the fluctuation of the system's supply and return oil pressure is no worse than ±5% of the actual test value of the test piece.

[0123] refer to Figure 6In some embodiments, to accommodate the testing requirements of the aircraft fuel servo valve V under test having large flow differences under different operating conditions, a wide-range flow measurement module 7 is provided between the main heating heat exchange module 2 and the aircraft fuel servo valve V under test. The wide-range flow measurement module 7 includes a main pipeline 71, and a small-range measurement branch 72 and a bypass branch 73 connected in parallel on the main pipeline 71.

[0124] A first flow meter 711 is connected in series on the main pipeline 71; a large-range gear flow meter with a flow rate of 0.2 to 40 L / min can be selected. A second flow meter 721 is connected in series on the small-range measuring branch 72; a small-range gear flow meter with a flow rate of 0.02 to 4 L / min can be selected. A high-temperature ball valve 731 is installed on the bypass branch 73; an explosion-proof ball valve with a pressure resistance of 250 bar and a temperature resistance of 160℃ can be selected. The flow rate of the first flow meter 711 is greater than that of the second flow meter 721.

[0125] During high-flow-rate testing, controller 3 keeps the high-temperature ball valve 731 open. Because the flow resistance of the branch containing the second flowmeter 721 is much greater than that of the bypass branch 73, most of the fuel flows directly through the high-temperature ball valve 731 to the fuel servo valve V of the aircraft under test. At this time, controller 3 collects the output pulse signal of the first flowmeter 711 as the basis for measuring the current total system flow. However, when the test flow is in the low-flow range, such as when it is necessary to accurately measure the minute internal leakage of the fuel servo valve V of the aircraft under test, the measurement error of the large-range first flowmeter 711 increases sharply in the low-flow range. At this time, controller 3 issues a command to close the high-temperature ball valve 731 on the bypass branch 73. After the high-temperature ball valve 731 closes, the bypass branch 73 is physically cut off, thus forcing all the fuel to flow through the small-range measurement branch 72. The fuel drives the precision gear inside the second flowmeter 721 to rotate, and controller 3 synchronously switches the data acquisition channel, collecting the direction and frequency signals with extremely high resolution output from the second flowmeter 721 as the flow measurement signal.

[0126] This hardware architecture and control logic, which allows for intelligent switching between large and small flow meters, ensures both the flow capacity for testing the dynamic characteristics of large flow rates in aircraft fuel servo valves and the stringent accuracy requirements for testing static micro-leakage, eliminating the problem that a single flow meter cannot simultaneously achieve both wide range and absolute accuracy.

[0127] In some embodiments, the system further includes an online particle size analyzer for detecting the cleanliness of the supply and return oil media. The online particle size analyzer may be an explosion-proof online particle counter with a measurement accuracy of ±0.2 contamination levels.

[0128] The pilot stage of an aircraft fuel servo valve is a precision control stage within the servo valve, employing a nozzle baffle or jet tube structure. It outputs minute control signals to drive the main valve stage, making it a core component for precise fuel pressure and flow regulation. The pilot stage of an aircraft fuel servo valve typically includes tiny nozzle baffles or jet tube structures and is extremely sensitive to the contamination level of the working medium, requiring a contamination level of at least level 7 according to relevant military standards. Therefore, real-time monitoring of fuel cleanliness is a necessary component of the testing system. However, the physical pressure limit of the optical and electronic sensing elements inside online particle size analyzers is typically only around 1 MPa, which cannot withstand the high operating pressure of up to 21 MPa in the testing system, nor can it withstand long-term temperatures above 150°C.

[0129] Therefore, the sampling inlet of the online particle size analyzer is connected to the system's fuel supply line and return line via a high-pressure resistant needle valve. The high-pressure resistant needle valve is a cartridge-type needle valve with a nominal diameter of 6mm and a pressure resistance of 25MPa. It is configured to open during sampling and measurement to throttle and regulate the fuel flow into the online particle size analyzer; and to close during non-measurement to isolate the online particle size analyzer from the physical impact of high-temperature and high-pressure fuel.

[0130] In practice, when sampling fuel in the pipeline for contamination, the operator or control system very slowly and precisely opens the corresponding high-pressure resistant needle valve. As the high-temperature, high-pressure fuel flows through the extremely small throttling gap of the needle valve, a drastic throttling and pressure reduction effect occurs, forcibly reducing the pressure from tens of MPa to a safe range of 0.1 to 0.6 MPa. Simultaneously, the small flow of fuel naturally dissipates heat and cools in the sampling pipeline before safely entering the online particle size analyzer for optical particle counting. After the test is completed, the high-pressure resistant needle valve is immediately closed.

[0131] This design cleverly solves the hardware compatibility contradiction between the delicate optical detection instrument and the extreme high temperature and high pressure test main circuit through the dual action of throttling and pressure reduction and physical cut-off of the high pressure resistant needle valve, making online oil cleanliness monitoring possible.

[0132] In some embodiments, due to the system operating in a long-term closed-loop state, the shearing work of the internal high-pressure pump 13, fluid friction along the flow path, and the inevitable heat mixing from the high-temperature return oil all cause the temperature of the system oil tank 11 to gradually increase. To eliminate this heat accumulation effect, the system is also equipped with an oil tank 11 cooling circulation filter module independent of the main test loop.

[0133] The oil tank 11 cooling circulation filtration module includes a cooling circulation pump, a circulation pipeline filter, and two stages of plate water-cooled heat exchangers connected in series. The cooling circulation pump is a stainless steel centrifugal pump with a flow rate of 3 m³ / h manufactured by Southern Pump Industry. The circulation pipeline filter includes a 5μm composite fiber filter element coarse filter and a 3μm composite fiber filter element fine filter used in series. The two stages of plate water-cooled heat exchangers are stainless steel welded heat exchangers with a total heat exchange area of ​​3.8 m² and a heat load of 65 kW.

[0134] After the cooling circulation pump starts, it continuously draws fuel from the bottom of fuel tank 11, independent of the main oil circuit testing process. The drawn fuel first undergoes deep physical interception through the 5μm and 3μm filters of the circulation pipeline filter, removing fine particulate matter generated by metal wear during system operation and colloids generated by oxidation. Subsequently, the purified fuel enters a two-stage series plate water-cooled heat exchanger. The first-stage plate heat exchanger uses 7°C cooling water provided by an external windproof chiller unit for large-temperature-difference coarse cooling, significantly reducing the temperature of the high-temperature fuel that may have mixed into fuel tank 11; the second-stage plate heat exchanger uses ambient-temperature cooling water for small-temperature-difference fine cooling. After the above deep filtration and two-stage cooling treatment, the cooled fuel finally flows back to the side of fuel tank 11 away from the fuel inlet.

[0135] The establishment of the cooling circulation filter module in fuel tank 11 is equivalent to creating a continuous dialysis and cooling internal circulation for the system fuel tank 11, so that the fuel in fuel tank 11 is always kept within the normal temperature set range of about 25°C, while maintaining extremely high physical cleanliness of the oil, providing a solid and reliable underlying oil source guarantee for the continuous high temperature and high pressure testing of the entire system.

[0136] In some embodiments, to better reproduce the real extreme working environment of the aircraft fuel servo valve within the aircraft engine nacelle, the system also includes a high-temperature environment chamber for providing a simulated high-temperature environment for the aircraft fuel servo valve V under test. The high-temperature environment chamber is a device with an internal effective volume of 1.26m × 0.8m × 1m and a maximum temperature resistance of 250°C. The aircraft fuel servo valve V under test is installed on a dedicated test platform inside the high-temperature environment chamber, and all hydraulic lines and electrical test cables are introduced into the chamber through sealed vias with silicone rubber foam insulation plugs.

[0137] Because aviation kerosene, the tested medium, is highly volatile at high temperatures, it can cause an explosion if it mixes with oxygen in the air inside the chamber and encounters a potential electrical spark or static electricity. Therefore, the high-temperature environment chamber is equipped with a nitrogen-balanced pressure-regulating explosion-proof system. This system continuously fills the chamber with inert nitrogen to displace and expel oxygen, and uses real-time interlocking monitoring via oxygen and nitrogen concentration sensors. Simultaneously, a pressure balancing device maintains a slight positive pressure inside and outside the chamber, eliminating one of the three factors that cause combustion and explosion.

[0138] Regarding the environmental heating method, the high-temperature environmental chamber is equipped with a heat transfer oil heat exchanger. Controller 3 directs an external oil pump to pump high-temperature heat transfer oil into the heat transfer oil heat exchanger inside the chamber. An explosion-proof circulating fan inside the chamber forces nitrogen-filled gas to flow across the fin surface of the heat transfer oil heat exchanger. The high-temperature heat transfer oil introduced from the outside heats and circulates the air inside the chamber, thereby enveloping the tested aircraft fuel servo valve V in a uniform high-temperature gas environment at the set temperature.

[0139] Furthermore, since high-temperature kerosene leakage is inevitable during the disassembly and reassembly of the fuel servo valve V or high-pressure pipeline joints of the aircraft under test, the high-temperature environment chamber is equipped with an inclined oil receiving tray and an oil drain valve connected to the external sealed waste oil tank 11. The dripping aviation kerosene will flow along the inclined oil receiving tray with a 50mm oil-blocking front edge to the leak port, and after being filtered by the filter screen, it will be safely and smoothly discharged into the external independent stainless steel sealed waste oil tank 11.

[0140] This series of rigorous explosion-proof and leak-proof designs, combined with the indirect heating technology of heat transfer oil, has enabled the dual extreme cross-testing and verification of the aircraft fuel servo valve under the conditions of high external environmental temperature and high internal medium temperature, while ensuring safety.

[0141] In some application scenarios, the heating power of the main heating heat exchange module is relatively large. Its inherent huge thermal inertia may cause the fluid inlet temperature of the fuel servo valve of the aircraft under test to fluctuate drastically when the test flow rate changes abruptly. Conventional proportional-integral-derivative control algorithms cannot overcome this physical hysteresis.

[0142] Therefore, this embodiment designs a transient reverse current splitting decoupling control algorithm based on thermal inertia compensation inside the controller 3.

[0143] In conventional single-loop control logic, the three-way diversion regulating valve 41 of the return oil diversion module 4 serves only as a one-way protection actuator for the high-pressure pump 13. Its sole purpose is to discharge high-temperature return oil back to the fuel tank 11 as much as possible, so that the fuel temperature monitoring signal at the inlet of the high-pressure pump 13 is as low as possible. However, the heating process of the heat transfer oil inside the main heating heat exchange module 2 is extremely slow. When the system switches from low-flow static testing to high-flow dynamic testing instantaneously, the amount of room-temperature fuel entering the main heating heat exchange module 2 increases sharply. The main heating heat exchange module 2 cannot provide enough heat in a short time, causing a significant drop in the fuel temperature at the fluid inlet.

[0144] To address this contradiction, this embodiment employs a transient reverse diversion decoupling control algorithm based on thermal inertia compensation, which breaks with conventional control thinking and transforms the temperature tolerance margin of the high-pressure pump 13 into the transient thermal compensation energy of the system.

[0145] Specifically, controller 3 monitors the instantaneous flow derivative of the system in real time, as well as the fuel temperature feedback signal at the fluid inlet of the fuel servo valve of the aircraft under test. When controller 3 predicts that a large flow change will cause severe heat overdraft in the main heating heat exchange module 2 and lead to a temperature drop, controller 3 not only sends a full-load heating command to the main heating heat exchange module 2, but also executes a transient reverse intervention action in milliseconds: controller 3 forcibly controls the pneumatic three-way diverter valve 41 to instantly increase the flow distribution ratio of the first outlet 401.

[0146] This transient action forcibly injects a large amount of high-temperature return fuel (above 150°C) that should have been returned to fuel tank 11 directly back into the inlet of high-pressure pump 13. This causes the temperature of the mixed fuel at the inlet of high-pressure pump 13 to surge instantaneously, approaching but being strictly locked below the safe critical point of 150°C by controller 3. Because the base temperature of the mixed fuel drawn into high-pressure pump 13 is instantly raised by tens of degrees, when this fuel with a relatively high base temperature enters the heat-depleted main heating heat exchange module 2, the required heat exchange temperature difference of the main heating heat exchange module 2 is instantly and significantly reduced. This control logic cleverly utilizes the transient thermal energy of the high-temperature return fuel to fill the heat gap in the main heating heat exchange module 2 during the initial heating period, smoothing out the fuel temperature drop curve at the fluid inlet of the tested aircraft's fuel servo valve.

[0147] Subsequently, as the physical temperature of the hot oil generator unit 22 inside the main heating heat exchange module 2 gradually increases and establishes sufficient steady-state heat exchange capacity, the controller 3 begins to execute a smooth decoupling exit mechanism, instructing the pneumatic three-way diverting regulating valve 41 to slowly reduce the opening of the first outlet 401, redirecting the high-temperature return oil back to the oil tank 11 for cooling by the oil tank 11 cooling circulation filter module, so that the fuel temperature monitoring signal at the inlet of the high-pressure pump 13 falls back to the low-temperature range that is beneficial to the pump body life.

[0148] This embodiment of control logic does not add physical hardware. Instead, it deeply explores and couples the boundary potential of the multivariable system in the transient process, transforming the original oil return diversion module 4, which was originally used solely for cooling protection, into a temperature compensation advanced actuator. It solves the fuel thermal shock problem under large flow change by pure algorithmic means, achieving a high-precision transient constant temperature control effect that conventional control methods do not possess.

[0149] In this embodiment, the controller 3 mainly achieves accurate flow prediction through a dual mechanism of command feedforward and signal differentiation. On the one hand, the controller 3 is responsible for issuing action commands to the fuel servo valve of the aircraft under test. At the moment of sending the large flow step test command, the controller 3 can directly know that the system will face a large flow demand before the actual physical action occurs, thereby realizing command feedforward prediction. On the other hand, the controller 3 acquires the real-time flow signal output by the wide-range flow measurement module 7 at high frequency, and calculates the instantaneous rate of change of flow by performing first derivative calculation on the signal. When the rate of change exceeds the set warning threshold, the controller 3 can calculate that there is heat energy that will be instantly evacuated by the sudden increase in cold oil, thereby accurately predicting the heat overdraft trend of the main heating heat exchange module 2 and triggering thermal inertia compensation action in advance.

[0150] In some embodiments, the complete workflow of the high-temperature testing system for aircraft fuel servo valves is as follows:

[0151] 1) Test Preparation and Environment Simulation Phase

[0152] The first step is the test preparation and environmental simulation phase, where the operator installs the aircraft fuel servo valve V under test inside a high-temperature environment chamber.

[0153] The nitrogen-balanced pressure regulating explosion-proof system of the high-temperature environment chamber starts working, filling the chamber with nitrogen to expel oxygen and prevent an explosion.

[0154] Controller 3 starts the hot oil generator unit 22. The externally input high-temperature heat transfer oil enters the heat transfer oil heat exchanger inside the high-temperature environment chamber to heat and circulate the air inside the high-temperature environment chamber, thus establishing a simulated high-temperature environment for the fuel servo valve V of the aircraft under test.

[0155] If a fuel leak occurs during the test, the leaked fuel will flow out along the inclined oil receiving pan at the bottom of the high-temperature environment chamber and be safely discharged into the closed waste oil tank 11 outside the high-temperature environment chamber through the drain valve.

[0156] At the same time, the cooling circulation filter module of fuel tank 11 begins to operate independently. The cooling circulation pump draws fuel from fuel tank 11, causing the fuel to flow through the circulation pipeline filter to remove impurities, and then through a two-stage series plate water-cooled heat exchanger for cooling, before finally returning to fuel tank 11. This ensures that the fuel in fuel tank 11 is always kept within the set temperature range and has extremely high physical cleanliness.

[0157] (ii) Oil supply boosting and pressure regulation stage

[0158] After the environment is ready, the fuel supply, pressurization, and pressure regulation phase begins. The low-pressure booster pump 12 delivers room-temperature fuel from the fuel tank 11 to the high-pressure pump 13. The controller 3 starts the variable frequency drive motor in the high-pressure pump 13, which drives the plunger pump to rotate and perform work.

[0159] During the pressurization process, the accumulator protection module 130 on the outlet pipeline of the high-pressure pump 13 plays a role in stabilizing pressure and self-protection. When the oil supply pressure gradually increases and reaches 4MPa and 11MPa respectively, the controller 3 controls the third ball valve 1332 and the first ball valve 1322 to close respectively, based on the signals from the second pressure switch 1333 and the first pressure switch 1324, and simultaneously controls the second ball valve 1323 to open. This causes the low-pressure piston accumulator 1331 and the medium-pressure piston accumulator 1321 to be disconnected from the high-pressure oil supply circuit and released pressure in sequence. This ensures stable system pressure while preventing the medium-pressure piston accumulator 1321 and the low-pressure piston accumulator 1331 from being over-compressed and damaged.

[0160] After being pressurized, the fuel then enters the high-pressure inlet pressure regulating module 5. In order to achieve the target test pressure, the controller 3 collects the fuel pressure feedback signal at the fluid inlet, macroscopically adjusts the speed of the variable frequency drive motor, and microscopically adjusts the proportional pressure output of the electro-proportional valve to the pressure regulating pilot valve 52.

[0161] To protect the pressure regulating pilot valve 52 from high temperatures, a very small amount of fuel diverted from the main fuel line is first cooled by the local high-pressure cooler 53 before entering the pressure regulating pilot valve 52. The pressure regulating pilot valve 52 generates pilot control pressure, which acts on the pilot control end of the main pressure regulating valve 51 to precisely set the fuel pressure at the fluid inlet of the fuel servo valve V of the tested aircraft.

[0162] III) Fuel Heating and Flow Measurement Stage

[0163] Simultaneously with the pressure setting, the fuel heating and flow measurement stages are performed. High-pressure fuel flows through the tube side of the spiral wound tube heat exchanger 21 in the main heating heat exchange module 2. Based on the fuel temperature feedback signal at the fluid inlet, the controller 3 synchronously adjusts the heating power output from the oil heater unit 22 to the shell side of the spiral wound tube heat exchanger 21. Combined with the flow distribution ratio of the return oil diversion module 4, the fuel is rapidly heated to the preset test temperature.

[0164] The heated, high-temperature, high-pressure fuel flows through the wide-range flow measurement module 7 before entering the fluid inlet. In high-flow-rate testing conditions, the controller 3 opens the high-temperature ball valve 731 on the bypass branch 73 and collects the signal from the first flow meter 711. In low-flow, small-leakage testing conditions, the controller 3 closes the high-temperature ball valve 731 on the bypass branch 73, forcing all the fuel to flow through the small-range measurement branch 72, and the controller 3 collects the signal from the second flow meter 721.

[0165] Throughout the fuel supply and return process, operators can open the high-pressure resistant needle valve connecting the fuel supply and return lines at any time. Utilizing the throttling and pressure-reducing effect of the needle valve, a trace amount of fuel is safely introduced into the online particulate matter analyzer for fuel cleanliness testing. After testing, the high-pressure resistant needle valve is closed to isolate pressure and temperature shocks.

[0166] (iv) Oil return back pressure control and diversion cooling stage

[0167] After the fuel flows through the fuel servo valve V of the aircraft under test to complete the test action, it enters the return fuel back pressure control and diversion cooling stage. The return fuel first flows through the return fuel back pressure adjustment module 6. The controller 3 outputs an electrical signal to the electro-proportional valve. The electro-proportional valve adjusts the proportional air pressure output to the pilot port of the back pressure valve 61, thereby controlling the return fuel pressure of the fuel servo valve V of the aircraft under test in a closed loop, simulating the real back pressure environment of an aircraft engine.

[0168] After being depressurized by the return oil back pressure regulating module 6, the high-temperature return oil enters the three-way diversion regulating valve 41 of the return oil diversion module 4. The controller 3 adjusts the opening of the three-way diversion regulating valve 41 according to the fuel temperature feedback signal at the fluid inlet and the fuel temperature monitoring signal at the inlet of the high-pressure pump 13. Part of the high-temperature return oil is distributed to the inlet of the high-pressure pump 13 through the first outlet 401 and mixed with the normal temperature fuel sent by the low-pressure booster pump 12 to maintain the safe operating temperature of the high-pressure pump 13. The remaining high-temperature return oil is discharged into the fuel tank 11 through the second outlet 402 and is cooled by the cooling circulation filter module of the fuel tank 11.

[0169] Thus, the high-temperature testing system for aircraft fuel servo valves has completed a full closed-loop workflow with high-precision temperature control, pressure control, explosion-proof safety, and self-protection functions.

[0170] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aircraft fuel servo valve high temperature test system, characterized by, include: A normal temperature oil supply module includes an oil tank and a low-pressure booster pump connected in sequence by pipelines; High-pressure pump, used to output high-pressure, sub-high-temperature fuel; The main heating heat exchange module is located between the outlet of the high-pressure pump and the fluid inlet of the fuel servo valve of the aircraft under test. It is used to heat the high-pressure sub-high-temperature fuel to a preset test temperature and output high-pressure high-temperature fuel to the fuel servo valve of the aircraft under test. The oil return diversion module has its inlet connected to the oil return port of the fuel servo valve of the aircraft under test, its first outlet connected to the inlet of the high-pressure pump, and its second outlet connected to the fuel tank. The controller is connected to the main heating heat exchange module and the oil return diversion module, respectively. The controller is used to acquire the fuel temperature feedback signal at the fluid inlet and the fuel temperature monitoring signal at the inlet of the high-pressure pump, and adjust the heating power of the main heating heat exchange module and the flow distribution ratio between the first outlet and the second outlet according to the fuel temperature feedback signal and the fuel temperature monitoring signal, so that the fuel temperature entering the fuel servo valve of the aircraft under test reaches the preset test temperature, and maintain the temperature of the mixed fuel generated after the high-temperature return oil circulating through the first outlet to the inlet of the high-pressure pump and the room temperature fuel provided by the low-pressure booster pump is within the safe operating temperature threshold of the high-pressure pump.

2. The system of claim 1, wherein, It also includes a high-voltage inlet voltage regulating module, which comprises: The main pressure regulating valve is located on the pipeline between the outlet of the main heating heat exchange module and the fluid inlet, and is used to regulate the fuel pressure at the fluid inlet; A pressure regulating pilot valve, the control port of which is connected to the pilot control terminal of the main pressure regulating valve, is used to provide pilot control pressure to the main pressure regulating valve; A local high-pressure cooler is installed between the pilot sampling port of the main pressure regulating valve and the inlet of the pressure regulating pilot valve. It is used to locally cool the high-pressure fuel introduced into the pressure regulating pilot valve so that the temperature of the fuel entering the pressure regulating pilot valve is lower than the temperature limit of the pressure regulating pilot valve.

3. The system of claim 2, wherein, The high-pressure inlet pressure regulating module also includes a first electro-proportional valve, which is used to receive the control signal from the controller and output proportional regulating air pressure to the pressure regulating pilot valve. The high-pressure pump includes a plunger pump driven by a variable frequency drive motor; The controller is configured to: acquire a fuel pressure feedback signal at the fluid inlet, calculate a pressure deviation based on the fuel pressure feedback signal, and coordinately adjust the speed of the variable frequency drive motor and the proportional regulating air pressure output by the first electro-proportional valve based on the pressure deviation; wherein, by adjusting the speed of the variable frequency drive motor, the system base flow rate entering the main heating heat exchange module is changed, and by adjusting the proportional regulating air pressure output by the first electro-proportional valve, the overflow opening of the main pressure regulating valve is changed, so as to perform wide-range closed-loop control of the fuel pressure at the fluid inlet.

4. The system according to any one of claims 1-3, characterized in that, The main heating heat exchange module includes a spiral wound tube heat exchanger and a hot oil generator unit; The tube side of the spiral wound tube heat exchanger is connected between the outlet of the high-pressure pump and the fluid inlet, and the shell side of the spiral wound tube heat exchanger is in closed-loop connection with the hot oil generator unit. The oil heater unit is electrically connected to the controller. The controller is used to adjust the heating power of the main heating heat exchange module by adjusting the heating power of the oil heater unit, thereby forming a closed-loop temperature control circuit to achieve rapid heating of the fuel.

5. The system of claim 1, wherein, The oil return diversion module includes a three-way diversion type regulating valve; The system also includes a return oil back pressure regulating module, located between the return oil port and the three-way diverting regulating valve; The return oil back pressure adjustment module includes a back pressure valve and a second electro-proportional valve; the second electro-proportional valve is used to receive the control signal from the controller, adjust and output proportional air pressure to the pilot port of the back pressure valve, so as to adjust the return oil pressure of the fuel servo valve of the aircraft under test in a closed loop.

6. The system of claim 1, wherein, An accumulator protection module is connected in parallel on the outlet pipeline of the high-pressure pump; the accumulator protection module includes a high-pressure piston accumulator, a medium-pressure piston accumulator branch and a low-pressure piston accumulator branch. The medium-pressure piston accumulator branch includes a medium-pressure piston accumulator, a first ball valve, a second ball valve, and a first pressure switch. The medium-pressure piston accumulator is connected to the outlet pipeline through the first ball valve and to the oil tank through the second ball valve. The first pressure switch is located at the inlet of the medium-pressure piston accumulator. The low-pressure piston accumulator branch includes a low-pressure piston accumulator, a third ball valve, and a second pressure switch. The low-pressure piston accumulator is connected to the outlet pipeline through the third ball valve, and the second pressure switch is located at the inlet of the low-pressure piston accumulator. The controller is electrically connected to the first pressure switch, the second pressure switch, the first ball valve, the second ball valve, and the third ball valve, respectively. When the oil supply pressure reaches the set protection threshold of the medium-pressure piston accumulator, the controller controls the first ball valve to close and the second ball valve to open, so that the medium-pressure piston accumulator is disconnected from the high-pressure oil supply circuit and released pressure; when the oil supply pressure reaches the set protection threshold of the low-pressure piston accumulator, the controller controls the third ball valve to close, so that the low-pressure piston accumulator is disconnected from the high-pressure oil supply circuit and released pressure.

7. The system of claim 1, wherein, A wide-range flow measurement module is provided between the main heating heat exchange module and the fuel servo valve of the aircraft under test. The wide-range flow measurement module includes a main pipeline and a small-range measurement branch and a bypass branch connected in parallel on the main pipeline; a first flow meter is connected in series on the main pipeline, a second flow meter is connected in series on the small-range measurement branch, and a high-temperature ball valve is installed on the bypass branch; the range of the first flow meter is greater than the range of the second flow meter. When the test flow rate is in the low flow range, the controller controls the closure of the high-temperature ball valve on the bypass branch to force all the fuel to flow through the small-range measurement branch, and collects the output of the second flow meter as the flow measurement signal.

8. The system of claim 1, wherein, It also includes an online particle size analyzer for detecting the cleanliness of the oil supply and return media; The sampling inlet of the online particle size analyzer is connected to the fuel supply line and the fuel return line respectively through a high-pressure resistant needle valve. The high-pressure resistant needle valve is configured to open during sampling and measurement to throttle and regulate the fuel flow into the online particle size analyzer, and to close during non-measurement to isolate the physical impact of high-temperature and high-pressure fuel on the online particle size analyzer.

9. The system according to claim 1, characterized in that, It also includes an oil tank cooling circulation filter module that is independent of the main test circuit; The oil tank cooling circulation filtration module includes a cooling circulation pump, a circulation pipeline filter, and two-stage plate water-cooled heat exchangers connected in sequence. The cooling circulation pump is used to draw fuel from the fuel tank, so that the fuel passes through the circulation pipeline filter and the two-stage series plate water-cooled heat exchanger for cooling before flowing back to the fuel tank, so that the fuel in the fuel tank is always kept within the set range of normal temperature.

10. The system according to claim 1, characterized in that, It also includes a high-temperature environment chamber for providing a simulated high-temperature environment for the fuel servo valve of the aircraft under test; The aircraft fuel servo valve under test is installed inside the high-temperature environment chamber; the high-temperature environment chamber has a nitrogen-filled, balanced, pressure-regulating, and explosion-proof system. The high-temperature environment chamber is equipped with a heat transfer oil heat exchanger, which heats and circulates the air inside the chamber through high-temperature heat transfer oil introduced from the outside; the bottom of the high-temperature environment chamber is equipped with an inclined oil receiving tray and an oil drain valve connected to a closed waste oil tank outside the chamber.

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