Fuel oil distribution valve with pressure relief protection function

Abstract

The fuel oil distribution valve with the pressure relief protection function comprises a shell, and a pressure building valve, a conversion valve, an auxiliary oil way valve, a main oil way valve, a first oil return way valve, a second oil return way valve and a pilot electromagnetic valve are arranged in the shell; the main structures of the pressure building valve, the auxiliary oil way valve and the main oil way valve are the same, the drift diameters of the valves are matched according to flow, the valves are in a normally-closed state under the action of spring force, the oil drainage preset value of the pressure building valve is smaller than the oil drainage preset value of the auxiliary oil way valve, and the oil drainage preset value of the auxiliary oil way valve is smaller than the oil drainage preset value of the main oil way valve. The first oil return way valve and the second oil return way valve are the same in structure and are in a normally open state under the action of spring force, and the preset closing value of the oil return way valves is smaller than the preset oil drainage value of the pressure building valve. Graded oil feeding, parking oil return and over-running oil drainage are achieved, the functions of preventing oil pumping of a main oil way, an auxiliary oil way and an oil return way are achieved, the overall structure is designed in a lightweight mode, valve assemblies can be independently disassembled and inspected, overall replacement is not needed, and the operation and maintenance cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of aircraft engine fuel system accessories, and in particular to a fuel distribution valve with pressure relief protection. Background Technology

[0002] Engine fuel systems typically use fuel distribution valves with main and auxiliary fuel lines. During engine start-up and operation, the main and auxiliary fuel lines are usually required to supply fuel simultaneously. When the engine stops, the fuel inside the fuel distributor is required to flow to the return fuel tank while the fuel supply line is cut off. This results in the main and auxiliary fuel lines of the fuel distributor being connected to the engine combustion chamber, which can easily cause the main and auxiliary fuel to flow into the return fuel line, reducing the amount of fuel supplied.

[0003] Furthermore, under high-load conditions, engines require greater power output, causing engine speed to increase accordingly. When this speed exceeds the upper limit, destructive over-revving can occur. Traditional mechanical fuel distribution valves cannot control fuel distribution timing based on engine speed, cutting off fuel supply and reducing combustion chamber power output, thus failing to provide over-rev protection and reducing engine safety and reliability. Existing technologies have the potential to stop supplying fuel to the combustion chamber under over-revving conditions, and this technology aims to address the issue of cross-flow between the main and auxiliary fuel lines and the return fuel line. Summary of the Invention

[0004] This invention prevents the main and auxiliary fuel from flowing into the return oil circuit through structural design, and adds an over-speed drain circuit for over-speed pressure relief protection. The product is a multi-functional combination valve, with each valve component modularly installed in the valve body, which has the advantages of light weight, high integration and high reliability.

[0005] The present invention provides a fuel distribution valve with pressure relief protection, comprising a housing, and the housing is provided with a pressure building valve, a switching valve, a secondary oil circuit valve, a main oil circuit valve, a first return oil circuit valve, a second return oil circuit valve, and a pilot solenoid valve; The pressure-building valve, auxiliary oil circuit valve, and main oil circuit valve have identical main structures. Their valve diameters are matched according to flow rate. Each valve is normally closed under spring force. The preset discharge value of the pressure-building valve is less than that of the auxiliary oil circuit valve, and the preset discharge value of the auxiliary oil circuit valve is less than that of the main oil circuit valve. The first and second return oil circuit valves have identical structures and are normally open under spring force. The preset closing value of the return oil circuit valve is less than that of the pressure-building valve. The pilot solenoid valve is a normally closed solenoid valve, controlled by an electrical signal to engage the armature.

[0006] One end of the pressure-building valve core is connected to the metering fuel inlet, and the other end is connected to the fuel flowing through the switching valve and the overturning drain port; the back pressure chamber of the pressure-building valve is connected to the inlet ends of the first return oil circuit valve and the second return oil circuit valve respectively.

[0007] The switching valve core is a double-ball-head valve. One side of the double-ball-head valve is connected to the pressure-building valve outlet and the over-turn drain port, and the other side is connected to the inlet of the main and auxiliary oil circuit valves. The back pressure chamber of the switching valve is connected to the metering fuel inlet and is also connected to the back pressure chambers of the first and second return oil circuit valves.

[0008] One end of the auxiliary oil circuit valve core is connected to the fuel flowing through the outlet of the switching valve, and the other end is connected to the auxiliary oil circuit outlet; one end of the main oil circuit valve core is connected to the fuel flowing through the outlet of the switching valve, and the other end is connected to the main oil circuit outlet; the back pressure chambers of the auxiliary oil circuit valve and the main oil circuit valve are interconnected, and are respectively connected to the inlet ends of the first return oil circuit valve and the second return oil circuit valve, and finally connected to the return oil port.

[0009] The outlet end of the first oil circuit valve core is connected to the outlet end of the auxiliary oil circuit valve, and they are both connected to the outlet end of the auxiliary oil circuit; the outlet end of the second oil circuit valve core is connected to the outlet end of the main oil circuit valve, and they are both connected to the outlet end of the main oil circuit.

[0010] When the metered fuel pressure is lower than the preset value for the pressure-building valve, the pressure-building valve remains closed. The back pressure chambers of the switching valve, the first return oil circuit valve, and the second return oil circuit valve are filled with oil to build up pressure, pushing their respective valve cores to actuate. This causes the switching valve to seal the over-rotation drain port and the return oil circuit valve to seal the valve inlet. At the same time, the pilot solenoid valve is filled with oil, and the solenoid valve remains closed unless it receives an electrical signal.

[0011] When the metering fuel pressure exceeds the preset discharge value of the pressure building valve, the pressure building valve opens. The switching valve, the first return valve, the second return valve, and the pilot solenoid valve remain in the above state, and the metering fuel flows through the inlet of the auxiliary valve and the main valve. If the metering fuel pressure is less than the preset discharge values ​​of the auxiliary and main valves, metering fuel will not flow out of the main and auxiliary fuel outlets. If the metering fuel pressure is greater than the preset discharge value of the auxiliary valve but less than the preset discharge value of the main valve, metering fuel will flow out of the auxiliary fuel outlet, but not from the main outlet. If the metering fuel pressure is greater than the preset discharge value of the main valve, metering fuel will flow out of both the main and auxiliary fuel outlets.

[0012] The opening status of the main and auxiliary fuel outlet channels is related to the metered fuel pressure, enabling staged fuel supply. As the metered fuel pressure gradually increases, fuel is first output from the auxiliary fuel line outlet when it reaches the opening threshold of the auxiliary fuel line valve, achieving primary fuel supply. As the pressure continues to rise and exceeds the opening threshold of the main fuel line valve, fuel supply begins from the main fuel line outlet, entering a higher-order fuel supply mode. This forms a two-stage fuel supply mechanism that automatically switches based on the pressure gradient, ensuring stable fuel supply under different operating conditions.

[0013] During the process of metering fuel flowing out of the main and auxiliary fuel outlets, the first and second return oil circuit valves are in the closed state, and the metering fuel cannot flow into the return oil port through the main and auxiliary fuel outlets, thus having the ability to prevent fuel cross-contamination.

[0014] Upon receiving an engine over-rev command, the pilot solenoid valve is energized and engages, opening the solenoid valve. Metered fuel flows rapidly into the over-rev drain port through the outlet of pilot solenoid valve 7. The back pressure chamber of the switching valve is rapidly depressurized, and the double ball valve returns to its original position under spring pressure, separating from the sealing surface of the over-rev drain port and opening it. The pressure-building valve remains open, while the first and second return valves remain closed. Metered fuel flows into the over-rev drain port through the outlet of the pressure-building valve, while simultaneously assisting the double ball valve in sealing, completely cutting off fuel supply to the main and auxiliary fuel lines.

[0015] Metered fuel flows into the over-revving drain port through the solenoid valve outlet and into the over-revving drain port through the pressure-building valve outlet, achieving dual-channel pressure relief with rapid pressure release. This allows the engine to quickly reduce the power supplied by the combustion chamber under over-revving conditions, thus reducing engine failure rate.

[0016] When the engine stops, the fuel supply to the inlet stops, the pressure-building valve closes, and the first and second return fuel circuit valves open. Back pressure in the combustion chamber blows out residual fuel from the system lines. This residual fuel flows through the main and auxiliary fuel outlets, the inlets of the first and second return fuel circuit valves, and to the return port, achieving the return fuel function. During the flow of residual fuel, it passes through the back pressure chamber of the pressure-building valve, assisting in its sealing. During the return flow, the opening of the first and second return fuel circuit valves creates a low-resistance path, ensuring rapid discharge of residual fuel and preventing fuel accumulation that could cause starting difficulties or incomplete combustion. The pressure-building valve closes tightly under back pressure, effectively isolating the inlet from the main and auxiliary fuel circuits and preventing fuel backflow. Through the coordinated action of each valve, the system achieves safe pressure relief and pipeline cleaning during the shutdown phase, ensuring stable fuel supply during the next start-up and improving overall engine reliability and responsiveness. After the residual fuel is drained, all valves return to their initial positions, and the system enters standby mode. The pressure-building valve remains closed under spring return, ensuring complete isolation between the fuel inlet and the fuel supply channel. The first and second return valves close simultaneously, blocking the return path and preventing external contaminants from entering the pipeline. The entire fuel control system achieves a closed-loop management of fuel supply, fuel cut-off, pressure relief, and protection through precise coordination, maintaining efficient and stable operation under various working conditions, providing strong support for safe engine start-up, smooth operation, and reliable shutdown. During system standby, all components remain sealed, ensuring cleanliness and stable pressure within the pipeline. Upon restarting, the fuel supply pressure at the inlet gradually builds up, the pressure-building valve rises under pressure, overcoming the spring force to open the channel, allowing fuel to flow to the combustion chamber through the main and auxiliary outlets. Precise metering and flow control, combined with speed feedback, dynamically adjust the fuel supply to achieve smooth ignition and power output. The entire control process is responsive and logically rigorous, fully meeting the engine's operating requirements under all conditions. After the pressure-building valve opens, the double ball valves simultaneously operate under pressure, cutting off the over-revving drain port passage and ensuring continuous and stable fuel supply to the main and auxiliary fuel lines. The solenoid valve adjusts its on / off state according to control commands, working in conjunction with various valves to achieve seamless switching of operating conditions. The system ensures fuel supply accuracy at different engine speeds and effectively suppresses combustion fluctuations through pressure feedback and flow matching.

[0017] Furthermore, the pilot solenoid valve is a dual-redundant solenoid valve, designed with two sets of coils. The winding method can be a radial inner-outer structure (outer coil wrapping inner coil) or an axial parallel structure. Either individual coil can attract the armature when energized, ensuring high reliability. The dual-redundant design enhances system safety and fault tolerance; even if one coil fails, the other coil can still drive the armature normally, ensuring timely pressure relief under over-revving conditions. Both radial and axial dual-coil structures meet spatial layout and electromagnetic performance requirements and facilitate maintenance and inspection. Precision machining and sealing design of the pipe connections ensure no cross-contamination between oil circuits, improving system stability. The dual-redundant design not only improves the reliability of the solenoid valve under extreme conditions but also reduces the probability of failure throughout the system's lifespan, enhancing the safety and redundancy of the engine control system.

[0018] The beneficial effects of this invention are: 1. This fuel distributor achieves the special effects and synergistic effects of staged fuel delivery, fuel return during shutdown, fuel release during over-speeding, and preventing fuel cross-contamination in the main, auxiliary, and return fuel circuits. It also has good sealing performance and high reliability.

[0019] 2. The double ball valve design forms a sealing pair with the housing under the action of spring force. It has automatic alignment and compensation capabilities during sealing, which is highly manufacturable and reduces debugging time.

[0020] 3. The fuel distributor integrates various valve components onto a complex housing, resulting in a lightweight product with high ease of maintenance and inspection (individual component disassembly for inspection). The integrated design facilitates installation and maintenance, reduces the number of pipe connections, and lowers the risk of leaks. The compact layout of functional components and optimized flow channels minimize flow losses and improve system efficiency.

[0021] 4. Through the integration of multiple channels inside the casing, the main, auxiliary oil circuits and return oil circuits are completely isolated, effectively preventing fuel cross-flow.

[0022] 5. The mating surfaces are machined with high-precision grinding to ensure reliable sealing.

[0023] 6. The overall structure features a lightweight design, reducing weight while meeting strength requirements to meet the high thrust-to-weight ratio demands of aero engines. During maintenance, the valve assembly can be disassembled and inspected separately without requiring overall replacement, reducing operating costs. It exhibits excellent stability and durability during long-term operation.

[0024] 7. The fuel distributor maintains excellent performance under extreme temperature and vibration conditions, demonstrating outstanding environmental adaptability. The overall design, through multiple redundancies and functional integration, significantly improves system reliability and maintainability, making it suitable for the harsh operating environments of high-load aero-engine plants. The modular architecture design allows for multiple models to be adapted to different engine platforms, enhancing versatility and scalability. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0026] Figure 1 A schematic diagram of the principle structure of the fuel distribution valve for pressure relief protection provided by the present invention; Figure 2 A schematic diagram of the low-pressure build-up state structure of the fuel distribution valve for pressure relief protection provided by the present invention; Figure 3 A schematic diagram of the high-pressure main and auxiliary fuel outflow state structure of the fuel distribution valve for pressure relief protection provided by the present invention. Figure 4 A schematic diagram of the over-rotation oil discharge state structure of the fuel distribution valve for pressure relief protection provided by the present invention; Figure 5 A schematic diagram of the structure of the fuel distribution valve for pressure relief protection provided by the present invention in the shutdown oil return state; Figure 6 A schematic diagram of the fuel distribution valve with pressure relief protection provided by the present invention. Wherein: 1-Pressure building valve, 2-Transfer valve, 3-Auxiliary oil circuit valve, 4-Main oil circuit valve, 5-First return oil circuit valve, 6-Second return oil circuit valve, 7-Pilot solenoid valve, 8-Housing, 8.1-Over-rotation drain port, 8.2-Auxiliary oil circuit outlet, 8.3-Main oil circuit outlet, 8.4-Return oil port, 8.5-Inlet oil port. Detailed Implementation

[0027] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the invention will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0028] Please see Figure 1 , 6 The figure shows a schematic diagram of the fuel distribution valve structure for pressure relief protection provided by the present invention, including a housing 8, and a pressure building valve 1, a switching valve 2, a secondary oil circuit valve 3, a main oil circuit valve 4, a first return oil circuit valve 5, a second return oil circuit valve 6 and a pilot solenoid valve 7 are provided inside the housing 8. The pressure-building valve 1, auxiliary oil circuit valve 3, and main oil circuit valve 4 have the same main structure. Their valve diameters are matched according to flow rate. Each valve is normally closed under spring force. The preset discharge value of pressure-building valve 1 is less than that of auxiliary oil circuit valve 3, and the preset discharge value of auxiliary oil circuit valve 3 is less than that of main oil circuit valve 4. The first return oil circuit valve 5 and the second return oil circuit valve 6 have the same structure. They are normally open under spring force, and the preset closing value of the return oil circuit valve is less than the preset discharge value of pressure-building valve 1. The pilot solenoid valve 7 is a normally closed solenoid valve that receives an electrical signal to control the armature to engage.

[0029] One end of the valve core of the pressure building valve 1 is connected to the metering fuel inlet, and the other end is connected to the fuel flowing through the switching valve 2 and the overturning drain port; the back pressure chamber of the pressure building valve 1 is connected to the inlet end of the first return oil circuit valve 5 and the second return oil circuit valve 6 respectively.

[0030] The valve core of the switching valve 2 is a double-ball valve. One side of the double-ball valve is connected to the outlet of the pressure-building valve and the over-turn drain port, and the other side is connected to the inlet of the main and auxiliary oil circuit valves. The back pressure chamber of the switching valve 2 is connected to the metering fuel inlet and is also connected to the back pressure chambers of the first return oil circuit valve 5 and the second return oil circuit valve 6.

[0031] One end of the valve core of the auxiliary oil circuit valve 3 is connected to the fuel flowing through the outlet of the switching valve 2, and the other end is connected to the outlet of the auxiliary oil circuit; one end of the valve core of the main oil circuit valve 4 is connected to the fuel flowing through the outlet of the switching valve 2, and the other end is connected to the outlet of the main oil circuit; the back pressure chambers of the auxiliary oil circuit valve 3 and the main oil circuit valve 4 are interconnected, and are respectively connected to the inlet ends of the first return oil circuit valve 5 and the second return oil circuit valve 6, and finally connected to the return oil port.

[0032] The outlet end of valve core 5 in the first oil circuit is connected to the outlet end of valve core 3 in the auxiliary oil circuit, and together they are connected to the outlet end of the auxiliary oil circuit; the outlet end of valve core 6 in the second oil circuit is connected to the outlet end of valve core 4 in the main oil circuit, and together they are connected to the outlet end of the main oil circuit.

[0033] The pilot solenoid valve 7 is a dual-redundant solenoid valve, designed with two sets of coils. The winding method can be a radial inner and outer structure (outer coil wraps inner coil) or an axial parallel structure. The armature can be attracted when either individual coil is energized, resulting in high reliability.

[0034] like Figure 2 As shown, when the metered fuel pressure is less than the preset value for the pressure-building valve 1, the pressure-building valve 1 remains closed. The back pressure chambers of the switching valve 2, the first return valve 5, and the second return valve 6 are filled with oil to build pressure, pushing their respective valve cores to actuate. This causes the switching valve 2 to seal the over-rotation drain port and the return valve to seal the valve inlet. Simultaneously, the pilot solenoid valve is filled with oil, and the solenoid valve remains closed unless it receives an electrical signal.

[0035] When the metering fuel pressure exceeds the preset discharge value of pressure-building valve 1, pressure-building valve 1 opens. Switching valve 2, first return valve 5, second return valve 6, and pilot solenoid valve 7 maintain the state where the metering fuel pressure is less than the preset discharge value of pressure-building valve 1. Metering fuel flows through the inlets of auxiliary valve 3 and main valve 4. If the metering fuel pressure is less than the preset discharge values ​​of auxiliary valve 3 and main valve 4, metering fuel will not flow from the main or auxiliary fuel outlets. If the metering fuel pressure is greater than the preset discharge value of auxiliary valve 3 but less than the preset discharge value of main valve 4, metering fuel will flow from the auxiliary fuel outlet, but not from the main fuel outlet. If the metering fuel pressure is greater than the preset discharge value of main valve 4, metering fuel will flow from both the main and auxiliary fuel outlets. The opening state of the main and auxiliary fuel outlet channels is related to the metering fuel pressure, enabling tiered fuel supply.

[0036] like Figure 3 As shown, during the process of metering fuel flowing out of the main and auxiliary fuel outlets, the first return oil circuit valve 5 and the second return oil circuit valve 6 are in the closed state, and the metering fuel cannot flow into the return oil port through the main and auxiliary fuel outlets, thus having the ability to prevent fuel cross-contamination.

[0037] like Figure 4 As shown, upon receiving an engine over-rev command, pilot solenoid valve 7 is energized and engages, opening the solenoid valve. Metered fuel flows rapidly into the over-rev drain port through the outlet of pilot solenoid valve 7. The back pressure chamber of switching valve 2 is rapidly depressurized, and the double ball valve returns to its original position under spring pressure, separating from the sealing surface of the over-rev drain port and opening it. Pressure-building valve 1 remains open, while the first and second return valves remain closed. Metered fuel flows into the over-rev drain port through the outlet of pressure-building valve 1, simultaneously assisting in sealing the double ball valve and completely cutting off fuel supply to the main and auxiliary fuel circuits. Metered fuel flows into the over-rev drain port through both the outlet of solenoid valve 7 and pressure-building valve 1, achieving simultaneous depressurization through both channels with rapid depressurization. This allows the engine to quickly reduce the power supplied by the combustion chamber under over-rev conditions, lowering the engine failure rate.

[0038] like Figure 5As shown, when the engine stops, the fuel supply to the inlet stops, the pressure-building valve 1 closes, and the first return valve 5 and the second return valve 6 open. Back pressure in the combustion chamber blows out residual fuel from the system pipeline. This residual fuel flows through the main and auxiliary fuel outlets, the inlets of the first and second return valves 5 and 6, and to the return port, achieving the return function. During the flow of residual fuel, it passes through the back pressure chamber of the pressure-building valve 1, assisting in sealing the valve. This ensures that there is no residual pressure in the fuel system when the engine is stopped, preventing fuel supply delays or pressure fluctuations during restart. During the residual fuel return process, the switching valve 2 remains closed under spring action, ensuring a reliable seal at the over-rotation drain port and preventing fuel backflow. The entire system completes self-cleaning under no-pressure conditions, ensuring the cleanliness of the pipeline interior. Upon restarting, the pressure-building valve 1 opens rapidly as the inlet pressure is rebuilt, and the system sequentially resumes its staged fuel supply function, achieving a smooth transition during start-stop. This design balances safety and reliability, effectively improving the engine's overall operational stability. Through a staged fuel supply and dual-channel pressure relief mechanism, the system achieves precise fuel regulation under different operating conditions. It features rapid over-revving response, thorough fuel return during shutdown, and smooth start-up, significantly reducing the risk of failure. The compact structural design and reliable valve linkage, combined with anti-fuel cross-contamination, self-cleaning, and seal maintenance functions, enhance overall operational stability. This solution effectively extends the service life of the fuel system and is suitable for aerospace power platforms with high reliability requirements.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, are all covered within the scope of the claims of the present invention.

Claims

1. A fuel distribution valve with pressure relief protection, characterized in that: Includes housing (8), inside which are provided a pressure building valve (1), a switching valve (2), a secondary oil circuit valve (3), a main oil circuit valve (4), a first return oil circuit valve (5), a second return oil circuit valve (6), and a pilot solenoid valve (7); The main structures of the pressure building valve (1), the auxiliary oil circuit valve (3), and the main oil circuit valve (4) are the same. The valve diameter is matched according to the flow rate. Each valve is normally closed under the action of spring force. The oil discharge preset value of the pressure building valve (1) is less than the oil discharge preset value of the auxiliary oil circuit valve (3). The oil discharge preset value of the auxiliary oil circuit valve (3) is less than the oil discharge preset value of the main oil circuit valve (4). The first return oil circuit valve (5) and the second return oil circuit valve (6) have the same structure. Each valve is normally open under the action of spring force. The closing preset values ​​of the first return oil circuit valve (5) and the second return oil circuit valve (6) are both less than the oil discharge preset value of the pressure building valve (1). The pilot solenoid valve (7) is a normally closed solenoid valve. It receives an electrical signal to control the armature to close. One end of the valve core of the pressure building valve (1) is connected to the metering fuel inlet (8.5), and the other end is connected to the fuel flowing through the switching valve (2) and the over-turning drain port (8.1) of the housing (8); the back pressure chamber of the pressure building valve (1) is connected to the inlet end of the first return oil circuit valve (5) and the second return oil circuit valve (6) respectively; The valve core of the switching valve (2) is a double ball valve. One side of the double ball valve is connected to the outlet of the pressure building valve (1) and the overturn oil drain port (8.1), and the other side is connected to the inlet of the auxiliary oil circuit valve (3) and the main oil circuit valve (4). The back pressure chamber of the switching valve (2) is connected to the metering fuel inlet (8.5) and is also connected to the back pressure chambers of the first return oil circuit valve (5) and the second return oil circuit valve (6). One end of the valve core of the auxiliary oil circuit valve (3) is connected to the fuel flowing through the outlet of the switching valve (2), and the other end is connected to the auxiliary oil circuit outlet (8.2) of the housing (8); one end of the valve core of the main oil circuit valve (4) is connected to the fuel flowing through the outlet of the switching valve (2), and the other end is connected to the main oil circuit outlet (8.3) of the housing (8); the back pressure chambers of the auxiliary oil circuit valve (3) and the main oil circuit valve (4) are interconnected, and are respectively connected to the inlet ends of the first return oil circuit valve (5) and the second return oil circuit valve (6), and finally connected to the return oil port (8.4) of the housing (8); The outlet end of the first oil circuit valve (5) is connected to the other end of the outlet of the auxiliary oil circuit valve (3), and together they are connected to the outlet of the auxiliary oil circuit (8.2); the outlet end of the second oil circuit valve (6) is connected to the other end of the outlet of the main oil circuit valve (4), and together they are connected to the outlet of the main oil circuit (8.3).

2. The fuel distribution valve with pressure relief protection according to claim 1, characterized in that: When the metered fuel pressure is less than the preset value of the pressure building valve (1), the pressure building valve (1) remains closed. The back pressure chambers of the switching valve (2), the first return valve (5), and the second return valve (6) are filled with oil to build pressure, which pushes their respective valve cores to move. This causes the switching valve (2) to seal the overturned oil drain port (8.1), the inlet of the first return valve (5), and the second return valve (6). At the same time, the inner cavity of the pilot solenoid valve (7) is filled with oil. The solenoid valve remains closed as long as it does not receive an electrical signal.

3. The fuel distribution valve with pressure relief protection according to claim 1, characterized in that: When the metering fuel pressure is greater than the preset value of the pressure building valve (1), the pressure building valve (1) opens. The switching valve (2), the first return valve (5), the second return valve (6), and the pilot solenoid valve (7) maintain the state where the metering fuel pressure is less than the preset value of the pressure building valve (1). The metering fuel flows through the inlet of the auxiliary valve (3) and the main valve (4). If the metering fuel pressure is less than the preset value of the discharge of the auxiliary valve (3) and the main valve (4), the metering fuel will not flow out of the auxiliary outlet (8.2) and the main outlet (8.3). If the metering fuel pressure is greater than the preset value of the discharge of the auxiliary valve (3) and the main valve (4), the metering fuel will not flow out of the auxiliary outlet (8.2) and the main outlet (8.3). If the oil discharge preset value of the auxiliary oil circuit valve (3) is less than the oil discharge preset value of the main oil circuit valve (4), metered fuel will flow out of the auxiliary oil circuit outlet (8.2), while metered fuel will not flow out of the main oil circuit outlet (8.3). If the metered fuel pressure is greater than the oil discharge preset value of the main oil circuit valve (4), metered fuel will flow out of both the auxiliary oil circuit outlet (8.2) and the main oil circuit outlet (8.3). During this process, the first return oil circuit valve (5) and the second return oil circuit valve (6) are in the closed state. The auxiliary oil circuit outlet (8.2) and the main oil circuit outlet (8.3) are related to the metered fuel pressure, which can realize graded fuel supply.

4. The fuel distribution valve with pressure relief protection according to claim 1, characterized in that: When the engine over-rev command is received, the pilot solenoid valve (7) is energized and engaged, causing the solenoid valve to open. Metered fuel flows rapidly into the over-rev drain port (8.1) through the outlet of the pilot solenoid valve (7). The back pressure chamber of the switching valve (2) is quickly depressurized, and its double ball valve returns to its original position under the action of the spring, leaving the sealing surface of the over-rev drain port (8.1) and opening the over-rev drain port (8.1). The pressure building valve (1) remains open, while the first return oil circuit valve (5) and the second return oil circuit valve (6) remain closed. Metered fuel flows into the over-rev drain port (8.1) through the outlet of the pressure building valve (1). At the same time, the metered fuel auxiliary switching valve (2) is sealed, completely cutting off the fuel supply in the main and auxiliary oil circuits.

5. The fuel distribution valve with pressure relief protection according to claim 1, characterized in that: When the engine stops, the fuel supply at the inlet (8.5) stops, the pressure building valve (1) closes, and the first return valve (5) and the second return valve (6) open. The back pressure of the combustion chamber blows out the residual oil in the system pipeline. The residual oil flows through the auxiliary oil outlet (8.2) and the main oil outlet (8.3), the inlet of the first return valve (5) and the second return valve (6), to the return port (8.4) to realize the return oil function. The residual oil flows through the back pressure chamber of the pressure building valve (1) to help seal the pressure building valve (1).

6. The fuel distribution valve with pressure relief protection according to claim 1, characterized in that: The pilot solenoid valve (7) is a dual-redundant solenoid valve, designed with two sets of coils, and the winding method is either radial inner and outer structure or axial parallel structure.

7. The fuel distribution valve with pressure relief protection according to claim 1, characterized in that: The sealing structures of the pressure building valve (1), switching valve (2), auxiliary oil circuit valve (3), main oil circuit valve (4), first return oil circuit valve (5), and second return oil circuit valve (6) are selected according to the pressure system, using soft sealing, hard sealing, or a combination of soft sealing and hard sealing.

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