Fuel cut-off lock

Abstract

This application discloses a fuel cut-off locking device, belonging to the field of aero-engine fuel systems. It includes a pressure-holding valve body, comprising a pressure-holding valve sleeve and a pressure-holding valve core disposed within the sleeve. One end of the pressure-holding valve sleeve is provided with a first spring, and the end of the sleeve away from the first spring is provided with a metering fuel inlet and a first fuel passage window. The pressure-holding valve core moves axially along the pressure-holding valve sleeve under the combined action of the first spring and the metering fuel pressure to control the opening degree of the first fuel passage window. A locking valve is also included, with the end of the locking valve away from the metering fuel outlet forming a low-pressure fuel chamber. A bidirectional sealing structure is disposed within the locking valve, used to close the low-pressure fuel chamber inlet in a first state to guide metering fuel to the metering fuel outlet, or to close the metering fuel outlet in a second state to guide metering fuel to the low-pressure fuel chamber inlet. This application solves the technical problems of slow cut-off speed and difficulty in maintaining system pressure after cut-off in existing fuel cut-off devices.

Description

Technical Field

[0001] This application relates to the field of aircraft engine fuel systems, specifically fuel cut-off and locking devices. Background Technology

[0002] Fuel control systems are commonly found in gas turbine engines, turboshaft engines, and other aero-engines to control the supply and cutoff of metered fuel. In existing technology, the fuel cutoff function is typically achieved using a solenoid valve. When the engine receives a shutdown command, the solenoid valve closes the fuel passage and directs metered fuel to the low-pressure fuel chamber through the return port, thus achieving fuel cutoff.

[0003] However, due to the structural limitations of solenoid valves, their oil discharge capacity must be selected based on fuel flow rate, resulting in limited return efficiency and slow fuel cut-off speed, making it difficult to meet the requirements for rapid response. Simultaneously, after fuel supply is cut off, high-pressure fuel in the system directly drains into the low-pressure chamber, causing the system pressure to rapidly drop to a low-pressure level. Consequently, some hydraulic components that rely on fuel pressure for operation lose their functionality. When fuel supply is restored, these hydraulic components need to re-establish their operating pressure, resulting in a slow shutdown recovery response and affecting the reliability of the fuel system.

[0004] Therefore, existing fuel cut-off devices generally have the following problems: first, the fuel cut-off speed is slow and the response is insufficient; second, the system pressure drops rapidly to a low pressure after the cut-off, and the function of hydraulic components is limited; there is an urgent need to provide a technical solution that can maintain stable system pressure while achieving rapid fuel cut-off. Summary of the Invention

[0005] This application provides a fuel cut-off locking device to solve the technical problems of slow cutting speed and difficulty in maintaining system pressure after cutting off existing fuel cut-off devices.

[0006] According to one aspect of this application, a fuel cut-off locking device is provided, comprising a pressure-holding valve body, the pressure-holding valve body including a pressure-holding valve sleeve and a pressure-holding valve core disposed within the pressure-holding valve sleeve, a first spring being provided at one end of the pressure-holding valve sleeve, and a metering fuel inlet and a first fuel passage window being provided at the end of the pressure-holding valve sleeve away from the first spring, the pressure-holding valve core moving axially along the pressure-holding valve sleeve under the combined action of the first spring and the metering fuel pressure to control the opening degree of the first fuel passage window; a locking valve, the locking valve having a second fuel passage window and a metering fuel outlet, the second fuel passage window communicating with the first fuel passage window, the end of the locking valve away from the metering fuel outlet forming a low-pressure fuel chamber; and a bidirectional sealing structure disposed within the locking valve, used to close the low-pressure fuel chamber inlet in a first state to guide the metering fuel to the metering fuel outlet, or to close the metering fuel outlet in a second state to guide the metering fuel to the low-pressure fuel chamber inlet.

[0007] Optionally, a slider is slidably connected inside the locking valve. The slider is connected to the bidirectional sealing structure. A second spring is provided inside the locking valve to support the bidirectional sealing structure. The side of the slider away from the bidirectional sealing structure is used to bear the force of the control oil pressure, so that the slider and the bidirectional sealing structure reciprocate under the combined action of the control oil pressure and the second spring.

[0008] Optionally, the slider is provided with a connecting rod, which is connected to the ball joint of the two-way sealing structure.

[0009] Optionally, the fuel cut-off locking device also includes a solenoid valve, the input of which is connected to high-pressure fuel and low-pressure fuel respectively, and the output of which is used to select one of the high-pressure fuel or low-pressure fuel to be output as the control oil pressure for driving the slider.

[0010] Optionally, a third spring is provided in the low-pressure fuel chamber, and a sealing ball is provided at the end of the third spring. Under the combined action of the third spring force and the metering fuel pressure, the sealing ball approaches or moves away from the low-pressure fuel chamber inlet to close or open the low-pressure fuel chamber inlet.

[0011] Optionally, a positioning boss is provided in the low-pressure fuel chamber, a third spring is sleeved on the positioning boss, a support seat is provided at the end of the third spring away from the positioning boss, and a sealing ball is embedded in the support seat.

[0012] Optionally, the bidirectional sealing structure includes a sealing block, with sealing elements provided on both sides of the sealing block.

[0013] Optionally, the portion of the pressure-holding valve sleeve containing the first spring forms a first spring cavity, which is connected to the low-pressure fuel, so that the low-pressure fuel pressure and the elastic force of the first spring act together on the pressure-holding valve body to balance the pressure of the metered fuel.

[0014] Optionally, an intermediate cavity is formed between the pressure-holding valve core and the pressure-holding valve sleeve. The intermediate cavity is used to introduce high-pressure fuel, so that the high-pressure fuel enters the first spring cavity through the gap between the pressure-holding valve core and the pressure-holding valve sleeve.

[0015] Optionally, a limiting post is provided in the first spring cavity to support the end of the pressure-holding valve core and limit the stroke of the pressure-holding valve core.

[0016] In summary, this application includes at least one of the following beneficial technical effects:

[0017] This solution addresses the problems of slow fuel cut-off speed and difficulty in maintaining system pressure after cut-off in existing technologies by simultaneously incorporating a pressure-holding valve body and a locking valve into the fuel cut-off locking device. The pressure-holding valve core moves axially along the valve sleeve under the combined action of the first spring and the metered fuel pressure. By adjusting the opening of the first oil passage window, the system remains in a state of equilibrium between pressure and spring force when fuel pressure changes. When the metered fuel pressure decreases, the valve core moves towards the closing direction, narrowing the oil passage window until it is maintained at a constant opening position. This stabilizes the pressure within the fuel system near a constant value, providing a base pressure for the system under cut-off conditions and ensuring the normal operation of hydraulic components. Meanwhile, the bidirectional sealing structure on the locking valve can switch the flow path under different conditions. During normal fuel supply, it closes the low-pressure fuel chamber inlet, allowing the metered fuel to flow smoothly to the metering outlet. During shut-off, it quickly closes the metering outlet and guides the metered fuel to the low-pressure fuel chamber inlet, achieving rapid shut-off and depressurization of the metered fuel. This avoids slow response caused by fuel stagnation. Thus, a single device simultaneously achieves the functions of rapidly shutting off metered fuel and maintaining constant system pressure. This improves the response speed of fuel shut-off and ensures that the system pressure does not drop to a low-pressure level after shut-off, thereby overcoming the shortcomings of existing fuel shut-off devices, such as slow shut-off speed and poor pressure maintenance capability.

[0018] In addition to the purposes, features, and advantages described above, this application has other purposes, features, and advantages. A further detailed description of this application will be provided below with reference to the figures. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 This is a schematic diagram of the fuel cut-off locking device in normal operation.

[0021] Figure 2 This is a schematic diagram of the fuel cut-off locking device of this application after receiving a stop command.

[0022] Legend:

[0023] 1. Pressure holding valve sleeve; 2. Pressure holding valve core; 3. Locking valve; 4. Seal; 5. Second spring; 6. Third spring; 7. Bidirectional sealing structure; 8. Slider; 9. Solenoid valve; 10. Steel ball; 11. First spring; 12. Metering outlet. Detailed Implementation

[0024] The embodiments of this application are described in detail below with reference to the accompanying drawings; however, this application may be implemented in a variety of different ways as defined and covered below.

[0025] The following is in conjunction with the appendix Figures 1-2 This application will be described in further detail.

[0026] The fuel cut-off interlocking device provided by this invention is integrally installed in the fuel control system of an aero-engine, used to achieve rapid cut-off of metered fuel and stable maintenance of system pressure during normal engine operation and shutdown. As a key component of the fuel system, this device can be arranged between the metering unit and the fuel outlet, enabling the metered fuel to flow stably along a set path under both fuel supply and cut-off conditions.

[0027] This device, arranged from top to bottom along the flow path, consists of a pressure-holding valve body and a locking valve 3. The pressure-holding valve body is used to variably adjust the flow capacity of the metered fuel at the front end, while the locking valve 3 is used to switch the direction of the metered fuel in two mutually exclusive states. The pressure-holding valve body consists of a pressure-holding valve sleeve 1 and a pressure-holding valve core 2 located within the valve sleeve. A first spring 11 is installed at one end of the pressure-holding valve sleeve 1. During device operation, the pressure-holding valve core 2 moves axially along the valve sleeve under the combined action of the metered fuel pressure and the elastic force of the first spring 11, thereby changing the opening degree of the first fuel inlet window. This opening degree adjustment is not a fixed value, but rather adaptive in real time according to the pressure-spring force balance relationship: when the metering side pressure is high, the valve core displacement causes the window to enlarge accordingly, reducing the upstream pressure differential; when the metering side pressure decreases, the valve core, under spring bias, causes the window to shrink, increasing the upstream pressure differential. Therefore, the pressure-holding valve body is equivalent to a follow-up variable throttling unit, which couples and regulates the flow rate and pressure difference in a mechanical balance manner, providing controlled and relatively stable inlet conditions for the downstream locking valve 3, and suppressing the overshoot and collapse of the system pressure during the switching process.

[0028] The locking valve 3 is equipped with a second oil passage window connected to the pressure-holding valve body and a metering fuel outlet for external output. The end furthest from the metering outlet 12 forms a low-pressure fuel chamber. A bidirectional sealing structure 7 is arranged inside the locking valve 3 to reconfigure the flow path between two states: In the first state, the bidirectional sealing structure 7 closes the low-pressure fuel chamber inlet, allowing fuel from the first oil passage window to be directed only to the metering fuel outlet via the second oil passage window, completing normal fuel supply; in the second state, the bidirectional sealing structure 7 closes the metering fuel outlet, redirecting fuel entering the locking valve 3 to the low-pressure fuel chamber inlet, directly blocking the metering path and simultaneously establishing a rapid venting path. Because the sealing structure uses interlocking replacement between the two sealing surfaces, only one path connects the outlet side and the low-pressure side at any given time, avoiding parallel mixing of fuel supply and venting, and ensuring the determinism and speed of the cut-off action from a structural logic perspective.

[0029] The collaborative mechanism of the two units is reflected in the pressure management throughout the switching process: when the locking valve 3 switches from the first state to the second state, the metering outlet 12 is closed, and the fuel is diverted to the low-pressure chamber, there is an instantaneous pressure difference change from the high-pressure side to the low-pressure side in the system; at this time, the pressure-holding valve body, through the pressure-holding valve core 2, controls the opening of the first fuel window to suppress the excessively rapid decay of the upstream pressure, so that the system pressure is stabilized near a constant value; when returning from the second state to the first state to resume fuel supply, the valve core expands the window due to the rise in metering side pressure, reducing inlet loss and smoothly restoring the flow. During state switching, on the one hand, the locking valve 3 directly closes the outlet end and immediately diverts the fuel to the low-pressure chamber, shortening the cut-off path and achieving rapid cut-off; on the other hand, the mechanical balance adjustment of the pressure-holding valve body ensures that the system pressure does not drop to low pressure during the cut-off and recovery phases, thereby maintaining the functional continuity of components related to fuel pressure.

[0030] In one embodiment, a slider 8 is disposed within the locking valve 3 and connected to the bidirectional sealing structure 7. A second spring 5 is also disposed within the locking valve 3 to support the bidirectional sealing structure 7. The side of the slider 8 away from the bidirectional sealing structure 7 forms a pressure-bearing surface to withstand the force of the control oil pressure. Thus, under the combined action of the control oil pressure and the second spring 5, the slider 8 reciprocates axially along the locking valve 3, and through its linkage with the bidirectional sealing structure 7, switches the fuel flow path between two mutually exclusive states.

[0031] When the control oil pressure rises and exceeds the elastic force of the second spring 5, the slider 8 moves in the opening direction under pressure, simultaneously displacing the bidirectional sealing structure 7. This seals the low-pressure fuel chamber inlet, allowing fuel to flow through the second fuel inlet window to the metering fuel outlet, achieving normal fuel supply. When the control oil pressure drops to a level insufficient to overcome the force of the second spring 5, the second spring 5 provides a return action, pushing the slider 8 and the bidirectional sealing structure 7 to move in opposite directions. At this point, the metering fuel outlet is sealed, and fuel is guided to the low-pressure fuel chamber inlet, achieving rapid cutoff and release of metered fuel. Throughout the process, the synchronous movement of the slider 8 and the bidirectional sealing structure 7 ensures the clarity of the flow path switching, avoiding the parallel occurrence of fuel supply and release.

[0032] In addition to providing a reset function, the second spring 5 also applies a continuous clamping force to the bidirectional sealing structure 7 when the slider 8 is in position, thereby ensuring the fit and sealing effect of the sealing surface. Simultaneously, it suppresses vibrations caused by pressure fluctuations during the switching process, making the switching more stable and reliable. Thus, this solution forms a bistable switching mechanism driven by control oil pressure and biased by the second spring 5, capable of achieving clear switching of the fuel passage between fuel supply and cut-off states in a short time, and ensuring sealing reliability and response speed in each state.

[0033] In one embodiment, a connecting rod is provided on the slider 8, and the connecting rod is connected to the bidirectional sealing structure 7 via a ball joint. The axial displacement and pushing / pulling force of the slider 8 are transmitted to the bidirectional sealing structure 7 via the connecting rod. The ball joint provides multi-degree-of-freedom micro-angle compensation, so that the force transmission path is mainly dominated by the axial component, while the lateral component and eccentric bending moment are absorbed during the spherical rotation. Therefore, the linear motion of the slider 8 is reliably transmitted to the sealing component at a constant amplitude, while allowing the sealing component to produce slight pitch / yaw relative to the slider 8 for self-alignment. During operation, when the slider 8 advances, it applies axial force to the bidirectional sealing structure 7 through the connecting rod. The ball joint allows the sealing structure to make slight angular adjustments around the center of the ball, so that it forms a uniform fit with the corresponding sealing seat surface, avoiding unilateral backing and local overload caused by assembly errors, geometric tolerances, or compression deformation.

[0034] In one embodiment, the fuel cut-off locking device further includes a solenoid valve 9. The input end of the solenoid valve 9 is connected to high-pressure fuel and low-pressure fuel respectively, and the output end of the solenoid valve 9 is used to select one of the high-pressure fuel or low-pressure fuel as the control oil pressure to drive the slider 8. When the coil is controlled to switch, the solenoid valve 9 completes the channel switching internally, sending only one pressure through its output end to the control oil pressure interface of the locking valve 3; the other pressure level that is not selected is reliably isolated inside the valve, avoiding the mutual crosstalk or mixing of the two pressures in the control circuit, thereby ensuring that the control end always presents a clear and single pressure state. Since the control oil pressure is directly taken from the existing high / low pressure levels of the system, there is no need to set up a separate pressurization or depressurization mechanism. The control chain is short and the pressurization and depressurization paths are clear, which provides a fast and clean pressure drive signal for subsequent valve position switching.

[0035] The control oil pressure output by solenoid valve 9 acts on the pressure-bearing surface of slider 8 away from the bidirectional sealing structure 7, forming an antagonistic relationship with the reset spring force within locking valve 3: when high-pressure fuel is selected for output, the control end receives higher pressure, the axial fluid force on slider 8 increases and overcomes the reset spring force, thereby driving the bidirectional sealing structure 7 connected to it to move in the opening direction; when low-pressure fuel is selected for output, the control end pressure decreases significantly, the fluid force on slider 8 decreases, the reset spring force dominates, and slider 8 and bidirectional sealing structure 7 move in opposite directions, establishing a seal on the other side. Locking valve 3 achieves a definite and repeatable back-and-forth switching between two mutually exclusive valve positions: when one valve position is established, only metering outlet 12 is open; when the other valve position is established, only the low-pressure fuel chamber inlet is open.

[0036] In one embodiment, a third spring 6 is provided inside the low-pressure fuel chamber, with a sealing ball connected to its end. The sealing ball is located at the inlet of the low-pressure fuel chamber and is axially opposite to the inlet. The third spring 6 provides a biasing / pressuring force towards the inlet. Under the combined action of the force of the third spring 6 and the fluid force generated by the metering fuel acting on its pressure area, the sealing ball moves closer to or away from the inlet along the inlet axis: when the sealing ball is pressed towards the inlet, a tight seal is formed, thereby closing the low-pressure fuel chamber inlet; when the sealing ball is pushed away from the inlet by the fluid force, a gap is formed, thereby opening the low-pressure fuel chamber inlet. During normal fuel supply, the sealing ball remains in contact with the inlet under the biasing action of the third spring 6. Even with minimal leakage or pressure disturbance, it forms a passive secondary barrier at the inlet side, preventing unnecessary fuel leakage from the metering side into the low-pressure chamber and improving the system's sealing margin and stability during fuel supply. Under cut-off / release conditions, the metered fuel is guided to the low-pressure chamber inlet. The pressure at the inlet rapidly acts on the sealing ball. When the axial force generated by this pressure exceeds the resultant force of the third spring 6, the sealing ball disengages and opens, instantly opening the low-pressure chamber inlet and forming a rapid pressure relief / release pathway. As the inlet pressure decreases below a certain threshold, the third spring 6 regains dominance, and the sealing ball returns to its seat to close, preventing backflow or cavitation-induced pulsation backflow from the low-pressure chamber into the metering side.

[0037] In one embodiment, a positioning boss is provided inside the low-pressure fuel chamber, and a third spring 6 is sleeved on the positioning boss, structurally constraining the axis of the spring to be coaxial with the axis of the low-pressure fuel chamber inlet. A support seat is provided at the end of the third spring 6 away from the positioning boss, and a sealing ball is embedded in the support seat. During operation, the axial force of the third spring 6 is transmitted to the sealing ball through the support seat. Under the combined force of the spring force and the fluid pressure on the inlet side, the sealing ball moves closer to / away from the inlet along the axis, realizing the closure or opening of the low-pressure fuel chamber inlet. The support seat forms a partial enclosure and limit on the spherical surface, which not only prevents the sealing ball from dislodging or laterally moving under high-frequency vibration and fluid impact, but also allows the ball to perform slight self-alignment, so that even when there are slight misalignments caused by assembly and thermal expansion and contraction, it can still automatically achieve a surface fit with the inlet sealing surface.

[0038] In one embodiment, the bidirectional sealing structure 7 includes a sealing block with sealing elements 4 on both sides. The sealing block acts as a carrier, with the sealing elements 4 on both sides facing two corresponding valve seats / sealing surfaces. Once the sealing block undergoes axial displacement within the valve cavity, one sealing element 4 can be engaged with the corresponding valve seat to establish a seal, while the other sealing element 4 remains separate from its corresponding valve seat, thus providing a structural basis for subsequent flow path "two-way selection". Coaxially integrating two sealing functions onto the same sealing block significantly shortens the switching path and action chain, reduces additional mating pairs, and improves the certainty, synchronization, and speed of switching. The symmetrical arrangement of the sealing elements 4 on both sides makes the sealing block more evenly stressed, which helps reduce the risk of uneven wear and jamming caused by lateral forces, and provides a certain degree of adaptive tolerance to assembly and form / position errors and thermally induced micro-deformation.

[0039] In one embodiment, the portion of the pressure-holding valve sleeve 1 containing the first spring 11 forms a first spring cavity. This first spring cavity is connected to the low-pressure fuel, allowing the low-pressure fuel pressure and the spring force of the first spring 11 to act together on the pressure-holding valve body to balance the pressure of the metered fuel. Thus, the forces acting on both sides of the pressure-holding valve body are: on one side, the pressure from the metered fuel; and on the other side, the resultant force of the low-pressure fuel pressure and the spring force of the first spring 11. When the metered fuel pressure rises, its driving force gradually exceeds the combined reaction force of the low-pressure fuel and the spring, causing the valve core to move in the opening direction, enlarging the first fuel passage and increasing fuel flow capacity. When the metered fuel pressure drops, the resultant force of the low-pressure fuel and the spring becomes dominant, causing the valve core to move in the closing direction, shrinking the first fuel passage and reducing fuel flow capacity. This forms a dynamic throttling regulation mechanism with low-pressure fuel as a reference and the spring as a bias.

[0040] The design of the first spring chamber being connected to the low-pressure fuel is of great significance. On the one hand, the spring chamber is always filled with low-pressure fuel, preventing it from becoming a trapped, closed cavity. This avoids valve spool lag or position drift caused by liquid compression or retention, allowing the valve spool to maintain balance and adjustment around a stable low-pressure reference. On the other hand, the low-pressure fuel pressure and spring force superimposed on one side of the valve spool create a continuous resistance to the metered fuel pressure. This ensures that the valve spool's equilibrium position exhibits a predictable unidirectional response to changes in metered pressure, keeping the opening of the first fuel inlet window always within a reasonable range.

[0041] In one embodiment, an intermediate cavity is constructed between the pressure-holding valve core 2 and the pressure-holding valve sleeve 1, and this intermediate cavity is specifically used to introduce high-pressure fuel. The high-pressure fuel does not pass directly through the main valve port across the pressure-holding valve body, but instead seeps downstream along the annular gap between the pressure-holding valve core 2 and the pressure-holding valve sleeve 1, finally entering the first spring cavity that houses the first spring 11. The intermediate cavity first collects the fuel from the high-pressure side within the intermediate cavity, and then it enters the spring cavity in a restricted gap flow form; the gap naturally provides throttling characteristics, keeping the leakage flow at a small, predictable level.

[0042] This path enables continuous micro-leakage from high pressure to low pressure, ensuring a constant supply of fresh liquid to the first spring chamber. This prevents the spring chamber from becoming a closed cavity, which could lead to pressure stagnation / cavitation and valve position drift. It also ensures the valve core remains balanced with the spring force around a defined low-pressure reference. Secondly, during operational disturbances, the annular gap leakage provides the pressure-holding valve body with inherent hydraulic damping and differential pressure self-adjustment capabilities: when the metering-side pressure surges, the leakage increases, and the spring chamber pressure transitions smoothly, helping to suppress overshoot of the preceding pressure; when the metering-side pressure drops, the leakage decreases with the pressure difference, and the valve core contracts its window under spring bias, suppressing pressure collapse.

[0043] In this structure, high-pressure fuel enters the gap between the valve core and valve sleeve through the intermediate chamber and finally flows into the first spring chamber. This not only maintains a stable liquid environment on the low-pressure side but also compensates for gap leakage. In actual operation, metering fuel inevitably leaks slightly due to the fit clearance between the valve core and valve sleeve or wear of parts. If not replenished, this loss will be directly reflected in the metering flow rate, causing actual output deviation. However, through the continuous micro-leakage in the intermediate chamber, high-pressure fuel is continuously replenished to the first spring chamber, effectively "filling" the leakage in the metering path and ensuring that the actual flow rate at metering outlet 12 matches the theoretical flow rate.

[0044] In one embodiment, a limiting post is provided in the first spring cavity. The limiting post is located on the end path of the pressure-holding valve core 2's stroke. During operation, when the valve core moves in the opening direction under the pressure of metered fuel and reaches the design limit, the end of the valve core contacts the limiting post, forming a rigid support, thereby preventing the valve core from continuing to move. The maximum opening of the first oil passage window is also locked within a controllable range to avoid pressure overshoot caused by an excessively large window due to overstroke.

[0045] The implementation principle of the fuel cut-off locking device in this embodiment is as follows: Under normal operating conditions, the solenoid valve 9 selects high-pressure fuel as the control oil pressure output. This control oil pressure acts on the pressure-bearing surface of the slider 8, pushing the slider 8 to overcome the elastic force of the second spring 5 and driving the bidirectional sealing structure 7 to move to the open position. At this time, the sealing surface of the bidirectional sealing structure 7 is in contact with the low-pressure fuel chamber inlet, thereby sealing the low-pressure chamber inlet and allowing the metered fuel to be smoothly guided to the metered fuel outlet through the first and second fuel inlets to ensure continuous fuel supply to the combustion chamber.

[0046] In the cut-off state, the control oil pressure output by solenoid valve 9 switches to low-pressure fuel. The slider 8 is not pressurized enough to overcome the elastic force of the second spring 5. Under the action of the second spring 5, the bidirectional sealing structure 7 is driven to return to the closed position. At this time, the sealing surface of the bidirectional sealing structure 7 is in contact with the metering fuel outlet side, reliably sealing the metering outlet 12. At the same time, the incoming metering fuel is guided to the low-pressure fuel chamber inlet, forming a rapid discharge path and realizing the immediate cut-off of metering fuel. In order to prevent the system pressure from suddenly dropping to a low-pressure level after the cut-off, the pressure holding valve core 2 moves in the closing direction as the pressure decreases, causing the first oil passage window to shrink until it stabilizes at a constant opening position, thereby ensuring that the system pressure is maintained near a constant value, providing the necessary basic pressure support for the continuous function of hydraulic components.

[0047] Through the above-described structural combination, the fuel cut-off locking device of the present invention can ensure a stable supply of metered fuel and constant maintenance of system pressure under normal working conditions, achieve rapid blocking and orderly release of metered fuel under cut-off conditions, and maintain the stability of system pressure during pressure changes, thereby improving the safety, responsiveness and reliability of the fuel system.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. Fuel shut-off lockout device, characterized in that include: The pressure holding valve body includes a pressure holding valve sleeve (1) and a pressure holding valve core (2) disposed in the pressure holding valve sleeve (1). One end of the pressure holding valve sleeve (1) is provided with a first spring (11). The end of the pressure holding valve sleeve (1) away from the first spring (11) is provided with a metering fuel inlet and a first fuel window. The pressure holding valve core (2) moves axially along the pressure holding valve sleeve (1) under the combined action of the first spring (11) and the metering fuel pressure to control the opening of the first fuel window. Locking valve (3) is provided with a second oil passage window and a metering fuel outlet. The second oil passage window is connected to the first oil passage window. The end of the locking valve (3) away from the metering fuel outlet forms a low-pressure fuel chamber. A two-way sealing structure (7) is installed inside the locking valve (3) to close the low-pressure fuel chamber inlet in the first state to direct the metered fuel to the metered fuel outlet, or to close the metered fuel outlet in the second state to direct the metered fuel to the low-pressure fuel chamber inlet.

2. The fuel cut-off locking device according to claim 1, characterized in that: A slider (8) is slidably connected inside the locking valve (3). The slider (8) is connected to the bidirectional sealing structure (7). A second spring (5) is provided inside the locking valve (3) to support the bidirectional sealing structure (7). The side of the slider (8) away from the bidirectional sealing structure (7) is used to bear the force of the control oil pressure, so that the slider (8) and the bidirectional sealing structure (7) reciprocate under the combined action of the control oil pressure and the second spring (5).

3. The fuel cut-off locking device according to claim 2, characterized in that: A connecting rod is provided on the slider (8), and the connecting rod is connected to the ball joint of the two-way sealing structure (7).

4. The fuel cut-off locking device according to claim 2, characterized in that: The fuel cut-off locking device also includes a solenoid valve (9). The input end of the solenoid valve (9) is connected to high-pressure fuel and low-pressure fuel respectively. The output end of the solenoid valve (9) is used to select one of the output high-pressure fuel or low-pressure fuel as the control oil pressure to drive the slider (8).

5. The fuel cut-off locking device according to claim 1, characterized in that: A third spring (6) is provided in the low-pressure fuel chamber. A sealing ball is provided at the end of the third spring (6). Under the combined action of the force of the third spring (6) and the metering fuel pressure, the sealing ball approaches or moves away from the low-pressure fuel chamber inlet to close or open the low-pressure fuel chamber inlet.

6. The fuel cut-off locking device according to claim 5, characterized in that: A positioning boss is provided in the low-pressure fuel chamber. The third spring (6) is sleeved on the positioning boss. A support seat is provided at the end of the third spring (6) away from the positioning boss. The sealing ball is embedded in the support seat.

7. The fuel cut-off locking device according to claim 1, characterized in that: The two-way sealing structure (7) includes a sealing block, and sealing elements (4) are provided on both sides of the sealing block.

8. The fuel cut-off locking device according to claim 1, characterized in that: The portion of the pressure-holding valve sleeve (1) containing the first spring (11) forms the first spring cavity. The first spring cavity is connected to the low-pressure fuel, so that the low-pressure fuel pressure and the elastic force of the first spring (11) work together on the pressure-holding valve body to balance the pressure of the metered fuel.

9. The fuel cut-off locking device according to claim 8, characterized in that: An intermediate cavity is formed between the pressure holding valve core (2) and the pressure holding valve sleeve (1). The intermediate cavity is used to introduce high-pressure fuel, so that the high-pressure fuel enters the first spring cavity through the gap between the pressure holding valve core (2) and the pressure holding valve sleeve (1).

10. The fuel cut-off locking device according to claim 9, characterized in that: The first spring cavity is provided with a limiting post, which is used to support the end of the pressure holding valve core (2) to limit the stroke of the pressure holding valve core (2).

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