Dual-control aircraft parking brake control valve with power-off hold function and control method

Abstract

The application belongs to the field of mechanical hydraulic pressure and relates to a double-control type airplane parking brake control valve with power-off keeping function and a control method. The control valve comprises a first pilot valve, a second pilot valve, a spool valve stage and a shell. The first pilot valve and the second pilot valve are installed on the upper end of the shell. The spool valve stage is installed on the lower end of the shell. The spool valve stage comprises a piston, a valve core, a valve sleeve, a spring, a left end cover and a right end cover. The valve sleeve is fixed on the shell through the left and right end covers at both ends. The spring is arranged between the right end of the valve core and the right end cover. The piston is arranged between the left end of the valve core and the left end cover, and the right end of the piston and the left end of the valve core are always in abutting state. When the airplane is in power-on or power-off state, the brake control valve can be used to realize hydraulic parking brake, and it is not necessary to use air source to realize pneumatic brake in power-off state. The working energy of the brake system is unified, and the brake control equipment is reduced. The brake control valve switches the working state after short-time power supply and keeps in power-off state, and it is not necessary to continuously supply power, so that the power consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of mechanical hydraulic, and particularly relates to a double-control type airplane parking brake control valve with power-off keeping function and a control method. BACKGROUND

[0002] There are two use scenarios for airplane parking brake, one is long-term parking in a hangar, in which the airplane is in power-off state, and the traditional way is to use a pneumatic brake to limit the airplane from sliding, and the reason for using the pneumatic brake is that the hangar parking brake needs to have the power-off keeping function, and the other is taxiing to the take-off line before take-off, in which the airplane is in power-on state, and the hydraulic brake is usually used to brake the airplane to stop, so the airplane parking brake needs to rely on both pneumatic and hydraulic energy and equipment.

[0003] In order to unify the brake energy, reduce the brake control equipment, and improve the reliability of the brake system, a parking brake control valve relying only on hydraulic energy is designed, which can meet the functions of long-term parking in a hangar and stopping on a take-off line, and the key requirement is that the parking brake valve can realize hydraulic braking function in both power-on and power-off situations, that is, it has the power-off keeping function. By designing a two-position parking brake control valve with a double-control type pilot valve, different working positions are started under different power-on forms of the pilot valve, the pressure relief function is realized, and the working position is kept in power-off. SUMMARY

[0004] The present application provides a double-control type airplane parking brake control valve with power-off keeping function and a control method, which can realize hydraulic parking brake when the airplane is in power-on or power-off state, without using pneumatic brake in power-off state, unifying the working energy of the brake system, and reducing the brake control equipment. The brake control valve switches the working state after short power supply and keeps it in power-off state, without continuous power supply, thereby reducing power consumption.

[0005] The technical scheme of the present application is as follows: the present application provides a double-control type airplane parking brake control valve with power-off keeping function, which comprises a first pilot valve, a second pilot valve, a spool valve stage, and a housing.

[0006] The first pilot valve and the second pilot valve are installed on the upper end of the housing, and the spool valve stage is installed on the lower end of the housing.

[0007] The slide valve stage comprises a piston, a valve core, a valve sleeve, a spring, a left end cover and a right end cover; the piston and the valve core are installed in the inner cavity of the valve sleeve; the valve sleeve is fixed on the shell through the left and right end covers at both ends; the spring is arranged between the right end of the valve core and the right end cover; the piston is arranged between the left end of the valve core and the left end cover, and the right end of the piston and the left end of the valve core are always in abutting state; the diameter of the left end of the piston is smaller than the diameter of the right end of the valve core; the valve core is provided with a first annular boss and a second annular boss on the periphery; the valve sleeve is sequentially provided with a left piston cavity oil port, a first oil return port, an oil inlet port, a load port, a second oil return port and a right valve core cavity oil port from left to right;

[0008] The shell is provided with an oil inlet port J, and the oil inlet port is divided into two paths, one of which is connected to the input end of the first pilot valve, and the other of which is connected to the oil inlet port of the slide valve stage; the output end of the first pilot valve is in communication with the left piston cavity oil port of the slide valve stage; the output end of the second pilot valve is in communication with the right valve core cavity oil port; the input end of the second pilot valve is in communication with the load port of the slide valve stage; the shell is also provided with an oil return port H, which is in communication with the oil return end of the first pilot valve, the oil return end of the second pilot valve, the first oil return port of the slide valve stage and the second oil return port of the slide valve stage respectively; the load port S on the shell is in communication with the load port of the slide valve stage, and is used for outputting brake pressure.

[0009] Further, the first pilot valve and the second pilot valve are the same in structure, comprising an electromagnet, a steel ball, an upper valve seat, a lower valve seat and a top rod; one end of the top rod is controlled by the electromagnet, and the other end is in abutting state with the steel ball; the steel ball is arranged between the upper valve seat and the lower valve seat; the steel ball realizes on-off control of the valve under the action of the top rod.

[0010] Further, V-shaped flow channels are formed in the left end cover and the right end cover, and the V-shaped flow channels realize the conduction between the left piston cavity oil port and the left piston cavity of the valve sleeve and the conduction between the right valve core cavity oil port and the right valve core cavity of the valve sleeve respectively.

[0011] Further, the end contact end faces of the piston and the valve core are provided with spherical structures.

[0012] Further, the piston is arranged in a piston seat, and the piston seat is fixed in the shell.

[0013] Further, a filter screen is arranged at the oil inlet port of the input end of the first pilot valve.

[0014] Another aspect of the present application also provides a control method of the double-control type airplane parking brake control valve with power-off holding function.

[0015] Working mode A: when the first pilot valve and the second pilot valve are not powered, the load port S is in communication with the oil inlet port J, the load port outputs brake pressure, and the parking brake control valve is in pressure-on state;

[0016] Working mode B: when the first pilot valve is not powered, the second pilot valve is powered, the load port S is communicated with the oil return port H, the load port has no pressure output, the parking brake control valve is in a pressure relief state, and when the second pilot valve is powered off, the load port S is still communicated with the oil return port H, and the parking brake control valve remains in the pressure relief state, that is, the second pilot valve controls the pressure relief function, and the powered pressure relief and the powered-off keeping;

[0017] Working mode C: when the first pilot valve is powered, the second pilot valve is not powered, the load port S is communicated with the oil inlet port J, the load port outputs brake pressure, the parking brake control valve is in a pressure supply state, and when the first pilot valve is powered off, the load port S is still communicated with the oil inlet port J, and the parking brake control valve remains in the pressure supply state, that is, the first pilot valve controls the pressure supply function, and the powered pressure supply and the powered-off keeping.

[0018] Further, the specific control method further comprises: after re-pressurization, being placed in a parking brake working state:

[0019] After the aircraft oil source is depressurized, the brake control valve has not been pressurized, and there is no hydraulic pressure in the interior, the valve core and the piston are placed on the left side under the action of the spring elastic force, at this time, the oil inlet J is communicated with the load port S, after re-pressurization, under the action of the oil inlet pressure, the steel ball at the first heavy pilot valve contacts the upper valve seat, and cannot block the oil inlet hole of the lower valve seat, the oil inlet J oil liquid passes through the bracket of the first heavy pilot valve to the left piston cavity oil port, the oil inlet J oil liquid passes to the load port S and the oil inlet of the lower valve seat of the second heavy pilot valve at the same time, the steel ball at the second heavy pilot valve also contacts the upper valve seat, and cannot block the oil inlet hole of the lower valve seat, the oil inlet J oil liquid passes through the bracket of the second heavy pilot valve to the right valve core cavity oil port, because the left side end surface area of the piston is smaller than the right side end surface area of the valve core, the left force acting on the valve core and the piston is greater than the right force, the valve core remains on the left side, the brake control valve keeps the oil inlet J communicated with the load port S, and the output brake pressure is the oil inlet pressure, that is, when the aircraft oil source is depressurized and re-oiled, the brake control valve places the aircraft in a parking brake working state.

[0020] In the second heavy pilot valve is powered and the power is cut off, and is placed in a parking brake working state:

[0021] The second heavy pilot valve is powered (continuous power for a period of time), and when powered, the second heavy electromagnet drives the top rod to move downward, pushing the steel ball to block the oil inlet hole of the lower spool seat, and no longer in contact with the upper spool seat. The oil in the right control chamber of the valve core passes through the oil return port H through the pressure relief hole of the upper spool seat of the second heavy pilot valve, and the pressure in the right control chamber of the valve core is reduced to the oil return pressure. The pressure in the left control chamber of the piston is still the oil inlet pressure, and the pressure difference between the two sides of the valve core and the piston drives the valve core and the piston to move to the right. The load port S is no longer communicated with the oil inlet port J, and the load port S is communicated with the oil return port H to release pressure, and the output pressure is the oil return pressure, and the aircraft is in a non-stop working state. After the second heavy pilot valve is powered off, the oil in the right control chamber of the valve core still passes through the oil return port H through the pressure relief hole of the upper spool seat of the second heavy pilot valve, and the pressure in the left control chamber of the piston is still the oil inlet pressure. The valve core and the piston remain in the right position, the load port S remains communicated with the oil return port H to release pressure, and the output pressure is the oil return pressure, that is, the second heavy pilot valve is powered (continuous power for a period of time) and the brake control valve is powered off. The aircraft is in a non-stop working state.

[0022] After the first heavy pilot valve is powered and powered off, it is placed in a stop brake working state:

[0023] The first heavy pilot valve is powered (continuous power for a period of time), and when powered, the first heavy electromagnet drives the top rod to move downward, pushing the steel ball to block the oil inlet hole of the lower spool seat. The oil in the left control chamber of the piston passes through the pressure relief hole of the upper spool seat of the first heavy pilot valve to the oil return port H, and the pressure in the left control chamber of the piston is reduced to the oil return pressure. The pressure in the right control chamber of the valve core is still the oil return pressure, and the valve core and the piston are driven to move to the left under the action of the spring force on the right side of the valve core. The oil inlet port J is communicated with the load port S, and the output brake pressure is the oil inlet pressure. At the same time, the oil inlet port J oil passes through the oil inlet port of the lower spool seat of the second heavy pilot valve, the steel ball at the second heavy pilot valve contacts the upper spool seat, cannot block the oil inlet hole of the lower spool seat, and the oil inlet port J oil passes through the right valve core cavity oil port. The pressure in the right control chamber of the valve core is increased to the oil inlet pressure, the pressure in the left control chamber of the piston is still the oil return pressure, the valve core remains in the left position, the oil inlet port J remains communicated with the load port S, and the output brake pressure is the oil inlet pressure. The aircraft is in a stop brake working state. After the first heavy pilot valve is powered off, the steel ball at the first heavy pilot valve contacts the upper spool seat under the action of the oil inlet pressure, cannot block the oil inlet hole of the lower spool seat, and only the oil inlet port J oil passes through the support of the first heavy pilot valve to the left piston cavity oil port. The pressure in the right control chamber of the valve core is still the oil inlet pressure, the left side of the piston is smaller than the right side of the valve core, the force acting on the valve core and the piston to the left is greater than the force acting to the right, the valve core remains in the left position, the brake control valve remains communicated with the oil inlet port J and the load port S, and the output brake pressure is the oil inlet pressure. That is, after the first heavy pilot valve is powered and powered off (continuous power for a period of time), the brake control valve makes the aircraft in a stop brake working state.

[0024] Technical effects: Apply hydraulic brake braking to the scene of aircraft taxiway parking and long-term hangar parking, unify the brake system working energy, reduce the brake control equipment; only need to power on when switching working position, keep the working position after power off, no need to continuous power supply, reduce the power consumption, at the same time, the working form of power off keeping reduces the dependence on brake system power stability, improves the brake system safety. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the structural schematic diagram of the present application;

[0026] Figure 2 is the working process schematic diagram of the present application;

[0027] Wherein, 1 is the first heavy pilot valve, 2 is the second heavy pilot valve, 3 is the first heavy electromagnet, 4 is the top rod, 5 is the upper valve seat, 6 is the steel ball, 7 is the bracket, 8 is the lower valve seat, 9 is the right end cover, 10 is the valve core, 11 is the spring, 12 is the valve sleeve, 13 is the piston seat, 14 is the piston, 15 is the left end cover, 16 is the shell, 17 is the filter screen, 18 is the second heavy electromagnet; J: oil inlet; S: load port; H: oil return port. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the present application is described in detail below in combination with the drawings or specific implementation cases. It should be noted that some (but not all) of the disclosed examples are shown in the drawings. In fact, many different examples can be described and these examples should not be understood as being limited to the examples set forth herein. On the contrary, these examples are described so that the positive effects of the present application are more embodied, and the details not described herein are regarded as known or conventional technical means in the art.

[0029] Referring to the accompanying Figure 1 , referring to the accompanying Figure 1 , the present application specifically designs a double-control type aircraft parking brake control valve with power-off keeping function, which comprises a first heavy pilot valve 1, a second heavy pilot valve 2, a first heavy electromagnet 3, a top rod 4, an upper valve seat 5, a steel ball 6, a bracket 7, a lower valve seat 8, a right end cover 9, a valve core 10, a spring 11, a valve sleeve 12, a piston seat 13, a piston 14, a left end cover 15, a shell 16, a filter screen 17, and a second heavy electromagnet 18. The first heavy electromagnet 3, the top rod 4, the upper valve seat 5, the steel ball 6, the bracket 7, and the lower valve seat 8 together form a first pilot valve. The second heavy electromagnet 18, the top rod 4, the upper valve seat 5, the steel ball 6, the bracket 7, and the lower valve seat 8 together form a second pilot valve. The structures of the two pilot valves are completely the same.

[0030] In addition, the right end cover 9, valve core 10, spring 11, valve sleeve 12, piston seat 13, piston 14, left end cover 15, and housing 16 together form the spool valve stage of the control valve.

[0031] Based on the working principle of aircraft braking systems, the specific control process during implementation includes:

[0032] 1) When the output pressure of the brake control valve is equal to the inlet oil pressure, it is in the pressurized state, and the brake system is in the stop brake working state;

[0033] 2) When the output pressure of the brake control valve is the return oil pressure, it is in a depressurization state, and the brake system is in a state of being released from shutdown.

[0034] To better illustrate the present invention, the following description is provided in conjunction with the accompanying drawings. Figure 1 and attached Figure 2 Detailed explanation.

[0035] a) After repressurization, place the machine in the shutdown brake operating state.

[0036] After the aircraft fuel source is depressurized, the brake control valve is not yet pressurized and has no internal hydraulic pressure. Valve core 10 and piston 14 are positioned to the left under the force of spring 11. At this time, the fuel inlet J communicates with the load port S, as shown in the attached diagram. Figure 2 As shown. After repressurization, under the action of the inlet oil pressure, the steel ball 6 at the first heavy-duty pilot valve 1 contacts the upper valve seat 5, and cannot block the oil inlet of the lower valve seat 8. The oil inlet J flows through the bracket 7 of the first heavy-duty pilot valve 1 to the oil port of the left piston chamber. The oil inlet J flows to the load port S and simultaneously to the oil inlet of the lower valve seat 8 of the second heavy-duty pilot valve 2. The steel ball 6 at the second heavy-duty pilot valve 2 also contacts the upper valve seat 5, and cannot block the oil inlet of the lower valve seat 8. Oil J flows through the bracket 7 of the second pilot valve 2 to the oil port of the right valve core cavity. Because the area of ​​the left end face of piston 14 is smaller than the area of ​​the right end face of valve core 10, the force acting on the valve core 10 and piston 14 to the left is greater than the force acting to the right. Valve core 10 remains in the left position, and the brake control valve keeps the oil inlet J connected to the load port S. The output brake pressure is the oil inlet pressure. That is, when the aircraft oil source is depressurized and re-supplyed, the brake control valve puts the aircraft into the stop brake working state.

[0037] b) After the second pilot valve 2 is energized and de-energized, it is placed in the state of being released from shutdown operation.

[0038] The second heavy pilot valve 2 is powered (continuous power 3s), and when powered, the second heavy electromagnet 18 drives the top rod 4 to move downward, pushing the steel ball 6 to block the oil inlet hole of the lower valve seat 8, and no longer contacting the upper valve seat 5. The oil in the right control chamber of the valve core 10 passes through the oil return hole of the upper valve seat 5 of the second heavy pilot valve 2 to the oil return port H, and the pressure in the right control chamber of the valve core 10 is reduced to the oil return pressure. The pressure in the left control chamber of the piston 14 is still the oil inlet pressure, and the pressure difference between the two sides of the valve core 10 and the piston 14 drives them to move to the right. The load port S is no longer communicated with the oil inlet port J, and the load port S is communicated with the oil return port H to release pressure, and the output pressure is the oil return pressure, as shown in the accompanying drawings, and the aircraft is in the release parking working state. After the second heavy pilot valve 2 is powered off, the oil in the right control chamber of the valve core 10 still passes through the oil return hole of the upper valve seat 5 of the second heavy pilot valve 2 to the oil return port H, and the pressure in the left control chamber of the piston 14 is still the oil inlet pressure. The valve core 10 and the piston 14 remain in the right position, the load port S remains communicated with the oil return port H to release pressure, and the output pressure is the oil return pressure. That is, after the second heavy pilot valve 2 is powered (continuous power 3s) and the power is cut off, the brake control valve makes the aircraft in the release parking working state. Figure 1

[0039] c) The first heavy pilot valve 1 is powered and cut off after parking in the brake working state

[0040] The first heavy pilot valve 1 is powered (continuous power 3s), and when powered, the first heavy electromagnet 3 drives the top rod 4 to move downward, pushing the steel ball 3 to block the oil inlet hole of the lower valve seat 5. The oil in the left control chamber of the piston 14 passes through the oil return hole of the upper valve seat 5 of the first heavy pilot valve 1 to the oil return port H, and the pressure in the left control chamber of the piston 14 is reduced to the oil return pressure. The pressure in the right control chamber of the valve core 10 is still the oil return pressure, and under the action of the spring 11 on the right side of the valve core 10, the valve core 10 and the piston 14 are driven to move to the left. The oil inlet port J is communicated with the load port S, and the output brake pressure is the oil inlet pressure. At the same time, the oil inlet port J oil passes through the oil inlet port of the lower valve seat 8 of the second heavy pilot valve 2, the steel ball 6 at the second heavy pilot valve 2 contacts the upper valve seat 5 and cannot block the oil inlet hole of the lower valve seat 8, the oil inlet port J oil passes through the right valve core chamber oil port, the pressure in the right control chamber of the valve core 10 is increased to the oil inlet pressure, the pressure in the left control chamber of the piston 14 is still the oil return pressure, the valve core 10 remains in the left position, the oil inlet port J remains communicated with the load port S, and the output brake pressure is the oil inlet pressure, as shown in the accompanying drawings, and the aircraft is in the parking working state. Figure 2 ​As shown, the aircraft is in the parking brake working state; after the first heavy pilot valve 1 is powered off, under the action of the inlet oil pressure, the steel ball 6 at the first heavy pilot valve 1 contacts the upper valve seat 5, cannot block the inlet oil hole of the lower valve seat 8, and only the J oil liquid is communicated to the left piston cavity oil port through the support 7 of the first heavy pilot valve 1, the right side control cavity pressure of the valve core 10 is still the inlet oil pressure, because the left side end surface area of the piston 14 is smaller than the right side end surface area of the valve core 10, the left acting force on the valve core 10 and the piston 14 is greater than the right acting force, the valve core 10 keeps the left side position, the brake control valve keeps the inlet J communicated with the load S, and the output brake pressure is the inlet oil pressure, that is, the first heavy pilot valve 1 is powered on (continuous power supply for 3s) and powered off, and the brake control valve makes the aircraft in the parking brake working state.

[0041] The above specific embodiments or cases are only used to explain the technical solutions of the present application, and are not limited to the present application, and the parts not described in detail are regarded as conventional technical means or common knowledge in the art; It can be understood by those skilled in the art that: based on the design idea of the present application, the technical solutions recorded in the foregoing embodiments can be adaptively modified, or part or all of the technical features can be replaced by equivalents, and these modified, equivalent, adaptive improved technical solutions do not deviate from the technical essence of the present application, and should be covered within the protection scope of the present application.

Claims

1. A dual-control aircraft parking brake control valve with power-off retention function, characterized in that, The control valve includes: a first pilot valve, a second pilot valve, a spool valve stage, and a housing; The first pilot valve and the second pilot valve are installed at the upper end of the housing; the slide valve stage is installed at the lower end of the housing; The spool valve stage includes a piston, a valve core, a valve sleeve, a spring, a left end cap, and a right end cap; the piston and valve core are installed in the inner cavity of the valve sleeve; both ends of the valve sleeve are fixed to the housing by the left and right end caps respectively; a spring is provided between the right end of the valve core and the right end cap; a piston is provided between the left end of the valve core and the left end cap, and the right end of the piston and the left end of the valve core are always in abutting state; the diameter of the left end of the piston is smaller than the diameter of the right end of the valve core; a first annular boss and a second annular boss are provided around the valve core; the valve sleeve is provided with a left piston cavity oil port, a first return oil port, an inlet oil port, a load port, a second return oil port, and a right valve core cavity oil port in sequence from left to right; The housing has an oil inlet J, and the oil inlet path is divided into two paths, one of which is connected to the input end of the first pilot valve, and the other is connected to the oil inlet of the spool valve stage. The output end of the first pilot valve is connected to the oil port of the left piston chamber of the spool valve stage. The output end of the second pilot valve is connected to the oil port of the right valve core chamber. The input end of the second pilot valve is connected to the load port of the spool valve stage. The housing also has a return oil port H, which is connected to the return oil end of the first pilot valve, the return oil end of the second pilot valve, the first return oil port of the spool valve stage, and the second return oil port of the spool valve stage. The load port S on the housing is connected to the load port of the spool valve stage and is used to output brake pressure.

2. The dual-control aircraft parking brake control valve with power-off retention function as described in claim 1, characterized in that, The first pilot valve and the second pilot valve have the same structure, including an electromagnet, a steel ball, an upper valve seat, a lower valve seat, and a push rod; one end of the push rod is controlled by the electromagnet, and the other end abuts against the steel ball; the steel ball is placed between the upper valve seat and the lower valve seat; the steel ball, under the action of the push rod, realizes the on / off control of the valve.

3. The dual-control aircraft parking brake control valve with power-off retention function as described in claim 1, characterized in that, Both the left and right end caps are provided with V-shaped flow channels to enable the oil port of the left piston chamber of the valve sleeve to communicate with the left piston chamber, and the oil port of the right valve core chamber of the valve sleeve to communicate with the right valve core chamber, respectively.

4. A dual-control aircraft parking brake control valve with power-off retention function as described in claim 1, characterized in that, The end face of the piston that contacts the valve core is configured as a spherical structure.

5. A dual-control aircraft parking brake control valve with power-off retention function as described in claim 4, characterized in that, The piston is disposed within a piston seat, and the piston seat is fixed within the housing.

6. A dual-control aircraft parking brake control valve with power-off retention function as described in claim 1, characterized in that, A filter screen is installed at the oil inlet of the first pilot valve input end.

7. A control method for a dual-control aircraft parking brake control valve with power-off retention function as described in any one of claims 1 to 6, characterized in that, include: Operating mode A: When neither the first pilot valve nor the second pilot valve is energized, the load port S is connected to the oil inlet port J, the load port outputs brake pressure, and the parking brake control valve is in the pressurized state. Operating mode B: When the first pilot valve is not energized and the second pilot valve is energized, the load port S is connected to the return port H, there is no pressure output at the load port, and the parking brake control valve is in a depressurization state. When the second pilot valve is de-energized, the load port S and the return port H are still connected, and the parking brake control valve remains in a depressurization state. That is, the second pilot valve controls the depressurization function, depressurizing when energized and maintaining when de-energized. Operating mode C: When the first pilot valve is energized and the second pilot valve is not energized, the load port S is connected to the oil inlet J, the load port outputs brake pressure, and the parking brake control valve is in the pressurized state. When the first pilot valve is de-energized, the load port S and the oil inlet J are still connected, and the parking brake control valve maintains the pressurized state. That is, the first pilot valve controls the pressurized function, pressurizing when energized and maintaining the pressurized state when de-energized.

8. The control method for the dual-control aircraft parking brake control valve with power-off retention function as described in claim 7, characterized in that, After repressurization, place the machine in the shutdown brake operating state: After the aircraft fuel source is depressurized, the brake control valve is not yet pressurized, and there is no internal hydraulic pressure. The valve core and piston are positioned to the left under the spring force. At this time, the fuel inlet J is connected to the load port S. After repressurization, under the fuel inlet pressure, the steel ball at the first pilot valve contacts the upper valve seat, preventing it from blocking the fuel inlet of the lower valve seat. Fuel from fuel inlet J flows through the bracket of the first pilot valve to the left piston chamber port. The oil flows to the load port S and simultaneously to the oil inlet of the lower valve seat of the second pilot valve. The steel ball at the second pilot valve is also in contact with the upper valve seat and cannot block the oil inlet of the lower valve seat. The oil inlet J flows through the bracket of the second pilot valve to the oil port of the right valve core cavity. Because the area of ​​the left end face of the piston is smaller than the area of ​​the right end face of the valve core, the force acting on the valve core and piston to the left is greater than the force acting to the right. The valve core remains in the left position, and the brake control valve keeps the oil inlet J connected to the load port S. The output brake pressure is the oil inlet pressure, that is, when the aircraft oil source is depressurized and re-supplyed, the brake control valve puts the aircraft into the stop brake working state.

9. The control method for the dual-control aircraft parking brake control valve with power-off retention function as described in claim 7, characterized in that, After the second pilot valve is energized and de-energized, the machine is placed in the off-stop state: When the second pilot valve is energized, the second electromagnet drives the push rod downwards, pushing the steel ball to block the oil inlet of the lower valve seat, thus preventing it from contacting the upper valve seat. The oil in the control chamber on the right side of the valve core flows through the pressure relief hole of the upper valve seat of the second pilot valve to the return port H. The pressure in the control chamber on the right side of the valve core decreases to the return pressure, while the pressure in the control chamber on the left side of the piston remains the inlet pressure. A pressure difference exists between the valve core and the piston, driving them to move to the right. The load port S is no longer connected to the inlet port J. S is connected to the return oil port H for pressure relief, and the output pressure is the return oil pressure, putting the aircraft in the de-stopped operation state; after the second pilot valve is energized and de-energized, the oil in the control chamber on the right side of the valve core still flows to the return oil port H through the pressure relief hole of the upper valve seat of the second pilot valve, and the pressure in the control chamber on the left side of the piston is still the inlet oil pressure. The valve core and piston remain in the right position, and the load port S remains connected to the return oil port H for pressure relief, with the output pressure being the return oil pressure. That is, after the second pilot valve is energized and de-energized, the brake control valve puts the aircraft in the de-stopped operation state.

10. The control method for the dual-control aircraft parking brake control valve with power-off retention function as described in claim 7, characterized in that, After the first pilot valve is energized and de-energized, the machine is placed in the shutdown brake operating state: When the first pilot valve is energized, the first electromagnet drives the push rod downwards, pushing the steel ball to block the oil inlet of the lower valve seat. Oil in the control chamber on the left side of the piston flows through the pressure relief hole of the upper valve seat of the first pilot valve to the return port H, reducing the pressure in the control chamber on the left side of the piston to the return pressure. The pressure in the control chamber on the right side of the valve core remains the return pressure. Under the spring force on the right side of the valve core, the valve core and piston move to the left, connecting the oil inlet J to the load port S. The output braking pressure is the inlet pressure. Simultaneously, oil inlet J flows to the oil inlet of the lower valve seat of the second pilot valve. The steel ball at the second pilot valve contacts the upper valve seat and cannot block the oil inlet of the lower valve seat. Oil inlet J flows to the oil port of the right valve core cavity, increasing the pressure in the control chamber on the right side of the valve core to the inlet pressure. The pressure in the control chamber on the left side of the piston remains the return pressure. When the valve core remains in the left position, the oil inlet J remains connected to the load port S, and the output brake pressure is the oil inlet pressure, the aircraft is in the stop brake working state; after the first pilot valve is de-energized, under the action of the oil inlet pressure, the steel ball at the first pilot valve contacts the upper valve seat, and cannot block the oil inlet hole of the lower valve seat. The oil inlet J flows through the bracket of the first pilot valve to the oil port of the left piston chamber. The pressure in the control chamber on the right side of the valve core is still the oil inlet pressure. Because the area of ​​the left end face of the piston is smaller than the area of ​​the right end face of the valve core, the force acting on the valve core and piston to the left is greater than the force acting to the right. The valve core remains in the left position, the brake control valve keeps the oil inlet J connected to the load port S, and the output brake pressure is the oil inlet pressure. That is, after the first pilot valve is energized and de-energized, the brake control valve puts the aircraft in the stop brake working state.

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