Double-control type airplane parking brake control valve with power-off maintaining function and control method

Abstract

The invention belongs to the field of mechanical hydraulic pressure, and relates to a double-control type aircraft parking brake control valve with a power-off maintaining function and a control method.The control valve comprises a first pilot valve, a second pilot valve, a slide valve stage and a shell; the first pilot valve and the second pilot valve are mounted at the upper end of the shell; the slide valve stage is mounted at the lower end of the shell; the slide valve stage comprises a piston, a valve core, a valve sleeve, a spring, a left end cover and a right end cover; two ends of the valve sleeve are respectively fixed on the shell through left and right end covers; a spring is arranged between the right end of the valve core and the right end cover; a piston is arranged between the left end of the valve element and the left end cover. The right end of the piston abuts against the left end of the valve element all the time. When an airplane is powered on / off, hydraulic stopping and braking can be achieved through the brake control valve, pneumatic braking through an air source during power failure is not needed, working energy of a brake system is unified, and brake control equipment is reduced; the brake control valve switches the working state after short-time power supply and keeps the working state after power failure, continuous power supply is not needed, and power consumption is reduced.

Description

Technical Field

[0001] The invention belongs to the field of mechanical hydraulics, and in particular relates to a dual-control aircraft parking brake control valve with a power-off holding function and a control method. Background Art

[0002] There are usually two usage scenarios for aircraft parking brakes. One is when the aircraft is parked in a hangar for a long time and is in a power-off state. The traditional method is to use pneumatic brakes to brake the wheels and limit the aircraft's slippage. The reason for using pneumatic brakes is that the hangar parking brakes need to be powered off to maintain the braking function. The second is when taxiing to the take-off line before takeoff, the aircraft is in a powered-on state, and hydraulic brakes are usually used to brake the wheels to achieve parking. Therefore, the aircraft parking brakes need to rely on both air pressure 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 that only relies on hydraulic energy is designed to meet the functions of long-term parking in the hangar and parking brake on the takeoff line. The key requirement is that the parking brake valve can realize the hydraulic brake function in both power-on and power-off situations, that is, it has a power-off holding function. By designing a two-position parking brake control valve with a double-control pilot valve, different working positions are started under different pilot valve power-on forms, realizing the pressure-on and pressure-release functions, and the working position is maintained when the power is off. Summary of the invention

[0004] Purpose of the invention: To propose a dual-control aircraft parking brake control valve with a power-off holding function and a control method. When the aircraft is in a power-on / power-off state, the brake control valve can be used to implement hydraulic parking brakes. There is no need to use an air source for pneumatic braking when the power is off, and the working energy of the brake system is unified, reducing the number of brake control devices. The brake control valve switches the working state after a short power supply and maintains it after a power outage. There is no need for continuous power supply, which reduces power consumption.

[0005] Technical solution: On one hand, the present invention proposes a dual-control aircraft parking brake control valve with a power-off holding function, the control valve comprising: a first pilot valve, a second pilot valve, a sliding valve stage, and a housing;

[0006] 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;

[0007] The sliding valve stage includes 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 two ends of the valve sleeve are fixed to the housing through the left and right end covers respectively; a spring is arranged between the right end of the valve core and the right end cover; a 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 a state of abutment; the diameter of the left end of the piston is smaller than the diameter of the right end of the valve core; the periphery of the valve core is provided with a first annular boss and a second annular boss; the valve sleeve is 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 in sequence from the left;

[0008] An oil inlet J is provided on the shell, and the oil inlet circuit is divided into two circuits, 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 sliding valve stage; the output end of the first pilot valve is connected to the left piston chamber oil port of the sliding valve stage; the output end of the second pilot valve is connected to the right valve core chamber oil port; the second pilot valve input end is connected to the load port of the sliding valve stage; an oil return port H is also provided on the shell, and the oil return port H is respectively connected to 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 sliding valve stage, and the second oil return port of the sliding valve stage; the load port S on the shell is connected to the load port of the sliding valve stage for outputting brake pressure.

[0009] Furthermore, 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 is against the steel ball; the steel ball is placed between the upper valve seat and the lower valve seat; under the action of the push rod, the steel ball realizes the on-off control of the valve.

[0010] Furthermore, the left end cover and the right end cover are both provided with V-shaped flow channels, which respectively realize the communication between the left piston chamber oil port of the valve sleeve and the left piston chamber, and the communication between the right valve core chamber oil port of the valve sleeve and the right valve core chamber.

[0011] Furthermore, the contact end surface between the piston and the valve core end is configured as a spherical structure.

[0012] Furthermore, the piston is arranged in a piston seat, and the piston seat is fixed in the housing.

[0013] Furthermore, a filter is provided at the oil inlet of the input end of the first pilot valve.

[0014] On the other hand, the present invention also provides a control method for the dual-control aircraft parking brake control valve with power-off holding function as described above;

[0015] Working mode A: When both the first pilot valve and the second pilot valve are not energized, the load port S is connected to the oil inlet J, the load port outputs the brake pressure, and the parking brake control valve is in the pressure-passing state;

[0016] Working 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 oil return port H, there is no pressure output at the load port, and the parking brake control valve is in a pressure relief state. When the second pilot valve is then de-energized, the load port S is still connected to the oil return port H, and the parking brake control valve remains in a pressure relief state, that is, the second pilot valve controls the pressure relief function, which is energized to release pressure and de-energized to maintain pressure;

[0017] Working 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 a pressure-through state. When the first pilot valve is then de-energized, the load port S is still connected to the oil inlet J, and the parking brake control valve maintains a pressure-through state, that is, the first pilot valve controls the pressure-through function, and the pressure is on when energized and maintained when de-energized.

[0018] Furthermore, the specific control method also includes: placing the engine in a parking brake working state after re-supplying pressure:

[0019] After the aircraft oil source is depressurized, the brake control valve has not yet been supplied with pressure, and there is no liquid pressure inside. The valve core and the piston are placed on the left side under the action of the spring force. At this time, the oil inlet J is connected to the load port S. After the pressure is re-supplied, under the action of the oil inlet pressure, the steel ball at the first electric pilot valve contacts the upper valve seat and cannot block the oil inlet hole of the lower valve seat. The oil at the oil inlet J flows to the left piston chamber oil port through the bracket of the first pilot valve. The oil at the oil inlet J flows to the load port S and at the same time to the oil inlet of the lower valve seat of the second pilot valve. The steel ball is also in contact with the upper valve seat and cannot block the oil inlet hole of the lower valve seat. The oil in the oil inlet J flows to the oil port of the right valve core chamber through the bracket of the second pilot valve. Because the left end surface area of ​​the piston is smaller than the right end surface area of ​​the valve core, the left force acting on the valve core and the piston is greater than the right force, and the valve core maintains the left position. The brake control valve keeps the oil inlet J communicating 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-supplied with oil, the brake control valve puts the aircraft in the parking brake working state.

[0020] After the second pilot valve is powered on and off, it is placed in the shutdown state:

[0021] The second pilot valve is energized (continuously energized for a period of time). When energized, the second electromagnet drives the push rod to move downward, pushing the steel ball to block the oil inlet hole of the lower valve seat, and no longer contacts the upper valve seat. The oil in the control chamber on the right side of the valve core flows to the return oil port H through the pressure relief hole of the upper valve seat of the second pilot valve. The pressure in the control chamber on the right side of the valve core is reduced to the return oil pressure, and the pressure in the control chamber on the left side of the piston is still the inlet oil pressure. There is a pressure difference between the pressures on both sides of the valve core and the piston, which drives the valve core and the piston to move rightward. The load port S is no longer in communication with the oil inlet port J, and the load port S It communicates with the oil return port H for pressure relief, and the output pressure is the oil return pressure, and the aircraft is in a state of releasing the shutdown; after the second pilot valve is powered on and off, the oil in the control chamber on the right side of the valve core still flows to the oil return 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 oil inlet pressure, the valve core and the piston maintain the right position, and the load port S maintains communication with the oil return port H for pressure relief, and the output pressure is the oil return pressure, that is, the brake control valve puts the aircraft in a state of releasing the shutdown after the second pilot valve is powered on (continuously powered on for a period of time) and the power is cut off.

[0022] After the first pilot valve is energized and de-energized, it is placed in the parking brake working state:

[0023] The first pilot valve is energized (continuously energized for a period of time). When energized, the first solenoid drives the push rod to move downward, pushing the steel ball to block the oil inlet hole of the lower valve seat. The oil in the control chamber on the left side of the piston passes through the pressure relief hole of the upper valve seat of the first pilot valve to the return oil port H. The pressure in the control chamber on the left side of the piston is reduced to the return oil pressure, and the pressure in the control chamber on the right side of the valve core is still the return oil pressure. Under the action of the spring force on the right side of the valve core, the valve core and the piston are driven to move left, and the oil inlet J communicates with the load port S. The output brake pressure is the oil inlet pressure. At the same time, the oil at the oil inlet J is connected 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 hole of the lower valve seat. The oil at the oil inlet J is connected to the oil port of the right valve core chamber, and the pressure in the control chamber on the right side of the valve core increases to the oil inlet pressure, and the pressure in the control chamber on the left side of the piston is still the return oil pressure. , the valve core keeps the left position, the oil inlet J keeps communicating with the load port S, the output brake pressure is the oil inlet pressure, and the aircraft is in the parking brake working state; after the first pilot valve is powered off, under the action of the oil inlet pressure, the steel ball at the first pilot valve contacts with the upper valve seat and cannot block the oil inlet hole of the lower valve seat. Only the oil from port J flows to the left piston chamber oil port through the bracket of the first pilot valve, and the pressure in the control chamber on the right side of the valve core is still the oil inlet pressure. Because the left end surface area of ​​the piston is smaller than the right end surface area of ​​the valve core, the leftward force acting on the valve core and the piston is greater than the rightward force, and the valve core keeps the left position, and the brake control valve keeps the oil inlet J communicating with the load port S, and the output brake pressure is the oil inlet pressure, that is, after the first pilot valve is powered on and off (powered on continuously for a period of time), the brake control valve puts the aircraft in the parking brake working state.

[0024] Technical effect: Hydraulic brakes are applied in scenarios of aircraft parking on the takeoff line and long-term hangar parking, which unifies the working energy of the brake system and reduces the brake control equipment; power is only required when switching working positions, and the working position is maintained after power failure, without the need for continuous power supply, reducing power consumption. At the same time, the power-off holding working mode reduces the dependence on the stability of the brake system power supply and improves the safety of the brake system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the working process of the present invention;

[0026] Among them, 1 is the first pilot valve, 2 is the second pilot valve, 3 is the first electromagnet, 4 is the push 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, and 18 is the second electromagnet; J: oil inlet; S: load port; H: oil return port. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the present invention is described in detail below in conjunction with the drawings or specific implementation cases of the specification. 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 invention are more reflected, and any parts not detailed in the text are regarded as known techniques or conventional technical means in the art.

[0028] See attached Figure 1 , see attached Figure 1 The present invention specifically designs a dual-control aircraft parking brake control valve with a power-off holding function, comprising a first pilot valve 1, a second pilot valve 2, a first electromagnet 3, a push 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 electromagnet 18; wherein the first electromagnet 3, the push rod 4, the upper valve seat 5, the steel ball 6, the bracket 7, and the lower valve seat 8 together constitute the first pilot valve; the second electromagnet 18, the push rod 4, the upper valve seat 5, the steel ball 6, the bracket 7, and the lower valve seat 8 together constitute the second pilot valve; the two pilot valves have exactly the same structure.

[0029] In addition, the right end cover 9, the valve core 10, the spring 11, the valve sleeve 12, the piston seat 13, the piston 14, the left end cover 15, and the housing 16 together constitute the slide valve stage of the control valve.

[0030] According to the working principle of the aircraft braking system, in the specific implementation process, the specific control process includes:

[0031] 1) When the output pressure of the brake control valve is equal to the oil inlet pressure, it is in the pressure-through state, and the brake system is in the parking brake working state;

[0032] 2) When the output pressure of the brake control valve is the return oil pressure, it is in the pressure relief state, and the brake system is in the shutdown release working state;

[0033] To better illustrate the present invention, the following Figure 1 and attached Figure 2 Specific instructions.

[0034] a) After re-supplying pressure, put it into parking brake working state

[0035] After the aircraft oil source is depressurized, the brake control valve has not yet been supplied with pressure, and there is no liquid pressure inside. The valve core 10 and the piston 14 are placed on the left side under the elastic force of the spring 11. At this time, the oil inlet J is connected to the load port S. Figure 2 After the pressure is re-supplied, under the action of the oil inlet pressure, the steel ball 6 at the first electric pilot valve 1 contacts the upper valve seat 5 and cannot block the oil inlet hole of the lower valve seat 8. The oil at the oil inlet J flows to the oil port of the left piston chamber through the bracket 7 of the first pilot valve 1. The oil at the oil inlet J flows to the load port S and at the same time to the oil inlet of the lower valve seat 8 of the second pilot valve 2. The steel ball 6 at the second pilot valve 2 also contacts the upper valve seat 5 and cannot block the oil inlet hole of the lower valve seat 8. The J oil flows to the right valve core chamber oil port through the bracket 7 of the second pilot valve 2. Because the left end surface area of ​​the piston 14 is smaller than the right end surface area of ​​the valve core 10, the leftward force acting on the valve core 10 and the piston 14 is greater than the rightward force, and the valve core 10 maintains the left position. The brake control valve keeps the oil inlet J communicating 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-supplied with oil, the brake control valve puts the aircraft into the parking brake working state.

[0036] b) The second pilot valve 2 is energized and de-energized to be placed in the shutdown release working state

[0037] The second pilot valve 2 is energized (continuously energized for 3s). When energized, the second electromagnet 18 drives the push 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 contacts the upper valve seat 5. The oil in the control chamber on the right side of the valve core 10 is connected to the return oil port H through the pressure relief hole of the upper valve seat 5 of the second pilot valve 2. The pressure in the control chamber on the right side of the valve core 10 is reduced to the return oil pressure, and the pressure in the control chamber on the left side of the piston 14 is still the inlet oil pressure. There is a pressure difference between the pressures acting on both sides of the valve core 10 and the piston 14, which drives the valve core 10 and the piston 14 to move rightward. The load port S is no longer in communication with the oil inlet port J, and the load port S communicates with the return oil port H to relieve pressure. The output pressure is the return oil pressure. Figure 1 As shown, the aircraft is in the state of releasing the parking state; after the second pilot valve 2 is powered on and off, the oil in the control chamber on the right side of the valve core 10 still flows to the oil return port H through the pressure relief hole of the upper valve seat 5 of the second pilot valve 2, and the pressure in the control chamber on the left side of the piston 14 is still the oil inlet pressure. The valve core 10 and the piston 14 maintain the right position, and the load port S maintains communication with the oil return port H for pressure relief, and the output pressure is the oil return pressure, that is, the second pilot valve 2 is powered on (continuously powered on for 3s) and the brake control valve is powered off to put the aircraft in the state of releasing the parking state.

[0038] c) The first pilot valve 1 is energized and de-energized to the parking brake working state

[0039] The first pilot valve 1 is energized (continuously energized for 3s). When energized, the first electromagnet 3 drives the push 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 control chamber on the left side of the piston 14 flows to the oil return port H through the pressure relief hole of the upper valve seat 5 of the first pilot valve 1. The pressure in the control chamber on the left side of the piston 14 is reduced to the oil return pressure, and the pressure in the control chamber on the right side of the valve core 10 is still the oil return pressure. Under the elastic force 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 leftward, and the oil inlet J is grooved with the load port S. The output brake pressure is the oil inlet pressure. At the same time, the oil at the oil inlet J leads to the oil inlet of the lower valve seat 8 of the second pilot valve 2. The steel ball 6 at the second pilot valve 2 contacts the upper valve seat 5 and cannot block the oil inlet hole of the lower valve seat 8. The oil at the oil inlet J leads to the oil port of the right valve core chamber. The pressure in the control chamber on the right side of the valve core 10 increases to the oil inlet pressure, and the pressure in the control chamber on the left side of the piston 14 is still the return oil pressure. The valve core 10 maintains the left position, and the oil inlet J maintains communication with the load port S. The output brake pressure is the oil inlet pressure. Figure 2As shown, the aircraft is in the parking brake working state; after the first pilot valve 1 is powered off, under the action of the oil inlet pressure, the steel ball 6 at the first pilot valve 1 contacts the upper valve seat 5 and cannot block the oil inlet hole of the lower valve seat 8. Only the oil from port J flows to the oil port of the left piston chamber through the bracket 7 of the first pilot valve 1. The pressure in the control chamber on the right side of the valve core 10 is still the oil inlet pressure. Because the left end surface area of ​​the piston 14 is smaller than the right end surface area of ​​the valve core 10, the left force acting on the valve core 10 and the piston 14 is greater than the right force, and the valve core 10 maintains the left position. The brake control valve keeps the oil inlet J communicating with the load port S, and the output brake pressure is the oil inlet pressure, that is, the first pilot valve 1 is powered on (continuously powered on for 3s) and the brake control valve puts the aircraft in the parking brake working state after the power is cut off.

[0040] The above specific implementation methods or cases are only used to explain the technical solutions of the present invention, and are not intended to limit the present application. Any parts not described in detail are deemed to be conventional technical means or common knowledge in the field. It can be understood by ordinary technicians in this field that: based on the design concept of the present application, the technical solutions recorded in the aforementioned implementation methods should be adaptively modified, or some or all of the technical features therein should be replaced by equivalents. These modifications, equivalent replacements, and adaptively improved technical solutions do not depart from the technical essence of the present invention and should all be covered within the protection scope of the present application.

Claims

1. A dual-control aircraft parking brake control valve with power-off holding function, characterized in that: The control valve comprises: a first pilot valve, a second pilot valve, a slide 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 sliding valve stage includes 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 two ends of the valve sleeve are fixed to the housing through the left and right end covers respectively; a spring is arranged between the right end of the valve core and the right end cover; a 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 a state of abutment; the diameter of the left end of the piston is smaller than the diameter of the right end of the valve core; the periphery of the valve core is provided with a first annular boss and a second annular boss; the valve sleeve is 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 in sequence from the left; An oil inlet J is provided on the shell, and the oil inlet circuit is divided into two circuits, 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 sliding valve stage; the output end of the first pilot valve is connected to the left piston chamber oil port of the sliding valve stage; the output end of the second pilot valve is connected to the right valve core chamber oil port; the second pilot valve input end is connected to the load port of the sliding valve stage; an oil return port H is also provided on the shell, and the oil return port H is respectively connected to 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 sliding valve stage, and the second oil return port of the sliding valve stage; the load port S on the shell is connected to the load port of the sliding valve stage for outputting brake pressure.

2. A dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 1, characterized in that: The first pilot valve has the same structure as the second pilot valve, 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 is against the steel ball; the steel ball is placed between the upper valve seat and the lower valve seat; under the action of the push rod, the steel ball realizes the on-off control of the valve.

3. A dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 1, characterized in that: The left end cover and the right end cover are both provided with V-shaped flow channels, which respectively realize the communication between the left piston chamber oil port of the valve sleeve and the left piston chamber, and the communication between the right valve core chamber oil port of the valve sleeve and the right valve core chamber.

4. A dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 1, characterized in that: The contact end surface of the piston and the valve core end is arranged as a spherical structure.

5. A dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 4, characterized in that: The piston is arranged in a piston seat, and the piston seat is fixed in the housing.

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

7. A control method for a dual-control aircraft parking brake control valve with a power-off holding function as claimed in any one of claims 1 to 6, characterized in that: include: Working mode A: When the first pilot valve and the second pilot valve are not energized, the load port S is connected to the oil inlet J, the load port outputs the brake pressure, and the parking brake control valve is in the pressure-passing state; Working 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 oil return port H, there is no pressure output at the load port, and the parking brake control valve is in a pressure relief state. When the second pilot valve is then de-energized, the load port S is still connected to the oil return port H, and the parking brake control valve remains in a pressure relief state, that is, the second pilot valve controls the pressure relief function, which is energized to release pressure and de-energized to maintain pressure; Working 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 a pressure-through state. When the first pilot valve is then de-energized, the load port S is still connected to the oil inlet J, and the parking brake control valve maintains a pressure-through state, that is, the first pilot valve controls the pressure-through function, and the pressure is on when energized and maintained when de-energized.

8. The control method of the dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 7, characterized in that: After re-supplied with pressure, put the machine into parking brake working state: After the aircraft oil source is depressurized, the brake control valve has not yet been supplied with pressure, and there is no liquid pressure inside. The valve core and the piston are placed on the left side under the action of the spring force. At this time, the oil inlet J is connected to the load port S, as shown in the attached figure. After the pressure is re-supplied, under the action of the oil inlet pressure, the steel ball at the first electric pilot valve contacts with the upper valve seat and cannot block the oil inlet hole of the lower valve seat. The oil at the oil inlet J flows to the left piston chamber oil port through the bracket of the first pilot valve. The oil at the oil inlet J flows to the load port S and at the same time flows to the oil inlet of the lower valve seat of the second pilot valve. The steel ball at the second pilot valve also contacts with the upper valve seat and cannot block the oil inlet hole of the lower valve seat. The oil at the oil inlet J flows to the right valve core chamber oil port through the bracket of the second pilot valve. Because the left end surface area of ​​the piston is smaller than the right end surface area of ​​the valve core, the leftward force acting on the valve core and the piston is greater than the rightward force, the valve core maintains the left position, and the brake control valve maintains the oil inlet J communicating with the load port S. The output brake pressure is the oil inlet pressure, that is, when the aircraft oil source is depressurized and oil is re-supplied, the brake control valve puts the aircraft in the parking brake working state.

9. The control method of the dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 7, characterized in that: After the second pilot valve is powered on and off, it is placed in the shutdown state: The second pilot valve is energized. When energized, the second solenoid drives the push rod to move downward, pushing the steel ball to block the oil inlet hole of the lower valve seat, and no longer contacts the upper valve seat. The oil in the control chamber on the right side of the valve core flows to the oil return port H through the pressure relief hole of the upper valve seat of the second pilot valve. The pressure in the control chamber on the right side of the valve core is reduced to the oil return pressure, and the pressure in the control chamber on the left side of the piston is still the oil inlet pressure. There is a pressure difference between the pressures on both sides of the valve core and the piston, which drives the valve core and the piston to move to the right. The load port S is no longer in communication with the oil inlet port J, and the load port S It communicates with the oil return port H for pressure relief, and the output pressure is the oil return pressure, and the aircraft is in the state of releasing the shutdown; after the second pilot valve is powered on and off, the oil in the control chamber on the right side of the valve core still flows to the oil return 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 oil inlet pressure, the valve core and the piston maintain the right position, and the load port S maintains communication with the oil return port H for pressure relief, and the output pressure is the oil return pressure, that is, after the second pilot valve is powered on and off, the brake control valve puts the aircraft in the state of releasing the shutdown.

10. The control method of the dual-control aircraft parking brake control valve with power-off holding function as claimed in claim 7, characterized in that: After the first pilot valve is energized and de-energized, it is placed in the parking brake working state: The first pilot valve is energized. When energized, the first solenoid drives the push rod to move downward, pushing the steel ball to block the oil inlet hole of the lower valve seat. The oil in the control chamber on the left side of the piston passes through the pressure relief hole of the upper valve seat of the first pilot valve to the return oil port H. The pressure in the control chamber on the left side of the piston is reduced to the return oil pressure, and the pressure in the control chamber on the right side of the valve core is still the return oil pressure. Under the action of the spring force on the right side of the valve core, the valve core and the piston are driven to move left, and the oil inlet J communicates with the load port S. The output brake pressure is the oil inlet pressure. At the same time, the oil at the oil inlet J is led 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 hole of the lower valve seat. The oil at the oil inlet J is led to the oil port of the right valve core chamber, and the pressure in the control chamber on the right side of the valve core increases to the oil inlet pressure, and the pressure in the control chamber on the left side of the piston is still the return oil pressure. , the valve core keeps the left position, the oil inlet J keeps communicating with the load port S, the output brake pressure is the oil inlet pressure, and the aircraft is in the parking brake working state; after the first pilot valve is powered off, under the action of the oil inlet pressure, the steel ball at the first pilot valve contacts with the upper valve seat and cannot block the oil inlet hole of the lower valve seat. Only the oil from port J flows to the left piston chamber oil port through the bracket of the first pilot valve, and the pressure in the control chamber on the right side of the valve core is still the oil inlet pressure. Because the left end surface area of ​​the piston is smaller than the right end surface area of ​​the valve core, the leftward force acting on the valve core and the piston is greater than the rightward force, and the valve core keeps the left position, and the brake control valve keeps the oil inlet J communicating with the load port S, and the output brake pressure is the oil inlet pressure, that is, after the first pilot valve is powered on and off, the brake control valve puts the aircraft in the parking brake working state.

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