Low-leakage high-response high-reliability pressure servo valve

Abstract

The application discloses a kind of low leakage high response high reliability pressure servo valve, the pressure servo valve includes torque motor, valve body, spool, reset spring and oil inlet nozzle, oil return nozzle and baffle composition, oil inlet nozzle is close to baffle at zero, oil return nozzle and baffle exist initial spacing, by designing the internal flow passage of valve body, make nozzle control cavity pressure and working oil port pressure respectively act on the left and right ends of spool, adjust spool rod diameter so that the action area of both ends is not equal, reach the purpose of using lower nozzle control cavity pressure to control higher working oil port pressure, improve the response speed of pressure servo valve.The right end of spool is equipped with reset spring, push spool to the leftmost position at zero, connect working oil port and oil return port, realize safety protection function.The application can solve the problem of low leakage and high response conflict of existing double-nozzle baffle pressure servo valve, and achieve the development goal of low leakage, high response and high reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to a servo valve, in particular to a low-leakage high-response high-reliability pressure servo valve. BACKGROUND

[0002] The pressure servo valve is an important control element in the electronic anti-skid brake system of an airplane. By precisely applying a high-frequency pressure signal to the wheel brake system, the point brake mode is used to prevent tire lock and shorten the braking distance. The existing pressure servo valve is composed of a torque motor, a front-stage nozzle flapper element, a power amplification stage spool element, etc. The front-stage nozzle flapper element works according to the throttling principle. By adjusting the distance of the flapper, the pressure difference between the two nozzle cavities is changed and acts on both ends of the spool to achieve the control of the spool movement.

[0003] With the development of miniaturization and light weight of hydraulic components and the high efficiency of the airplane hydraulic system, it is expected that the pressure servo valve will achieve the goals of low leakage, high response and high reliability. However, the existing double-nozzle flapper type pressure servo valve cannot meet this requirement, mainly due to the following problems:

[0004] (1) The two nozzles simultaneously output flow, resulting in a large amount of leakage, which cannot improve the efficiency of the airplane system;

[0005] (2) If the leakage of the servo valve is to be reduced, the nozzle diameter needs to be reduced, which reduces the output efficiency of the front stage, reduces the response speed of the servo valve, and cannot apply high-frequency pressure to the brake system, increasing the braking distance and being detrimental to the safety of the airplane brake;

[0006] (3) The distance between the nozzle and the flapper of the traditional double-nozzle servo valve is very small (usually 0.03mm-0.05mm), and the upper limit is 1 / 16 of the nozzle diameter, which has poor anti-pollution ability and is prone to unilateral nozzle blockage. The pressure in the blocked nozzle cavity rises, causing a pressure difference between the two nozzle cavities to exist all the time, the spool cannot return to zero, the load pressure cannot be released, and the brake wheel is locked, causing a fault.

[0007] To solve the above problems and achieve the development goal of low leakage, high response and high reliability of the pressure servo valve, the present application provides a nozzle flapper pressure servo valve structure. SUMMARY

[0008] The purpose of the present application is to provide a low-leakage high-response high-reliability pressure servo valve to achieve the development requirements of low leakage, high response and high reliability, and to improve the efficiency and reliability of the airplane brake system.

[0009] To achieve the above purpose, the technical solution adopted by the present application is:

[0010] The low-leakage high-response high-reliability pressure servo valve adopts a torque motor, a pre-stage nozzle baffle element, a power amplification stage spool element and the like. The nozzle is divided into an oil inlet nozzle and an oil return nozzle, the oil inlet nozzle is tightly attached to the baffle at zero position, and the oil return nozzle has an initial spacing with the baffle, only one oil inlet nozzle greatly reduces the leakage of the servo valve, and at zero position, the baffle is tightly attached to the oil inlet nozzle, which greatly reduces the nozzle leakage at zero position. The oil inlet nozzle is communicated with the oil inlet hole of the servo valve, and a filter is installed in front of the oil inlet nozzle. The oil return nozzle is communicated with the oil return port of the servo valve.

[0011] Further, the left cavity of the spool is communicated with the nozzle control cavity, the annular cavity at the right end of the spool is communicated with the working oil port through the through hole of the spool, the pressure of the nozzle control cavity under the joint action of the oil inlet nozzle and the oil return nozzle is introduced into the left end of the spool, and the pressure of the working oil port is introduced into the annular cavity at the right end of the spool through the through hole of the spool. The acting areas of the left and right cavities of the spool can be adjusted by adjusting the diameters of the rods, so that the purpose of controlling the higher working oil port pressure by using the lower nozzle control cavity pressure is achieved.

[0012] Further, the dead cavity generated at the right end of the spool is introduced into the oil return port of the servo valve through the hole in the spool.

[0013] Further, the right end of the spool is provided with a reset spring, which pushes the spool to the leftmost position at zero position, so as to realize the communication between the working oil port and the oil return port and realize the safety protection function.

[0014] Compared with the prior art, the beneficial effects of the present application are:

[0015] (1) After the nozzle is divided into an oil inlet nozzle and an oil return nozzle, under the condition of the same nozzle diameter, only one nozzle outputs flow, so that the leakage of the servo valve can be reduced by half;

[0016] (2) The nozzle diameter can be appropriately increased, so that the response speed of the servo valve can be improved under the condition of moderately reducing the leakage of the servo valve;

[0017] (3) The distance between the nozzle and the baffle is not limited by the nozzle diameter, the spacing can be increased, the anti-pollution ability is improved, when the oil inlet nozzle is blocked, the pressure of the nozzle control cavity is zero, under the action of the reset spring, the servo valve returns to zero position, preventing the tire from being locked. When the oil return nozzle is blocked, the baffle can block the oil inlet nozzle under the action of the torque motor, so that the servo valve can still return to zero position, and the safety and reliability of the servo valve are improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the structural principle diagram of the pressure servo valve scheme of the present application.

[0019] Fig. 1. Torque motor; 2. Valve body; 3. Filter; 4. Oil inlet nozzle flow channel; 5. Dead space; 6. Limiting block; 7. Reset spring; 8. Ring cavity at right end of spool valve; 9. Spool valve; 10. Oil inlet; 11. Spool valve through hole; 12. Spool valve inner hole; 13. Working oil port; 14. Oil return port; 15. Left cavity of spool valve; 16. Oil return nozzle flow channel; 17. Oil inlet nozzle; 18. Oil return nozzle; 19. Baffle; 20. Nozzle control cavity. DETAILED DESCRIPTION

[0020] Combination Figure 1 An electro-hydraulic pressure servo valve for controlling pressure of an airplane brake system mainly comprises a torque motor 1, a valve body 2, a spool valve 9, and an oil inlet nozzle 17, an oil return nozzle 18, and a baffle 19. The torque motor 1 is consistent with the principle of a conventional torque motor, and no special introduction is made.

[0021] The oil inlet port 10 of the servo valve enters the filter 3 through the oil inlet nozzle flow channel 4, and then high-pressure oil enters the oil inlet nozzle 17. The oil inlet nozzle 17 is in close contact with the baffle 19 at zero position, and the oil return nozzle 18 has a spacing with the baffle 19. The oil return nozzle 18 communicates with the oil return port 14 through the oil return nozzle flow channel 16.

[0022] The left cavity 15 of the spool valve 9 communicates with the nozzle control cavity 20, and the ring cavity 8 at the right end of the spool valve communicates with the working oil port 13 through the spool valve through hole 11. The right end of the spool valve 9 generates a dead space 5 inside the limiting block 6, and the oil in the dead space 5 can be introduced into the oil return port 14 through the spool valve inner hole 12. The right end of the spool valve 9 is provided with a reset spring 7, which pushes the spool valve 9 to the leftmost position at zero position, so as to realize the communication between the working oil port 13 and the oil return port 14.

[0023] At zero position, the oil inlet nozzle 17 is in close contact with the baffle 19, and the pressure of the nozzle control cavity 20 is the oil return pressure, so the pressures of the left cavity 15 of the spool valve and the ring cavity 8 at the right end of the spool valve are equal. The spool valve 9 is pushed to the leftmost position under the action of the reset spring 9, so as to realize the communication between the working oil port 13 and the oil return port 14.

[0024] In working state, the baffle 19 moves to the left under the action of the torque motor 1, the spacing between the baffle 19 and the oil inlet nozzle 17 increases, the spacing between the baffle 19 and the oil return nozzle 18 decreases, and the pressure of the nozzle control cavity 20 increases. The left cavity 15 of the spool valve increases synchronously with the pressure of the nozzle control cavity 20, pushes the spool valve 9 to move to the right, the oil inlet port 11 gradually opens, the oil return port 14 gradually closes, and the pressure of the working oil port 13 gradually rises. The pressure of the ring cavity 8 at the right end of the spool valve synchronously rises, and force balance is achieved between the pressure of the ring cavity 8 at the right end of the spool valve and the left cavity 15 of the spool valve and the reset spring, so as to realize the stable output of the pressure of the working oil port 13.

[0025] The application provides a novel pressure servo valve principle structure, which makes the oil inlet nozzle 17 inlet oil and the oil return nozzle 18 return oil, reduces the servo valve leakage, and simultaneously can increase the nozzle diameter to improve the response speed and reliability of the servo valve under the condition of moderately reducing the servo valve leakage.

Claims

1. A low leakage, high response, high reliability pressure servo valve comprising a torque motor, a valve body, a spool, a return spring and a flapper, the flapper being located in a nozzle control chamber, characterized in that: The oil inlet nozzle and the oil return nozzle are also included, the servo valve oil inlet is communicated with the oil inlet nozzle through the oil inlet nozzle channel, the oil return nozzle is communicated with the oil return port through the oil return nozzle channel, the oil inlet nozzle is close to the baffle at zero position, the oil return nozzle has a distance with the baffle, at work, the baffle moves left under the action of the torque motor, the distance between the baffle and the oil inlet nozzle increases, the distance between the baffle and the oil return nozzle decreases, and the pressure of the nozzle control chamber increases; The spool valve divides the cavity into the spool valve left cavity, the working oil port and the spool valve right end annular cavity, the spool valve left cavity is communicated with the nozzle control chamber, and the spool valve right end annular cavity is communicated with the working oil port through the spool valve through hole; The spool valve right end generates a dead cavity in the inside of the limiting block, and the dead cavity can introduce the oil into the oil return port through the spool valve inner hole; The right end of the spool valve is provided with the reset spring, at zero position, the pressure of the nozzle control chamber is the oil return pressure, the pressure of the spool valve left cavity and the spool valve right end annular cavity is equal, the spool valve is pushed to the leftmost position under the action of the reset spring, and the working oil port is communicated with the oil return port, at work, the torque motor, the pressure of the spool valve left cavity is increased synchronously with the pressure of the nozzle control chamber, the spool valve is pushed to move right, the oil inlet port is gradually opened, the oil return port is gradually closed, the working oil port pressure is gradually increased, the pressure of the spool valve right end annular cavity is synchronously increased, the force balance is carried out between the pressure of the spool valve left cavity and the reset spring, and the working oil port is stably outputted. The filter is arranged in front of the oil inlet nozzle.

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