Wide-temperature-range stable electro-hydraulic servo valve and method

Abstract

The invention belongs to the field of mechanical hydraulic pressure, and particularly relates to a wide-temperature-range stable electro-hydraulic servo valve and a method, and the electro-hydraulic servo valve comprises a torque motor part arranged on a shell, and a hydraulic amplification stage part, a power stage slide valve part, a fixed-difference pressure reduction part and a viscosity maintaining part which are arranged in the shell; according to the invention, the function of stabilizing the difference value between the oil inlet pressure and the oil return pressure is realized; according to the viscosity keeping mechanism, the change value of the viscosity of the hydraulic oil along with the temperature is creatively realized, the viscosity compensation can be carried out by applying changed pressure to the oil liquid, and finally, the viscosity of the oil liquid is not changed.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical hydraulics, and in particular relates to a wide temperature range stable electro-hydraulic servo valve and a method. Background Art

[0002] At present, electro-hydraulic servo valves are widely used in many important fields such as advanced civil aircraft, steel, power generation, etc. They are mainly used in servo mechanism control systems. Their functions account for more than 1 / 3 of the system, strongly supporting the development of related industries. At present, the requirements of hydraulic systems for servo valves are gradually increasing. When the external oil supply pressure and return oil pressure fluctuate greatly, the servo valve needs to maintain a stable output. In addition, when the temperature of the related supersonic equipment containing servo valves is extremely low at high altitudes and the temperature is extremely high when working at supersonic speeds, the equipment working in a wide temperature range has become the core technology of research and development. Therefore, the supersonic hydraulic system has put forward stability requirements for servo valves under a wide temperature range. At present, the mainstream forms of servo valves are traditional nozzle-baffle type, jet tube type, deflector jet type, linear direct drive type, and rotary direct drive type, none of which can solve the problem of stable output of servo valves when the external pressure changes greatly or the temperature changes greatly. Summary of the invention

[0003] Technical problem solved by the present invention: In order to solve the shortcoming that the existing servo valve cannot maintain a stable zero-position output when the external pressure and temperature change drastically, the present invention proposes a wide temperature range stable electro-hydraulic servo valve and method.

[0004] Technical solution of the present invention

[0005] A wide temperature range stable electro-hydraulic servo valve, the electro-hydraulic servo valve comprising a torque motor part arranged on a housing, and a hydraulic amplification stage part, a power stage slide valve part, a differential pressure reducing part, and a viscosity maintaining part arranged in the housing;

[0006] The torque motor part includes an upper magnet, a coil, a permanent magnet, an armature, a lower magnet, a spring tube, and a feedback rod. The permanent magnet is arranged between the upper magnet and the lower magnet, the coil is wound on the armature, the armature and the upper end of the feedback rod are installed on the spring tube, and the lower end of the feedback rod is connected to the power valve core of the power stage slide valve part;

[0007] The hydraulic amplification stage part includes a left nozzle, a baffle, a right nozzle, a left throttle hole component, an oil filter, and a right throttle hole component. The left nozzle and the right nozzle are symmetrically installed in the housing. The baffle is arranged between the left nozzle and the right nozzle. The left throttle hole component and the right throttle hole component are respectively sleeved on the left and right ends of the oil filter. The three parts are installed together in the corresponding oil filter hole of the housing.

[0008] The left end of the left nozzle, the left end of the left throttle component and the left end of the power valve core are connected through the housing oil passage; the right end of the right nozzle, the right end of the right throttle component and the right end of the power valve core are connected through the housing oil passage;

[0009] The power-level slide valve part includes a valve sleeve and a power valve core; the power valve core is installed in the valve sleeve and is installed in the valve sleeve hole of the housing together;

[0010] The differential pressure reducing part includes a spring and a pressure reducing valve core. The pressure reducing valve core is slidably installed in the hole of the housing. The spring is sleeved in the cylinder at the left end of the pressure reducing valve core, with the left side pressed against the housing, and the right side pressed against the left end surface of the left convex shoulder of the pressure reducing valve core. The left end of the pressure reducing valve core is connected to the overflow chamber R1, and the right end forms a closed chamber with the inner wall of the housing. A drainage oil channel is arranged on the pressure reducing valve core, and the drainage oil channel connects the closed chamber and the containing chamber Ps1. The convex shoulder of the pressure reducing valve core is arranged on the upper side of the oil inlet hole Ps of the housing, and the opening between the oil inlet hole Ps and the containing chamber Ps1 is controlled by the displacement of the pressure reducing valve core.

[0011] The viscosity maintaining part includes a left temperature sensor, an electric proportional relief valve, a right temperature sensor, and a resolver; the left temperature sensor is connected to the cavity on the left side of the left nozzle, and the right temperature sensor is connected to the cavity on the right side of the right nozzle. The output signals of the left temperature sensor and the right temperature sensor are transmitted to the resolver, and the output signal of the resolver is connected to the electric proportional relief valve after calculation; the upper side of the proportional relief valve oil channel is connected to the cavity R1, and the lower side is connected to the system return oil channel R.

[0012] Furthermore, the oil passage of the cavity Ps1 is connected to the oil passage where the oil filter is installed; the right side of the left nozzle and the left side of the right nozzle are in communication with the cavity R1.

[0013] Furthermore, the cylindricity of the working cylindrical surface 1 and the working cylindrical surface 2 of the pressure reducing valve core are both 0.001mm, the roughness is Ra0.1, the perpendicularity of the flow control surface and the center axis of the working cylindrical surface 2 is 0.001mm, and the diameter of the drainage oil channel is 1 / 5 to 1 / 4 of the diameter of the working cylindrical surface 2.

[0014] Furthermore, the minimum diameter of the oil drainage channel is 1.2 mm.

[0015] Furthermore, the square root of the ratio of the spring stiffness to the weight of the pressure reducing valve core is 3 to 5 times the natural frequency of the electro-hydraulic servo valve.

[0016] Furthermore, the output pressure R1 of the electric proportional relief valve is proportional to the input command signal output by the resolver.

[0017] Furthermore, the difference between the pressure value of the chamber Ps1 and R1 is a constant value, and the constant value is F 0 / A, where F 0 is the initial force of the spring, and A is the end surface area of ​​the pressure reducing valve core.

[0018] A working method of the viscosity maintaining part of the wide temperature range stable electro-hydraulic servo valve comprises the following steps:

[0019] S1: The left temperature sensor measures the temperature of the left cavity of the left nozzle, and the right temperature sensor measures the temperature of the right cavity of the right nozzle. The signals are transmitted to the solver at the same time, and the solver calculates the average value of the two temperatures.

[0020] S2: Obtain the temperature-viscosity characteristic curve and pressure-viscosity characteristic curve of the oil medium used, use MATLAB to fit the temperature-viscosity characteristic and pressure-viscosity function relationship, and finally solve the function relationship between pressure and temperature when the viscosity is a set constant value;

[0021] S3: Calculate the pressure of the left and right nozzles according to the measured temperature, and then output a command to the proportional relief valve;

[0022] S4: The output pressure R1 of the proportional relief valve changes accordingly, and the pressure at the left nozzle and the right nozzle changes accordingly. Finally, the change in oil viscosity caused by temperature change is compensated by the viscosity change with the pressure change, the viscosity is kept unchanged, and the servo valve can work stably in a wide temperature range.

[0023] Beneficial Effects

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) The differential pressure reducing part was invented, which has a small size, simple structure, and few parts. It can be inserted into the servo valve to achieve the function of stabilizing the difference between the oil inlet pressure and the oil return pressure;

[0026] 2) Invented a viscosity maintenance mechanism, creatively realized the change of hydraulic oil viscosity with temperature, and can use the oil to apply a variable pressure to compensate for viscosity, ultimately achieving constant oil viscosity;

[0027] 3) For the first time, the differential pressure reducing mechanism is applied to the electro-hydraulic servo valve to ensure that the difference between the servo valve oil inlet pressure and the oil return pressure is a constant value when there is external pressure interference, thus solving the problem of large changes in the valve output performance when the servo valve oil inlet pressure or oil return pressure changes alone or together;

[0028] 4) The viscosity maintaining mechanism is applied to the electro-hydraulic servo valve for the first time to ensure that the viscosity of the oil in the hydraulic amplifier part of the servo valve pre-stage remains unchanged, thereby ensuring stable pressure gain and flow gain of the hydraulic amplifier stage output, solving the problem of large changes in output performance when the servo valve works in a wide temperature range of extremely low and extremely high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of a wide temperature range stable electro-hydraulic servo valve according to an embodiment of the present invention;

[0030] Figure 2 It is a structural diagram of a pressure reducing valve core according to an embodiment of the present invention;

[0031] Figure 3 2 is a schematic diagram of the upper part of the pressure reducing valve core structure of an embodiment of the present invention;

[0032] Among them, 1. upper magnetic conductor, 2. coil, 3. permanent magnet, 4. armature, 5. lower magnetic conductor, 6. spring tube, 7. left nozzle, 8. left temperature sensor, 9. baffle, 10. right nozzle, 11. left throttle hole component, 12. oil filter, 13. valve sleeve, 14. power valve core, 15. feedback rod, 16. right throttle hole component, 17. spring, 18. pressure reducing valve core, 19. electric proportional relief valve, 20. right temperature sensor, 21. resolver, 22. housing; 18A, working cylindrical surface one; 18B, working cylindrical surface two, 18C, flow control surface, 18D, drainage oil channel. DETAILED DESCRIPTION

[0033] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0034] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] See also Figure 1 The present invention provides a wide temperature range stable electro-hydraulic servo valve, the electro-hydraulic servo valve comprising a torque motor part, a hydraulic amplification stage part, a power stage slide valve part, a differential pressure reducing part, and a viscosity maintaining part;

[0036] The torque motor part is arranged on the housing 22, including an upper magnet 1, a coil 2, a permanent magnet 3, an armature 4, a lower magnet 5, a spring tube 6, and a feedback rod 15. The permanent magnet 3 is arranged between the upper magnet 1 and the lower magnet 5, the coil 2 is wound on the armature 4, the armature 4 and the upper end of the feedback rod 15 are installed on the spring tube 6, and the lower end of the feedback rod is connected to the power valve core 14 of the power stage slide valve part;

[0037] The hydraulic amplification stage part includes a left nozzle 7, a baffle 9, a right nozzle 10, a left throttle hole component 11, an oil filter 12, and a right throttle hole component 16. The left nozzle 7 and the right nozzle 10 are symmetrically mounted on the housing, the baffle 9 is arranged between the left nozzle 7 and the right nozzle 10, the left throttle hole component 11 and the right throttle hole component 16 are respectively sleeved on the left and right ends of the oil filter 12, and the three parts are installed together in the corresponding oil filter hole of the housing 22;

[0038] The left end of the left nozzle 7, the left end of the left throttle component 11 and the left end of the power valve core 14 are connected through the oil passage of the housing 22; the right end of the right nozzle 10, the right end of the right throttle component 16 and the right end of the power valve core 14 are connected through the oil passage of the housing 22;

[0039] The power stage slide valve part includes a valve sleeve 13 and a power valve core 14; the power valve core 14 is installed in the valve sleeve 13 and is installed in the valve sleeve hole of the housing 22 together;

[0040] The differential pressure reducing part includes a spring 17 and a pressure reducing valve core 18. The pressure reducing valve core 18 is slidably installed in the hole of the housing 22. The spring 17 is sleeved in the cylinder at the left end of the pressure reducing valve core 18, with the left side pressed against the housing, and the right side pressed against the left end surface of the left convex shoulder of the pressure reducing valve core 18. The left end of the pressure reducing valve core 18 is connected to the overflow chamber R1, and the right end forms a closed chamber with the inner wall of the housing. A drainage oil passage 18D is provided on the pressure reducing valve core 18, and the drainage oil passage 18D connects the closed chamber and the accommodating chamber Ps1. The convex shoulder of the pressure reducing valve core 18 is provided on the upper side of the oil inlet hole Ps of the housing, and the opening between the oil inlet hole Ps and the accommodating chamber Ps1 is controlled by the displacement of the pressure reducing valve core 18.

[0041] The function of the differential pressure reduction part is: the difference between the chamber Ps1 and the chamber R1 is a constant value, and the constant value is F 0 / A. The calculation process is: analyze the force of the pressure reducing valve core 18,

[0042] R 1 A+F 0 =P s1 A

[0043] get

[0044] where F 0 is the initial force of the spring 17; A is the end surface area of ​​the pressure reducing valve core (18); Ps1 is the pressure after pressure reduction, and R1 is the overflow chamber pressure.

[0045] For the servo valve, the pressure difference between the oil inlet pressure Ps1 and the overflow chamber pressure R1 of the hydraulic amplifier stage and the slide valve stage of the servo valve remains constant, and the output performance of the entire valve is stable. If the servo valve is used in a hydraulic system, when the system temperature changes or load fluctuations cause changes in the oil supply and return oil pressures, no matter how the external oil inlet pressure Ps and return oil pressure R change, the servo valve can ensure that the difference between the chamber Ps1 and the chamber R1 is a constant value, and the output is stable, thereby ensuring that the output performance of the valve control system will not decay.

[0046] The viscosity maintaining part includes a left temperature sensor 8, an electric proportional relief valve 19, a right temperature sensor 20, and a resolver 21; the left temperature sensor 8 is connected to the cavity on the left side of the left nozzle 7, and the right temperature sensor 20 is connected to the cavity on the right side of the right nozzle 10. The output signals of the left temperature sensor 8 and the right temperature sensor 20 are transmitted to the resolver 21, and the resolver outputs the signal connected to the electric proportional relief valve 19 after calculation; the upper side of the oil passage of the proportional relief valve 19 is connected to the cavity R1, and the lower side is connected to the system return oil passage R; the oil passage of the cavity Ps1 is connected to the oil passage where the oil filter 12 is installed; the right side of the left nozzle 7 and the left side of the right nozzle 10 are in communication with the cavity R1.

[0047] In the present invention, the cylindricity of the working cylindrical surface 18A and the working cylindrical surface 18B of the pressure reducing valve core 18 are both 0.001mm and the roughness is Ra0.1, which can ensure that the pressure reducing valve core 18 moves smoothly in the hole of the housing 22, and the valve core has good wear resistance and long service life; the verticality of the flow control surface 18C and the central axis of the working cylindrical surface 18B is 0.001mm, which can ensure that the flow supply of the pressure reducing valve core 18 is fast at the moment of opening without delay; the diameter of the drainage oil channel 18D is 1 / 5 to 1 / 4 of the diameter of the working cylindrical surface 18B, so that the aperture will not be too large, which can ensure the strength of the middle cylindrical part of the pressure reducing valve core 18, ensure that there will be no excessive deformation when the pressure is passed, and the aperture will not be too small, which ensures the oil passing capacity and the valve core response frequency.

[0048] In the present invention, the minimum diameter of the oil drainage passage 18D is 1.2 mm.

[0049] In the present invention, the square root of the ratio of the stiffness of the spring 17 to the weight of the pressure reducing valve core 18 is 3 to 5 times the natural frequency of the electro-hydraulic servo valve, ensuring that the frequency of the differential pressure reducing part does not affect the bandwidth of the electro-hydraulic servo valve;

[0050] In the present invention, the output pressure R1 of the electric proportional relief valve 19 is proportional to the input command signal output by the resolver. The better the linearity, the more accurate the output pressure R1, and thus the better the oil viscosity is maintained;

[0051] In the present invention, the difference between the chambers Ps1 and R1 is a constant value, and the constant value is F 0 / A. Where F0 is the initial force of the spring 17, and A is the end surface area of ​​the pressure reducing valve core 18.

[0052] The present invention also provides a working method of the viscosity maintaining part of the wide temperature range stable electro-hydraulic servo valve, comprising the following steps:

[0053] S1: The left temperature sensor 8 measures the temperature of the left cavity of the left nozzle 7, and the right temperature sensor 20 measures the temperature of the right cavity of the right nozzle 10, and transmits the signal to the solver 21 at the same time, and the solver 21 calculates the average value of the two temperatures;

[0054] S2: Obtain the temperature-viscosity characteristic curve and pressure-viscosity characteristic curve of the oil medium used, use MATLAB to fit the temperature-viscosity characteristic and pressure-viscosity function relationship, and finally solve the function relationship between pressure and temperature when the viscosity is a set constant value;

[0055] S3: Calculate the pressure of the left nozzle 7 and the right nozzle 10 according to the measured temperature, and then output a command to the proportional relief valve 19;

[0056] S4: The output pressure R1 of the proportional relief valve 19 changes accordingly, and the pressures at the left nozzle 7 and the right nozzle 10 change accordingly, and finally the change in oil viscosity caused by temperature change is compensated by the viscosity change with the pressure change, so that the viscosity is kept unchanged and the servo valve can work stably in a wide temperature range.

[0057] The wide temperature range stable electro-hydraulic servo valve proposed in the present invention has the following working principle: the external pressure is Ps for the oil supply pressure of the valve, which is input to the hydraulic amplifier stage and the slide valve stage of the servo valve through the pressure reducing valve core 18, and flows to the overflow chamber after operation. The pressure difference between the oil inlet end pressure Ps1 of the hydraulic amplifier stage and the slide valve stage of the servo valve and the pressure at the overflow chamber end R1 remains constant. When the coil 2 inputs a positive current, the armature 4 is acted upon by the electromagnetic force and moves counterclockwise around the rotation center of the spring tube 6, driving the baffle 9 to deflect to the right, thereby reducing the pressure on the left side of the left nozzle 7 and increasing the pressure on the right side of the right nozzle 10, and then the power valve core 14 moves to the left, and the high-pressure oil outputs pressure and flow through the opening of the power valve core 14 and the valve sleeve 13. In addition, the displacement of the power valve core 14 transmits the force to the spring tube 6 through the feedback rod 15, and finally achieves force balance, and the valve core stops at the specified position. Similarly, when the coil 2 inputs a negative current, the movement direction of the internal parts of the servo valve is opposite to that described above. The servo valve also includes a viscosity maintaining part, and its working process is as follows:

[0058] When the oil temperature rises, the viscosity of the oil becomes lower, and the flow rate between the left nozzle 7 and the right nozzle 10 and the baffle 9 increases, and the throttling capacity at the nozzle-baffle is stronger, and the pressure gain and flow gain of the hydraulic amplifier stage will increase, the stability margin of the servo valve will decrease, and resonance will easily occur, and the viscosity will change. Since the left nozzle 7 and the right nozzle 10 cannot be absolutely the same, the valve core zero position will change. At this time, the resolver 21 calculates the output signal according to the temperature and transmits it to the electric proportional relief valve 19. The overflow pressure corresponding to the proportional relief valve 19 increases, and the overflow chamber pressure R1 and the pressure on the left side of the left nozzle 7 and the right side of the right nozzle 10 also increase, and the viscosity increases to the initial value, thereby ensuring that the pressure gain and flow gain of the pressure amplifier stage are restored to the initial value, and the servo valve performance is restored to the initial state, so that the servo valve performance remains unchanged at high temperature.

[0059] When the oil temperature drops, the viscosity of the oil increases, and the flow rate between the left nozzle 7 and the right nozzle 10 and the baffle 9 decreases, and the throttling capacity at the nozzle-baffle is weakened, and the pressure gain and flow gain of the hydraulic amplifier stage will decrease, the response speed of the servo valve will slow down, and the viscosity of the oil changes. Since the left nozzle 7 and the right nozzle 10 cannot be absolutely the same, the valve core zero position changes. At this time, the resolver 21 calculates the output signal according to the temperature and transmits it to the electric proportional relief valve 19. The overflow pressure corresponding to the proportional relief valve 19 decreases, and the overflow chamber pressure R1 and the pressure on the left side of the left nozzle 7 and the right side of the right nozzle 10 also decrease, and the viscosity decreases to the initial value, thereby ensuring that the pressure gain and flow gain of the pressure amplifier stage are restored to the initial value, and the servo valve performance is restored to the initial state, so that the servo valve performance remains unchanged at low temperatures.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A wide temperature range stable electro-hydraulic servo valve, characterized in that: The electro-hydraulic servo valve comprises a torque motor part arranged on the housing, and a hydraulic amplification stage part, a power stage slide valve part, a differential pressure reducing part, and a viscosity maintaining part arranged in the housing; The torque motor part includes an upper magnet, a coil, a permanent magnet, an armature, a lower magnet, a spring tube, and a feedback rod. The permanent magnet is arranged between the upper magnet and the lower magnet, the coil is wound on the armature, the armature and the upper end of the feedback rod are installed on the spring tube, and the lower end of the feedback rod is connected to the power valve core of the power stage slide valve part; The hydraulic amplification stage part includes a left nozzle, a baffle, a right nozzle, a left throttle hole component, an oil filter, and a right throttle hole component. The left nozzle and the right nozzle are symmetrically installed in the housing. The baffle is arranged between the left nozzle and the right nozzle. The left throttle hole component and the right throttle hole component are respectively sleeved on the left and right ends of the oil filter. The three parts are installed together in the corresponding oil filter hole of the housing. The left end of the left nozzle, the left end of the left throttle component and the left end of the power valve core are connected through the housing oil passage; the right end of the right nozzle, the right end of the right throttle component and the right end of the power valve core are connected through the housing oil passage; The power-level slide valve part includes a valve sleeve and a power valve core; the power valve core is installed in the valve sleeve and is installed in the valve sleeve hole of the housing together; The differential pressure reducing part includes a spring and a pressure reducing valve core. The pressure reducing valve core is slidably installed in the hole of the housing. The spring is sleeved in the cylinder at the left end of the pressure reducing valve core, with the left side pressed against the housing, and the right side pressed against the left end surface of the left convex shoulder of the pressure reducing valve core. The left end of the pressure reducing valve core is connected to the overflow chamber R1, and the right end forms a closed chamber with the inner wall of the housing. A drainage oil channel is arranged on the pressure reducing valve core, and the drainage oil channel connects the closed chamber and the containing chamber Ps1. The convex shoulder of the pressure reducing valve core is arranged on the upper side of the oil inlet hole Ps of the housing, and the opening between the oil inlet hole Ps and the containing chamber Ps1 is controlled by the displacement of the pressure reducing valve core. The viscosity maintaining part includes a left temperature sensor, an electric proportional relief valve, a right temperature sensor, and a resolver; the left temperature sensor is connected to the cavity on the left side of the left nozzle, and the right temperature sensor is connected to the cavity on the right side of the right nozzle. The output signals of the left temperature sensor and the right temperature sensor are transmitted to the resolver, and the output signal of the resolver is connected to the electric proportional relief valve after calculation; the upper side of the proportional relief valve oil channel is connected to the cavity R1, and the lower side is connected to the system return oil channel R.

2. A wide temperature range stable electro-hydraulic servo valve as claimed in claim 1, characterized in that: The oil passage of the cavity Ps1 is connected to the oil passage where the oil filter is installed; the right side of the left nozzle and the left side of the right nozzle are in communication with the cavity R1.

3. A wide temperature range stable electro-hydraulic servo valve as claimed in claim 1, characterized in that: The cylindricity of the working cylindrical surface 1 and the working cylindrical surface 2 of the pressure reducing valve core are both 0.001mm, the roughness is Ra0.1, the perpendicularity of the flow control surface and the center axis of the working cylindrical surface 2 is 0.001mm, and the diameter of the drainage oil channel is 1 / 5 to 1 / 4 of the diameter of the working cylindrical surface 2.

4. A wide temperature range stable electro-hydraulic servo valve as claimed in claim 3, characterized in that: The minimum diameter of the oil drainage channel is 1.2 mm.

5. The wide temperature range stable electro-hydraulic servo valve according to claim 1, characterized in that: The square root of the ratio of the spring stiffness to the weight of the pressure reducing valve core is 3 to 5 times the natural frequency of the electro-hydraulic servo valve.

6. The wide temperature range stable electro-hydraulic servo valve according to claim 1, characterized in that: The output pressure R1 of the electric proportional relief valve is proportional to the input command signal output by the resolver.

7. A wide temperature range stable electro-hydraulic servo valve as claimed in claim 6, characterized in that: The difference between the pressure value of the chamber Ps1 and R1 is a constant value, and the constant value is F0 / A, where F0 is the initial force of the spring and A is the end surface area of ​​the pressure reducing valve core.

8. A method for operating the viscosity maintaining portion of the wide temperature range stable electro-hydraulic servo valve as claimed in claim 1, characterized in that: The following steps are involved: S1: The left temperature sensor measures the temperature of the left cavity of the left nozzle, and the right temperature sensor measures the temperature of the right cavity of the right nozzle. The signals are transmitted to the solver at the same time, and the solver calculates the average value of the two temperatures. S2: Obtain the temperature-viscosity characteristic curve and pressure-viscosity characteristic curve of the oil medium used, use MATLAB to fit the temperature-viscosity characteristic and pressure-viscosity function relationship, and finally solve the function relationship between pressure and temperature when the viscosity is a set constant value; S3: Calculate the pressure of the left and right nozzles according to the measured temperature, and then output a command to the proportional relief valve; S4: The output pressure R1 of the proportional relief valve changes accordingly, and the pressure at the left nozzle and the right nozzle changes accordingly. Finally, the change in oil viscosity caused by temperature change is compensated by the viscosity change with the pressure change, the viscosity is kept unchanged, and the servo valve can work stably in a wide temperature range.

Images