CN206092566U - Direct action type 2D electro -hydraulic pressure servo valve - Google Patents

Abstract

The utility model relates to a direct action type 2D electro -hydraulic pressure servo valve. Its characterized in that comprises valve body module, electromechanical converter module, drive mechanism module and displacement sensor module, and the displacement sensor module cooperatees with the valve body module, and the electromechanical converter module cooperatees through drive mechanism module and valve body module, the displacement of 2D piston and the rotary electromagnet signal of telecommunication of electromechanical converter module constitute the closed loop feedback in the displacement sensor module real -time supervision valve body module. The utility model discloses a control rotary electromagnet's deflection angle changes the axial displacement distance of case, and then the size that changes the spring force comes adjustment system's pressure, has structurally simplified original two -stage or multiple -order structural style greatly, accords with the simple compact requirement of trade.

Description

Direct acting 2D electro-hydraulic pressure servo valve

technical field

The utility model belongs to an electro-hydraulic servo valve in the field of fluid transmission and control, in particular to a direct-acting 2D electro-hydraulic pressure servo valve.

Background technique

The electro-hydraulic servo control technology organically combines the advantages of fluid transmission control technology and information electronic technology. It has the advantages of high power amplification, fast response, small dead zone, and continuous two-way control of output flow and pressure. It is used in aerospace, cutting-edge weapons, etc. , iron and steel, electric power generation and other important national strategic military industry fields have been widely used. The electro-hydraulic pressure servo valve is an important and ideal servo component in the force control system. It is a hydraulic control valve that accepts analog electric control signals, and the output pressure changes with the magnitude and polarity of the electric control signals and responds quickly. It has small size, With the advantages of small inertia, fast response and high sensitivity, it is widely used in material testing machines, structural fatigue testing machines, aircraft and vehicle hydraulic control systems and ship steering gear control systems.

At present, the electro-hydraulic pressure servo valves are mainly two types of nozzle baffle type and jet tube type pressure servo valves, but the technology is mostly monopolized by foreign countries; the most widely used pressure servo valves in China are mainly two-stage or three-stage electro-hydraulic pressure servo valves. Servo valves, these servo valves have excellent performance, but they are extremely complex in structure, difficult to manufacture, and the service conditions are quite harsh, requiring high oil cleanliness and high failure rate.

Due to various deficiencies of pressure servo valves, electro-hydraulic proportional pressure control components, such as electro-hydraulic proportional pressure reducing valves and overflow valves, are often used in situations where the accuracy is not high in actual production, and linear displacement sensors (LVDT) are used to control The position of the spool is measured and closed-loop controlled to form an electric feedback type direct-acting proportional pressure control valve, which can greatly improve the positioning stiffness of the spool and the control accuracy of the output force, and is used to replace the electro-hydraulic pressure servo valve to realize control of the system. Force control, but the control accuracy is slightly inferior.

Utility model content

Aiming at the problems existing in the prior art, the purpose of this utility model is to provide a technical solution of a direct-acting 2D electro-hydraulic pressure servo valve, by controlling the deflection angle of the rotating electromagnet to change the axial moving distance of the 2D piston, and then Changing the size of the spring force to adjust the pressure of the system greatly simplifies the original two-stage or multi-stage structure in structure, which meets the simple and compact requirements of the industry.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that it consists of a valve body module, an electromechanical converter module, a transmission mechanism module and a displacement sensor module, the displacement sensor module cooperates with the valve body module, and the electromechanical converter module The module cooperates with the valve body module through the transmission mechanism module; the displacement sensor module monitors the displacement of the 2D piston in the valve body module in real time and forms a closed-loop feedback with the electric signal of the rotating electromagnet of the electromechanical converter module.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that the valve body module includes a valve core, a 2D piston, a spring and a valve body, the 2D piston is set on the right side of the valve body, and the valve core is set on the side of the valve body. On the left side, the 2D piston has two movement directions of rotation and axial sliding in the valve body; one end of the 2D piston is provided with a shoulder, and a pair of high-pressure holes and a pair of low-pressure holes are arranged on the shoulder, and a pair of high-pressure holes and the inlet The oil P port is connected, and a pair of low-pressure holes are connected with the oil outlet T port; the inner hole wall of the cylinder in the valve body is symmetrically opened with a pair of damping chute matching the shoulder of the 2D piston, and the shoulder of the 2D piston is connected to the cylinder. The left sensitive chamber and the right sensitive chamber are formed between the concentric rings arranged on the right side of the 2D piston, the 2D piston is installed in the cylinder barrel, a pair of high pressure holes, a pair of low pressure holes and a pair of damping chute on the shoulder of the 2D piston Intersect to form four small opening areas in series to form a hydraulic resistance half-bridge, which controls the pressure change of the left sensitive chamber, and the right sensitive chamber is connected to the oil inlet P port for high pressure, and the pressure of the left and right sensitive chambers is controlled by the hydraulic resistance half-bridge. The generated pressure difference drives the 2D piston to move axially; the spool is provided with a left end shoulder, a right end shoulder and a middle shoulder, the left end shoulder of the spool corresponds to the oil inlet P port, and the middle shoulder corresponds to the control A The right end shoulder corresponds to the oil outlet T port, and the left end shoulder, the right end shoulder and the middle shoulder are slidably fitted with the inner hole of the valve body; a left gasket and a right gasket are arranged between the spool and the 2D piston The spring is set between the left gasket and the right gasket. The right end of the valve core is in contact with the right gasket through a steel ball. The left end of the 2D piston is in contact with the left gasket through a steel ball. The axial movement of the 2D piston can be controlled by the spring. Converted to axial movement of the spool.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that the electromechanical converter module includes a rotating electromagnet, a connecting plate and an electromagnet protective cover that cooperate with each other; the transmission mechanism module includes a spring holding rod, an electromagnetic Iron zero position holding spring, spring washer, spring retainer, upper shift lever and lower shift fork, the spring retainer is set on the connecting plate, the spring retainer is provided with the spring retainer rod, and the spring retainer is sleeved with an electromagnetic The iron zero position keeps the spring and the spring washer. One end of the upper lever is connected to the rotating shaft of the rotating electromagnet. It can slide on the spring holding rod; one end of the upper lever connected to the rotating shaft of the rotating electromagnet is set to an elliptical outer contour, the upper end of the lower shift fork is engaged with the elliptical outer contour, and the lower end of the lower shift fork is connected to the valve body module. 2D Pistons.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that the displacement sensor module includes an LVDT displacement sensor, and the sensor mandrel of the LVDT displacement sensor is connected to the 2D piston of the valve body module through a threaded connecting rod.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that a valve sleeve is arranged at the left end of the valve body, the valve core is installed in the valve sleeve, and an interference fit is installed at the right end of the valve core to limit the radial rotation of the valve core. The limit pin slides in the U-shaped groove of the valve sleeve.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that an end cover is provided on one side of the valve body, and a box cover is provided on the other side of the valve body.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that the left end surface of the spool is configured as a disc-shaped structure, and when the spool moves left and right, the disc-shaped structure of the spool is in contact with the valve body and the valve sleeve. An extruded oil film is formed between them.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that the upper end of the lower shift fork is a U-shaped fork with an upward opening, and the U-shaped fork is snap-fitted with the elliptical outer contour.

The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that the LVDT displacement sensor is installed on the sensor bracket.

The beneficial effects of the utility model are mainly manifested in:

1. In view of the lack of poor anti-pollution ability of the existing electro-hydraulic pressure servo valve, the 2D screw servo and pressure servo control technology are combined to form a direct-acting 2D electro-hydraulic pressure servo valve with compact structure and advanced principle, which simplifies the pressure servo The structure of the valve improves its anti-pollution ability;

2. Use the extruded oil film buffer theory to design the valve core structure (a disc-shaped structure is added to the left end of the valve core as a damping module). During the left and right movement of the valve core, the viscous damping of the system can be increased, and the valve core can be guaranteed by increasing the system damping ratio. stable performance;

3. The LVDT displacement sensor is used to monitor the axial displacement of the 2D piston in real time, and forms a closed-loop feedback with the electric signal of the one-way rotating electromagnet to improve the overall control accuracy and dynamic response capability of the valve;

4. The spring contact between the 2D piston and the valve core can not only realize the force transmission, but also prevent excessive pressure, so that the force control system will not "lock".

Description of drawings

Figure 1 is a schematic structural diagram of a direct-acting 2D electro-hydraulic pressure servo valve;

Fig. 2 is a sectional view of the valve body;

Fig. 3 is the structural representation of 2D piston;

Fig. 4 is a schematic diagram of the valve core structure with a damping disk buffer;

Fig. 5 is the side schematic diagram of connecting plate;

Fig. 6 is a schematic diagram of the working principle of the direct-acting 2D electro-hydraulic pressure servo valve.

detailed description

The utility model is further described below in conjunction with the accompanying drawings of the description:

1-6, a direct-acting 2D electro-hydraulic pressure servo valve includes a first screw 1, a second screw 4, a third screw 6, a fourth screw 12, a fifth screw 13, a sixth screw 14, a Seventh screw 18, eighth screw 21 and ninth screw 25, first O-ring 2, second O-ring 27, third O-ring 29, valve body 3, rotating electromagnet 5, connecting plate 7 , spring retaining rod 8, electromagnet zero position retaining spring 9, spring washer 10, spring retainer 11, upper lever 15, fastening steel ball 16, aviation socket 17, lower shift fork 19, threaded connecting rod 20, sensor Mandrel 22, LVDT displacement sensor 23, sensor bracket 24, box cover 26, concentric ring 28, cylinder 30, 2D piston 31, right gasket 32, first steel ball 33, second steel ball 36, spring 34, left Gasket 35, limit pin 37, valve sleeve 38, valve core 39, end cover 40.

Among them, the first screw 1 connects the end cover and the valve body, the second screw 4 connects the electromagnet protective cover and the connecting plate 7, the third screw 6 connects the rotating electromagnet and the connecting plate 7, and the fourth screw 12 connects the spring holder 11 and the connecting plate 7. Connecting plate, the fifth screw 13 connects the box cover 26 and the electromagnet protective cover, the sixth screw 14 locks the upper lever 15, the seventh screw 18 is used to connect the aviation socket 7 to the box cover 26, and the eighth screw 21 is used After locking the shift fork 19, the ninth screw 25 connects the box cover and the connecting plate; the first O-ring 2 is used to seal the end cover and the valve body, and the second O-ring 27 is used to seal the 2D piston 31 and the connection The plate 7 and the third O-ring 29 are used to seal the valve body 3 and the connecting plate 7 . These settings are common settings and will not be repeated here.

The direct-acting 2D electro-hydraulic pressure servo valve of the utility model is composed of a valve body module, an electromechanical converter module, a transmission mechanism module and a displacement sensor module. The displacement sensor module cooperates with the valve body module to monitor the displacement of the 2D piston. The mechanical converter module cooperates with the valve body module through the transmission mechanism module to rotate the 2D piston; the displacement sensor module monitors the displacement of the 2D piston in the valve body module in real time and constitutes the electric signal of the one-way rotating electromagnet of the electromechanical converter module closed loop feedback.

The valve body module includes a valve core, a 2D piston, a spring and a valve body. The 2D piston is set on the right side of the valve body, and the valve core is set on the left side of the valve body. The 2D piston has two movements of rotation and axial sliding in the valve body Direction; 2D There is a shoulder at one end of the piston, and a pair of high-pressure holes b and a pair of low-pressure holes c are arranged on the shoulders. A pair of high-pressure holes communicate with the oil inlet P port, and a pair of low-pressure holes communicate with the oil outlet T port. The oil inlet P port is the oil inlet port, the pressure there is the system pressure, and the oil outlet T port is the oil return port; the inner hole wall of the cylinder in the valve body is symmetrically opened with a pair of damping slopes matching the shoulder of the 2D piston. groove( ), the left sensitive chamber f and the right sensitive chamber g are formed between the shoulder of the 2D piston and the cylinder and the concentric ring arranged on the right side of the 2D piston, the 2D piston is installed in the cylinder, and a pair of high pressure on the shoulder of the 2D piston The hole and a pair of low-pressure holes intersect with a pair of damping chute to form four small openings connected in series to form a half-bridge of hydraulic resistance to control the pressure change of the left sensitive chamber, and the right sensitive chamber is connected to the oil inlet P port for high pressure. The pressure in the sensitive chamber is controlled by the hydraulic resistance half bridge, and the pressure difference generated drives the 2D piston to move axially; the spool is provided with a left end shoulder, a right end shoulder and a middle shoulder, and the left end shoulder of the spool Corresponding to the oil inlet P port, the middle shoulder corresponds to the control A port, the right end shoulder corresponds to the oil outlet T port, the left end shoulder, the right end shoulder and the middle shoulder are slidably fitted with the inner hole of the valve; when the 2D piston When turning clockwise (looking left from the side of the transmission mechanism), the intersection area of the high-pressure hole and the damping chute decreases, and the intersection area of the low-pressure groove and the damping chute increases. At this time, the pressure in the left sensitive chamber decreases, and the right sensitive chamber The cavity pressure remains unchanged, and the 2D piston moves to the left. In the process of moving to the left, the intersection area of the high pressure hole and the damping chute increases, the intersection area of the low pressure groove and the damping chute decreases, and the 2D piston finally stabilizes at a certain position. At this time, the high pressure hole, the low pressure hole and the damping chute With unequal widths on both sides, the 2D piston creates a force to the left, which acts on the spring, compressing it. This spring force eventually balances the force that controls the A port pressure on the left side of the spool.

The cylinder barrel 30 is close to the shoulder of the valve body 3, and the fastening steel ball 16 presses the cylinder barrel inside the valve body through the chute inside the valve body, and prevents it from radial rotation; the valve core and the 2D piston There is a left gasket and a right gasket between them, the spring is arranged between the left gasket and the right gasket, the right end of the spool is in contact with the right gasket through the second steel ball 36, and the left end of the 2D piston is in contact with the right gasket through the first steel ball 33. The left gasket is in contact with each other, and the axial movement of the 2D piston can be converted into the axial movement of the spool through the spring.

At the initial moment, the right end of the right gasket 32 is in close contact with the cylinder barrel 30, and the left end of the right gasket 32 is in contact with the spring 34; the valve sleeve 38 is installed on the left end of the valve body 3 with an interference fit, and the valve core 39 is installed on the valve sleeve In 38, a limit pin 37 is installed with interference fit at the right end of the spool, and the limit pin slides in the U-shaped groove of the valve sleeve to limit the radial rotation of the spool and reduce pressure fluctuations caused by machining errors.

As shown in Figure 4, the left end surface of the valve core 39 is set as a disc-shaped structure. When the valve core moves left and right, an extruded oil film is formed between the disc-shaped structure of the valve core, the valve body and the valve sleeve, and its function is In order to introduce the extrusion oil film damping coefficient, increase the viscous damping of the system, and increase the damping ratio to stabilize the system.

As shown in Figure 5, the transmission mechanism module includes a spring retaining rod, an electromagnet zero position retaining spring, a spring washer, a spring retainer, an upper shift lever and a lower shift fork. The spring retainer is arranged on the connecting plate, and the spring retainer The spring holding rod is set, and the spring holding rod is sleeved with an electromagnet zero position holding spring and a spring washer. One end of the upper driving rod is connected to the rotating shaft of the rotating electromagnet, and the other end of the upper driving rod is clamped and arranged on the spring holding rod. And between the spring washer and the spring retainer, the upper driving rod can slide on the spring retaining rod. One end of the upper lever connected to the rotating shaft of the rotating electromagnet is set to an elliptical outer contour, the upper end of the lower shift fork is engaged with the oval outer contour, and the lower end of the lower shift fork is connected to the 2D piston of the valve body module.

Specifically, the toggle head of the lower half of the upper shift lever is oval, and the upper half of the lower shift fork is a U-shaped fork with an upward opening. The toggle head of the upper shift lever is inserted in the U-shaped fork of the lower shift fork, and the rotating electromagnetic The iron rotating shaft is fixedly connected with the upper lever to drive the upper lever to drive the lower fork to rotate, and the lower end of the lower fork is connected to the 2D piston of the valve body module to drive the 2D piston to rotate synchronously; the top of the upper lever can slide It is arranged on the spring holding rod, and one end of the spring holding rod is sheathed with an electromagnet zero position holding spring that obliquely presses the upper shift rod against the lower shift fork. In order to improve the working stability of the direct-acting 2D electro-hydraulic pressure servo valve and balance the inertial force, it is necessary to coincide the center of gravity of the upper lever 15 and the sixth screw 14 with the center of the rotating shaft of the rotary electromagnet 5, and the center of the 2D piston 31 The center coincides with the center of gravity of the lower shift fork 19 and the eighth screw 21.

The electromechanical converter module includes a rotating electromagnet, a connecting plate and an electromagnet protective cover that cooperate with each other. The rotating electromagnet is located at the upper end of the valve body 3. The rotating electromagnet is connected to the connecting plate 7 through the third screw 6. The electromagnet protective cover passes through The second screw 4 links to each other with the connecting plate 7, and the box cover 26 is connected to the electromagnet protective cover by the fifth screw 13 simultaneously.

The displacement sensor module includes an LVDT displacement sensor, whose function is to monitor the axial displacement of the 2D piston in real time and form a closed-loop feedback with the electric signal of the rotating electromagnet. The sensor mandrel 22 of the LVDT displacement sensor is fixedly connected with the 2D piston 31 through the threaded connecting rod 20, and is kept at the middle position of the inner hole of the LVDT displacement sensor 23 to improve its accuracy. The sensor bracket 24 is arranged on the connecting plate, and the LVDT displacement sensor 23 and the sensor bracket 24 adopt an interference fit to prevent axial sliding between the sensor and the sensor bracket when the pressure servo valve is transported or shaken, which affects its displacement detection precision.

The working principle of this example is as follows: as shown in Figure 6, when the rotating electromagnet 5 is not powered, the upper end of the upper shift lever 15, which is fixedly connected to the rotating shaft of the rotating electromagnet, is tightened under the action of the electromagnet zero position holding spring 9. Leaning against the shoulder of the spring holding rod 8, the lower shift fork 19 remains stationary, so that the 2D piston 31 is at zero position (the two sensitive chambers on the left and right of the 2D piston are in a force-balanced state). At the initial moment, the oil inlet P port at the shoulder of the left end of the spool and the control port A are blocked. If P and A are connected, the pressure oil enters the inner hole of the spool and then enters the sensitive chamber on the left side of the spool, generating a push The force of the spool moving to the right, at this time the channel between the P port and the A port is closed, and the spool is always in the right position. When the one-way rotating electromagnet 5 passes a positive current, the upper lever 15 is rotated counterclockwise by the external torque (viewed from right to left along the connecting plate), driving the lower shift fork 19 to rotate clockwise, and at the same time driving the 2D piston to rotate clockwise , so that the overlapping area of the low-pressure hole c and the damping chute becomes larger, the overlapping area of the high-pressure hole b and the damping chute becomes smaller, the pressure of the left sensitive chamber f decreases accordingly, while the pressure of the right sensitive chamber remains unchanged, and the 2D piston 31 is on the left and right The sensitive chamber moves to the left under the action of the pressure difference. During the process of moving to the left, the overlapping area of the low-pressure hole c and the damping chute becomes smaller, and the overlapping area of the high-pressure hole b and the damping chute becomes larger, and the pressure in the left sensitive chamber gradually increases. In addition, after the spring 34 is pressed, it produces a rightward reaction force to the 2D piston 31, and the 2D piston stops at a new equilibrium position; the force generated by the spring 34 directly acts on the right end of the spool 39, causing the spool to move to the left , at this time, port P is connected to port A, and port A is also connected to port T. Through the flow continuity equation, it can be known that the pressure change of port A can be controlled by changing the opening between P and A; the LVDT displacement sensor monitors the 2D piston in real time The axial displacement of 31 is fed back to the one-way rotating electromagnet to form a closed-loop feedback to precisely control the displacement of 2D piston 31, thereby adjusting the displacement of spool 39 in real time to achieve the purpose of controlling the constant pressure of A port.

The above-mentioned specific embodiments are used to explain the utility model, rather than to limit the utility model. Within the spirit of the utility model and the protection scope of the claims, any modification and change made to the utility model fall into the scope of the utility model. protected range.

Claims (9)

1. The direct-acting 2D electro-hydraulic pressure servo valve is characterized in that it consists of a valve body module, an electromechanical converter module, a transmission mechanism module and a displacement sensor module. The displacement sensor module cooperates with the valve body module, and the electromechanical converter module The transmission mechanism module cooperates with the valve body module; the displacement sensor module real-time monitors the displacement of the 2D piston in the valve body module and the electric signal of the rotating electromagnet of the electromechanical converter module forms a closed-loop feedback. 2. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 1, wherein the valve body module includes a valve core, a 2D piston, a spring and a valve body, the 2D piston is arranged on the right side of the valve body, and the valve body The core is set on the left side of the valve body, and the 2D piston has two movement directions of rotation and axial sliding in the valve body; one end of the 2D piston is provided with a shoulder, and a pair of high-pressure holes and a pair of low-pressure holes are arranged on the shoulder. A pair of high-pressure holes communicate with the oil inlet P port, and a pair of low-pressure holes communicate with the oil outlet T port; the inner hole wall of the cylinder in the valve body is symmetrically opened with a pair of damping chute matching the shoulder of the 2D piston, and the 2D piston The left sensitive chamber and the right sensitive chamber are formed between the shoulder of the cylinder and the concentric ring on the right side of the 2D piston. The 2D piston is installed in the cylinder. A pair of high pressure holes and a pair of low pressure holes on the shoulder of the 2D piston It intersects with a pair of damping chute to form four small openings in series to form a half-bridge of hydraulic resistance, which controls the pressure change of the left sensitive chamber, and the right sensitive chamber is connected to the oil inlet P port for high pressure, and the pressure of the left and right sensitive chambers is controlled Based on the hydraulic resistance half bridge, the pressure difference generated drives the 2D piston to move axially; the spool is provided with a left end shoulder, a right end shoulder and a middle shoulder, and the left end shoulder of the spool corresponds to the oil inlet P port. The middle shoulder corresponds to the control A port, the right end shoulder corresponds to the oil outlet T port, the left end shoulder, the right end shoulder and the middle shoulder are slidably fitted with the inner hole of the valve body; there is a valve between the valve core and the 2D piston The left gasket and the right gasket, the spring is set between the left gasket and the right gasket, the right end of the valve core is in contact with the right gasket through the steel ball, the left end of the 2D piston is in contact with the left gasket through the steel ball, and the 2D piston is in contact with the left gasket. The axial movement can be converted into the axial movement of the spool through the spring. 3. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 1, characterized in that the electromechanical converter module includes a rotating electromagnet, a connecting plate and an electromagnet protective cover that cooperate with each other; the transmission mechanism module It includes a spring retaining rod, an electromagnet zero position retaining spring, a spring washer, a spring retainer, an upper shift lever and a lower shift fork. The pole is socketed with an electromagnet zero-position holding spring and a spring washer. One end of the upper lever is connected to the rotating shaft of the rotating electromagnet. Between them, the upper shift lever can slide on the spring holding rod; one end of the upper shift lever connected to the rotation shaft of the rotating electromagnet is set to an elliptical outer contour, the upper end of the lower shift fork is engaged with the elliptical outer contour, and the lower shift fork The lower end is connected to the 2D piston of the valve body module. 4. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 1, wherein the displacement sensor module comprises a LVDT displacement sensor, and the sensor mandrel of the LVDT displacement sensor is connected to the 2D piston of the valve body module through a threaded connecting rod connected. 5. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 2, characterized in that a valve sleeve is arranged at the left end of the valve body, the valve core is installed in the valve sleeve, and an interference fit is installed at the right end of the valve core. The limit pin that limits the radial rotation of the spool slides in the U-shaped groove of the valve sleeve. 6. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 2, characterized in that an end cover is provided on one side of the valve body, and a box cover is provided on the other side of the valve body. 7. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 5, characterized in that the left end surface of the spool is configured as a disc-shaped structure, and when the spool moves left and right, the disc-shaped structure of the spool is in line with the A squeeze oil film is formed between the valve body and the valve sleeve. 8. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 3, characterized in that the upper end of the lower shift fork is a U-shaped fork with an upward opening, and the U-shaped fork is engaged with the elliptical outer contour. 9. The direct-acting 2D electro-hydraulic pressure servo valve according to claim 4, characterized in that the LVDT displacement sensor is installed on a sensor bracket.