A digital servo valve

Abstract

The present invention discloses a digital servo valve, which relates to the technical field of servo valves and is primarily used to address the problems of poor contamination resistance of nozzle baffle servo valves and mechanical backlash in 2D digital valves. Its main structure is as follows: a pilot valve core sleeve is connected to a rotatable sleeve on the outer wall of the pilot valve core between the connecting sleeve and the sealing end cover, and a damping groove is provided on the inner wall of the pilot valve core sleeve. An oil inlet hole, a valve core damping hole a, and a valve core damping hole b corresponding to the damping groove are provided on the outer wall of the pilot valve core, and the valve core damping hole a and valve core damping hole b are arranged on opposite sides of the oil inlet hole; the oil inlet hole is connected to the oil inlet chamber, the valve core damping hole a is connected to the sensitive chamber a, and the valve core damping hole b is connected to the sensitive chamber b; and the damping grooves on the opposite sides of the valve core damping hole a and valve core damping hole b are respectively provided with valve core sleeve damping tubes a and valve core sleeve damping tubes b, which are connected to the oil return system. The present invention provides a digital servo valve with strong contamination resistance and can address the mechanical backlash problem of 2D digital valves.

Description

Technical Field

[0001] The present invention relates to the technical field of servo valves, and in particular to a digital servo valve. Background Art

[0002] High-flow servo valves typically have a multi-stage structure. To increase servo valve flow, nozzle-flapper valves with better dynamic response are often used both domestically and internationally to achieve high flow. However, nozzle-flapper servo valves have poor contamination resistance—they require oil filtration accuracy below 5 microns, operate in demanding environments, and have high maintenance costs.

[0003] The 2D digital valve currently being researched in China utilizes a damping bridge. A digital servo motor provides a given angle signal, mechanically changing the damping. This damping change causes a pressure change, which in turn drives the valve core to move. During the valve core's displacement, the passive angle along the bow shape acts as damping negative feedback. This damping change causes a pressure change, and the valve core stops moving when the pressures on both ends of the valve core are balanced. The entire valve core opening, or valve flow, is linearly proportional to the valve's specified signal, and the proportional coefficient is linearly related to the lever arm, gear reduction ratio, and bow coefficient (helix angle).

[0004] However, the 2D digital valve still has certain disadvantages, namely, there is gear backlash in its lever arm, uncertainty in the zero position, and creeping phenomenon. Summary of the Invention

[0005] The object of the present invention is to provide a digital servo valve which has a strong anti-pollution capability and can solve the mechanical backlash problem of a 2D digital valve.

[0006] The technical solution of the present invention for solving the above technical problems is: a digital servo valve, comprising a servo motor, a connecting sleeve and a valve body coaxially connected in sequence, the side wall of the valve body is provided with an oil return port a, an oil outlet port a, an oil inlet port, an oil outlet port b and an oil return port b arranged in sequence along its axial direction, a pilot valve core is coaxially fixedly provided in the valve body with a clearance fit between the outer wall and the inner wall of the valve body, the outer wall of the pilot valve core on the opposite sides of the oil return port a and the oil return port b are fixedly sleeved with a sealing end cover, and the sealing end cover is sealed with the outer wall of the pilot valve core and the inner wall of the valve body; a main valve core tube is sleeved on the pilot valve core between the two sealing end covers, which can move along its axial direction and is slidably and sealedly fitted with the outer wall of the pilot valve core and the inner wall of the valve body, the two ends of the main valve core tube respectively form a sensitive cavity a and a sensitive cavity b with the two sealing end covers, and the outer wall of the main valve core tube is provided with an annular groove connected with the oil inlet to form an oil inlet cavity;

[0007] A pilot valve core sleeve is sleeved on the outer wall of the pilot valve core between the connecting sleeve and the sealing end cover, which can rotate axially and rotate and seal with the outer wall of the pilot valve core, and a damping groove arranged around its axis is provided on the inner wall of the pilot valve core sleeve, and an oil inlet hole, a valve core damping hole a and a valve core damping hole b corresponding to the damping groove are provided on the outer wall of the pilot valve core, and the valve core damping hole a and the valve core damping hole b are relatively arranged on both sides of the oil inlet hole; the oil inlet hole is connected with the oil inlet chamber through a high-pressure channel arranged in the pilot valve core, the valve core damping hole a is connected with the sensitive chamber a through a connecting channel arranged in the pilot valve core, and the valve core damping hole b is connected with the sensitive chamber b through a connecting channel arranged in the pilot valve core; the damping grooves on the opposite sides of the valve core damping hole a and the valve core damping hole b are respectively provided with a valve core sleeve damping tube a and a valve core sleeve damping tube b which are connected with both the return oil port a and the return oil port b.

[0008] As a further improvement of the present invention, the outer wall axis of the pilot valve core sleeve away from the pilot valve core is key-connected to the servo motor output end through a transmission shaft. The transmission shaft passes through the bottom surface of the connecting sleeve and a sealing ring and a rolling bearing sleeved on the transmission shaft are provided between the transmission shaft and the connecting sleeve.

[0009] As a further improvement of the present invention, a limit pin is fixedly installed on the end face of the pilot valve core close to the bottom face of the pilot valve core sleeve, and a limit hole extending along its rotation direction is provided on the bottom face of the pilot valve core sleeve. The limit pin is movably inserted in the limit hole at one end away from the pilot valve core.

[0010] As a further improvement of the present invention, the outer wall of the main valve core tube is further provided with two annular grooves, one of which is connected to the oil return port a to form an oil return chamber a, and the other annular groove is connected to the oil return port b to form an oil return chamber b; the valve core sleeve damping tube a and the valve core sleeve damping tube b are both connected to the oil return port a and the oil return port b through an oil return channel arranged in the valve body.

[0011] As a further improvement of the present invention, a pressure reducing valve is installed on the pilot valve core, the inlet end of which is connected to the high-pressure channel and the outlet end of which is connected to the oil inlet hole.

[0012] As a further improvement of the present invention, a pressure plate is sleeved on the end of the pilot valve core away from the pilot valve core sleeve, and the pressure plate is arranged on the side of the sealing end cover away from the pilot valve core sleeve, and a needle bearing sleeved on the pilot valve core is provided between the pressure plate and the sealing end cover arranged close to the pressure plate, and a locking nut is threadedly connected to the pilot valve core on the side of the pressure plate away from the sealing end cover.

[0013] As a further improvement of the present invention, a centering spring sleeved on the pilot valve core is provided between the sealing end cover and the end face of the main valve core tube, and both ends of the centering spring are in tight contact with the sealing end cover and the end face of the main valve core tube respectively.

[0014] As a further improvement of the present invention, a needle roller bearing arranged around the axis of the pilot valve core sleeve is provided between the pilot valve core sleeve and the valve body.

[0015] As a further improvement of the present invention, a sealing ring arranged around the axis of the sealing end cover is provided between the sealing end cover and the pilot valve core, and between the sealing end cover and the valve body.

[0016] As a further improvement of the present invention, the oil inlet chamber and the high-pressure channel are communicated with each other through a main valve core hole provided on the side wall of the main valve core tube.

[0017] Beneficial effects

[0018] Compared with the prior art, the advantages of the digital servo valve of the present invention are:

[0019] 1. After the digital servo valve is connected to the oil circuit, part of the high-pressure oil in the oil inlet chamber flows out from the oil inlet hole through the high-pressure oil channel and enters the valve core damping hole a, valve core damping hole b, valve core sleeve damping tube a and valve core sleeve damping tube b respectively through the damping groove; among them, the valve core damping hole a and valve core damping hole b are symmetrically arranged on both sides of the oil inlet hole, and cooperate with the valve core sleeve damping tube a and valve core sleeve damping tube b which are also symmetrically arranged on both sides of the oil inlet hole in the initial state, so as to achieve the same pressure in the sensitive chamber a and the sensitive chamber b, thereby keeping the main valve core tube in the initial position and the oil outlet a and the oil outlet b both closed. Afterwards, when the oil outlet a needs to be opened, it is only necessary to drive the pilot valve core sleeve to rotate through the servo motor, so that the valve core sleeve damping tube a is close to the valve core damping hole a, and the valve core sleeve damping tube b is away from the valve core damping hole b, so that the pressure in the sensitive chamber a is lower than the pressure in the sensitive chamber b, thereby driving the main valve core tube to move, and then opening the oil outlet a. Conversely, when opening the oil outlet b, the principle is the same.

[0020] In this device, due to the uniform damping channel and constant pressure in the oil return system, the pressure in sensitive chamber a is linearly related to the spacing between the valve core damping orifice a and the valve core sleeve damping tube a, and the pressure in sensitive chamber b is linearly related to the spacing between the valve core damping orifice b and the valve core sleeve damping tube b. The relationship between the damping length and angle is linear, with the radius as the proportional coefficient. The angle is also linearly related to the servo motor pulse. Therefore, the digital control of the servo motor is linearly related to the pressure at both ends of the main valve core tube. The main valve core displacement or opening is also linearly related to the flow rate. Therefore, given a constant inlet and outlet pressure, the servo motor can directly generate a digital flow signal from the digital signal. This characteristic is not found in nozzle-flapper servo valves.

[0021] 2. Existing nozzle flapper valves and 2D digital valves primarily achieve oil outlet switching by blocking one of the valve core damping orifices or by varying the size of the valve core damping orifices. This system utilizes nozzle switching in the nozzle flapper valve and orifice switching in the 2D digital valve to obtain a pressure signal. Consequently, existing technologies place high demands on oil viscosity and cleanliness, otherwise clogging and malfunction are likely to occur. This digital servo valve, on the other hand, adjusts the pressure of the corresponding valve core damping orifice by adjusting the distance between the valve core damping tube and the oil inlet. This system requires relatively low oil requirements and exhibits strong contamination resistance.

[0022] 3. This digital servo valve uses a rotary disc coupling mode, which is a rotary disc coupling mode between the pilot valve core sleeve and the pilot valve core, rather than a mechanical connection with a thread feedback mode. This mode eliminates the problems of thread mode getting stuck at the extreme position and mechanical backlash.

[0023] The present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, which are used to illustrate embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is one of the axial cross-sectional views of the present invention;

[0026] Figure 2 This is the second axial cross-sectional view of the present invention;

[0027] Figure 3 A three-dimensional diagram of the main valve core tube;

[0028] Figure 4 It is a three-dimensional diagram of the pilot valve core sleeve;

[0029] Figure 5 This is the axial front view of the pilot valve core sleeve;

[0030] Figure 6 It is a three-dimensional diagram of the pilot valve core;

[0031] Figure 7 This is one of the cross-sectional views of the pilot valve core;

[0032] Figure 8 This is the second cross-sectional view of the pilot valve core;

[0033] Figure 9 It is a schematic diagram of the cooperation between the pilot valve core sleeve and the pilot valve core.

[0034] Among them: 1-servo motor; 2-connecting sleeve; 3-sealing ring; 4-rolling bearing; 5-pressure reducing valve; 6-needle bearing; 7-centering spring; 8-sealing end cover; 9-locking nut; 10-pressing plate; 11-main valve core tube; 12-valve body; 13-pilot valve core; 14-pilot valve core sleeve; 15-sensitive chamber a; 16-return oil port a; 17-return oil chamber a; 18-return oil channel; 19-return oil port b; 20-return Oil chamber b; 21-sensitive chamber b; 22-working chamber a; 23-oil inlet chamber; 24-working chamber b; 25-limit pin; 26-limit hole; 27-damping groove; 28-valve core damping tube a; 29-valve core damping tube b; 30-high-pressure channel; 31-valve core damping hole a; 32-valve core damping hole b; 33-oil inlet hole; 34-main valve core hole; 35-oil outlet a; 36-oil outlet b; 37-oil inlet. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; of course, they may also refer to mechanical connections or electrical connections; in addition, they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0037] Embodiments of the present invention will now be described with reference to the accompanying drawings.

[0038] Example

[0039] The specific embodiments of the present invention are as follows Figure 1-9 As shown, a digital servo valve comprises a servo motor 1, a connecting sleeve 2, and a valve body 12, all coaxially connected. Of course, in actual production, a stepper motor can also be used instead of the servo motor 1. The sidewall of the valve body 12 is provided with an oil return port a16, an oil outlet port a35, an oil inlet port 37, an oil outlet port b36, and an oil return port b19, arranged in sequence along its axial direction.

[0040] A pilot valve core 13 is coaxially fixed within the valve body 12, its outer wall forming a clearance fit with the inner wall of the valve body 12. Sealing end caps 8 are fixedly mounted on the outer walls of the pilot valve core 13 on opposite sides of the oil return port a16 and the oil return port b19, and the sealing end caps 8 are in a sealed fit with both the outer wall of the pilot valve core 13 and the inner wall of the valve body 12. Simultaneously, a main valve core tube 11 is mounted on the pilot valve core 13 between the two sealing end caps 8, capable of axial movement and in a sliding, sealing fit with both the outer wall of the pilot valve core 13 and the inner wall of the valve body 12. The two ends of the main valve core tube 11 form a sensitive cavity a15 and a sensitive cavity b21, respectively, with the two sealing end caps 8. An annular groove is provided on the outer wall of the main valve core tube 11, which communicates with the oil inlet 37 to form the oil inlet cavity 23. By changing the pressure in the sensitive chamber a15 and the sensitive chamber b21 to form a pressure difference, the main valve core tube 11 can be driven to move axially toward the side with lower pressure, thereby connecting the oil inlet chamber 23 with the oil outlet a35 or the oil outlet b36, and then outputting the pressurized oil from the oil outlet a35 or the oil outlet b36.

[0041] To create a pressure differential by varying the pressures within the sensitive chambers a15 and b21, a pilot valve sleeve 14 is sleeved onto the outer wall of the pilot valve core 13 between the connecting sleeve 2 and the sealing end cap 8. The sleeve is axially rotatable and engages in a rotationally sealed manner with the outer wall of the pilot valve core 13. The inner wall of the pilot valve sleeve 14 is provided with a damping groove 27 arranged around its axis. The damping groove 27 has a uniform inner diameter. Furthermore, the outer wall of the pilot valve core 13 is provided with an oil inlet hole 33, corresponding to the damping groove 27, as well as a valve core damping hole a31 and a valve core damping hole b32. The valve core damping holes a31 and b32 have the same inner diameter and are positioned on opposite sides of the oil inlet hole 33. The oil inlet hole 33 communicates with the oil inlet chamber 23 via a high-pressure passage 30 provided within the pilot valve core 13. The valve core damping orifice a31 communicates with the sensitive chamber a15 via a communication passage provided within the pilot valve core 13. The valve core damping orifice b32 communicates with the sensitive chamber b21 via a communication passage provided within the pilot valve core 13. The damping groove 27, located opposite the valve core damping orifice a31 and valve core damping orifice b32, respectively, is provided with a valve core sleeve damping tube a28 and a valve core sleeve damping tube b29, which communicate with both the oil return port a16 and the oil return port b19. These valve core sleeve damping tubes a28 and b29 have the same inner diameter.

[0042] In this embodiment, to improve damping sensitivity, the oil inlet hole 33, valve core damping hole a31, valve core damping hole b32, or valve core sleeve damping tube a28, and valve core sleeve damping tube b29 are preferably as deep and wide as possible. Furthermore, the damping groove 27 is preferably as thin and small as possible. Furthermore, the oil inlet chamber 23 communicates with the high-pressure passage 30 via a main valve core hole 34 provided on the sidewall of the main valve core tube 11. Furthermore, a pressure reducing valve 5 is mounted on the pilot valve core 13, with its inlet end communicating with the high-pressure passage 30 and its outlet end communicating with the oil inlet hole 33.

[0043] During operation, pressurized oil flows through the oil inlet 37, through the main valve core hole 34, and into the high-pressure passage 30 of the pilot valve core 13. After being reduced in pressure by the pressure reducing valve 5, it enters the damping groove 27 through the oil inlet hole 33. A portion of the high-pressure oil passes through the damping groove 27, through the valve core damping holes a31 and b32, and enters the sensitive chambers a15 and b21, respectively. Meanwhile, another portion of the high-pressure oil passes through the damping groove 27, through the valve core housing damping tubes a28 and b29, and returns to the oil return ports a16 and b19. In this embodiment, the oil inlet chamber 23 is connected to the oil inlet 37, the working chamber a22 is connected to the oil outlet a35, and the working chamber b24 is connected to the oil outlet b36.

[0044] Among them, the oil inlet hole 33 is the highest pressure point. After being restricted by the damping groove 27, the pressure at the valve core sleeve damping tube a28 and the valve core sleeve damping tube b29 is the lowest, but the pressure remains unchanged. As a result, a symmetrical pressure linear band is formed on both sides from the highest point to the lowest point of the return oil port. The pressure is high near the highest pressure point and low far from the highest pressure point. At this time, the pressure signal is taken on both sides of the highest pressure point through the valve core damping hole a31 and the valve core damping hole b32 to the sensitive cavity a15 and the sensitive cavity b21 on both sides of the valve core. When the two pressure points are symmetrical based on the highest pressure point, the pressure in the sensitive cavity a15 and the sensitive cavity b21 are the same, there is no pressure difference at both ends of the main valve core tube 11, the valve core does not move, and the valve is closed.

[0045] When the servo motor 1 rotates the pilot valve sleeve 14, the sleeve damping tube a28 approaches the spool damping orifice a31 and the sleeve damping tube b29 moves away from the spool damping orifice b32. Based on the linear relationship between distance and pressure, the pressure in the spool damping orifice a31 decreases, while the pressure in the spool damping orifice b32 increases. This lowers the pressure in the sensitive chamber a15 to below that in the sensitive chamber b21, driving the main valve sleeve 11 toward the sensitive chamber a15, thereby connecting the oil inlet chamber 23 with the working chamber a22 and opening the oil outlet a3. Conversely, when opening the oil outlet b36, the servo motor 1 drives the pilot valve sleeve 14 in the opposite direction, moving the sleeve damping tube a28 away from the spool damping orifice a31 and the sleeve damping tube b29 toward the spool damping orifice b32. The remaining principles remain the same. It should be noted that: when the servo motor 1 stops rotating, the pilot valve core 13 is reset to the same angle under the action of the external feedback device, the pressure in the valve core damping hole a31 and the valve core damping hole b32 will be restored to a pressure balanced state, and the main valve core tube 11 will be reset to the middle position.

[0046] In this device, because the damping channel is uniform and the pressure in the oil return system is constant, the pressure in the sensitive chamber a15 is linearly related to the spacing between the valve core damping orifice a31 and the valve core sleeve damping tube a28, and the pressure in the sensitive chamber b21 is linearly related to the spacing between the valve core damping orifice b32 and the valve core sleeve damping tube b29. The damping length and angle are linearly related, with the radius of the pilot valve core sleeve 14 as the proportional coefficient. The angle is also linearly related to the pulse of the servo motor 1. Therefore, the digital control of the servo motor 1 is linearly related to the pressure at both ends of the main valve core tube 11. Furthermore, because the displacement or opening of the main valve core tube 11 of this valve is linearly related to the flow rate, the servo motor 1 can directly generate a digital flow signal from the digital signal when the valve inlet and outlet pressures are constant. This characteristic is not found in nozzle flapper servo valves.

[0047] Furthermore, existing nozzle flapper valves and 2D digital valves primarily achieve oil outlet switching by blocking one of the valve core damping orifices or by varying the size of the valve core damping orifices. This facilitates nozzle switching in the nozzle flapper valve and orifice switching in the 2D digital valve to obtain a pressure signal. Consequently, existing technologies place high demands on oil viscosity and cleanliness, otherwise clogging and malfunction are likely to occur. This digital servo valve, on the other hand, adjusts the pressure of the corresponding valve core damping orifice by adjusting the distance between the valve core damping tube and the oil inlet hole 33. This reduces oil requirements and offers strong contamination resistance.

[0048] Furthermore, this digital servo valve utilizes a rotary disk coupling mechanism—a rotary disk coupling mechanism between the pilot valve core sleeve 14 and the pilot valve core 13—rather than the mechanical coupling mechanism of the threaded feedback mechanism used in existing 2D digital valves. This mechanism eliminates the issues of threaded coupling becoming stuck at extreme positions and mechanical backlash.

[0049] In this digital servo valve, to enable the servo motor 1 to rotate the pilot valve core sleeve 14, the outer axis of the pilot valve core sleeve 14, away from the pilot valve core 13, is keyed to the output end of the servo motor 1 via a drive shaft. The drive shaft extends through the bottom surface of the connecting sleeve 2, and a sealing ring 3 and a rolling bearing 4 are located between the drive shaft and the connecting sleeve 2. The sealing ring 3 prevents direct contact between the oil and the servo motor 1, while the rolling bearing 4 ensures smooth rotation of the pilot valve core sleeve 14.

[0050] At the same time, since in this digital servo valve, the valve core sleeve damping tube a28 and the valve core sleeve damping tube b29 cannot rotate between the oil inlet hole 33 and the valve core damping hole a31 and the valve core damping hole b32, it is necessary to limit the rotation angle of the pilot valve core sleeve 14. Therefore, a limit pin 25 is fixedly inserted on the end face of the pilot valve core 13 close to the bottom surface of the pilot valve core sleeve 14, and a limit hole 26 extending along the rotation direction of the pilot valve core sleeve 14 is provided on the bottom surface of the pilot valve core sleeve 14. The limit pin 25 is movably inserted into the limit hole 26 at one end away from the pilot valve core 13. Through the movable cooperation between the limit pin 25 and the limit hole 26, the rotation angle of the pilot valve core sleeve 14 can be limited, thereby ensuring the normal operation of the digital servo valve.

[0051] In this embodiment, the outer wall of the main valve core tube 11 is further provided with two annular grooves. One of these annular grooves connects to the oil return port a16 to form an oil return chamber a17, and the other connects to the oil return port b19 to form an oil return chamber b20. The valve core sleeve damping tubes a28 and b29 both connect to the oil return ports a16 and b19 via an oil return passage 18 disposed within the valve body 12. This design is intended to accommodate situations where the oil outlets a35 and b36 of this digital servo valve are connected to the oil inlet and outlet channels of the same load, respectively. In this case, the digital servo valve can meet the requirements for forward / reverse oil circulation within the load.

[0052] Specifically, when using this digital servo valve in this situation, its oil outlet a35 and oil outlet b36 must be connected to the oil inlet and oil outlet channels of the same load, respectively, and its oil return ports a16 and oil return ports b19 must be connected to the inlet of the oil return tank, respectively. During operation, when oil outlet a35 opens with the movement of the main valve core tube 11, the oil inlet chamber 23 connects with the working chamber a22. Simultaneously, the oil return chamber a17 disconnects from the working chamber a22, but the oil return chamber b19 connects with the working chamber b20. In this situation, pressurized oil is input into the load from the load's oil inlet / outlet channels and output from the oil outlet / inlet channels to oil outlet b36. At this point, because the oil return chamber b19 is connected to the working chamber b20, the oil can be returned to the oil tank via the oil return port b19, thereby achieving the required oil circulation within the load. Similarly, when the oil outlet b36 is opened as the main valve core tube 11 moves, the oil circulation in the load can also be achieved, but the oil in the load flows in the reverse direction.

[0053] At the same time, a pressure plate 10 is sleeved onto the end of the pilot valve core 13 that is away from the pilot valve core sleeve 14. Pressure plate 10 is located on the side of the sealing end cover 8 that is away from the pilot valve core sleeve 14. A needle roller bearing 6, which is sleeved onto the pilot valve core 13, is located between pressure plate 10 and the sealing end cover 8 that is located near pressure plate 10. A locking nut 9 is threadedly connected to the pilot valve core 13 on the side of pressure plate 10 that is away from the sealing end cover 8. By turning locking nut 9, pressure plate 10 is locked, preventing the sealing end cover 8 from loosening and affecting the stability of the entire system.

[0054] Furthermore, due to the length difference between the communication channel connecting the valve core damping orifice a31 and the sensitive chamber a15, and the communication channel connecting the valve core damping orifice b32 and the sensitive chamber b21, in the initial state, to balance the pressure difference within the sensitive chambers a15 and b21 caused by this length difference, a centering spring 7, which is sleeved on the pilot valve core 13, is installed between the sealing end cap 8 and the end face of the main valve core tube 11. The ends of the centering spring 7 are in close contact with the sealing end cap 8 and the end face of the main valve core tube 11, respectively.

[0055] It should be noted that:

[0056] To ensure the normal operation of the entire digital servo valve, a needle bearing 6 is provided between the pilot valve core sleeve 14 and the valve body 12, which is arranged around the axis of the pilot valve core sleeve 14. A sealing ring 3 is provided between the sealing end cover 8 and the pilot valve core 13, and between the sealing end cover 8 and the valve body 12, which is arranged around the axis of the sealing end cover 8.

[0057] The present invention has been described above in conjunction with the best embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations based on the essence of the present invention.

Claims

1. A digital servo valve, comprising a servo motor (1), a connecting sleeve (2) and a valve body (12) coaxially connected in sequence, wherein the side wall of the valve body (12) is provided with an oil return port a (16), an oil outlet port a (35), an oil inlet port (37), an oil outlet port b (36) and an oil return port b (19) arranged in sequence along its axial direction, characterized in that: A pilot valve core (13) is coaxially fixed in the valve body (12), the outer wall of which is in clearance fit with the inner wall of the valve body (12); a sealing end cover (8) is fixedly sleeved on the outer wall of the pilot valve core (13) on the opposite side of the oil return port a (16) and the oil return port b (19), and the sealing end cover (8) is in sealing fit with the outer wall of the pilot valve core (13) and the inner wall of the valve body (12); a main valve core tube (11) is sleeved on the pilot valve core (13) between the two sealing end covers (8), which can move along its axial direction and is in sliding sealing fit with the outer wall of the pilot valve core (13) and the inner wall of the valve body (12); the two ends of the main valve core tube (11) respectively form a sensitive cavity a (15) and a sensitive cavity b (21) with the two sealing end covers (8), and the outer wall of the main valve core tube (11) is provided with an annular groove connected with the oil inlet (37) to form an oil inlet cavity (23); A pilot valve core sleeve (14) is sleeved on the outer wall of the pilot valve core (13) between the connecting sleeve (2) and the sealing end cover (8), and the pilot valve core sleeve (14) is capable of axial rotation and is in rotation and sealing cooperation with the outer wall of the pilot valve core (13). The inner wall of the pilot valve core sleeve (14) is provided with a damping groove (27) arranged around its axis. The outer wall of the pilot valve core (13) is provided with an oil inlet hole (33) corresponding to the damping groove (27), a valve core damping hole a (31) and a valve core damping hole b (32), and the valve core damping hole a (31) and the valve core damping hole b (32) are relatively arranged on both sides of the oil inlet hole (33); the oil inlet hole (33) ) is communicated with the oil inlet chamber (23) through a high-pressure channel (30) provided in the pilot valve core (13); the valve core damping hole a (31) is communicated with the sensitive chamber a (15) through a communication channel provided in the pilot valve core (13); the valve core damping hole b (32) is communicated with the sensitive chamber b (21) through a communication channel provided in the pilot valve core (13); and the valve core damping hole a (31) and the valve core damping hole b (32) are respectively provided with a valve core sleeve damping tube a (28) and a valve core sleeve damping tube b (29) which are communicated with both the oil return port a (16) and the oil return port b (19) on the damping groove (27) on the opposite sides of the valve core damping hole a (31) and the valve core damping hole b (32).

2. The digital servo valve according to claim 1, characterized in that: The outer wall axis of the pilot valve core sleeve (14) away from the pilot valve core (13) is key-connected to the output end of the servo motor (1) via a transmission shaft. The transmission shaft passes through the bottom surface of the connecting sleeve (2), and a sealing ring (3) and a rolling bearing (4) sleeved on the transmission shaft are provided between the transmission shaft and the connecting sleeve (2).

3. The digital servo valve according to claim 1 or 2, characterized in that: A limiting pin (25) is fixedly inserted on the end surface of the pilot valve core (13) close to the bottom surface of the pilot valve core sleeve (14), and a limiting hole (26) extending along the rotation direction of the pilot valve core sleeve (14) is provided on the bottom surface of the pilot valve core sleeve (14). The limiting pin (25) is movably inserted into the limiting hole (26) at one end away from the pilot valve core (13).

4. The digital servo valve according to claim 1, characterized in that: The outer wall of the main valve core tube (11) is further provided with two annular grooves, one of which is connected to the oil return port a (16) to form an oil return chamber a (17), and the other annular groove is connected to the oil return port b (19) to form an oil return chamber b (20); the valve core sleeve damping tube a (28) and the valve core sleeve damping tube b (29) are both connected to the oil return port a (16) and the oil return port b (19) through an oil return channel (18) provided in the valve body (12).

5. The digital servo valve according to claim 1, characterized in that: The pilot valve core (13) is provided with a pressure reducing valve (5) whose inlet end is connected to the high-pressure channel (30) and whose outlet end is connected to the oil inlet hole (33).

6. The digital servo valve according to claim 1, characterized in that: A pressure plate (10) is sleeved on one end of the pilot valve core (13) away from the pilot valve core sleeve (14), and the pressure plate (10) is arranged on the side of the sealing end cover (8) away from the pilot valve core sleeve (14), and a needle bearing (6) sleeved on the pilot valve core (13) is provided between the pressure plate (10) and the sealing end cover (8) arranged close to the pressure plate (10), and a locking nut (9) is threadedly connected to the pilot valve core (13) on the side of the pressure plate (10) away from the sealing end cover (8).

7. The digital servo valve according to claim 1, characterized in that: A centering spring (7) sleeved on the pilot valve core (13) is provided between the sealing end cover (8) and the end surface of the main valve core tube (11), and the two ends of the centering spring (7) are respectively in tight contact with the sealing end cover (8) and the end surface of the main valve core tube (11).

8. The digital servo valve according to claim 1, characterized in that: A needle roller bearing (6) arranged around the axis of the pilot valve core sleeve (14) is provided between the pilot valve core sleeve (14) and the valve body (12).

9. The digital servo valve according to claim 1, characterized in that: A sealing ring (3) arranged around the axis of the sealing end cover (8) is provided between the sealing end cover (8) and the pilot valve core (13), and between the sealing end cover (8) and the valve body (12).

10. The digital servo valve according to claim 1, characterized in that: The oil inlet chamber (23) and the high-pressure channel (30) are communicated with each other through a main valve core hole (34) provided on the side wall of the main valve core tube (11).

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