Digital servo valve

Abstract

The invention discloses a digital servo valve, relates to the technical field of servo valves, and is mainly used for solving the problems that a nozzle baffle servo valve is poor in pollution resistance and a 2D digital valve has mechanical backlash. According to the main structure, a pilot valve element sleeve is sleeved on the outer wall of a pilot valve element between a connecting sleeve and a sealing end cover in a pivoted mode, a damping groove is formed in the inner wall of the pilot valve element sleeve, and an oil inlet hole, a valve element damping hole a and a valve element damping hole b corresponding to the damping groove are formed in the outer wall of the pilot valve element. The valve element damping hole a and the valve element damping hole b are oppositely formed in the two sides of the oil inlet hole. The oil inlet hole is communicated with the oil inlet cavity, the valve element damping hole a is communicated with the sensitive cavity a, and the valve element damping hole b is communicated with the sensitive cavity b; and a valve core sleeve damping pipe a and a valve core sleeve damping pipe b which are communicated with an oil return system are respectively arranged on the damping grooves on the opposite sides of the valve core damping hole a and the valve core damping hole b. The invention provides a digital servo valve. The digital servo valve is high in anti-pollution capacity and capable of solving the mechanical backlash problem of a 2D digital valve.

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] The servo valve with large flow rate is basically a multi-stage valve structure. In order to increase the flow rate of the servo valve, nozzle flapper valves with better dynamic response are often used at home and abroad to achieve large flow rate. However, the nozzle flapper servo valve has poor anti-pollution ability - it requires the oil filtration accuracy to be below 5 microns, and the use environment requirements are harsh, and the maintenance cost is very high.

[0003] The 2D digital valve currently being studied in China uses a damping bridge to mechanically change the damping by giving an angle signal through a digital servo motor. The damping change causes a pressure change, thereby pushing the valve core to produce an opening displacement. During the valve core displacement process, the passive angle along the bow shape changes as a damping negative feedback. The damping change causes a pressure change. When the pressure at both ends of the valve core is balanced, the valve core stops moving. The opening of the entire valve core or the valve flow is linearly proportional to the valve specified signal, and the proportional coefficient is linearly related to the force 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 force arm, there is uncertainty in the zero position, and there is a creeping phenomenon. Summary of the invention

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

[0006] The technical solution of the present invention to solve 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 with a clearance between the outer wall and the inner wall of the valve body coaxially fixedly arranged in the valve body, a sealing end cover is fixedly sleeved on the outer wall of the pilot valve core on the opposite side of the oil return port a and the oil return port b, 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 which can move along its axial direction and is in sliding and sealing cooperation with the outer wall of the pilot valve core and the inner wall of the valve body is sleeved on the pilot valve core between the two sealing end covers, 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 valve core sleeve damping tube a and valve core sleeve damping tube b which are connected with both the oil return port a and the oil return 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 inserted 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 also provided with two annular grooves, one of which is connected with the oil return port a to form an oil return chamber a, and the other annular groove is connected with 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 with 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, 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 surface of the main valve core tube, and both ends of the centering spring are respectively in tight contact with the sealing end cover and the end surface of the main valve core tube.

[0014] As a further improvement of the present invention, a needle 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 arranged on the side wall of the main valve core tube.

[0017] Beneficial Effects

[0018] Compared with the prior art, the advantages of a 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; wherein, 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 that the pressure in the sensitive chamber a and the sensitive chamber b can be the same, thereby keeping the main valve core tube in the initial position, and the oil outlet a and the oil outlet b are both closed. Afterwards, when it is necessary to open the oil outlet a, 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, since the damping channel is uniform and the pressure in the oil return system is fixed, the pressure in the sensitive chamber a is linearly related to the distance between the valve core damping hole a and the valve core sleeve damping tube a, and the pressure in the sensitive chamber b is linearly related to the distance between the valve core damping hole b and the valve core sleeve damping tube b; the relationship between the damping length and the angle is a linear relationship with the radius as the proportional coefficient; the angle and the pulse of the servo motor are linearly related. Therefore, the digital control of the servo motor is linearly related to the pressure at both ends of the main valve core tube; the displacement or opening of the main valve core and the flow rate can form a linear relationship, so when the inlet and outlet pressures of the valve are constant, the servo motor can directly obtain a digital flow signal through a digital signal, which is a feature that the nozzle flapper servo valve does not have.

[0021] 2. The existing nozzle flapper valve and 2D digital valve mainly obtain pressure signals by blocking one of the valve core damping holes or the valve core damping holes are of different sizes, and cooperate with the nozzle conversion of the nozzle flapper valve and the throttle hole conversion of the 2D digital valve to achieve the switching of the oil outlet. Therefore, the existing technology has high requirements on the viscosity and cleanliness of the oil, otherwise it is easy to get clogged and cause failure. The digital servo valve uses the distance adjustment between the valve core damping tube and the oil inlet hole to achieve the pressure adjustment of the corresponding valve core damping hole. It has relatively low requirements on the oil and strong anti-pollution ability.

[0022] 3. This digital servo valve proposes a rotary disk mode coupling - the pilot valve core sleeve and the pilot valve core are in a rotary disk coupling mode, rather than a mechanical connection in a thread feedback mode. This mode will not cause the thread mode to get stuck at the extreme position and the problem of 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0025] Figure 1 It 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 It 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 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] Fig. 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-pressure 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 purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work 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 clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; of course, it can also be a mechanical connection or an electrical connection; in addition, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to 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 which are coaxially connected in sequence. Of course, in the actual production process, a stepper motor can also be selected to replace the servo motor 1. The side wall 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 which are sequentially arranged along the axial direction thereof.

[0040] Among them, a pilot valve core 13 whose outer wall is in clearance with the inner wall of the valve body 12 is coaxially fixed in the valve body 12. The outer wall of the pilot valve core 13 on the opposite side of the oil return port a16 and the oil return port b19 is fixedly sleeved with a sealing end cover 8, and the sealing end cover 8 is in sealing cooperation with the outer wall of the pilot valve core 13 and the inner wall of the valve body 12. At the same time, the pilot valve core 13 between the two sealing end covers 8 is sleeved with a main valve core tube 11 that can move along its axial direction and is in sliding and sealing cooperation 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 a15 and a sensitive cavity b21 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. 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, so that the oil inlet chamber 23 is connected with the oil outlet a35 or the oil outlet b36, and the pressure oil is output from the oil outlet a35 or the oil outlet b36.

[0041] In order to change the pressure in the sensitive chamber a15 and the sensitive chamber b21 to form a pressure difference, 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, which can rotate axially and cooperate with the outer wall of the pilot valve core 13 in a rotating seal, and a damping groove 27 arranged around its axis is provided on the inner wall of the pilot valve core sleeve 14. The inner diameter of the damping groove 27 is uniform. In addition, an oil inlet hole 33, a valve core damping hole a31 and a valve core damping hole b32 corresponding to the damping groove 27 are provided on the outer wall of the pilot valve core 13. The valve core damping hole a31 and the valve core damping hole b32 have the same inner diameter and are relatively arranged on both sides of the oil inlet hole 33. The oil inlet hole 33 is connected to the oil inlet chamber 23 through the high pressure channel 30 provided in the pilot valve core 13, the valve core damping hole a31 is connected to the sensitive chamber a15 through the communication channel provided in the pilot valve core 13, and the valve core damping hole b32 is connected to the sensitive chamber b21 through the communication channel provided in the pilot valve core 13. The valve core sleeve damping tube a28 and the valve core sleeve damping tube b29 which are connected to the oil return port a16 and the oil return port b19 are respectively provided on the damping groove 27 on the opposite sides of the valve core damping hole a31 and the valve core damping hole b32, and the inner diameters of the valve core sleeve damping tube a28 and the valve core sleeve damping tube b29 are the same.

[0042] In this embodiment, in order to improve the damping sensitivity, the oil inlet hole 33, the valve core damping hole a31, the valve core damping hole b32 or the valve core sleeve damping tube a28, the valve core sleeve damping tube b29 should be as deep and wide as possible, and the damping groove 27 should be relatively thinner and smaller as possible. At the same time, the oil inlet chamber 23 is connected to the high-pressure channel 30 through the main valve core hole 34 set on the side wall of the main valve core tube 11. And the pilot valve core 13 is installed 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.

[0043] When in use, the pressure oil passes through the oil inlet 37, through the main valve core hole 34, into the high pressure channel 30 of the pilot valve core 13, and then enters the damping groove 27 through the oil inlet hole 33 after being reduced in pressure by the pressure reducing valve 5. A part of the high pressure oil passes through the damping groove 27 through the valve core damping hole a31 and the valve core damping hole b32 to enter the sensitive chamber a15 and the sensitive chamber b21 respectively. At the same time, another part of the high pressure oil passes through the damping groove 27 through the valve core sleeve damping tube a28 and the valve core sleeve damping tube b29 to return to the oil return port a16 and the oil return port 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 magnitude remains unchanged. Therefore, 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 chamber a15 and the sensitive chamber 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 chamber a15 and the sensitive chamber 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 drives the pilot valve core sleeve 14 to rotate, the valve core sleeve damping tube a28 is close to the valve core damping hole a31, and the valve core sleeve damping tube b29 is far away from the valve core damping hole b32. According to the linear relationship between distance and pressure, it can be known that the pressure in the valve core damping hole a31 will decrease, while the pressure in the valve core damping hole b32 will increase. As a result, the pressure in the sensitive chamber a15 can be made lower than the pressure in the sensitive chamber b21, thereby driving the main valve core tube 11 to move toward the sensitive chamber a15, and then connecting the oil inlet chamber 23 with the working chamber a22, and opening the oil outlet a3. On the contrary, when it is necessary to open the oil outlet b36, the servo motor 1 drives the pilot valve core sleeve 14 to rotate in the opposite direction, so that the valve core sleeve damping tube a28 is far away from the valve core damping hole a31, and the valve core sleeve damping tube b29 is close to the valve core damping hole b32, and the rest of the principles are the same. It should be noted that: when the servo motor 1 stops rotating, the pilot valve core 13 is reset to the same rotation 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 the pressure balance state, and the main valve core tube 11 will be reset to the middle position.

[0046] In the device, since the damping channel is uniform and the pressure in the oil return system is fixed, the pressure in the sensitive chamber a15 is linearly related to the distance between the valve core damping hole a31 and the valve core sleeve damping tube a28, and the pressure in the sensitive chamber b21 is linearly related to the distance between the valve core damping hole b32 and the valve core sleeve damping tube b29; the damping length and angle relationship is a linear relationship with the radius of the pilot valve core sleeve 14 as the proportional coefficient; the angle and the pulse of the servo motor 1 are linearly related. Therefore, the digital control of the servo motor 1 and the pressure at both ends of the main valve core tube 11 are linearly related. At the same time, since the displacement or opening of the main valve core tube 11 of the valve can form a linear relationship with the flow rate, when the inlet and outlet pressures of the valve are constant, the step servo motor 1 can directly obtain a digital flow signal through a digital signal, and this characteristic is not available in the nozzle flapper servo valve.

[0047] In addition, the existing nozzle flapper valve and 2D digital valve mainly obtain pressure signals by blocking one of the valve core damping holes or the valve core damping holes are of different sizes, and cooperate with the nozzle conversion of the nozzle flapper valve and the throttle hole conversion of the 2D digital valve to achieve the switching of the oil outlet. Therefore, the existing technology has high requirements on the viscosity and cleanliness of the oil, otherwise it is easy to get clogged and cause failure. The digital servo valve uses the distance adjustment between the valve core damping tube and the oil inlet hole 33 to achieve the pressure size adjustment of the corresponding valve core damping hole. It has relatively low requirements on the oil and strong anti-pollution ability.

[0048] In addition, the digital servo valve proposes a rotary disk mode coupling, that is, a rotary disk coupling mode is used between the pilot valve core sleeve 14 and the pilot valve core 13, instead of the mechanical connection of the thread feedback mode of the existing 2D digital valve. This mode will not cause the thread mode to get stuck at the extreme position and the problem of mechanical backlash.

[0049] In the digital servo valve, in order to realize the rotational drive of the pilot valve core sleeve 14 by the servo motor 1, the outer wall 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 through 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. The sealing ring 3 can prevent the oil from directly contacting the servo motor 1, and the rolling bearing 4 can ensure the smooth rotation of the pilot valve core sleeve 14.

[0050] At the same time, in the present 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, so 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 face 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 face 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 active 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 also provided with two annular grooves, one of which is connected to the oil return port a16 to form an oil return chamber a17, and the other annular groove is connected to the oil return port b19 to form an oil return chamber b20. The valve core sleeve damping tube a28 and the valve core sleeve damping tube b29 are both connected to the oil return port a16 and the oil return port b19 through an oil return channel 18 provided in the valve body 12. This design is to meet the situation that the oil outlet a35 and the oil outlet b36 of the digital servo valve are respectively connected to the oil inlet channel and the oil outlet channel of the same load. In this case, the working requirements of the forward / reverse circulation of the oil in the load can be met by the digital servo valve.

[0052] Specifically: When using the digital servo valve in this case, the oil outlet a35 and the oil outlet b36 of the digital servo valve need to be connected to the oil inlet channel and the oil outlet channel of the same load respectively, and the oil return port a16 and the oil return port b19 of the digital servo valve need to be connected to the inlet of the return oil tank respectively. When in use, when the oil outlet a35 is opened with the movement of the main valve core tube 11, the oil inlet chamber 23 is connected to the working chamber a22. At the same time, the oil return chamber a17 is not connected to the working chamber a22, but the oil return chamber b19 is connected to the working chamber b20. In this case, the pressure oil will be input into the load from the oil inlet channel / oil outlet channel of the load, and output from the oil outlet channel / oil inlet channel to the oil outlet b36. At this time, because the oil return chamber b19 is connected to the working chamber b20, the oil can be input back to the oil tank through the oil return port b19, thereby realizing the working requirement of oil circulation in the load. Similarly, when the oil outlet b36 is opened with the movement of the main valve core tube 11, the oil circulation in the load can also be realized, but the oil in the load flows in the reverse direction.

[0053] At the same time, a pressure plate 10 is sleeved on one end of the pilot valve core 13 away from the pilot valve core sleeve 14. 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 arranged between the pressure plate 10 and the sealing end cover 8 arranged near the pressure plate 10. 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. By twisting the locking nut 9, the pressure plate 10 can be locked, thereby preventing the sealing end cover 8 from loosening, thereby affecting the stability of the entire system.

[0054] In addition, since there is a length difference between the communication channel connecting the valve core damping hole a31 and the sensitive chamber a15 and the communication channel connecting the valve core damping hole b32 and the sensitive chamber b21, in the initial state, in order to balance the pressure difference in the sensitive chamber a15 and the sensitive chamber b21 caused by the length difference, a centering spring 7 sleeved on the pilot valve core 13 is provided between the sealing end cover 8 and the end face of the main valve core tube 11, and the two ends of the centering spring 7 are in close contact with the sealing end cover 8 and the end face of the main valve core tube 11 respectively.

[0055] It should be noted that:

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

[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) which are 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) which are arranged in sequence along the axial direction thereof, characterized in that: A pilot valve core (13) is coaxially fixedly disposed in the valve body (12) and has an outer wall that is gap-matched 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 cooperation 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), and the main valve core tube (11) is movable along its axial direction and is in sliding sealing cooperation 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 chamber a (15) and a sensitive chamber 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 that is connected with the oil inlet (37) to form an oil inlet chamber (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 rotational 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 arranged on opposite sides of the oil inlet hole (33); the oil inlet hole (33) ) is connected to the oil inlet chamber (23) through a high-pressure passage (30) provided in the pilot valve core (13); the valve core damping hole a (31) is connected to the sensitive chamber a (15) through a communication passage provided in the pilot valve core (13); the valve core damping hole b (32) is connected to the sensitive chamber b (21) through a communication passage provided in the pilot valve core (13); and the valve core damping hole a (31) and the valve core damping hole b (32) are connected to the sensitive chamber b (21) through a communication passage provided in the pilot valve core (13); and the damping groove (27) on the opposite sides of 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 connected to both the oil return port a (16) and the oil return port b (19).

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 limit 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); 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); and an end of the limit pin (25) away from the pilot valve core (13) is movably inserted in the limit hole (26).

4. The digital servo valve according to claim 1, characterized in that: The outer wall of the main valve core tube (11) is also 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); 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 arranged between the pressure plate (10) and the sealing end cover (8) arranged close to the pressure plate (10); 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 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) is communicated with the high-pressure channel (30) via a main valve core hole (34) arranged on the side wall of the main valve core tube (11).

Images