An electro-hydraulic servo screw-driven large-flow multi-way valve and its working method

Abstract

The present invention discloses an electro-hydraulic servo spiral drive type large flow multi-way valve and its working method, belonging to the technical field of electro-hydraulic proportional multi-way valves. It includes a pilot unit, a main stage and a reset unit; the pilot unit includes a control motor, a servo sleeve, and a pilot shaft, a spiral groove is provided on the pilot shaft, and a high / low pressure distribution port is provided on the servo sleeve. The pilot unit is fixed on the main stage, the servo sleeve is concentric with the main valve core and fixedly connected, the motor shaft drives the pilot shaft to rotate, and the main valve core is driven to move by the hydraulic servo spiral, and the motor rotation angle corresponds to the displacement of the main valve core. The multi-way valve of the present invention deeply integrates the advantages of high-precision motor control and high-thrust hydraulic drive, and has the characteristics of low pilot drive power, fast response, high precision, low cost, etc., which can meet the needs of high-precision control and intelligence of engineering machinery.

Description

Technical Field

[0001] The present invention belongs to the technical field of electro-hydraulic proportional multi-way valves, and in particular relates to an electro-hydraulic servo spiral-driven large-flow multi-way valve and a working method thereof. Background Art

[0002] The multi-way valve is one of the core components of engineering machinery. Its function is to distribute the pressure of the oil source to multiple branches and adjust the flow of each branch. Its performance determines the controllability and energy saving of engineering machinery. There are two control methods for large-flow multi-way valves: (1) using a proportional pressure reducing valve as a pilot unit to drive the main valve core, and controlling the opening of the main valve by adjusting the pressure of the proportional pressure reducing valve. This method belongs to open-loop control, which is low in cost and widely used, but the control accuracy is not high and the response is slow, which makes it difficult to meet the high-precision control requirements of engineering machinery. (2) using a pilot structure of a proportional directional valve + displacement sensor + controller to perform closed-loop control on the main valve core of the multi-way valve. This method has high control accuracy and fast response, but it is complex in structure, expensive, poor in environmental adaptability, and low in reliability, so it is rarely used in practice.

[0003] It can be seen that the current structural solution of large-flow multi-way valves is difficult to resolve the contradiction between performance (accuracy, response, reliability) and cost, and is difficult to meet the needs of engineering machinery for development towards high precision and intelligence. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides an electro-hydraulic servo spiral-driven large-flow multi-way valve and its working method, which adopts motor control and hydraulic drive to control the main valve core, and can take into account the performance and cost of the large-flow multi-way valve.

[0005] To achieve the above technical objectives, the present invention discloses an electro-hydraulic servo spiral-driven large-flow multi-way valve, including multiple sections, each section including a pilot unit and a reset unit arranged on a main stage, the main stage including a main valve body, a pressure oil passage P, a drain oil passage T, and working oil passages A and B arranged therein; a main valve core is arranged in the main valve body; a pilot unit is arranged on the left side of the main valve body and fixedly connected by bolts, the pilot unit including a pilot valve body, a servo sleeve is arranged in the pilot valve body, the servo sleeve is connected to the left side of the main valve core and drives the main valve core to move, and the servo sleeve controls the flow direction and flow rate of each oil channel by driving the main valve core to move; the reset unit is arranged on the right side of the main valve body and fixedly connected by bolts to achieve the reset of the main valve core;

[0006] The pilot unit includes sequentially connected components: a control motor, a coupling, a connecting end cover and a pilot valve body. The coupling is arranged on the inner side of the connecting end cover. The connecting end cover and the pilot valve body are fixed by connecting bolts. The components are sealed by static seals. A servo sleeve with a piston structure is provided inside the pilot valve body. The servo sleeve includes a piston plug part and a piston rod part. A sealing cover is provided between the outer side of the piston rod part of the servo sleeve and the inner side of the pilot valve body. An inner hole is provided axially on the inner side of the servo sleeve. The motor shaft of the control motor is connected to the pilot shaft through a coupling. The coupling is arranged inside the connecting end cover, the pilot shaft passes through the connecting end cover and is concentrically matched with the inner hole of the servo sleeve, the servo sleeve passes through the sealing cover and is fixedly connected to the end of the main valve core through connecting screws; the servo sleeve forms a piston structure in the pilot valve body, the enclosed space between the left side of the servo sleeve and the right side of the connecting end cover constitutes the sensitive chamber b, and the enclosed space between the right side of the servo sleeve and the left side of the sealing cover constitutes the constant pressure chamber e, the constant pressure chamber e is connected to the pilot oil circuit of the multi-way valve, and the pressures of the sensitive chamber b and the constant pressure chamber e act on both sides of the piston plug head of the servo sleeve respectively;

[0007] Two spiral grooves c are symmetrical along the center line on the outer cylindrical surface of the pilot shaft, and a high-pressure distribution hole d and a low-pressure distribution hole k are provided on the inner wall of the piston plug of the servo sleeve. The two spiral grooves c are connected to the sensitive chamber b; when the control motor drives the pilot shaft to rotate, the two spiral grooves c are connected with the high-pressure distribution hole d or the low-pressure distribution hole k to form a throttle, so that the sensitive chamber b is connected with the high-pressure distribution hole d or the low-pressure distribution hole k. The pressure in the sensitive chamber b changes, which drives the servo sleeve to move while the throttle gradually decreases, thereby controlling the displacement of the main valve core, thereby forming an electro-hydraulic servo spiral drive, and ultimately controlling the rotation angle of the motor to be proportional to the displacement of the main valve core.

[0008] Furthermore, a low-pressure chamber a is provided in the connecting end cover with a coupling, a low-pressure chamber h is formed in the space between the sealing cover and the main valve body, and a low-pressure chamber f is formed by the right end face of the pilot shaft and the inner hole of the servo sleeve; a high-pressure flow channel j and a low-pressure flow channel i are also provided in the servo sleeve, wherein one end of the high-pressure flow channel j is connected to the constant pressure chamber e and the other end is connected to the high-pressure distribution hole d, while one end of the low-pressure flow channel i is connected to the low-pressure chamber f and the other end is connected to the low-pressure distribution hole k; a through hole L is axially provided inside the pilot shaft, and the through hole L connects the low-pressure chamber a and the low-pressure chamber f, and a channel g is provided on the side wall of the servo sleeve near the main valve core, and the low-pressure chamber f is connected to the low-pressure chamber h through the channel g, and the low-pressure chamber h is connected to the oil unloading path of the multi-way valve, so that all low-pressure chambers in the pilot unit are kept at low pressure.

[0009] Furthermore, two limiting threaded holes are symmetrically provided at the right end of the connecting end cover along the axial direction, and two limiting circular holes are symmetrically provided at the left end of the servo sleeve along the axial direction. The two limiting threaded holes of the connecting end cover and the two limiting circular holes of the servo sleeve are connected by two limiting pins. The two limiting pins can slide in the two limiting circular holes of the servo sleeve to ensure that the servo sleeve can only move axially along the inner hole of the pilot valve body without generating rotational motion.

[0010] Furthermore, the control motor is a low-power motor that can accurately control the rotation angle, including: a servo motor and a stepper motor.

[0011] Furthermore, the reset unit includes an end cover with a hollow structure, the end of the end cover is sealed by a screw plug, and a left limit cover, a right limit cover and a reset rod are sequentially arranged in the end cover, the left end of the reset rod passes through the left limit cover and is connected to the main valve core by a threaded connection, a reset spring is provided on the outside of the reset rod between the limit cover and the right limit cover, an inner hole is provided in the center of the right limit cover, the reset rod can slide in the inner hole of the right limit cover, and a cylindrical guide rod is provided at the outer cylindrical surface of the reset rod to guide the compression of the reset spring; when there is no external control force, the reset rod drives the main valve core to return to the middle position under the action of the spring force of the reset spring.

[0012] Furthermore, a rotating dynamic seal is set between the pilot shaft and the inner hole of the connecting end cover, a sliding seal is set between the outer cylindrical surface of the right end of the servo sleeve and the inner hole of the sealing cover, and a sliding seal is set between the outer cylindrical surface of the left end of the servo sleeve and the inner cylindrical surface of the pilot valve body. The outer cylindrical surface of the left end of the servo sleeve is provided with multiple annular pressure equalizing grooves to prevent the servo sleeve from getting stuck.

[0013] A working method of an electro-hydraulic servo screw-driven large-flow multi-way valve, wherein the working method of any one link in the multi-way valve is as follows:

[0014] When the control motor is reset, the spiral groove c is not connected to the high-pressure distribution hole d or the low-pressure distribution hole k;

[0015] When the control motor rotates counterclockwise, the spiral groove c on the pilot shaft cooperates with the high-pressure distribution hole d to form an opening, and the high-pressure oil flows from the constant pressure chamber e through the high-pressure flow channel j, the high-pressure distribution hole d, and the spiral groove c into the sensitive chamber b. At this time, the sensitive chamber b is at high pressure, and the piston plug of the servo sleeve moves right under the action of the pressure difference between the left and right sides, thereby driving the main valve core to move right synchronously; while the servo sleeve moves right, the cooperation opening between the high-pressure distribution hole d and the spiral groove c is gradually closed; when the control motor stops rotating, the servo sleeve stops moving, and the main valve core forms an opening: the pressure channel P is connected to the working channel B, and the oil drain channel T is connected to the working oil channel A;

[0016] When the control motor rotates clockwise, the spiral groove c on the pilot shaft cooperates with the low-pressure distribution hole k to form an opening. The oil in the sensitive chamber b flows through the low-pressure distribution hole k and the low-pressure flow channel i to the low-pressure chamber f, and then flows through the channel g to the low-pressure chamber h. At this time, the sensitive chamber b is at low pressure, and the high pressure of the constant-pressure chamber e acts on the right step surface of the servo sleeve piston plug, pushing the servo sleeve to move left. As the servo sleeve moves left, the cooperation opening between the low-pressure distribution hole k and the spiral groove c is gradually closed. When the control motor stops rotating, the servo sleeve stops moving. At this time, the main valve core forms an opening: the pressure channel P is connected to the working channel A, and the oil drain channel T is connected to the working oil channel B.

[0017] Through the electro-hydraulic servo screw drive, the motor rotation angle is controlled to correspond one to one with the displacement of the main valve core, thereby achieving precise control of the large-flow multi-way valve.

[0018] Beneficial effects:

[0019] The electro-hydraulic servo-screw-driven high-flow multi-way valve proposed in this invention utilizes an electro-hydraulic servo-screw drive, fully integrating the advantages of high-precision motor control and high-thrust hydraulic drive. The motor's rotation angle corresponds exactly to the main valve core's displacement, enabling precise control of the main valve core's displacement without the need for a displacement sensor or complex control system. Compared to traditional high-flow multi-way valves, the proposed multi-way valve offers significant advantages, including low pilot drive power, high control accuracy, fast response, and low cost. It is particularly suitable for high-pressure, high-flow applications and meets the urgent need for high-precision control and intelligent control in construction machinery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a three-dimensional structural schematic diagram of the electro-hydraulic servo spiral drive large flow multi-way valve of the present invention.

[0021] Figure 2 It is a schematic diagram of the internal structure of the electro-hydraulic servo spiral drive type large flow multi-way valve of the present invention.

[0022] Figure 3 It is a three-dimensional assembly drawing of the pilot unit in the present invention.

[0023] Figure 4 It is an exploded view of the pilot unit in the present invention.

[0024] Figure 5 It is a schematic diagram of the principle of the electro-hydraulic servo screw drive in the present invention.

[0025] Figure 6 It is a structural diagram of the servo sleeve in the present invention.

[0026] Figure 7 It is a structural diagram of the reset unit in the present invention.

[0027] Figure 8This is a step response curve of the main valve core during operation of the electro-hydraulic servo screw-driven large-flow multi-way valve in an embodiment of the present invention.

[0028] Figure 9 It is the slope tracking curve of the main valve core during operation of the electro-hydraulic servo spiral-driven large-flow multi-way valve in the embodiment of the present invention. DETAILED DESCRIPTION

[0029] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0030] like Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, the present invention discloses an electro-hydraulic servo spiral-driven large-flow multi-way valve, including multiple sections, each section including three parts: a pilot unit, a main stage, and a reset unit; the main stage includes a main valve body 11, inside which a pressure oil channel P, an oil drain channel T, and working oil channels A and B are arranged, and a main valve core 10 is arranged in the main valve body 11; the pilot unit is arranged on the left side of the main valve body 11 and is fixedly connected by bolts, and a servo sleeve 8 is provided in the pilot unit, which drives the main valve core 10 to move to control the flow direction and flow rate of each oil channel; the reset unit is arranged on the right side of the main valve body 11 and is fixedly connected by screws to achieve the reset of the main valve core 10.

[0031] The pilot unit includes a control motor 1, a connecting end cover 4 and a pilot valve body 9 which are connected in sequence by connecting bolts 5, and each component is sealed by a static seal 2; a servo sleeve 8 and a sealing cover 20 are provided inside the pilot valve body 9; the motor shaft 23 of the control motor 1 is connected to the pilot shaft 7 which controls the opening and closing degree of the hydraulic oil channel by the rotation angle through a coupling 3, and the coupling 3 is arranged inside the connecting end cover 4; the pilot shaft 7 passes through the connecting end cover 4 and is concentrically matched with the inner hole of the servo sleeve 8, and the servo sleeve 8 passes through the sealing cover 20 and is fixedly connected to the end of the main valve core 10 by a connecting screw 19; the enclosed space between the left side of the servo sleeve 8 and the right side of the connecting end cover 4 constitutes a sensitive chamber b, and the enclosed space between the right side of the servo sleeve 8 and the left side of the sealing cover 20 constitutes a constant pressure chamber e, which is connected to the pilot oil circuit of the multi-way valve, and the pressures of the sensitive chamber b and the constant pressure chamber e act on both sides of the servo sleeve 8 respectively.

[0032] like Figure 5 and Figure 6As shown, a spiral groove c symmetrically along the center line is provided on the outer cylindrical surface of the pilot shaft 7, and a high-pressure distribution hole d and a low-pressure distribution hole k are provided on the inner wall of the servo sleeve 8. The spiral groove c is connected to the sensitive cavity b; when the control motor 1 drives the pilot shaft 7 to rotate, the spiral groove c will be connected to the high-pressure distribution hole d or the low-pressure distribution hole k to form a throttle port, and the pressure in the sensitive cavity changes, pushing the servo sleeve 8 to move while the throttle port gradually decreases, thereby controlling the displacement of the main valve core 10, thereby forming an electro-hydraulic servo spiral drive, and ultimately controlling the rotation angle of the motor 1 to be proportional to the displacement of the main valve core 10. The pilot unit contains multiple low-pressure chambers, the connecting end cover 4 contains the low-pressure chamber a, the space between the sealing cover 20 and the main valve body 11 constitutes the low-pressure chamber h, and the right end face of the pilot shaft 7 and the inner hole of the servo sleeve 8 also form a low-pressure chamber f; the servo sleeve 8 also has a high-pressure flow channel j and a low-pressure flow channel i, wherein one end of the high-pressure flow channel j is connected to the constant pressure chamber e, and the other end is connected to the high-pressure distribution hole d, while one end of the low-pressure flow channel i is connected to the low-pressure chamber f, and the other end is connected to the low-pressure distribution hole k; a through hole L is opened inside the pilot shaft 7, and the through hole L connects the low-pressure chamber a and the low-pressure chamber f, and the low-pressure chamber f is connected to the low-pressure chamber h through the channel g, and the low-pressure chamber h is connected to the oil unloading path of the multi-way valve, so that all the low-pressure chambers in the pilot unit are kept at low pressure.

[0033] like Figure 3 and 4 As shown, two limiting threaded holes are symmetrically opened at the right end of the connecting end cover 4 along the axial direction, and two limiting circular holes are symmetrically opened at the left end of the servo sleeve 8 along the axial direction. The left end of the limiting pin 6 is fixed to the connecting end cover 4 by a threaded connection, and the right end of the limiting pin 6 is inserted into the limiting circular hole of the servo sleeve 8 to ensure that the servo sleeve 8 can only move axially along the inner hole of the pilot valve body 9 without generating rotational motion.

[0034] The control motor 1 is a low-power motor that can accurately control the rotation angle, including but not limited to a servo motor and a stepper motor.

[0035] like Figure 7 As shown, the reset unit includes an end cover 17 with a hollow structure, the end of the end cover 17 is sealed by a screw plug 16, and a left limit cover 12, a right limit cover 15 and a reset rod 13 are provided in the end cover 17. A compressed reset spring 18 is provided between the two end covers. The left end of the reset rod 13 passes through the left limit cover 12 and is connected to the main valve core 10 by a threaded connection. The reset rod 13 can slide in the inner hole of the right limit cover 15. A cylindrical guide rod 14 is provided on the outer cylindrical surface of the reset rod 13 to guide the compression of the reset spring 18; when there is no external control force, the reset rod 13 drives the main valve core 10 to return to the middle position under the action of the spring force of the reset spring 18.

[0036] like Figure 3As shown, multiple sliding seals are provided in the pilot unit, wherein a rotating dynamic seal 22 is provided between the pilot shaft 7 and the inner hole of the connecting end cover 4, a sliding seal 24 is provided between the outer cylindrical surface of the right end of the servo sleeve 8 and the inner hole of the sealing cover 20, a sliding seal 21 is provided between the outer cylindrical surface of the left end of the servo sleeve 8 and the inner cylindrical surface of the pilot valve body 9, and the outer cylindrical surface of the left end of the servo sleeve 8 is provided with multiple annular pressure-equalizing grooves to prevent the servo sleeve 8 from moving and getting stuck.

[0037] The working method of any one of the electro-hydraulic servo screw-driven large flow multi-way valves is as follows:

[0038] When the control motor 1 rotates counterclockwise, the spiral groove c cooperates with the high-pressure distribution hole d to form an opening, and the high-pressure oil flows from the constant pressure chamber e through the high-pressure flow channel j, the high-pressure distribution hole d, and the spiral groove c in sequence into the sensitive chamber b. At this time, the sensitive chamber b is at high pressure, and the servo sleeve 8 moves right under the action of the pressure difference on the left and right sides, thereby driving the main valve core 10 to move right synchronously; while the servo sleeve 8 moves right, the cooperation opening of the high-pressure distribution hole d and the spiral groove c is gradually closed; when the control motor 1 stops rotating, the servo sleeve 8 moves to a certain position, at which time the main valve core maintains a certain opening, so that the pressure channel P is connected to the working channel B, and the oil drain channel T is connected to the working oil channel A;

[0039] When the control motor 1 rotates clockwise, the spiral groove c cooperates with the low-pressure distribution hole k to form an opening, and the oil in the sensitive chamber b flows through the low-pressure distribution hole k and the low-pressure flow channel i to the low-pressure chamber f in sequence, and then flows through the channel g to the low-pressure chamber h. At this time, the sensitive chamber b is at low pressure, and the high pressure of the constant-pressure chamber e acts on the step surface on the right side of the servo sleeve 8, pushing the servo sleeve 8 to move left. As the servo sleeve 8 moves left, the cooperation opening of the low-pressure distribution hole k and the spiral groove c is gradually closed; when the control motor 1 stops rotating, the servo sleeve 8 moves to a certain position. At this time, the main valve core maintains a certain opening, so that the pressure channel P is connected to the working channel A, and the oil drain channel T is connected to the working oil channel B;

[0040] Through the electro-hydraulic servo screw drive, the rotation angle of the control motor 1 corresponds to the displacement of the main valve core 10, thereby achieving precise control of the large-flow multi-way valve.

[0041] Example: An electro-hydraulic servo screw-driven large flow multi-way valve, the shape of which is as follows Figure 1 As shown in the figure, a step response experiment was carried out. The test results are shown in the figure. Figure 8 As shown, the step amplitude is 4mm, the step response time is less than 100ms, and the steady-state control accuracy is less than ±0.02mm.

[0042] The slope tracking experiment was carried out using the electro-hydraulic servo screw-driven large flow multi-way valve. Figure 9As shown in the figure, the main valve core displacement changes continuously between -6mm and 6mm according to a certain slope, and the dynamic following error is less than ±0.6mm.

[0043] The above experiments fully demonstrate that the structural principle of the new large-flow multi-way valve proposed in the present invention is feasible. It can easily realize the position control of the main valve core of the multi-way valve through electro-hydraulic servo screw drive, and has the outstanding advantages of high response and high precision. It is simple to control and has low cost, which can meet the high-precision and intelligent development needs of engineering machinery.

[0044] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An electro-hydraulic servo screw-driven large-flow multi-way valve, including multiple connections, characterized by: Each link includes a pilot unit and a reset unit arranged on the main stage, the main stage includes a main valve body (11), a pressure oil channel P, a drain oil channel T, a working oil channel A and a working oil channel B are arranged inside the main valve body (11); a main valve core (10) is arranged inside the main valve body (11); the pilot unit is arranged on the left side of the main valve body (11) and is fixedly connected by bolts, the pilot unit includes a pilot valve body (9), a servo sleeve (8) is arranged inside the pilot valve body (9), the servo sleeve (8) is connected to the left side of the driving main valve core (10) and drives the main valve core (10) to move, and the servo sleeve (8) controls the flow direction and flow size of each oil by driving the main valve core (10) to move; the reset unit is arranged on the right side of the main valve body (11) and is fixedly connected by bolts to achieve the reset of the main valve core (10); The pilot unit comprises sequentially connected components: a control motor (1), a coupling (3), a connecting end cover (4) and a pilot valve body (9), wherein the coupling (3) is arranged on the inner side of the connecting end cover (4), the connecting end cover (4) and the pilot valve body (9) are fixed by connecting bolts (5), and each component is sealed by a static seal (2); a servo sleeve (8) with a piston structure is provided inside the pilot valve body (9), the servo sleeve (8) comprises a piston plug part and a piston rod part, a sealing cover (20) is provided between the outer side of the piston rod part of the servo sleeve (8) and the inner side of the pilot valve body (9), and an inner hole is provided axially on the inner side of the servo sleeve (8); the motor shaft (23) of the control motor (1) is connected to the control motor (1) through the coupling (3) A pilot shaft (7) is provided, and a coupling (3) is arranged inside a connecting end cover (4). The pilot shaft (7) passes through the connecting end cover (4) and is concentrically matched with the inner hole of the servo sleeve (8). The servo sleeve (8) passes through the sealing cover (20) and is fixedly connected to the end of the main valve core (10) by a connecting screw (19); the servo sleeve (8) forms a piston structure in the pilot valve body (9), and the closed space between the left side of the servo sleeve (8) and the right side of the connecting end cover (4) constitutes a sensitive chamber b, and the closed space between the right side of the servo sleeve (8) and the left side of the sealing cover (20) constitutes a constant pressure chamber e. The constant pressure chamber e is connected to the pilot oil circuit of the multi-way valve, and the pressures of the sensitive chamber b and the constant pressure chamber e act on both sides of the piston plug part of the servo sleeve (8). Two spiral grooves c are provided on the outer cylindrical surface of the pilot shaft (7) and are symmetrical along the center line. A high-pressure distribution hole d and a low-pressure distribution hole k are provided on the inner wall of the piston plug of the servo sleeve (8). The two spiral grooves c are connected to the sensitive cavity b. When the control motor (1) drives the pilot shaft (7) to rotate, the two spiral grooves c are connected to the high-pressure distribution hole d or the low-pressure distribution hole k and form a throttle port, thereby connecting the sensitive cavity b with the high-pressure distribution hole d or the low-pressure distribution hole k. The pressure of the sensitive cavity b changes, pushing the servo sleeve (8) to move while the throttle port gradually decreases, thereby controlling the displacement of the main valve core (10), thereby forming an electro-hydraulic servo spiral drive, and finally controlling the rotation angle of the motor (1) to be proportional to the displacement of the main valve core (10).

2. The electro-hydraulic servo screw-driven large flow multi-way valve according to claim 1, characterized in that: The connection end cover (4) provided with the coupling (3) has a low-pressure chamber a, the space between the sealing cover (20) and the main valve body (11) forms a low-pressure chamber h, and the right end surface of the pilot shaft (7) and the inner hole of the servo sleeve (8) form a low-pressure chamber f; a high-pressure flow channel j and a low-pressure flow channel i are also provided in the servo sleeve (8), wherein one end of the high-pressure flow channel j is connected to the constant-pressure chamber e and the other end is connected to the high-pressure distribution hole d, while one end of the low-pressure flow channel i is connected to the low-pressure chamber f and the other end is connected to the low-pressure distribution hole k; a through hole L is provided in the axial direction inside the pilot shaft (7), and the through hole L connects the low-pressure chamber a and the low-pressure chamber f; a channel g is provided on the side wall of the servo sleeve (8) close to the main valve core (10), and the low-pressure chamber f is connected to the low-pressure chamber h through the channel g, and the low-pressure chamber h is connected to the oil unloading path of the multi-way valve, so that all the low-pressure chambers in the pilot unit are kept at low pressure.

3. The electro-hydraulic servo screw-driven large flow multi-way valve according to claim 1, characterized in that: The right end of the connecting end cover (4) is symmetrically provided with two limiting threaded holes along the axial direction, and the left end of the servo sleeve (8) is symmetrically provided with two limiting circular holes along the axial direction. The two limiting threaded holes of the connecting end cover (4) and the two limiting circular holes of the servo sleeve (8) are connected by two limiting pins (6). The two limiting pins (6) can slide in the two limiting circular holes of the servo sleeve (8) to ensure that the servo sleeve (8) can only move axially along the inner hole of the pilot valve body (9) without generating rotational motion.

4. The electro-hydraulic servo screw-driven large flow multi-way valve according to claim 1, characterized in that: The control motor (1) is a low-power motor capable of accurately controlling the rotation angle, including a servo motor and a stepper motor.

5. The electro-hydraulic servo screw-driven large flow multi-way valve according to claim 1, characterized in that: The reset unit includes an end cover (17) with a hollow structure. The end of the end cover (17) is sealed by a screw plug (16). A left limit cover (12), a right limit cover (15) and a reset rod (13) are sequentially arranged in the end cover (17). The left end of the reset rod (13) passes through the left limit cover (12) and is connected to the main valve core (10) by a thread. A reset spring (18) is sleeved on the outer side of the reset rod (13) between the limit cover (12) and the right limit cover (15). An inner hole is provided at the center of the right limit cover (15). The reset rod (13) can slide in the inner hole of the right limit cover (15). A cylindrical guide rod (14) is provided at the outer cylindrical surface of the reset rod (13) to guide the compression of the reset spring (18); when there is no external control force, the reset rod (13) drives the main valve core (10) to return to the middle position under the action of the spring force of the reset spring (18).

6. The electro-hydraulic servo screw-driven large flow multi-way valve according to claim 1, characterized in that: A rotary dynamic seal (22) is provided between the pilot shaft (7) and the inner hole of the connecting end cover (4), a sliding seal (24) is provided between the outer cylindrical surface of the right end of the servo sleeve (8) and the inner hole of the sealing cover (20), and a sliding seal (21) is provided between the outer cylindrical surface of the left end of the servo sleeve (8) and the inner cylindrical surface of the pilot valve body (9). The outer cylindrical surface of the left end of the servo sleeve (8) is provided with a plurality of annular pressure-equalizing grooves to prevent the servo sleeve (8) from moving and getting stuck.

7. A method for operating the electro-hydraulic servo screw-driven large flow multi-way valve according to any one of claims 1 to 6, characterized in that The working method of any link is as follows: When the control motor (1) is reset, the spiral groove c is not connected to the high-pressure distribution hole d or the low-pressure distribution hole k; When the control motor (1) rotates counterclockwise, the spiral groove c on the pilot shaft (7) cooperates with the high-pressure distribution hole d to form an opening, and the high-pressure oil passes through the high-pressure flow channel j, the high-pressure distribution hole d, and the spiral groove c from the constant pressure chamber e into the sensitive chamber b. At this time, the sensitive chamber b is at high pressure, and the piston plug part of the servo sleeve (8) moves right under the action of the pressure difference between the left and right sides, thereby driving the main valve core (10) to move right synchronously; while the servo sleeve (8) moves right, the cooperation opening of the high-pressure distribution hole d and the spiral groove c is gradually closed; when the control motor (1) stops rotating, the servo sleeve (8) stops moving, and the main valve core (10) forms an opening: the pressure channel P is connected to the working channel B, and the oil drain channel T is connected to the working oil channel A; When the control motor (1) rotates clockwise, the spiral groove c on the pilot shaft (7) cooperates with the low-pressure distribution hole k to form an opening, and the oil in the sensitive chamber b flows through the low-pressure distribution hole k and the low-pressure flow channel i to the low-pressure chamber f, and then flows through the channel g to the low-pressure chamber h. At this time, the sensitive chamber b is low-pressure, and the high-pressure of the constant-pressure chamber e acts on the right step surface of the piston plug of the servo sleeve (8), pushing the servo sleeve (8) to move left. At the same time as the servo sleeve (8) moves left, the cooperation opening of the low-pressure distribution hole k and the spiral groove c is gradually closed; when the control motor (1) stops rotating, the servo sleeve (8) stops moving, and the main valve core (10) forms an opening: the pressure channel P is connected to the working channel A, and the oil drain channel T is connected to the working oil channel B; By means of electro-hydraulic servo screw drive, the rotation angle of the control motor (1) corresponds to the displacement of the main valve core (10) in a one-to-one manner, thereby achieving precise control of a large flow multi-way valve.

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