Double spool reversing valve

Abstract

This invention relates to a dual-spool directional control valve, comprising a valve body and valve spools. The valve body has a valve spool cavity, a pressure port, a return port, a first port, and a second port. There are two valve spools, a first valve spool and a second valve spool, coaxially arranged. The first valve spool is driven axially by a first driving structure, and the second valve spool is driven axially by a second driving structure. The inner ends of the first and second valve spools are interlocked, and the first and second valve spools can move axially relative to each other. The axial movement of the first valve spool can connect the first port to the pressure port or the return port, or block the first port from both the pressure port and the return port. The axial movement of the second valve spool can connect the second port to the pressure port or the return port, or block the second port from both the pressure port and the return port. This valve has the advantages of compact structure, multi-purpose functionality, and controllable opening degree.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic transmission and control, and particularly relates to a dual-core directional valve. Background Technology

[0002] Directional control valves are widely used in the hydraulic and pneumatic transmission industry. For many years, existing four-way or multi-way directional control valves have used electromagnetic directional control valves, which use the thrust generated by energizing an electromagnetic coil to drive the valve core of the directional control valve to move, thereby realizing hydraulic or pneumatic directional control and changing the running direction of the hydraulic or pneumatic actuator.

[0003] Chinese utility model patent "A Sealing Structure for an Electro-hydraulic Directional Control Valve" with patent number ZL202423179955.6 (publication number CN223524097U) discloses such a conventional directional control valve structure, including an electro-hydraulic directional control valve body, a hydraulically controlled directional control valve, and a hydraulic cylinder. Coils are provided at both ends of the inner side of the electro-hydraulic directional control valve body. A hydraulically controlled directional control valve is provided on the bottom surface of the electro-hydraulic directional control valve body. Nuts are provided on both ends of the hydraulically controlled directional control valve. An L-cavity and an R-cavity are respectively provided at both ends of the inner side of the hydraulically controlled directional control valve. A return spring and a sealing ring are respectively provided inside the L-cavity and R-cavity. An interface assembly is provided on the bottom surface of the hydraulically controlled directional control valve. A hydraulic cylinder is provided at the bottom of the hydraulically controlled directional control valve.

[0004] Existing solenoid directional valves have the following drawbacks: Ordinary solenoid directional valves have a single function, only usable as one of several types of valves such as two-position two-way valves, two-position three-way valves, two-position four-way valves, or three-position four-way valves. Furthermore, they cannot control the opening degree, limiting their application range. If a directional valve is required to have four or five operating positions, other valves must be added as auxiliary valves to achieve this. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a dual-core directional valve with a compact structure, which can realize multiple uses of a single valve and control the opening degree, in view of the above-mentioned existing technology. The directional valve also has the advantage of good dynamic response characteristics.

[0006] The first technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a dual-valve-core reversing valve, comprising a valve body and a valve core, wherein the valve body is provided with a valve core cavity and a pressure oil port, a return oil port, a first oil port, and a second oil port communicating with the valve core cavity; the valve core is disposed in the valve core cavity and can move axially; there are two valve cores, namely a first valve core and a second valve core arranged coaxially; the first valve core is driven by a first driving structure and can move axially, and the second valve core is driven by a second driving structure and can move axially; the inner ends of the first valve core and the second valve core are inserted into each other, and the first valve core and the second valve core can move axially relative to each other; the axial movement of the first valve core can enable the first oil port to communicate with the pressure oil port or the return oil port, or enable the first oil port to block both the pressure oil port and the return oil port; the axial movement of the second valve core can enable the second oil port to communicate with the pressure oil port or the return oil port, or enable the second oil port to block both the pressure oil port and the return oil port; the first driving structure includes a first control cavity located on the left side of the valve core cavity, and the outer end of the first valve core has The first valve core has a convex first annular shoulder, and its outer end extends into the first control chamber, dividing the first control chamber into a first external pressure chamber and a first internal pressure chamber. Oil inlet and outlet through the first external pressure chamber and the first internal pressure chamber drive the axial movement of the first valve core. The area of ​​the pressure oil in the first external pressure chamber acting on the first valve core is greater than the sum of the area of ​​the pressure oil in the first internal pressure chamber acting on the first valve core and the area acting on the first valve core after entering the valve core cavity through the pressure oil port. The second drive structure includes a second control chamber located on the right side of the valve core cavity. The second valve core has a convex second annular shoulder at its outer end, and its outer end extends into the second control chamber, dividing the second control chamber into a second external pressure chamber and a second internal pressure chamber. Oil inlet and outlet through the second external pressure chamber and the second internal pressure chamber drive the axial movement of the second valve core. The area of ​​the pressure oil in the second external pressure chamber acting on the second valve core is greater than the sum of the area of ​​the pressure oil in the second pressure chamber acting on the second valve core and the area acting on the second valve core after entering the valve core cavity through the pressure oil port.

[0007] To ensure that the first and second valve cores can slide axially (left and right) coaxially, the inner end of the first valve core is provided with a concave guide cavity, and the inner end of the second valve core is provided with a guide post for inserting into the guide cavity. A sealing structure is provided between the outer periphery of the guide post and the inner wall of the guide cavity. Since it is impossible to achieve a complete seal in the valve assembly, there will always be oil leakage. If hydraulic oil leaks into the guide cavity, it will affect the axial sliding of the first and second valve cores. To solve this problem, a second pressure relief channel is opened in the second valve core to connect the guide cavity and the return port. Since there may be back pressure at the return port, if the oil flow rate is high or reaches a peak value of more than ten kilograms, in order to prevent the pressurized oil in the return port from flowing into the guide cavity through the second pressure relief channel, a second check valve is provided in the second pressure relief channel. When the pressure in the guide cavity is greater than the back pressure at the return port, the second check valve opens to release the oil pressure in the guide cavity through the second pressure relief channel. Only when the back pressure at the return port is lower than 2 or 3 kilograms can the second check valve be opened to release oil.

[0008] To ensure a reasonable layout of the oil ports, the pressure oil port is located in the middle, the first oil port and the second oil port are located on the left and right sides of the pressure oil port and are adjacent to each other, and there are two return oil ports located on the outermost sides respectively. A connecting channel connecting the two return oil ports is provided above the valve core cavity.

[0009] In a further improvement, a first transition shaft is fixed inside the first external pressure chamber. The first transition shaft and valve body are provided with a first inlet channel and a first return channel. A first rotating shaft capable of rotating around its own axis passes through the first transition shaft. The rotation of the first rotating shaft is controlled by a first motor. A first inclined groove communicating with the first external pressure chamber is provided on the outer peripheral wall of the first rotating shaft. The rotation of the first rotating shaft can either connect the first inclined groove with one of the first inlet channel and the first return channel, or it can block the first inclined groove from both the first inlet channel and the first return channel. The first internal pressure chamber and the first inlet channel... The second external pressure chamber is connected; a second transition conversion shaft is fixed inside the second external pressure chamber. The second transition conversion shaft and the valve body are provided with a second inlet channel and a second return channel. A second rotating shaft that can rotate around its own axis is inserted inside the second transition conversion shaft. The second rotating shaft is controlled to rotate by a second motor. A second inclined groove that communicates with the second external pressure chamber is provided on the outer peripheral wall of the second rotating shaft. The rotation of the second rotating shaft can make the second inclined groove connect with one of the second inlet channel and the second return channel, or can make the second inclined groove block both the second inlet channel and the second return channel. The second internal pressure chamber is connected with the second inlet channel.

[0010] By driving the first rotating shaft to rotate, the first inclined groove is selectively connected to either the first inlet channel or the first return channel, thereby changing the oil pressure in the first external pressure chamber. When the inlet channel is connected to the first inclined groove, the oil pressure in the first external pressure chamber increases, thereby increasing the force exerted by the pressure oil on the first valve core to the right. The force exerted by the first external pressure chamber on the first valve core is greater than the force exerted by the first internal pressure chamber and / or the pressure oil port on the first valve core. The first valve core moves to the right and drives the first rotating shaft to move to the right. Because it is an inclined groove, the rightward movement along the axial direction will gradually reduce the opening of the first inlet channel until it reaches 0 and stops moving to the right. When the first return channel is connected to the first inclined groove, the oil pressure in the first external pressure chamber decreases, thereby reducing the force exerted by the pressure oil on the first valve core to the right. The force exerted by the first external pressure chamber on the first valve core is less than the force exerted by the first internal pressure chamber and / or the pressure oil port on the first valve core. The first valve core can move to the left and drive the first rotating shaft to move to the left. The leftward movement along the axial direction will gradually reduce the opening of the first inlet channel until it reaches 0 and stops moving upward. A larger rotation angle results in a longer axial travel. The rotation angle determines the travel. The first rotating shaft moves axially with the first valve core without axial slippage or friction, simplifying assembly, significantly improving product yield, and enhancing mating stability, thus greatly reducing the failure rate. This drive mechanism only needs to control the first rotating shaft within a 90-degree or even smaller angle range. A servo motor can control the maximum stroke displacement of the piston, with speed and time often completed in milliseconds, exhibiting excellent dynamic response characteristics. Furthermore, the core components of this drive mechanism are the first rotating shaft and the first valve core, with a simple interrelationship, resulting in low cost and a simple, reasonable structure. Driving the rotation of the first rotating shaft requires only a small force; a servo motor can easily drive it, requiring far less energy than directly driving a large-diameter first valve core, making it more energy-efficient. The rotation angle of the first rotating shaft controls the axial travel distance of the first valve core, thereby controlling the opening degree of each port of the directional valve.

[0011] In a further improvement, the first external pressure chamber is equipped with a first external spring acting on the first valve core, and the first internal pressure chamber is equipped with a first internal spring acting on the first valve core; the second external pressure chamber is equipped with a second external spring acting on the second valve core, and the second internal pressure chamber is equipped with a second internal spring acting on the second valve core. The springs on both sides provide a balancing effect, ensuring that the first valve core can return to its initial position when there is no pressure in any chamber. The springs also buffer the left and right movement of the first valve core.

[0012] As an improvement, the output shaft of the first motor is connected to the first rotating shaft via a first transmission joint. The first transmission joint and the first rotating shaft are connected by a shaft groove structure. The shaft groove structure includes a vertically extending first sliding groove and a first driving shaft that can slide up and down within the first sliding groove. The first sliding groove is located in one of the first transmission joint and the first rotating shaft, and the first driving shaft is located in the other of the first transmission joint and the first rotating shaft. Similarly, the output shaft of the second motor is connected to the second rotating shaft via a second transmission joint. The second transmission joint and the second rotating shaft are connected by a shaft groove structure. The shaft groove structure includes a vertically extending second sliding groove and a second driving shaft that can slide up and down within the second sliding groove. The second sliding groove is located in one of the second transmission joint and the second rotating shaft, and the second driving shaft is located in the other of the second transmission joint and the second rotating shaft. This ensures that the motor can both drive the first rotating shaft to rotate and allow the first rotating shaft to move axially relative to the motor.

[0013] In a further improvement, a first oil passage sleeve is fixed inside the aforementioned first transition shaft. The first oil passage sleeve has a first oil inlet spiral hole and a first oil outlet spiral hole. The first inlet channel is always connected to the first oil inlet spiral hole, and the first return channel is always connected to the first oil outlet spiral hole. The first rotating shaft passes through the first oil passage sleeve and can rotate around its own axis. The first inclined groove is connected to the first inlet channel through the first oil inlet spiral hole, and to the first return channel through the first oil outlet spiral hole. The first inclined groove can also simultaneously connect to both the first oil inlet spiral hole and the first oil outlet spiral hole. A spiral hole is used for blocking; a second oil passage sleeve is fixed inside the aforementioned second transition shaft. The second oil passage sleeve has a second oil inlet spiral hole and a second oil outlet spiral hole. The second inflow channel is always connected to the second oil inlet spiral hole, and the second return channel is always connected to the second oil outlet spiral hole. The second rotating shaft passes through the second oil passage sleeve and can rotate around its own axis. The second inclined groove is connected to the second inflow channel through the second oil inlet spiral hole, and to the second return channel through the second oil outlet spiral hole. The second inclined groove can also block both the second oil inlet spiral hole and the second oil outlet spiral hole simultaneously. During the axial movement of the first rotating shaft, the spiral hole increases the oil inlet area.

[0014] As an improvement, the left end of the first valve core is provided with a first mounting cavity, and the right end of the first rotating shaft is installed in the first mounting cavity. The outer peripheral wall of the first rotating shaft is provided with a first annular shoulder, and a first sealing ring is provided between the first rotating shaft and the inner peripheral wall of the first mounting cavity. Since it is impossible to achieve a complete seal in the valve assembly, there will always be oil leakage. If hydraulic oil leaks into the first mounting cavity, it will push the first rotating shaft and the first valve core to slide axially relative to each other. If the first valve core is pushed open, the control will be affected. To solve this problem, the first mounting cavity is connected to the oil return port through a first pressure relief channel on the first valve core. Because the first mounting cavity is connected to the first pressure relief channel, and the first pressure relief channel is connected to the low-pressure area, it ensures that the first mounting cavity to the right of the first rotating shaft is always at low pressure. The oil pressure can act on the annular shoulder with a very small cross-sectional area, applying a force to the first rotating shaft to move in the direction of the first valve core, so as to better ensure that the first rotating shaft can move axially with the first valve core. Similarly, the left end of the second valve core is provided with a second mounting cavity, the right end of the second rotating shaft is mounted in the second mounting cavity, the outer peripheral wall of the second rotating shaft is provided with a second annular shoulder, a second sealing ring is provided between the second rotating shaft and the inner peripheral wall of the second mounting cavity, and the second mounting cavity is connected to the oil return port through the second pressure relief channel on the second valve core. Preferably, a first ball bearing is provided between the bottom surface of the first rotating shaft and the bottom surface of the first mounting cavity. The first ball bearing makes the rotation of the first rotating shaft easier. Similarly, a second ball bearing is provided between the bottom surface of the second rotating shaft and the bottom surface of the second mounting cavity.

[0015] Because back pressure may exist at the oil return port, and the oil flow rate may reach tens of kilograms per kilogram during rapid peak flows, to prevent pressurized oil in the oil return port from flowing into the first mounting chamber through the first pressure relief channel, a first check valve is installed in the first pressure relief channel as an improvement. When the pressure in the first mounting chamber is greater than the back pressure at the oil return port, the first check valve opens to release the oil pressure in the first mounting chamber through the first pressure relief channel. The first check valve can only be opened to release oil when the back pressure at the oil return port is below 2-3 kilograms. Similarly, a third check valve is installed in the second pressure relief channel. When the pressure in the second mounting chamber is greater than the back pressure at the oil return port, the third check valve opens to release the oil pressure in the second mounting chamber through the second pressure relief channel.

[0016] The second technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a dual-valve-core reversing valve, comprising a valve body and a valve core, wherein the valve body is provided with a valve core cavity and a pressure oil port, a return oil port, a first oil port and a second oil port communicating with the valve core cavity, the valve core being disposed in the valve core cavity and capable of axial movement; there are two valve cores, namely a first valve core and a second valve core coaxially arranged, the first valve core being driven by a first driving structure and capable of axial movement, the second valve core being driven by a second driving structure and capable of axial movement, the first valve core and the second valve core being capable of relative axial movement; the axial movement of the first valve core can cause the first oil port to communicate with the pressure oil port or the return oil port, or cause the first oil port to block both the pressure oil port and the return oil port; the axial movement of the second valve core can cause the second oil port to communicate with the pressure oil port or the return oil port, or cause the second oil port to block both the pressure oil port and the return oil port; the first driving structure includes a first control cavity located on the left side of the valve core cavity, and the outer end of the first valve core has a protruding first annular shoulder. The outer end of the first valve core extends into the first control chamber and divides the first control chamber into a first external pressure chamber and a first internal pressure chamber. Oil inflow and outflow through the first external pressure chamber and the first internal pressure chamber drive the axial movement of the first valve core. The area of ​​the pressure oil in the first external pressure chamber acting on the first valve core is greater than the sum of the area of ​​the pressure oil in the first internal pressure chamber acting on the first valve core and the area acting on the first valve core after entering the valve core cavity through the pressure oil port. The second drive structure includes a second control chamber located on the right side of the valve core cavity. The outer end of the second valve core has a protruding second annular shoulder. The outer end of the second valve core extends into the second control chamber and divides the second control chamber into a second external pressure chamber and a second internal pressure chamber. Oil inflow and outflow through the second external pressure chamber and the second internal pressure chamber drive the axial movement of the second valve core. The area of ​​the pressure oil in the second external pressure chamber acting on the second valve core is greater than the sum of the area of ​​the pressure oil in the second pressure chamber acting on the second valve core and the area acting on the second valve core after entering the valve core cavity through the pressure oil port.

[0017] Compared with existing technologies, the advantages of the first technical solution of this directional valve are: 1. The system adopts a dual-valve-core structure with a coaxially arranged first and second valve core. The first and second valve cores are controlled by their respective independent drive structures, ensuring that the control of the two valve cores does not interfere with each other. This allows for independent and perfect control of the controlled working chambers. A single dual-core valve can realize a differential circuit and can also perform closed-loop pressure control of two chambers of a cylinder or hydraulic motor. This enables precise control of the output torque, overcoming friction and other forces. Furthermore, it can be combined to create various functional controls and valve core control with logic control. Specifically, when this directional valve is used in a hydraulic system, one directional valve is equivalent to the function of multiple existing valve combinations, simplifying the hydraulic system, making the hydraulic circuit simpler, and achieving precise and accurate control, while reducing costs and failure rates.

[0018] 2. This drive structure uses hydraulic power to achieve the drive. When oil enters the first external pressure chamber, the area of ​​the pressure oil in the first external pressure chamber acting on the first valve core is greater than the sum of the area of ​​the pressure oil in the first pressure chamber acting on the first valve core and the area acting on the first valve core after entering the valve core cavity through the pressure oil port. Therefore, regardless of whether oil enters the pressure oil port, the first valve core can be driven to move to the right. When oil is discharged from the first external pressure chamber, the first valve core can move to the left under the oil pressure of the first internal pressure chamber and / or the pressure oil port. When the pressure oil enters the first external pressure chamber and closes, the first valve core can be kept in the position after moving to the right.

[0019] 3. The inner ends of the first valve core and the second valve core are interlocked, which can more accurately ensure the coaxial relative displacement of the two valve cores and achieve higher control precision.

[0020] The second technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a dual-valve-core reversing valve, comprising a valve body and a valve core, wherein the valve body is provided with a valve core cavity and a pressure oil port, a return oil port, a first oil port and a second oil port communicating with the valve core cavity, the valve core being disposed in the valve core cavity and capable of axial movement; there are two valve cores, namely a first valve core and a second valve core coaxially arranged, the first valve core being driven by a first driving structure and capable of axial movement, the second valve core being driven by a second driving structure and capable of axial movement, the first valve core and the second valve core being capable of relative axial movement; the axial movement of the first valve core can cause the first oil port to communicate with the pressure oil port or the return oil port, or cause the first oil port to block both the pressure oil port and the return oil port; the axial movement of the second valve core can cause the second oil port to communicate with the pressure oil port or the return oil port, or cause the second oil port to block both the pressure oil port and the return oil port; the first driving structure includes a first control cavity located on the left side of the valve core cavity, the outer end of the first valve core having an outwardly protruding first annular shoulder, the second... A valve core has its outer end extending into a first control chamber, which divides the first control chamber into a first external pressure chamber and a first internal pressure chamber. Oil is introduced and returned through the first external pressure chamber and the first internal pressure chamber, driving the axial movement of the first valve core. The area of ​​the pressure oil in the first external pressure chamber acting on the first valve core is greater than the sum of the area of ​​the pressure oil in the first internal pressure chamber acting on the first valve core and the area acting on the first valve core after entering the valve core cavity through the pressure oil port. A second drive structure includes a second control chamber located on the right side of the valve core cavity. The outer end of the second valve core has a protruding second annular shoulder. The outer end of the second valve core extends into the second control chamber, dividing the second control chamber into a second external pressure chamber and a second internal pressure chamber. Oil is introduced and returned through the second external pressure chamber and the second internal pressure chamber, driving the axial movement of the second valve core. The area of ​​the pressure oil in the second external pressure chamber acting on the second valve core is greater than the sum of the area of ​​the pressure oil in the second pressure chamber acting on the second valve core and the area acting on the second valve core after entering the valve core cavity through the pressure oil port.

[0021] Compared with the prior art, the advantages of the second technical solution of this reversing valve are: advantages 1 and advantages 2 in the first embodiment can be referred to. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of the first embodiment of the present invention. Figure 1 ; Figure 2 This is a three-dimensional structural diagram of the first embodiment of the present invention. Figure 2 ; Figure 3 This is a cross-sectional view along the central axis of the rotation axis of the first embodiment of the present invention; Figure 4 for Figure 3 Enlarged view of point C; Figure 5 for Figure 3 Enlarged view of point D; Figure 6 This is a cross-sectional view along the axis of the inflow channel of the first embodiment of the present invention; Figure 7 This is a partial three-dimensional schematic diagram of the driving structure after removing the transition axis in the first embodiment of the present invention; Figure 8 This is an exploded perspective view of the top-down drive structure of the first embodiment of the present invention after removing the transition axis; Figure 9 This is a three-dimensional structural diagram of the transition shaft in the first embodiment of the present invention; Figure 10 This is a three-dimensional structural diagram of the first valve core in the first embodiment of the present invention; Figure 11 This is a three-dimensional structural diagram of the second valve core in the first embodiment of the present invention; Figure 12 This is a cross-sectional view along the central axis of the rotation axis of the second embodiment of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figures 1-11 The image shown is the first preferred embodiment of the present invention.

[0025] A dual-spool directional control valve includes a valve body 1 and a valve spool. The valve body 1 has a valve spool cavity and a pressure port P, a return port T, a first port A, and a second port B communicating with the valve spool cavity. The pressure port P is located in the middle, and the first port A and the second port B are located on the left and right sides of the pressure port P and are adjacent to each other. There are two return ports T located on the outermost sides. A connecting channel 11 connecting the two return ports T is provided above the valve spool cavity. The valve spool is disposed within the valve spool cavity and can move axially. In this embodiment, the pressure port P, return port T, first port A, and second port B appear to be located in a plane in the drawings; this is for ease of illustration. In reality, the pressure port P, return port T, first port A, and second port B can be offset from each other.

[0026] There are two valve cores, namely a first valve core 2a and a second valve core 2b, which are coaxially arranged. The first valve core 2a is driven by a first driving structure and can move axially. In this embodiment, the axial movement is left and right as shown in the figure. The second valve core 2b is driven by a second driving structure and can move axially. The inner ends of the first valve core 2a and the second valve core 2b are interlocked. The first valve core 2a and the second valve core 2b can move axially relative to each other. The axial movement of the first valve core 2a can make the first oil port A connected to the pressure oil port P or the return oil port T, or make the first oil port A blocked from both the pressure oil port P and the return oil port T. The axial movement of the second valve core 2b can make the second oil port B connected to the pressure oil port P or the return oil port T, or make the second oil port B blocked from both the pressure oil port P and the return oil port T.

[0027] The inner end of the first valve core 2a is provided with a concave guide cavity 2a1, and the inner end of the second valve core 2b is provided with a guide post 2b1 for inserting into the guide cavity 2a1. A sealing structure is provided between the outer periphery of the guide post 2b1 and the inner wall of the guide cavity 2a1. The second valve core 2b has a second pressure relief channel 2b4 that connects the guide cavity 2a1 and the oil return port T. A second check valve 3b is provided in the second pressure relief channel 2b4. When the pressure in the guide cavity 2a1 is greater than the back pressure of the oil return port T, the second check valve 3b opens to release the oil pressure in the guide cavity 2a1 through the second pressure relief channel 2b4.

[0028] In this embodiment, the first driving structure includes a first control chamber located on the left side of the valve core cavity. The outer end of the first valve core 2a has a protruding first annular shoulder 2a2. The outer end of the first valve core 2a extends into the first control chamber and divides the first control chamber into a first external pressure chamber 5a and a first internal pressure chamber 5b. A first external spring 10a acting on the first valve core 2a is provided in the first external pressure chamber 5a, and a first internal spring 10b acting on the first valve core 2a is provided in the first internal pressure chamber 5b. The axial movement of the first valve core 2a is driven by the oil inlet and outlet of the first external pressure chamber 5a and the first internal pressure chamber 5b. The area of ​​the pressure oil in the first external pressure chamber 5a acting on the first valve core 2a is greater than the sum of the area of ​​the pressure oil in the first internal pressure chamber 5b acting on the first valve core 2a and the area acting on the first valve core 2a after entering the valve core cavity through the pressure oil port P.

[0029] A first transition shaft 6a is fixed inside the first external pressure chamber 5a. The first transition shaft 6a and the valve body 1 are provided with a first inlet channel P1 and a first return channel T1. A first rotating shaft 7a that can rotate around its own axis is inserted inside the first transition shaft 6a. The first rotating shaft 7a is controlled to rotate by a first motor 8a. A first inclined groove 7a1 that communicates with the first external pressure chamber 5a is provided on the outer peripheral wall of the first rotating shaft 7a. The rotation of the first rotating shaft 7a can make the first inclined groove 7a1 communicate with one of the first inlet channel P1 and the first return channel T1, or can make the first inclined groove 7a1 block both the first inlet channel P1 and the first return channel T1. The first internal pressure chamber 5b is connected to the first inlet channel P1.

[0030] The output shaft of the first motor 8a is connected to the first rotating shaft 7a through the first transmission joint 9a. The first transmission joint 9a and the first rotating shaft 7a are connected by a shaft groove structure. The shaft groove structure includes a vertically extending first sliding groove 9a1 and a first driving shaft 7a2 that can slide up and down in the first sliding groove 9a1. The first sliding groove 9a1 is provided on the first transmission joint 9a, and the first driving shaft 7a2 is provided on the first rotating shaft 7a.

[0031] A first oil passage sleeve 4a is fixed inside the first transition shaft 6a. The first oil passage sleeve 4a has a first oil inlet spiral hole 4a1 and a first oil outlet spiral hole 4a2. The first inlet channel P1 is always connected to the first oil inlet spiral hole 4a1, and the first return channel T1 is always connected to the first oil outlet spiral hole 4a2. The first rotating shaft 7a passes through the first oil passage sleeve 4a and can rotate around its own axis. The first inclined groove 7a1 is connected to the first inlet channel P1 through the first oil inlet spiral hole 4a1, and the first inclined groove 7a1 is connected to the first return channel T1 through the first oil outlet spiral hole 4a2. The first inclined groove 7a1 can also block the first oil inlet spiral hole 4a1 and the first oil outlet spiral hole 4a2 at the same time.

[0032] The left end of the first valve core 2a has a first mounting cavity 2a3, and the right end of the first rotating shaft 7a is installed in the first mounting cavity 2a3. The outer peripheral wall of the first rotating shaft 7a has a first annular shoulder 7a3. A first sealing ring 12a is provided between the first rotating shaft 7a and the inner peripheral wall of the first mounting cavity 2a3. The first mounting cavity 2a3 is connected to the oil return port T through a first pressure relief channel 2a4 on the first valve core 2a. A first ball bearing 13a is provided between the bottom surface of the first rotating shaft 7a and the bottom surface of the first mounting cavity 2a3. A first check valve 3a is provided in the first pressure relief channel 2a4. When the pressure in the first mounting cavity 2a3 is greater than the back pressure of the oil return port T, the first check valve 3a opens to release the oil pressure in the first mounting cavity 2a3 through the first pressure relief channel 2a4.

[0033] The second drive structure includes a second control chamber located on the right side of the valve core cavity. The outer end of the second valve core 2b has a protruding second annular shoulder 2b2. The outer end of the second valve core 2b extends into the second control chamber and divides the second control chamber into a second external pressure chamber 5c and a second internal pressure chamber 5d. A second external spring 10c acting on the second valve core 2b is provided in the second external pressure chamber 5c, and a second internal spring 10d acting on the second valve core 2b is provided in the second internal pressure chamber 5d. The axial movement of the second valve core 2b is driven by the oil entering and exiting the second external pressure chamber 5c and the second internal pressure chamber 5d. The area of ​​the pressure oil in the second external pressure chamber 5c acting on the second valve core 2b is greater than the sum of the area of ​​the pressure oil in the second pressure chamber 1b acting on the second valve core 2b and the area acting on the second valve core 2b after entering the valve core cavity through the pressure oil port P.

[0034] A second transition shaft 6b is fixed inside the second external pressure chamber 5c. The second transition shaft 6b and the valve body 1 are provided with a second inlet channel P2 and a second return channel T2. A second rotating shaft 7b that can rotate around its own axis is inserted inside the second transition shaft 6b. The rotation of the second rotating shaft 7b is controlled by a second motor 8b. A second inclined groove 7b1 that communicates with the second external pressure chamber 5c is provided on the outer peripheral wall of the second rotating shaft 7b. The rotation of the second rotating shaft 7b can make the second inclined groove 7b1 communicate with one of the second inlet channel P2 and the second return channel T2, or can make the second inclined groove 7b1 block both the second inlet channel P2 and the second return channel T2. The second internal pressure chamber 5d is connected to the second inlet channel P2.

[0035] The output shaft of the second motor 8b is connected to the second rotating shaft 7b via the second transmission joint 9b. The second transmission joint 9b and the second rotating shaft 7b are connected by a shaft groove structure. The shaft groove structure includes a vertically extending second slide groove 9b1 and a second drive shaft 7b2 that can slide up and down in the second slide groove 9b1. The second slide groove 9b1 is provided on the second transmission joint 9b, and the second drive shaft 7b2 is provided on the second rotating shaft 7b.

[0036] A second oil passage sleeve 4b is fixed inside the second transition shaft 6b. The second oil passage sleeve 4b has a second oil inlet spiral hole 4b1 and a second oil outlet spiral hole 4b2. The second inlet channel P2 is always connected to the second oil inlet spiral hole 4b1, and the second return channel T2 is always connected to the second oil outlet spiral hole 4b2. The second rotating shaft 7b passes through the second oil passage sleeve 4b and can rotate around its own axis. The second inclined groove 7b1 is connected to the second inlet channel P2 through the second oil inlet spiral hole 4b1 and to the second return channel T2 through the second oil outlet spiral hole 4b2. The second inclined groove 7b1 can also block the second oil inlet spiral hole 4b1 and the second oil outlet spiral hole 4b2 at the same time.

[0037] The left end of the second valve core 2b is provided with a second mounting cavity 2b3, and the right end of the second rotating shaft 7b is mounted in the second mounting cavity 2b3. A second annular shoulder 7b3 is provided on the outer peripheral wall of the second rotating shaft 7b. A second sealing ring 12b is provided between the second rotating shaft 7b and the inner peripheral wall of the second mounting cavity 2b3. The second mounting cavity 2b3 is connected to the oil return port T through a second pressure relief channel 2b4 on the second valve core 2b. A second ball bearing 13b is provided between the bottom surface of the second rotating shaft 7b and the bottom surface of the second mounting cavity 2b3. A third check valve 3c is provided in the second pressure relief channel 2b4. When the pressure in the second mounting cavity 2b3 is greater than the back pressure of the oil return port T, the third check valve 3c opens to release the oil pressure in the second mounting cavity 2b3 through the second pressure relief channel 2b4.

[0038] This directional control valve adopts a dual-valve-core structure with a first valve core 2a and a second valve core 2b arranged coaxially. The first valve core 2a and the second valve core 2b are controlled by their respective independent drive structures. The control of the two valve cores does not interfere with each other and can be combined to perform multiple control functions. Specifically, when this directional control valve is used in a hydraulic system, one directional control valve is equivalent to the function of multiple existing valve combinations, simplifying the hydraulic system, making the hydraulic oil circuit simpler, and reducing costs and failure rates.

[0039] The initial position pressure port P, return port T, first port A and second port B are all blocked from each other.

[0040] The driving process of the first valve core 2a: The first motor 8a drives the first rotating shaft 7a to rotate in the forward direction, so that the first inclined groove 7a1 is connected to the first inlet channel P1, and the first inlet channel P1 is connected to the first inner pressure chamber 5b. The oil pressure in the first outer pressure chamber 5a and the first inner pressure chamber 5b increases. Since the area of ​​the pressure oil in the first outer pressure chamber 5a acting on the first valve core 2a is greater than the sum of the area of ​​the pressure oil in the first inner pressure chamber 5b acting on the first valve core 2a and the area acting on the first valve core 2a after entering the valve core cavity through the pressure oil port P, the force of the first outer pressure chamber 5a acting on the first valve core 2a is greater than the sum of the area of ​​the pressure oil in the first inner pressure chamber 5b and the area of ​​the pressure oil in the first inner pressure chamber 5b acting on the first valve core 2a. The force exerted by the oil port P on the first valve core 2a drives the first valve core 2a to move to the right and drives the first rotating shaft 7a to move to the right. Because the first inclined groove 7a1 is an inclined groove, the opening of the first rotating shaft 7a along the axial direction gradually decreases until it stops moving to the right at 0, and the first valve core 2a remains in this position. The return oil port T and the first oil port A are connected. The distance of the axial movement of the first valve core 2a is controlled by the rotation angle of the first rotating shaft 7a. The larger the rotation angle of the first rotating shaft 7a, the longer the axial movement of the first valve core 2a, which can realize the control of the degree of connection between the return oil port T and the first oil port A.

[0041] The first motor 8a drives the first rotating shaft 7a to rotate in the opposite direction, connecting the first return channel T1 with the first inclined groove 7a1 and the first inlet channel P1 with the first inner pressure chamber 5b. The oil pressure in the first outer pressure chamber 5a decreases, while the oil pressure in the first inner pressure chamber 5b increases. This drives the first valve core 2a to move to the left, which in turn drives the first rotating shaft 7a to move to the left. As the first rotating shaft 7a moves to the left along its axis, the opening of the first inlet channel P1 gradually decreases until it reaches zero and stops moving upwards. The first valve core 2a remains in this position, connecting the pressure port P and the first port A. The axial movement distance of the first valve core 2a is controlled by the rotation angle of the first rotating shaft 7a. The larger the rotation angle of the first rotating shaft 7a, the longer the axial movement of the first valve core 2a, thus controlling the degree of connection between the pressure port P and the first port A.

[0042] When oil leaks into the first mounting chamber 2a3, causing the pressure inside the first mounting chamber 2a3 to exceed the back pressure at the oil return port T, the first check valve 3a opens to release the oil pressure inside the first mounting chamber 2a3 through the first pressure relief channel 2a4.

[0043] The driving process of the second valve core 2b: The second motor 8b drives the second rotating shaft 7b to rotate in the forward direction, so that the second inclined groove 7b1 is connected to the second inlet channel P2, and the second inlet channel P2 is connected to the second inner pressure chamber 5d. The oil pressure in the second outer pressure chamber 5c and the second inner pressure chamber 5d increases. Since the area of ​​the pressure oil in the second outer pressure chamber 5b acting on the second valve core 2b is greater than the sum of the area of ​​the pressure oil in the second inner pressure chamber 5d acting on the second valve core 2b after entering the valve core cavity through the pressure oil port P, the force of the second outer pressure chamber 5c acting on the second valve core 2b is greater than the sum of the area of ​​the pressure oil in the second inner pressure chamber 5d and the area of ​​the pressure oil in the second inner pressure chamber 5d acting on the second valve core 2b. The force exerted by the oil port P on the second valve core 2b drives the second valve core 2b to move to the left and drives the second rotating shaft 7b to move to the left. Because the second inclined groove 7b1 is an inclined groove, the second rotating shaft 7b moves to the left along the axial direction, and at the same time, the opening of the second inclined groove 7b1 and the second inlet channel P2 gradually decreases until it stops moving to the right. The second valve core 2b remains in this position, and the return oil port T and the second oil port B are connected. The distance of the axial movement of the second valve core 2b is controlled by the size of the rotation angle of the second rotating shaft 7b. The larger the rotation angle of the second rotating shaft 7b, the longer the stroke of the second valve core 2b in the axial direction, which can realize the control of the degree of connection between the return oil port T and the second oil port B.

[0044] The second motor 8b drives the second rotating shaft 7b to rotate in the opposite direction, connecting the second return channel T2 with the second inclined groove 7b1 and the second inlet channel P2 with the second inner pressure chamber 5d. The oil pressure in the second outer pressure chamber 5c decreases, while the oil pressure in the first inner pressure chamber 5d increases. This drives the second valve core 2b to move to the left, which in turn drives the second rotating shaft 7b to move to the left. As the second rotating shaft 7b moves to the right along its axis, the opening of the second inlet channel P2 gradually decreases until it reaches zero and stops moving upwards. The second valve core 2b remains in this position, connecting the pressure port P and the second port B. The axial movement distance of the second valve core 2b is controlled by the rotation angle of the second rotating shaft 7b. The larger the rotation angle of the second rotating shaft 7b, the longer the axial movement of the second valve core 2b, thus controlling the degree of connection between the pressure port P and the second port B.

[0045] When oil leaks into the guide chamber 2a1, causing the pressure inside the guide chamber 2a1 to exceed the back pressure at the return port T, the second check valve 3b opens to release the oil pressure in the guide chamber 2a1 through the second pressure relief channel 2b4. When oil leaks into the second mounting chamber 2b3, causing the pressure inside the second mounting chamber 2b3 to exceed the back pressure at the oil return port T, the second check valve 3b opens to release the oil pressure inside the second mounting chamber 2b3 through the second pressure relief channel 2b4.

[0046] like Figure 12 As shown, this is the second preferred embodiment of the present invention.

[0047] The difference between this embodiment and the first embodiment is that the inner ends of the first valve core 2a and the second valve core 2b are not interlocked. They are spaced apart from each other. Furthermore, there is no need to provide corresponding pressure relief channels and check valves within the first valve core 2a and the second valve core 2b.

[0048] It should be noted that in the description of this embodiment, the terms "front," "rear," "left," "right," "inner," "outer," "upper," and "lower," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A dual-spool directional control valve, comprising a valve body (1) and a valve spool, wherein the valve body (1) is provided with a valve spool cavity and a pressure port (P), a return port (T), a first port (A), and a second port (B) communicating with the valve spool cavity, and the valve spool is disposed within the valve spool cavity and is axially movable; characterized in that: The valve core consists of two parts: a first valve core (2a) and a second valve core (2b) coaxially arranged. The first valve core (2a) is driven axially by a first driving structure, and the second valve core (2b) is driven axially by a second driving structure. The inner ends of the first valve core (2a) and the second valve core (2b) are interlocked, and the first valve core (2a) and the second valve core (2b) can move axially relative to each other. The axial movement of the first valve core (2a) can connect the first oil port (A) with the pressure oil port (P) or the return oil port (T), or block the first oil port (A) from both the pressure oil port (P) and the return oil port (T). The axial movement of the second valve core (2b) can connect the second oil port (B) with the pressure oil port (P) or the return oil port (T), or block the second oil port (B) from both the pressure oil port (P) and the return oil port (T). The first driving structure includes a first control chamber located on the left side of the valve core cavity. The outer end of the first valve core (2a) has a first annular shoulder (2a2) that protrudes outward. The outer end of the first valve core (2a) extends into the first control chamber and divides the first control chamber into a first external pressure chamber (5a) and a first internal pressure chamber (5b). The axial movement of the first valve core (2a) is driven by the oil inlet and outlet of the first external pressure chamber (5a) and the first internal pressure chamber (5b). The area of ​​the pressure oil in the first external pressure chamber (5a) acting on the first valve core (2a) is greater than the sum of the area of ​​the pressure oil in the first internal pressure chamber (5b) acting on the first valve core (2a) and the area acting on the first valve core (2a) after entering the valve core cavity through the pressure oil port (P). The second drive structure includes a second control chamber located on the right side of the valve core cavity. The outer end of the second valve core (2b) has a protruding second annular shoulder (2b2). The outer end of the second valve core (2b) extends into the second control chamber and divides the second control chamber into a second external pressure chamber (5c) and a second internal pressure chamber (5d). The axial movement of the second valve core (2b) is driven by the oil inlet and outlet of the second external pressure chamber (5c) and the second internal pressure chamber (5d). The area of ​​the pressure oil in the second external pressure chamber (5c) acting on the second valve core (2b) is greater than the sum of the area of ​​the pressure oil in the second pressure chamber (1b) acting on the second valve core (2b) and the area acting on the second valve core (2b) after entering the valve core cavity through the pressure oil port (P).

2. The dual-core directional valve according to claim 1, characterized in that: The first valve core (2a) has a recessed guide cavity (2a1) at its inner end, and the second valve core (2b) has a guide post (2b1) at its inner end for inserting into the guide cavity (2a1). A sealing structure is provided between the outer periphery of the guide post (2b1) and the inner wall of the guide cavity (2a1). The second valve core (2b) has a second pressure relief channel (2b4) connecting the guide cavity (2a1) and the oil return port (T), and a second check valve (3b) is provided in the second pressure relief channel (2b4). When the pressure in the guide cavity (2a1) is greater than the back pressure of the return port (T), the second check valve (3b) opens to release the oil pressure in the guide cavity (2a1) through the second pressure relief channel (2b4); the pressure port (P) is located in the middle position, the first port (A) and the second port (B) are located on the left and right sides of the pressure port (P) and are adjacent to each other, there are two return ports (T) located on the outermost sides respectively, and a connecting channel (11) connecting the two return ports (T) is provided above the valve core cavity.

3. The dual-core directional valve according to claim 1, characterized in that: A first transition shaft (6a) is fixed inside the first external pressure chamber (5a). The first transition shaft (6a) and the valve body (1) are provided with a first inlet channel (P1) and a first return channel (T1). A first rotating shaft (7a) capable of rotating around its own axis is inserted inside the first transition shaft (6a). The first rotating shaft (7a) is controlled to rotate by a first motor (8a). A first inclined groove (7a1) communicating with the first external pressure chamber (5a) is provided on the outer peripheral wall of the first rotating shaft (7a). The rotation of the first rotating shaft (7a) can make the first inclined groove (7a1) communicate with one of the first inlet channel (P1) and the first return channel (T1), or can make the first inclined groove (7a1) block both the first inlet channel (P1) and the first return channel (T1). The first internal pressure chamber (5b) is connected to the first inlet channel (P1). A second transition shaft (6b) is fixed inside the second external pressure chamber (5c). The second transition shaft (6b) and the valve body (1) are provided with a second inlet channel (P2) and a second return channel (T2). A second rotating shaft (7b) that can rotate around its own axis is inserted inside the second transition shaft (6b). The second rotating shaft (7b) is controlled to rotate by a second motor (8b). A second inclined groove (7b1) communicating with the second external pressure chamber (5c) is provided on the outer peripheral wall of the second rotating shaft (7b). The rotation of the second rotating shaft (7b) can make the second inclined groove (7b1) communicate with one of the second inlet channel (P2) and the second return channel (T2), or can make the second inclined groove (7b1) block both the second inlet channel (P2) and the second return channel (T2). The second internal pressure chamber (5d) is connected to the second inlet channel (P2).

4. The dual-core directional valve according to claim 1, characterized in that: The first external pressure chamber (5a) is provided with a first external spring (10a) acting on the first valve core (2a), and the first internal pressure chamber (5b) is provided with a first internal spring (10b) acting on the first valve core (2a); The second external pressure chamber (5c) is provided with a second external spring (10c) acting on the second valve core (2b), and the second internal pressure chamber (5d) is provided with a second internal spring (10d) acting on the second valve core (2b).

5. The dual-core directional valve according to claim 1, characterized in that: The output shaft of the first motor (8a) is connected to the first rotating shaft (7a) through the first transmission joint (9a). The first transmission joint (9a) and the first rotating shaft (7a) are connected by a shaft groove structure. The shaft groove structure includes a vertically extending first sliding groove (9a1) and a first driving shaft (7a2) that can slide up and down in the first sliding groove (9a1). The first sliding groove (9a1) is provided in one of the first transmission joint (9a) and the first rotating shaft (7a), and the first driving shaft (7a2) is provided in the other of the first transmission joint (9a) and the first rotating shaft (7a). The output shaft of the second motor (8b) is connected to the second rotating shaft (7b) via the second transmission joint (9b). The second transmission joint (9b) and the second rotating shaft (7b) are connected by a shaft groove structure. The shaft groove structure includes a vertically extending second slide groove (9b1) and a second drive shaft (7b2) that can slide up and down in the second slide groove (9b1). The second slide groove (9b1) is located in one of the second transmission joint (9b) and the second rotating shaft (7b), and the second drive shaft (7b2) is located in the other of the second transmission joint (9b) and the second rotating shaft (7b).

6. The dual-core directional valve according to claim 1, characterized in that: A first oil passage sleeve (4a) is fixed inside the first transition shaft (6a). The first oil passage sleeve (4a) has a first oil inlet spiral hole (4a1) and a first oil outlet spiral hole (4a2). The first inlet channel (P1) is always connected to the first oil inlet spiral hole (4a1). The first return channel (T1) is always connected to the first oil outlet spiral hole (4a2). The first rotating shaft (7a) passes through the first oil passage sleeve (4a) and can rotate around its own axis. The first inclined groove (7a1) is connected to the first inlet channel (P1) through the first oil inlet spiral hole (4a1). The first inclined groove (7a1) is connected to the first return channel (T1) through the first oil outlet spiral hole (4a2). The first inclined groove (7a1) can also block the first oil inlet spiral hole (4a1) and the first oil outlet spiral hole (4a2) at the same time. A second oil passage sleeve (4b) is fixed inside the second transition shaft (6b). The second oil passage sleeve (4b) has a second oil inlet spiral hole (4b1) and a second oil outlet spiral hole (4b2). The second inflow channel (P2) is always connected to the second oil inlet spiral hole (4b1), and the second return channel (T2) is always connected to the second oil outlet spiral hole (4b2). The second rotating shaft (7b) is inserted inside the second oil passage sleeve (4b) and can rotate around its own axis. The second inclined groove (7b1) is connected to the second inflow channel (P2) through the second oil inlet spiral hole (4b1) and to the second return channel (T2) through the second oil outlet spiral hole (4b2). The second inclined groove (7b1) can also block the second oil inlet spiral hole (4b1) and the second oil outlet spiral hole (4b2) at the same time.

7. The dual-core directional valve according to claim 1, characterized in that: The left end of the first valve core (2a) is provided with a first mounting cavity (2a3), the right end of the first rotating shaft (7a) is installed in the first mounting cavity (2a3), the outer peripheral wall of the first rotating shaft (7a) is provided with a first annular shoulder (7a3), a first sealing ring (12a) is provided between the first rotating shaft (7a) and the inner peripheral wall of the first mounting cavity (2a3), and the first mounting cavity (2a3) is connected to the return oil port (T) through the first pressure relief channel (2a4) on the first valve core (2a); The second valve core (2b) has a second mounting cavity (2b3) at its left end, and the right end of the second rotating shaft (7b) is mounted in the second mounting cavity (2b3). The outer peripheral wall of the second rotating shaft (7b) has a second annular shoulder (7b3). A second sealing ring (12b) is provided between the second rotating shaft (7b) and the inner peripheral wall of the second mounting cavity (2b3). The second mounting cavity (2b3) is connected to the return oil port (T) through the second pressure relief channel (2b4) on the second valve core (2b).

8. The dual-core directional valve according to claim 7, characterized in that:; A first ball bearing (13a) is provided between the bottom surface of the first rotating shaft (7a) and the bottom surface of the first mounting cavity (2a3); a second ball bearing (13b) is provided between the bottom surface of the second rotating shaft (7b) and the bottom surface of the second mounting cavity (2b3).

9. The dual-core directional valve according to claim 8, characterized in that: The first pressure relief channel (2a4) is equipped with a first check valve (3a). When the pressure in the first mounting chamber (2a3) is greater than the back pressure at the return port (T), the first check valve (3a) opens to release the oil pressure in the first mounting chamber (2a3) through the first pressure relief channel (2a4). The second pressure relief channel (2b4) is equipped with a third check valve (3c). When the pressure in the second mounting chamber (2b3) is greater than the back pressure at the return port (T), the third check valve (3c) opens to release the oil pressure in the second mounting chamber (2b3) through the second pressure relief channel (2b4).

10. A dual-spool directional control valve, comprising a valve body (1) and a valve spool, wherein the valve body (1) is provided with a valve spool cavity and a pressure port (P), a return port (T), a first port (A), and a second port (B) communicating with the valve spool cavity, and the valve spool is disposed within the valve spool cavity and is axially movable; characterized in that: The valve core consists of two parts: a first valve core (2a) and a second valve core (2b) coaxially arranged. The first valve core (2a) is driven by a first driving structure and can move axially, while the second valve core (2b) is driven by a second driving structure and can move axially. The first valve core (2a) and the second valve core (2b) can move axially relative to each other. The axial movement of the first valve core (2a) can connect the first oil port (A) with the pressure oil port (P) or the return oil port (T), or block the first oil port (A) from both the pressure oil port (P) and the return oil port (T). The axial movement of the second valve core (2b) can connect the second oil port (B) with the pressure oil port (P) or the return oil port (T), or block the second oil port (B) from both the pressure oil port (P) and the return oil port (T). The first driving structure includes a first control chamber located on the left side of the valve core cavity. The outer end of the first valve core (2a) has a first annular shoulder (2a2) that protrudes outward. The outer end of the first valve core (2a) extends into the first control chamber and divides the first control chamber into a first external pressure chamber (5a) and a first internal pressure chamber (5b). The axial movement of the first valve core (2a) is driven by the oil inlet and outlet of the first external pressure chamber (5a) and the first internal pressure chamber (5b). The area of ​​the pressure oil in the first external pressure chamber (5a) acting on the first valve core (2a) is greater than the sum of the area of ​​the pressure oil in the first internal pressure chamber (5b) acting on the first valve core (2a) and the area acting on the first valve core (2a) after entering the valve core cavity through the pressure oil port (P). The second drive structure includes a second control chamber located on the right side of the valve core cavity. The outer end of the second valve core (2b) has a protruding second annular shoulder (2b2). The outer end of the second valve core (2b) extends into the second control chamber and divides the second control chamber into a second external pressure chamber (5c) and a second internal pressure chamber (5d). The axial movement of the second valve core (2b) is driven by the oil inlet and outlet of the second external pressure chamber (5c) and the second internal pressure chamber (5d). The area of ​​the pressure oil in the second external pressure chamber (5c) acting on the second valve core (2b) is greater than the sum of the area of ​​the pressure oil in the second pressure chamber (1b) acting on the second valve core (2b) and the area acting on the second valve core (2b) after entering the valve core cavity through the pressure oil port (P).

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