Control valve structure, hydraulic control system, and tractor

Abstract

This invention provides a control valve structure, a hydraulic control system, and a tractor. The control valve structure includes: a main valve body; a main valve stem movably inserted within the main flow path; a bypass valve and a buffer valve spaced apart in a second branch flow path, the main flow path communicating with the second branch flow path located between the bypass valve and the buffer valve; when the main valve stem is in the blocked position, the inlet valve is closed, the bypass valve is open, and the buffer valve is closed, allowing fluid in the main flow path to return through a first return flow path; when the main valve stem is in the yielding position, the inlet valve is open, and both the bypass valve and the buffer valve are closed, allowing fluid in the main flow path to flow out through the first connecting flow path; when the main valve stem is in the buffer position, the inlet valve and the bypass valve are closed, and the buffer valve is open, allowing fluid in the main flow path to flow out through a second return flow path. The technical solution provided by this invention solves the technical problem of high impact pressure experienced by the control valve structure during position switching in the prior art.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control system technology, and more specifically, to a control valve structure, a hydraulic control system, and a tractor. Background Technology

[0002] Currently, existing technologies can control the rising and falling of hydraulic cylinders through a control valve structure. Specifically, the hydraulic cylinder rises by supplying oil into it, and falls by allowing oil to flow out. Existing technologies generally change the state of the hydraulic cylinder by altering the position of the control valve.

[0003] However, control valves in existing technologies are often subjected to significant impact forces during position switching. These impact forces act directly on the control valve itself, and over time, they can cause considerable damage to the valve's structure. Summary of the Invention

[0004] The main objective of this invention is to provide a control valve structure, a hydraulic control system, and a tractor to solve the technical problem that the control valve structure in the prior art is subjected to large impact pressure during position switching.

[0005] To achieve the above objectives, according to one aspect of the present invention, a control valve structure is provided, comprising:

[0006] The main valve body is provided with a main flow path, a first branch flow path and a second branch flow path, which are spaced apart.

[0007] The main valve stem is movably installed in the main flow path. The main valve stem has a blocking position for blocking the connection between the main flow path and the first branch flow path, a yielding position for avoiding the connection between the main flow path and the first branch flow path, and a buffer position located between the blocking position and the yielding position.

[0008] An inlet valve, a bypass valve, and a buffer valve are provided. The inlet valve is located on the first branch flow path, and the bypass valve and the buffer valve are spaced apart on the second branch flow path. The main flow path is connected to the second branch flow path located between the bypass valve and the buffer valve.

[0009] The main valve body also has a first connecting flow path, a first return flow path, and a second return flow path. The first connecting flow path is used to connect with the first branch flow path, and both the first and second return flow paths are used to connect with the second branch flow path. When the main valve stem is in the blocking position, the inlet valve is closed, the bypass valve is open, and the buffer valve is closed, so that the fluid in the main flow path flows back through the first return flow path. When the main valve stem is in the yielding position, the inlet valve is open, and both the bypass valve and the buffer valve are closed, so that the fluid in the main flow path flows out through the first connecting flow path. When the main valve stem is in the buffer position, the inlet valve and the bypass valve are closed, and the buffer valve is open, so that the fluid in the main flow path flows out through the second return flow path.

[0010] Furthermore, the second branch flow path has a first blocking port, and the valve stem of the bypass valve is movably disposed in the second branch flow path to block or avoid the first blocking port through the valve stem; when the bypass valve avoids the first blocking port, the fluid in the second branch flow path flows into the first return flow path through the first blocking port; and / or,

[0011] The second branch flow path has a second sealing port, and the valve stem of the buffer valve is movably disposed in the second branch flow path so as to block or avoid the second sealing port through the valve stem of the buffer valve; when the buffer valve avoids the second sealing port, the fluid in the second branch flow path flows into the second return flow path through the second sealing port.

[0012] Furthermore, a liquid storage tank is provided on the main valve stem, and a second connecting flow path is also provided on the main valve body. One end of the second connecting flow path is connected to the buffer chamber of the bypass valve, and the other end of the second connecting flow path is connected to the liquid storage tank.

[0013] Specifically, when the bypass valve moves to block the first sealing port, the fluid in the storage tank flows into the buffer chamber of the bypass valve through the second connecting flow path; when the bypass valve moves to avoid the first sealing port, the fluid in the buffer chamber of the bypass valve flows into the storage tank through the second connecting flow path.

[0014] Furthermore, the liquid storage tank includes:

[0015] The radial groove extends radially along the main valve stem and is connected to the other end of the second connecting flow path;

[0016] The axial groove communicates with the radial groove and extends along the axial direction of the main valve stem.

[0017] Furthermore, a third connecting flow path is also provided on the main valve body. One end of the third connecting flow path is connected to the main flow path, and the other end of the third connecting flow path is connected to the spring cavity of the buffer valve.

[0018] Specifically, when the main valve stem is in the blocking position, it blocks the connection between the third connecting flow path and the main flow path; when the main valve stem is in the yielding position, it yields to the connection between the third connecting flow path and the main flow path.

[0019] Furthermore, the main valve body is also provided with a third branch flow path and a third return branch path that are interconnected, and the third branch flow path is connected to the first connecting flow path; the control valve structure also includes:

[0020] A return valve, at least a portion of the valve stem of which is movably disposed within a third branch flow path, so as to block or prevent connection of the third branch flow path through the valve stem of the return valve.

[0021] Specifically, when the valve stem of the return valve bypasses and connects to the third branch flow path, the fluid in the first connecting flow path flows out through the third branch flow path and the third return branch; when the valve stem of the return valve blocks and isolates the third branch flow path, the first connecting flow path and the third return branch are disconnected.

[0022] Furthermore, the end of the return valve stem extends out of the third branch flow path; the control valve structure also includes:

[0023] An operating element is disposed on the main valve stem, protruding from the main valve stem. At least a portion of the operating element is disposed opposite to the valve stem of the return valve, so that the main valve stem pushes the valve stem of the return valve through the operating element.

[0024] Furthermore, at least a portion of the buffer valve extends out of the second branch flow path, and the operating element is also provided with a clearance hole, which is adapted to at least a portion of the buffer valve, and at least a portion of the buffer valve passes through the clearance hole.

[0025] According to another aspect of the present invention, a hydraulic control system is provided, comprising:

[0026] The control valve structure described above;

[0027] The hydraulic cylinder is connected to the first connecting flow path;

[0028] The oil tank, the first return flow path, and the second return flow path are all connected to the oil tank.

[0029] According to another aspect of the present invention, a tractor is provided, including the hydraulic control system described above.

[0030] By applying the technical solution of this invention, a buffer position is provided between the blocking position and the avoidance position of the main valve stem. This ensures that the main valve stem passes through the buffer position when switching from the blocking position to the avoidance position or vice versa. When the inlet valve and bypass valve are closed, the buffer valve opens, facilitating the smooth flow of fluid from the main flow path through the second return flow path. This prevents excessive pressure in the main flow path, effectively buffering the flow, reducing damage to the control valve structure, and protecting the control valve structure. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 A schematic diagram of the structure of a hydraulic control system provided according to an embodiment of the present invention is shown;

[0033] Figure 2 A schematic diagram of the hydraulic control system provided according to an embodiment of the present invention in the neutral position is shown;

[0034] Figure 3 A schematic diagram of the structure of the hydraulic control system provided according to an embodiment of the present invention in the rising state is shown;

[0035] Figure 4 A schematic diagram of the structure of the hydraulic control system provided according to an embodiment of the present invention in a buffer state is shown;

[0036] Figure 5 A schematic diagram of the hydraulic control system provided according to an embodiment of the present invention in the descent state is shown.

[0037] The above figures include the following reference numerals:

[0038] 10. Control valve structure; 11. Main valve body; 111. Main flow path; 112. First branch flow path; 113. Second branch flow path; 114. First connecting flow path; 115. First return flow path; 116. Second return flow path; 117. Third connecting flow path; 118. Third branch flow path; 119. Third return branch path; 12. Main valve stem; 121. Liquid reservoir; 1211. Radial groove; 1212. Axial groove; 13. Inlet valve; 14. Bypass valve; 15. Buffer valve; 16. Return valve; 17. Operating components;

[0039] 20. Hydraulic cylinder; 30. Oil tank; 40. Oil suction filter; 50. Oil pump; 60. Safety valve. Detailed Implementation

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] like Figures 1 to 5 As shown, Embodiment 1 of the present invention provides a control valve structure 10, which includes a main valve body 11, a main valve stem 12, an inlet valve 13, a bypass valve 14, and a buffer valve 15. The main valve body 11 is provided with a main flow path 111, a first branch flow path 112, and a second branch flow path 113, which are spaced apart. The main valve stem 12 is movably inserted into the main flow path 111 and has a blocking position for blocking the connection between the main flow path 111 and the first branch flow path 112, a bypass position for avoiding the connection between the main flow path 111 and the first branch flow path 112, and a buffer position located between the blocking position and the bypass position. The inlet valve 13 is disposed on the first branch flow path 112, and the bypass valve 14 and the buffer valve 15 are spaced apart on the second branch flow path 113. The main flow path 111 is connected to the second branch flow path 113 located between the bypass valve 14 and the buffer valve 15. The main valve body 11 also has a first connecting flow path 114, a first return flow path 115, and a second return flow path 116. The first connecting flow path 114 is used to connect with the first branch flow path 112, and the first return flow path 115 and the second return flow path 116 are both used to connect with the second branch flow path 113. When the main valve stem 12 is in the blocking position, the inlet valve 13 is closed, the bypass valve 14 is open, and the buffer valve 15 is closed, so that the fluid in the main flow path 111 flows back through the first return flow path 115. When the main valve stem 12 is in the yielding position, the inlet valve 13 is open, and the bypass valve 14 and the buffer valve 15 are both closed, so that the fluid in the main flow path 111 flows out through the first connecting flow path 114. When the main valve stem 12 is in the buffer position, the inlet valve 13 and the bypass valve 14 are closed, and the buffer valve 15 is open, so that the fluid in the main flow path 111 flows out through the second return flow path 116.

[0042] The control valve structure 10 provided in this embodiment has a buffer position between the blocking position and the avoidance position of the main valve stem 12. When the main valve stem 12 switches from the blocking position to the avoidance position or vice versa, the main valve stem 12 will pass through the buffer position. Thus, when the inlet valve 13 and the bypass valve 14 are closed, the buffer valve 15 opens, which facilitates the smooth flow of fluid in the main flow path 111 through the second return flow path 116, thereby avoiding excessive pressure in the main flow path 111. This effectively buffers the flow, reduces damage to the control valve structure 10, and facilitates the protection of the control valve structure 10.

[0043] Specifically, the inlet valve 13 can be a one-way valve. Specifically, in this embodiment, the main valve body 11 is provided with an oil inlet, which is located above the first branch flow path 112, and the main flow path 111 is located below the first branch flow path 112. The connection method between the oil inlet and the main flow path is as follows: Figure 1 As shown by the dashed line passing through the first branch flow path 112, it can also be understood that the oil inlet and the main flow path are directly connected through the connecting channel on the main valve body 11. One end of the connecting channel is connected to the oil inlet, and the other end of the connecting channel is connected to the main flow path. This connecting channel avoids the first branch flow path 112, that is, the connecting channel is not connected to the first branch flow path 112.

[0044] In this embodiment, the second branch flow path 113 has a first blocking port, and the valve stem of the bypass valve 14 is movably disposed on the second branch flow path 113 to block or bypass the first blocking port through the valve stem of the bypass valve 14. When the bypass valve 14 bypasses the first blocking port, the fluid in the second branch flow path 113 flows into the first return flow path 115 through the first blocking port. This structural arrangement is simple, easy to operate, and facilitates the smooth blocking or bypassing of the first blocking port to open or close the bypass valve 14.

[0045] Specifically, in this embodiment, the second branch flow path 113 has a second blocking port, and the valve stem of the buffer valve 15 is movably disposed on the second branch flow path 113 to block or avoid the second blocking port through the valve stem of the buffer valve 15; when the buffer valve 15 avoids the second blocking port, the fluid in the second branch flow path 113 flows into the second return flow path 116 through the second blocking port. This structural arrangement is simple, easy to operate, and facilitates the smooth blocking or avoidance of the first blocking port to open or close the buffer valve 15.

[0046] In this embodiment, a liquid storage tank 121 is provided on the main valve stem 12, and a second connecting flow path is also provided on the main valve body 11. One end of the second connecting flow path is connected to the buffer chamber of the bypass valve 14, and the other end of the second connecting flow path is connected to the liquid storage tank 121. When the bypass valve 14 moves to block the first sealing port, the fluid in the liquid storage tank 121 flows into the buffer chamber of the bypass valve 14 through the second connecting flow path; when the bypass valve 14 moves to avoid the first sealing port, the fluid in the buffer chamber of the bypass valve 14 flows into the liquid storage tank 121 through the second connecting flow path. This structural arrangement facilitates changing the flow direction of the fluid in the liquid storage tank 121 and the buffer chamber according to specific circumstances, thereby facilitating the opening or closing of the bypass valve 14.

[0047] Specifically, the liquid storage tank 121 includes a radial groove 1211 and an axial groove 1212. The radial groove 1211 extends radially along the main valve stem 12 and is connected to the other end of the second connecting flow path. The axial groove 1212 is connected to the radial groove 1211 and extends axially along the main valve stem 12. This structural arrangement facilitates increasing the volume of the liquid storage tank 121, allowing it to better accommodate more fluid, thereby facilitating the switching of the bypass valve 14.

[0048] Specifically, there can be multiple radial grooves 1211, which are spaced apart along the extension direction of the axial groove 1212, and all of the radial grooves 1211 are connected to the axial groove 1212.

[0049] In this embodiment, the main valve body 11 is further provided with a third connecting flow path 117. One end of the third connecting flow path 117 is connected to the main flow path 111, and the other end of the third connecting flow path 117 is connected to the spring cavity of the buffer valve 15. Specifically, when the main valve stem 12 is in the blocking position, it blocks the connection between the third connecting flow path 117 and the main flow path 111; when the main valve stem 12 is in the yielding position, it yields to the connection between the third connecting flow path 117 and the main flow path 111. This structural arrangement is simple, easy to operate, and facilitates the smooth blocking or yielding of the connection between the third connecting flow path 117 and the main flow path 111 by the main valve stem 12, thereby facilitating smooth buffering and pressure reduction.

[0050] Specifically, the main valve body 11 is also provided with a third branch flow path 118 and a third return flow path 119 that are interconnected. The third branch flow path 118 is connected to the first connecting flow path 114. The control valve structure 10 also includes a return valve 16, at least a portion of which is movably disposed within the third branch flow path 118 to block or prevent connection of the third branch flow path 118 via the valve stem. Specifically, when the valve stem of the return valve 16 prevents connection of the third branch flow path 118, the fluid in the first connecting flow path 114 flows out through the third branch flow path 118 and then through the third return flow path 119; when the valve stem of the return valve 16 blocks the third branch flow path 118, the first connecting flow path 114 is disconnected from the third return flow path 119. This structural arrangement facilitates stable oil return through the return valve 16.

[0051] Specifically, the return valve 16 can be a one-way valve. Specifically, the connection method between the third branch flow path 118 and the first connecting flow path 114 is as follows: Figure 1As shown by the dashed line between the third branch flow path 118 and the first connecting flow path 114, the third branch flow path 118 and the first connecting flow path 114 are directly connected through a connecting channel on the main valve body 11. One end of the connecting channel is connected to the third branch flow path 118, and the other end of the connecting channel is connected to the first connecting flow path 114. This connecting channel avoids the main flow path 111 and the second branch flow path 113, that is, this connecting channel is not connected to the main flow path 111 and the second branch flow path 113.

[0052] In this embodiment, the end of the valve stem of the return valve 16 extends out of the third branch flow path 118. The control valve structure 10 also includes an operating member 17, which is disposed on the main valve stem 12 and protrudes from the main valve stem 12. At least a portion of the operating member 17 is disposed opposite to the valve stem of the return valve 16, so that the main valve stem 12 pushes the valve stem of the return valve 16 to move through the operating member 17. Specifically, the operating member 17 is fixedly connected to the main valve stem 12 so as to push the valve stem of the return valve 16 to move during the operation of the main valve stem 12, thereby opening the return valve 16.

[0053] Specifically, the operating component 17 includes an operating plate and an operating lever connected to each other. The operating plate is fixedly connected to the main valve stem 12, and the operating lever is fixedly connected to the operating plate. The operating lever is arranged opposite to the valve stem of the return oil valve 16 so that the operating lever moves during the movement of the main valve stem 12, and pushes the return oil valve 16 to move so that the return oil valve 16 opens.

[0054] Specifically, at least a portion of the buffer valve 15 extends out of the second branch flow path 113, and the operating member 17 is also provided with a clearance hole that is adapted to at least a portion of the buffer valve 15, with at least a portion of the buffer valve 15 passing through the clearance hole. This structural arrangement prevents the force exerted by the operating member 17 on the buffer valve 15, thus avoiding damage to the buffer valve 15 due to excessive force.

[0055] Embodiment 2 of the present invention provides a hydraulic control system, including: the control valve structure 10, the cylinder 20, and the oil tank 30 provided in Embodiment 1 above. The cylinder 20 is connected to the first connecting flow path 114; the first return flow path 115 and the second return flow path 116 are both connected to the oil tank 30. This structural arrangement facilitates the return of fluid from the first return flow path 115 and the second return flow path 116 to the oil tank 30. Furthermore, the main valve body 11 is also provided with an oil inlet connected to the main flow path 111, which is also connected to the oil tank 30, so that the oil in the oil tank 30 can smoothly enter the main flow path 111 through the oil inlet.

[0056] The hydraulic control system in this embodiment also includes an oil suction filter 40, an oil pump 50, and a safety valve 60. The oil suction filter 40 filters impurities in the oil, the oil pump 50 provides sufficient power for oil circulation, and the safety valve 60 ensures that the oil in the entire hydraulic control system is controlled within a safe hydraulic range.

[0057] Specifically, the hydraulic control system in this embodiment has a neutral state, an ascending state, a buffer state, and a descending state.

[0058] Among them, such as Figure 2 As shown, when the hydraulic control system is in the neutral position: the oil pump 50 delivers the oil in the oil tank 30 through the suction filter 40 to the P port (i.e., the oil inlet) of the multi-way valve. At this time, the main valve stem 12 is in the neutral position, the pressure oil opens the bypass valve 14, and the oil flows back to the oil tank 30 through the T1 port of the first return flow path 115.

[0059] like Figure 3 As shown, when the hydraulic control system is in the rising state: when the main valve stem 12 moves to the right, the pressurized oil reaches the spring chamber of the bypass valve 14 through the main valve stem 12. At this time, the bypass valve 14 is closed under the action of the spring force. Simultaneously, the pressurized oil reaches the spring chamber of the buffer valve 15, which is also closed under the action of the spring force. After passing through the main valve stem 12, the pressurized oil also reaches the inlet valve 13. After opening the inlet valve 13, the pressurized oil enters the cylinder 20, realizing the rising of the cylinder 20. Specifically, Figure 3 The arrow located to the right of the operating element 17 indicates the direction of movement of the operating element 17.

[0060] like Figure 4 As shown, when the hydraulic control system is in a buffer state: when the main valve stem 12 moves to the left and is almost at the neutral position, the bypass valve 14 is closed and the return valve 16 is not open. Because the main valve stem 12 is near the neutral position, the pressure oil gradually decreases through the throttling grooves (corresponding to radial grooves 1211 and axial grooves 1212) of the main valve stem 12, and then the pressure after passing through the throttling orifice also gradually decreases. At this time, the pressure acting on the buffer valve 15 gradually increases, and the pressure oil returns to the oil tank 30 after opening the buffer valve 15. In this way, during the process of the main valve stem 12 returning to the neutral position, the working pressure gradually decreases, thereby avoiding large impacts. Specifically, the throttling orifice is located between the main flow path 111 and the spring chamber of the buffer valve 15, so that the reservoir 121 on the main valve stem 12 is connected or disconnected from the spring chamber of the buffer valve 15 through the throttling orifice. Figure 4 The arrow located to the right of the operating element 17 indicates the direction of movement of the operating element 17.

[0061] like Figure 5As shown, when the hydraulic control system is in the descending state: when the main valve stem 12 moves to the left, the pressurized oil reaches the bypass valve 14 through the main valve stem 12; at this time, the spring chamber of the bypass valve 14 returns oil through the main valve stem 12, and the pressurized oil can open the bypass valve 14, and then return oil to the oil tank 30 through port T1. When the main valve stem 12 moves to the left, the main valve stem 12 drives the operating element 17 to move simultaneously, pushing the return oil valve 16 to move to the left against the spring force, thereby opening the return oil valve 16. Under the action of the load, the oil in the large chamber of the cylinder 20 returns directly to the oil tank 30 through the return oil valve 16, thereby realizing the descent. Specifically, the operating element 17 can be a pull rod, and the return oil valve 16 can also be called a descending valve. Figure 5 The two arrows located to the right of the operating element 17 represent the movement direction of the operating element 17 and the movement direction of the valve stem of the return valve 16, respectively.

[0062] Embodiment 3 of the present invention provides a tractor including the hydraulic control system provided in Embodiment 2 above. Specifically, this hydraulic control system is applicable to the rear suspension device of a low-horsepower tractor.

[0063] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: compact structure, high reliability, effective buffering, and reduction of the impact force on the control valve structure 10.

[0064] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0065] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0066] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0067] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0068] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control valve structure, characterized in that, include: The main valve body (11) is provided with a main flow path (111), a first branch flow path (112) and a second branch flow path (113), and the first branch flow path (112) and the second branch flow path (113) are arranged at intervals; The main valve stem (12) is movably inserted into the main flow path (111). The main valve stem (12) has a blocking position for blocking the connection between the main flow path (111) and the first branch flow path (112), a yielding position for avoiding the connection between the main flow path (111) and the first branch flow path (112), and a buffer position located between the blocking position and the yielding position. An inlet valve (13), a bypass valve (14), and a buffer valve (15) are provided. The inlet valve (13) is disposed on the first branch flow path (112). The bypass valve (14) and the buffer valve (15) are disposed at intervals on the second branch flow path (113). The main flow path (111) is connected to the second branch flow path (113) located between the bypass valve (14) and the buffer valve (15). The main valve body (11) further comprises a first connecting flow path (114), a first return flow path (115), and a second return flow path (116). The first connecting flow path (114) is used to connect with the first branch flow path (112), and both the first return flow path (115) and the second return flow path (116) are used to connect with the second branch flow path (113). When the main valve stem (12) is in the blocked position, the inlet valve (13) is closed, the bypass valve (14) is opened, and the buffer valve (15) is closed, so that the main flow path (111) is closed. The fluid in the main flow path (111) flows back through the first return flow path (115); when the main valve stem (12) is in the avoidance position, the inlet valve (13) is open, the bypass valve (14) and the buffer valve (15) are both closed, so that the fluid in the main flow path (111) flows out through the first connecting flow path (114); when the main valve stem (12) is in the buffer position, the inlet valve (13) and the bypass valve (14) are closed, and the buffer valve (15) is open, so that the fluid in the main flow path (111) flows out through the second return flow path (116).

2. The control valve structure according to claim 1, characterized in that, The second branch flow path (113) has a first blocking port, and the valve stem of the bypass valve (14) is movably disposed on the second branch flow path (113) to block or bypass the first blocking port through the valve stem of the bypass valve (14); when the bypass valve (14) bypasses the first blocking port, the fluid in the second branch flow path (113) flows into the first return flow path (115) through the first blocking port; and / or, The second branch flow path (113) has a second blocking port. The valve stem of the buffer valve (15) is movably disposed on the second branch flow path (113) so as to block or avoid the second blocking port through the valve stem of the buffer valve (15). When the buffer valve (15) avoids the second blocking port, the fluid in the second branch flow path (113) flows into the second return flow path (116) through the second blocking port.

3. The control valve structure according to claim 2, characterized in that, The main valve stem (12) is provided with a liquid storage tank (121), and the main valve body (11) is also provided with a second connecting flow path. One end of the second connecting flow path is connected to the buffer chamber of the bypass valve (14), and the other end of the second connecting flow path is connected to the liquid storage tank (121). When the bypass valve (14) moves to block the first sealing port, the fluid in the storage tank (121) flows into the buffer chamber of the bypass valve (14) through the second connecting flow path; when the bypass valve (14) moves to avoid the first sealing port, the fluid in the buffer chamber of the bypass valve (14) flows into the storage tank (121) through the second connecting flow path.

4. The control valve structure according to claim 3, characterized in that, The liquid storage tank (121) includes: A radial groove (1211) extends radially along the main valve stem (12) and is connected to the other end of the second connecting flow path; An axial groove (1212) is connected to the radial groove (1211), and the axial groove (1212) extends axially along the main valve stem (12).

5. The control valve structure according to claim 2, characterized in that, The main valve body (11) is also provided with a third connecting flow path (117), one end of the third connecting flow path (117) is connected to the main flow path (111), and the other end of the third connecting flow path (117) is connected to the spring cavity of the buffer valve (15). When the main valve stem (12) is in the blocking position, the main valve stem (12) blocks the connection between the third connecting flow path (117) and the main flow path (111); when the main valve stem (12) is in the avoidance position, the main valve stem (12) avoids the connection between the third connecting flow path (117) and the main flow path (111).

6. The control valve structure according to claim 1, characterized in that, The main valve body (11) is also provided with a third branch flow path (118) and a third return branch path (119) that are interconnected. The third branch flow path (118) is connected to the first connecting flow path (114). The control valve structure also includes: A return valve (16) has at least a portion of its stem movably disposed within the third branch flow path (118) to block or prevent connection of the third branch flow path (118) through the stem of the return valve (16). When the valve stem of the return valve (16) bypasses and connects to the third branch flow path (118), the fluid in the first connecting flow path (114) flows out through the third branch flow path (118) and then through the third return branch (119); when the valve stem of the return valve (16) blocks and isolates the third branch flow path (118), the first connecting flow path (114) is disconnected from the third return branch (119).

7. The control valve structure according to claim 6, characterized in that, The end of the valve stem of the return valve (16) extends out of the third branch flow path (118); the control valve structure also includes: An operating element (17) is disposed on the main valve stem (12). The operating element (17) protrudes from the main valve stem (12). At least a portion of the operating element (17) is disposed opposite to the valve stem of the return valve (16) so that the main valve stem (12) pushes the valve stem of the return valve (16) to move through the operating element (17).

8. The control valve structure according to claim 7, characterized in that, At least a portion of the buffer valve (15) extends out of the second branch flow path (113), and the operating member (17) is also provided with a clearance hole, which is adapted to at least a portion of the buffer valve (15), and at least a portion of the buffer valve (15) passes through the clearance hole.

9. A hydraulic control system, characterized in that, include: The control valve structure according to any one of claims 1 to 8; The hydraulic cylinder (20) is connected to the first connecting flow path (114); The oil tank (30) is connected to the first return flow path (115) and the second return flow path (116).

10. A tractor, characterized in that, Includes the hydraulic control system described in claim 9.

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