Control valve and hydraulic system

Abstract

The utility model relates to a hydraulic technology field, concretely relates to a control valve and hydraulic system. A control valve, include: valve body, inside form have pressure oil channel, oil return oil channel and two work oil channels, two work oil channels are respectively first work oil channel and second work oil channel, valve core, assemble in valve body, sliding switch work position, valve core can be located ascending position, middle position and strong pressure descending position, still have small floating position between middle position and strong pressure descending position, when valve core is in small floating position, two work oil channels throttle communication with oil return oil channel, valve core can continue to move to big floating position after strong pressure descending position, control two work oil channels and oil return oil channel full -flow communication. The utility model further provides a kind of hydraulic system, including control valve. The technical problem that the tool is damaged when falling to the ground in the process of descending under its own weight after being lifted in prior art is solved.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic technology, specifically to a control valve and a hydraulic system. Background Technology

[0002] In existing technology, the main valve controls the tractor, and the valve core function is divided into four positions: rising, intermediate, high-pressure falling, and floating. For example... Figure 1 As shown, the hydraulic pump output oil is connected to port P' of the multi-way valve. The actuator controls the reversal of the valve core. When the valve core reverses from the neutral position to the rising position (left position in the diagram), oil is output from port A' of the main valve and enters the large chamber of the lifting cylinder. The lifting cylinder rises, and the small chamber of the lifting cylinder returns oil through port B' and the valve core to port T' of the multi-way valve, returning oil to the oil tank. When the valve core reverses to the high-pressure descending position (right position in the diagram), oil is output from port B' of the main valve and enters the small chamber of the lifting cylinder. The lifting cylinder descends, and the large chamber of the lifting cylinder returns oil through port A' and the valve core to port T' of the multi-way valve, returning oil to the oil tank. When the valve core reverses to the floating position (second position from the right in the diagram), the large and small chambers of the cylinder are connected to port T' of the main valve via the valve core, and are connected to the oil tank.

[0003] On tractors, the lifting mechanism typically connects to different attachments for operation. In continuous operation in the floating position, the lifting cylinder's large and small chambers are connected to the oil tank, allowing for flexible oil return and replenishment. Therefore, the attachments can adjust their height according to the terrain, and can continue working even when encountering obstacles. In actual operation, after the operator lifts the attachment and moves it to the starting position, they need to lower it. This involves directly switching the valve core to the floating position. As the valve core moves from the neutral position to the high-pressure descent position and then to the floating position, the large chamber oil return area on the main valve core continuously increases. The size of the large chamber oil return area in the floating position is increased from that in the high-pressure descent position, already starting with a large return area. The attachment's weight causes it to descend very quickly under its own weight, easily causing damage upon landing. Utility Model Content

[0004] To address the technical problem in existing technologies where the attachment descends rapidly under its own weight after being lifted, easily causing damage to the attachment upon landing, this invention provides a control valve and hydraulic system that solves the aforementioned technical problem.

[0005] The technical solution of this utility model is as follows: This utility model provides a control valve, comprising: The valve body has a pressure oil passage, a return oil passage and two working oil passages inside, which are the first working oil passage and the second working oil passage. The valve core, assembled in the valve body, slides to switch positions. The valve core can be located in the rising position, the intermediate position, and the high-pressure drop position. There is also a small floating position between the intermediate position and the high-pressure drop position. When the valve core is in the small floating position, the two working oil passages are throttled and connected to the return oil passage. After passing the high-pressure drop position, the valve core can continue to move to the large floating position, controlling the two working oil passages to be fully connected to the return oil passage.

[0006] According to one embodiment of the present invention, an unloading oil passage is also formed in the valve body. When the valve core is in the middle position, the small floating position, and the large floating position, the pressure oil in the pressure oil passage is unloaded through the unloading oil passage.

[0007] According to one embodiment of the present invention, when the valve core is in the strong pressure drop position, the pressure oil introduced into the pressure oil passage is throttled and unloaded.

[0008] According to one embodiment of the present invention, when the valve core is in the high pressure drop position, the second working oil passage connected to the pressure oil passage is throttled and connected to the return oil passage; or, the pressure oil passage is throttled and connected to the unloading oil passage.

[0009] According to one embodiment of the present invention, two working oil passages are arranged on both sides of the pressure oil passage, and the return oil passage extends to both sides of the two working oil passages. The pressure oil passage introduces pressure oil to oil port P1 and oil port P2. The unloading oil passage extends to the outer periphery of the valve core to form oil port C. There are two oil ports P1, which are located on both sides of oil port C respectively. Oil port P2 is located between the second working oil passage and the adjacent oil port P1.

[0010] According to one embodiment of the present invention, a first flow passage structure is formed on the valve core to control the connection between the oil port P1, the first working oil passage and the return oil passage; when the valve core is in a small floating position, the first working oil passage is connected to the first flow passage structure, and the first flow passage structure is throttled connected to the return oil passage.

[0011] According to one embodiment of the present invention, a second flow-through structure is formed on the valve core to control the connection between oil port P1 and oil port C. The second flow-through structure includes a first flow-through groove, a second flow-through groove, and a third flow-through groove arranged axially. A third flow-through structure is formed on the valve core to control the connection between oil port P2, the second working oil passage, and the return oil passage. The third flow-through structure includes a fourth flow-through groove, a fifth flow-through groove, and a sixth flow-through groove arranged axially.

[0012] According to one embodiment of the present invention, when the pressure drops, the second working oil passage is throttled and connected to the fifth flow channel, and the fifth flow channel is fully connected to the return oil passage; or, the oil port P1 is throttled and connected to the second flow channel, and the second flow channel is fully connected to the oil port C.

[0013] According to one embodiment of the present invention, a connecting oil passage is also formed in the valve body, and the second working oil passage is connected to the return oil passage through the connecting oil passage. A single-acting or double-acting switching valve is provided on the connecting oil passage.

[0014] This utility model also provides a hydraulic system, including: Pump; Control valve, wherein the pump outlet is connected to the pressure oil passage; The actuator has a rod-side chamber and a rodless chamber, the rodless chamber being connected to a first working oil passage and the rod-side chamber being connected to a second working oil passage.

[0015] Based on the above technical solution, the technical effects that this utility model can achieve are as follows: This utility model's control valve features a small floating position between the neutral and high-pressure descent positions. After the attachment is lifted, the valve core can move from the neutral position to the small floating position, where the two working oil passages are throttled and connected to the return oil passage. The actuator can float freely, returning oil to the oil tank or receiving oil from the tank. Due to the influence of the valve core's oil passage opening area, throttling is created through the small opening area, thus generating back pressure. Under the action of back pressure, as the attachment is lifted into the air and the valve core moves to the small floating position and descends under its own weight, the descent speed is limited, protecting the attachment from damage due to a rapid fall to the ground. After the valve core reaches the large floating position from the high-pressure descent position, the two working oil passages are fully connected to the return oil passage, providing a large connection area. This is suitable for complex working environments with large undulations or many obstructions, allowing the actuator to perform large-range vertical floating operations. The control valve of this utility model has an unloading oil passage in the valve body. When it is in the middle position, small floating position and large floating position, the pressure oil in the pressure oil passage can flow out of the valve body through the unloading oil passage to avoid the pressure oil impacting the valve core. The control valve of this invention, when the valve core is in the high-pressure drop position, throttles and unloads the pressure oil introduced into the pressure oil passage, allowing the actuator to drive the attachment to press to the target depth below the ground without causing the vehicle to stall. Specifically, the throttling and unloading of the pressure oil can be achieved by either throttling and connecting the second working oil passage (which is connected to the pressure oil passage) to the return oil passage, or by directly throttling and connecting the pressure oil passage to the unloading oil passage. The control valve of this utility model ensures the connection between the control oil passages of the valve core in different working positions by rationally arranging the pressure oil passage, working oil passage, return oil passage and unloading oil passage in the valve body, as well as setting the flow passage structure on the valve core. The control valve of this utility model, by setting a connecting oil passage and a single / double-acting switching valve, can realize single / double-acting switching. When the single / double-acting switching valve is closed, the pressure oil enters the rod chamber of the actuator through the second working oil passage, and the rodless chamber of the actuator returns oil through the first working oil passage, realizing double-acting descent. When the single / double-acting switching valve is open, the second working oil passage and the return oil passage are connected. After the pressure oil reaches the second working oil passage, it returns oil through the connecting oil passage, and only the rodless chamber of the actuator returns oil, realizing single-acting descent. The holding valve functions to reduce leakage in the rodless chamber of the actuator in the neutral position and reduce the static settling of the actuator. It is opened by oil during lifting action and mechanically opened by the valve core during descent action. The hydraulic system of this invention uses the aforementioned control valve to control the actuator's operation. By setting a small floating position, the speed at which the attachment descends under its own weight can be controlled by adjusting the valve core displacement and the size of the valve core's return oil area, thus controlling the speed of descent and preventing rapid falling through back pressure. Normal operation can be performed in the small floating position, and in working environments requiring a larger return oil area, the system can be switched to a large floating position to solve the problem of rapid falling of the attachment in the floating position. By introducing pressure oil through a pressure oil passage in the high-pressure descent position for throttling and unloading, the upper limit of the pressure in the actuator's rod chamber is limited. Before the pressure in the rod chamber reaches the load pressure sufficient to support the vehicle, the oil will be throttled back to the oil tank through a bypass, preventing the vehicle from being supported. Attached Figure Description

[0016] Figure 1 This is a hydraulic schematic diagram of the main valve controlling the operation of tractor attachments in the prior art; Figure 2 This is a schematic diagram of the control valve core in the neutral position according to Embodiment 1 of this utility model. Figure 3 A schematic diagram of the control valve when the valve core is in the raised position; Figure 4 A schematic diagram of the structure of the control valve when the valve core is in a small floating position; Figure 5 A schematic diagram of the structure of the control valve when the valve core is in the high-pressure drop position; Figure 6 A schematic diagram of the structure of the control valve when the valve core is in a large floating position; Figure 7 This is a schematic diagram of the valve core of a control valve. Figure 8 Hydraulic schematic diagram of the control valve; Figure 9 This is a hydraulic schematic diagram of a hydraulic system. Figure 10 This is a schematic diagram of the control valve core in the high-pressure drop position according to Embodiment 2 of this utility model; Figure 11 Hydraulic schematic diagram of the control valve; In the diagram: 1-Valve body; 11-Pressure oil passage; 12-Return oil passage; 13-First working oil passage; 14-Second working oil passage; 15-Connecting oil passage; 2-Valve core; 21-First flow passage structure; 211-First annular groove; 212-Second annular groove; 213-Transition section; 22-Second flow passage structure; 221-First flow groove; 222-Second flow groove; 223-Third flow groove; 23-Third flow passage structure; 231-Fourth flow groove; 232-Fifth flow groove; 233-Sixth flow groove; 3-Single / double-acting switching valve; 4-Holding valve; 5-Check valve; 6-Drive assembly; 7-Pump; 8-Actuator; 9-Oil tank. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0018] 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.

[0019] 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 invention. 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.

[0020] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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 utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0021] 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.

[0022] 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 utility model.

[0023] Example 1

[0024] like Figure 2-9 As shown, this embodiment provides a control valve for controlling the action of actuator 8. The control valve includes a valve body 1 and a valve core 2. Multiple oil passages are formed within the valve body 1. The valve core 2 is assembled within the valve body 1. The sliding switching position allows control of the on / off state between different oil passages when the valve core 2 is in different positions. The valve core 2 can be located in an ascending position, a neutral position, and a high-pressure descending position. A small floating position is provided between the neutral position and the high-pressure descending position. After passing the high-pressure descending position, the valve core 2 can continue to move to the large floating position.

[0025] like Figure 2-6As shown, a mounting hole is formed inside the valve body 1 for assembling the valve core 2. The valve body 1 also contains a pressure oil passage 11, a return oil passage 12, and a working oil passage. The pressure oil passage 11 is used to introduce pressure oil, the return oil passage 12 is connected to the oil tank 9, and there are two working oil passages: a first working oil passage 13 and a second working oil passage 14. Figure 2 , 8 As shown, when valve core 2 is in the neutral position, the pressure oil passage 11, the return oil passage 12, and the working oil passage are not connected; Figure 3 , 8 As shown, when valve core 2 is in the raised position, pressure oil passage 11 is connected to the first working oil passage 13, and the second working oil passage 14 is connected to the return oil passage 12, that is, oil enters through the first working oil passage 13 and returns through the second working oil passage 14; Figure 5 , 8 As shown, when valve core 2 is in the high-pressure drop position, pressure oil passage 11 is connected to the second working oil passage 14, and the first working oil passage 13 is connected to the return oil passage 12, that is, oil enters through the second working oil passage 14 and returns through the first working oil passage 13; Figure 4 , 8 As shown, when the valve core 2 is in the small floating position, both the first working oil passage 13 and the second working oil passage 14 are throttledly connected to the return oil passage 12; as Figure 6 , 8 As shown, when the valve core 2 is in the large floating position, the first working oil passage 13 and the second working oil passage 14 are both fully connected to the return oil passage 12.

[0026] As a preferred technical solution in this embodiment, when the valve core 2 is in the high-pressure drop position, the pressure oil introduced into the pressure oil passage 11 is throttled and unloaded to avoid the phenomenon of the vehicle stalling. Specifically, as Figure 5 , 8 As shown, when the valve core 2 is in the high pressure drop position, the second working oil passage 14 is throttled and connected to the return oil passage 12. In this way, the pressure oil in the pressure oil passage 11 enters the second working oil passage 14 and can be partially unloaded through the return oil passage 12.

[0027] As a preferred technical solution of this embodiment, the first working oil passage 13 and the second working oil passage 14 are located on both sides of the pressure oil passage 11. The first working oil passage 13 extends to the outer surface of the valve body 1 to form an oil port A1, and the second working oil passage 14 extends to the outer surface of the valve body 1 to form an oil port B1. The two ends of the return oil passage 12 extend to both sides of the two working oil passages, and the return oil passage 12 is connected to the oil tank 9.

[0028] As a preferred technical solution in this embodiment, such as Figure 2-6As shown, the valve body 1 is also provided with an unloading oil passage, which extends to the outer periphery of the valve core 2 to form an oil port C, which is connected to the mounting hole. When the valve core 2 is in the neutral position, the small floating position, and the large floating position, the pressure oil passage 11 is connected to the unloading oil passage, and the pressure oil can be unloaded through the unloading oil passage.

[0029] As a preferred technical solution in this embodiment, such as Figure 2-6 As shown, the pressure oil passage 11 is located between the two working oil passages. The pressure oil passage 11 introduces pressure oil to oil port P1 and oil port P2. There are two oil ports P1, which are connected. The two oil ports P1 are located on both sides of oil port C. Oil port P2 is located close to the second working oil passage 14. Oil port P2 is located between the second working oil passage 14 and the adjacent oil port P1.

[0030] As a preferred technical solution in this embodiment, such as Figure 2-6 As shown, a one-way valve 5 is installed on the oil line from the pressure oil passage 11 to the oil port P2 to control the one-way flow of the pressure oil.

[0031] As a preferred technical solution in this embodiment, such as Figure 2-6 As shown, a holding valve 4 is provided on the first working oil passage 13. The holding valve 4 can be selected, but is not limited to, a mechanical holding valve. The first working oil passage 13 is generally used to communicate with the rodless chamber of the actuator 8. The holding valve 4 can reduce the oil leakage of the rodless chamber when the valve core 2 is in the neutral position and reduce the static settling of the actuator 8. During the lifting action, the pressure oil can open the holding valve 4 and the pressure oil enters the actuator 8 through the first working oil passage 13. During the lowering action, the valve core 2 is linked to the mechanical opening of the holding valve 4, so that the oil in the actuator 8 can return to the return oil passage 12 through the first working oil passage 13.

[0032] As a preferred technical solution in this embodiment, such as Figure 2-6 As shown, the valve body 1 also includes a connecting oil passage 15, which connects the second working oil passage 14 and the return oil passage 12. A single-acting / double-acting switching valve 3 is installed on the connecting oil passage 15 to switch the actuator 8 between single-acting and double-acting modes. Specifically, the single-acting / double-acting switching valve 3 controls the opening and closing of the connecting oil passage 15 to achieve single-acting / double-acting switching. When the single-acting / double-acting switching valve 3 controls the connecting oil passage 15 to close, the second working oil passage 14 and the return oil passage 12 are not connected, oil enters the rod chamber of the actuator 8, and oil returns to the rodless chamber, achieving double-acting descent. When the single-acting / double-acting switching valve 3 controls the connecting oil passage 15 to open, the second working oil passage 14 and the return oil passage 12 are connected, and the pressure oil in the second working oil passage 14 returns directly through the return oil passage 12 without entering the rod chamber, and oil returns to the rodless chamber, achieving single-acting descent. Preferably, the single-acting / double-acting switching valve 3 can be configured as a manual valve, allowing manual operation to control the oil circuit opening and closing.

[0033] like Figure 2-7As shown, valve core 2 is assembled inside valve body 1. Valve core 2 is provided with a flow-through structure to facilitate the control of the flow between oil passages. Specifically, valve core 2 is provided with a first flow-through structure 21 to control the connection between oil port P1, the first working oil passage 13, and the return oil passage 12; valve core 2 is provided with a second flow-through structure 22 to control the connection between oil port P1 and oil port C; and valve core 2 is provided with a third flow-through structure 23 to control the connection between oil port P2, the second working oil passage 14, and the return oil passage 12. The relative position between the flow-through structure and the oil passage / port controls the flow area.

[0034] Specifically, the first flow passage 21 is a flow groove structure. When the valve core 2 slides, the first working oil passage 13 is connected to the pressure oil passage 11 or the return oil passage 12 through the first flow passage 21.

[0035] As a preferred embodiment, the first flow passage structure 21 includes a first annular groove 211 and a second annular groove 212. The first annular groove 211 and the second annular groove 212 are connected by a transition section 213. The transition section 213 has a tapered surface. When the valve core 2 mechanically opens the holding valve 4, the valve core 2 moves, and the transition section 213 can mechanically push the holding valve 4 open via the push rod, thus facilitating the return of oil from the actuator 8 through the first working oil passage 13. Preferably, the inner diameter of the first annular groove 211 is smaller than the inner diameter of the second annular groove 212. In the neutral position, the transition section 213 is located between the push rod and the oil port P1.

[0036] As a preferred technical solution of this embodiment, a throttling groove is formed on the shoulder of the first annular groove 211 away from the second annular groove 212. When the position is small, the first working oil passage 13 can be throttled and connected to the return oil passage 12 through the throttling groove.

[0037] Specifically, the second flow-through structure 22 includes a first flow-through groove 221, a second flow-through groove 222, and a third flow-through groove 223 arranged axially. The first flow-through groove 221 is disposed close to the first flow-through structure 21. The first flow-through structure 21 and the first flow-through groove 221, the first flow-through groove 221 and the second flow-through groove 222, and the second flow-through groove 222 and the third flow-through groove 223 are separated by shaft shoulders.

[0038] As a preferred embodiment, when the valve core 2 is in the neutral position, the oil port P1 near the first working oil passage 13 is connected to the oil port C via the first flow groove 221, and the other oil port P1 is connected to the oil port C via the second flow groove 222, facilitating neutral position unloading. When the valve core 2 is in the raised position, the oil port P1 near the first working oil passage 13 is connected to the first working oil passage 13 via the first flow structure 21. The shoulder between the first flow structure 21 and the first flow groove 221 blocks the connection between the oil port P1 near the first working oil passage 13 and the oil port C. The shoulder between the first flow groove 221 and the second flow groove 222 blocks the connection between the other oil port P1 and the oil port C, thus disconnecting the pressure oil passage 11 from the unloading oil passage. When valve core 2 is in the small floating position, the oil port P1 near the first working oil passage 13 is connected to oil port C via the first flow groove 221, and the other oil port P1 is connected to oil port C via the second flow groove 222. The pressure oil passage 11 is connected to the unloading oil passage. When valve core 2 is in the high pressure drop position, the shoulder between the first flow groove 221 and the second flow groove 222 blocks the connection between oil port P1 near the first working oil passage 13 and oil port C, and the shoulder between the second flow groove 222 and the third flow groove 223 blocks the connection between the other oil port P1 and oil port C. The pressure oil passage 11 is disconnected from the unloading oil passage. When valve core 2 is in the large floating position, the oil port P1 near the first working oil passage 13 is connected to oil port C via the second flow groove 222, and the other oil port P1 is connected to oil port C via the third flow groove 223. The pressure oil passage 11 is connected to the unloading oil passage.

[0039] Specifically, the third flow-through structure 23 includes a fourth flow-through groove 231, a fifth flow-through groove 232, and a sixth flow-through groove 233 arranged axially, with the fourth flow-through groove 231 positioned close to the third flow-through groove 223. The third flow-through groove 223 and the fourth flow-through groove 231, the fourth flow-through groove 231 and the fifth flow-through groove 232, and the fifth flow-through groove 232 and the sixth flow-through groove 233 are separated by shaft shoulders.

[0040] As a preferred embodiment, when the valve core 2 is in the neutral position, the shoulder between the third flow groove 223 and the fourth flow groove 231 blocks the connection between the oil port P2 and the second working oil passage 14, and the shoulder between the fourth flow groove 231 and the fifth flow groove 232 blocks the connection between the second working oil passage 14 and the return oil passage 12. When the valve core 2 is in the raised position, the shoulder between the third flow groove 223 and the fourth flow groove 231 blocks the connection between the oil port P2 and the second working oil passage 14, and the second working oil passage 14 is connected to the return oil passage 12 via the fourth flow groove 231. When valve core 2 is in the small floating position, the shoulder between the third flow groove 223 and the fourth flow groove 231 blocks the connection between oil port P2 and the second working oil passage 14. The second working oil passage 14 is throttled and connected to the fifth flow groove 232, which is connected to the return oil passage 12. Thus, the second working oil passage 14 is throttled and connected to the return oil passage 12 via the fifth flow groove 232. When valve core 2 is in the high pressure drop position, oil port P2 is connected to the second working oil passage 14 via the fourth flow groove 231. The second working oil passage 14 is connected to the fifth flow groove 232, which is throttled and connected to the return oil passage 12. Thus, the second working oil passage 14 is throttled and connected to the return oil passage 12 via the fifth flow groove 232. After the pressurized oil enters the second working oil passage 14, it can flow into the return oil passage 12 in a small area, avoiding the phenomenon of the vehicle being stuck. When the valve core 2 is in the large floating position, the shoulder between the fourth flow groove 231 and the fifth flow groove 232 blocks the connection between the oil port P2 and the second working oil passage 14, and the second working oil passage 14 is connected to the return oil passage 12 over a large area through the sixth flow groove 233.

[0041] As a preferred technical solution in this embodiment, throttling grooves are formed on the shoulders on both sides of the fifth flow channel 232, which facilitates the throttling connection between the fifth flow channel 232 and the second working oil passage 14 and the return oil passage 12, thereby achieving flow through a small area.

[0042] As a preferred technical solution in this embodiment, the valve core 2 is driven to move by the drive assembly 6, which can be a manual handle drive, an electric control drive, etc. In this embodiment, the drive assembly 6 includes a rack and pinion structure. The rack is connected to the end of the valve core 2, and the rack meshes with the gear set. The motor drives the rack to move linearly through the gear set, thereby causing the valve core 2 to move to switch positions.

[0043] like Figure 9 As shown, this embodiment also provides a hydraulic system, including a pump 7, a control valve, and an actuator 8. The pump 7 is used to pump out pressurized oil, and the outlet of the pump 7 is connected to the pressure oil passage 11 of the control valve. The control valve is used to control the oil inlet and outlet of the actuator 8. When the hydraulic system is used in structures such as tractors, the actuator 8 is used to drive the attachments.

[0044] As a preferred technical solution in this embodiment, the actuator 8 is a hydraulic cylinder, which has a rod chamber and a rodless chamber. The rod chamber of the actuator 8 is connected to the first working oil passage 13 of the control valve, and the rodless chamber of the actuator 8 is connected to the second working oil passage 14 of the control valve.

[0045] As a preferred technical solution in this embodiment, the hydraulic system may also include other working links for controlling other actuators.

[0046] Based on the above technical solution, the working principle of the hydraulic system in this embodiment in controlling the action of actuator 8 is as follows: Pump 7 pumps pressurized oil to pressurized oil passage 11. When actuator 8 is not working, valve core 2 is in the neutral position. Figure 2 , 9 As shown, the pressure oil passage 11, the return oil passage 12 and the two working oil passages are not connected. The oil port P1 and the oil port C are connected. The pressure oil flows out of the valve body 1 through the unloading oil passage. If all other working connections are in the neutral position, the pressure oil can be directly unloaded to the oil tank 9.

[0047] like Figure 3 , 9 As shown, when the valve core 2 is displaced to the rising position, the oil port P1 is connected to the first working oil passage 13, and the second working oil passage 14 is connected to the return oil passage 12. The pressurized oil enters the first working oil passage 13 through the first flow passage 21, and then enters the rodless chamber of the actuator 8, where oil enters. The oil in the rod chamber of the actuator 8 flows to the second working oil passage 14, and then flows to the return oil passage 12 through the fourth flow groove 231, where oil returns to the rod chamber. The piston of the actuator 8 extends, driving the attachment to achieve the rising action.

[0048] like Figure 4 , 9 As shown, when the valve core 2 is displaced to the small floating position, oil port P1 connects with oil port C, and the pressure oil entering from the pressure oil passage 11 flows to the unloading oil passage for unloading; the first working oil passage 13 is connected to the return oil passage 12 via the first flow structure 21 with a small area; the second working oil passage 14 is connected to the return oil passage 12 via the fifth flow groove 232 with a small area. At the small floating position, influenced by the weight of the attachment and terrain, the actuator 8 can float freely, returning oil to the oil tank or replenishing oil from the tank. Due to the influence of the valve core's oil passage opening area, throttling is formed through the small opening area, thus creating back pressure. Under the action of back pressure, as the attachment is lifted into the air and the valve core 2 moves to the small floating position and descends due to its own weight, the descent speed is limited, protecting the attachment from damage due to a rapid fall to the ground. The small floating position can also meet suitable floating working scenarios.

[0049] like Figure 5 , 9As shown, when valve core 2 is displaced to the high-pressure drop position, the first working oil passage 13 connects with the return oil passage 12, and oil port P2 connects with the second working oil passage 14. The second working oil passage 14 is connected to the return oil passage 12 via the fifth flow channel 232. With this configuration, oil enters the rod chamber of the actuator 8, pressing the attachment to the target depth below the ground without causing the vehicle to stall. The specific principle is as follows: Under actual working conditions, the load pressure P1 required for the forced descent to press the attachment into the ground is less than the load pressure P2 of the support vehicle. When the pressure P in the rod chamber of the valve core 2 to the actuator 8 is less than P1, due to the limited oil passage area from the second working oil passage 14 to the fifth flow channel 232, the pressure difference before and after the oil passage area is small. This small area and small pressure difference approach dead chamber pressure, which can suppress the pressure in the rod chamber of the actuator 8. When P is greater than P1, a forced descent action is performed, pressing the attachment into the ground. When the attachment reaches the target depth or the end of its stroke, the pressure P becomes the true dead chamber pressure. As the pressure rises, a sufficient pressure difference is achieved before P reaches P2, allowing all the flow output from the pump 7 to be unloaded and returned to the oil tank 9 through the throttling oil passage from the second working oil passage 14 to the fifth flow channel 232, even with a high pressure difference and a small oil passage area.

[0050] By setting the high-pressure drop position, the second working oil passage 14 and the return oil passage 12 are connected with a small area to prevent the vehicle from being supported. The key point is the matching of the flow area and the pressure. According to the orifice outflow formula, the flow rate is proportional to the flow area. The size of the flow area can be set well. When the pressure difference ΔP is very small, the flow capacity is poor, and pressure can be formed in the rod chamber of the actuator 8 to achieve the function of high-pressure drop. After the high-pressure drop is completed, the pressure in the rod chamber rises because the rod chamber can no longer continue to receive oil. When the pressure in the rod chamber is not enough to support the vehicle, ΔP is sufficient to allow all the flow output by the pump 7 to be throttled back to the oil tank, completing the unloading.

[0051] like Figure 6 , 9 As shown, when the valve core 2 is displaced to the large floating position, oil port P1 connects with oil port C, and the pressure oil entering from the pressure oil passage 11 flows to the unloading oil passage for unloading; the first working oil passage 13 is connected to the return oil passage 12 over a large area via the first flow structure 21; the second working oil passage 14 is connected to the return oil passage 12 over a large area via the sixth flow groove 232. Due to the influence of the attachment's own weight and terrain, the actuator 8 can float freely, returning oil to the oil tank 9 or replenishing oil from the oil tank 9. At this time, the flow area of ​​the valve core 2 is large. When encountering complex working environments with large undulations or many debris, and requiring the actuator 8 to float up and down over a large range, the large floating position is more suitable.

[0052] Example 2

[0053] like Figure 10-11As shown, this embodiment is basically the same as embodiment one, except that when the pressure drops to the lower position, the pressure oil introduced by the pressure oil passage 11 is throttled and unloaded through the unloading oil circuit to avoid the phenomenon of the vehicle being stuck. Specifically, when the valve core 2 is in the lower position, the oil port P1 near the oil port P2 and the oil port C are connected through the second flow groove 222 with a small area, and the pressure oil can be throttled and unloaded through the unloading oil circuit.

[0054] As a preferred technical solution of this embodiment, a throttling groove is formed on the shoulder between the second flow groove 222 and the third flow groove 223, which communicates with the second flow groove 222. When the valve core 2 is in the strong pressure drop position, the oil port P1 near the oil port P2 communicates with the second flow groove 222 through the throttling groove, and the oil port C communicates with the second flow groove 222. Then, the pressure oil entering through the oil port P1 near the oil port P2 can enter the second flow groove 222 through the throttling groove, and then enter the oil port C, realizing a small area connection between the oil port P1 and the oil port C.

[0055] As a preferred technical solution in this embodiment, the axial length of the third flow channel 223 can be appropriately reduced and the axial length of the second flow channel 222 can be increased to meet the above-mentioned communication requirements.

[0056] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A control valve, characterized in that, include: The valve body (1) has a pressure oil passage (11), a return oil passage (12) and two working oil passages inside, namely the first working oil passage (13) and the second working oil passage (14). The valve core (2) is assembled inside the valve body (1) and slides to switch positions. The valve core (2) can be located in the rising position, the middle position and the high pressure drop position. There is also a small floating position between the middle position and the high pressure drop position. When the valve core (2) is in the small floating position, the two working oil passages are throttled and connected to the return oil passage (12). After the valve core (2) passes through the high pressure drop position, it can continue to move to the large floating position, controlling the two working oil passages to be fully connected to the return oil passage (12).

2. A control valve according to claim 1, characterized in that, The valve body (1) also has an unloading oil passage. When the valve core (2) is in the middle position, small floating position and large floating position, the pressure oil in the pressure oil passage (11) is unloaded through the unloading oil passage.

3. A control valve according to claim 2, characterized in that, When the valve core (2) is in the high pressure drop position, the pressure oil introduced by the pressure oil passage (11) is throttled and unloaded.

4. A control valve according to claim 3, characterized in that, When the valve core (2) is in the high pressure drop position, the second working oil passage (14) connected to the pressure oil passage (11) is throttled and connected to the return oil passage (12); or, the pressure oil passage (11) is throttled and connected to the unloading oil passage.

5. A control valve according to any one of claims 2-4, characterized in that, Two working oil passages are arranged on both sides of the pressure oil passage (11), and the return oil passage (12) extends to both sides of the two working oil passages. The pressure oil passage (11) introduces pressure oil to oil port P1 and oil port P2. The unloading oil passage extends to the outer periphery of the valve core (2) to form oil port C. There are two oil ports P1, located on both sides of oil port C respectively. Oil port P2 is located between the second working oil passage (14) and the adjacent oil port P1.

6. A control valve according to claim 5, characterized in that, A first flow passage structure (21) is formed on the valve core (2) to control the connection between the oil port P1, the first working oil passage (13) and the return oil passage (12); when the valve core (2) is in a small floating position, the first working oil passage (13) is connected to the first flow passage structure (21), and the first flow passage structure (21) is connected to the return oil passage (12) in a throttling manner.

7. A control valve according to claim 5, characterized in that, A second flow passage structure (22) is formed on the valve core (2) to control the connection between oil port P1 and oil port C. The second flow passage structure (22) includes a first flow passage (221), a second flow passage (222), and a third flow passage (223) arranged axially. A third flow passage structure (23) is formed on the valve core (2) to control the connection between oil port P2, the second working oil passage (14), and the return oil passage (12). The third flow passage structure (23) includes a fourth flow passage (231), a fifth flow passage (232), and a sixth flow passage (2333) arranged axially.

8. A control valve according to claim 7, characterized in that, When the pressure drops, the second working oil passage (14) is throttled and connected to the fifth flow channel (232), and the fifth flow channel (232) is fully connected to the return oil passage (12); or, the oil port P1 is throttled and connected to the second flow channel (222), and the second flow channel (222) is fully connected to the oil port C.

9. A control valve according to claim 1, characterized in that, The valve body (1) also has a connecting oil passage (15), the second working oil passage (14) is connected to the return oil passage (12) through the connecting oil passage (15), and a single-acting or double-acting switching valve (3) is provided on the connecting oil passage (15).

10. A hydraulic system, characterized in that, include: Pump (7); The control valve according to any one of claims 1-9, wherein the outlet of the pump (7) is connected to the pressure oil passage (11); The actuator (8) has a rod chamber and a rodless chamber. The rodless chamber is connected to the first working oil passage (13), and the rod chamber is connected to the second working oil passage (14).

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