A loader hydraulic system

Abstract

This utility model relates to the field of hydraulic control technology, and provides a hydraulic system for a loader, including a main directional valve group, an external control directional valve group, a working pump, a locking protection module, a left attachment cylinder, and a right attachment cylinder; the locking protection module includes a first hydraulic lock and a second hydraulic lock; the hydraulic system of the circular tube clamp is improved by adding a first hydraulic lock and a second hydraulic lock between the left attachment cylinder, the right attachment cylinder and the external control directional valve group, and the hydraulic lock provides a self-locking mechanism, which closes the large chambers of the left attachment cylinder and the right attachment cylinder when the directional valve is in the neutral position, ensuring that the load is stationary. When the large chamber of the loader attachment cylinder is under long-distance transportation and high-pressure conditions, it effectively prevents oil leakage from the large chamber of the cylinder (reducing internal leakage during long-distance transportation and high-pressure boom conditions), ensuring the clamping effect of the circular tube clamp, thereby enhancing the working stability of the hydraulic system, optimizing the structure of the hydraulic system, and improving the overall performance of the machine.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control technology, and in particular to a hydraulic system for a loader. Background Technology

[0002] In loaders, pipe clamps are attachments specifically designed for the efficient handling, stacking, and loading / unloading of long tubular materials (such as steel pipes, cement pipes, HDPE pipes, etc.). Driven by a hydraulic system, the clamping mechanism enables rapid gripping, lifting, and placement of pipes, and is widely used in building materials, ports, logistics, and pipeline construction.

[0003] The hydraulic system of a tube clamp is its core power transmission and control component, responsible for achieving clamping, lifting, and rotation actions. In existing hydraulic system technologies for tube clamps, the hydraulic drive component includes: Clamping cylinder: Double-acting cylinder, providing stable clamping force (typically 10-30 tons of pressure on one side).

[0004] Lifting cylinder: Linked with the loader boom, it controls the lifting and lowering of the clamps.

[0005] Rotary cylinder / motor (if equipped): used to adjust the angle of the pipe.

[0006] In the clamping cylinder, the working pump is a gear pump, and the steering pump is a variable displacement piston pump. The left and right sets of attachment cylinders cooperate to achieve corresponding actions: the round pipe with oil in the large chamber clamps (closes), and the round pipe with oil in the small chamber loosens (opens). When the attachment cylinder is working, the steering pump provides pilot oil flow. The externally controlled two-position three-way solenoid valve is not energized and is in the upper position. At this time, the two-position six-way externally controlled pilot valve is in the right position. Oil supplied by the working pump passes through the left position of the main control valve (three-position six-way directional valve) and enters the large chamber, completing the closing action of the left attachment cylinder. Conversely, it enters the small chamber, realizing the opening action of the left attachment cylinder. When the externally controlled two-position three-way solenoid valve is energized and is in the lower position, the pilot oil flow provided by the steering pump causes the two-position six-way externally controlled pilot valve to be in the left position, realizing the opening and closing action of the right attachment cylinder in the same way. Among them, due to the large flow requirement of the two six-way external control pilot directional valves, and the high pressure condition of the boom cavity in the long and harsh transportation section, the self-locking ability of each directional valve is limited and there is internal leakage, which causes oil to leak from the large cavity of the two sets of attachment cylinders, resulting in the inability to clamp the round pipe. Utility Model Content

[0007] This utility model provides a hydraulic system for a loader, which solves the technical problem that the existing hydraulic system for round pipe clamps uses a two-position six-way externally controlled pilot directional valve, which has limited self-locking capability, poses a risk of internal leakage, and thus causes the round pipe to fail to be clamped.

[0008] To solve the above technical problems, this utility model provides a loader hydraulic system, including a main directional valve group, an external control directional valve group, a working pump, a locking protection module, a left attachment cylinder, and a right attachment cylinder; the locking protection module includes a first hydraulic lock and a second hydraulic lock; the oil inlet of the main directional valve group is connected to the working pump, and the oil outlet is connected to the external control directional valve group; one oil outlet A1 of the external control directional valve group is connected to the left attachment cylinder through the first hydraulic lock, and the other oil outlet A2 is connected to the right attachment cylinder through the second hydraulic lock.

[0009] This basic solution improves the hydraulic system of the pipe clamp by adding a first hydraulic lock and a second hydraulic lock between the left and right attachment cylinders and the external control directional valve group. The hydraulic locks provide a self-locking mechanism, which closes the large chambers of the left and right attachment cylinders when the directional valve is in the neutral position, ensuring that the load is stationary. When the large chambers of the loader attachment cylinders are in long-distance transportation and high-pressure conditions, it effectively prevents oil leakage from the large chambers of the cylinders, ensuring the clamping effect of the pipe clamp and thus enhancing the working stability of the hydraulic system.

[0010] In a further embodiment, the main directional valve assembly includes a main control valve, a damping orifice, a first electrically controlled pilot valve, and a second electrically controlled pilot valve; the left pilot control terminal of the main control valve is connected to the first electrically controlled pilot valve, the right pilot control terminal is connected to the second electrically controlled pilot valve through the damping orifice, the oil inlet is connected to the working pump, and the oil outlet is connected to the externally controlled directional valve assembly; Based on the throttling effect of the damping orifice, the pilot pressure build-up speed of the main control valve is slowed down, so that the opening of the first hydraulic lock / second hydraulic lock precedes the opening of the main control valve.

[0011] This solution adds a damping orifice between the main control valve and the second electrically controlled pilot valve. When the oil circuit is not open, it ensures the self-locking of the oil circuit. When the oil circuit needs to be opened, the damping orifice ensures that the opening of the first hydraulic lock / second hydraulic lock precedes the action of the main control valve. The main control valve only starts supplying oil after the first hydraulic lock / second hydraulic lock is fully opened. This avoids abnormal shaking or even equipment failure during load descent caused by the main control valve acting first, thereby ensuring that the load can descend smoothly and improving the safety and stability of the system.

[0012] In a further embodiment, a pilot oil circuit is also included, which includes a steering pump, a relief valve, and a pressure reducing valve; the inlet of the pressure reducing valve is connected to the steering pump, and the outlet is connected to the inlet of the first electronically controlled pilot valve and the inlet of the second electronically controlled pilot valve, and the outlet is also connected to the fuel tank through the relief valve; the return ports of the first electronically controlled pilot valve and the second electronically controlled pilot valve are connected to the fuel tank.

[0013] This solution incorporates a pressure reducing valve to reduce the pressure of the hydraulic fluid supplied by the steering pump, thereby obtaining pilot hydraulic fluid and ensuring a stable pilot control signal. An overflow valve is also included to prevent excessive pressure in the pilot hydraulic circuit, protecting the hydraulic circuit components from damage and avoiding the risk of pipeline rupture.

[0014] In a further embodiment, the externally controlled directional valve group includes a first externally controlled directional valve and a first externally controlled pilot directional valve. The oil inlet of the first externally controlled directional valve is connected to the oil outlet of the pressure reducing valve, and the oil outlet is connected to the pilot control end of the first externally controlled pilot directional valve. The oil inlet of the first externally controlled pilot directional valve is connected to the oil outlet of the main directional valve group. Oil outlet A1 is connected to one side of the left attachment cylinder through the first hydraulic lock, and oil outlet B1 is connected to the other side of the left attachment cylinder. Oil outlet A2 is connected to the right attachment cylinder through the second hydraulic lock, and oil outlet B2 is connected to the other side of the right attachment cylinder.

[0015] In a further embodiment, the first externally controlled directional valve is electrically connected to the handle switch and is an externally controlled two-position three-way solenoid directional valve; the first externally controlled pilot directional valve is a two-position ten-way externally controlled pilot directional valve.

[0016] This solution is based on the pilot start control of the first and second hydraulic locks. A two-position ten-way external pilot directional valve is set as the first external pilot directional valve. It triggers the oil circuit signal of the pilot oil port of the first and second hydraulic locks to perform the pre-opening relative to the main control valve. At the same time, the first external pilot directional valve is electrically connected to the handle switch to obtain the user's operation in real time and switch the working position of the left attachment cylinder and the right attachment cylinder. Then, in conjunction with the main control valve, the oil circuit is switched to perform the clamping-release action switching of the corresponding attachment cylinder. The circuit is simple and compact, reducing pipeline connections, reducing installation volume, and reducing leakage risk.

[0017] In a further embodiment, the first hydraulic lock includes a first check valve and a second directional valve. The inlet of the first check valve is connected to one side outlet A1 of the externally controlled directional valve assembly, and the outlet is connected to one side of the left attachment cylinder. The pilot port is connected to the inlet of the second directional valve. The pilot control end of the second directional valve is connected to the first externally controlled pilot directional valve. The second hydraulic lock includes a second check valve and a third directional valve. The oil inlet of the second check valve is connected to the oil outlet A2 on the other side of the externally controlled directional valve group, and the oil outlet is connected to one side of the right attachment cylinder. The pilot oil port is connected to the oil inlet of the third directional valve. The pilot control end of the third directional valve is connected to the first externally controlled pilot directional valve.

[0018] This design incorporates a hydraulic lock composed of check valves (first and second check valves) and hydraulically controlled directional valves (second and third directional valves), providing self-locking services for the left and right attachment cylinders respectively. When the system stops working, the check valves close their inlets and connect their outlets to the pilot ports under the action of the directional valves, thus locking the hydraulic fluid in the large chamber of the cylinder. After the directional valves are triggered by the pilot oil, the pilot oil pushes open the check valves, allowing bidirectional flow of hydraulic fluid, and the cylinders can operate normally. This design features a self-locking mechanism with strong self-locking capability and low manufacturing cost.

[0019] In a further embodiment, the externally controlled directional valve group includes a second externally controlled directional valve, a second externally controlled pilot directional valve, and a first directional valve; The oil inlet of the second externally controlled directional valve is connected to the oil outlet of the pressure reducing valve, and the oil outlet is connected to one side of the pilot control terminal of the second externally controlled pilot directional valve. The oil inlet of the second externally controlled pilot directional valve is connected to the oil outlet of the main directional valve assembly. Oil outlet A1 is connected to one side of the left attachment cylinder through the first hydraulic lock, and oil outlet B1 is connected to the other side of the left attachment cylinder. Oil outlet A2 is connected to the right attachment cylinder through the second hydraulic lock, and oil outlet B2 is connected to the other side of the right attachment cylinder. The oil inlet b1 of the first directional valve is connected to the oil outlet of the second electrically controlled pilot valve, the oil inlet a1 is connected to the oil tank, and the two oil outlets are respectively connected to the pilot control terminals of the first hydraulic lock and the second hydraulic lock.

[0020] In a further embodiment, the second externally controlled directional valve is electrically connected to the handle switch and is an externally controlled two-position three-way solenoid directional valve; the second externally controlled pilot directional valve is a two-position six-way externally controlled pilot directional valve, and the first directional valve is a two-position four-way solenoid directional valve.

[0021] This solution differs from the first externally controlled pilot directional valve of the two-position ten-way externally controlled pilot directional valve. It designs a second externally controlled pilot directional valve and a first directional valve to control the main oil circuit and the pilot oil circuit respectively. The oil circuit isolation is conducive to performing precise timing regulation. Selecting a two-position six-way externally controlled pilot directional valve can effectively reduce costs and improve response speed.

[0022] In a further embodiment, the first hydraulic lock includes a first check valve and a second directional valve. The inlet of the first check valve is connected to one side outlet A1 of the externally controlled directional valve assembly, and the outlet is connected to one side of the left attachment cylinder. The pilot port is connected to the inlet of the second directional valve. The pilot control end of the second directional valve is connected to the outlet of the first directional valve. The second hydraulic lock includes a second check valve and a third directional valve. The oil inlet of the second check valve is connected to the oil outlet A2 on the other side of the external control directional valve group, and the oil outlet is connected to one side of the right attachment cylinder. The pilot oil port is connected to the oil inlet of the third directional valve. The pilot control end of the third directional valve is connected to the oil outlet of the first directional valve.

[0023] In a further embodiment, both the second directional valve and the third directional valve are two-position three-way hydraulically controlled directional valves. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of a loader hydraulic system provided in Embodiment 1 of this utility model; Figure 2 This is a three-dimensional structural diagram of a loader hydraulic system provided in Embodiment 2 of this utility model; The components include: working pump 1, left attachment cylinder 2, right attachment cylinder 3, first hydraulic lock 4 (not shown in the figure), second hydraulic lock 5 (not shown in the figure), main control valve 6, damping orifice 7, first electric pilot valve 8, second electric pilot valve 9, oil tank 10, steering pump 11, overflow valve 12, pressure reducing valve 13, first external control directional valve 14, first external control pilot directional valve 15, second external control directional valve 16, second external control pilot directional valve 17, first directional valve 18; steering coupling 19, steering cylinder 20. First check valve 41, second directional valve 42, second check valve 51, third directional valve 52. Detailed Implementation

[0025] The embodiments of this utility model are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the utility model. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of this utility model, because many changes can be made to this utility model without departing from the spirit and scope of this utility model.

[0026] Example 1 This utility model provides a loader hydraulic system, such as Figure 1 As shown, in this embodiment, it includes a main directional valve assembly, an externally controlled directional valve assembly, a working pump 1, a locking protection module, a left attachment cylinder 2, and a right attachment cylinder 3; the locking protection module includes a first hydraulic lock 4 and a second hydraulic lock 5; the oil inlet of the main directional valve assembly is connected to the working pump 1, and the oil outlet is connected to the externally controlled directional valve assembly; one oil outlet A1 of the externally controlled directional valve assembly is connected to the left attachment cylinder 2 through the first hydraulic lock 4, and the other oil outlet A2 is connected to the right attachment cylinder 3 through the second hydraulic lock 5.

[0027] In this embodiment, the main directional valve assembly includes a main control valve 6, a damping orifice 7, a first electrically controlled pilot valve 8, and a second electrically controlled pilot valve 9; the left pilot control end of the main control valve 6 is connected to the first electrically controlled pilot valve 8, the right pilot control end is connected to the second electrically controlled pilot valve 9 through the damping orifice 7, the oil inlet is connected to the working pump 1, and the oil outlet is connected to the externally controlled directional valve assembly; Based on the throttling effect of the damping orifice 7, the pilot pressure build-up speed of the main control valve 6 is slowed down, so that the opening of the first hydraulic lock 4 / second hydraulic lock 5 precedes the opening of the main control valve 6.

[0028] Preferably, the main control valve 6 is a three-position six-way directional valve; the first electrically controlled pilot valve 8 and the second electrically controlled pilot valve 9 have the same structure and are selected as two-position three-way proportional electrically controlled pilot valves.

[0029] The working pump 1 is preferably a gear pump.

[0030] In this embodiment, a damping orifice 7 is added between the main control valve 6 and the second electrically controlled pilot valve 9. When the oil circuit is not open, the self-locking of the oil circuit is ensured. When the oil circuit needs to be opened, the damping orifice 7 ensures that the opening of the first hydraulic lock 4 / second hydraulic lock 5 precedes the action of the main control valve 6. The main control valve 6 only starts supplying oil after the first hydraulic lock 4 / second hydraulic lock 5 is fully opened. This avoids abnormal shaking or even equipment failure during load descent caused by the main control valve 6 acting first, thereby ensuring that the load can descend smoothly and improving the safety and stability of the system.

[0031] In this embodiment, a pilot oil circuit is also included, which includes a steering pump 11, an overflow valve 12, and a pressure reducing valve 13. The inlet of the pressure reducing valve 13 is connected to the steering pump 11, and the outlet is connected to the inlet of the first electronically controlled pilot valve 8 and the inlet of the second electronically controlled pilot valve 9. The outlet is also connected to the oil tank 10 through the overflow valve 12. The return ports of the first electronically controlled pilot valve 8 and the second electronically controlled pilot valve 9 are connected to the oil tank 10.

[0032] In this embodiment, the steering pump 11 is also connected to the steering cylinder 20 via the steering coupling 19; the steering pump 11 is preferably a variable displacement piston pump.

[0033] In this embodiment, a pressure reducing valve 13 is provided to reduce the pressure of the oil supplied by the steering pump 11 to obtain pilot oil, ensuring the stability of the pilot control signal; an overflow valve 12 is provided to prevent the pilot oil circuit pressure from being too high, protect the oil circuit components from being damaged, and avoid the risk of pipeline rupture.

[0034] In this embodiment, the external control directional valve group includes a first external control directional valve 14 and a first external control pilot directional valve 15. The oil inlet of the first external control directional valve 14 is connected to the oil outlet of the pressure reducing valve 13, and the oil outlet is connected to the pilot control end of the first external control pilot directional valve 15. The oil inlet of the first external control pilot directional valve 15 is connected to the oil outlet of the main directional valve group. Oil outlet A1 is connected to one side of the left attachment cylinder 2 through the first hydraulic lock 4, and oil outlet B1 is connected to the other side of the left attachment cylinder 2. Oil outlet A2 is connected to the right attachment cylinder 3 through the second hydraulic lock 5, and oil outlet B2 is connected to the other side of the right attachment cylinder 3.

[0035] In this embodiment, the first externally controlled directional valve 14 is electrically connected to the handle switch and is an externally controlled two-position three-way solenoid directional valve; the first externally controlled pilot directional valve 15 is a two-position ten-way externally controlled pilot directional valve.

[0036] This embodiment is based on the pilot start control of the first hydraulic lock 4 and the second hydraulic lock 5. A two-position ten-way external control pilot directional valve is set as the first external control pilot directional valve 15. It triggers the oil circuit signal of the pilot oil port of the first hydraulic lock 4 and the second hydraulic lock 5 to perform the prior opening relative to the main control valve 6. At the same time, the first external control directional valve 14, which is electrically connected to the handle switch, is set to obtain the user operation in real time and switch the working position of the left attachment cylinder 2 and the right attachment cylinder 3. Then, in conjunction with the main control valve 6, the oil circuit is switched to perform the clamping-release action switching of the corresponding attachment cylinder. The circuit is simple and compact, reducing pipeline connections, reducing installation volume, and reducing leakage risk.

[0037] In this embodiment, the first hydraulic lock 4 includes a first check valve 41 and a second directional valve 42. The oil inlet of the first check valve 41 is connected to one side of the oil outlet A1 of the externally controlled directional valve assembly, and the oil outlet is connected to one side of the left attachment cylinder 2. The pilot oil port is connected to the oil inlet of the second directional valve 42. The pilot control end of the second directional valve 42 is connected to the first externally controlled pilot directional valve 15. The second hydraulic lock 5 includes a second check valve 51 and a third directional valve 52. The oil inlet of the second check valve 51 is connected to the oil outlet A2 on the other side of the external control directional valve group, and the oil outlet is connected to one side of the right attachment cylinder 3. The pilot oil port is connected to the oil inlet of the third directional valve 52. The pilot control end of the third directional valve 52 is connected to the first external control pilot directional valve 15.

[0038] In this embodiment, both the second reversing valve 42 and the third reversing valve 52 are two-position three-way hydraulically controlled reversing valves.

[0039] This embodiment features a hydraulic lock composed of check valves (first check valve 41 and second check valve 51) and hydraulically controlled directional valves (second directional valve 42 and third directional valve 52), providing self-locking services for the left attachment cylinder 2 and the right attachment cylinder 3, respectively. When the system stops working, under the action of the directional valves, the inlet of the check valve closes, and the outlet is connected to the pilot port, thereby controlling the oil lock in the large chamber of the cylinder. After the directional valve is triggered by the pilot oil, the pilot oil pushes open the check valve, allowing bidirectional oil flow, and the cylinder can operate normally. The self-locking mechanism designed in this embodiment has strong self-locking capability and low manufacturing cost.

[0040] The working principle of the hydraulic system in this embodiment is as follows: When the main control valve 6 is in the neutral position, if the left / right attachment cylinder 3 is in the engaged state, the second reversing valve 42 and the third reversing valve 52 are in the left position, and the first check valve 41 and the second check valve 51 are closed (the oil inlet of the check valve is closed, and the oil outlet is connected to the pilot oil port) to prevent leakage in the large chamber of the attachment cylinder.

[0041] When the steering pump 11 starts, the outlet of the pressure reducing valve 13 outputs pilot oil to the first electrically controlled pilot valve 8, the second electrically controlled pilot valve 9, and the first externally controlled directional valve 14. At this time, the oil output from the outlet of the second electrically controlled pilot valve 9 flows through the first externally controlled pilot directional valve 15 into the pilot port of the second directional valve 42 / third directional valve 52 (wherein, when the first directional valve 18 is in the right position, it controls the second directional valve 42 to start; when the first directional valve 18 is in the left position, it controls the third directional valve 52 to start), triggering the first check valve 41 or the second check valve 51 to unlock. Simultaneously, due to the effect of the damping orifice 7, the opening of the first hydraulic lock 4 / second hydraulic lock 5 precedes the opening of the main control valve 6.

[0042] When the main control valve 6 is in the right position (the oil inlet to both the large and small chambers of the attachment cylinder is controlled by the main control valve 6), the first external control pilot directional valve 15 (two-position ten-way external control pilot directional valve) is also in the right position. At this time, the oil flow enters the small chamber, causing the left attachment cylinder to open. The steering pump 11 provides pilot oil flow through the second electrically controlled pilot valve 9 to the right of the main control valve 6, then through the first external control pilot directional valve 15 to the pilot port of the second directional valve 42. The valve core of the second directional valve 42 moves to the left. At this time, the spring chamber of the first check valve 41 connects to the oil tank 10, the large chamber of the left attachment cylinder 2 is unlocked, and the large chamber of the right attachment cylinder is unaffected. Similarly, when the first external control pilot directional valve 15 is in the left position, the large chamber of the right attachment cylinder is unlocked, and the large chamber of the left attachment cylinder is unaffected.

[0043] Example 2 This utility model provides a loader hydraulic system, such as Figure 2 As shown, the difference between this embodiment and Embodiment 1 lies in the externally controlled directional valve assembly, as detailed below: In this embodiment, the externally controlled directional valve group includes a second externally controlled directional valve 16, a second externally controlled pilot directional valve 17, and a first directional valve 18; The oil inlet of the second externally controlled directional valve 16 is connected to the oil outlet of the pressure reducing valve 13, and the oil outlet is connected to one side of the pilot control terminal of the second externally controlled pilot directional valve 17. The oil inlet of the second externally controlled pilot directional valve 17 is connected to the oil outlet of the main directional valve assembly. Oil outlet A1 is connected to one side of the left attachment cylinder 2 through the first hydraulic lock 4, and oil outlet B1 is connected to the other side of the left attachment cylinder 2. Oil outlet A2 is connected to the right attachment cylinder 3 through the second hydraulic lock 5, and oil outlet B2 is connected to the other side of the right attachment cylinder 3. The oil inlet b1 of the first reversing valve 18 is connected to the oil outlet of the second electronically controlled pilot valve 9, the oil inlet a1 is connected to the oil tank 10, and the two oil outlets are respectively connected to the pilot control terminals of the first hydraulic lock 4 and the second hydraulic lock 5.

[0044] In this embodiment, the second externally controlled directional valve 16 is electrically connected to the handle switch and is an externally controlled two-position three-way solenoid directional valve; the second externally controlled pilot directional valve 17 is a two-position six-way externally controlled pilot directional valve, and the first directional valve 18 is a two-position four-way solenoid directional valve.

[0045] This embodiment differs from the first externally controlled pilot directional valve 15 of the two-position ten-way externally controlled pilot directional valve. It designs a second externally controlled pilot directional valve 17 and a first directional valve 18 to control the main oil circuit and the pilot oil circuit respectively. The oil circuit isolation is conducive to performing precise timing regulation. Selecting a two-position six-way externally controlled pilot directional valve can effectively reduce costs and improve response speed.

[0046] In this embodiment, the first hydraulic lock 4 includes a first check valve 41 and a second directional valve 42. The oil inlet of the first check valve 41 is connected to one side of the oil outlet A1 of the externally controlled directional valve assembly, and the oil outlet is connected to one side of the left attachment cylinder 2. The pilot oil port is connected to the oil inlet of the second directional valve 42. The pilot control end of the second directional valve 42 is connected to the oil outlet of the first directional valve 18. The second hydraulic lock 5 includes a second check valve 51 and a third directional valve 52. The oil inlet of the second check valve 51 is connected to the oil outlet A2 on the other side of the external control directional valve group, and the oil outlet is connected to one side of the right attachment cylinder 3. The pilot oil port is connected to the oil inlet of the third directional valve 52. The pilot control end of the third directional valve 52 is connected to the oil outlet of the first directional valve 18.

[0047] In this embodiment, both the second reversing valve 42 and the third reversing valve 52 are two-position three-way hydraulically controlled reversing valves.

[0048] The working principle of the hydraulic system in this embodiment is as follows: When the main control valve 6 is in the neutral position, if the left / right accessory cylinder 3 is in the engaged state, the second directional valve 42 and the third directional valve 52 are in the left position, and the first check valve 41 and the second check valve 51 are closed (the oil inlet of the check valve is closed, and the oil outlet is connected to the pilot oil port) to prevent internal leakage in the large chamber of the accessory cylinder; that is, when the clamping action is performed, the large chambers of the left and right accessory cylinders 3 are locked, and the individual actions do not interfere with each other, thereby reducing the risk of internal leakage.

[0049] When the steering pump 11 starts, the outlet of the pressure reducing valve 13 outputs pilot oil to the first electrically controlled pilot valve 8, the second electrically controlled pilot valve 9, and the second externally controlled directional valve 16. At this time, the oil output from the outlet of the second electrically controlled pilot valve 9 flows into the first directional valve 18, and then into the pilot port of the second directional valve 42 / third directional valve 52 (wherein, when the first directional valve 18 is in the right position, it controls the second directional valve 42 to start; when the first directional valve 18 is in the left position, it controls the third directional valve 52 to start), triggering the first check valve 41 or the second check valve 51 to unlock. At the same time, due to the effect of the damping orifice 7, the opening of the first hydraulic lock 4 / second hydraulic lock 5 is before the opening of the main control valve 6; ensuring that the hydraulic locks, which are far from the main control valve 6 and subject to high loads, can still guarantee the unlocking function.

[0050] When the main control valve 6 is in the right position (the oil inlet to both the large and small chambers of the attachment cylinder is controlled by the main control valve 6), the second external control pilot directional valve 17 is also in the right position. At this time, the oil flow enters the small chamber, causing the left attachment cylinder to open. The steering pump 11 provides pilot oil flow through the second electrically controlled pilot valve 9 to the right of the main control valve 6, then through the first directional valve 18 to the pilot port of the second directional valve 42. The valve core of the second directional valve 42 moves to the left. At this time, the spring chamber of the first check valve 41 connects to the oil tank 10, unlocking the large chamber of the left attachment cylinder 2, while the large chamber of the right attachment cylinder remains unaffected. Similarly, when the second external control pilot directional valve 17 is in the left position, the large chamber of the right attachment cylinder is unlocked, while the large chamber of the left attachment cylinder remains unaffected.

[0051] This utility model embodiment improves the hydraulic system of the circular tube clamp by adding a first hydraulic lock 4 and a second hydraulic lock 5 between the left attachment cylinder 2, the right attachment cylinder 3 and the external control directional valve group. The hydraulic locks provide a self-locking mechanism, which closes the large chambers of the left attachment cylinder 2 and the right attachment cylinder 3 when the directional valve is in the neutral position, ensuring that the load is stationary. When the large chambers of the loader attachment cylinders are in long-distance transportation and high-pressure conditions, it effectively prevents oil leakage from the large chambers of the cylinders (reducing internal leakage during long-distance transportation and high-pressure boom conditions), ensuring the clamping effect of the circular tube clamp, thereby enhancing the working stability of the hydraulic system, optimizing the structure of the hydraulic system, and improving the overall performance of the machine.

[0052] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A hydraulic system for a loader, characterized in that: It includes a main directional valve assembly, an externally controlled directional valve assembly, a working pump, a locking protection module, a left attachment cylinder, and a right attachment cylinder; the locking protection module includes a first hydraulic lock and a second hydraulic lock; the oil inlet of the main directional valve assembly is connected to the working pump, and the oil outlet is connected to the externally controlled directional valve assembly; one oil outlet A1 of the externally controlled directional valve assembly is connected to the left attachment cylinder through the first hydraulic lock, and the other oil outlet A2 is connected to the right attachment cylinder through the second hydraulic lock.

2. The loader hydraulic system as described in claim 1, characterized in that: The main directional valve assembly includes a main control valve, a damping orifice, a first electrically controlled pilot valve, and a second electrically controlled pilot valve; the left pilot control terminal of the main control valve is connected to the first electrically controlled pilot valve, the right pilot control terminal is connected to the second electrically controlled pilot valve through the damping orifice, the oil inlet is connected to the working pump, and the oil outlet is connected to the externally controlled directional valve assembly. Based on the throttling effect of the damping orifice, the pilot pressure build-up speed of the main control valve is slowed down, so that the opening of the first hydraulic lock / second hydraulic lock precedes the opening of the main control valve.

3. The loader hydraulic system as described in claim 2, characterized in that: It also includes a pilot oil circuit, which includes a steering pump, a relief valve, and a pressure reducing valve; the inlet of the pressure reducing valve is connected to the steering pump, and the outlet is connected to the inlet of the first electronically controlled pilot valve and the inlet of the second electronically controlled pilot valve. The outlet is also connected to the fuel tank through the relief valve; the return ports of the first electronically controlled pilot valve and the second electronically controlled pilot valve are connected to the fuel tank.

4. A loader hydraulic system as described in claim 3, characterized in that: The externally controlled directional valve assembly includes a first externally controlled directional valve and a first externally controlled pilot directional valve. The inlet of the first externally controlled directional valve is connected to the outlet of the pressure reducing valve, and the outlet is connected to the pilot control end of the first externally controlled pilot directional valve. The inlet of the first externally controlled pilot directional valve is connected to the outlet of the main directional valve assembly. Outlet A1 is connected to one side of the left attachment cylinder via the first hydraulic lock, and outlet B1 is connected to the other side of the left attachment cylinder. Outlet A2 is connected to the right attachment cylinder via the second hydraulic lock, and outlet B2 is connected to the other side of the right attachment cylinder.

5. A loader hydraulic system as described in claim 4, characterized in that: The first hydraulic lock includes a first check valve and a second directional valve. The oil inlet of the first check valve is connected to the oil outlet A1 on one side of the externally controlled directional valve assembly, and the oil outlet is connected to one side of the left attachment cylinder. The pilot oil port is connected to the oil inlet of the second directional valve. The pilot control end of the second directional valve is connected to the first externally controlled pilot directional valve. The second hydraulic lock includes a second check valve and a third directional valve. The oil inlet of the second check valve is connected to the oil outlet A2 on the other side of the externally controlled directional valve group, and the oil outlet is connected to one side of the right attachment cylinder. The pilot oil port is connected to the oil inlet of the third directional valve. The pilot control end of the third directional valve is connected to the first externally controlled pilot directional valve.

6. A loader hydraulic system as described in claim 3, characterized in that: The externally controlled directional valve group includes a second externally controlled directional valve, a second externally controlled pilot directional valve, and a first directional valve; The oil inlet of the second externally controlled directional valve is connected to the oil outlet of the pressure reducing valve, and the oil outlet is connected to one side of the pilot control terminal of the second externally controlled pilot directional valve. The oil inlet of the second externally controlled pilot directional valve is connected to the oil outlet of the main directional valve assembly. Oil outlet A1 is connected to one side of the left attachment cylinder through the first hydraulic lock, and oil outlet B1 is connected to the other side of the left attachment cylinder. Oil outlet A2 is connected to the right attachment cylinder through the second hydraulic lock, and oil outlet B2 is connected to the other side of the right attachment cylinder. The oil inlet b1 of the first directional valve is connected to the oil outlet of the second electrically controlled pilot valve, the oil inlet a1 is connected to the oil tank, and the two oil outlets are respectively connected to the pilot control terminals of the first hydraulic lock and the second hydraulic lock.

7. A loader hydraulic system as described in claim 6, characterized in that: The first hydraulic lock includes a first check valve and a second directional valve. The oil inlet of the first check valve is connected to the oil outlet A1 on one side of the externally controlled directional valve assembly, and the oil outlet is connected to one side of the left attachment cylinder. The pilot oil port is connected to the oil inlet of the second directional valve. The pilot control end of the second directional valve is connected to the oil outlet of the first directional valve. The second hydraulic lock includes a second check valve and a third directional valve. The oil inlet of the second check valve is connected to the oil outlet A2 on the other side of the external control directional valve group, and the oil outlet is connected to one side of the right attachment cylinder. The pilot oil port is connected to the oil inlet of the third directional valve. The pilot control end of the third directional valve is connected to the oil outlet of the first directional valve.

8. A loader hydraulic system as described in claim 4, characterized in that: The first externally controlled directional valve is electrically connected to the handle switch and is an externally controlled two-position three-way solenoid directional valve; the first externally controlled pilot directional valve is a two-position ten-way externally controlled pilot directional valve.

9. A loader hydraulic system as described in claim 6, characterized in that: The second externally controlled directional valve is electrically connected to the handle switch and is an externally controlled two-position three-way solenoid directional valve; the second externally controlled pilot directional valve is a two-position six-way externally controlled pilot directional valve, and the first directional valve is a two-position four-way solenoid directional valve.

10. A loader hydraulic system as described in claim 7, characterized in that: Both the second and third directional valves are two-position three-way hydraulically controlled directional valves.

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