Load automatic feedback hydraulic device and trencher

Abstract

The utility model provides a load automatic feedback hydraulic device and a trencher, the hydraulic device comprises a reversing valve, a first one-way balance valve, a second one-way balance valve, an energy accumulator and a hydraulic control switch valve, the oil inlet of the first one-way balance valve and the oil inlet of the second one-way balance valve are respectively communicated with the reversing valve behind the reversing valve; the front portion of the reversing valve is used for being communicated with an external hydraulic power source and an oil tank, an oil outlet of the first one-way balance valve is used for being communicated with a first cavity of an execution element, and an oil outlet of the second one-way balance valve is used for being communicated with a second cavity of the execution element. The reciprocating action of the actuating element action piece can be realized through the oil inlet and outlet matching of the first chamber and the second chamber; the energy accumulator is communicated with the hydraulic control switch valve, an external connecting port of the cut-off end of the hydraulic control switch valve is connected between the reversing valve and the first one-way balance valve, and the communicating end of the hydraulic control switch valve is used for being communicated with the first cavity. According to the utility model, the action piece acts reversely under the action of the external load force, and when the external load force is reduced, the action piece can automatically act forwards to return to the original position.

Description

Technical Field

[0001] The utility model relates to the technical field of engineering mechanical devices, in particular to an automatic load feedback hydraulic device and a trenching machine. Background Art

[0002] In mechanical equipment that requires reciprocating motion, a hydraulic drive circuit is usually used, and a reversing valve is set in the hydraulic drive circuit to achieve this. However, this setting usually requires manual adjustment during reversing. In this way, after the reciprocating motion parts perform forward motion, if they are subjected to load force under certain working conditions and move in the reverse direction, when the load force decreases or disappears and needs to move forward or reset as soon as possible, they need to wait for manual reversal before they can switch to forward motion, and they cannot react immediately, thus affecting the overall quality and efficiency of the operation. For example:

[0003] The underwater cable-laying trencher lowers its cable press and the left and right ejection knives and the whole machine moves forward during operation. Occasionally, the ejection knives and cable presser are subjected to load force due to underwater stones and other conditions, causing their cylinders to retract and stop in the retracted position. The reversing valve needs to be manually opened to lower the ejection knives to the same depth. During this process, the trencher keeps moving forward, resulting in poor ditching quality. Utility Model Content

[0004] In view of this, the purpose of the utility model is to provide a load automatic feedback hydraulic device and a trencher to solve the problem that after the actuating parts performing reciprocating motion move forward, if they are subjected to load force under some working conditions and move in the reverse direction, when the load force becomes smaller or disappears and needs to move forward as soon as possible, they need to wait for manual operation to reverse before they can switch to forward motion, and they cannot react in the first time, thus affecting the overall quality and efficiency of the operation.

[0005] In order to solve the above technical problems, the technical solution used in the utility model is:

[0006] The utility model discloses a load automatic feedback hydraulic device, comprising a reversing valve having at least left position, middle position and right position functions, a first one-way balancing valve, a second one-way balancing valve, an accumulator and a hydraulically controlled switch valve, wherein the oil inlets of the first one-way balancing valve and the second one-way balancing valve are respectively connected with the reversing valve after the reversing valve, and the reversing valve is used to communicate with an external hydraulic power source and an oil tank before the reversing valve, the oil outlet of the first one-way balancing valve is used to communicate with a first chamber of an actuator, and the oil outlet of the second one-way balancing valve is used to communicate with a second chamber of the actuator, and the reciprocating action of the actuating member of the actuator can be realized by the cooperation of the inlet and outlet oil of the first chamber and the second chamber;

[0007] The accumulator is communicated with the hydraulically controlled switch valve, and the external connection port of the cutoff end of the hydraulically controlled switch valve is connected between the reversing valve and the first one-way balancing valve, and the communication end of the hydraulically controlled switch valve is used to communicate with the first chamber.

[0008] Preferably, it further comprises a first overflow valve, one end of which is connected to the connecting end of the hydraulically controlled switch valve, and the other end of which is used to connect to the oil tank.

[0009] Further preferably, it also includes a first one-way valve, the oil inlet of the first one-way valve is connected to the oil outlet of the first overflow valve, and the oil outlet of the first one-way valve is connected to the connecting pipeline between the reversing valve and the oil inlet of the second one-way balancing valve.

[0010] Preferably, the external control port of the first one-way balancing valve is connected between the reversing valve and the second one-way balancing valve, and the external control port of the second one-way balancing valve is connected between the first one-way balancing valve and the first chamber.

[0011] Preferably, the actuator is a hydraulic cylinder, the first chamber is a rodless chamber, and the second chamber is a rod chamber.

[0012] Preferably, when the reversing valve is in the first state, the oil inlet of the first one-way balancing valve is connected to the hydraulic power source, the oil inlet of the second one-way balancing valve is connected to the oil tank, and after the external hydraulic power source is started, the actuator performs forward action.

[0013] Further preferably, when the reversing valve is in the second state, the oil inlet of the first one-way balancing valve is disconnected from the hydraulic power source, and the oil inlets of the first one-way balancing valve and the second one-way balancing valve are both connected to the oil tank.

[0014] Further preferably, when the reversing valve is in the third state, the oil inlet of the second one-way balancing valve is connected to the hydraulic power source, the oil inlet of the first one-way balancing valve is connected to the oil tank, and after the external hydraulic power source is started, the actuator performs a reverse action; the reversing valve can be converted from the first state or the second state to the third state.

[0015] Another object of the utility model is to provide a trencher, including a control system, a cable press and / or a punching knife, and also including the aforementioned load automatic feedback hydraulic device, the cable press and / or the punching knife are connected to the actuating part of the actuator, the actuator is a hydraulic cylinder, and the control system is connected to the reversing valve of the hydraulic device.

[0016] Compared with the prior art, the beneficial effects of the load automatic feedback hydraulic device described in the utility model are mainly reflected in:

[0017] The utility model controls the switching action of the reversing valve, on the one hand, the oil inlet of the first one-way balancing valve can be connected to the hydraulic power source, and the oil inlet of the second one-way balancing valve can be connected to the oil tank, and then under the drive of the hydraulic power source, the actuating member of the actuator can be moved forward; on the other hand, the oil inlet of the second one-way balancing valve can be connected to the hydraulic power source, and the oil inlet of the first one-way balancing valve can be connected to the oil tank, and then under the drive of the hydraulic power source, the actuating member of the actuator can be moved in the reverse direction, thereby realizing the reciprocating action of the actuating member of the actuator;

[0018] In addition, by providing the accumulator and the hydraulically controlled switch valve, and connecting the external connection port of the cut-off end of the hydraulically controlled switch valve between the reversing valve and the first one-way balancing valve, the communication end of the hydraulically controlled switch valve is used to communicate with the first chamber. After the positive action of the actuator is completed, the oil inlet of the first one-way balancing valve can be disconnected from the hydraulic power source by controlling the reversing valve, and the oil inlets of the first one-way balancing valve and the second one-way balancing valve can be connected to the oil tank. Therefore, when the actuating part of the actuator is subjected to an external load force and reversely acts, the accumulator can be pressed by the hydraulic oil from the first chamber, and when the external When the load force decreases, the accumulator can immediately release pressure to the first chamber, so that the actuating member can automatically move forward and return to its original position. In this way, the accumulator can repeatedly pressurize and release pressure as the actuating member is subjected to the external load force, effectively reducing the pressure fluctuation amplitude of the rear-valve circuit of each one-way balancing valve caused by the load force fluctuation, ensuring that the actuating member can automatically move forward and return to its original position after the external load force is reduced and disappears, increasing the instantaneous pressure of the oil leakage circuit, improving the automation degree and action efficiency of the hydraulic device, and this method of temporarily storing energy in the accumulator can save the power loss of the reversing valve when the actuating member moves in the reverse direction, and has energy-saving effect.

[0019] Compared with the prior art, the beneficial effects of the trenching machine described in the utility model are mainly reflected in:

[0020] After the cable press and / or left and right ejection knives in the trencher of this embodiment are lowered, during the forward movement of the trencher, the ejection knives and / or cable press are occasionally subjected to load force due to large rocks at the bottom of the seabed, causing the hydraulic cylinder to retract. After the load force becomes smaller or disappears after the rocks are crossed, the ejection knives and / or cable press can be automatically extended without waiting for manual control to extend them, thereby improving the gullying operation efficiency and the consistency and stability of the gullying depth, improving and enhancing the operation quality, and avoiding the problem of poor gullying quality caused by the ejection knife stopping in the retracted position and waiting for manual adjustment of the reversing valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other purposes, features and advantages of the present invention will become more apparent through a more specific description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals in all the accompanying drawings indicate the same parts, and the drawings are not intentionally scaled to the actual size, but the focus is on illustrating the subject matter of the present invention.

[0022] Figure 1 A schematic diagram of the principle of a load automatic feedback hydraulic device provided by an embodiment of the utility model;

[0023] Description of the drawings: reversing valve 1, first one-way balancing valve 2, second one-way balancing valve 3, accumulator 4, hydraulically controlled switch valve 5, hydraulic power source 6, oil tank 7, actuator 8, first chamber 9, second chamber 10, first overflow valve 11, first one-way valve 12. DETAILED DESCRIPTION

[0024] The technical scheme of the utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the utility model and implement it, but the examples given are not intended to limit the utility model. In the present embodiments, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the utility model, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the utility model.

[0025] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element and integrated therewith, or there may be an intermediate element at the same time. The terms "installed", "one end", "the other end" and similar expressions used in this utility model are for illustrative purposes only.

[0026] This embodiment provides a load automatic feedback hydraulic device, such as Figure 1As shown, it includes a reversing valve 1 having at least left position, middle position and right position functions, a first one-way balancing valve 2, a second one-way balancing valve 3, an accumulator 4 and a hydraulically controlled switch valve 5. The oil inlets of the first one-way balancing valve 2 and the second one-way balancing valve 3 are respectively connected with the reversing valve 1 after the reversing valve 1, and the reversing valve 1 is used to communicate with an external hydraulic power source 6 (not shown in the figure) and an oil tank 7 (not shown in the figure) before the reversing valve 1. The oil outlet of the first one-way balancing valve 2 is used to communicate with a first chamber 9 of an actuator 8, and the oil outlet of the second one-way balancing valve 3 is used to communicate with a second chamber 10 of the actuator 8. The reciprocating action of the actuating member of the actuator 8 can be realized by the cooperation of the inlet and outlet oil of the first chamber 9 and the second chamber 10.

[0027] The accumulator 4 is connected to the hydraulically controlled switch valve 5 , and the external connection port of the cutoff end of the hydraulically controlled switch valve 5 is connected between the reversing valve 1 and the first one-way balancing valve 2 , and the connecting end of the hydraulically controlled switch valve 5 is used to communicate with the first chamber 9 .

[0028] It should be noted that the first one-way balancing valve 2 and the second one-way balancing valve 3 are both combined functional valve body units including one-way valve functions and overflow valve functions. In a specific embodiment, they can be conventional one-way balancing valves including a one-way valve and an overflow valve, wherein the one-way valve is used to connect to an external hydraulic power source 6, and the overflow valve is used to connect to a return oil circuit. The external control port of the first one-way balancing valve 2 is connected between the reversing valve 1 and the second one-way balancing valve 3. When the second chamber 10 is filled with oil, part of the hydraulic oil can enter the overflow valve cavity of the first one-way balancing valve 2 through the external control port, which can greatly reduce the opening pressure of the overflow valve and make it easier for the hydraulic oil leaked back from the first chamber 9 to form a reflux, thereby improving the response sensitivity of the circuit and protecting the safety of the oil circuit components from being damaged by excessive pressure. Similarly, the external control port of the second one-way balancing valve 3 is connected between the first one-way balancing valve 2 and the first chamber 9. When the first chamber 9 is filled with oil, part of the hydraulic oil can enter the overflow valve cavity of the second one-way balancing valve 3 through the external control port, which can greatly reduce the opening pressure of the overflow valve and make it easier for the hydraulic oil leaked back from the second chamber 10 to form a reflux.

[0029] The utility model controls the switching action of the reversing valve 1. On the one hand, the oil inlet of the first one-way balancing valve 2 can be connected to the hydraulic power source 6, and the oil inlet of the second one-way balancing valve 3 can be connected to the oil tank 7, and then under the drive of the hydraulic power source 6, the actuating member of the actuator 8 can be made to move forward; on the other hand, the oil inlet of the second one-way balancing valve 3 can be connected to the hydraulic power source 6, and the oil inlet of the first one-way balancing valve 2 can be connected to the oil tank 7, and then under the drive of the hydraulic power source 6, the actuating member of the actuator 8 can be made to move in the reverse direction, thereby realizing the reciprocating action of the actuating member of the actuator 8;

[0030] In addition, by providing the accumulator 4 and the hydraulically controlled switch valve 5, and connecting the external connection port of the cut-off end of the hydraulically controlled switch valve 5 between the reversing valve 1 and the first one-way balancing valve 2, the connecting end of the hydraulically controlled switch valve 5 is used to communicate with the first chamber 9. After the positive action of the actuator 8 is completed, the oil inlet of the first one-way balancing valve 2 can be disconnected from the hydraulic power source 6 by controlling the reversing valve 1, and the oil inlets of the first one-way balancing valve 2 and the second one-way balancing valve 3 are connected to the oil tank 7. Therefore, when the actuating part of the actuator 8 is subjected to the external load force and reverses, the accumulator 4 can be punched by the hydraulic oil from the first chamber 9, and when the external load In the process of force decreasing, the accumulator 4 can immediately release pressure to the first chamber 9, so that the actuating member can automatically move forward and return to its original position. In this way, the accumulator 4 can be repeatedly pressed and depressurized as the actuating member is subjected to external load force, effectively reducing the pressure fluctuation amplitude of the rear circuit of each one-way balancing valve caused by load force fluctuation, ensuring that the actuating member can automatically move forward and return to its original position after the external load force is reduced or disappears, increasing the instantaneous pressure of the oil leakage circuit, improving the automation degree and action efficiency of the hydraulic device, and this method of temporarily storing energy in the accumulator 4 can save the power loss of the reversing valve 1 when the actuating member moves in the reverse direction, and has energy-saving effect.

[0031] In order to ensure the smoothness of the pressure relief process of the accumulator 4 and ensure that the actuating member automatically moves forward to reset, that is, returns to the state before being subjected to external load, preferably, the minimum pressure of the accumulator 4 is not less than the opening pressure corresponding to the pilot ratio of the second one-way balancing valve 3, so as to ensure that during the pressure relief process of the accumulator 4, the overflow valve in the second one-way balancing valve 3 is always in an open state, and the hydraulic oil in the second chamber 10 is always allowed to flow back smoothly with the forward movement of the actuating member, so that the actuating member can automatically move forward to reset. The above-mentioned pilot ratio is the pilot ratio of the balancing valve in the field of this technology, which refers to the ratio of the pilot area to the overflow area, or is equal to the ratio of the pressure required to open the balancing valve when there is no pilot oil to the pressure of the pilot oil alone to open it.

[0032] Preferably, it also includes a first overflow valve 11, one end of which is connected to the connecting end of the hydraulic switch valve 5, and the other end is used to connect to the oil tank 7. In this way, when the accumulator 4 is punched, excessive hydraulic oil can flow to the oil tank 7 through the first overflow valve 11, which can prevent the accumulator 4 from increasing the risk of damage due to excessive pressure, thereby improving the safety and reliability of the device. Further, it also includes a first check valve 12, the oil inlet of the first check valve 12 is connected to the oil outlet of the first overflow valve 11, and the oil outlet of the first check valve 12 is connected to the connecting pipeline between the reversing valve 1 and the oil inlet of the second one-way balancing valve 3, so that when the first overflow valve 11 is opened, the hydraulic oil passing through can be transported to the oil inlet of the second one-way balancing valve 3, thereby accelerating the rate of filling the second cavity with oil, avoiding the possibility of suction when subjected to a large instantaneous load, preventing suction of negative load, and improving the safety and reliability of the oil circuit.

[0033] The actuator 8 in the above embodiment can be a mechanism that can reciprocate, such as a cylinder or a motor. Taking the actuator 8 as a hydraulic cylinder as an example, the first chamber 9 is a rodless chamber, and the second chamber 10 is a rod chamber. After the piston rod in this embodiment is extended, if it is retracted by an external load force, it can be automatically extended and reset when the load force becomes smaller or disappears, without adjusting the reversing valve 1 to reset it. This not only improves the adaptability of the hydraulic device to the external complex environment, but also greatly reduces the workload of manual adjustment of the staff and improves work efficiency. Obviously, other types of actuators 8 also have similar technical effects as mentioned above, which will not be described in detail one by one.

[0034] Preferably, when the reversing valve 1 is in the first state, the oil inlet of the first one-way balancing valve 2 is connected to the hydraulic power source 6, the oil inlet of the second one-way balancing valve 3 is connected to the oil tank 7, and after the external hydraulic power source 6 is started, the actuator 8 performs forward action.

[0035] Specifically, the first action instruction can be executed by controlling the reversing valve 1, connecting the oil inlet of the first one-way balancing valve 2 to the hydraulic power source 6, and connecting the oil inlet of the second one-way balancing valve 3 to the oil tank 7, and after the external hydraulic power source 6 is started, the actuator 8 performs a positive action; see Figure 1 , the first action instruction is to put the reversing valve 1 in the right position, so that port A is connected to port P, and port B is connected to port T. At this time, under the drive of the external hydraulic power source 6, the accumulator 4 will be in a closed state due to the hydraulic oil flowing from port K into the hydraulic switch valve 5, and the actuator 8 will perform a positive action;

[0036] Furthermore, when the reversing valve 1 is in the second state, the oil inlet of the first one-way balancing valve 2 is disconnected from the hydraulic power source 3 , and the oil inlets of the first one-way balancing valve 2 and the second one-way balancing valve 3 are both connected to the oil tank 7 .

[0037] In use, after the actuator 8 completes the forward action, the control reversing valve 1 executes the second action instruction, disconnects the oil inlet of the first one-way balancing valve 2 from the hydraulic power source 6, and connects the oil inlets of the first one-way balancing valve 2 and the second one-way balancing valve 3 to the oil tank 7; see Figure 1, the second action instruction is to make the reversing valve 1 in the middle position, so that both ports A and B can be connected to port T, and port P is disconnected. In this state, if the actuating part of the actuator 8 is subjected to an external load force and moves in the reverse direction, the hydraulic oil in the first chamber 9 will flow back, part of which will flow through the hydraulic switch valve 5 and enter the accumulator 4 to press the accumulator 4, and part of which will flow through the first one-way balance valve 2 and then merge into the oil tank 7; since the accumulator 4 always has a pressure relief pressure, when the external load force on the actuating part becomes smaller or disappears, the hydraulic oil in the accumulator 4 will automatically flow to the first chamber 9 with lower pressure to make the actuating part move forward, thereby completing the return; this is repeated, and the accumulator 4 will adaptively press and relieve pressure according to the external load on the actuating part of the actuator 8.

[0038] The hydraulic device of this embodiment can automatically move forward and return to its original position when the actuating part of the actuator 8 is subjected to an external load force and moves in the reverse direction, and when the external load force decreases or disappears, so that there is no need for manual control of its return, which greatly improves the efficiency of the return of the actuating part.

[0039] Furthermore, when there is no need to respond to changes in the working environment or the work is completed and the acting part needs to move in reverse, when the reversing valve is in the third state, the oil inlet of the second one-way balancing valve 3 is connected to the hydraulic power source 6, the oil inlet of the first one-way balancing valve 2 is connected to the oil tank 7, and after the external hydraulic power source 6 is started, the actuator 8 performs a reverse action; the reversing valve 1 can be converted from the first state or the second state to the third state.

[0040] In use, the third action instruction can be executed by controlling the reversing valve 1, connecting the oil inlet of the second one-way balancing valve 3 to the hydraulic power source 6, and connecting the oil inlet of the first one-way balancing valve 2 to the oil tank 7, and the actuator 8 performs a reverse action; see Figure 1 , the third action instruction is to make the reversing valve 1 in the left position, so that the B port can be connected to the P port, and the A port can be connected to the T port. At this time, under the drive of the external hydraulic power source 6, the hydraulic oil flows into the second chamber 10, and the first chamber 9 and the accumulator 4 are both depressurized to make the hydraulic oil flow back into the oil tank 7, and the actuator 8 performs a reverse action. This embodiment can control the reversing valve 1 to switch from the first action instruction or the second action instruction to execute the third action instruction, and the switching is convenient and fast.

[0041] A trencher is also provided, comprising a control system, a cable press and / or a punching knife, and the aforementioned load automatic feedback hydraulic device, the cable press and / or the punching knife are connected to the actuating part of the actuator 8, the actuator 8 is a hydraulic cylinder, and the control system is connected to the reversing valve of the hydraulic device.

[0042] After the cable press and / or the left and right ejection knives in the trencher of this embodiment are lowered, during the forward movement of the trencher, the ejection knives and / or the cable press are occasionally subjected to load force due to large rocks at the bottom of the seabed, causing the hydraulic cylinder to retract. After the load force becomes smaller or disappears after the rocks are crossed, the ejection knives and / or the cable press can be automatically extended without waiting for manual control to extend them, thereby improving the gullying operation efficiency and the consistency and stability of the gullying depth, improving and enhancing the operation quality, and avoiding the problem of the ejection knife stopping in the retracted position and waiting for manual adjustment of the reversing valve 1, resulting in poor gullying quality.

[0043] In this specification, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] In the description of this specification, the description with reference to the terms "preferred embodiment", "further embodiment", "other embodiments" or "specific example" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0045] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A load automatic feedback hydraulic device, characterized in that: It comprises a reversing valve having at least left position, middle position and right position functions, a first one-way balancing valve, a second one-way balancing valve, an accumulator and a hydraulically controlled switch valve, wherein the oil inlets of the first one-way balancing valve and the second one-way balancing valve are respectively connected with the reversing valve after the reversing valve, and the reversing valve before the reversing valve is used to communicate with an external hydraulic power source and an oil tank, the oil outlet of the first one-way balancing valve is used to communicate with a first chamber of an actuator, and the oil outlet of the second one-way balancing valve is used to communicate with a second chamber of the actuator, and the reciprocating action of the actuating member of the actuator can be realized by the cooperation of the oil inlet and outlet of the first chamber and the second chamber; The accumulator is communicated with the hydraulically controlled switch valve, and the external connection port of the cutoff end of the hydraulically controlled switch valve is connected between the reversing valve and the first one-way balancing valve, and the communication end of the hydraulically controlled switch valve is used to communicate with the first chamber.

2. The hydraulic device according to claim 1, characterized in that: It also includes a first overflow valve, one end of which is connected to the communication end of the hydraulically controlled switch valve, and the other end of which is used to communicate with the oil tank.

3. The hydraulic device according to claim 2, characterized in that: It also includes a first one-way valve, the oil inlet of the first one-way valve is connected to the oil outlet of the first overflow valve, and the oil outlet of the first one-way valve is connected to the connecting pipeline between the reversing valve and the oil inlet of the second one-way balancing valve.

4. The hydraulic device according to claim 1, characterized in that: The external control port of the first one-way balancing valve is connected between the reversing valve and the second one-way balancing valve, and the external control port of the second one-way balancing valve is connected between the first one-way balancing valve and the first chamber.

5. The hydraulic device according to claim 1, characterized in that: The actuator is a hydraulic cylinder, the first chamber is a rodless chamber, and the second chamber is a rod chamber.

6. The hydraulic device according to claim 1, characterized in that: When the reversing valve is in the first state, the oil inlet of the first one-way balancing valve is connected to the hydraulic power source, the oil inlet of the second one-way balancing valve is connected to the oil tank, and after the external hydraulic power source is started, the actuator performs forward action.

7. The hydraulic device according to claim 6, characterized in that: When the reversing valve is in the second state, the oil inlet of the first one-way balancing valve is disconnected from the hydraulic power source, and the oil inlets of the first one-way balancing valve and the second one-way balancing valve are both connected to the oil tank.

8. The hydraulic device according to claim 7, characterized in that: When the reversing valve is in the third state, the oil inlet of the second one-way balancing valve is connected to the hydraulic power source, the oil inlet of the first one-way balancing valve is connected to the oil tank, and after the external hydraulic power source is started, the actuator performs a reverse action; the reversing valve can be converted from the first state or the second state to the third state.

9. A trenching machine, comprising a control system, a cable press and / or a punching knife, characterized in that: It also includes a load automatic feedback hydraulic device as described in any one of claims 1 to 8, the cable press and / or the punching knife are connected to the actuating part of the actuator, the actuator is a hydraulic cylinder, and the control system is connected to the reversing valve of the hydraulic device.

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