Oil return type differential loop

Abstract

The utility model relates to the field of hydraulic cylinder control, in particular to an oil return type differential loop which comprises an oil cylinder, a first piston and a second piston, pistons are slidably connected to the interior of the oil cylinder, and the interior of the oil cylinder is divided into a rod cavity and a rodless cavity by the first piston; the oil tank is used for storing hydraulic oil; one end of the oil inlet pipeline is communicated with the rodless cavity, and the other end is communicated with the oil tank; one end of the oil outlet pipeline is communicated with the rod cavity, and the other end is communicated with the oil tank; the first reversing valve is respectively communicated with the oil inlet pipeline and the oil outlet pipeline and can change the flow direction of the hydraulic oil; one end of the oil return pipeline communicates with the oil outlet pipeline, the other end of the oil return pipeline communicates with the oil inlet pipeline, and the communication position is located between the first reversing valve and the oil cylinder; and the second reversing valve is communicated with the oil return pipeline and the oil outlet pipeline and can change the flow direction of the hydraulic oil. The hydraulic control system has the effect of reducing the loss of the first reversing valve.

Description

Technical Field

[0001] The present application relates to the field of hydraulic cylinder control, and in particular to an oil return type differential circuit. Background Art

[0002] The differential circuit is a hydraulic circuit used to further increase the forward speed of the hydraulic cylinder piston without using a large flow pump and various auxiliary components.

[0003] The differential circuit includes an oil tank, an oil pump, an oil cylinder, an oil inlet pipe, an oil outlet pipe, an oil return pipe and a first reversing valve. A rodless chamber and a rod chamber are provided in the oil cylinder. One end of the oil inlet pipe is connected with the rodless chamber, and the other end is connected with the rod chamber. The oil pump is installed on the oil inlet pipe and is used to transport the oil in the oil tank to the rod chamber. One end of the oil outlet pipe is connected with the rod chamber, and the other end is connected with the oil tank. The first reversing valve is respectively connected to the oil inlet pipe and the oil outlet pipe. One end of the oil return pipe is connected with the oil outlet pipe, and the other end is connected to the first reversing valve. A second reversing valve for controlling the opening and closing of the oil outlet pipe is installed on the oil outlet pipe.

[0004] During the oil return process, the hydraulic oil continuously flows from the oil outlet pipe into the oil return pipe and into the first reversing valve, and then flows back into the rodless chamber, increasing the oil pressure of the hydraulic oil in the rodless chamber, thereby increasing the forward speed of the hydraulic cylinder piston.

[0005] Since the hydraulic oil continuously flows from the oil return pipe into the first reversing valve, the hydraulic oil pressure in the first reversing valve continuously increases. During long-term use, there is a problem of increasing the wear of the first reversing valve and reducing the life of the first reversing valve. Utility Model Content

[0006] The purpose of the present application is to provide an oil return type differential circuit, which can reduce the loss of the first reversing valve.

[0007] In the first aspect, the present application provides an oil return type differential circuit adopting the following technical solution:

[0008] An oil return type differential circuit, comprising:

[0009] An oil cylinder, wherein a first piston is slidably connected inside the oil cylinder, and the first piston divides the inside of the oil cylinder into a rod chamber and a rodless chamber;

[0010] Oil tank, used to store hydraulic oil;

[0011] An oil inlet pipeline, one end of which is connected to the rodless chamber, and the other end of which is connected to the oil tank;

[0012] An oil outlet pipeline, one end of which is connected to the rod chamber, and the other end of which is connected to the oil tank;

[0013] A first reversing valve, which is connected to the oil inlet pipeline and the oil outlet pipeline respectively and can change the flow direction of the hydraulic oil;

[0014] An oil return pipeline, one end of which is connected to the oil outlet pipeline, and the other end of which is connected to the oil inlet pipeline, and the connecting point is located between the first reversing valve and the oil cylinder;

[0015] The second reversing valve is respectively connected with the oil return pipeline and the oil outlet pipeline and can change the flow direction of the hydraulic oil.

[0016] By adopting the above technical solution, by setting the connecting point between the return oil pipeline and the oil inlet pipeline between the first reversing valve and the oil cylinder, the return pressurized hydraulic oil no longer needs to pass through the first reversing valve, thereby reducing the loss of the first reversing valve.

[0017] Optionally, a first one-way valve for controlling the flow direction of hydraulic oil in the oil inlet pipeline is installed on the oil inlet pipeline.

[0018] By adopting the above technical solution, the first one-way valve allows the hydraulic oil to flow in one direction and blocks the oil flow in the other direction. This can prevent the hydraulic oil from flowing back when the system pressure drops, ensuring the safety of the system.

[0019] Optionally, a second one-way valve for controlling the flow direction of hydraulic oil in the oil return pipeline is installed on the oil return pipeline.

[0020] By adopting the above technical solution, the second one-way valve allows the hydraulic oil to flow in one direction and blocks the oil flow in the other direction. This can prevent the hydraulic oil from flowing back when the system pressure drops, ensuring the safety of the system.

[0021] Optionally, the oil inlet pipeline includes a first branch pipe and a second branch pipe, the first branch pipe is connected to the rodless chamber, and the second branch pipe is connected to the oil tank;

[0022] The oil outlet pipeline includes a third branch pipe and a fourth branch pipe, the third branch pipe is connected to the rod chamber, and the fourth branch pipe is connected to the oil tank;

[0023] The first reversing valve is respectively connected to the first branch pipe, the second branch pipe, the third branch pipe and the fourth branch pipe;

[0024] A hydraulically controlled one-way valve is installed on the first branch pipe to control the flow direction of the hydraulic oil in the first branch pipe, and the hydraulically controlled one-way valve is connected to the third branch pipe.

[0025] By adopting the above technical solution and setting a hydraulically controlled one-way valve, the backflow of the first branch pipe can be reduced when oil flows into the rodless chamber, and the one-way flow restriction of the hydraulically controlled one-way valve can be released when oil flows into the rod chamber.

[0026] Optionally, a shock-resistant pressure gauge is installed on the second branch pipe.

[0027] By adopting the above technical solution, a shock-resistant pressure gauge is arranged on the second branch pipe, which can detect the hydraulic oil pressure in the oil return type differential circuit in real time.

[0028] Optionally, it further includes a hydraulic control device, the hydraulic control device includes a cylinder, a second piston and a first elastic member, the second piston is slidably connected in the cylinder and divides the cylinder into a first cavity and a second cavity, the fourth branch pipe includes a first branch pipe and a second branch pipe, one end of the first branch pipe is connected to the first reversing valve, and the other end is connected to the first cavity, one end of the second branch pipe is connected to the oil tank and the other end is connected to the second cavity, and the oil return pipeline is connected to the first cavity;

[0029] The first elastic member is arranged in the second cavity, one end of the first elastic member acts on the second piston, and the other end of the first elastic member acts on the inner wall of the second cavity.

[0030] By adopting the above technical solution and setting up a hydraulic control device, when the second reversing valve is damaged and cannot be reversed and can only reflux, the hydraulic oil pressure continues to increase, pushing the second piston to slide, thereby connecting the first cavity with the second branch pipe, allowing the hydraulic oil to flow into the oil tank, thereby reducing the situation where the return oil type differential circuit is damaged due to the continuous increase of the hydraulic oil.

[0031] Optionally, a through hole is formed on the side wall of the cylinder, and the second branch pipe is connected to the cylinder through the through hole. A first damping strip is fixedly connected to the inner wall of the cylinder. When the through hole is completely within the first cavity, the first damping strip can abut against the second piston and limit the sliding speed of the second piston.

[0032] By adopting the above technical solution, by setting the first damping strip, the return speed of the second piston is controlled, so that the hydraulic oil can be continuously depressurized for a period of time, thereby reducing the continuous operation of the return oil differential circuit under high pressure environment, and further reducing the possibility of damage to the return oil differential circuit.

[0033] Optionally, a baffle plate for blocking the perforation is rotatably connected inside the perforation, a first slide groove is provided on the inner wall of the perforation, a latch is slidably connected in the first slide groove, an insertion hole is provided on the baffle plate, the latch can be inserted into the insertion hole, a second elastic member is provided in the first slide groove, one end of the second elastic member acts on the inner wall of the first slide groove, and the other end of the second elastic member acts on the latch;

[0034] A second slide groove is provided on the inner wall of the cylinder, the second slide groove is communicated with the first slide groove, a driving block is slidably connected in the second slide groove, one end of the driving block is inserted into the first slide groove and fixedly connected to the latch, and the other end of the driving block is inserted into the cylinder, and the sliding of the second piston can push the driving block to slide;

[0035] A second damping strip is fixedly connected to the inner wall of the second sliding groove for limiting the sliding speed of the driving block.

[0036] During the sliding process of the second piston, the perforation is gradually opened. The process of gradually opening the perforation will also cause a drop in pressure, which will cause the second piston to rebound, and thus fail to achieve the effect of rapid pressure relief. By adopting the above technical solution and setting a baffle, the second piston needs to be completely offset from the perforation first, so that the second branch pipe can be connected to the first cavity, so that the perforation can be directly and completely opened for rapid pressure relief.

[0037] Optionally, a connecting hole is formed in the inner bottom wall of the first sliding groove, and the connecting hole is connected to the cylinder.

[0038] By adopting the above technical solution and providing the connecting hole, the pressure increase of the hydraulic oil in the first slide groove during the movement of the bolt can be reduced, thereby reducing the situation in which the sliding of the bolt is affected.

[0039] In summary, the present application includes at least one of the following beneficial technical effects:

[0040] 1. By setting the connecting point between the return oil pipeline and the inlet oil pipeline between the first reversing valve and the oil cylinder, the return pressurized hydraulic oil does not need to pass through the first reversing valve, thereby reducing the loss of the first reversing valve;

[0041] 2. The first check valve allows the hydraulic oil to flow in one direction and blocks the oil flow in the other direction. This prevents the hydraulic oil from flowing back when the system pressure drops, ensuring the safety of the system;

[0042] 3. By setting up a hydraulic control device, when the second reversing valve is damaged and cannot be reversed and can only reflux, the hydraulic oil pressure continues to increase, pushing the second piston to slide, thereby connecting the first cavity with the second branch pipe, allowing the hydraulic oil to flow into the oil tank, thereby reducing the situation where the return oil type differential circuit is damaged due to the continuous increase of hydraulic oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the overall structure of an oil return type differential circuit in an embodiment of the present application.

[0044] Figure 2 It is a schematic diagram of the cross-sectional structure of the hydraulic control device in Example 2 of the present application.

[0045] Figure 3 yes Figure 2 A magnified schematic diagram of center A.

[0046] In the figure, 1, oil cylinder; 11, rodless chamber; 12, rod chamber; 13, first piston;

[0047] 2. Fuel tank;

[0048] 3. Oil inlet pipeline; 31. First branch pipe; 32. Second branch pipe; 33. First check valve; 34. Hydraulic control check valve;

[0049] 4, oil outlet pipeline; 41, third branch pipe; 44, fourth branch pipe; 441, first branch pipe; 442, second branch pipe;

[0050] 5. Oil return pipeline; 51. Second one-way valve;

[0051] 6. Plunger pump;

[0052] 7. The first reversing valve;

[0053] 8. Second reversing valve;

[0054] 9. Hydraulic control device; 91. Cylinder; 911. First cavity; 912. Second cavity; 913. Perforation; 914. First slide groove; 915. Second slide groove; 916. Second elastic member; 917. Connecting hole; 92. Second piston; 93. First elastic member; 94. Baffle; 941. Socket; 95. Latch; 96. Drive block. DETAILED DESCRIPTION

[0055] The following is combined with Figure 1 -Attached Figure 3 , further details of this application are given.

[0056] Embodiment 1:

[0057] An oil return type differential circuit, refer to Figure 1 , including an oil cylinder 1, an oil tank 2, an oil inlet pipe 3 and an oil outlet pipe 4. A first piston 13 is slidably connected in the oil cylinder 1. The first piston 13 divides the oil cylinder 1 into a rodless chamber 11 and a rod chamber 12. One end of the oil inlet pipe 3 is connected to the rodless chamber 11, and the other end is connected to the oil tank 2. One end of the oil outlet pipe 4 is connected to the rod chamber 12, and the other end is connected to the oil tank 2. In this embodiment, a plurality of oil cylinders 1 are provided, and the rodless chambers 11 of the plurality of oil cylinders 1 are connected in sequence, and the rod chambers 12 of the plurality of oil cylinders 1 are connected in sequence. The number of oil cylinders 1 is two, three or other numbers. A plunger pump 6 is installed on the oil inlet pipe 3. The plunger pump 6 transports the hydraulic oil in the oil tank 2 to the oil inlet pipe 3, and the hydraulic oil flows into the rodless chamber 11 through the oil inlet pipe 3. The hydraulic oil flowing into the rodless chamber 11 pushes the first piston 13 to slide.

[0058] A return oil type differential circuit also includes a first reversing valve 7, which is provided with four connecting ports, namely, port a, port b, port c and port d. The oil inlet pipeline 3 includes a first branch pipe 31 and a second branch pipe 32. One end of the first branch pipe 31 is connected to the rodless cavity 11, and the other end is connected to port a. One end of the second branch pipe 32 is connected to port b, and the other end is connected to the oil tank 2. The oil outlet pipeline 4 includes a third branch pipe 41 and a fourth branch pipe 44. One end of the third branch pipe 41 is connected to the rod cavity 12, and the other end is connected to port c. One end of the fourth branch pipe 44 is connected to port d, and the other end is connected to the oil tank 2. The first reversing valve 7 can connect port a with port b or port d, and connect port c with port b or port d by reversing.

[0059] During the operation of the oil return type differential circuit, the first reversing valve 7 is energized to connect port a with port b and port c with port d. At this time, the plunger pump 6 flows the hydraulic oil into the rodless chamber 11 through the oil inlet pipe 3, thereby pushing the first piston 13 to slide forward.

[0060] When the first piston 13 slides to a predetermined position, the first reversing valve 7 is switched to connect port a with port d, and port c with port b, so that the second branch pipe 32 is connected with the third branch pipe 41, and the first branch pipe 31 is connected with the fourth branch pipe 44, so that the hydraulic oil flows into the rod chamber 12 through the third branch pipe 41, thereby pushing the first piston 13 to slide in the opposite direction, and returning the hydraulic oil in the rodless chamber 11 to the oil tank 2 through the first branch pipe 31 and the fourth branch pipe 44.

[0061] A first one-way valve 33 is installed on the second branch pipe 32. The first one-way valve 33 limits the flow direction of the hydraulic oil in the second branch pipe 32 so that the hydraulic oil can only flow from the oil tank 2 to the first reversing valve 7, thereby reducing the reflux of the hydraulic oil.

[0062] A hydraulically controlled one-way valve 34 is installed on the first branch pipe 31, and the hydraulically controlled one-way valve 34 is connected to the third branch pipe 41. When port a is connected to port b and port c is connected to port d, the hydraulically controlled one-way valve 34 limits the flow direction of the hydraulic oil in the first branch pipe 31, so that the hydraulic oil can only flow to the rodless chamber 11. When port a is connected to port d and port c is connected to port b, the hydraulic oil flows from the third branch pipe 41 to the rod chamber 12, and flows into the hydraulically controlled one-way valve 34 through the third branch pipe 41, thereby releasing the one-way conduction restriction of the hydraulically controlled one-way valve 34, so that the hydraulic oil in the rodless chamber 11 flows from the first branch pipe 31 to the fourth branch pipe 44, thereby realizing the reflux of the hydraulic oil.

[0063] An oil return type differential circuit also includes an oil return pipe 5, one end of which is connected to the oil outlet pipe 4, and the other end of which is connected to the first branch pipe 31, that is, connected to the oil inlet pipe 3. A hydraulic control device 9 is provided between the oil return pipe 5 and the oil outlet pipe 4. In this embodiment, the hydraulic control device 9 is a second reversing valve 8. The fourth branch pipe 44 includes a first branch pipe 441 and a second branch pipe 442. One end of the first branch pipe 441 is connected to the d port, and the other end of the first branch pipe 441 is connected to the second reversing valve 8. One end of the second branch pipe 442 is connected to the second reversing valve 8, and the other end is connected to the oil tank 2. One end of the oil return pipe 5 is connected to the first branch pipe 31, and the other end is connected to the second reversing valve 8.

[0064] When returning oil, the second reversing valve 8 controls the first branch pipe 441 to communicate with the oil return pipe 5, so that the hydraulic oil flows back into the first branch pipe 31, thereby pressurizing the hydraulic oil in the rodless chamber 11, thereby increasing the sliding speed of the first piston 13.

[0065] When the first reversing valve 7 is switched, the second reversing valve 8 is also switched. At this time, port a is connected to port d, port b is connected to port c, the first branch pipe 441 is connected to the second branch pipe 442, and the hydraulic oil in the rodless chamber 11 flows into the oil tank 2 through the first branch pipe 31, the first branch pipe 441 and the second branch pipe 442 for recovery.

[0066] A second one-way valve 51 is installed on the oil return pipeline 5. The second one-way valve 51 limits the flow direction of the hydraulic oil in the oil return pipeline 5, thereby reducing the occurrence of hydraulic oil backflow.

[0067] The second branch pipe 32 is connected to the second branch pipe 442, and an overflow valve is arranged between the second branch pipe 32 and the second branch pipe 442. A shockproof pressure gauge is installed on the second branch pipe 32. A liquid level and temperature gauge and a liquid level relay are installed in the oil tank 2.

[0068] The implementation principle of the embodiment of the present application is as follows: the plunger pump 6 is started to drive the hydraulic oil to flow to the rodless chamber 11, and during the sliding process of the first piston 13, the hydraulic oil in the rod chamber 12 is pushed into the third branch pipe 41, and flows into the rodless chamber 11 through the fourth branch pipe 44 and the oil return pipe 5, thereby increasing the movement speed of the first piston 13;

[0069] When the first piston 13 moves to the specified position, the first reversing valve 7 and the second reversing valve 8 are switched. At this time, the hydraulic oil flows from the second branch pipe 32 into the third branch pipe 41, and then into the rod chamber 12, so as to push the first piston 13 to move, and push the hydraulic oil in the rodless chamber 11 into the first branch pipe 31, and flow into the oil tank 2 through the first branch pipe 441 and the second branch pipe 442 for recovery.

[0070] Embodiment 2:

[0071] The structure of the present embodiment 2 is substantially the same as that of the embodiment 1, except that a hydraulic control device 9 is additionally provided.

[0072] Reference Figure 2 and Figure 3 The hydraulic control device 9 includes a cylinder 91, a second piston 92 and a first elastic member 93. The second piston 92 is slidably connected in the cylinder 91 and divides the cylinder 91 into a first cavity 911 and a second cavity 912. The first cavity 911 is connected to the first branch pipe 441 and the oil return pipe 5. A through hole 913 is opened on the side wall of the cylinder 91. The second branch pipe 442 is connected to the second cavity 912 through the through hole 913. The second piston 92 can slide to the second branch pipe 442 to connect with the first cavity 911.

[0073] The first elastic member 93 is disposed in the second cavity 912, one end of the first elastic member 93 acts on the second piston 92, and the other end of the first elastic member 93 acts on the inner wall of the second cavity 912. During the sliding process of the second piston 92, the first elastic member 93 is compressed. In this embodiment, the first elastic member 93 is a spring, and in other embodiments, the first elastic member 93 can also be a rubber pad or other elastically deformable objects.

[0074] When the second reversing valve 8 is damaged and cannot be reversed, the hydraulic oil can only flow from the return oil pipe 5 into the first branch pipe 31. At this time, the pressure of the hydraulic oil continues to increase, and the hydraulic oil flowing into the cylinder 91 pushes the second piston 92 to move, so that the second branch pipe 442 is connected to the first cavity 911, so that the high-pressure hydraulic oil flows back from the second branch pipe 442 into the oil tank 2, protecting the entire return oil type differential circuit.

[0075] A baffle 94 for blocking the through hole 913 is rotatably connected inside the through hole 913, a first slide groove 914 is provided on the inner wall of the through hole 913, a latch 95 is slidably connected in the first slide groove 914, a plug hole 941 is provided on the baffle 94, the latch 95 can be inserted into the plug hole 941, a second elastic member 916 is provided in the first slide groove 914, one end of the second elastic member 916 acts on the inner wall of the first slide groove 914, and the other end of the second elastic member 916 acts on the latch 95; a second slide groove 915 is provided on the inner wall of the cylinder 91, the second slide groove 915 is communicated with the first slide groove 914, a driving block 96 is slidably connected in the second slide groove 915, one end of the driving block 96 is inserted into the first slide groove 914 and fixedly connected to the latch 95, the other end of the driving block 96 is inserted into the cylinder 91, and the sliding of the second piston 92 can push the driving block 96 to slide. In this embodiment, a torsion spring is provided between the baffle 94 and the inner wall of the through hole 913, one end of the torsion spring is fixedly connected to the inner wall of the through hole 913, and the other end of the torsion spring is fixedly connected to the baffle 94. The rotation of the baffle 94 drives the torsion spring to undergo elastic deformation.

[0076] In this embodiment, the second elastic member 916 is a spring. In other embodiments, the second elastic member 916 can also be a rubber pad or other elastically deformable items.

[0077] During the sliding of the second piston 92, the driving block 96 is driven to move, so that the driving block 96 drives the latch 95 to move, so that the latch 95 is disengaged from the socket 941, thereby releasing the limit on the baffle 94. At this time, the second piston 92 is completely offset from the through hole 913, and the high-pressure hydraulic oil pushes the baffle 94 to rotate, so that the second branch pipe 442 is connected with the first cavity 911, so that the high-pressure hydraulic oil flows back to the oil tank 2.

[0078] Furthermore, a first damping strip is fixedly connected to the inner wall of the cylinder 91. When the latch 95 and the insertion hole 941 are separated from each other, the second piston 92 abuts against the first damping strip, so that the first damping strip limits the sliding speed of the second piston 92, thereby controlling the reset speed of the second piston 92, and further controlling the connection time between the second branch pipe 442 and the first cavity 911, so as to achieve the effect of controlling the return oil volume, so that the hydraulic oil can be fully depressurized at this time.

[0079] Furthermore, a second damping bar is fixedly connected to the inside of the second slide groove 915. When the driving block 96 slides in the second slide groove 915, it contacts the second damping bar, so that the second damping bar limits the sliding speed of the driving block 96, ensuring that when the baffle 94 is reset, the driving block 96 can drive the pin 95 to slide into the socket 941.

[0080] Furthermore, a connecting hole 917 is formed in the inner bottom wall of the first slide groove 914 , and the connecting hole 917 is connected to the cylinder 91 , thereby reducing the increase in the hydraulic oil pressure in the first slide groove 914 .

[0081] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An oil return type differential circuit, characterized in that: include: An oil cylinder (1) is slidably connected to a first piston (13) inside, wherein the first piston (13) divides the inside of the oil cylinder (1) into a rod chamber (12) and a rodless chamber (11); An oil tank (2), used for storing hydraulic oil; An oil inlet pipeline (3), one end of which is in communication with the rodless chamber (11), and the other end of which is in communication with the oil tank (2); An oil outlet pipeline (4), one end of which is in communication with the rod chamber (12) and the other end of which is in communication with the oil tank (2); A first reversing valve (7) is connected to the oil inlet pipeline (3) and the oil outlet pipeline (4) respectively and is capable of changing the flow direction of the hydraulic oil; An oil return pipeline (5), one end of which is connected to the oil outlet pipeline (4), and the other end of which is connected to the oil inlet pipeline (3), and the connecting point is located between the first reversing valve (7) and the oil cylinder (1); The second reversing valve (8) is respectively connected to the oil return pipeline (5) and the oil outlet pipeline (4) and is capable of changing the flow direction of the hydraulic oil.

2. The oil return type differential circuit according to claim 1, characterized in that: The oil inlet pipeline (3) is provided with a first one-way valve (33) for controlling the flow direction of the hydraulic oil in the oil inlet pipeline (3).

3. The oil return type differential circuit according to claim 1, characterized in that: The oil return pipeline (5) is provided with a second one-way valve (51) for controlling the flow direction of the hydraulic oil in the oil return pipeline (5).

4. The oil return type differential circuit according to claim 1, characterized in that: The oil inlet pipeline (3) comprises a first branch pipe (31) and a second branch pipe (32), the first branch pipe (31) being in communication with the rodless chamber (11), and the second branch pipe (32) being in communication with the oil tank (2); The oil outlet pipeline (4) comprises a third branch pipe (41) and a fourth branch pipe (44), the third branch pipe (41) being in communication with the rod chamber (12), and the fourth branch pipe (44) being in communication with the oil tank (2); The first reversing valve (7) is respectively connected to the first branch pipe (31), the second branch pipe (32), the third branch pipe (41) and the fourth branch pipe (44); A hydraulically controlled one-way valve (34) is installed on the first branch pipe (31) for controlling the flow direction of the hydraulic oil in the first branch pipe (31), and the hydraulically controlled one-way valve (34) is connected to the third branch pipe (41).

5. The oil return type differential circuit according to claim 4, characterized in that: A shock-resistant pressure gauge is installed on the second branch pipe (32).

6. The oil return type differential circuit according to claim 4, characterized in that: The invention also comprises a hydraulic control device (9), the hydraulic control device (9) comprising a cylinder (91), a second piston (92) and a first elastic member (93), the second piston (92) being slidably connected in the cylinder (91) and dividing the cylinder (91) into a first cavity (911) and a second cavity (912), the fourth branch pipe (44) comprising a first branch pipe (441) and a second branch pipe (442), one end of the first branch pipe (441) being in communication with the first reversing valve (7) and the other end being in communication with the first cavity (911), the second branch pipe (442) having one end in communication with the oil tank (2) and the other end in communication with the second cavity (912), and the oil return pipe (5) being in communication with the first cavity (911); The first elastic member (93) is arranged in the second cavity (912); one end of the first elastic member (93) acts on the second piston (92); and the other end of the first elastic member (93) acts on the inner wall of the second cavity (912).

7. The oil return type differential circuit according to claim 6, characterized in that: A through hole (913) is formed on the side wall of the cylinder (91), and the second branch pipe (442) is connected to the cylinder (91) through the through hole (913). A first damping strip is fixedly connected to the inner wall of the cylinder (91). When the through hole (913) is completely within the first cavity (911), the first damping strip can abut against the second piston (92) and limit the sliding speed of the second piston (92).

8. The oil return type differential circuit according to claim 7, characterized in that: A baffle (94) for blocking the through hole (913) is rotatably connected inside the through hole (913), a first slide groove (914) is provided on the inner wall of the through hole (913), a latch (95) is slidably connected inside the first slide groove (914), an insertion hole (941) is provided on the baffle (94), the latch (95) can be inserted into the insertion hole (941), a second elastic member (916) is provided in the first slide groove (914), one end of the second elastic member (916) acts on the inner wall of the first slide groove (914), and the other end of the second elastic member (916) acts on the latch (95); The inner wall of the cylinder (91) is provided with a second slide groove (915), the second slide groove (915) is communicated with the first slide groove (914), a driving block (96) is slidably connected in the second slide groove (915), one end of the driving block (96) is inserted into the first slide groove (914) and fixedly connected to the latch (95), and the other end of the driving block (96) is inserted into the cylinder (91), and the sliding of the second piston (92) can push the driving block (96) to slide; A second damping strip is fixedly connected to the inner wall of the second sliding groove (915) for limiting the sliding speed of the driving block (96).

9. The oil return type differential circuit according to claim 8, characterized in that: A communicating hole (917) is provided on the inner bottom wall of the first sliding groove (914), and the communicating hole (917) is in communication with the cylinder (91).

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