A crawler tensioning system and a crawler vehicle

Abstract

The present invention relates to the technical field of crawler vehicles, and specifically discloses a crawler tensioning system and a crawler vehicle. The crawler tensioning system includes an oil cylinder, an oil inlet oil circuit, an accumulator, a first check valve, a second check valve, a pressure reducing valve, an oil drain oil circuit, and a control spool. The piston rod of the oil cylinder is connected to a bracket for installing a guide wheel. The oil inlet oil circuit supplies oil to the piston chamber. Along the flow direction of the oil, the first check valve, the accumulator, the second check valve, and the pressure reducing valve are sequentially arranged in the oil inlet oil circuit. The oil drain oil circuit communicates with the piston chamber and has an oil drain port communicating with the fuel tank. Only when the oil pressure of the hydraulic oil in the oil drain oil circuit is greater than the opening pressure of the control spool, the control spool is opened by the hydraulic oil under the action of the hydraulic oil, and the opening pressure of the control spool is proportional to the retraction stroke of the piston rod. Therefore, the control spool is easily flushed open by the oil pressure initially, but as the piston rod retracts, the opening pressure also becomes larger and larger, which can avoid the guide wheel moving to the leftmost side instantaneously.

Description

Technical Field

[0001] The present invention relates to the technical field of crawler vehicles, and in particular to a crawler tensioning system and a crawler vehicle. Background Art

[0002] Crawler walking machines have characteristics such as large traction force, low ground contact pressure, and strong climbing ability, and are widely used in the fields of construction machinery, mining machinery, construction machinery, etc., such as excavators, pile driving machinery, drills, pavers, bulldozers, etc. The crawler tensioning device has a great influence on the crawler walking performance. If the pre-tensioning force is too large, the crawler rigidity is too high, and the tensioning device cannot play a buffering role, which will increase the internal friction in the crawler walking machine, resulting in engine power loss and accelerated wear of the crawler. If the pre-tensioning force is too small, the crawler will be loose, prone to tooth skipping and vibration, and even derailment will occur, posing a danger.

[0003] Currently, crawler tensioning generally uses a hydraulic plunger cylinder tensioning device, such as Figure 1 shown. The pressure oil enters the accumulator 100 through the one-way valve via the P port, and enters the plunger cylinder 300 through the throttle port 500 and the one-way valve, pushing the piston rod of the plunger cylinder 300, and the piston rod then pushes the idler wheel to tension the crawler. When the crawler tensioning length reaches the required value, the P port stops pressurizing, and the accumulator 100 maintains at this pressure to keep the crawler continuously tensioned. When the machine is driving and encounters a potholed ground, an obstacle, or when moving forward, backward, or turning, the idler wheel will be pulled to the left by the crawler, pushing the piston rod of the plunger cylinder 300 to the left, and the piston rod squeezes the oil in the plunger cylinder 300 to generate pressure. When this pressure is higher than the sum of the set pressure of the relief valve 200 and the pre-charge pressure of the accumulator 100, the relief valve 200 opens, and the oil in the plunger cylinder 300 flows into the accumulator 100, and the idler wheel can then move to the left to play a buffering role. When the mechanical equipment returns to a flat ground, crosses the obstacle, and ends the turn, the accumulator 100 releases the original oil in the plunger cylinder 300 again, pushing the piston rod of the plunger cylinder 300 to the right, and then pushing the idler wheel to the right to re-tension the crawler. This hydraulic plunger cylinder tensioning device can automatically tension the crawler and compensate for the increase in the pitch of the crawler chain links due to wear. However, for the relief valve 200 of this hydraulic plunger cylinder tensioning device to open, the oil pressure needs to exceed the sum of the set pressure of the relief valve 200 and the pre-charge pressure of the accumulator 100. At this time, the force generated on the plunger cylinder 300 is basically the same as the force that retracts the idler wheel when the mechanical equipment is at its maximum traction force. In this way, when the mechanical equipment is driving, only under the maximum traction force state or under a very severe impact can the relief valve 200 open and the tensioning device can play a buffering role. This will result in the tensioning device being completely ineffective in the vast majority of working conditions, unable to buffer and protect the crawler, and making the crawler wear even faster. Summary of the Invention

[0004] The object of the present invention is to provide a crawler tensioning system and a crawler vehicle, so as to solve the problem in the prior art that the opening pressure of the accumulator is too high, resulting in the ineffectiveness of the tensioning device.

[0005] On the one hand, the present invention provides a crawler tensioning system, which includes:

[0006] An oil cylinder, the piston rod of the oil cylinder is connected to a bracket, and the bracket is used for installing a guide wheel;

[0007] An oil inlet oil path, connected to the piston chamber of the oil cylinder;

[0008] An accumulator, arranged in the oil inlet oil path;

[0009] A first one-way valve and a second one-way valve, both arranged in the oil inlet oil path, the first one-way valve and the second one-way valve are respectively located upstream and downstream of the accumulator, and both the first one-way valve and the second one-way valve are configured to only allow the oil to flow in the direction of the piston chamber;

[0010] A pressure reducing valve, arranged in the oil inlet oil path, the pressure reducing valve is located downstream of the accumulator and upstream of the second one-way valve;

[0011] An oil discharge oil path, communicating with the piston chamber, and the oil discharge oil path has an oil discharge port communicating with the oil tank;

[0012] A control valve core, used to open or close the oil discharge port, and only when the oil pressure of the hydraulic oil in the oil discharge oil path is greater than the opening pressure of the control valve core, the control valve core is opened by the hydraulic oil under the action of the hydraulic oil, and the opening pressure of the control valve core is proportional to the retraction stroke of the piston rod.

[0013] As a preferred technical solution of the crawler tensioning system, the crawler tensioning system further includes:

[0014] A boosting assembly, capable of moving relative to the control valve core;

[0015] A first spring, with both ends respectively abutted against the boosting assembly and the control valve core, and the first spring is always in a compressed state;

[0016] A linkage rod, connecting the piston rod of the oil cylinder and the boosting assembly, and when the piston rod retracts, the linkage rod drives the boosting assembly to squeeze the first spring.

[0017] As a preferred technical solution of the crawler tensioning system, the boosting assembly includes:

[0018] A valve housing, having a first accommodating cavity;

[0019] A first valve rod, slidably arranged in the first accommodating cavity;

[0020] A second valve stem, threadedly connected to the first valve stem, and the linkage rod is clamped by the first valve stem and the second valve stem;

[0021] A first plug, disposed on the second valve stem, and two ends of the first spring respectively abut against the first plug and the control valve core.

[0022] As a preferred technical solution of the crawler tensioning system, the first plug is threadedly connected to the second valve stem.

[0023] As a preferred technical solution of the crawler tensioning system, the valve housing further has a second accommodation cavity communicating with the first accommodation cavity, and an inner diameter of the second accommodation cavity is smaller than an inner diameter of the first accommodation cavity;

[0024] The crawler tensioning system further includes a third valve stem slidably disposed in the second accommodation cavity and a valve body disposed on the valve housing. The third valve stem is located between the valve body and the control valve core. And when the control valve core closes the oil drain port, the first spring abuts the control valve core against the third valve stem. The third valve stem is slidably mated with the first valve stem, and the first valve stem can abut against the third valve stem and drive the third valve stem to synchronously move in a direction away from the valve body;

[0025] The valve body and the valve housing enclose a pressure oil cavity. The valve body is provided with a supplementary oil circuit and an oil return circuit both communicating with the pressure oil cavity. The crawler tensioning system further includes a supplementary oil check valve disposed in the supplementary oil circuit. The supplementary oil check valve is configured to only allow oil to flow from the fuel tank into the pressure oil cavity. The pressure oil cavity is configured to unload from the oil return circuit when the pressure of the hydraulic oil therein exceeds a set value, and the set value is greater than the maximum elastic force given by the first spring to the control valve core.

[0026] As a preferred technical solution of the crawler tensioning system, the oil drain circuit includes an oil inlet hole and an oil drain hole disposed on the valve housing, a first annular oil groove, a second annular oil groove and an oil drain cavity all disposed on the third valve stem, and a groove disposed on the third valve stem;

[0027] The oil inlet hole is respectively communicated with the piston cavity and the first annular oil groove. The first annular oil groove is always communicated with the oil drain cavity. The oil drain port is respectively communicated with the oil drain cavity and the groove. The groove is communicated with the second annular oil groove. The oil drain hole is respectively communicated with the second annular oil groove and the fuel tank. The control valve core is movably located in the groove.

[0028] As a preferred technical solution of the crawler tensioning system, the crawler tensioning system further includes a switching valve and a pressure detecting member disposed on the oil inlet circuit. The switching valve is located upstream of the first check valve, and the pressure detecting member is located between the first check valve and the pressure reducing valve and is configured to detect the oil pressure of the oil inlet circuit. When the oil pressure detected by the pressure detecting member exceeds a preset pressure, the switching valve closes.

[0029] As a preferred technical solution of the crawler tensioning system, the crawler tensioning system further includes a limiting baffle disposed between the cylinder block of the oil cylinder and the bracket. The limiting baffle can abut against the bracket to prevent the bracket from moving closer to the cylinder block.

[0030] As a preferred technical solution of the crawler tensioning system, the crawler tensioning system further includes a throttle valve disposed on the oil inlet circuit. The throttle valve is located downstream of the second check valve.

[0031] On the other hand, the present invention provides a crawler vehicle including the crawler tensioning system in any of the above solutions.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention provides a crawler tensioning system and a crawler vehicle. The crawler tensioning system includes an oil cylinder, an oil inlet circuit, an accumulator, a first check valve, a second check valve, a pressure reducing valve, an oil drain circuit, and a control valve core. The piston rod of the oil cylinder is connected to a bracket, and the bracket is used for mounting a guide wheel. The oil inlet circuit is connected to the piston chamber of the oil cylinder. Along the flow direction of the oil, the first check valve, the accumulator, the second check valve, and the pressure reducing valve are sequentially disposed on the oil inlet circuit, and both the first check valve and the second check valve are configured to only allow the oil to flow in the direction of the piston chamber. The oil drain circuit communicates with the piston chamber, and the oil drain circuit has an oil drain port communicating with the fuel tank. The control valve core is used to open or close the oil drain port, and only when the oil pressure of the hydraulic oil in the oil drain circuit is greater than the opening pressure of the control valve core, the control valve core is opened by the hydraulic oil under the action of the hydraulic oil. When the crawler encounters an obstacle, an uneven road surface, or turns, the crawler will push the guide wheel to compress the piston rod to retract. However, the opening pressure of the control valve core is proportional to the retraction stroke of the piston rod. Therefore, initially, the retraction stroke of the piston rod is small, and the control valve core is easily flushed open by the oil pressure. However, as the piston rod is continuously compressed, the retraction stroke of the piston rod becomes larger and larger, and the opening pressure of the control valve core is also larger, which can prevent the guide wheel from instantly moving to the leftmost side. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of a crawler tensioning system in the prior art;

[0035] Figure 2 is a schematic structural diagram of the crawler tensioning system in the embodiment of the present invention;

[0036] Figure 3 Partial structural schematic diagram of the crawler tensioning system in the embodiment of the present invention Figure 1 ;

[0037] Figure 4 Partial structural schematic diagram of the crawler tensioning system in the embodiment of the present invention Figure 2 。

[0038] In the figure:

[0039] 100, accumulator; 200, overflow valve; 300, plunger cylinder; 400, first one-way valve; 500, throttle port; 600, second one-way valve;

[0040] 1, cylinder; 101, piston rod; 102, piston chamber; 103, oil inlet; 104, annular oil groove;

[0041] 2, oil inlet pipeline; 3, accumulator; 4, first one-way valve; 5, second one-way valve; 6, pressure reducing valve; 7, oil drain port; 8, control valve core; 9, first spring; 10, linkage rod;

[0042] 11, valve housing; 1101, first accommodation chamber; 1102, second accommodation chamber; 1103, oil inlet hole; 1104, oil drain hole;

[0043] 12, first valve stem; 121, first chamber;

[0044] 13, second valve stem; 131, second chamber;

[0045] 14, first plug;

[0046] 15, third valve stem; 1501, first annular oil groove; 1502, second annular oil groove; 1503, oil drain chamber; 1504, groove;

[0047] 16, valve body; 1601, pressure oil chamber; 1602, oil replenishing pipeline; 1603, oil return pipeline; 1604, first communication pipeline; 1605, second communication pipeline;

[0048] 17, oil replenishing one-way valve;

[0049] 18, control valve; 1801, first valve ball; 1802, second spring; 1803, second plug;

[0050] 19. Nut; 20. Third plug; 21. Fourth plug; 22. Fifth plug; 23. Sixth plug; 24. Fuel tank; 25. First sealing ring; 26. Second sealing ring; 27. Third sealing ring; 28. Fourth sealing ring; 29. Dust seal; 30. Fifth sealing ring; 31. Sixth sealing ring; 32. Pressure detector; 33. Limit baffle; 35. Throttle valve; 36. Bracket; 37. Guide wheel. Detailed implementation manners

[0051] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0053] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0054] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0055] In the hydraulic plunger cylinder tensioning device in the prior art, the pressure oil enters the accumulator through the P port through the one-way valve, enters the plunger cylinder through the throttle port and the one-way valve, pushes the plunger cylinder piston rod, and the piston rod pushes the guide wheel to tension the track. The hydraulic plunger cylinder tensioning device can automatically tension the track and compensate for the increase in the track chain track pitch due to wear. However, the overflow valve of the hydraulic plunger cylinder tensioning device needs to open the oil pressure exceeding the set pressure of the overflow valve and the pre-charge pressure of the accumulator. At this time, the force generated on the plunger cylinder is basically the same as the force that retracts the guide wheel at the maximum traction of the mechanical equipment. In this way, when the mechanical equipment is driving, the overflow valve can only be opened under the maximum traction state or under a very serious impact, and the tensioning device can play a buffering role. This will cause the tensioning device to be completely ineffective under most working conditions and unable to play a buffering and protective role for the track, causing the track to wear more quickly.

[0056] In view of this, the present embodiment provides a track tensioning system to solve the above problem. The track tensioning system can be applied to tracked vehicles, such as tracked bulldozers and tracked loaders.

[0057] like Figures 2 to 4 As shown, the track tensioning system includes an oil cylinder 1, an oil inlet circuit 2, an accumulator 3, a first one-way valve 4, a second one-way valve 5, a pressure reducing valve 6, an oil drain circuit and a control valve core 8.

[0058] The oil cylinder 1 includes a cylinder body and a piston rod 101. The cylinder body is provided with a piston cavity 102. The piston rod 101 is slidably located in the piston cavity 102, and one end of the piston rod 101 extends out of the piston cavity 102 for connection with the bracket 36. The bracket 36 is used to install the guide wheel 37. Specifically, the cylinder body is provided with an oil inlet 103 connected to the piston cavity 102. The oil inlet oil circuit 2 is connected to the oil inlet 103 so that the high-pressure oil in the oil inlet oil circuit 2 can be delivered to the piston cavity 102 to push the piston rod 101 to extend. The oil cylinder 1 specifically adopts a single-acting oil cylinder, whose piston rod 101 is pushed out by oil pressure and retracted by external force. The oil inlet 103 is directly opposite to the piston rod 101. In order to prevent the piston rod 101 from blocking the oil inlet 103 and the oil from smoothly pushing the piston rod 101 to move, an annular oil groove 104 is also provided on the piston rod 101. When the piston rod 101 is in contact with the cylinder body, the annular oil groove 104 is connected to the oil inlet 103, and the hydraulic oil can enter the annular oil groove 104 through the oil inlet 103 and push the piston rod 101 to extend.

[0059] The accumulator 3, the first one-way valve 4, the second one-way valve 5, and the pressure reducing valve 6 are all arranged in the oil inlet circuit 2. Specifically, along the flow direction of the oil, the first one-way valve 4, the accumulator 3, the second one-way valve 5, and the pressure reducing valve 6 are arranged in sequence. Among them, both the first one-way valve 4 and the second one-way valve 5 are configured to only allow the oil to flow in the direction of the piston chamber 102. The oil in the accumulator 3 can be prevented from flowing back through the first one-way valve 4, and the oil in the piston chamber 102 can be prevented from flowing back to the accumulator 3 through the second one-way valve 5. Thus, the accumulator 3 is only used to supply oil to the piston chamber 102; the tension force of the oil cylinder 1 on the guide wheel 37 can be maintained through the accumulator 3; the upper limit of the oil pressure provided by the accumulator 3 to the piston chamber 102 can be adjusted through the pressure reducing valve 6, thereby ensuring the stability of the upper limit of the pressure of the oil flowing into the piston chamber 102; and when the guide wheel 37 becomes loose, the automatic extension of the piston rod 101 can be achieved through the cooperation of the accumulator 3 and the pressure reducing valve 6, and the automatic tensioning of the guide wheel 37 can be achieved.

[0060] The oil drain circuit is connected to the piston chamber 102. The oil drain circuit has an oil drain port 7 communicating with the fuel tank 24. The control valve core 8 is used to open or close the oil drain port 7. Specifically, when the oil pressure of the hydraulic oil in the oil drain circuit is greater than the opening pressure of the control valve core 8, the control valve core 8 can be driven to open the oil drain port 7 under the action of the oil pressure of the hydraulic oil. When the oil pressure of the hydraulic oil in the oil drain circuit is not greater than the opening pressure of the control valve core 8, the control valve core 8 closes the oil drain port 7 under the action of the opening pressure. Among them, the acting force of the hydraulic oil in the oil drain circuit on the control valve core 8 is opposite to the acting force of the opening pressure received by the control valve core 8. In this embodiment, the opening pressure of the control valve core 8 is proportional to the retraction stroke of the piston rod 101. The retraction stroke of the piston rod 101 refers to the dimension of the piston rod 101 moving into the piston chamber 102 under the action of the force given by the bracket 36. When the crawler vehicle is running, when the crawler encounters an obstacle, or an uneven road surface, or during steering, the crawler will push the guide wheel 37 to compress the piston rod 101 to retract (in the left direction as shown) Figure 1 However, since the opening pressure of the control valve core 8 is proportional to the retraction stroke of the piston rod 101, initially the retraction stroke of the piston rod 101 is small, and the control valve core 8 is easily flushed open by the oil pressure. But as the piston rod 101 is continuously compressed, the retraction stroke of the piston rod 101 becomes larger and larger, and the opening pressure of the control valve core 8 also becomes larger, which can prevent the guide wheel 37 from moving to the leftmost side instantaneously. The retraction stroke of the piston rod 101 refers to the stroke of the piston rod 101 being compressed into the piston chamber 102 by the guide wheel 37 under the action of an external force on the basis that the hydraulic oil in the piston chamber 102 drives the piston rod 101 to extend out of the piston chamber 102 and press the guide wheel 37 against the crawler.

[0061] To achieve that the opening pressure of the control valve core 8 can be adjusted proportionally with the retraction stroke of the piston rod 101, such as Figure 2 andFigure 4 As shown, in this embodiment, the crawler tensioning system further includes a boosting component, a first spring 9, and a linkage rod 10. Among them, the linkage rod 10 connects the piston rod 101 of the oil cylinder 1 and the boosting component. The two ends of the first spring 9 are respectively abutted against the boosting component and the control spool 8, and the first spring 9 is always in a compressed state, and the control spool 8 is given an opening pressure by the first spring 9. Specifically, the boosting component can move relative to the control spool 8. When the piston rod 101 extends and the linkage rod 10 drives the boosting component away from the control spool 8, the first spring 9 remains unchanged, and the opening pressure given by the first spring 9 to the control spool 8 remains unchanged; when the piston rod 101 retracts under the action force given by the bracket 36, the linkage rod 10 drives the boosting component to compress the first spring 9, the first spring 9 is gradually compressed, and the opening pressure given by the first spring 9 to the control spool 8 gradually increases.

[0062] In other embodiments, in order to achieve that the opening pressure of the control spool 8 can be adjusted proportionally with the retraction stroke of the piston rod 101, when the piston rod 101 extends, the displacement sensor can be used to collect in real time the displacement of the piston rod 101 moving into the piston chamber 102 due to the external force given by the bracket 36, and send the displacement to the controller. The controller queries the corresponding current from the pre-stored relationship diagram of displacement and current based on the displacement, and controls the electromagnet to work with this current. Among them, the displacement in the relationship diagram is proportional to the current, so that the opening pressure of the control spool 8 can be adjusted proportionally with the retraction stroke of the piston rod 101.

[0063] Among them, as Figure 2 and Figure 4 shown, the boosting component includes a valve housing 11, a first valve rod 12, a second valve rod 13, and a first plug 14. Among them, the valve housing 11 has a first accommodation cavity 1101; the first valve rod 12 is slidably arranged in the first accommodation cavity 1101; the second valve rod 13 is threadedly connected to the first valve rod 12, and the linkage rod 10 is clamped by the first valve rod 12 and the second valve rod 13. Specifically, the part of the second valve rod 13 located outside the first valve rod 12 forms a flange, and the outer diameter of the flange is equal to the outer diameter of the first valve rod 12, so that the linkage rod 10 can be clamped by the flange and the first valve rod 12. The first plug 14 is arranged on the second valve rod 13, and the two ends of the first spring 9 are respectively abutted against the first plug 14 and the control spool 8. By screwing the first valve rod 12, the position of the first plug 14 can be adjusted, which is convenient for adjusting the opening pressure given by the first spring 9 to the control spool 8 at the initial time.

[0064] As Figure 2 and Figure 4As shown, in this embodiment, a first cavity 121 is provided inside the first valve stem 12, a second cavity 131 is provided in the second valve stem 13, the second valve stem 13 communicates with the first cavity 121, the second valve stem 13 is screwed to the wall of the first cavity 121, the first plug 14 is screwed to the wall of the second cavity 131, the first cavity 121 and the second cavity 131 communicate, at least a part of the control valve core 8 is located in the first cavity 121, a part of the first spring 9 is located in the second cavity 131 and abuts against the first plug 14, and another part of the first spring 9 is located in the first cavity 121 and abuts against the control valve core 8. The stability of the direction of the first spring 9 during deformation can be ensured through the second cavity 131. Preferably, in order to ensure that the control valve core 8 can stably close the oil drain port 7, in this embodiment, the control valve core 8 has a protruding conical head. The conical head extends into the oil drain port 7 and closes the oil drain port 7 through the conical surface. The conical head can play a guiding role, and the sealing effect can be ensured to be stable through the line sealing method. Further preferably, the control valve core 8 further has a guiding column, and the first spring 9 is sleeved on the guiding column, which can further ensure the stability of the direction of the first spring 9 during deformation.

[0065] Optionally, the first plug 14 is threadedly connected to the second valve stem 13. In this way, by screwing the first plug 14, it is also convenient to adjust the opening pressure applied to the control valve core 8 by the first spring 9 initially, so that the force applied by the first spring 9 to the control valve core 8 initially has a larger adjustment range. Further preferably, a nut 19 is also screwed on the first plug 14. The nut 19 is located outside the valve housing 11. The nut 19 can abut against or separate from the second valve stem 13. When the nut 19 abuts tightly against the second valve stem 13, the position of the first plug 14 can be locked. When the nut 19 and the second valve stem 13 are separated, the first plug 14 can be screwed, and then the relative position of the first plug 14 and the second valve stem 13 can be adjusted to realize the adjustment of the compression degree of the first spring 9.

[0066] Optionally, as Figures 2 to 4As shown, the valve housing 11 is further provided with a second accommodation cavity 1102 communicating with the first accommodation cavity 1101, and the inner diameter of the second accommodation cavity 1102 is smaller than that of the first accommodation cavity 1101; the crawler belt tensioning system further includes a third valve rod 15 slidably disposed in the second accommodation cavity 1102 and a valve body 16 disposed on the valve housing 11. The third valve rod 15 is located between the valve body 16 and the control valve core 8. When the control valve core 8 closes the oil drain port 7, the first spring 9 presses the control valve core 8 against the third valve rod 15. The third valve rod 15 is slidably engaged with the first valve rod 12, and the first valve rod 12 can abut against the third valve rod 15 and drive the third valve rod 15 to move synchronously away from the valve body 16. Specifically, the valve body 16 is located on the left side of the third valve rod 15, and the third valve rod 15 can be limited on the left side by the valve body 16. The third valve rod 15 is located on the left side of the first valve rod 12. Driven by the first spring 9, the control valve core 8 can press against the third valve rod 15. Specifically, an opening is provided on the left side of the first cavity 121, and the diameter of the opening is smaller than the inner diameter of the first cavity 121. A flange protrudes from the right end of the third valve rod 15, and the flange is slidably located in the first cavity 121, and the side wall at the opening position can abut against the flange. Thus, when the piston rod 101 extends, the linkage rod 10 can drive the third valve rod 15 to move synchronously to the right through the first valve rod 12. And when the first valve rod 12 and the third valve rod 15 move synchronously to the right, under the action force provided by the first spring 9, the relative positions of the first valve rod 12 and the third valve rod 15 remain unchanged.

[0067] In this embodiment, the oil drain port 7 is arranged on the third valve stem 15. The valve body 16 and the valve housing 11 enclose a pressure oil chamber 1601. One end of the third valve stem 15 is located in the pressure oil chamber 1601. The valve body 16 is provided with a makeup oil passage 1602 and an oil return passage 1603 that are both communicated with the pressure oil chamber 1601. The crawler tensioning system further includes a makeup oil check valve 17 arranged in the makeup oil passage 1602. The makeup oil passage 1602 and the oil return passage 1603 are both communicated with the fuel tank 24. The makeup oil check valve 17 is configured to only allow the oil to flow from the fuel tank 24 into the pressure oil chamber 1601. The pressure oil chamber 1601 is configured to unload from the oil return passage 1603 when the pressure of the hydraulic oil therein exceeds a set value, and the set value is greater than the maximum elastic force given by the first spring 9 to the control spool 8. Specifically, when the linkage rod 10 drives the first valve stem 12 and the third valve stem 15 to move synchronously to the right, the volume of the pressure oil chamber 1601 increases and a negative pressure is generated. At this time, makeup oil can be supplied through the makeup oil check valve 17. When the crawler pushes the guide wheel 37 to compress the piston rod 101 and retract and move to the left, during the process of the first spring 9 being compressed, the oil pressure in the pressure oil chamber 1601 has not yet reached the set value. At this time, the position of the third valve stem 15 does not move, and the first valve stem 12 moves relatively to the left with respect to the third valve stem 15. If the impact force received by the guide wheel 37 is large enough, finally the second valve stem 13 will abut against the third valve stem 15. At this time, a part of the force acting on the piston rod 101 will be transmitted to the third valve stem 15 through the linkage rod 10, the first valve stem 12 and the second valve stem 13. If the sum of the force given by the first spring 9 to the third valve stem 15 and the force given by the second valve stem 13 is greater than the set value, it will cause the oil in the pressure oil chamber 1601 to be unloaded through the oil return passage 1603, and the first valve stem 12, the second valve stem 13 and the third valve stem 15 will move to the left synchronously.

[0068] It can be understood that as the usage time of the crawler increases, the chain pitch of the crawler becomes larger due to wear, which will cause the retraction stroke of the piston rod 101 to relatively increase. In this embodiment, with the cooperation of the accumulator 3 and the pressure reducing valve 6, the retraction stroke of the piston rod 101 can be automatically matched with the actual condition of the crawler. However, when the retraction stroke of the piston rod 101 increases, the driving stroke of the crawler on the guide wheel 37 may also increase, that is, when the piston rod 101 is compressed, the stroke may exceed the normal situation. At this time, the space of the pressure oil chamber 1601 can be compressed by the third valve stem 15 to make up for it.

[0069] Specifically, such as Figure 1As shown, in this embodiment, when the piston rod 101 abuts against the left side wall of the cylinder block of the oil cylinder 1, there is a gap L0 between the piston rod 101 and the bracket 36. When the piston rod 101 extends, it will first drive the first valve rod 12 to move synchronously for an idle stroke L0, and then it can push the bracket 36 and the guide wheel 37 back to their positions. When the crawler is not worn, the maximum distance that the crawler can push the guide wheel 37 to move is L1, that is, the maximum size that the first spring 9 can be compressed by the first plug 14 is L1, and L1 is less than the minimum distance at which the crawler becomes loose and skips teeth due to the leftward movement of the guide wheel 37. However, when the crawler becomes loose after long-term use, there may be a situation where the distance that the crawler pushes the guide wheel 37 to move leftward is greater than L1. When the first valve rod 12 moves a distance of L1 relative to the second valve rod 13, the second valve rod 13 will abut against the first valve rod 12 and move synchronously for the remaining distance. At this time, the pressure of the hydraulic oil in the pressure oil chamber 1601 will exceed the set value, and the space of the pressure oil chamber 1601 will gradually decrease. At the same time, the gap L0 can ensure that there is enough movement space for the piston rod 101.

[0070] Optionally, as Figure 1 shown, the crawler tensioning system further includes a limit baffle 33 arranged between the cylinder block of the oil cylinder 1 and the bracket 36. The limit baffle 33 can abut against the bracket 36 to prevent the bracket 36 from moving towards the cylinder block, can limit the extreme position of the guide wheel 37, and can protect the oil cylinder 1 at the same time.

[0071] In this embodiment, the valve body 16 and the valve housing 11 are connected by bolts. In order to prevent leakage in the pressure oil chamber 1601, in this embodiment, a first sealing ring 25 is further provided between the valve housing 11 and the valve body 16.

[0072] As Figure 2 and Figure 3As shown in the figure, in this embodiment, a control valve 18 is provided in the oil return circuit 1603. The control valve 18 is configured to open when the oil pressure in the pressure oil chamber 1601 exceeds a set value, and the set value is greater than the maximum elastic force given by the first spring 9 to the control valve core 8. Specifically, the control valve 18 includes a second spring 1802, a first valve ball 1801, and a second plug 1803 provided in the oil return circuit 1603. Among them, the oil return circuit 1603 is a stepped oil circuit. The first valve ball 1801 is located at the constriction of the stepped oil circuit. The second plug 1803 is used to block the first process hole of the oil return circuit 1603. The two ends of the second spring 1802 are respectively in contact with the second plug 1803 and the first valve ball 1801. The second spring 1802 is in a compressed state and is used to drive the first valve ball 1801 to block the oil return circuit 1603. When the oil pressure in the pressure oil chamber 1601 is greater than the set value, the force exerted on the first valve ball 1801 by the hydraulic oil will be greater than the force exerted on the first valve ball 1801 by the second spring 1802, and the first valve ball 1801 can be driven to open the oil return circuit 1603.

[0073] As Figure 2 and Figure 3 shown, in this embodiment, the valve body 16 is further provided with a first communication oil circuit 1604. The first communication oil circuit 1604 is used to connect the oil return circuit 1603 with the part of the oil replenishment circuit 1602 communicating with the fuel tank 24, and the second process hole of the first communication oil circuit 1604 is blocked by a third plug 20, so as to simplify the oil circuit structure. The valve body 16 is further provided with a second communication oil circuit 1605. Both the oil return circuit 1603 and the oil replenishment circuit 1602 are connected to the pressure oil chamber 1601 through the second communication oil circuit 1605, and the third process hole of the second communication oil circuit 1605 is blocked by a fourth plug 21.

[0074] Optionally, as Figure 2 and Figure 3 shown, the valve body 16 is further provided with a fifth plug 22. The fifth plug 22 is threadedly connected to the valve body 16. The fifth plug 22 is provided with a through hole, and the through hole connects the pressure oil chamber 1601 and the second communication oil circuit 1605. The third valve rod 15 is threadedly connected with a sixth plug 23. When the third valve rod 15 is in the initial position, the fifth plug 22 and the sixth plug 23 are in contact. Thus, the initial position of the third valve rod 15 can be adjusted by screwing the fifth plug 22 and the sixth plug 23.

[0075] As Figures 2 to 4As shown in the figure, in this embodiment, the oil drainage passage includes an oil inlet hole 1103 and an oil outlet hole 1104 provided on the valve housing 11, a first annular oil groove 1501, a second annular oil groove 1502 and an oil drainage cavity 1503 all provided on the third valve stem 15, and a groove 1504 provided on the third valve stem 15. The oil inlet hole 1103 is respectively communicated with the piston cavity 102 and the first annular oil groove 1501. The first annular oil groove 1501 is always communicated with the oil drainage cavity 1503. The oil drain port 7 is respectively communicated with the oil drainage cavity 1503 and the groove 1504. The groove 1504 is communicated with the second annular oil groove 1502. The oil outlet hole 1104 is respectively communicated with the second annular oil groove 1502 and the fuel tank 24. The control valve core 8 is movably located in the groove 1504. Among them, the first annular oil groove 1501 and the second annular oil groove 1502 are both arranged around the outer peripheral surface of the third valve stem 15, and the first annular oil groove 1501 and the second annular oil groove 1502 both extend along the axial direction of the third valve stem 15. When the third valve stem 15 is moving, the first annular oil groove 1501 can always be communicated with the oil inlet hole 1103, and the first annular oil groove 1501 can always be communicated with the oil drainage cavity 1503. The second annular oil groove 1502 can always be communicated with the oil outlet hole 1104, and the second annular oil groove 1502 can always be communicated with the groove 1504. Thus, when the control valve core 8 opens the oil drain port 7, the oil in the piston cavity 102 can sequentially flow back to the fuel tank 24 through the oil inlet hole 1103, the first annular oil groove 1501, the oil drainage cavity 1503, the oil drain port 7, the groove 1504, the second annular oil groove 1502 and the oil outlet hole 1104.

[0076] As Figure 1 shown in the figure, in this embodiment, when the third valve stem 15 is in the initial position, the fifth plug 22 and the sixth plug 23 are in contact. At this time, the right end of the first annular oil groove 1501 is communicated with the oil inlet hole 1103, the right end of the second annular oil groove 1502 is communicated with the oil inlet hole 1103. The distance between the left end of the first annular oil groove 1501 and the oil inlet hole 1103 is L2, and the distance between the left end of the second annular oil groove 1502 and the oil outlet hole 1104 is L3. In this embodiment, L2 is less than L3, and L2 is greater than the maximum retraction stroke of the piston rod 101. Thus, during the telescopic process of the piston rod 101, the oil inlet hole 1103 and the oil outlet hole 1104 will not be blocked.

[0077] In order to prevent the hydraulic oil in the pressure oil chamber 1601 from leaking into the first annular oil groove 1501, in this embodiment, a second sealing ring 26 is further provided between the third valve rod 15 and the valve housing 11. The second sealing ring 26 is located between the first annular oil groove 1501 and the pressure oil chamber 1601. In order to prevent the hydraulic oil in the first annular oil groove 1501 from leaking into the second annular oil groove 1502, a third sealing ring 27 is further provided between the third valve rod 15 and the valve housing 11. The third sealing ring 27 is located between the second annular oil groove 1502 and the first annular oil groove 1501.

[0078] In this embodiment, the groove 1504 communicates with the second chamber 131, and the second annular oil groove 1502 communicates with the second accommodating chamber 1102. In order to prevent the hydraulic oil in the second annular oil groove 1502 from leaking through the gap between the first valve rod 12 and the valve housing 11, a fourth sealing ring 28 is provided between the first valve rod 12 and the valve housing 11. The fourth sealing ring 28 is close to the left end of the first accommodating chamber 1101. In order to prevent external dust from entering between the first valve rod 12 and the valve housing 11, a dust-proof ring 29 is further provided between the first valve rod 12 and the valve housing 11. The dust-proof ring 29 is located on the left side of the fourth sealing ring 28 and at the left end of the first accommodating chamber 1101. In order to prevent the hydraulic oil in the groove 1504 from leaking between the second valve rod 13 and the first valve rod 12, a fifth sealing ring 30 is provided between the second valve rod 13 and the first valve rod 12. In order to prevent the hydraulic oil in the groove 1504 from leaking between the second valve rod 13 and the first plug 14, a sixth sealing ring 31 is provided between the second valve rod 13 and the first plug 14.

[0079] Optionally, as Figure 1 shown, the crawler tensioning system further includes a switching valve (not shown in the drawings) provided in the oil inlet circuit 2 and a pressure detecting member 32. The switching valve is located upstream of the first check valve 4, and the pressure detecting member 32 is located between the first check valve 4 and the pressure reducing valve 6 and is used to detect the oil pressure in the oil inlet circuit 2. When the oil pressure detected by the pressure detecting member 32 exceeds the preset pressure, the switching valve closes. The pressure reducing valve 6 is used to detect the oil pressure in the oil inlet circuit 2, that is, to detect the pressure of the oil in the accumulator 3. When the pressure of the oil in the accumulator 3 detected is less than the preset pressure, the pressure detecting member 32 sends a low-level signal to the controller, and the controller controls the switching valve to open to pressurize the accumulator 3 through the oil pump. When the pressure of the accumulator 3 reaches the preset pressure, the pressure detecting member 32 sends a high-level signal to the controller, and the controller can control the switching valve to close, and the oil pump can stop pressurizing the accumulator 3. Among them, the switching valve can be an electromagnetic switching valve, and the pressure detecting member 32 can be a pressure sensor.

[0080] Optionally, as Figure 1As shown, the crawler tensioning system further includes a throttle valve 35 disposed in the oil inlet circuit 2, and the throttle valve 35 is located downstream of the second one-way valve 5. When the hydraulic oil in the accumulator 3 is released, the throttle valve 35 can control the flow rate of the hydraulic oil to prevent the hydraulic oil from flowing into the piston chamber 102 of the oil cylinder 1 too quickly, which may cause violent impact and damage the crawler.

[0081] The working principle of this crawler tensioning system is as follows:

[0082] 1) When the crawler is not yet tensioned, the pressure of the hydraulic oil in the accumulator 3 is detected by the pressure detection member 32. When the detected pressure of the accumulator 3 is less than the preset pressure, the pressure detection member 32 sends a low-level signal to the controller, and the controller controls the opening of the switching valve to pressurize the accumulator 3 through the oil pump. When the detected pressure of the accumulator 3 reaches the preset pressure, the pressure detection member 32 sends a high-level signal to the controller, and the controller can control the closing of the switching valve, and the oil pump no longer pressurizes the accumulator 3. The hydraulic oil entering the accumulator 3 flows into the piston chamber 102 of the oil cylinder 1 successively through the pressure reducing valve 6, the second one-way valve 5, and the throttle valve 35, and at the same time enters the oil discharge chamber 1503 through the oil inlet hole 1103 and the first annular oil groove 1501. However, the oil pressure at the oil discharge port 7 is less than the opening pressure given by the first spring 9 to the control valve core 8 at this time, the control valve core 8 closes the oil discharge port 7, and the first spring 9 presses the third valve stem 15 against the first valve stem 12 through the control valve core 8. The hydraulic oil entering the piston chamber 102 pushes the piston rod 101 to move to the right, the piston rod 101 pushes the bracket 36 and drives the idler wheel 37 to move to the right as a whole, so that the idler wheel 37 tensions the crawler. At the same time, the piston rod 101 also drives the first valve stem 12 and the second valve stem 13 to move to the right as a whole through the linkage rod 10, and the first valve stem 12 also drives the third valve stem 15 to move to the right at the same time, and the moving distance of the third valve stem 15 is equal to the extending distance of the piston rod 101. The movement of the third valve stem 15 will cause the volume of the pressure oil chamber 1601 to increase and generate a negative pressure. Under the action of the negative pressure, the hydraulic oil in the fuel tank 24 enters the pressure oil chamber 1601 from the oil replenishing one-way valve 17 through the oil replenishing circuit 1602 to fill the pressure oil chamber 1601 with hydraulic oil. When the oil pressure in the piston chamber 102 reaches the upper limit oil pressure of the pressure reducing valve 6, the pressure reducing valve 6 closes, the piston rod 101 no longer extends, and at this time the idler wheel 37 tensions the crawler under the push of the piston rod 101.

[0083] 2) When the crawler vehicle encounters an obstacle, an uneven road surface, or turns during travel, the idler wheel 37 will be subjected to a leftward thrust from the crawler. This thrust is transmitted through the bracket 36 to the piston rod 101 to squeeze the hydraulic oil in the piston chamber 102. The oil pressure in the piston chamber 102 and the oil discharge chamber 1503 rises synchronously and equally. When the pressure of the hydraulic oil in the oil discharge chamber 1503 exceeds the opening pressure of the control valve core 8, the control valve core 8 is pushed open by the hydraulic oil to open the oil discharge port 7. The hydraulic oil in the oil discharge chamber 1503 flows through the oil discharge port 7, the groove 1504, the second annular oil groove 1502, and the oil discharge hole 1104 to drain into the fuel tank 24. Thus, the hydraulic oil in the piston chamber 102 can be reduced, and the piston rod 101 is pushed to move leftward. At the same time, the piston rod 101 drives the first valve rod 12 to move leftward synchronously through the linkage rod 10. However, since the oil pressure in the pressure oil chamber 1601 has not reached the set value, the position of the third valve rod 15 remains unchanged at this time. The first spring 9 is gradually compressed, and the second valve rod 13 gradually approaches the third valve rod 15. During this process, due to the compression of the first spring 9, the opening pressure of the control valve core 8 gradually increases, which can prevent the idler wheel 37 from being instantaneously pushed to the leftmost end. Among them, the position of the third valve rod 15 when the piston rod 101 stops moving is affected by the magnitude of the leftward thrust exerted by the crawler on the idler wheel 37, which is specifically divided into the following four different situations:

[0084] A. When the thrust is small, the second valve rod 13 has not yet abutted against the third valve rod 15. At this time, the opening pressure applied to the control valve core 8 by the first spring 9 is equal to the pressure of the hydraulic oil in the oil discharge chamber 1503.

[0085] B. When the thrust is large, the second valve rod 13 abuts against the third valve rod 15. At this time, the force exerted by the first spring 9 on the third valve rod 15 through the control valve core 8 reaches the maximum and is F1; the piston rod 101 will also transmit force to the third valve rod 15 through the linkage rod 10, the first valve rod 12, and the second valve rod 13, and this part of the force is F2; the third valve rod 15 squeezes the oil in the pressure oil chamber 1601 under the combined action of F1 and F2. If the oil pressure in the pressure oil chamber 1601 is less than the set value, the control valve 18 will not open, so the position of the third valve rod 15 remains unchanged.

[0086] C. When the thrust is very large, the resultant force of F1 and F2 will be greater than the maximum pressure exerted by the pressure oil chamber 1601 on the third valve stem 15. At this time, under the action of the resultant force of F1 and F2, the third valve stem 15 squeezes the pressure oil chamber 1601, and the oil pressure in the pressure oil chamber 1601 gradually increases and exceeds the set value. The oil pressure in the pressure oil chamber 1601 acts on the control valve 18 at the same time, and will drive the first valve ball 1801 to squeeze the second spring 1802. The second spring 1802 is compressed, and the oil return circuit 1603 is opened. The hydraulic oil in the pressure oil chamber 1601 flows back to the fuel tank 24 through the oil return circuit 1603. During this process, the volume of the pressure oil chamber 1601 decreases. At the same time, under the extrusion of the piston rod 101, the pressure in the oil discharge chamber 1503 will also exceed the opening pressure of the control valve core 8, and the oil discharge port 7 will be opened. The hydraulic oil in the oil discharge chamber 1503 flows through the oil discharge port 7, the groove 1504, the second annular oil groove 1502, and the oil discharge hole 1104 in sequence and discharges to the fuel tank 24, so that the hydraulic oil in the piston chamber 102 can be reduced, the piston rod 101 is pushed to move leftward, and the piston rod 101 will also be pushed leftward. Driven by the linkage rod 10, the first valve stem 12, the second valve stem 13, and the third valve stem 15 move leftward synchronously with the piston rod 101.

[0087] D. When the thrust is extremely large, the piston rod 101 will not be pushed infinitely leftward. The bracket 36 will abut against the limit baffle 33 to limit the left extreme position of the guide wheel 37 to protect the oil cylinder 1.

[0088] This embodiment also provides a crawler vehicle, including the crawler tensioning system in the above solution.

[0089] Crawler vehicles have the characteristics of large traction force, low ground contact pressure, and strong climbing ability, and are widely used in the fields of construction machinery, mining machinery, construction machinery, etc., such as excavators, pile driving machinery, drills, pavers, bulldozers and other machinery. The crawler tensioning system has a great impact on the performance of crawler vehicles. If the pre-tensioning force is too large, the crawler rigidity will be too large, and the crawler tensioning system will not play a buffering role, resulting in an increase in internal friction of the crawler vehicle, causing engine power loss and accelerating crawler wear; if the pre-tensioning force is too small, the crawler will be loose, prone to tooth skipping and vibration, and even derailment will occur.

[0090] The crawler vehicle provided by the present invention adopts the above-mentioned crawler tensioning system, which includes an oil cylinder 1, an oil inlet pipeline 2, an accumulator 3, a first one-way valve 4, a second one-way valve 5, a pressure reducing valve 6, an oil drain pipeline and a control spool 8. The piston rod 101 of the oil cylinder 1 is connected to a bracket 36, and the bracket 36 is used for installing a guide wheel 37. The oil inlet pipeline 2 is connected to the piston chamber 102 of the oil cylinder 1. Along the flow direction of the oil, the first one-way valve 4, the accumulator 3, the second one-way valve 5 and the pressure reducing valve 6 are sequentially arranged on the oil inlet pipeline 2, and both the first one-way valve 4 and the second one-way valve 5 are configured to only allow the oil to flow in the direction of the piston chamber 102. The oil drain pipeline communicates with the piston chamber 102, and the oil drain pipeline has an oil drain port 7 communicating with an oil tank 24. The control spool 8 is used to open or close the oil drain port 7, and only when the oil pressure of the hydraulic oil in the oil drain pipeline is greater than the opening pressure of the control spool 8, the control spool 8 is opened by the hydraulic oil to open the oil drain port 7. When the crawler encounters an obstacle, an uneven road surface or turns, the crawler will push the guide wheel 37 to compress the piston rod 101 to retract. However, since the opening pressure of the control spool 8 is proportional to the retraction stroke of the piston rod 101, initially the retraction stroke of the piston rod 101 is small, and the control spool 8 is easily flushed open by the oil pressure. But as the piston rod 101 is continuously compressed, the retraction stroke of the piston rod 101 becomes larger and larger, and the opening pressure of the control spool 8 is also greater, which can prevent the guide wheel 37 from moving instantly to the leftmost side.

[0091] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A crawler tensioning system, characterized in that, Comprising: An oil cylinder (1), the piston rod (101) of the oil cylinder (1) is connected to a bracket (36), and the bracket (36) is used for installing a guide wheel (37); An oil inlet oil circuit (2), connected to the piston chamber (102) of the oil cylinder (1); An accumulator (3), arranged in the oil inlet oil circuit (2); A first one-way valve (4) and a second one-way valve (5), both arranged in the oil inlet oil circuit (2), the first one-way valve (4) and the second one-way valve (5) are respectively located upstream and downstream of the accumulator (3), and both the first one-way valve (4) and the second one-way valve (5) are configured to only allow the oil to flow in the direction of the piston chamber (102); A pressure reducing valve (6), arranged in the oil inlet oil circuit (2), the pressure reducing valve (6) is located downstream of the accumulator (3) and upstream of the second one-way valve (5); An oil drain oil circuit, communicating with the piston chamber (102), and the oil drain oil circuit has an oil drain port (7) communicating with an oil tank (24); A control spool (8), used to open or close the oil drain port (7), and only when the oil pressure of the hydraulic oil in the oil drain oil circuit is greater than the opening pressure of the control spool (8), the control spool (8) is opened by the hydraulic oil under the action of the hydraulic oil, and the opening pressure of the control spool (8) is proportional to the retraction stroke of the piston rod (101).

2. The crawler tensioning system according to claim 1, characterized in that, The crawler tensioning system further comprises: A boosting assembly, capable of moving relative to the control spool (8); A first spring (9), with both ends respectively abutting against the boosting assembly and the control spool (8), and the first spring (9) is always in a compressed state; A linkage rod (10), connecting the piston rod (101) of the oil cylinder (1) and the boosting assembly, and when the piston rod (101) retracts, the linkage rod (10) drives the boosting assembly to squeeze the first spring (9).

3. The crawler tensioning system according to claim 2, characterized in that, The boosting assembly includes: A valve housing (11), having a first accommodation cavity (1101); A first valve rod (12), slidably arranged in the first accommodation cavity (1101); A second valve rod (13), threadedly connected to the first valve rod (12), and the linkage rod (10) is clamped by the first valve rod (12) and the second valve rod (13); A first plug (14), arranged on the second valve rod (13), and both ends of the first spring (9) respectively abut against the first plug (14) and the control spool (8).

4. The crawler tensioning system according to claim 3, characterized in that, The first plug (14) is threadedly connected to the second valve rod (13).

5. The crawler tensioning system according to claim 3, characterized in that, The valve housing (11) is further provided with a second accommodation cavity (1102) communicating with the first accommodation cavity (1101), and the inner diameter of the second accommodation cavity (1102) is smaller than the inner diameter of the first accommodation cavity (1101); The track tensioning system further includes a third valve stem (15) slidably disposed in the second accommodation cavity (1102) and a valve body (16) disposed on the valve housing (11). The third valve stem (15) is located between the valve body (16) and the control valve core (8). When the control valve core (8) closes the oil drain port (7), the first spring (9) presses the control valve core (8) against the third valve stem (15). The third valve stem (15) is slidably engaged with the first valve stem (12), and the first valve stem (12) can abut against the third valve stem (15) and drive the third valve stem (15) to move synchronously away from the valve body (16). The valve body (16) and the valve housing (11) enclose a pressure oil cavity (1601). The valve body (16) is provided with an oil replenishing oil path (1602) and an oil return oil path (1603) both communicating with the pressure oil cavity (1601). The track tensioning system further includes an oil replenishing check valve (17) disposed in the oil replenishing oil path (1602). The oil replenishing check valve (17) is configured to only allow oil to flow from the fuel tank (24) into the pressure oil cavity (1601). The pressure oil cavity (1601) is configured to unload from the oil return oil path (1603) when the pressure of the hydraulic oil therein exceeds a set value, and the set value is greater than the maximum elastic force given to the control valve core (8) by the first spring (9).

6. The crawler tensioning system according to claim 5, characterized in that, The oil drain oil path includes an oil inlet hole (1103) and an oil drain hole (1104) disposed on the valve housing (11), a first annular oil groove (1501), a second annular oil groove (1502) and an oil drain cavity (1503) all disposed on the third valve stem (15), and a groove (1504) disposed on the third valve stem (15). The oil inlet hole (1103) is respectively communicated with the piston cavity (102) and the first annular oil groove (1501). The first annular oil groove (1501) is always communicated with the oil drain cavity (1503). The oil drain port (7) is respectively communicated with the oil drain cavity (1503) and the groove (1504). The groove (1504) is communicated with the second annular oil groove (1502). The oil drain hole (1104) is respectively communicated with the second annular oil groove (1502) and the fuel tank (24). The control valve core (8) is movably located in the groove (1504).

7. The crawler tensioning system according to any one of claims 1 - 6, characterized in that, The track tensioning system further includes a switching valve and a pressure detecting member (32) disposed in the oil inlet oil path (2). The switching valve is located upstream of the first check valve (4). The pressure detecting member (32) is located between the first check valve (4) and the pressure reducing valve (6) and is used to detect the oil pressure of the oil inlet oil path (2). When the oil pressure detected by the pressure detecting member (32) exceeds a preset pressure, the switching valve closes.

8. The crawler tensioning system according to any one of claims 1 - 6, characterized in that, The crawler tensioning system further includes a limit baffle (33) disposed between the cylinder block of the oil cylinder (1) and the bracket (36), and the limit baffle (33) can abut against the bracket (36) to prevent the bracket (36) from moving towards the cylinder block.

9. The crawler tensioning system according to any one of claims 1 - 6, characterized in that, The crawler tensioning system further includes a throttle valve (35) disposed in the oil inlet pipeline (2), and the throttle valve (35) is located downstream of the second one-way valve (5).

10. A crawler vehicle, characterized in that, It includes the crawler tensioning system according to any one of claims 1-9.

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