External high-horsepower tractor lifter

Abstract

The invention discloses an external high-horsepower tractor lifter, and relates to the technical field of tractor lifters, the external high-horsepower tractor lifter comprises a suspension unit assembled on a tractor, a lifting arm and a driving rod for driving the lifting arm are rotatably arranged on the suspension unit, and the driving rod comprises an extension rod and a shell nested outside the extension rod. According to the external high-horsepower tractor lifter, the area below the end face of the outer sleeve is communicated with the inner sleeve to form a low-driving-force oil duct, at the moment, the oil pumping force of an oil pump is weak, the power of the oil pump is low, and the oil pumping energy consumption of the oil pump in a low-load state is reduced. Under the state of loading a high-weight farm tool, the thrust of a piston formed by the outer sleeve and the sliding sleeve on the piston and the extension rod is increased, the loading capacity on the farm tool is obviously improved, even if overload is generated, the piston is subjected to violent downward pressure and drives the sliding sleeve to move downwards, and at the moment, high-pressure hydraulic oil in the middle oil cavity enters the inner sleeve; the oil pressure is kept in a low-pressure state.

Description

Technical Field

[0001] The invention relates to the technical field of tractor hoists, in particular to an external high-horsepower tractor hoist. Background Art

[0002] Designed specifically for heavy agricultural machinery, the external high-horsepower tractor hoist features a fluid power system at its core. High-displacement cylinders driven by high-pressure hydraulic fluid enable easy lifting of large plows or planters. The system incorporates a fluid pressure brake to ensure smooth lifting and controlled lowering, enabling precise adjustment and reliable parking, significantly improving the operating efficiency and safety of high-horsepower tractors in demanding conditions.

[0003] Patent publication number CN116498608A discloses a tractor and a tractor hoist, relating to a tractor hoist and a tractor equipped with the same. By specifically configuring a distributor in the hoist, especially an automatic actuator of the distributor, the flow and direction of hydraulic oil are changed to control the lifting arm components of the tractor hoist and drive the implement to the required operating position. While ensuring stability and high efficiency, the manufacturing and use costs are reasonably controlled.

[0004] However, in the above patent, since the oil inlet, the elevator descending oil port and the oil return port are connected to the long through hole in sequence, they are connected in pairs through the movement of the distributor valve core, that is, the oil inlet is connected to the ascending oil port, and the oil return port is connected to the descending oil port. Therefore, when the hydraulic rod is overloaded due to the excessive weight of the agricultural implement, the ascending oil port will bear part of the oil overflow caused by the overload. This part of the oil overflow will form resistance at the top of the large cylindrical surface of the cone, causing the oil pressure at this position to rise and blocking the oil inlet from continuing to supply oil. When the oil supply of the oil inlet is restricted, a high oil pressure environment will be formed at the bottom of the large cylindrical surface of the cone, resulting in uneven pressure on the valve core, which will cause stress concentration problems and even cause bulging of the inner cavity in severe cases. Summary of the Invention

[0005] The purpose of the present invention is to provide an external high-horsepower tractor lifter to solve the above problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an external high-horsepower tractor hoist, comprising a suspension unit mounted on the tractor, on which a lifting arm and a drive rod for driving the lifting arm are rotatably mounted, wherein the drive rod comprises an extension rod and a housing nested outside the extension rod, wherein a piston is fixedly mounted on the extension rod, and wherein the housing defines an upper oil chamber and a middle oil chamber at the upper and lower ends of the piston, respectively; It also includes an inner sleeve fixedly arranged in the middle oil chamber, and the piston cooperates with the inner sleeve piston to form a low-drive oil passage; An outer sleeve sliding on the inner sleeve is provided with a sliding sleeve for sealing the inner sleeve, and the sliding sleeve and the inner wall of the middle oil cavity are enclosed to form a high-drive oil channel; The sliding sleeve is subjected to oil pressure changes to switch the hydraulic oil between the low-drive oil channel and the high-drive oil channel; Also included is an oil inlet pipe for supplying hydraulic oil.

[0007] Preferably, it also includes an upper oil outlet pipe and a lower oil outlet pipe respectively opened on the side wall and bottom of the middle oil cavity.

[0008] Preferably, a front movable block and a rear movable block for controlling oil output are slidably provided in the oil inlet pipe.

[0009] Preferably, a side flow channel for connecting the middle oil chamber and the upper oil chamber is further included, and a block for blocking the side flow channel is slidably provided at the port of the side flow channel.

[0010] Preferably, the shell is provided with an extension screw for adjusting the blocking force of the block.

[0011] Preferably, a cover is slidably mounted on the extension screw.

[0012] Preferably, a pressure ring is provided on the outer sleeve and is used to separate the middle oil cavity into different pressure areas.

[0013] Preferably, the outer sleeve is provided with a second elastic member for making the pressure ring tightly adhere to the outer sleeve.

[0014] Preferably, the invention further comprises a locking rocker arm which is arranged in a circumferential array on the piston and is used to lock the piston at a predetermined height.

[0015] Preferably, a wing plate is fixedly provided on the locking rocker arm.

[0016] The present invention has the following beneficial effects: The area below the end surface of the outer sleeve communicates with the inner sleeve, forming a low-drive oil passage. This reduces the pumping force and power of the oil pump, thereby reducing pumping energy consumption under low-load conditions. When loaded with heavy agricultural implements, the "piston" formed by the outer sleeve and sliding sleeve exerts increased thrust on the piston and extension rod, significantly improving the load capacity of the agricultural implement. Even if an overload occurs, the piston is subjected to intense downward pressure, driving the sliding sleeve downward. At this time, the high-pressure hydraulic oil in the middle oil chamber enters the inner sleeve, maintaining low oil pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0018] Figure 1 An overall three-dimensional schematic diagram provided for an embodiment of the present invention; Figure 2 A schematic diagram of the driving rod structure provided by an embodiment of the present invention; Figure 3 A schematic diagram of the internal structure of a driving rod provided in an embodiment of the present invention; Figure 4 Provides a schematic diagram of the extension rod and housing structure for an embodiment of the present invention; Figure 5 A schematic diagram of the internal structure of an extension rod provided in an embodiment of the present invention; Figure 6 A schematic diagram of the flow direction of a low-drive oil channel provided by an embodiment of the present invention; Figure 7 The embodiment of the present invention provides Figure 6 A magnified schematic diagram of the structure B in the middle; Figure 8 A schematic diagram of the upward movement structure under low load conditions provided by an embodiment of the present invention; Figure 9 The embodiment of the present invention provides Figure 8 A magnified schematic diagram of the C structure in the middle; Figure 10 A schematic diagram of the flow direction of a high-drive oil channel provided by an embodiment of the present invention; Figure 11 The embodiment of the present invention provides Figure 10 A magnified schematic diagram of the D structure in the middle; Figure 12 A schematic diagram of the flow direction of a high-drive oil channel under an overload state provided by an embodiment of the present invention; Figure 13 The embodiment of the present invention provides Figure 12 Middle E is an enlarged schematic diagram of the structure; Figure 14 A schematic diagram of the locking rocker structure provided by an embodiment of the present invention; Figure 15 A schematic diagram of the oil inlet pipe structure provided by an embodiment of the present invention; Figure 16 The embodiment of the present invention provides Figure 3 A magnified schematic diagram of the structure in the middle.

[0019] Description of reference numerals: 1. Housing; 11. Upper oil chamber; 12. Inner sleeve; 121. Raised portion; 13. First outer sleeve chamber; 14. Lower oil chamber; 15. Second outer sleeve chamber; 16. Middle oil chamber; 2. Lifting arm; 3. Extension rod; 31. Piston; 32. Sliding sleeve; 321. First elastic member; 33. Outer sleeve; 331. Second elastic member; 34. Pressing ring; 35. Through pipe; 36. First spring; 37. Fixing rod; 4. Oil inlet pipe; 41. Telescopic rod; 42. Upper oil outlet pipe; 43. Lower oil outlet pipe; 44. Front movable block; 45. Rear movable block; 5. Oil return pipe; 6. Extension screw; 61. Block; 62. Second spring; 63. Sliding block; 64. Side flow channel; 65. Sealing cover; 66. Pressure relief chamber; 7. Locking rocker; 71. Trigger member; 72. Pressure member; 73. Rotating rod; 74. Movable groove; 75. Wing plate. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] like Figure 1-16 As shown, an external high-horsepower tractor hoist includes a suspension unit mounted on the tractor, on which a lifting arm 2 and a driving rod for driving the lifting arm 2 are rotatably arranged, and the driving rod includes an extension rod 3 and a housing 1 (such as a housing 1) nested outside the extension rod 3. Figure 1 and Figure 2 As shown), a piston 31 is fixedly provided on the extension rod 3, and the housing 1 is provided with an upper oil chamber 11 and a middle oil chamber 16 at the upper and lower ends of the piston 31 (as shown). Figure 3 shown); It also includes an inner sleeve 12 (such as Figure 3 As shown), the piston 31 cooperates with the inner sleeve 12 piston to form a low-drive oil passage; An outer sleeve 33 slides on the inner sleeve 12, on which a sliding sleeve 32 is provided for sealing the inner sleeve 12, and the outer sleeve 33 and the inner wall of the middle oil cavity 16 are enclosed to form a high-drive oil passage; The sliding sleeve 32 is subjected to oil pressure changes to switch the hydraulic oil between the low-drive oil channel and the high-drive oil channel; It also includes an oil inlet pipe 4 for supplying hydraulic oil.

[0022] Specifically, it also includes a fixed rod 37 fixedly arranged in the shell 1, the lower end of the extension rod 3 is slidably arranged on the fixed rod 37, and a return oil pipe 5 is arranged on the suspension unit and connected to the upper oil chamber 11, wherein the return oil pipe 5 and the oil inlet pipe 4 are both controlled by a distributor (the setting of the distributor can adopt a conventional tractor hoist distributor, which is a conventional technical means well known to those skilled in the art and will not be described in detail here). When the drive rod is extended (that is, the extension rod 3 moves upward, at this time the total length of the drive rod increases, and accordingly, the extension rod 3 moves downward, which means that the drive rod is contracted), the oil inlet pipe 4 transports hydraulic oil to the middle oil chamber 16, and at the same time, the hydraulic oil in the upper oil chamber 11 is drawn into the return oil pipe 5, and the extension rod 3 moves upward; and when the drive rod is contracted (that is, the extension rod 3 moves downward), the return oil pipe 5 transports hydraulic oil to the upper oil chamber 11, and the hydraulic oil in the middle oil chamber 16 is drawn back to the oil inlet pipe 4 (the above technology is a conventional setting of the hydraulic rod, which is technical common sense well known to those skilled in the art and will not be described in detail here).

[0023] The sliding sleeve 32 slides on the fixed rod 37, and the outer sleeve 33 is located between the inner sleeve 12 and the inner wall of the middle oil chamber 16 (as shown in FIG. Figure 3 As shown), the outer sleeve 33 and the sliding sleeve 32 are connected by a first elastic member 321 and a gap is maintained.

[0024] Furthermore, when the driving rod is equipped with a low-weight agricultural implement, the driving rod is in a low-load state, and the pumping force of the oil pump is weak. At this time, the hydraulic oil pressure in the middle oil chamber 16 is low, and the first elastic member 321 maintains its original shape. At this time, the hydraulic oil enters the inner sleeve 12 along the gap between the outer sleeve 33 and the sliding sleeve 32 (as shown in FIG. Figure 6 In the direction indicated by the middle arrow), at this time, the area below the end surface of the outer sleeve 33 is connected to the inner sleeve 12, forming a low-drive oil channel, and then the hydraulic oil pushes the piston 31 to slide upward along the fixed rod 37. The effective area of ​​the hydraulic action is only the end surface area of ​​the piston 31. Then, the low-pressure hydraulic oil pushes the extension rod 3 to move upward. Because the oil pumping force of the oil pump is weak at this time, the oil pump power is low, which reduces the oil pumping energy consumption under low-load conditions.

[0025] When the driving rod is loaded with a heavy agricultural implement, the driving rod is in a high-load state, and the pumping force of the oil pump is increased. At this time, the hydraulic oil pressure in the middle oil chamber 16 is high, and the high hydraulic oil will push the sliding sleeve 32 to slide upward along the fixed rod 37. The first elastic member 321 is folded, and the outer sleeve 33 and the sliding sleeve 32 are tightly attached. At this time, the sliding sleeve 32 forms a chamber (such as the chamber enclosed by the outer sleeve 33 and the inner sleeve 12) enclosed by the outer sleeve 33 and the inner sleeve 12. Figure 10 The middle dotted line box area) is blocked and the chamber is sealed, and the hydraulic oil pushes the outer sleeve 33 and the sliding sleeve 32 (such as Figure 10The piston 31 then moves upwards through the contact between the upper end of the sliding sleeve 32 and the lower end of the piston 31. The lower end surfaces of the sliding sleeve 32 and piston 31 abut and nest against each other, increasing the contact area and frictional resistance between the sliding sleeve 32 and piston 31. This is known as a high-drive oil passage. The effective area of ​​the hydraulic oil is the combined end surface area of ​​the outer sleeve 33 and sliding sleeve 32, effectively forming a larger "piston" with the outer sleeve 33 and sliding sleeve 32. At this point, the sliding sleeve 32 and piston 31 maintain synchronized movement (detailed connection details are provided below). Furthermore, due to the pressure exerted by the hydraulic oil in the upper oil chamber 11 on the upper end of the piston 31, the piston 31 maintains a downward bias, preventing it from easily separating from the sliding sleeve 32. This "piston" formed by the outer sleeve 33 and sliding sleeve 32 exerts a greater thrust on the piston 31 and the extension rod 3, significantly improving the load capacity of the agricultural implement.

[0026] Furthermore, when the implement needs to be lowered, oil enters the upper oil chamber 11 and oil exits the middle oil chamber 16. At this time, the piston 31 drives the sliding sleeve 32 downward (the specific transmission method is described below). The gap between the sliding sleeve 32 and the outer sleeve 33 increases, and part of the hydraulic oil in the middle oil chamber 16 enters the inner sleeve 12, thereby reducing the actual amount of oil discharged from the middle oil chamber 16, shortening the time required to lower the implement, and achieving rapid resetting.

[0027] When an overload occurs under high load conditions, the piston 31 experiences intense downward pressure, driving the sliding sleeve 32 downward. This increases the gap between the sliding sleeve 32 and the outer sleeve 33, allowing the high-pressure hydraulic oil in the middle oil chamber 16 to enter the inner sleeve 12 to relieve pressure. (Previously, the sliding sleeve 32 sealed the chamber formed by the outer sleeve 33 and inner sleeve 12; the hydraulic oil pressure in the inner sleeve 12 corresponds to the pressure at low load on the drive rod.) Consequently, the hydraulic oil pressure in the middle oil chamber 16 remains low, preventing bulging and deformation caused by excessive pressure in the middle oil chamber 16 when the piston 31 is overloaded. Furthermore, as the hydraulic oil in the middle oil chamber 16 enters the inner sleeve 12, the lower end surface of the piston 31 is supported by the hydraulic oil in the inner sleeve 12, providing a damping effect and preventing the piston 31 from rapidly falling.

[0028] In the above-described technology, the area below the end surface of the outer sleeve 33 communicates with the inner sleeve 12, forming a low-drive oil passage. This reduces the pumping force and power of the oil pump, thereby reducing pumping energy consumption under low-load conditions. However, when loaded with a heavy implement, the "piston" formed by the outer sleeve 33 and sliding sleeve 32 exerts increased thrust on the piston 31 and extension rod 3, significantly improving the implement's load capacity. Even in the event of an overload, the piston 31 experiences intense downward pressure, driving the sliding sleeve 32 downward. At this point, the high-pressure hydraulic oil in the middle oil chamber 16 enters the inner sleeve 12, maintaining low oil pressure.

[0029] As an embodiment provided by the present invention, an upper oil outlet pipe 42 and a lower oil outlet pipe 43 (such as Figure 3 shown).

[0030] Specifically, the housing 1 defines a lower oil chamber 14 directly below the middle oil chamber 16. A lower oil outlet pipe 43 connects the lower oil chamber 14 to the oil inlet pipe 4. A through-tube 35 is fixedly mounted on the fixed rod 37. The through-tube 35 is located at the upper end of the lower oil chamber 14 and faces the sliding sleeve 32. When the oil pump's output pressure is low, hydraulic oil enters the middle oil chamber 16 through the upper oil outlet pipe 42 on the sidewall of the middle oil chamber 16. The hydraulic oil then pushes against the piston 31 through the low-drive oil passage. When the oil pump's output pressure is high, the hydraulic oil flows upward through the lower oil chamber 14. As it passes through the through-tube 35, it is provided with multiple through-holes that converge the hydraulic oil, causing it to surge into the middle oil chamber 16 with a greater impact force. The hydraulic oil then pushes the sliding sleeve 32 upward along the fixed rod 37.

[0031] As another embodiment provided by the present invention, a front movable block 44 and a rear movable block 45 (such as Figure 15 shown).

[0032] Specifically, the oil inlet pipe 4 is provided with a telescopic rod 41 (which can be driven by conventional means such as an electric telescopic rod or a hydraulic rod), and a front movable block 44 and a rear movable block 45 are assembled into one body. A hollow tube is fixedly provided at the center of the front movable block 44 and the rear movable block 45. Under low load conditions, the oil pressure is relatively low. At this time, the rear movable block 45 blocks the port of the lower oil outlet pipe 43. The front end face of the front movable block 44 is offset from the port of the upper oil outlet pipe 42. The hydraulic oil reaches the front end face of the front movable block 44 through the hollow tube and enters the upper oil outlet pipe 42. Under high load conditions, the oil pressure increases, driving the telescopic rod 41 forward, causing the front movable block 44 to block the port of the upper oil outlet pipe 42. After the front movable block 44 moves a certain distance, it abuts against the inner wall of the oil inlet pipe 4, thereby blocking the hollow tube. At the same time, the rear movable block 45 no longer blocks the port of the lower oil outlet pipe 43, allowing the hydraulic oil to enter the lower oil outlet pipe 43.

[0033] As another embodiment provided by the present invention, it also includes a side channel 64 for connecting the middle oil chamber 16 and the upper oil chamber 11, and a blocking block 61 for blocking the side channel 64 is slidably provided at the end of the side channel 64.

[0034] Specifically, a pressure relief chamber 66 is provided on the housing 1, and a block 61 is slidably provided in the pressure relief chamber 66, a sliding block 63 is also slidably provided in the pressure relief chamber 66, the block 61 is passed through the sliding block 63, and a second spring 62 is provided between the block 61 and the sliding block 63. The housing 1 is also equipped with an extension screw 6, the upper end of the extension screw 6 extends out of the housing 1, and the lower end is threadedly engaged with the sliding block 63 (such as Figure 16 shown).

[0035] Furthermore, when the oil pressure in the middle oil chamber 16 is normal, the second spring 62 presses against the block 61, so that the block 61 blocks the side flow channel 64. At this time, the middle oil chamber 16 and the upper oil chamber 11 are not connected to each other. When the oil pressure in the middle oil chamber 16 is too high, the oil will overcome the elastic force of the second spring 62 and push the block 61, so that the side flow channel 64 is opened, and the oil will enter the upper oil chamber 11 from the middle oil chamber 16, thereby balancing the oil pressure.

[0036] Furthermore, the sliding block 63 can be driven to move vertically up and down by rotating the upper end of the extension screw 6, thereby changing the distance between the sliding block 63 and the blocking block 61, thereby tightening or loosening the second spring 62, thereby adjusting the blocking force of the blocking block 61. A through flow channel is provided in the extension screw 6, and a cover 65 for sealing the flow channel is provided at the upper end of the extension screw 6. When the oil pressure is too high, the hydraulic oil will enter the pressure relief chamber 66 and enter the flow channel. The cover 65 will be pushed up by the hydraulic oil, which can alert the user and the cover 65 can be directly removed to relieve the pressure.

[0037] As another embodiment provided by the present invention, it also includes a pressure ring 34 provided on the outer sleeve 33 and used to separate the middle oil cavity 16 into different pressure areas.

[0038] Specifically, the pressure ring 34 is provided with a first spring 36 (such as Figure 3 As shown in FIG, the upper end of the first spring 36 is arranged at the connection between the outer wall of the inner sleeve 12 and the upper end of the inner wall of the middle oil chamber 16, and the lower end of the first spring 36 is arranged at the upper end surface of the pressure ring 34 to keep the pressure ring 34 at a predetermined height. The pressure ring 34 divides the area enclosed by the inner sleeve 12 and the inner wall of the middle oil chamber 16 into two parts, namely the first outer sleeve cavity 13 and the second outer sleeve cavity 15 (as shown in FIG. Figure 3 When the drive rod is under low load, the hydraulic oil flows along the second outer sleeve cavity 15 into the inner sleeve 12, eventually pushing the piston 31 upward. This is the low-drive oil passage.

[0039] When the driving rod is under high load, the extension rod 3 drives the agricultural implement upward, and the hydraulic oil pushes the outer sleeve 33 and the sliding sleeve 32 (such as Figure 10In the direction indicated by the arrow in the middle), the hydraulic oil pushes the "piston" formed by the outer sleeve 33 and the sliding sleeve 32 upward along the second outer sleeve cavity 15. At this time, the hydraulic oil overcomes the elastic force of the first spring 36. During the pushing process, the outer sleeve 33 drives the pressure ring 34 to move upward. At this time, the hydraulic oil in the first outer sleeve cavity 13 generates a large pressure and squeezes the block 61. The hydraulic oil in the first outer sleeve cavity 13 flows to the upper oil chamber 11 (as shown in the arrow direction). Figure 10 As shown by the arrow, the oil flow in the upper oil chamber 11 is drawn into the oil return pipe 5, which can take over this part of the oil flow. The pressure of the hydraulic oil in the first outer shell chamber 13 after pressure relief is lower than that in the second outer shell chamber 15.

[0040] As another embodiment provided by the present invention, a second elastic member 331 is provided on the outer sleeve 33 to enable the pressure ring 34 to be tightly attached to the outer sleeve 33 .

[0041] Specifically, when the driving rod is under high load, the hydraulic oil in the middle oil chamber 16 is drawn back into the oil inlet pipe 4 during the process of the extension rod 3 descending. At this time, the outer sleeve 33 moves downward along the fixed rod 37, and the distance between the outer sleeve 33 and the pressure ring 34 increases, forming a channel between the adjacent end surfaces of the two, so that the hydraulic oil in the second outer sleeve cavity 15 enters the first outer sleeve cavity 13 through the channel (as shown in FIG. Figure 12 As shown in FIG. 1 ), at this time, part of the hydraulic oil in the second outer sleeve cavity 15 enters the inner sleeve 12, and part enters the first outer sleeve cavity 13. The remaining part is the displacement actually drawn back into the oil inlet pipe 4, so that the displacement generated during the descent process is relatively small. Combined with the pressure exerted by the weight of the agricultural implement on the extension rod 3, the speed of the agricultural implement descent is accelerated. During the descent process, hydraulic oil is always present as a buffer, and the problem of oil pressure surge caused by the pressure generated by the descent of the agricultural implement is avoided.

[0042] As another embodiment provided by the present invention, it also includes a locking rocker 7 which is arranged in a circumferential array on the piston 31 and is used to lock the piston 31 at a predetermined height.

[0043] Specifically, the upper end of the locking rocker 7 is fixedly provided with a trigger member 71, and the lower end is rotatably provided with a pressing member 72, and the inner wall of the inner sleeve 12 is provided with a plurality of protrusions 121 (such as Figure 5 As shown), a movable groove 74 is further provided in the locking rocker arm 7, and a rotating rod 73 is rotatably provided on the upper end of the sliding sleeve 32, and the end of the rotating rod 73 is movably provided in the movable groove 74.

[0044] When the extension rod 3 moves upward normally under low load, the hydraulic oil flows along the low driving force channel (i.e., enters the inner sleeve 12 along the second outer sleeve cavity 15), and the piston 31 moves upward under the pressure of the oil, while the position of the sliding sleeve 32 remains unchanged. At this time, the rotating rod 73 on the sliding sleeve 32 pulls the movable groove 74, so that the end of the rotating rod 73 slides along the upper end of the movable groove 74 to the lower end (as shown in FIG. Figure 7 Event to Figure 9 State), the locking rocker arm 7 is deflected as a whole toward the axis center of the middle oil chamber 16. At this time, the pressing member 72 is not in contact with the protrusion 121, and does not affect the normal upward movement of the piston 31.

[0045] When the extension rod 3 moves upward normally under high load, the sliding sleeve 32 first moves upward and contacts the lower end of the piston 31, and then the sliding sleeve 32 drives the piston 31 to move upward. At this time, the rotating rod 73 and the locking rocker 7 are relatively stationary and both are in a free state. Subsequently, when the extension rod 3 moves downward, the hydraulic oil in the second outer sleeve cavity 15 is pumped back into the oil inlet pipe 4. Due to the reduction in oil pressure in the second outer sleeve cavity 15, the elasticity of the first spring 36 is released and pushes the sliding sleeve 32 downward. The sliding sleeve 32 moves downward relative to the piston 31 and is released by the first elastic The part 321 drives the outer sleeve 33 to move, and the rotating rod 73 on the sliding sleeve 32 pulls the movable groove 74, so that the end of the rotating rod 73 slides along the upper end of the movable groove 74 to the lower end, so that the multiple locking rocker bars 7 deflect toward the center of the middle oil chamber 16 axis, and the pressing part 72 is staggered from the protrusion 121. Then the piston 31 and the sliding sleeve 32 both move downward until the hydraulic oil pressure in the second outer sleeve cavity 15 drops to the minimum, the deformation of the first elastic part 321 is restored, and the distance between the sliding sleeve 32 and the outer sleeve 33 is maintained at the initial position, completing the reset.

[0046] As another embodiment provided by the present invention, a wing plate 75 is fixedly provided on the locking rocker 7 .

[0047] Specifically, when the extension rod 3 is overloaded, the piston 31 moves downward relative to the sliding sleeve 32. At this time, due to the arrangement of the wing plate 75, the wing plate 75 is pushed by the hydraulic oil from below during the downward movement of the locking rocker 7, causing the locking rocker 7 to deflect away from the axis and open. At this time, the pressing piece 72 on the locking rocker 7 abuts against the inner sleeve 12, and the protrusion 121 is engaged with the pressing piece 72 to lock, achieving the effect of self-locking when falling (such as Figure 11 At the same time, the deflection of the locking rocker 7 drives the trigger member 71 to deflect, and the trigger member 71 presses the upper end of the sliding sleeve 32 downward when it deflects, causing the sliding sleeve 32 to move downward (as shown). Figure 11 As shown), the distance between the sliding sleeve 32 and the outer sleeve 33 is increased, and part of the hydraulic oil in the second outer sleeve cavity 15 enters the inner sleeve 12, and part enters the first outer sleeve cavity 13, which plays a role in pressure relief (as shown in FIG. Figure 12 shown).

[0048] Working principle: When the output oil pressure of the oil pump is low, the hydraulic oil enters the middle oil chamber 16 through the upper oil outlet pipe 42 on the side wall of the middle oil chamber 16, and then the hydraulic oil pushes the piston 31 through the low-drive oil channel; when the output oil pressure of the oil pump is high, the hydraulic oil goes upward through the lower oil chamber 14, and when passing through the through pipe 35, a plurality of through holes are opened on the through pipe 35, which bundles the hydraulic oil, so that the hydraulic oil rushes into the middle oil chamber 16 with a greater impact force, and then the hydraulic oil pushes the sliding sleeve 32 to move upward along the fixed rod 37.

[0049] When the driving rod is in a low-load state, the pumping force of the oil pump is weak. At this time, the hydraulic oil pressure in the middle oil chamber 16 is low, and the first elastic member 321 maintains its original shape. At this time, the hydraulic oil enters the inner sleeve 12 along the gap between the outer sleeve 33 and the sliding sleeve 32 (as shown in FIG. Figure 6 In the direction indicated by the middle arrow), the area below the end surface of the outer sleeve 33 is connected to the inner sleeve 12 to form a low-drive oil channel, and then the hydraulic oil pushes the piston 31 to slide upward along the fixed rod 37.

[0050] When the driving rod is under high load, the extension rod 3 drives the agricultural implement upward, and the pumping force of the oil pump increases. At this time, the hydraulic oil pressure in the middle oil chamber 16 is high, and the high hydraulic oil will push the sliding sleeve 32 to slide upward along the fixed rod 37. The first elastic member 321 is folded, and the outer sleeve 33 and the sliding sleeve 32 are tightly attached. At this time, the sliding sleeve 32 forms a cavity (such as the cavity) enclosed by the outer sleeve 33 and the inner sleeve 12. Figure 10 The middle dotted line box area) is blocked and the chamber is sealed, and the hydraulic oil pushes the outer sleeve 33 and the sliding sleeve 32 (such as Figure 10 The upper end of the sliding sleeve 32 abuts against the lower end surface of the piston 31, driving the piston 31 upward. The sliding sleeve 32 and the lower end surface of the piston 31 abut against each other and then nest with each other, thereby increasing the contact area and improving the friction resistance between the sliding sleeve 32 and the piston 31. This is the high-drive oil channel.

[0051] During the pushing process, the outer sleeve 33 drives the pressure ring 34 to move upward. At this time, the hydraulic oil in the first outer sleeve cavity 13 generates a large pressure and pushes the block 61. The hydraulic oil in the first outer sleeve cavity 13 flows to the upper oil chamber 11 (as shown in FIG. Figure 10 As shown by the arrow, the oil flow in the upper oil chamber 11 is drawn into the oil return pipe 5, which can take over this part of the oil flow. The pressure of the hydraulic oil in the first outer shell chamber 13 after pressure relief is lower than that in the second outer shell chamber 15.

[0052] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. An external high-horsepower tractor hoist, comprising a suspension unit mounted on the tractor, on which a lifting arm (2) and a driving rod for driving the lifting arm (2) are rotatably arranged, and the driving rod comprises an extension rod (3) and a housing (1) nested outside the extension rod (3), characterized in that: A piston (31) is fixedly provided on the extension rod (3), and the housing (1) is provided with an upper oil chamber (11) and a middle oil chamber (16) at the upper and lower ends of the piston (31). It also includes an inner sleeve (12) fixedly arranged in the middle oil cavity (16), and the piston (31) cooperates with the piston of the inner sleeve (12) to form a low-drive oil passage; An outer sleeve (33) sliding on the inner sleeve (12) is provided with a sliding sleeve (32) for sealing the inner sleeve (12), and is enclosed with the inner wall of the middle oil cavity (16) to form a high-drive oil passage; The sliding sleeve (32) is subjected to oil pressure activity changes to switch the hydraulic oil between the low-drive oil channel and the high-drive oil channel; It also includes an oil inlet pipe (4) for supplying hydraulic oil.

2. The external high-horsepower tractor lifter according to claim 1, characterized in that: It also includes an upper oil outlet pipe (42) and a lower oil outlet pipe (43) respectively opened on the side wall and bottom of the middle oil cavity (16).

3. The external high-horsepower tractor lifter according to claim 1, characterized in that: A front movable block (44) and a rear movable block (45) for controlling oil discharge are slidably provided in the oil inlet pipe (4).

4. The external high-horsepower tractor lifter according to claim 1, characterized in that: It also includes a side flow channel (64) for connecting the middle oil chamber (16) and the upper oil chamber (11), and a blocking block (61) for blocking the side flow channel (64) is slidably provided at a port of the side flow channel (64).

5. The external high-horsepower tractor lifter according to claim 4, characterized in that: The housing (1) is provided with an extension screw (6) for adjusting the blocking force of the blocking block (61).

6. The external high-horsepower tractor lifter according to claim 5, characterized in that: A cover (65) is slidably mounted on the extension screw (6).

7. The external high-horsepower tractor lifter according to claim 1, characterized in that: It also includes a pressure ring (34) disposed on the outer sleeve (33) and used to separate the middle oil cavity (16) into different pressure areas.

8. The external high-horsepower tractor lifter according to claim 7, characterized in that: The outer sleeve (33) is provided with a second elastic member (331) for making the pressure ring (34) tightly adhere to the outer sleeve (33).

9. The external high-horsepower tractor hoist according to claim 1, characterized in that: It also includes a locking rocker (7) which is arranged in a circumferential array on the piston (31) and is used to lock the piston (31) at a predetermined height.

10. The external high-horsepower tractor lifter according to claim 9, characterized in that: A wing plate (75) is fixedly provided on the locking rocker arm (7).

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