A safety hydraulic cylinder for outdoor use and a hydraulic lifting roll-on / roll-off connection bridge

Abstract

The present invention relates to the technical field of hydraulic cylinders, and discloses a safe hydraulic cylinder for outdoor use and a hydraulic lifting and ro-ro connection bridge. Among them, a safe hydraulic cylinder for outdoor use includes a cylinder body, a piston rod disposed in the cylinder body, a cylinder head disposed at the top of the cylinder body, an oil inlet passage and an oil outlet passage disposed on both sides of the cylinder body, and further includes oil seal components respectively disposed inside the oil inlet passage and the oil outlet passage; the oil seal component includes a sealing assembly disposed at the bottom of the oil inlet passage, an unlocking assembly disposed on top of the sealing assembly, and a communication assembly disposed in the oil inlet passage and around the unlocking assembly. Through the linkage design of the sealing assembly and the unlocking assembly, a fully automatic pressure control of "connecting during telescoping and closing during stopping" is achieved, effectively isolating the pressure decay caused by factors such as valve internal leakage and pipeline penetration, enabling the hydraulic cylinder to maintain a precise position for a long time under complex outdoor loads and eliminating the hidden danger of "position drift".

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic cylinders, and in particular to a safe hydraulic cylinder for outdoor use and a hydraulic lifting type roll-on / roll-off connecting bridge. Background Art

[0002] The hydraulic lifting type roll-on / roll-off bridge is the core equipment for ports and docks to achieve efficient connection between ships and land. Its reliability directly affects the traffic safety and loading and unloading efficiency of vehicles and personnel. This equipment relies on hydraulic cylinders as the core lifting drive components. It needs to operate for a long time in harsh outdoor environments with high salt fog, humidity and dust, and frequent heavy loads. It places extremely high demands on the sealing, motion stability and environmental adaptability of the hydraulic cylinders.

[0003] Existing hydraulic cylinders rely on the middle position function of the reversing valve or single-stage seals to achieve oil circuit closure in terms of sealing and pressure maintenance. Factors such as leakage in the valve gap, aging of the seals, and compressibility of the hydraulic oil make it difficult to eliminate the problem of pressure decay. The piston rod is prone to slow drift, especially in scenarios where the position needs to be accurately maintained for a long time, such as docking of ship gangplanks and positioning of container slings. The position may be out of control and cause collision risks or loading and unloading deviations, seriously affecting the safety and accuracy of the operation. In addition, existing hydraulic cylinders generally lack an active chip removal mechanism, and the cylinder head sealing area is easily invaded by impurities such as sea salt particles and sand, and there is no directional guide discharge structure. After the particles are retained or enter the hydraulic oil, they will scratch the seals and block the oil circuit, causing seal failure and component wear; in addition, traditional one-way valves or lip seals are prone to reverse leakage under the action of external pressure (such as seawater moisture), and cannot effectively prevent the invasion of corrosive media, resulting in hydraulic oil emulsification and metal parts rust. In the highly corrosive environment of the port, the problems of short equipment maintenance cycle and high cost are particularly prominent. Summary of the invention

[0004] In view of the problems in the prior art such as leakage in the valve gap, aging of the seals and compressibility of the hydraulic oil, which make it difficult to eliminate the problem of pressure decay and the piston rod prone to slow drift, a safe hydraulic cylinder for outdoor use is proposed.

[0005] Its purpose is to effectively isolate the pressure attenuation caused by factors such as valve leakage and pipeline penetration, so that the hydraulic cylinder can maintain a precise position for a long time under complex outdoor loads and eliminate the hidden danger of "position drift".

[0006] The technical solution of the present invention is a safety hydraulic cylinder for outdoor use, comprising a cylinder body, a piston rod arranged in the cylinder body, a cylinder cover arranged on the top of the cylinder body, an oil inlet channel and an oil outlet channel arranged on both sides of the cylinder body, and also comprising oil seal components respectively arranged inside the oil inlet channel and the oil outlet channel;

[0007] The oil seal component includes a sealing assembly disposed at the bottom of the oil inlet passage, an unlocking assembly disposed on top of the sealing assembly, and a communication assembly disposed in the oil inlet passage and around the unlocking assembly;

[0008] The sealing assembly is used to seal the hydraulic oil in the hydraulic cylinder when the hydraulic cylinder stops telescoping. The communication assembly is used to actively unlock the sealing assembly through the unlocking assembly when the hydraulic oil enters and exits the oil inlet passage, so that the hydraulic oil communicates with the inside of the cylinder body to realize the telescoping of the hydraulic cylinder;

[0009] The sealing assembly includes a telescopic groove opened in the cylinder block base, a spring disposed in the telescopic groove, a sealing column disposed on one side of the spring, and a communication hole opened on the side of the telescopic groove away from the spring.

[0010] Further, one side of the sealing column is frustum-shaped.

[0011] Further, the unlocking assembly includes a moving disk disposed in the oil inlet passage, a communication rod disposed at the bottom of the moving disk, a groove opened at the top of one side of the sealing column, two triangular blocks disposed in the groove, and two lower pressing rods and two upper pulling rods symmetrically disposed at the bottom of the communication rod in sequence.

[0012] Further, in the initial state, the lower pressing rod and the upper pulling rod are respectively in contact with both sides of the triangular block.

[0013] Further, the communication rod is located on one side of the center position of the moving disk.

[0014] Further, the communication assembly includes a plurality of upper communication grooves uniformly opened on one side of the oil inlet passage, and a plurality of lower communication grooves uniformly opened on the other side of the oil inlet passage and obliquely below the upper communication grooves.

[0015] Further, in the initial state, the moving disk is located at the position between the upper communication groove and the lower communication groove and closes both the upper communication groove and the lower communication groove at the same time.

[0016] Further, both the upper communication groove and the lower communication groove are arc-shaped.

[0017] Further, symmetrically arranged double-direction spiral grooves are opened on the inner side of the cylinder head, and inclined chip removal holes are respectively opened at the intersection of the two spiral grooves.

[0018] Another object of the present invention is to provide a hydraulic lifting roll-on / roll-off connection bridge, and its purpose is to: accurately control the hydraulic cylinder to adjust the bridge deck height and slope in real time, ensure that the vehicle always maintains smooth passage during the roll-on / roll-off process, and avoid driving jams and collision risks caused by height misalignment or sudden slope changes.

[0019] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a hydraulic lifting roll-on / roll-off connecting bridge, comprising a carrier plate, and a cylinder body arranged on the carrier plate for lifting the carrier plate.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Through the linkage design of the sealing component and the unlocking component, the fully automatic pressure control of "connected when retracted and closed when stopped" is realized. When the hydraulic oil drives the piston rod to move, the unlocking component squeezes the sealing column to open the oil circuit to ensure smooth flow of hydraulic oil; after the pressure supply is stopped, the spring reset drives the sealing column to seal the connecting hole, forming a rigid locked state, effectively isolating the pressure attenuation caused by factors such as leakage in the valve and pipeline penetration, so that the hydraulic cylinder can still maintain a precise position for a long time under complex outdoor loads, eliminating the hidden danger of "position drift".

[0022] 2. When lifting, the lower pressure rod squeezes the top of the triangular block to quickly open the oil circuit, ensuring that the hydraulic oil quickly pushes the piston rod; when descending, the upper pull rod reversely squeezes the bottom of the triangular block, synchronously unlocks the sealing component, and allows the hydraulic oil in the cylinder to be discharged smoothly. This symmetrical design not only achieves balanced force in two-way movement, but also optimizes the oil flow path through the arc-shaped connecting groove, reduces flow resistance, and reduces the energy consumption of the hydraulic system. At the same time, the pre-contact design of the components in the initial state ensures that the unlocking action responds quickly, significantly reduces movement jams and impacts, and allows the piston rod to maintain stable operation under frequent start-stop or heavy load conditions, thereby improving the safety and comfort of equipment operation.

[0023] 3. When the piston rod moves, the laminar shear and centrifugal force in the spiral groove drive the external invading impurities (such as seawater, mud, and metal debris) to migrate along the spiral trajectory to the chip removal hole, and are discharged in a direction through the one-way valve opened at a low pressure of 0.05MPa, preventing particles from entering the hydraulic system and causing seal wear or oil circuit blockage; at the same time, the one-way valve automatically closes when the external pressure is higher than the internal pressure, effectively preventing the backflow of seawater moisture, preventing the emulsification of hydraulic oil and corrosion of metal parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the hydraulic cylinder of the present invention;

[0025] Figure 2 It is a schematic diagram of the half-section structure inside the hydraulic cylinder base of the present invention;

[0026] Figure 3 It is a schematic diagram of a partially enlarged structure of the oil seal component of the present invention after an overall front section view;

[0027] Figure 4 It is a partial structural schematic diagram of the connection component of the present invention;

[0028] Figure 5Schematic diagram of the overall exploded structure of the sealing component and unlocking component of the present invention;

[0029] Figure 6 Schematic diagram of the mating structure of the sealing component and unlocking component of the present invention;

[0030] Figure 7 Schematic diagram of the overall sectional structure of the cylinder head and piston rod of the present invention;

[0031] Figure 8 Schematic diagram of the structure of the spiral groove of the present invention;

[0032] Figure 9 Schematic diagram of the overall three-dimensional structure of the connection bridge body of the present invention.

[0033] In the figure:

[0034] 1. Cylinder block; 11. Piston rod; 12. Cylinder head; 13. Oil inlet channel; 14. Oil outlet channel; 2. Sealing component; 21. Telescopic groove; 22. Spring; 23. Sealing column; 24. Communication hole; 3. Unlocking component; 31. Moving disk; 32. Communication rod; 33. Groove; 34. Triangular block; 35. Lower pressing rod; 36. Upper pulling rod; 4. Communication component; 41. Upper communication groove; 42. Lower communication groove; 5. Spiral groove; 6. Chip removal hole; 7. Carrier plate. Specific embodiments

[0035] In order to make the above-mentioned objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0036] Example 1, referring to Figures 1-6 , which is the first embodiment of the present invention, provides a safety hydraulic cylinder for outdoor use, including a cylinder block 1, a piston rod 11 installed inside the cylinder block 1, a cylinder head 12 installed on the top of the cylinder block 1, an oil inlet channel 13 and an oil outlet channel 14 installed on both sides of the cylinder block 1, the oil inlet channel 13 and the oil outlet channel 14 are externally connected to a hydraulic pump, and also includes oil seal components respectively installed inside the oil inlet channel 13 and the oil outlet channel 14; the oil seal component includes a sealing component 2 installed at the bottom of the oil inlet channel 13, an unlocking component 3 installed on the top of the sealing component 2, and a communication component 4 installed inside the oil inlet channel 13 and on the periphery of the unlocking component 3; the sealing component 2 is used to seal the hydraulic oil inside the hydraulic cylinder when the hydraulic cylinder stops telescoping, and the communication component 4 is used to actively unlock the sealing component 2 through the unlocking component 3 when the hydraulic oil enters and exits the oil inlet channel 13, so that the hydraulic oil communicates with the inside of the cylinder block 1 to realize the telescoping of the hydraulic cylinder; the sealing component 2 includes a telescopic groove 21 opened in the base of the cylinder block 1, a spring 22 fixedly connected inside the telescopic groove 21, a sealing column 23 fixedly connected to one side of the spring 22, and a communication hole 24 opened on the side of the telescopic groove 21 away from the spring 22.

[0037] Specifically, when the hydraulic cylinder is in use, the expansion and contraction of the hydraulic cylinder are controlled by controlling the inflow and outflow of hydraulic oil on both sides. When hydraulic oil enters through the oil inlet passage 13, the oil outlet passage 14 discharges hydraulic oil. When the oil inlet passage 13 discharges hydraulic oil, the oil outlet passage 14 inputs hydraulic oil, realizing the bidirectional movement of the piston rod 11 inside the hydraulic cylinder, thereby achieving the lifting effect. When the hydraulic cylinder is lifted, hydraulic oil is continuously pressed into the oil inlet passage 13. The hydraulic oil pushes the unlocking assembly 3 to move downward along the oil inlet passage 13. At this time, the unlocking assembly 3 squeezes the sealing column 23, and the sealing column 23 compresses the compression spring 22 and moves into the telescopic groove 21, causing the communication hole 24 to be opened. At the same time, the communication assembly 4 connects the hydraulic oil on both sides of the unlocking assembly 3, enabling the hydraulic oil to continuously enter the inside of the hydraulic rod through the communication assembly 4 and be connected to the hydraulic oil inside the hydraulic cylinder. At this time, the hydraulic oil continuously pushes the piston rod 11 to lift it. When the hydraulic oil is no longer continuously pressed into the oil inlet passage 13, that is, the unlocking assembly 3 no longer receives continuous extrusion force, the spring 22 resets, driving the sealing column 23 to reset. The reset of the sealing column 23 drives the unlocking assembly 3 to reset. At this time, the sealing column 23 separates the hydraulic oil inside the cylinder block 1 from the hydraulic oil inside the oil inlet passage 13, enabling the hydraulic oil inside the cylinder block 1 to be sealed, achieving automatic sealing of the oil circuit and forming a rigid locking state, avoiding pressure attenuation caused by valve internal leakage, pipeline penetration, or seal aging, ensuring that the hydraulic cylinder can accurately maintain the current position for a long time, significantly improving the position accuracy, effectively eliminating the "position drift" problem, and improving the safety and accuracy of the operation. And the entire oil seal component is composed of a sealing assembly 2, an unlocking assembly 3, and a communication assembly 4, with a relatively simple structure. A simple structure means fewer components and a clearer working principle, reducing the probability of failures and facilitating daily maintenance and repair. For the outdoor use environment, a simple structure is more adaptable to harsh working conditions and reduces the risk of failures caused by complex structures.

[0038] Referring to Figure 5 , one side of the sealing column 23 is frustum-shaped.

[0039] Specifically, when the sealing column 23 is opened by the unlocking assembly 3, the hydraulic oil can flow from the frustum-shaped side, enabling the hydraulic oil on both sides of the sealing column 23 to be quickly connected, so that the lifting force of the hydraulic cylinder can be kept stable.

[0040] Embodiment 2, referring to Figure 3 and Figures 4-6 , this is the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the unlocking assembly 3 includes a moving disk 31 slidably connected in the oil inlet passage 13, a connecting rod 32 fixedly connected to the bottom of the moving disk 31, a groove 33 opened at the top of one side of the sealing column 23, two triangular blocks 34 fixedly connected in the groove 33, and two lower pressing rods 35 and two upper pulling rods 36 fixedly connected to the bottom of the connecting rod 32 in sequence and symmetrically.

[0041] Specifically, when jacking is required, hydraulic oil is pressed into the oil inlet passage 13. Since the moving disk 31 blocks the oil inlet passage 13, the hydraulic disk is squeezed and moved. At this time, the connecting rod 32 moves downward, driving the lower pressing rod 35 to squeeze the top of the triangular block 34, causing the sealing column 23 to move into the telescopic groove 21 by extrusion, thereby opening the communication hole 24, enabling the hydraulic oil to quickly enter the inside of the cylinder block 1 and pushing the piston rod 11 to jack up. When the piston rod 11 needs to be lowered and shortened, at this time, the hydraulic oil in the oil inlet passage 13 is pumped away, causing the moving disk 31 to be driven upward. The upper pull rod 36 squeezes the bottom of the triangular block 34, causing the sealing part to also move into the telescopic groove 21, opening the communication hole 24, unlocking the sealing assembly 2, enabling the hydraulic oil inside the cylinder block 1 to be continuously and smoothly pumped away, and enabling the piston rod 11 to be quickly lowered and shortened. This precise control method ensures the smooth flow of hydraulic oil, and thus realizes the flexible movement of the piston rod 11, which can adapt to different working scenarios and operation requirements. Moreover, the smooth and efficient unlocking process helps to improve the stability of the movement of the piston rod 11 and reduce the jamming and impact phenomena during the movement process. This is of great significance for ensuring the safety and accuracy of outdoor operations. For example, during the lifting and lowering process of an aerial work platform, stable movement can avoid platform shaking and ensure the safety of operators.

[0042] Refer to Figure 6 , in the initial state, the lower pressing rod 35 and the upper pull rod 36 are respectively in contact with both sides of the triangular block 34.

[0043] Specifically, such a design facilitates the upper or lower movement of the moving disk 31, enabling the upper pull rod 36 and the lower pressing rod 35 to quickly squeeze the triangular block 34, thereby quickly opening the sealing column 23. The design of the triangular block 34 enables the forces exerted by the lower pressing rod 35 and the upper pull rod 36 to be effectively converted into the force that pushes the sealing column 23 to move into the telescopic groove 21, and the force transmission efficiency is high. This ingenious force transmission method ensures that the sealing assembly 2 can be unlocked with a relatively small force under different working conditions, reduces the requirements for the pressure of hydraulic oil, and reduces energy loss.

[0044] Refer to Figure 3 , the connecting rod 32 is located on one side of the center position of the moving disk 31.

[0045] Specifically, it is convenient for the moving disk 31 to move downward, and the connecting rod 32 drives the lower pressing rod 35 and the upper pull rod 36 to squeeze the sealing column 23 to move, realizing the quick opening of the communication hole 24.

[0046] Refer to Figures 3-4 , the communication component 4 includes a plurality of upper communication grooves 41 uniformly opened on one side of the oil inlet passage 13, and a plurality of lower communication grooves 42 uniformly opened on the other side of the oil inlet passage 13 and located diagonally below the upper communication grooves 41.

[0047] Specifically, the upper communication groove 41 is used for communication when hydraulic oil enters the oil inlet passage 13, and the lower communication groove 42 facilitates communication when the hydraulic oil in the cylinder block 1 is discharged.

[0048] Referring to Figure 3 , in the initial state, the moving disk 31 is located between the upper communication groove 41 and the lower communication groove 42, and simultaneously closes the upper communication groove 41 and the lower communication groove 42.

[0049] Specifically, when the hydraulic oil enters from the oil inlet passage 13, it pushes the moving disk 31 downward, so that the upper communication groove 41 is opened and communicated with the communication hole 24. When the hydraulic oil in the cylinder block 1 is discharged from the oil inlet passage 13, the moving disk 31 moves upward, so that the lower communication groove 42 is communicated with the communication hole 24, enabling the hydraulic oil to be discharged.

[0050] Referring to Figure 3 , both the upper communication groove 41 and the lower communication groove 42 are arc-shaped.

[0051] Specifically, it facilitates the entry and flow of hydraulic oil. The remaining structure is the same as that of Embodiment 1.

[0052] Embodiment 3, referring to Figures 7-8 , is the third embodiment of the present invention. The difference between this embodiment and the second embodiment is that: on the inner side of the cylinder head 12, there are two-way symmetric spiral grooves 5, and inclined chip discharge holes 6 are respectively opened at the intersections of the two spiral grooves 5. A micro-spring 22 type one-way valve can be arranged inside the chip discharge hole 6, and its opening pressure is only 0.05 MPa, ensuring that impurity particles (along with the external fluid) can be discharged unidirectionally; when it is in the closed state, when the external pressure (atmospheric pressure) is higher than the inside of the chip discharge hole 6, the one-way valve automatically closes to prevent seawater and moisture from flowing back.

[0053] Specifically, the spiral groove 5 is distributed along the circumference of the inner side of the cylinder head 12, and adopts a "half circle clockwise + half circle counterclockwise" symmetrical design (each occupying 180° of the circumference), forming a bidirectional spiral flow channel, and forming a 0.1-0.2mm gap with the surface of the piston rod 11. When the piston rod 11 moves at a speed V, the fluid layer close to the surface of the piston rod 11 is driven to move at a speed of approximately V due to the viscosity, while the inner wall of the spiral groove 5 is stationary, resulting in a velocity gradient in the gap. Since the gap is extremely small and the Reynolds number of the fluid (hydraulic oil or external invading seawater, impurity mixture) is low (Re<2000), the flow is in a laminar state, and the shear flow exhibits a stable velocity distribution (high velocity near the surface of the piston rod 11, low velocity near the groove wall), forming a directional friction force to drive the particle movement. The helix angle of the spiral groove 5 (the angle with the axis of the piston rod 11, usually designed to be 45°-60°) allows the fluid to flow in the axial direction (the direction of movement of the piston rod 11) while being constrained by the groove wall to produce a circumferential component velocity. The two are combined to form a spiral flow trajectory, so that the particles are affected by the centrifugal force in the spiral flow, migrate to the outside of the spiral groove 5 (towards the chip removal hole 6), and are discharged through the one-way valve. This design uses the shear flow and centrifugal force during the reciprocating motion of the piston rod 11 to actively discharge impurities that invade from the outside, and prevent impurities from entering the hydraulic oil and causing wear and failure inside the hydraulic cylinder. The remaining structure is the same as that of Example 2.

[0054] Based on the embodiments 1-3, the working principle of the present invention is as follows: when the oil is supplied, the hydraulic oil pushes the unlocking assembly 3 downward, squeezes the truncated cone-shaped sealing column 23 to compress the spring 22, opens the connecting hole 24 to allow the hydraulic oil to enter the cylinder body 1, and drives the piston rod 11 to lift; when the oil supply stops, the spring 22 is reset, and the sealing column 23 blocks the oil circuit, forming a rigid lock to avoid pressure decay and position drift. The unlocking assembly 3 and the sealing assembly 2 are linked, and through the cooperation of the lower pressing rod 35 and the upper pulling rod 36 with the sealing column 23 and the triangular block 34, the lower pressing rod 35 squeezes the top of the triangular block 34 when lifting, and the upper pulling rod 36 squeezes the bottom of the triangular block 34 when descending, and the connecting hole 24 is unlocked efficiently in both directions, with high force transmission efficiency and stable movement, reducing jamming and impact. In addition, a two-way symmetrical spiral groove 5 and a one-way valve for the chip removal hole 6 are added to the inner side of the cylinder head 12. When the piston rod 11 moves, the shear flow and centrifugal force in the spiral groove 5 drive the external impurities to migrate along the spiral track to the chip removal hole 6, and are discharged through the one-way valve opened at a low pressure of 0.05MPa, while preventing the backflow of seawater moisture and protecting the hydraulic system from impurity wear. The three-level design works synergistically to achieve the multiple functions of "smooth oil circuit connection during extension and retraction, rigid sealing lock when stopped, and automatic impurity discharge during operation", which significantly improves the reliability and service life under complex outdoor conditions.

[0055] Example 4, reference Figure 9, which is the fourth embodiment of the present invention, provides a hydraulic lifting roll-on / roll-off connection bridge, including a carrier plate 7 and a cylinder body 1 installed on the carrier plate 7 for lifting the carrier plate 7. The telescopic movement of the piston rod 11 is controlled by pumping hydraulic oil into the cylinder body 1, thereby realizing the lifting of the carrier plate 7.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A safety hydraulic cylinder for outdoor use, comprising a cylinder block (1), a piston rod (11) disposed within the cylinder block (1), a cylinder head (12) disposed at the top of the cylinder block (1), an oil inlet passage (13) and an oil outlet passage (14) disposed on both sides of the cylinder block (1), characterized in that: It also includes oil seal components respectively arranged inside the oil inlet passage (13) and the oil outlet passage (14); The oil seal component includes a sealing assembly (2) arranged at the bottom of the oil inlet passage (13), an unlocking assembly (3) arranged on top of the sealing assembly (2), and a connecting assembly (4) arranged inside the oil inlet passage (13) and on the periphery of the unlocking assembly (3); The sealing assembly (2) is used to seal the hydraulic oil in the hydraulic cylinder when the hydraulic cylinder stops telescoping. The connecting assembly (4) is used to actively unlock the sealing assembly (2) through the unlocking assembly (3) when the hydraulic oil enters and exits the oil inlet passage (13), so that the hydraulic oil communicates with the inside of the cylinder body (1) to realize the telescoping of the hydraulic cylinder; The sealing assembly (2) includes a telescopic groove (21) opened in the base of the cylinder body (1), a spring (22) arranged in the telescopic groove (21), a sealing column (23) arranged on one side of the spring (22), and a communication hole (24) opened on the side of the telescopic groove (21) away from the spring (22); One side of the sealing column (23) is frustum-shaped; The unlocking assembly (3) includes a moving disk (31) arranged in the oil inlet passage (13), a connecting rod (32) arranged at the bottom of the moving disk (31), a groove (33) opened at the top of one side of the sealing column (23), two triangular blocks (34) arranged in the groove (33), and two lower pressing rods (35) and two upper pulling rods (36) symmetrically arranged at the bottom of the connecting rod (32) in sequence; 2. The safety hydraulic cylinder for outdoor use according to claim 1, wherein: In the initial state, the lower pressing rod (35) and the upper pulling rod (36) are respectively in contact with both sides of the triangular block (34).

3. The safety hydraulic cylinder for outdoor use according to claim 1, wherein: The connecting rod (32) is located on one side of the center position of the moving disk (31).

4. The safety hydraulic cylinder for outdoor use according to claim 1, wherein: The connecting assembly (4) includes a plurality of upper connecting grooves (41) uniformly opened on one side of the oil inlet passage (13), and a plurality of lower connecting grooves (42) uniformly opened on the other side of the oil inlet passage (13) and obliquely below the upper connecting grooves (41); 5. The safety hydraulic cylinder for outdoor use according to claim 4, wherein: In the initial state, the moving disk (31) is located between the upper connecting groove (41) and the lower connecting groove (42) and closes both the upper connecting groove (41) and the lower connecting groove (42) at the same time.

6. The safety hydraulic cylinder for outdoor use according to claim 5, characterized in that: Both the upper connecting groove (41) and the lower connecting groove (42) are arc-shaped.

7. The safety hydraulic cylinder for outdoor use according to claim 1, wherein: On the inner side of the cylinder head (12), a bidirectional symmetric spiral groove (5) is opened, and inclined chip discharging holes (6) are respectively opened at the intersection of the two spiral grooves (5).

8. A hydraulic lifting roll-on / roll-off connection bridge, which adopts the outdoor-use safety hydraulic cylinder as described in Claim 1, is characterized in that: It includes a carrier plate (7) and a cylinder body (1) arranged on the carrier plate (7) for lifting the carrier plate (7).

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