Full extension mechanical self-locking lift cylinder

Abstract

The present application relates to the technical field of lifting oil cylinder, in particular to a full extension mechanical self-locking lifting oil cylinder, which comprises a cylinder barrel, the open end of the cylinder barrel is detachably connected with a cylinder head, the outer surface of the cylinder head is detachably connected with a self-locking cover, the inside of the cylinder barrel is movably connected with a piston, the shaft center of the piston is coaxially fixedly connected with a cylinder rod, the cylinder rod movably penetrates the center holes of the cylinder head and the self-locking cover, the inside of the self-locking cover is movably connected with a locking round head, the surface of the cylinder rod is provided with a locking round groove for embedding the locking round head, and the locking round head locks the cylinder rod by embedding the locking round groove, the purpose of the present application is to solve the problem that the traditional lifting oil cylinder mainly relies on the continuous pressure of the hydraulic system to maintain the supporting state, when the hydraulic system appears aging of sealing element, damage of pipeline and other conditions, the hydraulic oil is prone to leakage, which causes the cylinder rod to fall back due to the load of self weight, and causes the equipment to lose control or safety hazards.

Description

Technical Field

[0001] This invention relates to the field of lifting cylinder technology, specifically a fully extended mechanical self-locking lifting cylinder. Background Technology

[0002] As a key actuator in the field of mechanical engineering, the lifting cylinder consists of a cylinder barrel, piston rod, piston assembly, and sealing device. It achieves precise lifting operations through the pressure transmission of the hydraulic system. The working principle of this device is based on Pascal's law. When the hydraulic pump injects high-pressure oil into the cylinder barrel, the pressure acts on the piston surface, pushing the piston rod to make linear reciprocating motion, thereby converting hydraulic energy into mechanical energy to complete the vertical lifting or lowering operation of the load. Its significant advantages are that it can provide stable lifting force, with a load capacity ranging from hundreds of kilograms to tens of tons, and the lifting speed and positioning accuracy can be precisely adjusted through the control valve group.

[0003] In the field of construction machinery, lifting cylinders are core functional components of equipment such as loaders, excavators, and cranes. For example, the boom lifting system of a loader relies on cylinders to load and unload materials, and the luffing mechanism of a crane adjusts the boom angle through cylinders to adapt to different lifting needs. In industrial equipment applications, lifting cylinders are widely used in lifting platforms of automated production lines, mold lifting devices in mold manufacturing, and rack loading and unloading equipment in warehousing and logistics. They can meet the requirements of high-precision positioning and frequent start-stop operations. By selecting high-strength materials and special surface treatment processes, they can effectively resist the effects of complex working conditions such as dust, moisture, and heavy loads. Therefore, they play an irreplaceable role in heavy equipment in industries such as metallurgy, chemical industry, and construction.

[0004] The working mechanism of traditional lifting cylinders relies on the dynamic balance of the hydraulic system. The maintenance of its support state is essentially a continuous coupling process of hydraulic energy and mechanical energy. After the cylinder completes the lifting action, a constant pressure difference needs to be formed on both sides of the piston through the pressure holding circuit to counteract the load weight. However, this design that relies on continuous hydraulic support will cause the sealing lip to wear or deform due to material aging under long-term high-pressure conditions. Metal pipelines may also develop cracks due to vibration fatigue and corrosion, especially at joint welding points or areas of stress concentration at bends, which are prone to leakage. When hydraulic oil leakage occurs, the pressure in the upper or lower chamber of the cylinder will gradually decrease as the leakage accumulates, breaking the original pressure balance. This failure mode is particularly dangerous in scenarios such as aerial work platforms for construction machinery and luffing mechanisms of truck cranes. The boom may fall rapidly due to its own weight, causing the cargo to fall or the equipment to overturn. The failure of the cylinder seal in industrial lifting platforms may cause the platform to suddenly sink, threatening the safety of the operators. Summary of the Invention

[0005] The purpose of this invention is to provide a fully extendable mechanical self-locking lifting cylinder to solve the problem that traditional lifting cylinders mainly rely on the continuous pressure of the hydraulic system to maintain the support state. When the hydraulic system experiences issues such as aging seals or damaged pipelines, hydraulic oil leakage is likely to occur, causing the cylinder rod to fall back due to its own weight, leading to equipment malfunction or safety hazards.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A fully extendable mechanical self-locking lifting cylinder includes a cylinder barrel, a cylinder head detachably connected to the open end of the cylinder barrel, a self-locking cover detachably connected to the outer surface of the cylinder head, a piston movably connected inside the cylinder barrel, a cylinder rod coaxially fixedly connected to the axis of the piston, the cylinder rod movably passing through the central hole of the cylinder head and the self-locking cover, a locking round head movably connected inside the self-locking cover, and a locking round groove for the locking round head to be inserted into the surface of the cylinder rod, the locking round head locking the cylinder rod by being inserted into the locking round groove.

[0008] Preferably, a connecting sleeve is fitted on the surface of the cylinder rod, the connecting sleeve is located inside the cylinder barrel, and a plugging head is movably connected to the surface of the connecting sleeve, the plugging head being used to seal the locking groove.

[0009] Preferably, the surface of the connecting sleeve is provided with a channel for the movement of the blocking round head, and the channel is in communication with the inner cavity of the cylinder.

[0010] Preferably, a retaining ring is fixedly connected to the inner surface of the cylinder head, and an annular gap with a width matching the thickness of the connecting sleeve is formed between the retaining ring and the outer wall of the cylinder rod.

[0011] Preferably, a limit support rod is fixedly connected to the surface of the retaining ring, and its axial extension direction is parallel to the cylinder rod axis.

[0012] Preferably, the bottom end of the locking head is provided with an annular oil storage groove.

[0013] Preferably, a limit stop ring is fixedly connected to the opening of the connecting sleeve channel.

[0014] Preferably, a threaded sleeve is rotatably connected to the surface of the self-locking cover, and a threaded rod is rotatably connected to one end of the locking round head. The threaded sleeve is coaxially threaded onto the surface of the threaded rod.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. By rigidly engaging the locking round head with the locking round groove, mechanical locking is achieved in the fully extended state of the cylinder, replacing simple hydraulic support. Even if there is leakage, pressure fluctuation or external impact in the hydraulic system, the cylinder rod can still be prevented from falling back, ensuring the stability of the load position and avoiding safety accidents.

[0017] 2. When the cylinder rod retracts, the plugging round head automatically engages with the locking round groove under the pressure of hydraulic oil, preventing hydraulic oil from entering the groove and avoiding oil residue when it extends again, which would increase the engagement resistance of the locking round head or cause the locking to fail, thus ensuring the rigid engagement of the mechanical lock.

[0018] 3. The gap ring prevents high-pressure oil from entering the gap between the connecting sleeve and the cylinder head, ensuring that the connecting sleeve is always in close contact with the cylinder head end face, avoiding free sliding that could cause misalignment between the blockage round head and the locking round groove, and ensuring dynamic sealing and alignment accuracy during the shrinkage process;

[0019] 4. Limiting the piston stroke with a limiting strut prevents it from moving too far to the left, which would result in an insufficient volume of the oil chamber on the left side. This provides sufficient space for the hydraulic pressure to act on the plugging head, ensuring the normal operation of the hydraulic system.

[0020] 5. The annular oil reservoir at the bottom of the locking head can temporarily store a small amount of hydraulic oil remaining in the locking groove, preventing the oil from forming a high-pressure oil film that hinders mechanical locking, allowing the residual oil to be processed after operation, and improving the system's fault tolerance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall cylinder rod extension state of the present invention;

[0022] Figure 2 This is a vertical cross-sectional structural diagram of the overall cylinder barrel, cylinder head, and self-locking cover of the present invention;

[0023] Figure 3 This is a cross-sectional front view of the entire cylinder rod of the present invention in the extended state;

[0024] Figure 4 For the present invention Figure 3 Enlarged view of point A in the middle;

[0025] Figure 5 For the present invention Figure 3 Enlarged view of point B in the middle;

[0026] Figure 6 This is a schematic diagram of the cylinder rod structure of the present invention;

[0027] Figure 7 This is a schematic diagram of the structure of the retaining ring of the present invention;

[0028] Figure 8 This is a schematic diagram of the vertical section of the connecting sleeve of the present invention;

[0029] Figure 9 This is a schematic diagram of the vertical section of the locking round head structure of the present invention;

[0030] Figure 10 This is a cross-sectional front view of the overall cylinder rod in its retracted state according to the present invention.

[0031] In the diagram: 1. Cylinder barrel; 2. Cylinder head; 3. Self-locking cover; 4. Piston; 5. Cylinder rod; 6. Locking groove; 7. Plug head; 8. Limiting ring; 9. Connecting sleeve; 10. Seam retainer ring; 11. Limiting strut; 12. Locking head; 13. Annular oil reservoir groove; 14. Threaded rod; 15. Threaded sleeve; 16. First gear; 17. Second gear; 18. Motor. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figures 1 to 10 This invention provides a technical solution: a fully extendable mechanical self-locking lifting cylinder, comprising a cylinder barrel 1, a cylinder head 2 detachably connected to the open end of the cylinder barrel 1, a self-locking cover 3 detachably connected to the outer surface of the cylinder head 2, both the cylinder head 2 and the self-locking cover 3 being detachably connected by bolts, a piston 4 movably connected inside the cylinder barrel 1, a cylinder rod 5 coaxially fixedly connected at the axis of the piston 4, the cylinder rod 5 movably passing through the central hole of the cylinder head 2 and the self-locking cover 3, a locking round head 12 movably connected inside the self-locking cover 3, and a locking round groove 6 for the locking round head 12 to be inserted into the surface of the cylinder rod 5. The locking groove 6 locks the cylinder rod 5. When the cylinder rod 5 extends out of the cylinder barrel 1, if the locking groove 6 moves to align with the locking head 12, the cylinder rod 5 can be mechanically locked by pushing the locking head 12 into the locking groove 6. The mechanical locking structure replaces the simple hydraulic support, and rigid fixation can be achieved in the fully extended state of the cylinder. The mechanical self-locking function can serve as a double insurance for the hydraulic system, preventing the cylinder rod 5 from falling back due to hydraulic system leakage, pressure fluctuations, or external impacts, ensuring the stability of the load position. After locking, the hydraulic system can be unloaded, reducing the long-term pressure loss of the oil pump, extending the life of hydraulic components, and reducing energy consumption.

[0034] A connecting sleeve 9 is fitted onto the surface of the cylinder rod 5. The connecting sleeve 9 is located inside the cylinder barrel 1. A plugging head 7 is movably connected to the surface of the connecting sleeve 9. The plugging head 7 is used to seal the locking groove 6. When the cylinder rod 5 retracts, the locking groove 6 moves into the cylinder barrel 1 along with the cylinder rod 5. Before entering the cylinder barrel 1, the locking groove 6 passes through the connecting sleeve 9. When the locking groove 6 is aligned with the plugging head 7, the plugging head 7 will embed into the locking groove 6 due to the force, thus blocking the locking groove 6. This structure can prevent the hydraulic oil in the cylinder barrel 1 from entering the locking groove 6 when the locking groove 6 moves into the cylinder barrel 1 along with the cylinder rod 5. This ensures that when the cylinder rod 5 extends again and the locking groove 6 is aligned with the locking head 12, there is no oil in the groove, so that the locking head 12 can be reliably embedded in the groove. This avoids the locking head 12 and the locking groove 6 from having increased embedding resistance and locking failure due to the presence of oil.

[0035] The surface of the connecting sleeve 9 has a channel for the movement of the plugging head 7. The channel is connected to the inner cavity of the cylinder 1, so that the non-embedded end of the plugging head 7 is exposed in the hydraulic oil of the cylinder 1. The head can be embedded in the locking groove 6 on the surface of the cylinder rod 5. When the cylinder 1 is full of hydraulic oil, the oil pressure acts on the tail end face of the plugging head 7. When the cylinder rod 5 retracts and moves the locking groove 6 to align with the plugging head 7, the plugging head 7 automatically embeds into the locking groove 6 under hydraulic pressure, forming a seal. The tail of the plugging head 7 is subjected to the hydraulic oil pressure in the cylinder 1, and always maintains a thrust in the direction of the cylinder rod 5 axis, and makes the connecting sleeve 9 move together with the cylinder rod 5 in the cylinder 1. This ensures that when the locking groove 6 is in the cylinder 1, the plugging head 7 always blocks the locking groove 6. No manual operation or additional spring mechanism is required. The automatic embedding of the plugging head 7 is achieved by the system's own oil pressure, reducing mechanical complexity.

[0036] When the cylinder rod 5 needs to extend, high-pressure oil is injected into the oil chamber on the right side of the piston 4, and the oil chamber on the left side is depressurized. Under the action of pressure difference, the piston 4 drives the cylinder rod 5 to move to the left. The connecting sleeve 9 moves synchronously with the cylinder rod 5 until the left end surface of the connecting sleeve 9 abuts against the right end surface of the cylinder head 2. At this time, the oil pressure in the oil chamber on the left side of the piston 4 is further reduced, so that the hydraulic pressure acting on the tail of the plug round head 7 is reduced. The bottom of the locking groove 6 is an arc surface with an inclination angle. When the cylinder rod 5 continues to move to the left under the action of continuous oil pressure difference, the inclined surface of the locking groove 6 will generate a radial thrust on the head of the plug round head 7, pressing the plug round head 7 back into the channel of the connecting sleeve 9. At this point, the connecting sleeve 9 stops moving because it abuts against the cylinder head 2, while the cylinder rod 5 continues to extend to the left. When the locking groove 6 passes through the center hole of the cylinder head 2 and moves to be axially aligned with the locking round head 12 in the self-locking cover 3, a signal is applied to the drive mechanism of the locking round head 12 to make it radially embed into the locking groove 6, completing the mechanical locking of the cylinder rod 5 in the fully extended state.

[0037] A retaining ring 10 is fixedly connected to the inner surface of the cylinder head 2. An annular gap with a width matching the thickness of the connecting sleeve 9 is formed between the retaining ring 10 and the outer wall of the cylinder rod 5. When the connecting sleeve 9 moves to the left with the cylinder rod 5 until its left end face is in contact with the right end face of the cylinder head 2, the left side of the connecting sleeve 9 is precisely embedded in the annular gap between the retaining ring 10 and the cylinder rod 5. That is, the left end face of the connecting sleeve 9 is blocked by the retaining ring 10, and the remaining part of the retaining ring 10 is exposed in the left oil chamber of the cylinder barrel 1. By setting the retaining ring 10, when the cylinder rod 5 retracts, high-pressure oil is introduced into the left oil chamber, and the right oil chamber is depressurized. Due to the blocking effect of the retaining ring 10, high-pressure oil cannot enter. The gap between the left end face of the connecting sleeve 9 and the cylinder head 2 can only act on the right side of the connecting sleeve 9, generating pressure to the left, so that the connecting sleeve 9 is always in close contact with the end face of the cylinder head 2. When the cylinder rod 5 retracts to the position where the locking groove 6 is aligned with the plugging head 7, the high pressure oil in the left oil chamber acts on the tail of the plugging head 7 through the channel of the connecting sleeve 9, driving it to embed into the locking groove 6. At this time, the cylinder rod 5 drives the connecting sleeve 9 to move to the right in sync, realizing dynamic sealing during the retraction stroke. In the initial stage of cylinder rod 5 retraction, the connecting sleeve 9 is limited and pressed tightly against the cylinder head 2 to prevent it from sliding freely and causing the plugging head 7 to be unable to easily align with the locking groove 6.

[0038] A limiting support rod 11 is fixedly connected to the surface of the retaining ring 10. Its axial extension direction is parallel to the axis of the cylinder rod 5. By setting the limiting support rod 11, when the piston 4 drives the cylinder rod 5 to move to the left, the piston 4 stops moving when it abuts against the right end of the limiting support rod 11. This prevents the piston 4 from moving too far to the left, which would cause the oil chamber volume on the left side of the piston 4 to be too small. This limiting distance ensures that the oil chamber on the left side of the piston 4 retains sufficient volume, providing an effective hydraulic pressure action space for the plug round head 7.

[0039] An annular oil storage groove 13 is provided at the bottom of the locking round head 12. The annular oil storage groove 13 plays a fault-tolerant role. By providing the annular oil storage groove 13, when a small amount of hydraulic oil remains in the locking round groove 6, the annular oil storage groove 13 can temporarily store the oil during the locking round head 12 insertion process, so as to avoid the formation of a high-pressure oil film between the contact surfaces, which would hinder the rigid engagement of the mechanical lock. The small amount of oil in the locking round groove 6 can be removed after the work is completed.

[0040] The opening of the connecting sleeve 9 channel is fixedly connected to a limiting ring 8, which is used to prevent the blocking round head 7 from moving out of the channel.

[0041] In an embodiment of controlling the movement of the locking round head 12, a threaded sleeve 15 is rotatably connected to the surface of the self-locking cover 3, and a threaded rod 14 is rotatably connected to one end of the locking round head 12. The threaded sleeve 15 is coaxially threaded onto the surface of the threaded rod 14. By controlling the rotation of the threaded sleeve 15, the threaded rod 14 moves axially under the action of the thread, which drives the locking round head 12 to move axially, thereby controlling the locking round head 12 to move deeper or out of the locking round groove 6.

[0042] The locking and unlocking process can be achieved by manually rotating the threaded sleeve 15 or by electrically driving the threaded sleeve 15. In the embodiment of electrically driving the threaded sleeve 15, a motor 18 is fixedly installed on the surface of the self-locking cover 3, and a second gear 17 is coaxially fixedly connected to the output end of the motor 18. A first gear 16 is coaxially fixedly connected to the surface of the threaded sleeve 15. The second gear 17 and the first gear 16 are meshed. By starting the motor 18, the second gear 17 is driven to rotate, the second gear 17 rotates, the first gear 16 rotates, and the threaded sleeve 15 rotates.

[0043] The specific solution is as follows: Initial state: Cylinder rod 5 is in the retracted state, and locking groove 6 is blocked and sealed by round head 7.

[0044] Hydraulic extension: High-pressure oil is injected into the right oil chamber of piston 4, and the left oil chamber is depressurized synchronously. Under the action of oil pressure difference, piston 4 moves to the left, driving cylinder rod 5 to extend synchronously. Connecting sleeve 9 moves together with cylinder rod 5. When the left end surface of connecting sleeve 9 abuts against the right end surface of cylinder head 2, the oil pressure in the right oil chamber continues to increase, and cylinder rod 5 continues to move to the left. At this time, the inclined bottom of locking groove 6 generates radial thrust on blocking head 7, pressing it back into the channel of connecting sleeve 9, releasing the seal on locking groove 6, and cylinder rod 5 continues to extend. When locking groove 6 moves to be axially aligned with locking head 12 in self-locking cover 3, that is, cylinder rod 5 is fully extended, hydraulic oil injection is stopped, and threaded sleeve 15 on self-locking cover 3 is rotated. Through threaded rod 14, locking head 12 is pushed radially into locking groove 6. After locking head 12 is embedded, cylinder rod 5 is rigidly fixed by mechanical structure.

[0045] The cylinder rod 5 retraction process: First, pressurize the hydraulic system to establish oil pressure in the left oil chamber of piston 4. Rotate the threaded sleeve 15 in the opposite direction to make the locking head 12 exit from the locking groove 6 and return to the initial position in the self-locking cover 3. High-pressure oil is introduced into the left oil chamber and the right oil chamber is depressurized. Under the action of oil pressure difference, piston 4 moves to the right, driving cylinder rod 5 to retract synchronously. When the locking groove 6 moves to align with the plugging head 7 in the connecting sleeve 9, the hydraulic pressure in the left oil chamber acts on the tail of the plugging head 7, driving it to embed into the locking groove 6, sealing the space in the groove, and preventing hydraulic oil from entering the groove and affecting the next locking. Subsequently, the connecting sleeve 9 moves together with cylinder rod 5.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fully extended mechanical self-locking lifting cylinder, comprising a cylinder barrel (1), characterized in that: The cylinder (1) is detachably connected to a cylinder head (2) at its open end. A self-locking cover (3) is detachably connected to the outer surface of the cylinder head (2). A piston (4) is movably connected inside the cylinder (1). A cylinder rod (5) is coaxially fixedly connected to the axis of the piston (4). The cylinder rod (5) movably passes through the central hole of the cylinder head (2) and the self-locking cover (3). A locking round head (12) is movably connected inside the self-locking cover (3). A locking round groove (6) is provided on the surface of the cylinder rod (5) for the locking round head (12) to be inserted. The locking round head (12) locks the cylinder rod (5) by being inserted into the locking round groove (6). The cylinder rod (5) is fitted with a connecting sleeve (9), which is located inside the cylinder (1). A plugging head (7) is movably connected to the surface of the connecting sleeve (9), and the plugging head (7) is used to seal the locking groove (6). The surface of the connecting sleeve (9) is provided with a channel for the movement of the blocking head (7), and the channel is connected to the inner cavity of the cylinder (1).

2. The fully extendable mechanical self-locking lifting cylinder according to claim 1, characterized in that, A retaining ring (10) is fixedly connected to the inner surface of the cylinder head (2), and an annular gap with a width matching the thickness of the connecting sleeve (9) is formed between the retaining ring (10) and the outer wall of the cylinder rod (5).

3. A fully extendable mechanical self-locking lifting cylinder according to claim 2, characterized in that, The surface of the retaining ring (10) is fixedly connected to a limiting support rod (11), whose axial extension direction is parallel to the axis of the cylinder rod (5).

4. A fully extendable mechanical self-locking lifting cylinder according to claim 1, characterized in that, The bottom end of the locking head (12) is provided with an annular oil storage groove (13).

5. A fully extendable mechanical self-locking lifting cylinder according to claim 1, characterized in that, The opening of the connecting sleeve (9) channel is fixedly connected to a limit stop ring (8).

6. A fully extendable mechanical self-locking lifting cylinder according to claim 1, characterized in that, The surface of the self-locking cover (3) is rotatably connected to a threaded sleeve (15), and one end of the locking round head (12) is rotatably connected to a threaded rod (14). The threaded sleeve (15) is coaxially threaded onto the surface of the threaded rod (14).

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