Swing oil cylinder

Abstract

The invention relates to the technical field of swing oil cylinders, in particular to a swing oil cylinder which comprises a cylinder body, an end cover and a piston and is further provided with a first locking nut, the first locking nut is fixedly connected with the cylinder body and transmits hydraulic pressure borne by an output shaft body to the cylinder body, and the end cover is fixedly connected with the cylinder body. The counter-acting force of the hydraulic force for pushing the piston to move towards the first cavity is transmitted to the cylinder body, the hydraulic force for pushing the piston to reciprocate does not directly act on the output shaft body under the combined action of the two, and the situation that the counter-acting force of the hydraulic force for pushing the piston to reciprocate is transmitted to the thrust gasket or the needle bearing by the output shaft body is avoided. The thrust gasket or the needle bearing rotates and rubs under the condition that the thrust gasket or the needle bearing bears huge hydraulic pressure and is quickly abraded or damaged, so that a tandem shaft fault is caused, and the service life of a thrust component is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of swing oil cylinders, in particular to a swing oil cylinder. BACKGROUND A swing oil cylinder is a hydraulic actuator that can achieve reciprocating swing motion. Due to its compact structure and large output torque, it plays an important role in various industrial machines and engineering equipment. It drives the internal components to move by the pressure of hydraulic oil, converts hydraulic energy into mechanical energy, and drives the load to complete a specific angle of rotation. The stability and reliability of its performance are directly related to the overall operating efficiency of the equipment. Figure 1 As shown in the existing swing cylinder structure diagram, the main seal 100 and the guide ring 200 are usually arranged in the outer circular groove of the output shaft body 300 and the rear end cover 400. The rear end cover 400 and the output shaft body 300 are fixed and rotated synchronously by spline or threaded pin, and the thrust washer or needle bearing 500 at both ends plays the role of axial positioning and bearing axial force. In the field of aerial work platforms, the swing oil cylinder is the core component for driving the platform basket to rotate. When the aerial work platform is working, it needs to adjust the position of the basket flexibly through the swing oil cylinder to meet the needs of different work points. At this time, the swing oil cylinder not only needs to bear the weight of the platform basket itself and the personnel and tools carried, but also needs to cope with the possible unbalanced load during work, which puts high requirements on its carrying capacity, anti-unbalanced load performance and running stability.

[0002] In the field of quick change of excavator accessory rotation swing, the swing oil cylinder is the core component for driving the excavator accessory to rotate. Due to the frequent occurrence of unpredictable overload, the swing oil cylinder will instantaneously bear a huge bending moment, which puts higher requirements on its bending moment bearing capacity and impact resistance.

[0003] However, the existing swing cylinder structure has obvious disadvantages in the application of partial load. First, the output shaft body 300 is connected with the end cover 400 by locking, and is positioned by the thrust washer 500. The piston 600 reciprocates under the action of hydraulic pressure and is limited by the end face of the output shaft 300 and the end cover 400. When the output shaft body 300 transmits torque, it will be subjected to a large axial force and a counterforce generated by the reciprocating movement of the push piston 600. The axial force and the external partial load bending moment act together, causing the thrust washer or the needle bearing 500 to rotate and rub under a combined load of tens of tons, which leads to rapid wear or rupture. Second, the partial load causes the guide ring 200 to be eccentrically worn on one side, which causes the output shaft body 300 to move eccentrically, increases the dynamic gap at the main seal 100, and causes the seal lip to be squeezed into the gap by high-pressure oil, resulting in shear damage and leakage failure. In addition, the traditional structure sets the seal on the output shaft body 300. In order to avoid the wear failure between the output shaft body 300 and the cylinder body 700, a larger seal extrusion gap (usually more than 0.2 mm) is designed, which further increases the risk of seal extrusion, resulting in a high failure rate and short service life of the traditional swing cylinder under partial load. SUMMARY

[0004] To solve the above problems, the application provides a swing cylinder, comprising: a cylinder body, the cylinder body is provided with a channel extending in the axial direction thereof; an output shaft body, at least a part of the output shaft body extends into the channel of the cylinder body, and a piston channel is formed between the output shaft body and the cylinder body; an end cover, the end cover is located at one end of the cylinder body and is used for closing the end of the piston channel; a piston, the piston is located in the piston channel, the outer wall of the piston is provided with external helical teeth, the internal helical teeth of the inner wall of the cylinder body are engaged to form a helical transmission pair, and the piston divides the piston channel into a first chamber and a second chamber; the cylinder body is provided with a first oil inlet hole communicating with the first chamber and a second oil inlet hole communicating with the second chamber; a first locking nut is further provided, and the first locking nut and the end cover are fixedly arranged on the inner wall of the cylinder body.

[0005] In one embodiment, the inner wall of the piston is provided with internal spline teeth, the output shaft body and the internal spline teeth of the piston form a spline engagement transmission pair, and the spline engagement transmission pair is a helical tooth transmission or a straight tooth transmission.

[0006] In one embodiment, the spline engagement transmission pair is a straight tooth spline engagement transmission pair.

[0007] In one of the embodiments, the output shaft body comprises an output shaft and an inner shaft, the inner shaft is provided with an outer straight toothed spline, which is engaged with the inner straight toothed spline of the inner wall of the piston to form a first straight toothed spline engagement transmission pair; the inner shaft is provided with an inner straight toothed spline, and the output shaft is provided with an outer straight toothed spline, the outer straight toothed spline on the output shaft is engaged with the inner straight toothed spline on the inner shaft to form a second straight toothed spline engagement transmission pair, the output shaft is provided with an output shaft positioning step, the inner shaft is provided with an inner shaft positioning step, and the output shaft is in abutting fit with the inner shaft.

[0008] In one of the embodiments, the inner shaft is provided with a locking positioning step, the first locking nut is located at the locking positioning step, the first locking nut is located between the inner shaft and the output shaft, the first locking nut is made of wear-resistant ductile cast iron material and is lubricated by wear-resistant grease.

[0009] In one of the embodiments, a second locking nut is further provided, the second locking nut is arranged on the output shaft body, the second locking nut is located close to the end cover side, the second locking nut is connected through the threaded connection of the shaft head on the output shaft, and is fixed by a threaded pin after being tightened, and rotates synchronously with the output shaft.

[0010] In one of the embodiments, the inner shaft is provided with a first shaft load element, the first shaft load element is a thrust washer or a needle bearing, and the first shaft load element is located between the bearing positioning step of the inner shaft and the positioning step of the cylinder body; the bearing positioning step is an annular shaft shoulder, which forms axial limiting for the first shaft load element; the first locking nut is located outside the first shaft load element, which forms locking positioning for the first shaft load element and can adjust the gap therebetween.

[0011] In one of the embodiments, the end cover is provided with an outer thread which is matched with the inner thread of the cylinder body to fix the end cover on the cylinder body, the end cover is provided with a bearing mounting position, the bearing mounting position is provided with a second shaft load element, the second shaft load element is a thrust washer or a needle bearing, and the second shaft load element is located between the end cover and the second locking nut; one side of the second shaft load element is in contact with the end face of the bearing mounting position of the end cover, and the other side is in contact with the end face of the second locking nut.

[0012] In one of the embodiments, the power output end of the output shaft is provided with a first guide ring, the outer ring of the first guide ring is matched with the inner wall of the cylinder body, the inner ring of the first guide ring is matched with the outer wall of the output shaft, and is radially distributed between the output shaft and the cylinder body; the end cover is provided with a guide ring mounting position, the second guide ring is arranged in the guide ring mounting position, the outer ring of the second guide ring is matched with the inner wall of the end cover, the inner ring of the second guide ring is matched with the outer wall of the second locking nut, and is radially distributed between the second locking nut and the end cover; the first guide ring and the second guide ring are both iron-based oil-free lubricated bushings.

[0013] In one of the embodiments, a plurality of sealing assemblies are further arranged, the first main seal is arranged between the inner shaft and the cylinder body, is arranged in the sealing groove of the cylinder body, and is in close contact with the outer wall of the inner shaft; the shaft static seal is arranged between the output shaft and the inner shaft, is arranged in the sealing groove of the inner shaft; the second main seal is arranged between the end cover and the cylinder body, is arranged in the sealing groove of the end cover, the shaft rotary dynamic seal is arranged between the end cover and the output shaft, is arranged in the sealing groove of the end cover, and is in close contact with the outer wall of the output shaft.

[0014] In one of the embodiments, the second straight tooth spline meshing transmission pair is a small modulus and large tooth number structure, and the rotation starting point of the output shaft can be adjusted by changing the meshing tooth position of the output shaft and the inner shaft.

[0015] In one of the embodiments, the inner helical tooth of the inner wall of the cylinder body can be integrally formed with the cylinder body, or can be fixedly arranged on the passage inner wall of the cylinder body by using a separately processed inner tooth fixing piece; the first piston sealing piece for sealing hydraulic oil is arranged between the piston and the cylinder body, the second piston sealing piece for sealing hydraulic oil is arranged between the piston and the output shaft body, and the first piston sealing piece and the second piston sealing piece can be located on the same side of the piston or can be respectively located on the two sides of the piston.

[0016] In one of the embodiments, the output shaft can be designed as an integrated output shaft or a split output shaft; the split output shaft is split into a sealing section extending into the piston passage and an output section for power output from the side away from the power output end of the output shaft; the sealing section is matched with the piston to realize sealing; the output section of the output shaft can be a flange with a threaded hole or can be an adapter suitable for connecting various regular and irregular geometric bodies in one or more connection modes such as spline output, key output and square key output.

[0017] The application has the following beneficial effects: This application provides a swing cylinder. A first locking nut is fixedly connected to the cylinder body. When the piston moves towards the second chamber, the hydraulic pressure borne by the output shaft body is transmitted to the cylinder body through the first locking nut. An end cover is fixedly connected to the cylinder body. When the piston moves towards the first chamber, the hydraulic pressure borne by the output shaft body is transmitted to the cylinder body through the end cover. The combined effect of these two components prevents the hydraulic pressure driving the piston reciprocating from directly acting on the output shaft body. This avoids the output shaft body transmitting the reaction force of the hydraulic pressure driving the piston reciprocating to the thrust washer or needle roller bearing, thus reducing the thrust... Under immense hydraulic pressure, the gaskets or needle roller bearings experience rapid wear or failure due to rotational friction, leading to shaft failure and extending the service life of the thrust components. The first locking nut and the output shaft body end face are engaged with the cylinder positioning step via the first shaft load element. Combined with the external guide ring, these two elements significantly improve the overall structure's resistance to eccentric bending moments, preventing seal failure due to increased extrusion gap caused by eccentric loading. This further enhances the sealing reliability of the swing cylinder, reduces oil leakage, and ensures long-term stable operation. The swing cylinder of this application is particularly suitable for aerial work platforms and excavator attachment rotation applications. Its core advantage lies in the dual optimization of structural and stress design. The first locking nut is fixedly connected to the cylinder body, and the end cover is also fixedly connected to the cylinder body. Together, they transmit the hydraulic pressure and reaction force driving the piston's reciprocating motion to the cylinder body, preventing axial force impact on the thrust components. Furthermore, the external guide ring further enhances the overall structure's resistance to eccentric bending moments, ensuring stable operation of the cylinder under eccentric loading conditions. Based on this, the spur spline meshing transmission pair formed by the spur spline inside the piston wall and the output shaft body only transmits torque without axial force, so that the output shaft body only bears the static load of the platform. The spur design eliminates axial force. When filled with oil or under off-center load, the shaft load element is only subjected to the static load of the platform and there is no hydraulic impact force, which greatly reduces the risk of wear, ensures stable operation, extends service life, and meets the high requirements of equipment reliability in this field.

[0018] The split design of the inner shaft and output shaft, through a two-stage spur spline pair series transmission combined with end face stop positioning, achieves functional separation and anti-interference optimization. The precision sealing fit between the inner shaft and the cylinder block allows for individual dimensional optimization for high-pressure sealing, effectively isolating the external off-center load and bending moment on the output shaft from interference with the sealing system. The slight clearance (e.g., 0.1mm) in the spline meshing provides adaptive buffer space when the output shaft is subjected to external force eccentricity, preventing damage to the inner shaft and cylinder block seals due to rigid interference. At the same time, the output shaft can be flexibly disassembled or replaced as an independent module. The output shaft can be a flange with threaded holes or an adapter, adapting to various regular and irregular geometric connection methods, such as one or more of spline output, flat key output, and square key output, greatly improving the product's adaptability to operating conditions, ease of maintenance, and functional expandability. Attached Figure Description Figure 1 This is a schematic diagram of the existing technology structure; Figure 2 This is a schematic diagram of the structure of this application; Figure 3 This is a schematic diagram of the split structure of the output shaft main body of this application; Figure 4 This is a schematic diagram of the split structure of the output shaft in this application; Figure 5 A schematic diagram showing the piston seals located on both sides of the piston. Explanation of symbols in the diagram: 100. Main seal; 200. Guide ring; 300. Output shaft; 400. Rear end cover; 500. Thrust washer or needle roller bearing; 600. Piston; 700. Cylinder block; 1. Cylinder block; 11. First oil inlet; 12. Second oil inlet; 2. Output shaft body; 21. Output shaft; 22. Inner shaft; 221. Locking and positioning step; 222. Bearing positioning step; 23. First locking nut; 24. Second locking nut; 25. First shaft load element; 26. Second shaft load element; 27. First guide ring; 28. Second guide ring; 3. Piston passage; 31. First chamber; 32. Second chamber; 4. End caps; 5. Piston; 6. Screw drive pair; 7. Spline meshing transmission pair; 71. First spur spline meshing transmission pair; 72. Second spur spline meshing transmission pair; 81. First main seal; 82. Static seal for shaft; 83. Second main seal; 84. Rotary seal for shaft. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] As shown in Figure 2 , 3 , a swing cylinder comprises: a cylinder body 1, a channel extending along the axial direction of the cylinder body 1 is arranged in the cylinder body 1; an output shaft body 2, at least a part of the output shaft body 2 extends into the channel of the cylinder body 1, and a piston channel 3 is formed between the cylinder body 1 and the output shaft body 2; an end cover 4, the end cover 4 is arranged at one end of the cylinder body 1, and is used for closing the end of the piston channel 3; a piston 5, the piston 5 is arranged in the piston channel 3, an outer helical tooth is arranged on the outer wall of the piston 5, and the outer helical tooth is engaged with an inner helical tooth on the inner wall of the cylinder body 1 to form a helical transmission pair 6, the piston 5 divides the piston channel 3 into a first chamber 31 and a second chamber 32, a first oil inlet hole 11 communicating with the first chamber 31 and a second oil inlet hole 12 communicating with the second chamber 32 are arranged on the cylinder body 1; a first locking nut 23 is further arranged, and the first locking nut 23 is fixedly arranged on the inner wall of the cylinder body 1.

[0022] Specifically, the cylinder body 1 is internally provided with an axially extending channel to provide installation space for other components, at least a part of the output shaft body 2 extends into the channel of the cylinder body 1, and an annular piston channel 3 is formed between the outer wall of the output shaft body 2 and the inner wall of the cylinder body 1; the end cover 4 is located at one end of the cylinder body 1 and closes the end of the piston channel 3; the piston 5 is assembled in the piston channel 3, the outer helical teeth of the outer wall of the piston 5 are engaged with the inner helical teeth of the inner wall of the cylinder body 1 to form a helical transmission pair 6, and at the same time, the piston 5 divides the piston channel 3 into independent first and second chambers 31 and 32; the cylinder body 1 is further provided with first and second oil supply holes 11 and 12, which are respectively communicated with the first and second chambers 31 and 32; the first locking nut 23 is located inside the cylinder body 1 and is fixedly arranged on the inner wall of the cylinder body 1, and is located at the power output end of the output shaft body 2. When hydraulic oil enters the first chamber 31 through the first oil supply hole 11, the hydraulic thrust pushes the piston 5 to move in the direction of the second chamber 32, and due to the engagement of the helical teeth of the piston 5 and the cylinder body 1, the piston 5 rotates while moving axially, thereby driving the output shaft body 2 to rotate synchronously; when hydraulic oil enters the second chamber 32 through the second oil supply hole 12, the piston 5 moves axially in the opposite direction and rotates in the opposite direction, thereby driving the output shaft body 2 to rotate in the opposite direction through the same transmission path, and finally realizing the clockwise-anticlockwise cyclic swinging of the output shaft body 2. In this application, the first locking nut 23 is fixedly connected with the cylinder body 1, and when the piston 5 moves in the direction of the second chamber 32, the hydraulic pressure acting on the output shaft body 2 is transmitted to the cylinder body 1 through the first locking nut 23, so that the hydraulic pressure pushing the piston 5 no longer directly acts on the output shaft body 2, thereby avoiding the transmission of the reaction force of the hydraulic pressure pushing the piston 5 to the thrust washer or the needle bearing, so that the thrust washer or the needle bearing can rotate and rub under the action of a large hydraulic pressure, and is quickly worn or damaged, causing the shaft to fail, thereby prolonging the service life of the thrust component.

[0023] As shown in Figure 2 , the inner wall of the piston 5 is provided with internal spline teeth, the output shaft body 2 and the internal spline teeth of the piston 5 form a spline engagement transmission pair 7, and the spline engagement transmission pair 7 is a helical tooth transmission or a straight tooth transmission.

[0024] Specifically, the inner wall of the piston 5 is provided with internal spline teeth, and the output shaft body 2 and the internal spline teeth form a spline engagement transmission pair 7, which can be a helical tooth transmission or a straight tooth transmission, and can be flexibly selected according to actual needs, taking into account the performance requirements in different scenarios.

[0025] As shown in Figure 2 , the spline engagement transmission pair 7 is a straight tooth spline engagement transmission pair. Specifically, the spline meshing transmission pair 7 is a straight-tooth spline meshing transmission pair. The straight-tooth spline transmission only transmits torque without generating axial force, so that the output shaft body 2 only bears torque when receiving the rotational motion transmitted by the piston 5, and the generation of axial force is completely avoided. According to the principle of action and reaction, the impact of axial force in the traditional structure is completely eliminated, and the problems of wear of thrust washer or needle bearing, output shaft stringing, oil cylinder jamming, and even failure caused by the axial force acting on the thrust component due to the helical tooth meshing of the piston and the output shaft in the traditional oil cylinder are solved, thereby significantly prolonging the service life and operation stability of the swing oil cylinder. As shown in Figure 2 , 3 , the output shaft body 2 includes an output shaft 21 and an inner shaft 22. The inner shaft 22 is provided with an outer straight-tooth spline and is meshed with an inner straight-tooth spline on the inner wall of the piston 5 to form a first straight-tooth spline meshing transmission pair 71. The inner shaft 22 is provided with an inner straight-tooth spline, and the output shaft 21 is provided with an outer straight-tooth spline. The outer straight-tooth spline on the output shaft 21 is meshed with the inner straight-tooth spline on the inner shaft 22 to form a second straight-tooth spline meshing transmission pair 72. The output shaft 21 is provided with an output shaft positioning step, and the inner shaft 22 is provided with an inner shaft positioning step. The output shaft 21 is in abutting engagement with the inner shaft 22. Specifically, the split design of the inner shaft 22 and the output shaft 21 realizes function separation and anti-interference optimization through two-stage straight-tooth spline pair series transmission and end face abutting positioning. The precise sealing cooperation of the inner shaft 22 and the cylinder body 1 can be individually optimized for high-pressure sealing, effectively isolating the interference of external eccentric load and bending moment on the output shaft 21 on the sealing system. The small gap (e.g., 0.1 mm) between the two spline meshing provides adaptive buffer space when the output shaft 21 is subjected to external force eccentricity, preventing damage to the sealing of the inner shaft 22 and the cylinder body 1 due to rigid interference. At the same time, the output shaft 21 can be flexibly disassembled or replaced as an independent module. The output shaft 21 can be a flange with screw holes or an adapter, which can be connected to various regular and irregular geometric bodies in one or more connection modes such as spline output, flat key output, and square key output, greatly improving the working condition adaptability, maintenance convenience, and functional expandability of the product. As shown in Figure 3 , the inner shaft 22 is provided with a locking positioning step 221, and the first locking nut 23 is located at the locking positioning step 221. The first locking nut 23 is located between the inner shaft 22 and the output shaft 21. The first locking nut 23 is made of wear-resistant ductile iron material and is lubricated with anti-wear grease.

[0026] Specifically, the first locking nut 23 is located at the locking positioning step 221 of the inner shaft 22 and between the inner shaft 22 and the output shaft 21, the locking positioning step 221 provides installation positioning reference for the inner shaft 22, and the hydraulic pressure borne by the inner shaft 22 and the output shaft 21 is transmitted to the cylinder body 1, the wear-resistant ductile iron material and the anti-wear grease lubrication are adopted, the compression resistance and wear resistance are improved, and the friction loss is reduced.

[0027] As shown in Figure 2 , 3 , a second locking nut 24 is further arranged on the output shaft body 2, the second locking nut 24 is located on the side close to the end cover 4, the second locking nut 24 is connected through the shaft head locking thread on the output shaft 21, is fixed after being tightened by a threaded pin, and rotates synchronously with the output shaft 21.

[0028] Specifically, the second locking nut 24 is connected through the shaft head locking thread, is fixed after being tightened by a threaded pin, and rotates synchronously with the output shaft 21, the hydraulic pressure borne by the output shaft body 2 is transmitted to the cylinder body 1 through cooperation with the end cover 4, and the hydraulic pressure is avoided from acting directly on the output shaft body 2; the double positioning structure formed by the first locking nut 23 and the second locking nut 24 reduces the eccentricity of the output shaft body 2 through positioning action, avoids the sealing element from being damaged due to eccentricity, further improves the sealing reliability of the swing oil cylinder, reduces the oil leakage failure, and guarantees the long-term stable operation of the swing oil cylinder.

[0029] As shown in Figure 3 , a first shaft load element 25 is sleeved on the inner shaft 22, the first shaft load element 25 is a thrust washer or a needle bearing, and the first shaft load element 25 is located between the bearing positioning step 222 of the inner shaft 22 and the positioning step of the cylinder body 1; the bearing positioning step 222 of the inner shaft 22 is an annular shaft shoulder, forms axial limiting for the first shaft load element 25; the first locking nut 23 is located on the outer side of the first shaft load element 25, forms locking positioning for the first shaft load element 25, and can adjust the gap therebetween. Specifically, the annular shaft shoulder of the inner shaft 22 and the positioning step of the cylinder body 1 jointly form axial limiting for the first shaft load element 25, ensure the position stability of the first shaft load element 25 when being stressed, and avoid axial movement; the first shaft load element 25 greatly reduces the friction force when the inner shaft 22 rotates through the rolling friction characteristic; the first locking nut 23 can not only form reliable locking positioning for the bearing, but also can flexibly adjust the gap, so that the first shaft load element 25 is always in the best working state; the overall structure transmits external force to the cylinder body 1 through the first shaft load element 25 and the first locking nut 23, avoids deformation of the inner shaft 22 directly stressed, and improves the stability of transmission and the service life of components. As shown in Figure 3As shown, the end cover 4 is provided with an external thread that engages with the internal thread of the cylinder body 1, thereby fixing the end cover 4 onto the cylinder body 1. The end cover 4 is provided with a bearing mounting position, and a second shaft load element 26 is provided in the bearing mounting position. The second shaft load element 26 is a thrust washer or a needle roller bearing. The second shaft load element 26 is located between the end cover 4 and the second locking nut 24. One end of the second shaft load element 26 contacts the end face of the bearing mounting position of the end cover 4, and the other end contacts the end face of the second locking nut 24. Specifically, the end cover 4 is securely connected to the cylinder body 1 via an external thread. A second shaft load element 26, positioned in its bearing mounting location, is located between the end cover 4 and the second locking nut 24, with both ends contacting the bearing mounting face of the end cover 4 and the end face of the second locking nut 24, respectively. The end cover 4 is fixedly mounted on the cylinder body 1, ensuring not only the sealing of the assembly between the end cover 4 and the cylinder body 1 to prevent hydraulic oil leakage, but also ensuring the stability of the mounting position of the second shaft load element 26. The second shaft load element 26 reduces the frictional resistance of the output shaft 21 during rotation through rolling friction. The end cover 4 is fixedly connected to the cylinder body 1. When the piston 5 moves towards the first chamber 31, the hydraulic pressure borne by the output shaft body 2 is transmitted to the cylinder body 1 through the end cover 4. This prevents the hydraulic pressure driving the piston 5 from directly acting on the output shaft body 2, thus avoiding the output shaft body 2 transmitting the reaction force of the hydraulic pressure driving the piston 5 to the thrust washer or needle roller bearing.

[0030] like Figure 3 As shown, the power output end of the output shaft 21 is provided with a first guide ring 27. The outer ring of the first guide ring 27 mates with the inner wall of the cylinder 1, and the inner ring of the first guide ring 27 mates with the outer wall of the output shaft 21. They are radially distributed between the output shaft 21 and the cylinder 1. The end cover 4 is provided with a guide ring mounting position. A second guide ring 28 is provided in the guide ring mounting position. The outer ring of the second guide ring 28 mates with the inner wall of the end cover 4, and the inner ring of the second guide ring 28 mates with the outer wall of the second locking nut 24. They are radially distributed between the second locking nut 24 and the end cover 4. Both the first guide ring 27 and the second guide ring 28 are made of iron-based oil-free lubricated bushings. Specifically, the first guide ring 27 is radially distributed between the output shaft 21 and the cylinder body 1, the outer ring is matched with the inner wall of the cylinder body 1, and the inner ring is matched with the outer wall of the output shaft 21, the second guide ring 28 is arranged in the guide ring mounting position of the end cover 4, the outer ring is matched with the inner wall of the end cover 4, and the inner ring is matched with the outer wall of the second locking nut 24, the mounting structure of the two breaks away from the limitation that the traditional guide ring needs to be installed in the internal groove, and the carrying capacity of the guide ring can be increased; at the same time, both of them adopt the iron-based oil-free lubrication shaft sleeve with large carrying capacity, further increasing the overall carrying capacity, effectively solving the problems that the traditional guide ring has low pressure capacity due to the limited area, wears fast under the eccentric load, causes the eccentricity of the output shaft 21, increases the sealing extrusion gap, causes the sealing damage and oil cylinder leakage failure; in addition, the external design of the guide ring avoids the disadvantages that the traditional internal guide ring pollutes the entire hydraulic system after wearing, and can also provide stable radial support for the output shaft 21 and the second locking nut 24, reducing the friction force during movement.

[0031] As shown in Figure 3 a plurality of sealing assemblies are further arranged, the first main seal 81 is arranged between the inner shaft 22 and the cylinder body 1, is installed in the sealing groove of the cylinder body 1, and is in close contact with the outer wall of the inner shaft 22; the shaft static seal 82 is arranged between the output shaft 21 and the inner shaft 22, is installed in the sealing groove of the inner shaft 22; the second main seal 83 is arranged between the end cover 4 and the cylinder body 1, is installed in the sealing groove of the end cover 4, the shaft rotary dynamic seal 84 is arranged between the end cover 4 and the output shaft 21, is installed in the sealing groove of the end cover 4, and is in close contact with the outer wall of the output shaft 21. Specifically, the first main seal 81 is a rotary dynamic seal, and is installed in a groove of the cylinder body 1. Due to the split design of the inner shaft 22 and the output shaft 21, the inner shaft 22 can focus on the sealing function, and the size precision of the matching surface can be independently optimized, so that the extrusion gap of the first main seal 81 can be significantly reduced (much lower than 0.2-0.3mm in traditional design), and the small design gap avoids the shear damage caused by the extrusion of the seal lip into the gap under high pressure oil, greatly improving the service life and reliability of the first main seal 81 under high pressure and partial load conditions, and solving the pain point of easy extrusion failure of the traditional oil cylinder main seal. The shaft static seal 82 is arranged between the output shaft 21 and the inner shaft 22, and the output shaft 21 and the inner shaft 22 are matched by end face stop. Since the two are connected by spline and rotate synchronously without relative motion, friction and wear are avoided, and the service life of the seal is improved. The end cover 4 is fixedly installed on the cylinder body 1 and does not rotate with the output shaft 21, so that the end cover 4 and the cylinder body 1 form a static seal, which significantly prolongs the service life of the seal at this part; the shaft rotary dynamic seal 84 is arranged between the end cover 4 and the output shaft 21. Since the output shaft 21 is fixedly connected with the second locking nut 24 and is positioned by a threaded pin, and the second guide ring 28 is arranged radially between the second locking nut 24 and the end cover 4, the coaxiality of the output shaft 21 and the end cover 4 can be effectively guaranteed, so that the extrusion gap of the shaft rotary dynamic seal 84 can be appropriately reduced, thereby greatly improving the service life of the dynamic seal. As shown in Figure 3 , the second straight tooth spline meshing transmission pair 72 is a small modulus and large tooth number structure, and the rotation starting point of the output shaft 21 can be adjusted by changing the meshing tooth position of the output shaft 21 and the inner shaft 22. Specifically, the modulus value is equal to the ratio (m=d / z) of the diameter (d) of the reference circle to the number (z) of teeth, and the smaller the modulus, the more teeth can be arranged under the same diameter. The straight tooth spline meshing transmission pair adopts a small modulus and large tooth number structure, which can realize finer indexing under the same diameter, and the angle deviation can be controlled within 4 degrees, meeting the error standard of 180-degree rotation ± 2 degrees of the product, effectively avoiding the problem of angle deviation exceeding the standard caused by tooth error of large modulus gear, and significantly improving the indexing accuracy; by adjusting the rotation starting point of the output shaft 21 through the method of changing the meshing tooth position, the assembly flexibility and efficiency are greatly improved, and the accuracy and assembly convenience are considered. As shown in Figure 3 , 5As shown, the inner helical teeth of the inner wall of the cylinder body 1 can be integrally formed with the cylinder body 1, or can be fixedly installed on the inner wall of the passage of the cylinder body 1 by a separately processed inner tooth fixing piece. The piston 5 and the cylinder body 1 are provided with a first piston sealing piece for sealing hydraulic oil, and the piston 5 and the output shaft body 2 are provided with a second piston sealing piece for sealing hydraulic oil. The first piston sealing piece and the second piston sealing piece can be located on the same side of the piston 5 or can be located on both sides of the piston 5.

[0032] Specifically, the integrally formed structure can ensure the integrity of the inner helical teeth and the cylinder body 1, and guarantee the structural strength. When the separately processed inner tooth fixing piece is used, if the piston 5 with different parameters needs to be adapted, only the inner tooth fixing piece needs to be replaced, which can flexibly meet the demand of the helical teeth parameters under different working conditions. The first piston sealing piece and the second piston sealing piece can be located on the same side of the piston 5 or can be located on both sides of the piston 5. The two layout modes can be flexibly selected according to the overall structural size, internal chamber space and assembly process demand of the swing oil cylinder.

[0033] As shown in Figure 4 , 4 , the output shaft 21 can be designed as an integrated output shaft, or can be designed as a split output shaft. The split output shaft is disconnected from the second straight tooth spline meshing transmission pair 72 away from the power output end side of the output shaft 21, and is divided into a sealing section extending into the piston passage 3 and an output section for power output. The sealing section cooperates with the piston 5 to realize sealing. The output section of the output shaft 21 can be a flange with a screw hole or can be an adapter to adapt various regular and irregular geometric connection modes, such as one or more connection modes of spline output, flat key output, square key output. Specifically, the integrated design guarantees the overall rigidity and transmission stability of the output shaft 21, which is suitable for scenes with high requirements on structural strength. As shown in ​ , in the split design of the output shaft 21, the sealing section only cooperates with the piston 5 to realize sealing and does not bear external force and bending moment, which can reduce the influence of external force on the sealing performance, prolong the service life of the sealing piece, and the output section can focus on power output, so that the structure reliability is improved. At the same time, the output section of the output shaft 21 can be a flange with a screw hole or can be an adapter to adapt various regular and irregular geometric connection modes, such as spline output, flat key output, square key output, etc., which can flexibly adapt to the installation requirements of different equipment, meet various working conditions without changing the internal core components of the oil cylinder, reduce the equipment adaptation cost, and enhance the universality of the product.

[0034] The application is a swing oil cylinder. When hydraulic oil enters the second chamber 32 through the second oil inlet hole 12, the piston 5 moves reversely in the axial direction and rotates reversely, drives the output shaft body 2 to rotate reversely through the same transmission path, and finally realizes the clockwise-anticlockwise cyclic swing of the output shaft body 2. In the application, the first locking nut 23 is fixedly connected with the cylinder body 1. When the piston 5 moves to the second chamber 32, the hydraulic pressure borne by the output shaft body 2 is transmitted to the cylinder body 1 through the first locking nut 23. The end cover 4 is fixedly connected with the cylinder body 1. When the piston 5 moves to the first chamber 31, the hydraulic pressure borne by the output shaft body 2 is transmitted to the cylinder body 1 through the end cover 4. The two work together to make the hydraulic pressure for reciprocating the piston 5 no longer directly act on the output shaft body 2, avoid the reaction force of the hydraulic pressure for reciprocating the piston 5 being transmitted to the thrust washer or the needle bearing by the output shaft body 2, make the thrust washer or the needle bearing rotate and rub under the condition of bearing huge hydraulic pressure, and be quickly worn or damaged, cause the shaft jamming failure, and prolong the service life of the thrust part. The first locking nut 23 and the end face of the output shaft body 2 are positioned and stopped by the first shaft load element 25 and the positioning step of the cylinder body 1, and the two work together to greatly improve the ability of the overall structure to resist the eccentric load bending moment, avoid the sealing element being extruded and damaged due to the increased extrusion gap caused by the eccentric load, further improve the sealing reliability of the swing oil cylinder, reduce the oil leakage failure, and ensure the long-term stable operation of the swing oil cylinder. The swing oil cylinder of the application is especially suitable for the high-altitude working platform field and the excavator accessory rotating field, the core advantage lies in the double optimization of the structure and stress design, the first locking nut 23 is fixedly connected with the cylinder body 1, the end cover 4 is fixedly connected with the cylinder body 1, the two work together to transmit the hydraulic pressure for reciprocating the piston 5 and the reaction force to the cylinder body 1, and avoid the impact of the axial force on the thrust part; in addition, the external setting of the guide ring and the two work together to greatly improve the ability of the overall structure to resist the eccentric load bending moment, and provide protection for the stable operation of the oil cylinder under the eccentric load working condition. On this basis, the straight tooth spline meshing transmission pair formed by the inner straight tooth spline of the piston 5 and the output shaft body 2 only transmits the torque without axial force, so that the output shaft body 2 only bears the static load of the platform, the straight tooth design eliminates the axial force, the shaft load element only bears the static load of the platform without hydraulic impact force when the oil is filled and the load is eccentric, the wear risk is greatly reduced, the stable operation is ensured, the service life is prolonged, and the high requirement of the field on the equipment reliability is met.

[0035] According to the swing oil cylinder as an example, taking the swing oil cylinder with a working pressure of 21 MPa, a starting pressure of 3.5 MPa, and an output torque of 1600 N·m as an example, when the first oil inlet hole 11 inputs high-pressure oil P1=21 MPa, the second oil inlet hole 12 has a pressure P2=3.5 MPa, and the piston has a force area of 7398 mm2, the axial working force of the piston is calculated to be 129475 N. That is, to achieve an output torque of 1600 N·m, the force acting on the piston 5 needs to reach 129475 N (about 12.9×10³ kgf) to push the piston to move axially. According to the structural design of the present application, according to the principle of action and reaction, this force will eventually act on the first locking nut 23; conversely, when the second oil inlet hole 12 inputs 21 MPa high-pressure oil, this force will eventually act on the end cover 4, unlike the traditional swing oil cylinder, the force will act on the thrust washer or the needle bearing, causing the thrust washer or the needle bearing to rotate while bearing a large pressure, and then causing wear or rupture failure.

[0036] Although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

[0037] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

Claims

1. A swing cylinder, comprising: a cylinder body (1) having a channel extending axially therein; an output shaft body (2) extending at least partially into the channel of the cylinder body (1) to form a piston channel (3) with the cylinder body (1); an end cover (4) located at one end of the cylinder body (1) to close an end of the piston channel (3); a piston (5) located in the piston channel (3), the piston (5) having external helical teeth on an outer wall thereof to engage with internal helical teeth of an inner wall of the cylinder body to form a helical transmission pair (6), the piston (5) dividing the piston channel (3) into a first chamber (31) and a second chamber (32); the cylinder body (1) having a first oil delivery hole (11) in communication with the first chamber (31) and a second oil delivery hole (12) in communication with the second chamber (32); characterized in that: a first locking nut (23) is further provided and fixedly arranged on the inner wall of the cylinder body (1) with the end cover (4).

2. A swing cylinder according to claim 1, characterized in that the inner wall of the piston (5) is provided with internal spline teeth, the output shaft body (2) and the internal spline teeth of the piston (5) form a spline engagement transmission pair (7), and the spline engagement transmission pair (7) is a helical tooth transmission or a straight tooth transmission.

3. A swing cylinder according to claim 2, characterized in that the spline engagement transmission pair (7) is a straight tooth spline engagement transmission pair.

4. A swing cylinder as claimed in claim 3, characterized in that the output shaft body (2) comprises an output shaft (21) and an inner shaft (22), the inner shaft (22) is provided with external straight tooth splines, the internal straight tooth splines of the inner wall of the piston (5) are engaged with the external straight tooth splines to form a first straight tooth spline engagement transmission pair (71); the inner shaft (22) is provided with internal straight tooth splines, the output shaft (21) is provided with external straight tooth splines, the external straight tooth splines on the output shaft (21) are engaged with the internal straight tooth splines on the inner shaft (22) to form a second straight tooth spline engagement transmission pair (72), the output shaft (21) is provided with an output shaft positioning step, the inner shaft (22) is provided with an inner shaft positioning step, and the output shaft (21) is in abutting engagement with the inner shaft (22).

5. A swing cylinder as claimed in claim 4, characterized in that the inner shaft (22) is provided with a locking positioning step (221), the first locking nut (23) is located at the locking positioning step (221), the first locking nut (23) is located between the inner shaft (22) and the output shaft (21), the first locking nut (23) is made of wear-resistant ductile cast iron material and is lubricated with anti-wear grease.

6. A swing cylinder as claimed in claim 5, characterized in that a second locking nut (24) is further provided, the second locking nut (24) is arranged on the output shaft body (2), the second locking nut (24) is located on a side close to the end cover (4), the second locking nut (24) is connected through a shaft head locking thread on the output shaft (21), is fixed with a threaded pin after being tightened, and rotates synchronously with the output shaft (21).

7. The swing cylinder of claim 4 wherein, The inner shaft (22) is sleeved with a first shaft load element (25), which is a thrust washer or a needle bearing, and is located between a bearing positioning step (222) of the inner shaft (22) and a positioning step of the cylinder body (1); the bearing positioning step (222) is an annular shaft shoulder, which axially limits the first shaft load element (25); the first locking nut (23) is located outside the first shaft load element (25) and forms locking positioning and clearance adjustment of the first shaft load element (25).

8. The swing cylinder of claim 6 wherein, The end cover (4) is provided with external threads matched with internal threads of the cylinder body (1) to fixedly install the end cover (4) on the cylinder body (1), and is provided with a bearing mounting position, in which a second shaft load element (26) is arranged, which is a thrust washer or a needle bearing and is located between the end cover (4) and the second locking nut (24); one side of the second shaft load element (26) is in contact with an end face of the bearing mounting position of the end cover (4), and the other side is in contact with an end face of the second locking nut (24).

9. The swing cylinder of claim 6 wherein, The power output end of the output shaft (21) is provided with a first guide ring (27), an outer ring of the first guide ring (27) is matched with an inner wall of the cylinder body (1), an inner ring of the first guide ring (27) is matched with an outer wall of the output shaft (21), and the first guide ring (27) is radially distributed between the output shaft (21) and the cylinder body (1); the end cover (4) is provided with a guide ring mounting position, a second guide ring (28) is arranged in the guide ring mounting position, an outer ring of the second guide ring (28) is matched with an inner wall of the end cover (4), an inner ring of the second guide ring (28) is matched with an outer wall of the second locking nut (24), and the second guide ring (28) is radially distributed between the second locking nut (24) and the end cover (4); the first guide ring (27) and the second guide ring (28) are iron-based oil-free lubrication bushes.

10. The swing cylinder of claim 4 wherein, A plurality of sealing assemblies are further arranged, a first main seal (81) is arranged between the inner shaft (22) and the cylinder body (1) and is installed in a sealing groove of the cylinder body (1) and is in close contact with an outer wall of the inner shaft (22); a shaft static seal (82) is arranged between the output shaft (21) and the inner shaft (22) and is installed in a sealing groove of the inner shaft (22); a second main seal (83) is arranged between the end cover (4) and the cylinder body (1) and is installed in a sealing groove of the end cover (4); a shaft rotary dynamic seal (84) is arranged between the end cover (4) and the output shaft (21) and is installed in a sealing groove of the end cover (4) and is in close contact with an outer wall of the output shaft (21).

11. The swing cylinder of claim 4 wherein, The second straight tooth spline meshing transmission pair (72) is a small modulus and multi-tooth structure, and the rotation starting point of the output shaft (21) can be adjusted by changing the meshing tooth position of the output shaft (21) and the inner shaft (22).

12. The swing cylinder of claim 1 wherein, The inner spiral tooth of the inner wall of the cylinder body (1) can be integrally formed with the cylinder body (1), or can be fixedly installed on the inner wall of the passage of the cylinder body (1) by a separately processed inner tooth fixing piece. A first piston sealing piece for sealing hydraulic oil is arranged between the piston (5) and the cylinder body (1), and a second piston sealing piece for sealing hydraulic oil is arranged between the piston (5) and the output shaft body (2). The first piston sealing piece and the second piston sealing piece can be located on the same side of the piston (5), or can be located on both sides of the piston (5) respectively.

13. The swing cylinder of claim 4 wherein, The output shaft (21) can be designed as an integrated output shaft, or can be designed as a split type output shaft. The split type output shaft is disconnected from the side of the power output end of the output shaft (21) away from the second straight tooth spline meshing, and is divided into a sealing section extending into the piston passage and an output section for power output. The sealing section cooperates with the piston (5) to realize sealing. The output section of the output shaft (21) can be a flange with a threaded hole, or can be an adapter suitable for connecting various regular and irregular geometric bodies, such as one or more connection modes of spline output, flat key output, square key output.

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