Compact swing hydraulic cylinder for mechanical arm

Abstract

The utility model provides a compact type swing hydraulic cylinder for a mechanical arm, which is provided with an outer shell, a main shaft is arranged in the outer shell, and a main shaft left side supporting sleeve and a main shaft right side supporting sleeve are respectively arranged between shaft sections on two sides of the inner circumference of the outer shell on the main shaft and the inner circumference of the outer shell. A spindle middle supporting sleeve is arranged between the spindle left supporting sleeve and the spindle right supporting sleeve and located in the outer shell, the outer circumference of the spindle middle supporting sleeve is fixedly connected with the inner circumference of the outer shell, and the inner circumference of the spindle middle supporting sleeve is rotationally connected with the outer circumference of the spindle in a sealed mode. The spindle left side supporting sleeve and the spindle middle supporting sleeve axially limit and support the spindle. According to the swing hydraulic cylinder, the groove is formed in the outer circumference of the main shaft, machining is convenient and fast, machining precision is high, the sealing ring is placed in the groove in the outer circumference of the main shaft, and the sealing performance between the outer shell and the main shaft supporting sleeve and the sealing performance between the main shaft supporting sleeve and the main shaft are effectively improved. The utility model can be widely applied to compact swing hydraulic cylinders.

Description

Technical Field

[0001] The utility model relates to a swing hydraulic cylinder, in particular to a compact swing hydraulic cylinder for a mechanical arm. Background Art

[0002] The swing hydraulic cylinder is a special hydraulic cylinder mainly used to provide high-torque rotational motion in a limited space. It has the advantages of compact structure, safety and reliability, small footprint, easy design, large output torque and swing angle, etc.

[0003] Since hydraulic oil is injected into the swing hydraulic cylinder, there are high standard requirements for the sealing strength inside the cylinder. Most of the existing hydraulic cylinders ensure the sealing between the outer shell and the spindle support sleeve, as well as between the spindle support sleeve and the spindle by opening grooves on the inner wall of the outer shell and the inner wall of the spindle support sleeve, and placing sealing rings in the grooves. However, for smaller hydraulic cylinders, such as small hydraulic cylinders used in robotic arms, it is difficult to process grooves on the inner wall of the outer shell and the inner wall of the spindle support sleeve, and the accuracy of the groove processing cannot be guaranteed. Ultimately, the sealing between the outer shell and the spindle support sleeve, as well as between the spindle support sleeve and the spindle cannot be guaranteed. Utility Model Content

[0004] In response to the above technical problems, the utility model provides a compact swing hydraulic cylinder for a robot arm. The compact swing hydraulic cylinder for the robot arm has multiple grooves on the outer circumference of the main shaft, which is convenient and fast to process and has high processing precision, thereby avoiding the problem of difficulty in processing grooves on the circumference of the outer shell due to the small overall volume of the swing cylinder.

[0005] In addition, by placing a dustproof sealing ring, an oil sealing ring and a wear-resistant support pad in the groove respectively, the dustproof sealing ring and the oil sealing ring can effectively improve the sealing between the outer shell and the main shaft support sleeve, as well as between the main shaft support sleeve and the main shaft. The wear-resistant support pad can increase the wear resistance of the support between the main shaft and the main shaft support sleeve when the main shaft rotates, and at the same time ensure the smoothness of the rotational friction between the main shaft and the main shaft support sleeve, reduce the resistance when the main shaft rotates, and reduce the operating noise, thereby achieving long-term stable operation of the swing cylinder and extending its service life.

[0006] To this end, the technical solution of the utility model is a compact swing hydraulic cylinder for a robotic arm, comprising an outer shell, a left oil hole and a right oil hole provided on the outer shell, and a left fixed support sleeve and a right fixed support sleeve fixedly provided on both sides of the outer circumference of the outer shell;

[0007] A main shaft is provided inside the outer shell, and shaft sections on both sides of the main shaft are located outside the outer shell. A main shaft left support sleeve and a main shaft right support sleeve are respectively provided between the shaft sections located on both sides of the inner circumference of the outer shell and the inner circumference of the outer shell. The outer circumferences of the main shaft left support sleeve and the main shaft right support sleeve are respectively sealed and fixedly connected to the inner circumference of the outer shell, and the inner circumferences of the main shaft left support sleeve and the main shaft right support sleeve are respectively rotatably sealed and connected to the outer circumference of the main shaft;

[0008] A main shaft intermediate support sleeve is provided between the main shaft left support sleeve and the main shaft right support sleeve and located inside the outer shell. The outer circumference of the main shaft intermediate support sleeve is fixedly connected to the inner circumference of the outer shell, and the inner circumference of the main shaft intermediate support sleeve is rotatably sealed with the outer circumference of the main shaft.

[0009] The left side support sleeve of the main shaft and the middle support sleeve of the main shaft provide axial limit support for the main shaft;

[0010] A rotary piston is provided between the outer circumference of the main shaft and the inner circumference of the outer shell. The outer circumference and inner circumference of one side of the rotary piston are respectively engaged with the inner circumference of the outer shell and the outer circumference of the main shaft. The outer circumference and inner circumference of the other side of the rotary piston are respectively rotated and sealed with the inner circumference of the outer shell and the outer circumference of the main shaft. The rotary piston can realize axial rotation and translation between the main shaft and the outer shell. The rotary piston can drive the main shaft to rotate while axially rotating and translating.

[0011] An oil chamber is formed between the middle support sleeve of the main shaft, the main shaft and the support sleeve on the right side of the main shaft. The two sides of the oil chamber are respectively connected to the left oil hole and the right oil hole.

[0012] Preferably, the main shaft is provided with a first main shaft section, a second main shaft section, a third main shaft section, a fourth main shaft section, a fifth main shaft section, and a sixth main shaft section in sequence from left to right;

[0013] The first and sixth main shaft segments are located outside the outer shell, the second and fifth main shaft segments are located on both sides of the inner circumference of the outer shell, and the third and fourth main shaft segments are located in the middle of the inner circumference of the outer shell.

[0014] The left side support sleeve of the main shaft is located between the second shaft section of the main shaft and the leftmost inner circumference of the outer shell, and the right side support sleeve of the main shaft is located between the fifth shaft section of the main shaft and the rightmost inner circumference of the outer shell;

[0015] The outer circumferences of the second and fifth spindle sections are each provided with a plurality of grooves, each of which is provided with a wear-resistant support pad, an oil sealing ring, and a dust-proof sealing ring. The wear-resistant support pad, the oil sealing ring, and the dust-proof sealing ring are arranged in sequence from the inside to the outside on the outer circumferences of the second and fifth spindle sections;

[0016] The outer circumferences of the left and right spindle support sleeves are each provided with a plurality of grooves, in which oil sealing rings and dustproof sealing rings are respectively provided. The oil sealing rings and dustproof sealing rings are arranged in sequence from the inside to the outside on the outer circumferences of the left and right spindle support sleeves;

[0017] The third shaft section of the main shaft is located on the inner side of the support sleeve on the left side of the main shaft. The third shaft section of the main shaft extends outward to form a stepped shaft structure. The first shaft shoulder and the second shaft shoulder are respectively provided on both sides of the axial direction of the third shaft section of the stepped shaft structure.

[0018] A wear-resistant support pad is provided between the position of the first shaft shoulder of the third shaft section of the main shaft and the support sleeve on the left side of the main shaft.

[0019] Preferably, the spindle intermediate support sleeve is located between the second shaft shoulder position on the outer circumference of the third shaft segment of the spindle and the inner circumference of the outer shell, the outer circumference of the spindle intermediate support sleeve is fixedly connected to the inner circumference of the outer shell, the inner circumference of the spindle intermediate support sleeve is provided with a groove, an oil sealing ring is provided in the groove, and the inner circumference of the spindle intermediate support sleeve and the outer circumference of the third shaft segment of the spindle are rotationally sealed by the oil sealing ring;

[0020] A wear-resistant support pad is provided between the intermediate support sleeve of the main shaft and the position of the third shaft section of the main shaft located at the second shaft shoulder;

[0021] The left side support sleeve of the main shaft and the middle support sleeve of the main shaft respectively realize axial limited rotation support for the third shaft section of the main shaft through wear-resistant support pads located at the first shaft shoulder and the second shaft shoulder.

[0022] Preferably, the rotary piston comprises a rotary piston rotation support section and a rotary piston rotation sealing section, wherein the rotary piston rotation support section is located on the left side of the rotary piston, and the rotary piston rotation sealing section is located on the right side of the rotary piston;

[0023] The outer circumference of the rotary piston rotation support section is threadedly engaged with the inner circumference of the outer shell, and the inner circumference of the rotary piston rotation support section is threadedly engaged with the outer circumference of the fourth shaft section of the main shaft;

[0024] The outer circumference of the rotary sealing section of the rotary piston is provided with a groove, and an oil sealing ring is provided in the groove. The outer circumference of the rotary sealing section of the rotary piston and the inner circumference of the outer shell are rotary sealed by the oil sealing ring;

[0025] The inner circumference of the rotary sealing section of the rotary piston is provided with a groove, and an oil sealing ring is provided in the groove. The inner circumference of the rotary sealing section of the rotary piston and the outer circumference of the fourth shaft section of the main shaft are rotary sealed by the oil sealing ring;

[0026] The rotary sealing section of the rotary piston divides the oil chamber into a left oil chamber and a right oil chamber. The left oil chamber is communicated with the left oil hole, and the right oil chamber is communicated with the right oil hole.

[0027] The beneficial effects of the utility model are:

[0028] 1. This oscillating cylinder has grooves formed on the outer circumference of the spindle, making machining quick and easy, with high precision. Furthermore, a wear-resistant support pad, an oil seal, and a dust-proof seal are placed in the grooves on the outer circumference of the spindle. The wear-resistant support pad prevents direct friction between the spindle and the spindle support sleeve, which would otherwise cause increased noise in the oscillating cylinder. It also reduces frictional resistance between the spindle and the spindle support sleeve, thereby increasing the stability of the spindle during rotation.

[0029] By setting up an oil sealing ring, the hydraulic oil in the oil chamber can be prevented from leaking outward through the corresponding gap, effectively improving the sealing between the outer shell and the main shaft support sleeve, and between the main shaft support sleeve and the main shaft;

[0030] By providing a dustproof sealing ring on the outermost side, dust and foreign matter in the external environment can be prevented from entering the cylinder and causing damage to related components.

[0031] 2. Since the left side support sleeve and the middle support sleeve of the main shaft respectively realize axial limited rotation support for the third shaft section of the main shaft through the wear-resistant support pads located at the first shoulder and the second shoulder positions, the axial positioning support of the main shaft is realized. When the main shaft rotates, the support of the wear-resistant support pads on both sides can avoid axial shaking of the main shaft during rotation, thereby ensuring the stability of the overall operation of the swing cylinder and the accuracy of the spindle during swing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a three-dimensional diagram of the utility model;

[0033] Figure 2 It is another three-dimensional diagram of the utility model;

[0034] Figure 3 This is the main view of the utility model;

[0035] Figure 4 This utility model Figure 3 Middle AA section view;

[0036] Figure 5 This is a schematic diagram of the main shaft structure of the utility model;

[0037] Figure 6 This utility model Figure 4 Enlarged view of point B in the middle.

[0038] Explanation of symbols in the figure:

[0039] 1. Outer shell; 2. Left oil hole; 3. Right oil hole; 4. Left fixed support sleeve; 5. Right fixed support sleeve; 6. Spindle left support sleeve; 7. Spindle right support sleeve; 8. Spindle; 801. Spindle first shaft section; 802. Spindle second shaft section; 803. Spindle third shaft section; 80301. First shaft shoulder; 80302. Second shaft shoulder; 804. Spindle fourth shaft section; 805. Spindle fifth shaft section; 806. Spindle sixth shaft section; 9. Spindle intermediate support sleeve; 10. Rotary piston; 1001. Rotary piston rotary support section; 1002. Rotary piston rotary sealing section; 11. Dustproof sealing ring; 12. Oil sealing ring; 13. Wear-resistant support pad; 14. Oil chamber; 1401. Left oil chamber; 1402. Right oil chamber. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the embodiments.

[0041] pass Figures 1-6 It can be seen that the compact swing hydraulic cylinder for the robotic arm is provided with an outer shell 1, on which a left oil hole 2 and a right oil hole 3 are provided. A left fixed support sleeve 4 and a right fixed support sleeve 5 are fixed on both sides of the outer circumference of the outer shell 1. The left fixed support sleeve 4 and the right fixed support sleeve 5 can be used as a normal connection operation with the robotic arm on the one hand, and on the other hand, the overall torsional strength of the outer shell 1 can be increased and the rigidity of the outer shell 1 can be improved, thereby ensuring the stability of the overall swing operation of the swing cylinder.

[0042] A main shaft 8 is provided inside the outer shell 1, and the shaft sections on both sides of the main shaft 8 are located outside the outer shell 1 for normal installation operations. A main shaft left support sleeve 6 and a main shaft right support sleeve 7 are respectively provided between the shaft sections on both sides of the inner circumference of the outer shell 1 and the inner circumference of the outer shell 1. The outer circumferences of the main shaft left support sleeve 6 and the main shaft right support sleeve 7 are respectively sealed and fixedly connected to the inner circumference of the outer shell 1, and the inner circumferences of the main shaft left support sleeve 6 and the main shaft right support sleeve 7 are respectively rotationally sealed and connected to the outer circumference of the main shaft 8. On the one hand, a static oil seal is realized between the left and right side support sleeves of the main shaft and the outer shell 1. On the other hand, the sealing between the left and right side support sleeves of the main shaft and the main shaft 8 is ensured when the main shaft 8 rotates, so as to prevent the oil in the oil chamber from leaking out.

[0043] A main shaft intermediate support sleeve 9 is provided inside the outer shell 1 between the main shaft left support sleeve 6 and the main shaft right support sleeve 7. The outer circumference of the main shaft intermediate support sleeve 9 is fixedly connected to the inner circumference of the outer shell 1, and the inner circumference of the main shaft intermediate support sleeve 9 is rotationally sealed with the outer circumference of the main shaft 8 to prevent the oil in the oil chamber from leaking outward along the gap between the main shaft intermediate support sleeve 9 and the main shaft 8.

[0044] The left side support sleeve 6 of the main shaft and the middle support sleeve 9 of the main shaft provide axial limit support for the main shaft 8, ensuring that the main shaft 8 can rotate normally in a fixed position, avoiding axial shaking when the main shaft 8 rotates, and ensuring the stability of the overall operation of the swing cylinder and the accuracy of the main shaft 8 when it swings.

[0045] A rotary piston 10 is provided between the outer circumference of the main shaft 8 and the inner circumference of the outer shell 1. The outer circumference and inner circumference of one side of the rotary piston 10 are respectively engaged with the inner circumference of the outer shell 1 and the outer circumference of the main shaft 8, and the outer circumference and inner circumference of the other side of the rotary piston 10 are respectively rotationally sealed with the inner circumference of the outer shell 1 and the outer circumference of the main shaft 8. The rotary piston 10 can realize axial rotation and translation between the main shaft 8 and the outer shell 1. While the rotary piston 10 rotates and translates axially, it can drive the main shaft 8 to rotate, thereby completing the swinging operation.

[0046] An oil chamber 14 is formed between the spindle middle support sleeve 9, the spindle 8, and the spindle right side support sleeve 7. Both sides of the oil chamber 14 are connected to the left oil hole 2 and the right oil hole 3 respectively.

[0047] The main shaft 8 is provided with a first main shaft section 801, a second main shaft section 802, a third main shaft section 803, a fourth main shaft section 804, a fifth main shaft section 805, and a sixth main shaft section 806 from left to right.

[0048] The first spindle section 801 and the sixth spindle section 806 are respectively located on the outside of the outer shell 1 for normal installation operations. The second spindle section 802 and the fifth spindle section 805 are respectively located on both sides of the inner circumference of the outer shell 1. The third spindle section 803 and the fourth spindle section 804 are respectively located in the middle of the inner circumference of the outer shell 1.

[0049] The left side support sleeve 6 of the main shaft is located between the second shaft section 802 of the main shaft and the leftmost inner circumference of the outer shell 1 , and the right side support sleeve 7 of the main shaft is located between the fifth shaft section 805 of the main shaft and the rightmost inner circumference of the outer shell 1 .

[0050] The outer circumferences of the second spindle section 802 and the fifth spindle section 805 are provided with multiple grooves, and the multiple grooves are respectively provided with wear-resistant support pads 13, oil sealing rings 12, and dust-proof sealing rings 11. The wear-resistant support pads 13, oil sealing rings 12, and dust-proof sealing rings 11 are arranged in sequence from the inside to the outside on the outer circumferences of the second spindle section 802 and the fifth spindle section 805.

[0051] Among them, the wear-resistant support pad 13 is made of materials with high wear resistance, high support force and high guiding stability such as PTFE+copper powder, phenolic cloth, cypress, nylon, etc., which can avoid direct friction between the main shaft 8 and the outer shell 1, causing the swing cylinder noise to increase, and reduce the friction resistance between the main shaft 8 and the outer shell 1, thereby increasing the stability of the main shaft 8 during rotation.

[0052] By providing the oil sealing ring 12 , it is possible to prevent the hydraulic oil in the oil chamber 14 from leaking outward through the corresponding gap.

[0053] By providing a dustproof sealing ring 11 on the outermost side, dust and foreign matter in the external environment can be prevented from entering the cylinder and causing damage to related components.

[0054] The outer circumferences of the left side support sleeve 6 and the right side support sleeve 7 of the main shaft are provided with multiple grooves, and the multiple grooves are respectively provided with oil sealing rings 12 and dustproof sealing rings 11. The oil sealing rings 12 and dustproof sealing rings 11 are arranged in sequence from the inside to the outside on the outer circumferences of the left side support sleeve 6 and the right side support sleeve 7 of the main shaft, thereby realizing static sealing and support between the left side support sleeve 6 and the right side support sleeve 7 of the main shaft and the outer shell 1 respectively.

[0055] The third shaft section 803 of the main shaft is located on the inner side of the left support sleeve 6 of the main shaft. The third shaft section 803 of the main shaft extends outward to form a stepped shaft structure. The first shaft shoulder 80301 and the second shaft shoulder 80302 are respectively provided on both axial sides of the third shaft section 803 of the stepped shaft structure.

[0056] A wear-resistant support pad 13 is provided between the first shaft shoulder 80301 on the third shaft section 803 of the main shaft and the left side support sleeve 6 of the main shaft.

[0057] The main shaft intermediate support sleeve 9 is located between the second shoulder 80302 on the outer circumference of the main shaft third shaft section 803 and the inner circumference of the outer shell 1. The outer circumference of the main shaft intermediate support sleeve 9 is fixedly connected to the inner circumference of the outer shell 1. The inner circumference of the main shaft intermediate support sleeve 9 is provided with a groove, and an oil sealing ring 12 is provided in the groove. The inner circumference of the main shaft intermediate support sleeve 9 and the outer circumference of the main shaft third shaft section 803 are rotated and sealed by the oil sealing ring 12, which can prevent the hydraulic oil in the oil chamber from leaking outward along the gap between the main shaft intermediate support sleeve 9 and the main shaft third shaft section 803.

[0058] A wear-resistant support pad 13 is provided between the intermediate support sleeve 9 of the main shaft and the position of the third shaft section 803 of the main shaft located at the second shaft shoulder 80302.

[0059] The left side support sleeve 6 of the main shaft and the middle support sleeve 9 of the main shaft respectively realize axial limited rotation support for the third shaft section 803 of the main shaft through the wear-resistant support pads 13 located at the first shoulder 80301 and the second shoulder 80302, and realize axial positioning support for the main shaft 8. When the main shaft 8 rotates, under the support of the wear-resistant support pads 13 on both sides, axial shaking of the main shaft 8 can be avoided during rotation, thereby ensuring the stability of the overall operation of the swing cylinder and the accuracy of the swing of the main shaft 8.

[0060] The rotary piston 10 includes a rotary piston rotation support section 1001 and a rotary piston rotation sealing section 1002 . The rotary piston rotation support section 1001 is located on the left side of the rotary piston 10 , and the rotary piston rotation sealing section 1002 is located on the right side of the rotary piston 10 .

[0061] The outer circumference of the rotary piston rotation support section 1001 is threadedly engaged with the inner circumference of the outer shell 1 , and the inner circumference of the rotary piston rotation support section 1001 is threadedly engaged with the outer circumference of the fourth shaft section 804 of the main shaft.

[0062] A groove is provided on the outer circumference of the rotary piston rotary sealing section 1002 , and an oil sealing ring 12 is provided in the groove. The outer circumference of the rotary piston rotary sealing section 1002 and the inner circumference of the outer shell 1 are rotary sealed by the oil sealing ring 12 .

[0063] The inner circumference of the rotary piston rotary seal section 1002 is provided with a groove, and an oil sealing ring 12 is provided in the groove. The inner circumference of the rotary piston rotary seal section 1002 and the outer circumference of the fourth shaft section 804 of the main shaft are rotary sealed by the oil sealing ring 12.

[0064] The rotary piston rotary seal section 1002 divides the oil chamber 14 into a left oil chamber 1401 and a right oil chamber 1402 . The left oil chamber 1401 is connected to the left oil hole 2 , and the right oil chamber 1402 is connected to the right oil hole 3 .

[0065] When the swing cylinder is operating, when the oil enters the left oil chamber 1401 from the left oil chamber 1401, the oil applies a thrust to the right on the rotary piston 10 under the action of pressure, and the rotary piston 10 realizes rotational translation to the right under the meshing action with the outer shell 1. While the rotary piston 10 rotates and translates to the right, the spindle 8 realizes forward rotation under the meshing action with the main shaft 8. While the main shaft 8 rotates forward, it drives the robotic arm to rotate forward. Conversely, when the oil enters the right oil chamber 1402 from the right oil chamber 1402, it eventually drives the robotic arm to rotate in the opposite direction to the left.

[0066] The compact swing hydraulic cylinder for the robot arm has multiple grooves on the outer circumference of the main shaft, which makes processing convenient and fast, and has high processing precision. This avoids the problem of difficulty in processing grooves on the outer circumference of the outer shell due to the small overall volume of the swing cylinder.

[0067] In addition, by placing a dustproof sealing ring, an oil sealing ring and a wear-resistant support pad in the groove respectively, the dustproof sealing ring and the oil sealing ring can effectively improve the sealing between the outer shell and the main shaft support sleeve, as well as between the main shaft support sleeve and the main shaft. The wear-resistant support pad can increase the wear resistance of the support between the main shaft and the main shaft support sleeve when the main shaft rotates, and at the same time ensure the smoothness of the rotational friction between the main shaft and the main shaft support sleeve, reduce the resistance when the main shaft rotates, and reduce the operating noise, thereby achieving long-term stable operation of the swing cylinder and extending its service life.

[0068] However, the above description is merely a specific embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the patent of the present invention should still fall within the scope covered by the claims of the present invention.

Claims

1. A compact swing hydraulic cylinder for a robotic arm, characterized by: An outer shell is provided, wherein a left oil hole and a right oil hole are provided on the outer shell, and a left fixed support sleeve and a right fixed support sleeve are fixedly provided on both sides of the outer circumference of the outer shell respectively; A main shaft is provided inside the outer shell, and shaft segments on both sides of the main shaft are located outside the outer shell. A main shaft left support sleeve and a main shaft right support sleeve are respectively provided between the shaft segments on both sides of the inner circumference of the outer shell and the inner circumference of the outer shell. The outer circumferences of the main shaft left support sleeve and the main shaft right support sleeve are respectively sealed and fixedly connected to the inner circumference of the outer shell, and the inner circumferences of the main shaft left support sleeve and the main shaft right support sleeve are respectively rotatably sealed and connected to the outer circumference of the main shaft; A main shaft intermediate support sleeve is provided between the main shaft left support sleeve and the main shaft right support sleeve and located inside the outer shell. The outer circumference of the main shaft intermediate support sleeve is fixedly connected to the inner circumference of the outer shell, and the inner circumference of the main shaft intermediate support sleeve is rotatably sealed with the outer circumference of the main shaft. The left side support sleeve of the main shaft and the middle support sleeve of the main shaft provide axial limiting support for the main shaft; A rotary piston is provided between the outer circumference of the main shaft and the inner circumference of the outer shell. The outer circumference and inner circumference of one side of the rotary piston are respectively engaged with the inner circumference of the outer shell and the outer circumference of the main shaft. The outer circumference and inner circumference of the other side of the rotary piston are respectively rotationally sealed with the inner circumference of the outer shell and the outer circumference of the main shaft. The rotary piston can realize axial rotation and translation between the main shaft and the outer shell, and the rotary piston can drive the main shaft to rotate while axially rotating and translating. An oil chamber is formed between the main shaft middle support sleeve, the main shaft, and the main shaft right side support sleeve. Both sides of the oil chamber are connected to the left oil hole and the right oil hole respectively.

2. The compact swing hydraulic cylinder for a robotic arm according to claim 1, characterized in that: The main shaft is provided with a first main shaft section, a second main shaft section, a third main shaft section, a fourth main shaft section, a fifth main shaft section, and a sixth main shaft section from left to right. The first and sixth main shaft segments are respectively located outside the outer shell, the second and fifth main shaft segments are respectively located on both sides of the inner circumference of the outer shell, and the third and fourth main shaft segments are respectively located in the middle of the inner circumference of the outer shell; The left side support sleeve of the main shaft is located between the second shaft section of the main shaft and the leftmost inner circumference of the outer shell, and the right side support sleeve of the main shaft is located between the fifth shaft section of the main shaft and the rightmost inner circumference of the outer shell; The outer circumferences of the second spindle section and the fifth spindle section are each provided with a plurality of grooves, wherein the plurality of grooves are respectively provided with a wear-resistant support pad, an oil sealing ring, and a dustproof sealing ring, and the wear-resistant support pad, the oil sealing ring, and the dustproof sealing ring are arranged in sequence from the inside to the outside on the outer circumferences of the second spindle section and the fifth spindle section; The outer circumferences of the left and right spindle support sleeves are each provided with a plurality of grooves, and an oil sealing ring and a dustproof sealing ring are respectively provided in the plurality of grooves. The oil sealing ring and the dustproof sealing ring are arranged in sequence from the inside to the outside on the outer circumferences of the left and right spindle support sleeves; The third shaft section of the main shaft is located on the inner side of the support sleeve on the left side of the main shaft, and the third shaft section of the main shaft extends outward to form a stepped shaft structure. The first shaft shoulder and the second shaft shoulder are respectively provided on both axial sides of the third shaft section of the stepped shaft structure; A wear-resistant support pad is provided between the position of the first shaft shoulder of the third shaft section of the main shaft and the left side support sleeve of the main shaft.

3. The compact swing hydraulic cylinder for a robot arm according to claim 2, characterized in that: The spindle intermediate support sleeve is located between the second shoulder position on the outer circumference of the third shaft section of the spindle and the inner circumference of the outer shell. The outer circumference of the spindle intermediate support sleeve is fixedly connected to the inner circumference of the outer shell. The inner circumference of the spindle intermediate support sleeve is provided with a groove. An oil sealing ring is provided in the groove. The inner circumference of the spindle intermediate support sleeve and the outer circumference of the third shaft section of the spindle are rotatably sealed by the oil sealing ring. A wear-resistant support pad is provided between the intermediate support sleeve of the main shaft and the position of the third shaft section of the main shaft located at the second shaft shoulder; The spindle left side support sleeve and the spindle middle support sleeve respectively realize axial limited rotation support for the third shaft section of the spindle through wear-resistant support pads located at the first shaft shoulder and the second shaft shoulder.

4. The compact swing hydraulic cylinder for a robot arm according to claim 3, characterized in that: The rotary piston includes a rotary piston rotation support section and a rotary piston rotation sealing section, wherein the rotary piston rotation support section is located on the left side of the rotary piston, and the rotary piston rotation sealing section is located on the right side of the rotary piston; The outer circumference of the rotary piston rotation support section is threadedly engaged with the inner circumference of the outer shell, and the inner circumference of the rotary piston rotation support section is threadedly engaged with the outer circumference of the fourth shaft segment of the main shaft; The outer circumference of the rotary piston rotary seal section is provided with a groove, and an oil sealing ring is provided in the groove. The outer circumference of the rotary piston rotary seal section and the inner circumference of the outer shell are rotary sealed by the oil sealing ring; The inner circumference of the rotary piston rotary seal section is provided with a groove, and an oil sealing ring is provided in the groove. The inner circumference of the rotary piston rotary seal section and the outer circumference of the fourth shaft section of the main shaft are rotary sealed by the oil sealing ring; The rotary sealing section of the rotary piston divides the oil chamber into a left oil chamber and a right oil chamber. The left oil chamber is communicated with the left oil hole, and the right oil chamber is communicated with the right oil hole.

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