A multi-stage central sleeve hydraulic cylinder structure that can be extended and retracted step by step

Abstract

The present invention relates to a multi-stage central sleeve hydraulic cylinder structure that can be extended and retracted step by step, including a cylinder block, multi-stage intermediate cylinder barrels, and a piston rod. Among them, the previous intermediate cylinder barrel in the multi-stage intermediate cylinder barrels is sleeved outside the subsequent intermediate cylinder barrel of the multi-stage intermediate cylinder barrels. The cylinder block is sleeved outside the first-stage intermediate cylinder barrel in the multi-stage intermediate cylinder barrels, and the last-stage intermediate cylinder barrel in the multi-stage intermediate cylinder barrels is sleeved outside the piston rod. A cylinder block sleeve that penetrates the first-stage intermediate cylinder barrel is arranged in the cylinder block. Each stage of the intermediate cylinder barrel is provided with a cylinder barrel sleeve. A first oil guiding hole is arranged on the cylinder block sleeve, and a second oil guiding hole is arranged on the cylinder barrel sleeve. A communicating oil path that cooperates with the first oil guiding hole and the second oil guiding hole is arranged at the bottom of each stage of the intermediate cylinder barrel. Each stage of the intermediate cylinder barrel and the piston rod of the present invention can be extended or retracted step by step, solving the problem that the pistons of each stage are disordered during the extension or retraction process of the multi-stage piston hydraulic in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic cylinders, and more specifically, it relates to a multi-stage central sleeve hydraulic cylinder structure that can extend and retract step by step. Background Art

[0002] A hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy and performs linear reciprocating motion (or swinging motion). Hydraulic cylinders are actuating mechanisms in some machines, mainly providing pushing and pulling forces. In some machines, long-stroke hydraulic cylinders are required, but the installation space size is limited, so multi-stage hydraulic cylinders are needed. Currently, the order of extension of the multi-stage hydraulic cylinder depends on the force on each stage piston. The stage with the greater resultant force moves first. Since the oil source flow rate is constant and the volumes of each stage are different, the movement speeds of each stage will be different. Existing multi-stage hydraulic cylinders with two or more stages have the problem of disorder. That is, when two or more multi-stage hydraulic cylinders are used simultaneously and have the same operating speed, the oil sources of the two or more multi-stage hydraulic cylinders are the same, and each stage piston is pressurized simultaneously. However, due to different resistances such as friction in the hydraulic cylinder itself, pistons with different diameters of two or more multi-stage hydraulic cylinders will operate simultaneously. Although the oil source flow rate of each stage is the same, the volume sizes are different, resulting in different extension speeds of each multi-stage hydraulic cylinder. At this time, each multi-stage hydraulic cylinder will be out of sync, which will cause uneven force on the multi-stage hydraulic cylinder, exceeding the rated load range of the multi-stage hydraulic cylinder, resulting in damage such as deformation of the multi-stage hydraulic cylinder body and damage to the seals, shortening the life of the multi-stage hydraulic cylinder or even causing it to be scrapped. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a multi-stage central sleeve hydraulic cylinder structure that can extend and retract step by step. The intermediate cylinders and the piston rod at each stage can be extended or retracted step by step, solving the problem of disorder of each stage piston during the extension or retraction of the multi-stage piston hydraulic in the existing technology.

[0004] The above technical purpose of the present invention is achieved through the following technical solutions:

[0005] A multi-stage central sleeve hydraulic cylinder structure that can extend and retract step by step, including a cylinder block, multi-stage intermediate cylinders, and a piston rod. Among them, the previous intermediate cylinder in the multi-stage intermediate cylinders is sleeved outside the subsequent intermediate cylinder in the multi-stage intermediate cylinders. The cylinder block is sleeved outside the first-level intermediate cylinder in the multi-stage intermediate cylinders, and the last-level intermediate cylinder in the multi-stage intermediate cylinders is sleeved outside the piston rod;

[0006] The outer wall of the first-stage intermediate cylinder is slidably connected to the inner wall of the cylinder block. A cylinder sleeve penetrating the first-stage intermediate cylinder is arranged in the cylinder block. The cylinder sleeve is a hollow structure and is slidably connected to the bottom of the first-stage intermediate cylinder. A rodless cavity of the cylinder block is formed between the outer wall of the bottom of the first-stage intermediate cylinder and the inner wall of the cylinder block. The cylinder block is provided with a first oil passage leading to the rodless cavity of the cylinder block and a second oil passage leading to the cylinder sleeve. The first oil passage and the second oil passage are communicated through a main oil passage, and the main oil passage is communicated with a first oil pump.

[0007] The inner wall of the previous intermediate cylinder is slidably connected to the outer wall of the next intermediate cylinder. The previous intermediate cylinder is provided with a cylinder sleeve penetrating the next intermediate cylinder. The cylinder sleeve of the previous intermediate cylinder is slidably connected to the bottom of the next intermediate cylinder. Moreover, the cylinder sleeve of the next intermediate cylinder is sleeved outside the cylinder sleeve of the previous intermediate cylinder, and the cylinder sleeve of the first-stage intermediate cylinder is sleeved outside the cylinder sleeve of the cylinder block. A rodless cavity of the cylinder sleeve is formed between the inner wall of the previous intermediate cylinder and the outer wall of the bottom of the next intermediate cylinder. The multiple cylinder sleeves are communicated with each other, and the end of the cylinder sleeve of the last-stage intermediate cylinder is sealed. The cylinder sleeve of the cylinder block is communicated with the cylinder sleeve of the first-stage intermediate cylinder.

[0008] The inner wall of the last-stage intermediate cylinder is slidably connected to the outer wall of the piston rod. The piston rod is sleeved outside the cylinder sleeve of the last-stage intermediate cylinder and is slidably connected to the cylinder sleeve. A rodless cavity of the piston is formed between the bottom of the piston rod and the inner wall of the bottom of the last-stage intermediate cylinder.

[0009] One end of the cylinder sleeve away from the bottom of the cylinder block is provided with a first oil guiding hole. Communication oil passages are provided at the bottoms of the intermediate cylinders. The communication oil passage of the first-stage intermediate cylinder cooperates with the first oil guiding hole, and the communication oil passage of the first-stage intermediate cylinder leads to the rodless cavity of the cylinder sleeve inside the first-stage intermediate cylinder. In the state where the first-stage intermediate cylinder is fully extended, the inlet of the communication oil passage of the first-stage intermediate cylinder is communicated with the first oil guiding hole. One end of the cylinder sleeve of the previous intermediate cylinder away from the previous intermediate cylinder is provided with a second oil guiding hole. The communication oil passage of the next intermediate cylinder leads to the rodless cavity of the cylinder sleeve inside the next intermediate cylinder. In the state where the next intermediate cylinder is fully extended, the communication oil passage of the next intermediate cylinder is communicated with the second oil guiding hole of the cylinder sleeve of the previous intermediate cylinder. The communication oil passage of the last-stage intermediate cylinder leads to the rodless cavity of the piston.

[0010] A rod chamber of the cylinder block is provided between the inner wall of the cylinder block and the outer wall of the first intermediate cylinder barrel. A rod chamber of the cylinder barrel is provided between the inner wall of the previous intermediate cylinder barrel and the outer wall of the subsequent intermediate cylinder barrel. A rod chamber of the piston is provided between the inner wall of the last intermediate cylinder barrel and the outer wall of the piston cylinder. Communication holes are provided at one ends of the outer walls of the intermediate cylinder barrels close to the bottom of the cylinder block. Two adjacent rod chambers of the cylinder barrels are communicated through the communication holes. The communication hole of the first intermediate cylinder barrel communicates the rod chamber of the cylinder block with the rod chamber of the cylinder barrel of the first intermediate cylinder barrel. The communication hole of the last intermediate cylinder barrel communicates the rod chamber of the cylinder barrel of the last intermediate cylinder barrel with the rod chamber of the piston. A third oil passage is provided on the side wall of the piston rod. One end of the third oil passage is always communicated with the rod chamber of the piston, and the other end of the third oil passage is communicated with the second oil pump.

[0011] In one embodiment, the number of the intermediate cylinder barrels is at least one, and the number of the intermediate cylinder barrels of the present invention can be increased according to actual needs.

[0012] In one embodiment, the number of the intermediate cylinder barrels is one. At this time, the first intermediate cylinder barrel, the last intermediate cylinder barrel, the previous intermediate cylinder barrel and the subsequent intermediate cylinder barrel are all the same intermediate cylinder barrel.

[0013] In one embodiment, the number of the intermediate cylinder barrels is two. At this time, the first intermediate cylinder barrel is the previous intermediate cylinder barrel, and the last intermediate cylinder barrel is the subsequent intermediate cylinder barrel.

[0014] In one embodiment, the intermediate cylinder barrel includes a cylinder body as a side wall and a retaining ring as a bottom. The retaining ring is threadedly connected to the cylinder body. The retaining ring is slidably connected to the cylinder barrel sleeve or the cylinder block sleeve. A communication oil passage is provided in the retaining ring. The inlet of the communication oil passage is provided on the inner wall of the retaining ring, and the outlet of the communication oil passage leads to the inside of the cylinder body connected to the retaining ring. Two groups of sealing rings are provided on the inner wall of the retaining ring, and the two groups of sealing rings are respectively located in front of and behind the inlet of the communication oil passage. When the retaining ring slides relative to the cylinder barrel sleeve or the cylinder block sleeve, the hydraulic oil in the cylinder body will not flow through the gap between the retaining ring and the cylinder barrel sleeve or the cylinder block sleeve.

[0015] In one embodiment, a first connecting portion is provided on the outer surface of the cylinder block for facilitating connection with an external device.

[0016] In one embodiment, a second connecting portion is provided at the outer end of the piston rod, and the piston rod can be connected to an external device through the second connecting portion.

[0017] In one embodiment, the length of the cylinder barrel sleeve is greater than the length of the cylinder block sleeve.

[0018] The present invention has the following beneficial effects:

[0019] Through the cooperation of the communication oil paths of each stage of intermediate cylinder barrels and the oil guiding holes of the sleeves corresponding to each stage of intermediate cylinder barrels, the present invention realizes the sequential and orderly extension of each stage of intermediate cylinder barrels and the piston rod. Through the cooperation of the rod chambers of the cylinder block, the rod chambers of multiple cylinder barrels, and the rod chambers of the pistons that are communicated in sequence, the sequential and orderly retraction of each stage of intermediate cylinder barrels and the piston rod is realized. When the flow rate and pressure of the oil source are stable, the load of the cylinder block is balanced, effectively avoiding damage to the cylinder block. When two or more multi-stage hydraulic cylinders extend simultaneously, there will be no disorder of stages, solving the problem of disorder of each stage of pistons in the prior art during the extension or retraction of multi-stage piston hydraulics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram when each stage of pistons of the present invention has not been activated;

[0021] Figure 2 is Figure 1 an enlarged schematic diagram of part A in

[0022] Figure 3 is Figure 1 an enlarged schematic diagram of part B in

[0023] Figure 4 is a schematic diagram when the first-stage piston of the present invention is fully extended;

[0024] Figure 5 is Figure 4 an enlarged schematic diagram of part C in

[0025] Figure 6 is Figure 4 an enlarged schematic diagram of part D in.

[0026] In the figure: 1 - cylinder block, 2 - first intermediate cylinder barrel, 3 - second intermediate cylinder barrel, 4 - third intermediate cylinder barrel, 5 - piston rod, 6 - retaining ring, 7 - cylinder block sleeve, 8 - first cylinder barrel sleeve, 9 - second cylinder barrel sleeve, 10 - third cylinder barrel sleeve, 11 - rod chamber of the cylinder block, 12 - rod chamber of the first cylinder barrel, 13 - rod chamber of the second cylinder barrel, 14 - rod chamber of the piston, 15 - main oil path, 16 - first oil path, 17 - second oil path, 18 - third oil path, 19 - first connecting part, 20 - second connecting part, 21 - communication oil path, 22 - first oil guiding hole, 23 - second oil guiding hole, 24 - communication hole, 25 - sealing ring. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be described in detail below with reference to the drawings and embodiments.

[0028] It should be noted that the orientation words such as "upper" and "lower" involved herein are relative to the perspective of the drawings, and are only for the convenience of description and cannot be construed as a limitation to the technical solution.

[0029] A multi-stage central sleeve hydraulic cylinder structure that can be extended and retracted step by step, including a cylinder block 1, multi-stage intermediate cylinder barrels, and a piston rod 5. Among them, the previous intermediate cylinder barrel in the multi-stage intermediate cylinder barrels is sleeved outside the subsequent intermediate cylinder barrel in the multi-stage intermediate cylinder barrels. The cylinder block 1 is sleeved outside the first-stage intermediate cylinder barrel in the multi-stage intermediate cylinder barrels, and the last-stage intermediate cylinder barrel in the multi-stage intermediate cylinder barrels is sleeved outside the piston rod 5;

[0030] The outer wall of the first-stage intermediate cylinder barrel is slidably connected to the inner wall of the cylinder block 1. A cylinder sleeve 7 that penetrates the first-stage intermediate cylinder barrel is arranged inside the cylinder block 1. The cylinder sleeve 7 is a hollow structure. The cylinder sleeve 7 is slidably connected to the bottom of the first-stage intermediate cylinder barrel. A cylinder rodless cavity is formed between the bottom outer wall of the first-stage intermediate cylinder barrel and the inner wall of the cylinder block 1. The cylinder block 1 is provided with a first oil passage 16 leading to the cylinder rodless cavity and a second oil passage 17 leading to the cylinder sleeve 7. The first oil passage 16 and the second oil passage 17 are connected through a main oil passage 15. The main oil passage 15 is connected to a first oil pump;

[0031] The inner wall of the previous intermediate cylinder barrel is slidably connected to the outer wall of the subsequent intermediate cylinder barrel. The previous intermediate cylinder barrel is provided with a cylinder barrel sleeve that penetrates the subsequent intermediate cylinder barrel. The cylinder barrel sleeve of the previous intermediate cylinder barrel is slidably connected to the bottom of the subsequent intermediate cylinder barrel. Moreover, the cylinder barrel sleeve of the subsequent intermediate cylinder barrel is sleeved outside the cylinder barrel sleeve of the previous intermediate cylinder barrel. The cylinder barrel sleeve of the first-stage intermediate cylinder barrel is sleeved outside the cylinder sleeve 7. A cylinder barrel rodless cavity is formed between the inner wall of the previous intermediate cylinder barrel and the outer wall of the bottom of the subsequent intermediate cylinder barrel. Multiple cylinder barrel sleeves are interconnected, and the end of the cylinder barrel sleeve of the last-stage intermediate cylinder barrel is sealed. The cylinder sleeve 7 is connected to the cylinder barrel sleeve of the first-stage intermediate cylinder barrel;

[0032] The inner wall of the last-stage intermediate cylinder barrel is slidably connected to the outer wall of the piston rod 5. The piston rod 5 is sleeved outside the cylinder barrel sleeve of the last-stage intermediate cylinder barrel and is slidably connected to it. A piston rodless cavity is formed between the bottom of the piston rod 5 and the bottom inner wall of the last-stage intermediate cylinder barrel;

[0033] One end of the cylinder sleeve 7 away from the bottom of the cylinder block 1 is provided with a first oil guide hole 22. A communication oil passage 21 is provided at the bottom of each intermediate cylinder barrel. The communication oil passage 21 of the first-stage intermediate cylinder barrel cooperates with the first oil guide hole 22, and the communication oil passage 21 of the first-stage intermediate cylinder barrel leads to the cylinder barrel rodless cavity inside the first-stage intermediate cylinder barrel. In the state where the first-stage intermediate cylinder barrel is fully extended, the inlet of the communication oil passage 21 of the first-stage intermediate cylinder barrel is connected to the first oil guide hole 22. One end of the cylinder barrel sleeve of the previous intermediate cylinder barrel away from the previous intermediate cylinder barrel is provided with a second oil guide hole 23. The communication oil passage 21 of the subsequent intermediate cylinder barrel leads to the cylinder barrel rodless cavity inside the subsequent intermediate cylinder barrel. In the state where the subsequent intermediate cylinder barrel is fully extended, the communication oil passage 21 of the subsequent intermediate cylinder barrel is connected to the second oil guide hole 23 of the cylinder barrel sleeve of the previous intermediate cylinder barrel. The communication oil passage 21 of the last-stage intermediate cylinder barrel leads to the piston rodless cavity;

[0034] There is a rod chamber 11 of the cylinder block between the inner wall of the cylinder block 1 and the outer wall of the first-stage intermediate cylinder barrel. There is a rod chamber of the cylinder barrel between the inner wall of the previous intermediate cylinder barrel and the outer wall of the next intermediate cylinder barrel. There is a rod chamber 14 of the piston between the inner wall of the last-stage intermediate cylinder barrel and the outer wall of the piston cylinder. At one end of the outer wall of the intermediate cylinder barrel close to the bottom of the cylinder block 1, there are communication holes 24. The rod chambers of two adjacent cylinder barrels are communicated through the communication holes 24. The communication hole 24 of the first-stage intermediate cylinder barrel communicates the rod chamber 11 of the cylinder block with the rod chamber of the cylinder barrel of the first-stage intermediate cylinder barrel. The communication hole 24 of the last-stage intermediate cylinder barrel communicates the rod chamber of the cylinder barrel of the last-stage intermediate cylinder barrel with the rod chamber 14 of the piston. On the side wall of the piston rod 5, there is a third oil passage 18. One end of the third oil passage 18 is always communicated with the rod chamber 14 of the piston, and the other end of the third oil passage 18 is communicated with the second oil pump.

[0035] Wherein, the number of the intermediate cylinder barrels is at least one, and the number of the intermediate cylinder barrels of the present invention can be increased according to actual needs.

[0036] In this embodiment, the intermediate cylinder barrel includes a cylinder body as the side wall and a retaining ring 6 as the bottom. The retaining ring 6 is threadedly connected to the cylinder body. The retaining ring 6 is slidably connected to the cylinder barrel sleeve or the cylinder block sleeve 7. A communication oil passage 21 is arranged in the retaining ring 6. The inlet of the communication oil passage 21 is arranged on the inner wall of the retaining ring 6, and the outlet of the communication oil passage 21 leads to the inside of the cylinder body connected to the retaining ring 6. Two groups of sealing rings 25 are arranged on the inner wall of the retaining ring 6, and the two groups of sealing rings 25 are respectively in front of and behind the inlet of the communication oil passage 21. When the retaining ring 6 slides relative to the cylinder barrel sleeve or the cylinder block sleeve 7, the hydraulic oil in the cylinder body will not flow through the gap between the retaining ring 6 and the cylinder barrel sleeve or the cylinder block sleeve 7.

[0037] As Figures 1-6 shown, taking the number of intermediate cylinder barrels being three as an example to illustrate the usage method of the present invention. For the convenience of description, the first intermediate cylinder barrel 2 is used to represent the first-stage intermediate cylinder barrel, the second intermediate cylinder barrel 3 is used to represent the second intermediate cylinder barrel, and the third intermediate cylinder barrel 4 is used to represent the last-stage intermediate cylinder barrel. There are two rodless chambers of the cylinder barrel and two rod chambers of the cylinder barrel between the three intermediate cylinder barrels. The two rod chambers of the cylinder barrel are distinguished by the first rod chamber 12 of the cylinder barrel and the second rod chamber 13 of the cylinder barrel, and the two rodless chambers of the cylinder barrel are distinguished by the first rodless chamber of the cylinder barrel and the second rodless chamber of the cylinder barrel. In addition, the cylinder barrel sleeves of the three intermediate cylinder barrels are also sequentially distinguished by the first cylinder barrel sleeve 8, the second cylinder barrel sleeve 9, and the third cylinder barrel sleeve 10. The usage method of the present invention is as follows:

[0038] The extending process of each stage of the intermediate cylinder barrel and the piston rod 5:

[0039] The first oil pump is connected to the main oil passage 15 of the cylinder block 1 to input hydraulic oil into the cylinder block 1. The hydraulic oil enters the rodless cavity of the cylinder block through the first oil passage 16 to push the first intermediate cylinder barrel 2 to extend outward along the cylinder block sleeve 7. At the same time, the hydraulic oil enters the cylinder block sleeve 7 through the second oil passage 17. Since the cylinder block sleeve 7, the first cylinder barrel sleeve 8, the second cylinder barrel sleeve 9 and the third cylinder barrel sleeve 10 are connected and the end of the third cylinder barrel sleeve 10 is sealed, the hydraulic oil finally reaches the third cylinder barrel sleeve 10. At this time, since the rodless cavities of the first cylinder barrel, the second cylinder barrel and the piston are all in a compressed state, the hydraulic oil entering the third cylinder barrel sleeve 10 cannot push the piston rod 5 to move on the third cylinder barrel sleeve 10. That is, the first intermediate cylinder barrel 2, the second intermediate cylinder barrel 3, the third intermediate cylinder barrel 4 and the piston rod 5 are regarded as a whole, and this whole is driven by the first intermediate cylinder barrel 2. The hydraulic oil entering the third cylinder barrel sleeve 10 can only cause relative movement between the first intermediate cylinder barrel 2 and the cylinder block sleeve 7, and the first intermediate cylinder barrel 2 extends outward.

[0040] When the first intermediate cylinder barrel 2 moves to the end of the cylinder block sleeve 7, the first intermediate cylinder barrel 2 reaches the limit position of extension. The communication oil passage 21 on the retaining ring 6 of the first intermediate cylinder barrel 2 is aligned with the first oil guiding hole 22 at the end of the cylinder block sleeve 7. The hydraulic oil in the cylinder block sleeve 7 flows through the first oil guiding hole 22 and the communication oil passage 21 and enters the rodless cavity of the first cylinder barrel to push the second intermediate cylinder barrel 3 to continue to extend forward along the first cylinder barrel sleeve 8. When the second intermediate cylinder barrel 3 moves to the limit position of extension, the communication oil passage 21 on the retaining ring 6 of the second intermediate cylinder barrel 3 is aligned with the second oil guiding hole 23 at the end of the first cylinder barrel sleeve 8. The hydraulic oil in the first cylinder barrel sleeve 8 flows through the second oil guiding hole 23 and the communication oil passage 21 and enters the rodless cavity of the second cylinder barrel to push the third intermediate cylinder barrel 4 to continue to extend forward along the second cylinder barrel sleeve 9. When the third intermediate cylinder barrel 4 moves to the limit position of extension, the communication oil passage 21 on the retaining ring 6 of the third intermediate cylinder barrel 4 is aligned with the second oil guiding hole 23 at the end of the second cylinder barrel sleeve 9. The hydraulic oil in the second cylinder barrel sleeve 9 flows through the second oil guiding hole 23 and the communication oil passage 21 and enters the rodless cavity of the piston to push the piston rod 5 to continue to extend forward along the third cylinder barrel sleeve 10 to the limit position where the piston rod 5 can extend. Thus, the present invention completes the orderly extension of each intermediate cylinder barrel and the piston rod 5.

[0041] It should be noted that the rod chambers of the cylinder block 11, the first cylinder barrel 12, the second cylinder barrel 13 and the piston 14 are connected to each other in pairs through communication holes 24, and the piston rod chamber 14 is connected to the second oil pump through the third oil passage 18. During the orderly extension of each intermediate cylinder barrel and the piston rod 5, the second oil pump is never started, and the hydraulic oil in the rod chambers of the cylinder block 11, the first cylinder barrel 12, the second cylinder barrel 13 and the piston 14 is finally discharged through the third oil passage 18. The specific process is as follows:

[0042] During the extension of the first intermediate cylinder barrel 2, the volume of the rod chamber 11 of the cylinder block gradually decreases. The hydraulic oil in the rod chamber 11 of the cylinder block enters the rod chamber 12 of the adjacent first cylinder barrel through the communication hole 24. Since the rod chamber 11 of the cylinder block, the rod chamber 12 of the first cylinder barrel, the rod chamber 13 of the second cylinder barrel, and the rod chamber 14 of the piston are in communication, the hydraulic oil in the rod chamber 11 of the cylinder block is gradually discharged. When the first intermediate cylinder barrel 2 extends to the limit position, the volume of the rod chamber 11 of the cylinder block reaches the minimum. Similarly, during the extension of the second intermediate cylinder barrel 3, the volume of the rod chamber 12 of the first cylinder barrel gradually decreases, and the hydraulic oil in the rod chamber 12 of the first cylinder barrel is gradually discharged. When the second intermediate cylinder barrel 3 extends to the limit position, the volume of the rod chamber 12 of the first cylinder barrel reaches the minimum. During the extension of the third intermediate cylinder barrel 4, the volume of the rod chamber 13 of the second cylinder barrel gradually decreases, and the hydraulic oil in the rod chamber 13 of the second cylinder barrel is gradually discharged. When the third intermediate cylinder barrel 4 extends to the limit position, the volume of the rod chamber 13 of the second cylinder barrel reaches the minimum. During the extension of the piston rod 5, the volume of the rod chamber 14 of the piston gradually decreases, and the hydraulic oil in the rod chamber 14 of the piston is gradually discharged. When the piston extends to the limit position, the volume of the rod chamber 14 of the piston reaches the minimum. At this time, the rod chamber 14 of the piston is still in communication with the third oil circuit 18.

[0043] Retraction process of each intermediate cylinder barrel and the piston rod 5:

[0044] After each intermediate cylinder barrel and the piston rod 5 are fully extended, the rod chamber 11 of the cylinder block, the rod chamber 12 of the first cylinder barrel, the rod chamber 13 of the second cylinder barrel, and the rod chamber 14 of the piston are all in the minimum compressed state.

[0045] The second oil pump is in communication with the third oil circuit 18, and injects hydraulic oil into the rod chamber 14 of the piston through the third oil circuit 18. The rod chamber 14 of the piston gradually expands, causing the piston rod 5 to retract into the third intermediate cylinder barrel 4. The hydraulic oil in the rodless chamber of the piston enters the second cylinder barrel sleeve 9 through the communication oil circuit 21 of the third intermediate cylinder barrel 4 and the second oil guiding hole 23 of the second cylinder barrel sleeve 9. Since the cylinder block sleeve 7, the first cylinder barrel sleeve 8, the second cylinder barrel sleeve 9, and the third cylinder barrel sleeve 10 are in communication, this part of the hydraulic oil enters the second oil circuit 17 through the second cylinder barrel sleeve 9 - the first cylinder barrel sleeve 8 - the cylinder block sleeve 7, and thus flows out through the main oil circuit 15.

[0046] When the piston rod 5 is fully retracted into the third intermediate cylinder 4, the volume of the piston rodless chamber is the smallest, and the volume of the piston rod chamber 14 reaches the maximum at this time, and the piston rod chamber 14 is connected with the second cylinder rod chamber 13 through the connecting hole 24 at this time, so the hydraulic oil in the piston rod chamber 14 enters the second cylinder rod chamber 13, so that the volume of the second cylinder rod chamber 13 gradually increases, pushing the third intermediate cylinder 4 to retract toward the third intermediate cylinder 4, and the hydraulic oil in the second cylinder rodless chamber flows into the first cylinder sleeve 8 through the connecting oil path 21 of the third intermediate cylinder 4 and the second oil guide hole 23 of the first cylinder sleeve 8, and then flows out through the cylinder sleeve 7, the second oil path 17 and the main oil path 15 in sequence;

[0047] When the third intermediate cylinder 4 is fully retracted into the second intermediate cylinder 3, the volume of the second cylinder rodless chamber is the smallest, and at this time the volume of the second cylinder rod chamber 13 reaches the maximum, and at this time the second cylinder rod chamber 13 is connected with the first cylinder rod chamber 12 through the through hole, so the hydraulic oil in the second cylinder rod chamber 13 enters the first cylinder rod chamber 12, so that the volume of the first cylinder rod chamber 12 gradually increases, pushing the second intermediate cylinder 3 to retract toward the first intermediate cylinder 2, and the hydraulic oil in the first cylinder rodless chamber flows to the cylinder casing 7 through the connecting oil path 21 of the second intermediate cylinder 3 and the second oil guide hole 23 of the first cylinder casing 8, and then flows out through the second oil path 17 and the main oil path 15;

[0048] When the second intermediate cylinder 3 is fully retracted into the first intermediate cylinder 2, the volume of the first cylinder rod chamber 12 reaches the maximum, and at this time the first cylinder rod chamber 12 is connected with the cylinder rod chamber 11 through the connecting hole 24, and the hydraulic oil in the first cylinder rod chamber 12 enters the cylinder rod chamber 11 to push the first intermediate cylinder 2 to be fully retracted into the cylinder body 1, and the hydraulic oil in the cylinder rodless chamber flows into the main oil circuit 15 through the first oil circuit 16 and the second oil circuit 17, and finally flows out. At this point, the present invention completes the orderly retraction of each stage of intermediate cylinders and piston rod 5.

[0049] In addition, during the extension of the second intermediate cylinder 3, the first cylinder rod chamber 12 is no longer connected to the cylinder body rod chamber 11. At this time, the cylinder body rod chamber 11 is connected to the first cylinder rodless chamber through the connecting hole 24. Since the first cylinder rodless chamber is already filled with hydraulic oil, even if the hydraulic oil in the first cylinder rodless chamber enters the cylinder body rod chamber 11, the volume of the cylinder body rod chamber 11 cannot be expanded, so the cylinder body rodless chamber will not be compressed, that is, the connection between the cylinder body rod chamber 11 and the first cylinder rodless chamber will not affect the step-by-step extension of the multi-stage piston. Similarly, during the extension of the third intermediate cylinder 4 and the piston rod 5, the connection between the first cylinder rod chamber 12 and the second cylinder rodless chamber and the connection between the second cylinder rod chamber 13 and the piston rodless chamber will not affect the step-by-step extension of the multi-stage piston, and will not affect the step-by-step extension of each intermediate cylinder and the piston rod 5.

[0050] The present invention is applicable to hydraulic cylinders with the number of intermediate cylinders greater than or equal to one. For example, when the number of the intermediate cylinders is one, at this time, the first-stage intermediate cylinder, the last-stage intermediate cylinder, the previous intermediate cylinder and the subsequent intermediate cylinder are all the same intermediate cylinder; or, when the number of the intermediate cylinders is two, at this time, the first-stage intermediate cylinder is the previous intermediate cylinder and the last-stage intermediate cylinder is the subsequent intermediate cylinder.

[0051] In this embodiment, a first connection portion 19 is provided on the outer surface of the cylinder block 1, facilitating connection with external equipment.

[0052] In this embodiment, a second connection portion 20 is provided at the outer end of the piston rod 5, and connection with external equipment can be achieved through the second connection portion 20.

[0053] In this embodiment, the length of the cylinder sleeve is greater than the length of the cylinder block sleeve 7.

[0054] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A multi-stage central sleeve hydraulic cylinder structure that can be extended and retracted step by step, characterized in that, it includes a cylinder block (1), multi-stage intermediate cylinder barrels and a piston rod (5). Among them, the previous intermediate cylinder barrel in the multi-stage intermediate cylinder barrels is sleeved outside the subsequent intermediate cylinder barrel of the multi-stage intermediate cylinder barrels. The cylinder block (1) is sleeved outside the first-stage intermediate cylinder barrel in the multi-stage intermediate cylinder barrels, and the last-stage intermediate cylinder barrel in the multi-stage intermediate cylinder barrels is sleeved outside the piston rod (5); The outer wall of the first-stage intermediate cylinder barrel is slidably connected to the inner wall of the cylinder block (1). A cylinder sleeve (7) passing through the first-stage intermediate cylinder barrel is arranged in the cylinder block (1). The cylinder sleeve (7) is a hollow structure. The cylinder sleeve (7) is slidably connected to the bottom of the first-stage intermediate cylinder barrel. A cylinder rodless cavity is formed between the bottom outer wall of the first-stage intermediate cylinder barrel and the inner wall of the cylinder block (1). The cylinder block (1) is provided with a first oil passage (16) leading to the cylinder rodless cavity and a second oil passage (17) leading to the cylinder sleeve (7). The first oil passage (16) and the second oil passage (17) are connected through a main oil passage (15). The main oil passage (15) is connected to a first oil pump; The inner wall of the previous intermediate cylinder barrel is slidably connected to the outer wall of the subsequent intermediate cylinder barrel. The previous intermediate cylinder barrel is provided with a cylinder barrel sleeve passing through the subsequent intermediate cylinder barrel. The cylinder barrel sleeve of the previous intermediate cylinder barrel is slidably connected to the bottom of the subsequent intermediate cylinder barrel, and the cylinder barrel sleeve of the subsequent intermediate cylinder barrel is sleeved outside the cylinder barrel sleeve of the previous intermediate cylinder barrel. The cylinder barrel sleeve of the first-stage intermediate cylinder barrel is sleeved outside the cylinder sleeve (7). A cylinder barrel rodless cavity is formed between the inner wall of the previous intermediate cylinder barrel and the outer wall of the bottom of the subsequent intermediate cylinder barrel. The cylinder barrel sleeves are interconnected with each other, and the end of the cylinder barrel sleeve of the last-stage intermediate cylinder barrel is sealed. The cylinder sleeve (7) is connected to the cylinder barrel sleeve of the first-stage intermediate cylinder barrel; The inner wall of the last-stage intermediate cylinder barrel is slidably connected to the outer wall of the piston rod (5). The piston rod (5) is sleeved outside the cylinder barrel sleeve of the last-stage intermediate cylinder barrel and is slidably connected to it. A piston rodless cavity is formed between the bottom of the piston rod (5) and the inner wall of the bottom of the last-stage intermediate cylinder barrel; One end of the cylinder sleeve (7) far from the bottom of the cylinder block (1) is provided with a first oil guiding hole (22). A communication oil passage (21) is provided at the bottom of each intermediate cylinder barrel. The communication oil passage (21) of the first-stage intermediate cylinder barrel cooperates with the first oil guiding hole (22), and the communication oil passage (21) of the first-stage intermediate cylinder barrel leads to the cylinder barrel rodless cavity inside the first-stage intermediate cylinder barrel. In the state where the first-stage intermediate cylinder barrel is fully extended, the inlet of the communication oil passage (21) of the first-stage intermediate cylinder barrel is connected to the first oil guiding hole (22). One end of the cylinder barrel sleeve of the previous intermediate cylinder barrel far from the previous intermediate cylinder barrel is provided with a second oil guiding hole (23). The communication oil passage (21) of the subsequent intermediate cylinder barrel leads to the cylinder barrel rodless cavity inside the subsequent intermediate cylinder barrel. In the state where the subsequent intermediate cylinder barrel is fully extended, the communication oil passage (21) of the subsequent intermediate cylinder barrel is connected to the second oil guiding hole (23) of the cylinder barrel sleeve of the previous intermediate cylinder barrel. The communication oil passage (21) of the last-stage intermediate cylinder barrel leads to the piston rodless cavity; There is a rod chamber (11) of the cylinder block between the inner wall of the cylinder block (1) and the outer wall of the first intermediate cylinder barrel. There is a rod chamber of the cylinder barrel between the inner wall of the previous intermediate cylinder barrel and the outer wall of the next intermediate cylinder barrel. There is a rod chamber (14) of the piston between the inner wall of the last intermediate cylinder barrel and the outer wall of the piston cylinder. Communication holes (24) are provided at one end of the outer wall of the intermediate cylinder barrel close to the bottom of the cylinder block (1). The rod chambers of two adjacent cylinder barrels are communicated through the communication holes (24). The communication hole (24) of the first intermediate cylinder barrel communicates the rod chamber (11) of the cylinder block with the rod chamber of the cylinder barrel of the first intermediate cylinder barrel. The communication hole (24) of the last intermediate cylinder barrel communicates the rod chamber of the cylinder barrel of the last intermediate cylinder barrel with the rod chamber (14) of the piston. A third oil passage (18) is provided on the side wall of the piston rod (5). One end of the third oil passage (18) is always communicated with the rod chamber (14) of the piston, and the other end of the third oil passage (18) is communicated with a second oil pump; The intermediate cylinder barrel includes a cylinder body as the side wall and a retaining ring (6) as the bottom. The retaining ring (6) is threadedly connected to the cylinder body. The retaining ring (6) is slidably connected to a cylinder barrel sleeve or a cylinder block sleeve (7). A communication oil passage (21) is provided inside the retaining ring (6). The inlet of the communication oil passage (21) is provided on the inner wall of the retaining ring (6). The outlet of the communication oil passage (21) leads to the inside of the cylinder body connected to the retaining ring (6). Two groups of sealing rings (25) are provided on the inner wall of the retaining ring (6). The two groups of sealing rings (25) are respectively located in front of and behind the inlet of the communication oil passage (21); The length of the cylinder barrel sleeve is greater than the length of the cylinder block sleeve (7).

2. The structure of a multi-stage center sleeve hydraulic cylinder capable of extending and retracting step by step as described in claim 1, characterized in that, The number of the intermediate cylinder barrels is at least one.

3. The structure of a multi-stage center sleeve hydraulic cylinder capable of extending and retracting step by step as described in claim 2, characterized in that, The number of the intermediate cylinder barrels is one. At this time, the first intermediate cylinder barrel, the last intermediate cylinder barrel, the previous intermediate cylinder barrel and the next intermediate cylinder barrel are all the same intermediate cylinder barrel.

4. The structure of a multi-stage center sleeve hydraulic cylinder capable of extending and retracting step by step as described in claim 2, characterized in that, The number of the intermediate cylinder barrels is two. At this time, the first intermediate cylinder barrel is the previous intermediate cylinder barrel, and the last intermediate cylinder barrel is the next intermediate cylinder barrel.

5. The structure of a multi-stage center sleeve hydraulic cylinder capable of extending and retracting step by step as described in claim 1, characterized in that, A first connecting portion (19) is provided on the outer surface of the cylinder block (1) for facilitating connection with external equipment.

6. The structure of a multi-stage center sleeve hydraulic cylinder capable of extending and retracting step by step as described in claim 5, characterized in that, A second connecting portion (20) is provided at the outer end of the piston rod (5). The external equipment can be connected through the second connecting portion (20).

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