High-precision hollow multi-stage electric cylinder

Abstract

The application discloses a high-precision hollow multi-stage electric cylinder, which comprises a multi-stage telescopic pipe assembly, the multi-stage telescopic pipe assembly comprises a rough-stage telescopic pipe and a fine-stage telescopic pipe which is slidably arranged in the rough-stage telescopic pipe, and at least one set of self-adapting rigidity reinforcing mechanism is arranged at the end of the rough-stage telescopic pipe, the self-adapting rigidity reinforcing mechanism comprises first, second, third and fourth slide rings which are slidably connected in sequence from top to bottom and have the same height, the fourth slide ring is fixedly connected with the rough-stage telescopic pipe, guide rods are fixedly arranged at the bottom of the first, second and third slide rings, guide holes are arranged in the second, third and fourth slide rings and are used for allowing the guide rods to slide therethrough, clamping plates are fixedly arranged at the bottom of the guide rods, clamping grooves which are matched with the clamping plates are formed in the bottom of the guide holes, and locking mechanisms are arranged at the two sides of the clamping grooves.

Description

Technical Field

[0001] This invention relates to the field of precision transmission and automation technology, specifically a high-precision hollow multi-stage electric cylinder. Background Technology

[0002] High-precision hollow multi-stage electric cylinders can achieve ultra-long strokes within a compact retraction length. Their hollow structure facilitates wiring, air blowing, or vacuum adsorption, making them widely used in industrial robots, semiconductor equipment, and aerospace. However, existing multi-stage electric cylinders suffer from the following drawbacks: when the thin telescopic tube extends significantly, the stiffness at the connection point decreases considerably due to the fit clearance between each sleeve and the cantilever beam effect, leading to end-effector swaying and vibration, severely affecting positioning accuracy and load-bearing capacity. Existing solutions often employ electrically controlled trigger-type reinforcement mechanisms, which not only increase the complexity of the control system but also make it difficult to guarantee reliability in harsh environments such as strong electromagnetic interference and high temperatures.

[0003] Therefore, it is necessary to provide a high-precision hollow multi-stage electric cylinder to solve the problems mentioned in the background art. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a high-precision hollow multi-stage electric cylinder, comprising a multi-stage telescopic tube assembly, wherein the multi-stage telescopic tube assembly comprises at least two telescopic tubes nested together, namely a coarse-stage telescopic tube and a fine-stage telescopic tube slidably disposed inside the coarse-stage telescopic tube, and further comprising at least one adaptive stiffness enhancement mechanism, wherein the adaptive stiffness enhancement mechanism is disposed at the end of the coarse-stage telescopic tube, and comprises a first slip ring, a second slip ring, a third slip ring, and a fourth slip ring of equal height slidably connected from top to bottom, and the fourth slip ring is fixedly connected to the coarse-stage telescopic tube; a guide rod is fixedly disposed at the bottom of the first slip ring, the second slip ring, and the third slip ring; a guide hole is provided through the second slip ring, the third slip ring, and the fourth slip ring for the guide rod to slide through; a retaining plate is fixedly disposed at the bottom of the guide rod; a retaining groove adapted to the retaining plate is opened at the bottom of the guide hole; locking mechanisms are provided on both sides of the retaining groove; and receiving grooves for accommodating the retaining plate and the guide rod are opened on the third slip ring and the fourth slip ring.

[0005] Preferably, the axial height of the adaptive stiffness enhancement mechanism in the fully contracted state is 1 to 1.2 times the diameter of the coarse-stage telescopic tube, and the axial height in the fully extended state is 2 to 2.5 times the diameter of the coarse-stage telescopic tube.

[0006] Preferably, the locking mechanism includes a locking block slidably disposed on one side of the slot, and a plurality of push rods fixedly disposed on the top of the third slip ring and the fourth slip ring. The bottom of the second slip ring and the third slip ring are provided with a plurality of insertion holes for the push rods to be slidably inserted. A push rod is slidably disposed in the insertion hole, and a spring is disposed between the push rod and the bottom of the insertion hole.

[0007] Preferably, the card block has a through groove, and the side of the through groove near the card slot has an upward inclined first slope. A boss is fixedly provided at the top of the end of the card block away from the card slot, and one end of the boss extends to the middle of the through groove and has a downward inclined second slope.

[0008] Preferably, the card plate has an annular groove, and the card block can slide into the annular groove to form a lock.

[0009] Preferably, both the push rod and the push rod are semi-cylindrical, with their semi-cylindrical surfaces facing the second inclined surface and the first inclined surface, respectively. The top of the push rod is provided with a push block having a bidirectional conical pushing surface. The push block is configured such that: when the push rod slides into the insertion hole, the push rod can push the push rod upward and compress the spring, while the top of the push block contacts the second inclined surface and pushes the locking block out of the annular groove; when the push rod is out of the insertion hole, the bottom of the push block contacts the first inclined surface and pushes the locking block into the annular groove, while the push rod resets and slides into the locking groove under the action of the spring.

[0010] Preferably, the length of the guide rod at the bottom of the first slip ring and the second slip ring is a multiple of the height of a single slip ring, the length of the guide rod at the bottom of the third slip ring is equal to the height of a single slip ring, and the height of a single slip ring is 0.6 to 0.7 times the diameter of the coarse-stage telescopic tube.

[0011] Preferably, annular permanent magnets are embedded on the adjacent contact surfaces of the first slip ring, the second slip ring, the third slip ring, and the attraction forces between the annular permanent magnets satisfy F1 < F2 < F3, where F1 is the attraction force between the first slip ring and the second slip ring, F2 is the attraction force between the second slip ring and the third slip ring, and F3 is the attraction force between the third slip ring and the fourth slip ring.

[0012] Preferably, the first slip ring protrudes from the upper end face of the coarse-stage telescopic tube, and its inner sidewall is attached to the outer sidewall of the fine-stage telescopic tube. Multiple guide grooves are formed axially on the inner side of the first slip ring and the coarse-stage telescopic tube. A guide block adapted to the multiple guide grooves is fixedly provided on the bottom outer sidewall of the fine-stage telescopic tube. A pressure ring covering the guide groove is fixedly provided on the top of the first slip ring. A pressure groove is formed on the top of the pressure ring. A limit ring is fixedly provided on the top outer sidewall of the fine-stage telescopic tube. The limit ring can slide and engage in the pressure groove.

[0013] Compared with the prior art, the present invention provides a high-precision hollow multi-stage electric cylinder, which has the following beneficial effects:

[0014] First, the stiffness is significantly improved: after the sleeve is unfolded, it forms a rigid cylinder with a length of 2 to 2.5 times the pipe diameter, which greatly improves the bending stiffness of the electric cylinder and effectively suppresses the bending deformation and vibration at the root of the thin tube.

[0015] Secondly, it has a compact structure and high space utilization: the sleeve shrinkage height is only 1 to 1.2 times the diameter of the thick pipe, which effectively reduces the impact on the installation size and stroke of the electric cylinder.

[0016] Third, it features a purely mechanical response and high reliability: the entire process of extension, locking, and unlocking requires no external electrical control or sensors, and is automatically completed solely by mechanical linkage and magnetic gradient, making it suitable for harsh environments such as strong electromagnetic interference and high temperatures.

[0017] Fourth, precise sequence control: The magnetic gradient ensures that the slip rings extend sequentially from the top to the bottom, and in conjunction with the locking mechanism, they retract sequentially from the bottom to the top when retracting, thus effectively preventing jamming. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the adaptive stiffness enhancement mechanism in this invention;

[0020] Figure 3 This is a schematic diagram of the structure of the third slip ring in this invention. Figure 1 ;

[0021] Figure 4 This is a schematic diagram of the structure of the third slip ring in this invention. Figure 2 ;

[0022] Figure 5 for Figure 4 Enlarged schematic diagram of section A in the middle;

[0023] Figure 6 This is a schematic diagram of the card block structure in this invention. Figure 1 ;

[0024] Figure 7 This is a schematic diagram of the card block structure in this invention. Figure 2 ;

[0025] In the diagram: 1. Coarse-stage telescopic tube; 2. Fine-stage telescopic tube; 3. Adaptive stiffness enhancement mechanism; 31. First slip ring; 311. Pressure ring; 312. Pressure groove; 32. Second slip ring; 33. Third slip ring; 34. Fourth slip ring; 35. Guide rod; 351. Clamping plate; 352. Annular groove; 36. Guide hole; 361. Clamping groove; 37. Locking mechanism; 38. Receiving groove; 371. Clamping block; 372. Push rod; 373. Insertion hole; 374. Push rod; 375. Through groove; 376. Boss; 377. First inclined surface; 378. Second inclined surface; 379. Push block. Detailed Implementation

[0026] Please see Figures 1 to 7 In this embodiment of the invention, a high-precision hollow multi-stage electric cylinder includes a coarse-stage telescopic tube 1, a fine-stage telescopic tube 2 slidably disposed inside the coarse-stage telescopic tube 1, and an adaptive stiffness enhancement mechanism 3 disposed at the end of the coarse-stage telescopic tube 1.

[0027] The adaptive stiffness enhancement mechanism 3 includes a first slip ring 31, a second slip ring 32, a third slip ring 33 and a fourth slip ring 34 that are slidably connected from top to bottom. The four slip rings have equal heights. The fourth slip ring 34 is fixedly connected to the outer side of the end of the thick-stage telescopic tube 1, forming the fixed foundation of the entire mechanism.

[0028] On the bottom end faces of the first slip ring 31, the second slip ring 32 and the third slip ring 33, six guide rods 35 are evenly and fixedly arranged in the circumferential direction; wherein, the length of the guide rod 35 at the bottom of the first slip ring 31 and the second slip ring 32 is twice the height of a single slip ring, and the length of the guide rod 35 at the bottom of the third slip ring 33 is equal to the height of a single slip ring.

[0029] The second slip ring 32, the third slip ring 33 and the fourth slip ring 34 are respectively provided with guide holes 36 for the guide rod 35 to slide through; the inner wall of the guide hole 36 is fitted with a self-lubricating copper-based bushing to ensure smooth sliding and reduce wear.

[0030] A disc-shaped clamping plate 351 is fixedly provided at the bottom of the guide rod 35, and the outer diameter of the clamping plate 351 is larger than the diameter of the guide rod 35; a groove 361 adapted to the shape of the clamping plate 351 is opened at the bottom of the guide hole 36; locking mechanisms 37 are symmetrically arranged on both sides of the groove 361.

[0031] The third slip ring 33 and the fourth slip ring 34 are provided with receiving grooves 38 for accommodating the clamping plate 351 and the guide rod 35 in the retracted state; when the sleeve is fully retracted, the guide rods 35 and the clamping plate 351 at each stage are respectively stored in the corresponding receiving grooves 38, ensuring that the overall structure is compact.

[0032] In this embodiment, the locking mechanism 37 includes a locking block 371 slidably disposed on one side of the slot 361, and a plurality of push rods 372 fixedly disposed on the top of the third slip ring 33 and the fourth slip ring 34.

[0033] The card block 371 is generally rectangular in shape, with a through groove 375 in the middle. The through groove 375 has an upward inclined first slope 377 on the side near the card slot 361. A boss 376 is integrally formed on the top of the end of the card block 371 away from the card slot 361. One end of the boss 376 extends to the middle of the through groove 375, and the extended end has a downward inclined second slope 378.

[0034] The outer peripheral wall of the card plate 351 is provided with an annular groove 352. When the card block 371 slides into the annular groove 352, the card plate 351 is locked in the card groove 361, realizing a rigid connection between the guide rod 35 and the slip ring.

[0035] On the bottom end faces of the second slip ring 32 and the third slip ring 33, a plurality of insertion holes 373 are provided corresponding to the position of the push rod 372; a push rod 374 is slidably arranged in the insertion hole 373, and a return spring is provided between the push rod 374 and the bottom of the insertion hole 373.

[0036] The top of the push rod 372 is fixedly provided with a push block 379, which has a bidirectional conical push surface, that is, the upper surface is a conical surface and the lower surface is also a conical surface.

[0037] In this embodiment, annular permanent magnets are embedded on the adjacent contact surfaces of the first slip ring 31, the second slip ring 32, the third slip ring 33, and the fourth slip ring 34, and the attraction forces between the annular permanent magnets satisfy F1 < F2 < F3, where F1 is the attraction force between the first slip ring 31 and the second slip ring 32, F2 is the attraction force between the second slip ring 32 and the third slip ring 33, and F3 is the attraction force between the third slip ring 33 and the fourth slip ring 34.

[0038] In this embodiment, the first slip ring 31 protrudes from the upper end face of the coarse telescopic tube 1, and its inner sidewall slides against the outer sidewall of the fine telescopic tube 2; multiple guide grooves are opened along the axial direction on the inner side of the first slip ring 31 and the coarse telescopic tube 1, and a guide block adapted to the guide groove is fixedly provided on the bottom outer sidewall of the fine telescopic tube 2 to transmit torque and prevent the fine telescopic tube 2 from rotating.

[0039] A pressure ring 311 is fixedly provided on the top of the first slip ring 31, and the pressure ring 311 covers the upper opening of the guide groove; an annular pressure groove 312 is provided on the top of the pressure ring 311, and a limit ring is fixedly provided on the top outer wall of the thin telescopic tube 2, which can slide into the pressure groove 312.

[0040] During implementation, when the electric cylinder is in the retracted state, the thin telescopic tube 2 is completely retracted into the coarse telescopic tube 1; the four slip rings of the adaptive stiffness enhancement mechanism 3 overlap and contract under the magnetic adsorption, and the total axial height is 1 to 1.2 times the diameter of the coarse telescopic tube 1; the guide rods 35 and the clamping plates 351 of each stage are respectively housed in the corresponding receiving slots 38, and the overall structure is compact and does not occupy additional axial space.

[0041] When the electric cylinder begins to extend, the thin telescopic tube 2 gradually extends from the coarse telescopic tube 1 under the action of the drive mechanism; due to the cooperation between the guide block and the guide groove, the thin telescopic tube 2 maintains linear motion and does not rotate.

[0042] When the guide block at the bottom of the thin telescopic tube 2 contacts the bottom of the pressure ring 311, the thin telescopic tube 2 begins to extend along with the first slip ring 31 through the pressure ring 311; at this time, the engagement action is completed.

[0043] The thin telescopic tube 2 continues to extend, and the pressure ring 311 pulls the first slip ring 31 to move upward. Since the magnetic force between the first slip ring 31 and the second slip ring 32 is the smallest, the first slip ring 31 first overcomes the magnetic force and separates from the second slip ring 32, and drives the guide rod 35 at its bottom to slide out from the receiving groove 38 of the third slip ring 33.

[0044] When the first slip ring 31 is pulled to its limit position, its bottom locking plate 351 enters the bottom of the locking groove 361 of the second slip ring 32 and is thus limited. At this time, as the thin telescopic tube 2 continues to extend, the first slip ring 31 will drive the second slip ring 32 to slide together. When the second slip ring slides, the push rod 372 at the top of the third slip ring 33 will disengage from the insertion hole at the bottom of the second slip ring 32, and at the same time drive the push block 379 to slide down and push the locking block in the second slip ring 32 into the annular groove 352 of the locking plate 35, so that the locking plate 35 is locked in the locking groove 361, that is, the first slip ring 31 and the second slip ring 32 are locked.

[0045] When the first slip ring 31 and the second slip ring 32 are locked, the pulling force of the thin telescopic tube 2 is transmitted to the second slip ring 32 through the first slip ring 31, and continues to pull the second slip ring 32 upward; the second slip ring 32 overcomes the magnetic force between itself and the third slip ring 33, and the guide rod 35 at its bottom slides out from the receiving groove 38 of the fourth slip ring 34.

[0046] When the second slip ring 32 is pulled to its limit position, its locking plate 351 enters the locking groove 361 of the third slip ring 33, and the locking mechanism operates in the same way to lock the second slip ring 32 and the third slip ring 33 into a rigid connection.

[0047] At this time, the third slip ring 33 and the fourth slip ring 34 are in a sliding connection without locking, and the magnetic force between them is at its maximum. When the pulling force continues to act, the third slip ring 33 overcomes the magnetic force and is pulled out until all slip rings are fully extended.

[0048] Finally, the adaptive stiffness enhancement mechanism 3 fully unfolds, and the total axial height reaches 2 to 2.5 times the diameter of the coarse-stage telescopic tube 1, forming a rigid cylindrical structure that wraps around the root of the fine-stage telescopic tube 2, which significantly improves the bending stiffness at the connection.

[0049] It should be noted that there is a height difference between the first inclined plane 377 and the second inclined plane 378. Both the push rod 372 and the push rod 374 are semi-cylindrical rods, and their respective semi-cylindrical surfaces face the second inclined plane 377 and the first inclined plane 378, respectively. This means that when the push rod 372 passes through the through groove 375, the push block 379 will push the locking block 371 to slide. After sliding, the second inclined plane 377 will contact the semi-cylindrical surface of the push rod 372, thus restricting the locking block 371. At the same time, the sliding of the locking block 371 will cause the first inclined plane 377 to slide together. At this time, the first inclined plane 377 will slide exactly below the push block 379, so that when the push block 379 slides down, it can slide along the first inclined plane 377 and push the locking block 371 to slide again. The semi-cylindrical design of the push block 379 makes way for the first inclined surface 377. Correspondingly, when the push block 379 slides down and pushes the locking block 371 to slide, the second inclined surface 378 will slide back to above the push block 379. Since there is a height difference between the first inclined surface 377 and the second inclined surface 378, the push block 379 has already left the sliding range of the second inclined surface 378 and will not cause motion interference. Similarly, when the push rod 372 slides out of the insertion hole 373, the push rod 374 will slide out, and its semi-cylindrical surface will fit against the first inclined surface 377, which will also restrict the locking block 371 and prevent the locking block 371 from leaving the annular groove 352. Moreover, its semi-cylindrical design makes way for the second inclined surface 378 and prevents motion interference.

[0050] When the electric cylinder retracts, the thin telescopic tube 2 begins to move downwards; the limiting ring at the top of the thin telescopic tube 2 first contacts the bottom of the pressure groove 312 of the pressure ring 311, pushing the first slip ring 31 downwards. At this time, the downward pressure is transmitted sequentially through the rigidly connected slip rings; since the third slip ring 33 and the fourth slip ring 34 are slidably connected and not locked, and the magnetic force between them is the greatest, the third slip ring 33 slides downwards first.

[0051] When the third slip ring 33 slides into contact with the fourth slip ring 34, the push rod 372 at the top of the fourth slip ring 34 slides into the insertion hole 373 of the third slip ring 33. At this time, the push block 379 pushes the push rod 374 to retract, and at the same time, the push block 379 pushes the locking block 371 in the third slip ring 33, causing it to rotate and disengage from the annular groove 352 on the locking plate 35 in the second slip ring 32. This allows the guide rod 35 on the second slip ring 32 to slide into the receiving groove 38 in the fourth slip ring 34. At the same time, the second slip ring 32 slides into contact with the third slip ring 33. Similarly, when the second slip ring 32 contacts the third slip ring 33, the guide rod 35 on the first slip ring 31 unlocks from the second slip ring 32. Then, the first slip ring 31 slides into contact with the second slip ring 32. Finally, all slip rings are completely retracted and reset under the combined action of the pressure and magnetic attraction of the telescopic tube 2, waiting for the next trigger.

[0052] In summary, the present invention provides a high-precision hollow multi-stage electric cylinder, in which a four-stage slip ring sleeve is provided at the end of the coarse-stage telescopic tube. Each stage of slip ring is slidably connected by a guide rod, and a magnetic gradient is provided between adjacent slip rings. After the slip rings are in position, they are rigidly locked by a clamping plate and a locking mechanism. During operation, the fine-stage telescopic tube extends to the trigger position and drives the first slip ring to move. Under the action of the magnetic gradient, the slip rings extend sequentially from top to bottom and lock step by step, finally forming a rigid cylinder with a length of 2 to 2.5 times the tube diameter to wrap around the root of the fine tube. When retracting, the fine-stage telescopic tube is compressed downward, and the slip rings unlock and reset sequentially from bottom to top. The entire process does not require external electrical control and is completed automatically by mechanical linkage, which significantly improves the bending stiffness of the connection and thus effectively improves the precision of the electric cylinder.

[0053] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-precision hollow multi-stage electric cylinder, comprising a multi-stage telescopic tube assembly, wherein the multi-stage telescopic tube assembly comprises at least two interlocking telescopic tubes, namely a coarse telescopic tube (1) and a fine telescopic tube (2) slidably disposed inside the coarse telescopic tube (1), characterized in that, It also includes at least one adaptive stiffness enhancement mechanism (3), which is disposed at the end of the coarse-stage telescopic tube (1). It includes a first slip ring (31), a second slip ring (32), a third slip ring (33), and a fourth slip ring (34) of equal height that are slidably connected from top to bottom. The fourth slip ring (34) is fixedly connected to the coarse-stage telescopic tube (1). The bottom of the first slip ring (31), the second slip ring (32), and the third slip ring (33) are all fixedly provided with guide rods (35). The second slip ring... (32) The third slip ring (33) and the fourth slip ring (34) are both provided with guide holes (36) through which the guide rod (35) slides. A card plate (351) is fixedly provided at the bottom of the guide rod (35). A slot (361) adapted to the card plate (351) is opened at the bottom of the guide hole (36). Locking mechanisms (37) are provided on both sides of the slot (361). A receiving groove (38) for accommodating the card plate (351) and the guide rod (35) is opened on the third slip ring (33) and the fourth slip ring (34).

2. The high-precision hollow multi-stage electric cylinder according to claim 1, characterized in that, The axial height of the adaptive stiffness enhancement mechanism (3) in the fully contracted state is 1 to 1.2 times the diameter of the coarse telescopic tube (1), and the axial height in the fully extended state is 2 to 2.5 times the diameter of the coarse telescopic tube (1).

3. A high-precision hollow multi-stage electric cylinder according to claim 1, characterized in that, The locking mechanism (37) includes a locking block (371) slidably disposed on one side of the slot (361), and a plurality of push rods (372) fixedly disposed on the top of the third slip ring (33) and the fourth slip ring (34). The bottom of the second slip ring (32) and the third slip ring (33) are provided with a plurality of insertion holes (373) for the push rods (372) to slide into. A push rod (374) is slidably disposed in the insertion hole (373), and a spring is disposed between the push rod (374) and the bottom of the insertion hole (373).

4. A high-precision hollow multi-stage electric cylinder according to claim 3, characterized in that, The card block (371) is provided with a through groove (375). The through groove (375) is provided with an upward inclined first slope (377) on the side near the card slot (361). A boss (376) is fixedly provided at the top of the end of the card block (371) away from the card slot (361). One end of the boss (376) extends to the middle of the through groove (375) and is provided with a downward inclined second slope (378).

5. A high-precision hollow multi-stage electric cylinder according to claim 4, characterized in that, The card plate (351) has an annular groove (352), and the card block (371) can slide into the annular groove (352) to form a lock.

6. A high-precision hollow multi-stage electric cylinder according to claim 5, characterized in that, Both the push rod (372) and the push rod (374) are semi-cylindrical, with their semi-cylindrical surfaces facing the second inclined surface (378) and the first inclined surface (377), respectively. The top of the push rod (372) is provided with a push block (379) having a bidirectional conical pushing surface. The push block (379) is configured such that when the push rod (372) slides into the insertion hole (373), the push rod (372) can push the push rod (374) upwards and compress the spring. When the top of the push block (379) contacts the second inclined surface (378) and pushes the locking block (371) out of the annular groove (352); when the push rod (372) disengages from the insertion hole (373), the bottom of the push block (379) contacts the first inclined surface (377) and pushes the locking block (371) into the annular groove (352), while the push rod (374) resets and slides into the locking groove (361) under the action of the spring.

7. A high-precision hollow multi-stage electric cylinder according to claim 1, characterized in that, The length of the guide rod (35) at the bottom of the first slip ring (31) and the second slip ring (32) is twice the height of a single slip ring. The length of the guide rod (35) at the bottom of the third slip ring (33) is equal to the height of a single slip ring, and the height of a single slip ring is 0.6 to 0.7 times the diameter of the coarse telescopic tube (1).

8. A high-precision hollow multi-stage electric cylinder according to claim 1, characterized in that, The adjacent contact surfaces of the first slip ring (31), the second slip ring (32), the third slip ring (33) and the fourth slip ring (34) are all embedded with ring permanent magnets, and the attraction force between the ring permanent magnets satisfies F1 < F2 < F3, where F1 is the attraction force between the first slip ring (31) and the second slip ring (32), F2 is the attraction force between the second slip ring (32) and the third slip ring (33), and F3 is the attraction force between the third slip ring (33) and the fourth slip ring (34).

9. A high-precision hollow multi-stage electric cylinder according to claim 1, characterized in that, The first slip ring (31) protrudes from the upper end face of the coarse telescopic tube (1), and its inner side wall is attached to the outer side wall of the fine telescopic tube (2). Multiple guide grooves are opened along the axial direction on the inner side of the first slip ring (31) and the coarse telescopic tube (1). A guide block adapted to the multiple guide grooves is fixedly provided on the bottom outer side wall of the fine telescopic tube (2). A pressure ring (311) covering the guide groove is fixedly provided on the top of the first slip ring (31). A pressure groove (312) is opened on the top of the pressure ring (311). A limit ring is fixedly provided on the top outer side wall of the fine telescopic tube (2). The limit ring can slide into the pressure groove (312).

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