A super-large tonnage combined type self-locking cylinder at any position

Abstract

The present invention relates to the technical field of hydraulic cylinders, and specifically to an ultra-large tonnage combined type self-locking cylinder at any position, comprising a cylinder body, a main cylinder barrel is provided in the cylinder body, a piston rod is slidably installed in the main cylinder barrel, an oil inlet groove 1 and an oil inlet groove 2 are respectively provided at both ends of the main cylinder barrel, and a locking assembly is also included, the locking assembly comprises a secondary cylinder barrel arranged inside the cylinder body and coaxial with the piston rod and a sealing sleeve rotatably arranged on the secondary cylinder barrel, a secondary piston is provided in the secondary cylinder barrel, and the sealing sleeve and the secondary piston are connected by a connecting piece, and the connecting piece is used to drive the sealing sleeve to rotate to close one end of the main cylinder barrel provided with the oil inlet groove 2 when the secondary piston moves toward the main cylinder barrel. The present invention does not need to limit the pressure in the hydraulic oil pipe for a long time to limit the position of the piston rod, and effectively prevents the situation where the piston rod is locked unstably due to oil leakage in the oil pipe. By guiding the rotation of the sealing sleeve to make the liquid inlet hole and the groove 2 misaligned, the position of the piston rod when locked is not affected, the error is reduced, and the locking accuracy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic cylinders, and in particular to an ultra-large tonnage combined type arbitrary position self-locking cylinder. Background Art

[0002] A hydraulic cylinder is an energy transfer device that converts liquid pressure into reciprocating linear mechanical motion. With the expansion of application areas, users are increasingly using hydraulic cylinders in a wide range of application scenarios, including the cylinder locking function. The so-called locking cylinder pushes the cylinder piston rod to a specified point under the action of hydraulic pressure and maintains the position under load. Traditional cylinders usually apply a certain pressure to the rod chamber and the rodless chamber to keep the cylinder piston and piston rod in a predetermined position. The biggest problem with this method is that during the pressure-maintaining positioning process, the rod chamber and the rodless chamber have pressure at the same time, which can easily cause a cross-chamber phenomenon. In addition, the two chambers are pressurized together, which increases the load on the hydraulic system, and also places high requirements on the reliability and degree of automation of the hydraulic system.

[0003] With the development of technology, self-locking cylinders have appeared in the field of hydraulic cylinders. For example, the China Patent Network has disclosed a publication number of CN106499696B, which is called a closed self-locking cylinder, including a cylinder body and an inner cylinder sleeve. The piston is built into the inner cylinder sleeve. The inner diameter of the inner cylinder sleeve matches the outer diameter of the piston. The outer wall of the inner cylinder sleeve is provided with a circular fixing device, and a sealing ring is nested circumferentially to match the inner wall gap of the cylinder body. The front end of the inner cylinder sleeve is connected to the front cylinder cover, and a distance is left between the rear end and the rear cylinder cover, and a locking piston is also provided between the two. The locking piston is cylindrical, and its diameter matches the inner diameter of the cylinder body. The thickness of the locking piston is smaller than the distance between the rear end of the inner cylinder sleeve and the rear cylinder cover. A propulsion device is also provided between the locking piston and the rear cylinder cover, which can be locked by the locking piston when the piston rod extends to any length outside the cylinder body. After locking, the cylinder does not need to consider the pressure of the rod chamber and the rodless chamber, and only needs to maintain the pressure of the propulsion device.

[0004] In the above-mentioned public documents, when the piston rod extends out of the cylinder body to any length, hydraulic oil is injected into the locking oil port to push the locking piston to seal the rod chamber, thereby locking the piston rod at any position. Although the cylinder does not need to consider the pressure of the rod chamber and the rodless chamber after locking, it is necessary to give the locking piston pressure to maintain the advancement, which in disguise converts the pressure of the rod chamber and the rodless chamber of the cylinder into the pressure of the locking chamber. On the other hand, during the movement of the locking piston, the volume of the hydraulic oil in the rod chamber and the rodless chamber in the cylinder will be compressed, which will easily drive the piston rod to move, resulting in an increase in error in the process of locking the piston rod and reducing the locking accuracy. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides an ultra-large tonnage combined arbitrary position self-locking cylinder, which can effectively solve the problem in the prior art that the piston rod is easily moved when locking the piston rod, thereby increasing the locking error.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides an ultra-large tonnage combined type arbitrary position self-locking oil cylinder, comprising a cylinder body, a main cylinder barrel is arranged in the cylinder body, a piston rod is slidably installed in the main cylinder barrel, and an oil inlet groove 1 and an oil inlet groove 2 are respectively arranged at two ends of the main cylinder barrel, and further comprising:

[0008] A locking assembly for limiting the movement of a piston rod, the locking assembly comprising a secondary cylinder barrel arranged inside a cylinder body and coaxial with the piston rod, and a sealing sleeve rotatably arranged on the secondary cylinder barrel for closing the second oil inlet groove, a secondary piston being arranged inside the secondary cylinder barrel, and the sealing sleeve and the secondary piston being connected by a connecting piece, the connecting piece being used for driving the sealing sleeve to rotate to close one end of the main cylinder barrel provided with the second oil inlet groove when the secondary piston moves toward the main cylinder barrel.

[0009] Furthermore, the cylinder body is provided with a rod chamber oil port and a rodless chamber oil port. The rod chamber oil port is located on a side of the main cylinder barrel where an oil inlet groove 1 is provided, and the rodless chamber oil port is located on a side of the main cylinder barrel where an oil inlet groove 2 is provided. A main piston is provided at the end of the piston rod close to the rodless chamber oil port. Hydraulic oil is injected into the cylinder body through the rodless chamber oil port to drive the main piston to push the piston rod out of the cylinder body. Hydraulic oil is injected into the cylinder body through the rod chamber oil port to drive the main piston to push the piston rod to retract into the cylinder body.

[0010] Furthermore, the auxiliary cylinder is located in the cylinder body near one end of the main cylinder where an oil inlet groove 2 is provided, and the auxiliary cylinder is provided with a locking oil outlet and a locking oil inlet extending out of the cylinder body, and the locking oil outlet and the locking oil inlet are respectively located on both sides of the auxiliary cylinder.

[0011] Furthermore, the connecting member includes a connecting sleeve arranged on the auxiliary piston and a connecting column rotatably arranged on the auxiliary cylinder, the connecting column and the connecting sleeve are slidably connected, an arc guide groove is arranged on the connecting column, and a limiting column extending into the arc guide groove is arranged in the connecting sleeve.

[0012] Furthermore, the depth of the connecting sleeve is L, the distance that the secondary piston moves horizontally in the secondary cylinder is M, and L is smaller than M, so as to prevent the secondary cylinder from excessively moving and causing the locking oil outlet and the locking oil inlet to communicate with each other.

[0013] Furthermore, the angle between the initial end and the final end of the arc-shaped guide groove is 45°.

[0014] Furthermore, the sealing sleeve is provided with a plurality of groups of liquid inlet holes, and the liquid inlet holes and the second oil inlet groove on the main cylinder are staggered and distributed, and the angle between adjacent liquid inlet holes and the second oil inlet groove is 45°.

[0015] Furthermore, it also includes a sealing ball, which is movably mounted on the connecting column, and an elastic member is provided between the sealing ball and the connecting column, and the elastic member is used to always press the sealing ball against the inner wall of the cylinder body.

[0016] Furthermore, the sealing ball is arranged on the connecting column through a guide column and a guide sleeve, the diameter of the guide sleeve is larger than the diameter of the guide column, and the sealing ball is rollingly installed on the guide sleeve, a spring is sleeved on the guide column, and the spring resists the guide sleeve and the connecting column.

[0017] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects:

[0018] 1. Hydraulic oil is injected into the auxiliary cylinder through the locking oil inlet to push the auxiliary piston toward the connecting column. The sealing sleeve is guided to rotate through the limit column on the connecting sleeve and the arc-shaped guide groove on the outer peripheral surface of the connecting column, so that the liquid inlet hole on the sealing sleeve is completely misaligned with the second oil inlet groove on the main cylinder. The end of the main cylinder provided with the second oil inlet groove is closed, and the hydraulic oil between the main piston and the sealing sleeve cannot overflow. At this time, due to the incompressible nature of the hydraulic oil, the position of the piston rod is restricted and locked. There is no need to limit the pressure in the hydraulic oil pipe for a long time to limit the position of the piston rod, reduce the pressure at the connection between the oil circuit and the cylinder body, and effectively prevent the unstable locking of the piston rod caused by oil leakage in the oil pipe;

[0019] Second, the auxiliary piston pushes the connecting sleeve to cooperate with the connecting column, guiding the sealing sleeve to rotate so that the liquid inlet hole and the oil inlet groove on the main cylinder are misaligned, and then the hydraulic oil in the main cylinder is sealed to lock the piston rod position. During the sealing process, the hydraulic oil in the main cylinder will not be squeezed, and the position of the piston rod when locked will not be affected, thereby reducing errors and improving locking accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure explosion of the present invention;

[0023] Figure 3 It is a structural schematic diagram of the locking assembly of the present invention;

[0024] Figure 4 for Figure 3 The enlarged schematic diagram of point A in the middle;

[0025] Figure 5 It is a schematic cross-sectional view of the structure of the present invention when it is unlocked;

[0026] Figure 6 It is a schematic cross-sectional view of the structure of the present invention when locked;

[0027] Figure 7 It is a schematic diagram of the connection between the auxiliary piston and the connecting piece of the present invention;

[0028] Figure 8 A top view of the position of the arc-shaped guide groove on the connecting column of the present invention;

[0029] Fig. 9 It is a schematic diagram of the connection between the sealing ball and the connecting column of the present invention;

[0030] Fig.10 It is a state change diagram of the present invention.

[0031] Figure numerals: 1. cylinder body; 101. oil port of rod chamber; 102. oil port of rodless chamber; 103. locking oil outlet; 104. locking oil inlet; 11. main cylinder; 111. oil inlet groove one; 112. oil inlet groove two; 12. piston rod; 13. main piston; 2. locking assembly; 21. auxiliary cylinder; 22. auxiliary piston; 23. connecting piece; 231. connecting sleeve; 232. limiting column; 233. connecting column; 234. arc guide groove; 25. sealing ball; 26. sealing sleeve; 261. liquid inlet hole. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention will be further described below in conjunction with the embodiments.

[0034] Embodiment: A super-large tonnage combined type arbitrary position self-locking cylinder, refer to the attached Figure 1-10 ,include:

[0035] Cylinder body 1, a main cylinder barrel 11 is arranged in the cylinder body 1, and a piston rod 12 is slidably installed in the main cylinder barrel 11, and an oil inlet groove 111 and an oil inlet groove 2 112 are respectively arranged at both ends of the main cylinder barrel 11, and the oil inlet groove 111 and the oil inlet groove 2 112 are provided with multiple groups and distributed in a circular array on the main cylinder barrel 11, and the multiple groups of oil inlet grooves 111 and oil inlet grooves 2 112 are used to transport hydraulic oil into the main cylinder barrel 11 to push the piston rod 12 to extend and retract into the cylinder body 1, and the cylinder body 1 is provided with a rod chamber oil port 101 and a rodless chamber oil port 102, the rod chamber oil port 101 is located on the side of the main cylinder barrel 11 where an oil inlet groove 111 is provided, the rodless chamber oil port 102 is located on the side of the main cylinder barrel 11 where an oil inlet groove 2 112 is provided, and a main piston 13 is provided on the end of the piston rod 12 close to the rodless chamber oil port 102. Hydraulic oil is injected into the cylinder body 1 through the rodless chamber oil port 102 to drive the main piston 13 to push the piston rod 12 to move out of the cylinder body 1, and hydraulic oil is injected into the cylinder body 1 through the rod chamber oil port 101 to drive the main piston 13 to push the piston rod 12 to retract into the cylinder body 1.

[0036] Also includes:

[0037] The locking assembly 2 is used to limit the movement of the piston rod 12. The piston rod 12 moved to any position is locked by the locking assembly 2 to prevent oil leakage in the oil circuit under continuous high pressure, which causes the piston rod 12 to descend and cannot be locked. The locking assembly 2 includes a secondary cylinder 21 arranged inside the cylinder body 1 and coaxial with the piston rod 12, and a sealing sleeve 26 rotatably arranged on the secondary cylinder 21 for closing the second oil inlet groove 112. The secondary cylinder 21 is located in the cylinder body 1 near the end of the main cylinder 11 provided with the second oil inlet groove 112. The auxiliary cylinder 21 is provided with a locking oil outlet 103 and a locking oil inlet 104 extending out of the cylinder body 1, and the locking oil outlet 103 and the locking oil inlet 104 are respectively located on both sides of the auxiliary cylinder 21. A detachable cylinder cover is provided on the auxiliary cylinder 21, and a sealing sleeve 26 is rotatably arranged on the cylinder cover and extends into the auxiliary cylinder 21. A plurality of groups of liquid inlet holes 261 are provided on the sealing sleeve 26, and the liquid inlet holes 261 are staggered with the second oil inlet groove 112 on the main cylinder 11, and the angle between adjacent liquid inlet holes 261 and the second oil inlet groove 112 is angularly spaced from each other. The angle is 45°. In the initial state, the liquid inlet hole 261 on the sealing sleeve 26 is connected with the oil inlet groove 112 on the main cylinder 11. After the hydraulic oil is injected into the cylinder body 1 and the piston rod 12 reaches the required position, the sealing sleeve 26 is driven to rotate 45° to move the liquid inlet hole 261 and the oil inlet groove 112 to be misaligned, thereby blocking the end of the main cylinder 11 provided with the oil inlet groove 112, locking the piston rod 12 to limit the position of the piston rod 12. After the piston rod 12 is compressed, the sealing sleeve 26 Under axial pressure, the liquid inlet hole 261 and the oil inlet groove 112 can only be opened and closed by rotation. Therefore, there is no need to apply continuous pressure to the sealing sleeve 26 to block the main cylinder 11 when limiting the position of the piston rod 12; a secondary piston 22 is provided in the secondary cylinder 21, and the sealing sleeve 26 is connected to the secondary piston 22 by a connecting piece 23. The connecting piece 23 is used to drive the sealing sleeve 26 to rotate to close the end of the main cylinder 11 where the oil inlet groove 112 is provided when the secondary piston 22 moves toward the main cylinder 11.

[0038] Furthermore, the connecting member 23 includes a connecting sleeve 231 arranged on the secondary piston 22, the connecting sleeve 231 is cylindrical and its opening faces the cylinder head, and a connecting column 233 rotatably arranged on the secondary cylinder barrel 21, the connecting column 233 passes through the cylinder head and is connected to the sealing sleeve 26, a sealing ring is provided between the connecting column 233 and the cylinder head, the connecting column 233 and the connecting sleeve 231 are slidably connected, and an arc guide groove 234 is provided on the connecting column 233, and a limiting column 232 extending into the arc guide groove 234 is provided in the connecting sleeve 231. After the secondary piston 22 is pushed by the hydraulic oil, it moves toward the connecting column 233, and with the cooperation of the arc guide groove 234 and the limiting column 232, the connecting column 233 is guided to drive the sealing sleeve 26 to rotate, thereby misaligning the liquid inlet hole 261 and the oil inlet groove 112 to seal the end of the main cylinder barrel 11 provided with the oil inlet groove 112, thereby realizing the position locking of the piston rod 12.

[0039] Among them, the depth of the connecting sleeve 231 is L, the horizontal movement distance of the secondary piston 22 in the secondary cylinder 21 is M, and L is less than M, which prevents the secondary cylinder 21 from excessively moving and causing the locking oil outlet 103 and the locking oil inlet 104 to be interconnected, thereby maintaining the stability of locking and unlocking the piston rod 12.

[0040] In addition, the angle between the initial end and the end of the arc guide groove 234 is 45°, which is used to guide the sealing sleeve 26 to rotate 45°, thereby achieving precise matching of the liquid inlet hole 261 and the second oil inlet groove 112. When the secondary piston 22 is away from the connecting column 233, the sealing sleeve 26 and the main cylinder 11 rotate and gradually open the liquid inlet hole 261 and the second oil inlet groove 112, so that during the unlocking process, the pressure in the main cylinder 11 is slowly released to prevent the piston rod 12 from suddenly dropping, which is safer.

[0041] In addition, it also includes a sealing ball 25, which is movably mounted on the connecting column 233, and an elastic member is provided between the sealing ball 25 and the connecting column 233, and the elastic member is used to always press the sealing ball 25 against the inner wall of the cylinder body 1. When the sealing ball 25 rotates with the connecting column 233 and when the piston rod 12 is locked, the sealing ball 25 will press against the rodless chamber oil port 102, automatically close the rodless chamber oil port 102, reduce the pressure on the hydraulic oil pipe, and thereby reduce the problem of oil leakage at the interface caused by long-term pressure on the hydraulic oil pipe.

[0042] Furthermore, the sealing ball 25 is arranged on the connecting column 233 through the guide column and guide sleeve. The diameter of the guide sleeve is larger than the diameter of the guide column, and the sealing ball 25 is rollingly installed on the guide sleeve. A spring is provided on the guide column, and the spring resists the guide sleeve and the connecting column 233. The rolling sealing ball 25 can reduce the friction with the inner wall of the cylinder body 1 during movement, thereby reducing friction loss.

[0043] Working principle: Hydraulic oil is injected into the cylinder body 1 through the rodless chamber oil port 102. At this time, the liquid inlet hole 261 on the sealing sleeve 26 is connected with the oil inlet groove 112 on the main cylinder barrel 11. The hydraulic oil enters the end of the main cylinder barrel 11 provided with the main piston 13. With the continuous addition of hydraulic oil, the main piston 13 and the piston rod 12 are pushed to move, so as to push the object. When it is necessary to lock the piston rod 12, the injection of hydraulic oil into the rodless chamber oil port 102 is stopped first, and the hydraulic oil in the main cylinder barrel 11 is temporarily restricted from flowing back from the rodless chamber oil port 102. At this time, hydraulic oil is injected into the auxiliary cylinder barrel 21 through the locking oil inlet 104, and the hydraulic oil pushes the auxiliary piston 22 toward the connecting column 2 33 moves, at this time, the connecting sleeve 231 is gradually sleeved on the connecting column 233, the limiting column 232 arranged on the connecting sleeve 231 and the arc-shaped guide groove 234 on the outer peripheral surface of the connecting column 233 cooperate to guide the sealing sleeve 26 to rotate. When the secondary piston 22 moves a distance L, the connecting column 233 drives the sealing sleeve 26 to rotate 45°, so that the liquid inlet hole 261 on the sealing sleeve 26 is completely misaligned with the oil inlet groove 112 on the main cylinder 11, and the end of the main cylinder 11 provided with the oil inlet groove 112 is closed, and the hydraulic oil between the main piston 13 and the sealing sleeve 26 cannot overflow. At this time, due to the characteristic that the hydraulic oil cannot be compressed, the position of the piston rod 12 is restricted and locked.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-large tonnage combined type arbitrary position self-locking oil cylinder, comprising a cylinder body (1), wherein a main cylinder barrel (11) is arranged in the cylinder body (1), and a piston rod (12) is slidably mounted in the main cylinder barrel (11), characterized in that: The main cylinder (11) is provided with a first oil inlet groove (111) and a second oil inlet groove (112) at both ends thereof, and further comprises: A locking assembly (2) for limiting the movement of a piston rod (12), the locking assembly (2) comprising a secondary cylinder (21) disposed inside a cylinder body (1) and coaxial with the piston rod (12), and a sealing sleeve (26) rotatably disposed on the secondary cylinder (21) for sealing a second oil inlet groove (112), the secondary cylinder (21) being located inside the cylinder body (1) near one end of the main cylinder (11) where the second oil inlet groove (112) is disposed, and the secondary cylinder (21) is provided with a locking oil outlet (103) and a locking oil inlet (104) extending out of the cylinder body (1), the locking oil outlet (103) and the locking oil inlet (104) being respectively located on two sides of the secondary cylinder (21), a secondary piston (22) being disposed inside the secondary cylinder (21), and the sealing sleeve (26) ) is connected to the auxiliary piston (22) via a connecting piece (23), the connecting piece (23) comprising a connecting sleeve (231) arranged on the auxiliary piston (22) and a connecting column (233) rotatably arranged on the auxiliary cylinder barrel (21), the connecting sleeve (231) being cylindrical and having an opening facing the cylinder head, the connecting column (233) and the connecting sleeve (231) being slidably connected, the connecting column (233) being provided with an arc-shaped guide groove (234), the connecting sleeve (231) being provided with a limiting column (232) extending into the arc-shaped guide groove (234), the connecting piece (23) being used for driving the sealing sleeve (26) to rotate to close one end of the main cylinder barrel (11) provided with the second oil inlet groove (112) when the auxiliary piston (22) moves toward the main cylinder barrel (11).

2. The ultra-large tonnage combined type arbitrary position self-locking cylinder according to claim 1, characterized in that: The cylinder body (1) is provided with a rod chamber oil port (101) and a rodless chamber oil port (102); the rod chamber oil port (101) is located on a side of the main cylinder barrel (11) on which a first oil inlet groove (111) is provided; the rodless chamber oil port (102) is located on a side of the main cylinder barrel (11) on which a second oil inlet groove (112) is provided; a main piston (13) is provided at one end of the piston rod (12) close to the rodless chamber oil port (102); hydraulic oil is injected into the cylinder body (1) through the rodless chamber oil port (102) to drive the main piston (13) to push the piston rod (12) out of the cylinder body (1); hydraulic oil is injected into the cylinder body (1) through the rod chamber oil port (101) to drive the main piston (13) to push the piston rod (12) back into the cylinder body (1).

3. The ultra-large tonnage combined type arbitrary position self-locking cylinder according to claim 1, characterized in that: The depth of the connecting sleeve (231) is L, the distance of horizontal movement of the secondary piston (22) in the secondary cylinder (21) is M, and L is less than M, so as to prevent the secondary cylinder (21) from excessively moving and causing the locking oil outlet (103) and the locking oil inlet (104) to communicate with each other.

4. The ultra-large tonnage combined type arbitrary position self-locking cylinder according to claim 3 is characterized in that: The included angle between the initial end and the final end of the arc-shaped guide groove (234) is 45°.

5. The ultra-large tonnage combined type arbitrary position self-locking cylinder according to claim 1, characterized in that: The sealing sleeve (26) is provided with a plurality of groups of liquid inlet holes (261), and the liquid inlet holes (261) and the second oil inlet groove (112) on the main cylinder (11) are staggered and arranged, and the angle between adjacent liquid inlet holes (261) and the second oil inlet groove (112) is 45°.

6. The ultra-large tonnage combined type arbitrary position self-locking cylinder according to claim 1, characterized in that: It also includes a sealing ball (25), which is movably mounted on the connecting column (233), and an elastic member is provided between the sealing ball (25) and the connecting column (233), and the elastic member is used to always press the sealing ball (25) against the inner wall of the cylinder body (1).

7. The ultra-large tonnage combined type arbitrary position self-locking cylinder according to claim 6, characterized in that: The sealing ball (25) is arranged on the connecting column (233) through the cooperation of a guide column and a guide sleeve, the diameter of the guide sleeve is larger than the diameter of the guide column, and the sealing ball (25) is rollingly mounted on the guide sleeve, a spring is sleeved on the guide column, and the spring presses against the guide sleeve and the connecting column (233).

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