A frictionless cylinder with adjustable air film gap

Abstract

The present invention discloses a frictionless cylinder with an adjustable air film gap, which relates to the field of linear drive mechanisms, and comprises a cylinder barrel and a first end cover and a second end cover at both ends of the cylinder barrel; the cylinder barrel has a working chamber, the working chamber is provided with a piston assembly, the first end cover is processed with a first air hole connected to the working chamber, the second end cover comprises a plurality of end cover blocks spliced ​​to each other, and a second distance adjustment assembly is provided between adjacent end cover blocks; at least one of the end cover blocks is processed with a second air film surface on one side close to the through gap, and by ventilating the second air film surface, an air film support can be formed for the piston and / or the piston rod portion passing through the through gap. The present invention can achieve the purpose of convenient adjustment of the supporting air film by making a relatively easy-to-produce split design for the end cover that partially contacts the piston assembly, and the gap between each monomer part constituting the end cover can be fine-tuned.

Description

Technical Field

[0001] The invention relates to the field of linear drive mechanisms, and in particular to a frictionless cylinder with adjustable air film gap. Background Art

[0002] Ordinary cylinders generally use mechanical seals. There is friction between the inner wall of the cylinder and the piston, and between the rod end cover and the piston rod. In order to reduce the friction, the common methods are to add lubricating oil to the actual contact position and use low-friction materials. The above methods only reduce the friction resistance to the piston movement, but the friction is still not effectively eliminated.

[0003] In the prior art, there are diaphragm-type low-friction cylinders and frictionless cylinders using air bearings and gap seals. The former uses a rubber diaphragm as an actuator, has no leakage during operation, and has low friction resistance. However, due to the limitation of the diaphragm, the working stroke and life of the cylinder are limited. The latter makes the friction of the piston during movement almost negligible. This new type of cylinder has breakthroughs in applications of low-speed and high-speed and high-frequency motion, but it is difficult to process and its air film gap cannot be adjusted, so its usage scenarios are easily limited. Summary of the invention

[0004] The object of the present invention is to provide a frictionless cylinder with an adjustable air film gap. The frictionless cylinder can be designed in a split manner by partially designing the end cover that contacts the piston assembly. The gap between each single part that constitutes the end cover can be fine-tuned, thereby achieving the purpose of convenient adjustment of the supporting air film under the premise of relatively easy processing.

[0005] An embodiment of the present invention is implemented as follows: a frictionless cylinder with an adjustable air film gap comprises a cylinder barrel and a first end cover and a second end cover respectively arranged at both ends of the cylinder barrel; a working chamber is provided in the cylinder barrel, a piston assembly consisting of a piston and a piston rod is provided in the working chamber, the first end cover is processed with a first air hole connected to the working chamber, the second end cover comprises a plurality of end cover blocks spliced ​​to each other, a through gap is formed between the plurality of end cover blocks spliced ​​to each other for the piston and / or the piston rod to pass through, each end cover block is connected to the cylinder barrel, and a second distance adjustment assembly is provided between adjacent end cover blocks to achieve adjustment of the caliber of the through gap; a second air film surface is processed on a side of at least one end cover block close to the through gap, and an air film support can be formed for the piston and / or piston rod part passing through the through gap by ventilating the second air film surface.

[0006] Furthermore, the second distance adjustment component is a fine-tuning bolt, and the distance between adjacent end cover blocks can be adjusted by rotating the fine-tuning bolt.

[0007] Furthermore, the number of the end cover blocks is four, and a through gap with a rectangular end surface is formed between the four end cover blocks.

[0008] Furthermore, each end cover block is provided with a second air film surface, and each end cover block is processed with a second air inlet and a second air outlet communicating with its second air film surface; at least one end cover block is processed with a second air hole communicating with the working chamber.

[0009] Furthermore, the cylinder barrel includes a plurality of side panels spliced ​​to each other, and a working chamber is formed between the plurality of side panels spliced ​​to each other. The number of side panels is the same as the number of end cover blocks, and each side panel is connected to a corresponding single end cover block, and the first end cover is connected to at least one side panel. A first distance adjustment assembly is arranged between adjacent side panels to adjust the caliber of the working chamber. A first air film surface is processed on a side of at least one side panel close to the working chamber, and an air film support can be formed for the piston assembly by ventilating the first air film surface.

[0010] Furthermore, the first distance adjustment component is a fine-tuning bolt, and the distance between adjacent side panels can be adjusted by rotating the fine-tuning bolt.

[0011] Furthermore, a first air film surface is arranged on each side plate, and a first air inlet hole and a first air outlet hole communicating with the first air film surface are processed on each side plate.

[0012] Furthermore, the piston includes a hollow expansion section and a hollow reduction section, the expansion section is located in the working chamber, and the reduction section is located in the through gap; an adapter plate is provided in the expansion section, and the piston rod can be movably provided in the reduction section, one end of the piston rod passes through the reduction section, and a floating joint is connected between the other end and the adapter plate.

[0013] Furthermore, an exhaust groove is processed on the outer wall of the diameter expansion section, and the exhaust groove is arranged along the circumferential direction of the diameter expansion section.

[0014] Furthermore, there are multiple exhaust grooves, and the edges of the expanded diameter sections between adjacent exhaust grooves are processed with chamfers.

[0015] The beneficial effects of the embodiments of the present invention are:

[0016] The frictionless cylinder provided in the embodiment of the present invention can form an air film support for the part of the piston assembly passing through by adopting an air bearing as the second end cover at one end of the cylinder barrel and the piston assembly. The second end cover adopts a split design that is relatively easy to produce and process, and can achieve micro-adjustment between adjacent single end cover blocks, thereby achieving adjustment of the caliber size of the overall through gap, and finally achieving adjustment of the gap between the cylinder barrel and the piston assembly, that is, the thickness of the air film, so as to achieve different air film rigid support effects, and finally expand its range of usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic cross-sectional structural diagram of a frictionless cylinder provided in an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the structure of an end cover block provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the structure of a second end cover provided in an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the structure of a side panel provided by an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the structure of a cylinder barrel provided in an embodiment of the present invention;

[0023] Figure 6 A schematic structural diagram of a first end cover provided in an embodiment of the present invention;

[0024] Figure 7 A schematic diagram of the structure of a piston provided in an embodiment of the present invention;

[0025] Figure 8 A schematic diagram of the gas path of the second end cover provided in an embodiment of the present invention;

[0026] Fig. 9 A schematic diagram of the gas path of a cylinder provided in an embodiment of the present invention;

[0027] Fig.10 A schematic diagram of a gas path for gas leakage in a frictionless cylinder provided in an embodiment of the present invention.

[0028] Icon: 1-cylinder barrel; 2-first end cover; 3-second end cover; 4-piston; 5-adapter plate; 6-floating joint; 7-piston rod; 11-working chamber; 12-side plate; 13-first air film surface; 14-first air inlet; 15-first air outlet; 21-first air hole; 31-end cover block; 32-through gap; 33-second air film surface; 34-second air inlet; 35-second air outlet; 36-second air hole; 41-expanding section; 42-reducing section; 43-exhaust groove; 44-cut corner; 131-throttle hole; 132-exhaust groove; 331-throttle hole; 332-exhaust groove. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0033] In addition, the terms "parallel", "vertical", etc. do not mean that the components are absolutely parallel or vertical, but can be slightly tilted. For example, "parallel" only means that its direction is more parallel to "vertical", which does not mean that the structure must be completely parallel, but can be slightly tilted.

[0034] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Example

[0036] See also Figure 1 to Figure 3The frictionless cylinder with adjustable air film gap provided in this embodiment includes a cylinder barrel 1 and a first end cover 2 and a second end cover 3 respectively arranged at both ends of the cylinder barrel 1. The cylinder barrel 1 has a working chamber 11, which means that the inner chamber of the cylinder barrel 1 as a whole can be the working chamber 11, or the inner chamber part of the cylinder barrel 1 serves as the working chamber 11. The working chamber 11 is provided with a piston assembly consisting of a piston 4 and a piston rod 7, which means that the working chamber 11 is used to install or assemble the piston assembly to achieve the purpose of forming the cylinder body. It should be noted that the piston assembly can be in a form in which both the piston 4 and the piston rod 7 can extend out of the working chamber 11, or it can be in a form in which one of them, such as the piston rod, extends out of the working chamber 11.

[0037] The first end cover 2 is processed with a first air hole 21 connected to the working chamber 11. The first air hole 21 can be used for air inlet and outlet, so that gas can be input through the first air hole 21 to drive the piston 4 and / or piston rod 7 of the piston assembly to move. This generally refers to driving the piston 4 to move, relying on the piston 4 to drive the piston rod 7 to move, but other forms of only driving the piston rod 7 to move are not excluded. The piston assembly moves toward the second end cover 3 to realize traditional piston movement, but in order to achieve the purpose of air film support between the piston assembly and the second end cover 3, and the purpose of adjustable air film gap, the second end cover 3 includes a plurality of end cover blocks 31 spliced ​​to each other, and a through gap 32 is formed between the plurality of end cover blocks 31 spliced ​​to each other for the piston 4 and / or the piston rod 7 to pass through, which means that the through gap 32 can pass through at least one of the piston 4 and the piston rod 7. The purpose of this design is to adapt to the movement of only the piston 4 or the piston rod 7 in the cylinder and the movement of the piston 4 and the piston rod 7. It can be seen that the invention point according to this technical solution can be applicable to different types of cylinder forms. Within the spirit of the purpose and principle of the invention point, all equivalent substitutions without creative labor should fall within the protection scope of the corresponding invention point of this application.

[0038] The second end cover 3 formed by splicing multiple end cover blocks 31 is a cylindrical structure as a whole, and its inner hole, that is, the through gap 32, is interconnected with the working chamber 11, which can be coaxially connected or eccentrically connected, and it only needs to meet the requirement that the piston assembly can move from the working chamber 11 to the through gap 32. Among them, each end cover block 31 is connected to the cylinder barrel 1, and the connection method can be a detachable connection such as screw connection, clamping connection, riveting connection, buckle connection, etc., and the connection is sealed or airtight. A second distance adjustment component is arranged between adjacent end cover blocks 31 to adjust the caliber size of the through gap 32, which means that the adjacent end cover blocks 31 are not only connected to each other through the second distance adjustment component, but also the second distance adjustment component itself can adjust the length or adjust the spacing between adjacent end cover blocks 31 by changing the interval between itself and the corresponding end cover block 31, so that the cross-sectional area of ​​the through gap 32 increases or decreases, and the purpose of adjusting its caliber size is achieved. It should be noted that the second distance adjustment component can be an electrically driven, hydraulic or pneumatic telescopic rod, or it can be a conventional high-precision fastener, such as bolts, countersunk screws, studs, connecting pins, etc. Fine-tuning bolts (bolts with high processing precision that can achieve micron-level rotation adjustment) are used here to achieve the purpose of stable connection and easy adjustment.

[0039] At least one end cover block 31 is processed with a second air film surface 33 on one side close to the through gap 32. By ventilating or inflating the second air film surface 33, an air film support can be formed for the piston 4 and / or piston rod 7 part that passes through the through gap 32, that is, it is the piston 4 or the piston rod 7 that passes through, and only the one that passes through is supported by the air film. If the two pass through simultaneously, the one or both that can directly contact the air film are supported by the air film, so that the entire second end cover 3 can achieve the purpose of an air bearing. Through the above design, especially the split design of the second end cover 3, compared with the traditional air bearing frictionless cylinder, the air film gap of the second end cover 3 is adjustable, and the enclosed cylindrical structure of the entire second end cover 3 not only reduces the processing accuracy of the second end cover 3 itself (because high air tightness requires low high processing accuracy), but also the air film gap can be adjusted with the change of the use scenario, avoiding the problem of the limitation of the use of the traditional frictionless cylinder.

[0040] As for the cylindrical structure of the second end cover 3, it can be a circular cylinder, a square cylinder or other polygonal columnar cylinder. In order to conform to the current usage concept, it can be constructed as a square cylinder structure, that is, in the present embodiment, the number of the end cover blocks 31 is four, and a through gap 32 with a rectangular end face is formed between the four end cover blocks 31. Of course, in order to meet the needs of other scenarios, in other embodiments, the number of the end cover blocks 31 may also change accordingly, and even more complex combined structures may be achieved by combining more blocks. It should be noted that no matter how many end cover blocks 31 there are, for the state after splicing, at least one end cover block 31 is close to the through gap 32 and the side wall portion connected to the through gap 32 is processed with the second air film surface 33, thereby achieving the role of air film support.

[0041] In order to further enhance the effect of air film support, a second air film surface 33 is provided on each end cover block 31, so that all second air film surfaces 33 can circle around the through gap 32, and provide air film support for the corresponding piston assembly on all sides, so as to achieve a more sufficient support effect and realize the purpose of relative motion closer to zero friction. Each end cover block 31 is processed with a second air inlet 34 and a second air outlet 35 in communication with its second air film surface 33. Of course, the form of the second air inlet 34 and the second air outlet 35 here is not limited, and can be in the form of a through hole, a through groove, or a through cavity. The number includes but is not limited to one or a group, all of which can achieve the purpose of smooth air intake and air outlet. In addition, a throttling component can be added in the process from air intake to air outlet to achieve the purpose of controlling the output of the airflow. Through the above design, the cylindrical structure of the entire cylinder barrel 1 enclosed not only reduces the assembly and processing accuracy of the cylinder barrel 1 itself, but also the air film gap can be adjusted with the change of the use scene, which also avoids the problem of the limitation of the use of traditional frictionless cylinders.

[0042] In this embodiment, the second air film surface 33 is in the form of a flat slit, which can form a good flat air film support for the piston assembly. Specifically, a plurality of throttle holes 331 are arranged on the side of the end cover block 31 close to the through gap 32. The plurality of throttle holes 331 are surrounded by an exhaust groove 332 processed to the side wall on the same side. The exhaust groove 332 is sunken for a certain distance to form the second air film surface 33. At least one end of the exhaust groove 332 passes through the side wall of the end cover block 31 to form the second air outlet 35, or the exhaust groove 332 itself or part of it can form the second air outlet 35, so as to achieve the purpose of exhausting gas through the exhaust groove 332. The second air inlet 34 is arranged on the side of the end cover block 31 away from the through gap 32. The second air inlet 34 is interconnected with all the throttle holes 331. Of course, it can be a form in which one second air inlet 34 corresponds to multiple throttle holes 331, which are connected through a transfer cavity in the middle, or it can be a form in which multiple second air inlet holes 34 correspond to each throttle hole 331 separately. The corresponding gas flow diagram is as follows Figure 8 As shown, the air enters the second air film surface 33 from the second air inlet hole 34 through the throttle hole 331 to form an air film support, and is finally discharged from the exhaust groove 332 .

[0043] Considering that the movement of the piston 4 in the cylinder 1 will also generate a certain friction force, in order to achieve sufficient air film support for the piston 4 and make the movement of the piston assembly closer to zero friction or frictionless, please refer to Figure 4 and Figure 5 , the cylinder barrel 1 includes a plurality of side panels 12 that are spliced ​​to each other, and a working chamber 11 is formed between the plurality of side panels 12 that are spliced ​​to each other. The cylinder barrel 1 formed by the plurality of side panels 12 is a barrel-type structure. The form of this barrel-type structure may be the same as or different from the barrel-type structure of the second end cover 3, as long as the working chamber 11 and the through gap 32 are connected to each other and the connection is sealed. In this embodiment, the number of the side panels 12 is the same as the number of the end cover blocks 31, that is, there are four of them, and each side panel 12 is connected to the corresponding single end cover block 31. The connection methods include but are not limited to detachable connections such as screwing, clamping, riveting, and snapping. The connection is sealed to ensure air tightness. The first end cover 2 is connected to at least one side panel 12 to achieve the purpose of enabling the first air hole 21 to directly connect to the working chamber 11. Please refer to Figure 6 The first end cover 2 is detachably connected to the corresponding port of the cylinder barrel 1 of the cylindrical structure. The detachable connection is as described above and is not limited to a specific form. The first end cover 2 is connected to one end of all the side panels 12 on all sides, and the middle part is raised to form a step to achieve positioning, and the first air hole 21 is located in the middle part.

[0044] Similarly, the cylinder barrel 1 is designed in the form of an air bearing, which can provide frictionless air film support for the piston 4 in accordance with the use requirements. At least one side plate 12 is processed with a first air film surface 13 on the side close to the working chamber 11. By ventilating the first air film surface 13, an air film support can be formed for the piston assembly, especially the piston 4 part (if there is a part directly contacting the piston rod, the piston rod can also be supported by air film). Similarly, in order to further enhance the effect of air film support, a first air film surface 13 is provided on each side plate 12, so that all first air film surfaces 13 can circle around the working chamber 11 and provide air film support for the piston 4 part in all directions, so as to achieve a more sufficient support effect. Each end side plate 12 is processed with a first air inlet 14 and a first air outlet 15 that are in communication with its first air film surface 13. Of course, the form of the first air inlet 14 and the first air outlet 15 here is not limited, and can be in the form of a through hole, a through groove, or a through cavity, and the number thereof includes but is not limited to one or a group.

[0045] In this embodiment, the first air film surface 13 is in the form of a flat slit, which can form a good flat air film support for the piston 4. Specifically, a plurality of throttle holes 131 are arranged on the side of the side plate 12 close to the working chamber 11. The plurality of throttle holes 131 are surrounded by an exhaust groove 132 processed to the side wall on the same side. The exhaust groove 132 is sunken for a certain distance to form the first air film surface 13. The first air outlet hole 15 is located on the side wall of the side plate 12 away from the working chamber 11, and the first air outlet hole 15 is connected to the groove surface of the exhaust groove 132. The first air inlet hole 14 is arranged on the side of the side plate 12 away from the working chamber 11. The first air inlet hole 14 is connected to all the throttle holes 131. Of course, it can be a form in which one first air inlet hole 14 corresponds to multiple throttle holes 131, which are connected through a transfer cavity in the middle, or it can be a form in which multiple first air inlet holes 14 correspond to each throttle hole 131 individually.

[0046] Similarly, in order to achieve an adjustable air film gap between the side plate 12 and the piston 4, a first distance adjustment component is provided between adjacent side plates 12 to achieve adjustment of the caliber of the working chamber 11, which means that the adjacent side plates 12 are not only connected to each other through the first distance adjustment component, but the first distance adjustment component itself can achieve length adjustment or adjust the spacing between adjacent side plates 12 by changing the interval between itself and the corresponding side plate 12, so that the cross-sectional area of ​​the working chamber 11 increases or decreases, thereby achieving the purpose of adjusting the caliber. In this embodiment, the first distance adjustment component and the second distance adjustment component are of the same form, that is, a fine-tuning bolt is used, and the spacing between adjacent side plates 12 can be adjusted by rotating the fine-tuning bolt. It should be noted that the first distance adjustment component and the second distance adjustment component can be operated synchronously or separately, and it is only necessary to remove the connection between the side plate 12 and the corresponding end cover block 31. Please refer to Fig. 9 The gas passes through the first air inlet 14 and then through the throttle hole 131 into the first air film surface 13 for air film support, and then is discharged from the first air outlet 15 through the exhaust groove 132.

[0047] See also Figure 7In order to realize the purpose of the cylinder provided in this embodiment as a double-acting cylinder, at least one end cover block 31 is processed with a second air hole 36 connected to the working chamber 11, and the first air hole 21 and the second air hole 36 respectively inflate the two ends of the piston 4, so as to realize the purpose of the bidirectional sliding action of the piston 4. In this embodiment, the piston 4 includes a hollow enlarged diameter section 41 and a hollow reduced diameter section 42. The hollow here refers to the form of a through hole or a through groove in the middle. The enlarged diameter section 41 and the reduced diameter section 42 can be in the form of a coaxial connection or an eccentric shaft connection. Generally speaking, a coaxial connection is adopted. The enlarged diameter section 41 can be axially slidable in the working chamber 11, and there is a gap between the two to form a supporting air film; the reduced diameter section 42 can be axially movable in the through gap 32, and has a certain micron-level swing amplitude range, and there is a gap between the two to form a supporting air film. The above design of the piston 4 can not only conveniently or directly blow air to the step portion between the expanded diameter section 41 and the reduced diameter section 42 to better achieve smooth movement of the double-acting cylinder, but also the stepped shaft piston 4 can improve the radial load-bearing capacity and reduce the assembly coaxiality requirements.

[0048] An adapter plate 5 is fixed in the expanded diameter section 41, and the piston rod 7 is slidably arranged in the reduced diameter section 42, with a gap between the two to reduce friction; one end of the piston rod 7 passes through the reduced diameter section 42, and a floating joint 6 is connected between the other end and the adapter plate 5. By setting the floating joint 6 between the piston rod 7 and the piston 4, the output error caused by the radial load can be reduced, and the stability of the movement of the piston rod 7 can be improved. Since the diameter of the expanded diameter section 41 is larger than the diameter of the reduced diameter section 42, its air film support function is more critical. In order to make the air film support between the side plate 12 and the expanded diameter section 41 more stable, an exhaust groove 43 is processed on the outer wall of the expanded diameter section 41. The groove direction of the exhaust groove 43 is arranged along the circumference of the expanded diameter section 41. The exhaust groove 43 can be an annular groove or a semi-annular groove. Here, an annular groove is used, which can form a stable support with the air film around. Specifically, there are multiple exhaust grooves 43, and the arrangement range of all exhaust grooves 43 is within the range of air film formation to achieve the purpose of effective air film support. The edges of the expanded diameter section 41 between the adjacent exhaust grooves 43 are processed with a cut corner 45, which means that the expanded diameter section 41 is a regular polygonal prism (hollow), especially a regular quadrangular prism (hollow). The cut corner 45 processed at the edges can support the gas at the edges and flow between the adjacent exhaust grooves 43. The formed air film can act on the key position. Under the premise of low processing cost, the air film support effect is better through the clever limited design. Please refer to Fig.10The gas leakage flow direction of the entire frictionless cylinder, the first air hole 21 and the second air hole 36 can both serve as the air inlet end of the working chamber 11, and after entering the exhaust groove 43, the first air film surface 13 between the cut corners 45 forms an air film support, and finally is discharged from the first air outlet 15.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and the present invention omits the description of known components and processing technologies and processes to avoid unnecessary limitations on the present invention.

Claims

1. A frictionless cylinder with adjustable air film gap, characterized in that: It comprises a cylinder barrel and a first end cover and a second end cover respectively arranged at two ends of the cylinder barrel; The cylinder barrel has a working chamber, and a piston assembly consisting of a piston and a piston rod is arranged in the working chamber. The first end cover is processed with a first air hole connected to the working chamber, and the second end cover includes a plurality of end cover blocks spliced ​​to each other, and a through gap is formed between the plurality of end cover blocks spliced ​​to each other for the piston and / or the piston rod to pass through, each of the end cover blocks is connected to the cylinder barrel, and a second distance adjustment assembly is arranged between adjacent end cover blocks to adjust the caliber of the through gap; The cylinder barrel comprises a plurality of mutually spliced ​​side plates, the working chamber is formed between the plurality of mutually spliced ​​side plates, the number of the side plates is the same as the number of the end cover blocks, and each of the side plates is connected to a corresponding single end cover block, and the first end cover is connected to at least one of the side plates; a first distance adjustment assembly is provided between adjacent side plates to adjust the caliber of the working chamber; A first air film surface is processed on a side of at least one of the side plates close to the working chamber, and air film support can be formed for the piston assembly by ventilating the first air film surface; The piston comprises a hollow enlarged diameter section and a hollow reduced diameter section, wherein the enlarged diameter section is located in the working chamber and the reduced diameter section is located in the through gap; an adapter plate is arranged in the enlarged diameter section, and the piston rod is movably arranged in the reduced diameter section, one end of the piston rod passes through the reduced diameter section, and a floating joint is connected between the other end and the adapter plate; A second air film surface is processed on one side of at least one of the end cover blocks close to the through gap, and air is ventilated in the second air film surface to form an air film support for the piston and / or the piston rod portion passing through the through gap; The second air film surface is arranged on each of the end cover blocks, and a second air inlet and a second air outlet communicating with the second air film surface are processed on each of the end cover blocks; a second air hole communicating with the working chamber is processed on at least one of the end cover blocks.

2. The frictionless cylinder with adjustable air film gap according to claim 1, characterized in that: The second distance adjustment component is a fine-tuning bolt, and the distance between adjacent end cover blocks can be adjusted by rotating the fine-tuning bolt.

3. The frictionless cylinder with adjustable air film gap according to claim 2, characterized in that: The number of the end cover blocks is four, and the through gap with a rectangular end surface is formed between the four end cover blocks.

4. The frictionless cylinder with adjustable air film gap according to claim 1, characterized in that: The first distance adjustment component is a fine-tuning bolt, and the distance between adjacent side panels can be adjusted by rotating the fine-tuning bolt.

5. The frictionless cylinder with adjustable air film gap according to claim 1, characterized in that: The first air film surface is arranged on each of the side panels, and a first air inlet and a first air outlet communicated with the first air film surface are processed on each of the side panels.

6. The frictionless cylinder with adjustable air film gap according to claim 1, characterized in that: An exhaust groove is processed on the outer wall of the diameter expansion section, and the exhaust groove is arranged along the circumferential direction of the diameter expansion section.

7. The frictionless cylinder with adjustable air film gap according to claim 6, characterized in that: There are multiple exhaust grooves, and the edges of the expanded diameter sections between adjacent exhaust grooves are processed with chamfers.

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