Rotary air cylinder

Abstract

The rotary air cylinder comprises a cylinder barrel, a front cover and a rear cover, the front cover and the rear cover are arranged at the two ends of the cylinder barrel respectively, a piston and a piston rod are arranged in the cylinder barrel, the piston and the piston rod are matched to form a limiting structure, and the limiting structure is used for limiting the rotation angle of the piston rod relative to the cylinder barrel. The limiting structure further limits the axial stroke of the piston moving towards the front cover in the cylinder barrel into a first stroke and a second stroke, the limiting structure comprises a stroke adjusting piece arranged on the piston and / or the piston rod, and the stroke adjusting piece is used for adjusting the length of the first stroke. The length of the first stroke of the piston can be adjusted through the stroke adjusting piece, and then the rotation angle of the piston rod can be adjusted. In the actual production process, air cylinders with different rotation angles can be conveniently produced without changing the spiral angle of the spiral groove of the piston rod, the production cost is saved, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of air cylinder, especially relates to a rotary air cylinder. BACKGROUND

[0002] The air cylinder is a pneumatic actuator that converts the pressure energy of compressed gas into mechanical energy in pneumatic transmission, and the piston rod of the traditional air cylinder can only move in the same direction and cannot rotate. In order to meet the needs of users, rotary air cylinders have appeared in the market, and the piston rod of the rotary air cylinder can not only realize the extension and retraction movement in the axial direction, but also can rotate in the circumferential direction to meet the needs of special working conditions.

[0003] For example, a mechanical double-head rotary air cylinder disclosed in Chinese utility model patent (publication number: CN206360958U) is provided with a transmission shaft in the cylinder body, a spiral groove is arranged in the middle of the transmission shaft, a fixed sleeve is sleeved outside the spiral groove, a steel ball is arranged on the fixed sleeve, the steel ball is located in the spiral groove, a guide seat is fixedly sleeved outside the fixed sleeve, a sliding groove is arranged on the guide seat, a guide pin is arranged on the cylinder body, and the guide pin is clamped in the sliding groove. When the cylinder body is filled with gas pressure, the gas pressure drives the sealing ring seat to move. Since the sliding groove is arranged on the guide seat, the guide seat can only move linearly left and right under the limiting action of the guide pin. At the same time, the guide seat moves, the fixed sleeve moves, the steel ball rolls along the spiral groove, and the transmission shaft rotates.

[0004] However, the rotary angle of the transmission shaft of the mechanical double-head rotary air cylinder disclosed in the above-mentioned prior art is limited by the rotary angle of the spiral groove. This means that if air cylinders with different rotary angles are to be manufactured, different spiral grooves must be machined for the transmission shaft. Moreover, the machining precision of the spiral groove is quite high, which undoubtedly greatly increases the production cost.

[0005] Therefore, it is necessary to improve the prior art. UTILITY MODEL CONTENTS

[0006] The utility model aims at the defects and deficiencies of the prior art, and provides a rotary air cylinder, which can adjust the length of the first stroke of the piston through the stroke adjusting piece, and thus conveniently produce air cylinders with different rotary angles.

[0007] To achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0008] A rotary cylinder comprises a cylinder barrel, a front cover and a rear cover arranged at two ends of the cylinder barrel respectively, a piston and a piston rod arranged in the cylinder barrel, the piston is rotationally matched with the cylinder barrel, the piston rod is movably penetrated through the piston, a helical groove is arranged on the peripheral wall of the piston rod, the helical groove spirally extends along the axial direction of the piston rod, the piston is provided with a guide corresponding to the helical groove, a limiting structure is formed between the piston and the piston rod, the limiting structure is used to limit the rotation angle of the piston rod relative to the cylinder barrel, and the limiting structure also limits the axial stroke of the piston in the cylinder barrel to move towards the front cover as a first stroke and a second stroke; when the piston moves in the first stroke, the guide moves along the helical groove with the piston, so that the piston rod rotates relative to the cylinder barrel; when the piston moves to the action position of the limiting structure, the piston enters the second stroke from the first stroke, at this time the piston drives the piston rod to move synchronously in the axial direction; wherein the limiting structure comprises a stroke adjusting member arranged on the piston and / or the piston rod, and the stroke adjusting member is used to adjust the length of the first stroke.

[0009] Further, the stroke adjusting member comprises a snap spring clamped on the peripheral wall of the piston rod, and an annular groove is arranged on the piston rod for mounting the snap spring.

[0010] Further, the stroke adjusting member further comprises a limiting sleeve arranged at the front end of the piston, when the limiting sleeve moves to abut against the snap spring with the piston, the piston enters the second stroke.

[0011] Further, the limiting sleeve has a limiting portion, and the limiting sleeve is matched with the snap spring through the limiting portion.

[0012] Further, an annular sealing ring and a fixing sleeve for fixing the annular sealing ring are arranged between the piston and the piston rod; a first O-shaped sealing ring is arranged between the fixing sleeve and the piston.

[0013] Further, a limiting ring is arranged at the rear end of the piston rod, and a rear anti-collision pad for limiting cooperation with the limiting ring is embedded in the rear cover.

[0014] Further, a stepped portion is arranged at the middle part of the piston rod, and a front anti-collision pad for limiting cooperation with the stepped portion is embedded in the front cover.

[0015] Further, one end of the helical groove extends to the rear end of the piston rod, and the other end of the helical groove extends to the middle part of the piston rod.

[0016] Further, the guide is a cylindrical pin arranged integrally with the piston.

[0017] Further, a guide rod is arranged in the cylinder barrel, two ends of the guide rod are fixedly connected with the front cover and the rear cover respectively, and the guide rod penetrates through the piston to realize the rotationally matched cooperation between the piston and the cylinder barrel.

[0018] With the above structure, the beneficial effects of the utility model are: the utility model discloses a rotary cylinder, including cylinder, the front cover and the back cover of setting respectively in the both ends of cylinder, the piston and the piston rod are set in the cylinder, the cooperation of piston and piston rod forms the limit structure, the limit structure is used to limit the rotation angle of piston rod relative to cylinder, and the limit structure still limits the axial stroke of piston in the cylinder and runs the axial stroke of the front cover direction as the first stroke and the second stroke, the limit structure includes the stroke adjusting piece of setting on the piston and / or piston rod, and the stroke adjusting piece is used for adjusting the length of the first stroke, and its first stroke length of the piston can be adjusted through the stroke adjusting piece, and then the rotation angle of the piston rod is adjusted, in the actual production process, the spiral angle of the spiral groove of the piston rod does not need to be changed, and the cylinder of different rotation angles can be conveniently produced, and production cost is saved. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the specific embodiment of the utility model, the drawings needed to be used in the specific embodiment description will be briefly introduced, and obviously, the drawings in the following description are some embodiments of the utility model, and other drawings can be obtained according to these drawings without the creative labor for the ordinary skilled in the art.

[0020] Figure 1 It is the overall structure of the utility model sectional view;

[0021] Figure 2 It is the limit sleeve of the utility model; Figure 1 The structure of A of the utility model is enlarged and shows the schematic diagram;

[0022] Figure 3 It is the limit sleeve of the utility model sectional view; Figure 1 The length of limit part is L3);

[0023] Figure 4 It is the limit sleeve of the utility model sectional view; Figure 2 The length of limit part is L4);

[0024] Figure 5 It is the first cylinder of the utility model sectional view;

[0025] Figure 6 It is the second cylinder of the utility model sectional view;

[0026] Figure 7 It is the side view of the piston rod of the utility model; Figure 1 The distance of annular groove and piston rod rear end is L5);

[0027] Figure 8It is the side view of the piston rod of the utility model Figure 2 The distance between the annular groove and the rear end of the piston rod is L6.

[0028] Figure 9 It is the sectional view of the third cylinder of the utility model.

[0029] Figure 10 It is the sectional view of the fourth cylinder of the utility model.

[0030] Figures 1 to 10 The middle serial number is:

[0031] 1, cylinder; 11, front cover; 111, first air hole; 12, rear cover; 121, second air hole; 13, rear anti-collision pad; 14, front anti-collision pad; 15, first chamber; 16, second chamber; 2, piston; 21, guide; 3, piston rod; 31, helical groove; 32, annular groove; 33, limiting ring; 34, step part; 4, limiting structure; 41, clamping spring; 42, limiting sleeve; 421, limiting part; 5, annular sealing ring; 51, fixed sleeve; 52, first O-shaped sealing ring; 53, clamping ring; 6, guide rod; 61, guide sleeve; 62, second O-shaped sealing ring; 7, wear-resistant ring; 8, C-shaped sealing ring. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purpose, features and advantages of the utility model more apparent, obvious and easy to understand, the specific embodiments of the utility model are described in detail below. In the following description, a lot of specific details are set forth in order to fully understand the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0033] In the description of the utility model, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the utility model.

[0034] In addition, if these terms "first", "second" appear, these terms are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can be explicitly or implicitly included at least one of the features. In the description of the present application, if the term "a plurality of" appears, the meaning of the term "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0035] In the present application, unless otherwise specifically defined and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise specifically defined and limited, if there is a similar description of the first feature "on" or "under" the second feature, the meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" of the second feature can be the first feature directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" of the second feature can be the first feature directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0037] It should be noted that if an element is referred to as "fixed to" or "provided to" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for the purpose of illustration and do not indicate the only implementation.

[0038] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0039] Embodiment one

[0040] As Figures 1 to 10As shown, a rotary cylinder comprises a cylinder barrel 1, a front cover 11 and a rear cover 12 arranged at two ends of the cylinder barrel 1 respectively, a piston 2 and a piston rod 3 arranged in the cylinder barrel 1, the piston 2 is rotationally matched with the cylinder barrel 1, the piston rod 3 is movably penetrated through the piston 2, a helical groove 31 is arranged on the peripheral wall of the piston rod 3, the helical groove 31 spirally extends along the axial direction of the piston rod 3, the piston 2 is provided with a guide 21 corresponding to the helical groove 31, a limiting structure 4 is formed between the piston 2 and the piston rod 3, the limiting structure 4 is used to limit the rotation angle of the piston rod 3 relative to the cylinder barrel 1, and the limiting structure 4 also limits the axial stroke of the piston 2 in the cylinder barrel 1 to a first stroke and a second stroke in the direction of the front cover 11; when the piston 2 moves in the first stroke, the guide 21 moves along the helical groove 31 with the piston 2, so that the piston rod 3 rotates relative to the cylinder barrel 1; when the piston 2 moves to the action position of the limiting structure 4, the piston 2 enters the second stroke from the first stroke, at this time the piston 2 drives the piston rod 3 to move synchronously in the axial direction; wherein the limiting structure 4 comprises a stroke adjusting member arranged on the piston 2 and / or the piston rod 3, the stroke adjusting member is used to adjust the length of the first stroke. The stroke adjusting member comprises a snap spring 41 clamped on the peripheral wall of the piston rod 3. The stroke adjusting member further comprises a limiting sleeve 42 arranged at the front end of the piston 2, when the piston 2 drives the limiting sleeve 42 to move to abut against the snap spring 41, the piston 2 enters the second stroke. The limiting sleeve 42 has a limiting part 421, the limiting sleeve 42 abuts against the snap spring 41 through the limiting part 421. The rear end of the piston rod 3 is provided with a limiting ring 33, the rear cover 12 is embedded with a rear anti-collision pad 13 used for limiting cooperation with the limiting ring 33. The middle part of the piston rod 3 is provided with a stepped part 34, the front cover 11 is embedded with a front anti-collision pad 14 used for limiting cooperation with the stepped part 34. One end of the helical groove 31 extends to the rear end of the piston rod 3, the other end of the helical groove 31 extends to the middle part of the piston rod 3. The piston 2 divides the inner cavity of the cylinder barrel 1 into a first chamber 15 and a second chamber 16, the front cover 11 is provided with a first gas hole 111 in communication with the first chamber 15, and the rear cover 12 is provided with a second gas hole 121 in communication with the second chamber 16.

[0041] Based on the above embodiment, the utility model wants to solve is provided a kind of rotary cylinder, including cylinder 1, front cover 11 and rear cover 12 respectively arranged in the both ends of cylinder 1, the piston 2 and piston rod 3 are arranged in the cylinder 1, the cooperation between the piston 2 and piston rod 3 forms limit structure 4, the limit structure 4 is used to limit the rotation angle of piston rod 3 relative to cylinder 1, and the limit structure 4 also limits the axial stroke of piston 2 in cylinder 1 to the direction of front cover 11 as first stroke and second stroke, the limit structure 4 includes the stroke adjusting member arranged on the piston 2 and / or piston rod 3, and the stroke adjusting member is used to adjust the length of the first stroke.It is through stroke adjusting member that the length of the first stroke of piston can be adjusted, and then the rotation angle of piston rod 3 is adjusted.In actual production process, the helix angle of the helical groove 31 of piston rod 3 does not need to be changed, so that the cylinder with different rotation angles can be conveniently produced, and production cost is saved.

[0042] Specifically, in order to facilitate description, the distance between the front end face of the rear cover 12 and the rear end face of the snap spring 41 is defined as L, and L is a fixed value, the first stroke of the piston 2 running in the cylinder 1 to the front cover 11 is defined as L1, and the first stroke L1 is specifically the displacement of the piston 2 running from the state that the rear end face of the piston 2 abuts against the rear cover 12 to the state that the limit sleeve 42 abuts against the snap spring 41, when the piston 2 is in the first stroke L1, the piston rod 3 rotates under the drive of the piston 2; the second stroke of the piston 2 running in the cylinder 1 to the front cover 11 is defined as L2, when the piston 2 is in the second stroke L2, the piston rod 3 moves axially under the drive of the piston 2, that is, the second stroke L2 of the piston 2 is equivalent to the axial stroke of the piston rod 3, specifically the displacement of the piston rod 3 running from the state that the limit ring 33 abuts against the rear anti-collision pad 13 to the state that the stepped portion 34 abuts against the front anti-collision pad 14, and L2 is a fixed value. As shown in Figure 3 and Figure 4 The limit sleeve 42 with different lengths of limit portions 421 is shown in Figure 3 In order to facilitate description, the cylinder using the limit sleeve 42 (the length of the limit portion 421 is L3) shown in Figure 5 is named as the first cylinder, and the first stroke of the piston 2 of the first cylinder is L11, as shown in Figure 4 The cylinder using the limit sleeve 42 (the length of the limit portion 421 is L4) shown in Figure 6 is named as the second cylinder, and the first stroke of the piston 2 of the second cylinder is L21. In order to facilitate description, the length of the piston 2 is defined as L7, and L7 is a fixed value. It can be understood that L3+L7+L11=L4+L7+L21=L, and it can be known from Figures 3 to 6 that L3L4, then L11>L21, and further the rotation angle of the piston rod 3 of the first cylinder is greater than the rotation angle of the piston rod 3 of the second cylinder.

[0043] The cylinder working process: taking the door pump cylinder applied to a bus as an example, when the second gas hole 121 inhales, the piston 2 can only move forward under the action of the guide rod 6, and the gas in the first chamber 15 is discharged from the first gas hole 111, at this time, since the free end of the piston rod 3 is subjected to the load force of the door, the piston rod 3 can only rotate under the cooperation of the guide 21 and the spiral groove 31, when the piston 2 moves to the limit sleeve 42 and abuts against the snap spring 41, the piston 2 enters the second stroke, the piston rod 3 is driven by the piston 2 to move forward against the load force of the door, until the step part 34 of the piston rod 3 abuts against the front anti-collision pad 14, so that the output of the piston rod 3 to the outside is first rotation and then forward extension; when the first gas hole 111 inhales, the gas in the second chamber 16 is discharged from the second gas hole 121, and the piston rod 3 moves backward to the limit ring 33 and abuts against the rear anti-collision pad 13 under the action of the load force of the door, at this time, the piston 2 moves backward under the action of the gas pressure, and the piston rod 3 rotates under the cooperation of the guide 21 and the spiral groove 31, until the piston 2 abuts against the rear cover 12, and the piston rod 3 stops rotating.

[0044] In the embodiment, the guide 21 is a cylindrical pin which is integrally arranged with the piston 2, the cylindrical pin shaft is integrally machined with the piston 2, so that the rigidity of the cylindrical pin is stronger, and the service life of the piston 2 and the cylindrical pin is improved. In other preferred embodiments, the guide 21 can also be a steel ball. In the embodiment, the hardness of the material of the limit sleeve 42 is greater than the hardness of the material of the piston 2, and the limit sleeve 42 is arranged to improve the service life of the piston 2. In the embodiment, the piston rod 3 is provided with two spiral grooves 31 which are symmetrically distributed on the peripheral wall of the piston rod 3, and correspondingly, the piston 2 is provided with two cylindrical pins, so that the driving force of the piston 2 to the piston rod 3 is more uniform, and the movement of the piston rod 3 is more stable.

[0045] As another preferred scheme of the utility model, the piston 2 and the piston rod 3 are provided with an annular sealing ring 5 and a fixing sleeve 51 for fixing the annular sealing ring 5; the fixing sleeve 51 and the piston 2 are provided with a first O-shaped sealing ring 52. The fixing sleeve 51 is limited and matched with the piston 2 through a snap ring 53. In the embodiment, as shown in Figure 1 and Figure 2 The annular sealing ring 5 and the first O-shaped sealing ring 52 are arranged to improve the air tightness between the piston 2 and the piston rod 3. The fixing sleeve 51 makes the installation of the annular sealing ring 5 and the first O-shaped sealing ring 52 more reliable, and avoids the annular sealing ring 5 and the first O-shaped sealing ring 52 from running out of position during movement. The snap ring 53 is arranged to avoid the fixing sleeve 51 from being separated from the rear end of the piston 2.

[0046] In another preferred embodiment of this utility model, a guide rod 6 is provided inside the cylinder 1. The two ends of the guide rod 6 are fixedly connected to the front cover 11 and the rear cover 12, respectively, and the guide rod 6 passes through the piston 2 to achieve an anti-rotation fit between the piston 2 and the cylinder 1. A guide sleeve 61 and a second O-ring seal 62 are provided between the guide rod 6 and the piston 2. A wear-resistant ring 7 and a C-ring seal 8 are provided between the piston 2 and the inner wall of the cylinder 1. In this embodiment, as... Figure 1 and Figure 2 As shown, the piston 2 achieves anti-rotation engagement with the cylinder 1 via guide rods 6. In this embodiment, two guide rods 6 are provided between the front cover 11 and the rear cover 12, and the two guide rods 6 are symmetrically arranged, so that the piston 2 is subjected to a uniform guiding force during movement. The guide sleeve 61 makes the sliding of the piston 2 relative to the guide rods 6 more stable. The second O-ring seal 62 and C-ring seal 8 increase the airtightness between the first chamber 15 and the second chamber 16. The wear-resistant ring 7 reduces the frictional wear of the piston 2, which helps to improve the service life of the piston 2.

[0047] Example 2

[0048] This embodiment provides a rotary cylinder, whose main structure and related principles are the same as those in Embodiment 1. The difference is that the stroke adjustment component includes a retaining spring 41 that is locked onto the circumferential wall of the piston rod 3, and the piston rod 3 is provided with an annular groove 32 for mounting the retaining spring 41.

[0049] In this embodiment, as Figures 7 to 10 As shown, by adjusting the position of the annular groove 32, i.e., adjusting the installation position of the retaining ring 41, the length of the first stroke of the piston 2 can be adjusted, thereby adjusting the rotation angle of the piston rod 3. Specifically, for ease of description, the total length of the piston 2 and the limiting sleeve 42 is defined as L7', and the distance from the rear end of the piston rod 3 to the front end face of the rear cover 12 is defined as L8 (at this time, the limiting ring 33 abuts against the rear anti-collision pad 13); the first stroke of the piston 2 moving in the cylinder 1 towards the front cover 11 is defined as L1. The first stroke L1 is specifically the displacement of the piston 2 from the state where the rear end face of the piston 2 abuts against the rear cover 12 to the state where the limiting sleeve 42 abuts against the retaining ring 41. When the piston 2 is in the first stroke... Within stroke L1, the piston rod 3 rotates under the drive of the piston 2. The second stroke of the piston 2 moving towards the front cover 11 within the cylinder 1 is defined as L2. When the piston 2 is within the second stroke L2, the piston rod 3 moves axially under the drive of the piston 2. That is, the second stroke L2 of the piston 2 is equal to the axial stroke of the piston rod 3, specifically the displacement of the piston rod 3 from the state where the limiting ring 33 abuts against the rear anti-collision pad 13 to the state where the step portion 34 abuts against the front anti-collision pad 14, and L2 is a fixed value. Figure 7 and Figure 8As shown, the piston rod 3 provided with the annular groove 32 at different positions, for the convenience of expression, will be selected as Figure 7 The cylinder of the piston rod 3 (the distance between the annular groove 32 and the rear end of the piston rod 3 is L5) as shown is named as the third cylinder, as Figure 9 As shown, the first stroke of the piston 2 of the third cylinder is L31, which can be understood as L31=L5-L7'-L8; will be selected as Figure 8 The cylinder of the piston rod 3 (the distance between the annular groove 32 and the rear end of the piston rod 3 is L6) as shown is named as the fourth cylinder, as Figure 10 As shown, the first stroke of the piston 2 of the fourth cylinder is L41, which can be understood as L41=L6-L7'-L8. It can be known that Figures 7 to 10 L5>L6, then L31>L41, and further the rotation angle of the piston rod 3 of the third cylinder is greater than that of the fourth cylinder.

[0050] Obviously, the above-mentioned embodiments are only examples for clearly illustrating, but not limit the embodiments. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A rotary cylinder comprising a cylinder barrel (1), a front cover (11) and a rear cover (12) arranged at two ends of the cylinder barrel (1) respectively, a piston (2) and a piston rod (3) arranged in the cylinder barrel (1), the piston (2) being rotationally fitted with the cylinder barrel (1), the piston rod (3) being movably penetrated through the piston (2), a helical groove (31) being arranged on the peripheral wall of the piston rod (3), the helical groove (31) spirally extending along the axial direction of the piston rod (3), the piston (2) being provided with a guide (21) corresponding to the helical groove (31), characterized in that: a limiting structure (4) is formed between the piston (2) and the piston rod (3), the limiting structure (4) is used to limit the rotation angle of the piston rod (3) relative to the cylinder barrel (1), and the limiting structure (4) also limits the axial stroke of the piston (2) in the cylinder barrel (1) in the direction of the front cover (11) as a first stroke and a second stroke; when the piston (2) moves in the first stroke, the guide (21) moves along the helical groove (31) following the piston (2), so that the piston rod (3) rotates relative to the cylinder barrel (1); when the piston (2) moves to the action position of the limiting structure (4), the piston (2) enters the second stroke from the first stroke, at this time the piston (2) drives the piston rod (3) to move synchronously in the axial direction; wherein the limiting structure (4) comprises a stroke adjusting member arranged on the piston (2) and / or the piston rod (3), the stroke adjusting member is used to adjust the length of the first stroke. The stroke adjusting member comprises a snap spring (41) clamped on the peripheral wall of the piston rod (3), and the piston rod (3) is provided with an annular groove (32) for mounting the snap spring (41). The stroke adjusting member further comprises a limiting sleeve (42) arranged at the front end of the piston (2), when the piston (2) drives the limiting sleeve (42) to move to abut against the snap spring (41), the piston (2) enters the second stroke. The limiting sleeve (42) has a limiting portion (421), and the limiting sleeve (42) abuts against the snap spring (41) through the limiting portion (421). An annular sealing ring (5) and a fixing sleeve (51) for fixing the annular sealing ring (5) are arranged between the piston (2) and the piston rod (3); a first O-shaped sealing ring (52) is arranged between the fixing sleeve (51) and the piston (2).

2. A rotary cylinder as claimed in claim 1, characterized in that: A limiting ring (33) is arranged at the rear end of the piston rod (3), and the rear cover (12) is embedded with a rear anti-collision pad (13) for limiting cooperation with the limiting ring (33).

3. A rotary cylinder as claimed in claim 2, characterized in that: A stepped portion (34) is arranged at the middle portion of the piston rod (3), and the front cover (11) is embedded with a front anti-collision pad (14) for limiting cooperation with the stepped portion (34).

4. A rotary cylinder as claimed in claim 3, characterized in that: One end of the helical groove (31) extends to the rear end of the piston rod (3), and the other end of the helical groove (31) extends to the middle portion of the piston rod (3).

5. A rotary cylinder as claimed in claim 1, characterized in that: The guide (21) is a cylindrical pin arranged integrally with the piston (2).

6. A rotary cylinder as claimed in claim 1, characterized in that: ​ 7. A rotary cylinder as claimed in claim 1, characterized in that: ​ 8. A rotary cylinder as claimed in claim 1, characterized in that: ​ 9. A rotary cylinder as claimed in claim 1, characterized in that: ​ 10. A rotary cylinder as claimed in claim 1, characterized in that: The cylinder (1) is provided with a guide rod (6), two ends of the guide rod (6) are fixedly connected with a front cover (11) and a rear cover (12) respectively, and the guide rod (6) penetrates the piston (2), so that the piston (2) is rotationally connected with the cylinder (1).

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