Hydraulic cylinder

Abstract

The present invention relates to a hydraulic cylinder, belonging to the technical field of hydraulic machinery. The present invention consists of a limit retaining ring, a retaining ring support ring and a spiral retaining ring to jointly form the limit structure of the entire cylinder head; the piston rod seal does not need to be designed with a seal groove and can be directly installed at the position between the spiral retaining ring and the guide ring. In the preferred embodiment, the piston rod seal, the seal retaining ring, the guide ring, the stop screw, the cylinder head and the dust ring jointly form the sealing and dust-proof structure of the entire cylinder head. The present invention solves the problem that under working conditions such as a relatively large piston rod diameter, a relatively thin cylinder barrel thickness, and a relatively small gap between the cylinder barrel and the piston rod, it is impossible to design a seal groove in the cylinder head structure, thereby making it impossible to limit and seal the inner cavity of the hydraulic cylinder. The structure of the present invention is simple, the installation and disassembly are convenient, and the performance of the hydraulic cylinder is stable and reliable.

Description

Technical Field

[0001] The present invention relates to a hydraulic cylinder, belonging to the technical field of hydraulic machinery. Background Art

[0002] A hydraulic cylinder is an important actuator in construction machinery, and its main structure consists of a cylinder barrel, a piston rod, a cylinder bottom, a cylinder head, etc. The cylinder bottom and the cylinder head are respectively installed at both ends of the cylinder, and together with the cylinder barrel and the piston rod, they form a closed oil chamber. Generally, the cylinder head needs to play the roles of limiting and sealing, and the design stability and reliability are the keys to ensuring the effective and safe operation of the cylinder and the actuator. Conventional cylinder head structural forms mainly include screw connection, threaded connection, key connection, wire connection, etc. These structural forms generally require the sealing element to be assembled on the cylinder head or the cylinder barrel. When the piston rod diameter is relatively large, or the cylinder barrel wall thickness requirement of the cylinder is relatively thin, or the clearance requirement between the cylinder barrel and the piston rod is relatively small, the sealing element groove cannot be designed, such as in a multi-stage cylinder. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: to provide a hydraulic cylinder to solve the problem that the sealing element groove cannot be designed in the above limited situations for the cylinder head, and to ensure reliable limiting of the cylinder head, stable and excellent sealing performance, and convenient installation and disassembly of the cylinder head seal.

[0004] The technical solution adopted by the present invention to solve its technical problems is as follows: a hydraulic cylinder, which includes a cylinder barrel, a piston rod assembly, a limit snap ring, a snap ring support ring, a spiral snap ring, a piston rod seal, a guide ring, and a cylinder head. The cylinder head is fixedly assembled at the end of the cylinder barrel. The limit snap ring, the snap ring support ring, the spiral snap ring, and the guide ring are all arranged inside the cylinder barrel. The outer wall of the guide ring is matched with the inner wall of the cylinder barrel, and the inner wall is matched with the piston rod assembly. The outer end of the guide ring is connected to the cylinder head, and axial limitation is carried out through the cylinder head. The inner wall of the cylinder barrel is provided with a first groove for clamping the limit snap ring and a second groove for clamping the spiral snap ring. The limit snap ring is an annular part spliced by a plurality of arc-shaped unit components. The end face of the limit snap ring facing the cylinder head side is the first end face, and the end face far from the cylinder head side is the second end face. The limit snap ring is installed in the first groove of the cylinder barrel, its first end face is in tight contact with the side wall of the first groove, and the second end face is in tight contact with the limit ring on the piston rod assembly when the oil cylinder extends to the in-place position; the snap ring support ring is arranged on one side of the first end face of the limit snap ring. The outer peripheral surface of the snap ring support ring is matched with the inner wall of the cylinder barrel, and the inner diameter cylindrical surface is matched with the piston rod assembly; the end of the snap ring support ring facing the limit snap ring is the support part, and the outer peripheral surface of the support part is matched with the inner diameter cylindrical surface of the limit snap ring to clamp and fix the limit snap ring in the first groove of the cylinder barrel; one end of the snap ring support ring is connected to the limit snap ring, and the other end is connected to the spiral snap ring. The spiral snap ring is installed in the second groove of the cylinder barrel. The limit structure is jointly composed of the limit snap ring, the snap ring support ring, and the spiral snap ring; the piston rod seal is installed at the position between the spiral snap ring and the guide ring. The inner diameter circumferential surface of the piston rod seal is matched with the piston rod assembly to form a first sealing surface, and the outer diameter circumferential surface is matched with the inner wall of the cylinder barrel to form a second sealing surface.

[0005] Furthermore: The cylinder barrel and the cylinder bottom are assembled by welding, flange connection or integral thread connection.

[0006] Furthermore: The cross-section of the limit snap ring is rectangular; the limit snap ring is composed of three arc-shaped unit components with the same structure. Each arc-shaped unit component is provided with cut surfaces at both ends of its outer arc surface. These cut surfaces make the cross-section width of the arc-shaped unit component show an increasing trend in the direction from the end to the middle.

[0007] Furthermore: The material of the snap ring support ring is polyoxymethylene plastic. The outer peripheral surface of the support part provided on the snap ring support ring is provided with a guide inclined surface or a guide arc surface at the end facing the limit snap ring.

[0008] Furthermore: A seal retaining ring is arranged at the position between the outer end of the piston rod seal and the guide ring. The seal retaining ring and the piston rod seal form a sealing assembly. The material of the seal retaining ring is preferably nylon.

[0009] Furthermore: The inner wall of the cylinder barrel at the end where the cylinder head is assembled is provided with an inlet inclined surface for assembling the piston rod seal.

[0010] Furthermore, an external thread surface is provided at one end of the outer wall of the cylinder barrel where the cylinder head is assembled, and the cylinder head is threadedly connected to the external thread surface of the cylinder barrel; a set screw is provided on the outer peripheral surface of the cylinder head, the axis of the set screw is arranged along the radial direction of the cylinder barrel, and the tail end of the set screw abuts against the outer wall of the cylinder barrel.

[0011] Furthermore, the material of the guide ring is aluminum bronze or tin bronze.

[0012] Furthermore, a dust-proof ring is provided at the outer end position of the inner diameter surface of the cylinder head, and the dust-proof ring cooperates with the piston rod assembly to form a sealing and dust-proof structure.

[0013] Furthermore, the cylinder barrel is a double-acting multi-stage cylinder barrel, or a double-acting single-stage cylinder barrel, or a single-acting multi-stage cylinder barrel, or a single-acting single-stage cylinder barrel.

[0014] The beneficial effects of the present invention are as follows: The limiting structure of the entire cylinder head of the oil cylinder is jointly composed of a limiting snap ring, a snap ring support ring, and a spiral retaining ring; the piston rod seal does not need to be designed with a seal groove and can be directly installed at the position between the spiral retaining ring and the guide ring, so that the inner diameter circumferential surface of the piston rod seal cooperates with the piston rod assembly to form a first sealing surface, and the outer diameter circumferential surface cooperates with the inner wall of the cylinder barrel to form a second sealing surface. In the preferred embodiment, the sealing and dust-proof structure of the entire cylinder head of the oil cylinder is jointly composed of a piston rod seal, a sealing retaining ring, a guide ring, a set screw, a cylinder head, and a dust-proof ring. The present invention solves the problem that in working conditions such as a relatively large piston rod diameter, a relatively thin cylinder barrel thickness, and a relatively small gap between the cylinder barrel and the piston rod, it is impossible to design a seal groove in the cylinder head structure, thereby making it impossible to limit and seal the inner cavity of the oil cylinder. The structure of the present invention is simple, the installation and disassembly are convenient, and the performance of the oil cylinder is stable and reliable. Description of the Drawings

[0015] Figure 1 is a half-sectional view of the overall structure of the present invention applied to a multi-stage double-acting oil cylinder;

[0016] Figure 2 is Figure 1 a partially enlarged schematic view;

[0017] Figure 3 is a front view of the arc unit member constituting the limiting snap ring in the present invention;

[0018] Figure 4 is a side view of the arc unit member constituting the limiting snap ring in the present invention;

[0019] Figure 5 is a front view of the snap ring support ring in the present invention;

[0020] Figure 6 is Figure 5A-A cross-sectional view;

[0021] Figure 7 is a schematic structural view of the cylinder barrel in the present invention;

[0022] Figure 8 is the front view of the guide ring in the present invention;

[0023] Figure 9 is Figure 8 B-B cross-sectional view;

[0024] Figure 10 is the front view of the overall structure of the present invention applied to a single-stage double-acting oil cylinder;

[0025] Figure 11 is the cross-sectional view of the overall structure of the present invention applied to a single-stage double-acting oil cylinder;

[0026] Reference numerals in the figure: cylinder bottom 1, cylinder barrel 2, piston rod assembly 3, limit snap ring 4, snap ring support ring 5, helical retaining ring 6, piston rod seal 7, seal retaining ring 8, guide ring 9, stop screw 10, cylinder head 11, dust ring 12, cutting plane a, first end face b, second end face c, outer peripheral surface d of the support portion, inner diameter cylindrical surface e, outer peripheral surface f of the snap ring support ring, first groove g, second groove h, cylindrical surface i, external thread surface j, lead-in inclined surface k. Detailed implementation manners

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

[0028] As Figures 1 to 11As shown in the figure, the present invention includes a cylinder barrel 2, a piston rod assembly 3, a limit snap ring 4, a snap ring support ring 5, a spiral retaining ring 6, a piston rod seal 7, a guide ring 9, and a cylinder head 11. The cylinder head 11 is fixedly assembled at the end of the cylinder barrel 2. The limit snap ring 4, the snap ring support ring 5, the spiral retaining ring 6, and the guide ring 9 are all arranged inside the cylinder barrel 2. The outer wall of the guide ring 9 is matched with the inner wall of the cylinder barrel 2, and the inner wall is matched with the piston rod assembly 3. The outer end of the guide ring 9 is connected to the cylinder head 11, and axial limitation is carried out through the cylinder head 11. A first groove g for clamping the limit snap ring 4 and a second groove h for clamping the spiral retaining ring 6 are provided on the inner wall of the cylinder barrel 2. The limit snap ring 4 is an annular piece formed by splicing a plurality of arc-shaped unit components. The end face on the side of the limit snap ring 4 facing the cylinder head 11 is the first end face b, and the end face on the side away from the cylinder head 11 is the second end face c. The limit snap ring 4 is installed in the first groove g of the cylinder barrel 2, its first end face b is in tight contact with the side wall of the first groove g, and the second end face c is in tight contact with the limit ring on the piston rod assembly 3 when the oil cylinder extends in place. The snap ring support ring 5 is arranged on one side of the first end face b of the limit snap ring 4. The outer peripheral surface f of the snap ring support ring 5 is matched with the inner wall of the cylinder barrel 2, and the inner diameter cylindrical surface e is matched with the piston rod assembly 3. One end of the snap ring support ring 5 facing the limit snap ring 4 is a support part, and the outer peripheral surface d of the support part is matched with the inner diameter cylindrical surface of the limit snap ring 4, clamping and fixing the limit snap ring 4 in the first groove g of the cylinder barrel 2. One end of the snap ring support ring 5 is connected to the limit snap ring 4, and the other end is connected to the spiral retaining ring 6. The spiral retaining ring 6 is installed in the second groove h of the cylinder barrel 2. The limit structure is jointly composed of the limit snap ring 4, the snap ring support ring 5, and the spiral retaining ring 6. The piston rod seal 7 is installed at the position between the spiral retaining ring 6 and the guide ring 9. The inner diameter circumferential surface of the piston rod seal 7 is matched with the piston rod assembly 3 to form a first sealing surface, and the outer diameter circumferential surface is matched with the inner wall of the cylinder barrel 2 to form a second sealing surface.

[0029] During specific implementation, the cylinder barrel 2 and the cylinder bottom 1 can be assembled by welding, flange connection, or integral thread connection. The limit snap ring 4 is designed as a multi-segment structure and can be conveniently installed into the first groove g of the cylinder barrel 2. After the limit snap ring 4 is installed, it is supported by the snap ring support ring 5, and the spiral retaining ring 6 is used to limit the snap ring support ring 5 to ensure that the snap ring support ring 5 and the limit snap ring 4 are installed in place. The snap ring support ring 5 also plays a role in guiding the piston rod assembly 3. The piston rod seal 7 and the cylinder barrel 2, the piston rod assembly 3 form a sealing cavity. Preferably, a sealing retaining ring 8 is arranged at the position between the outer end of the piston rod seal 7 and the guide ring 9. The sealing assembly is composed of the sealing retaining ring 8 and the piston rod seal 7. The material of the sealing retaining ring 8 is preferably nylon. The sealing retaining ring 8 can provide support for the piston rod seal 7 when under pressure. The material of the guide ring 9 is preferably aluminum bronze or tin bronze. The guide ring 9 guides the extension and retraction of the piston rod assembly 3 to avoid damage to the seal caused by eccentric loading.

[0030] The assembly structure of the cylinder head 11 and the cylinder barrel 2 is preferably as follows: An external thread surface j is provided on the outer wall of the cylinder barrel 2 at the end where the cylinder head 11 is assembled, and the cylinder head 11 is threadedly connected with the external thread surface j of the cylinder barrel 2; A stop screw 10 is provided on the outer peripheral surface of the cylinder head 11, the axis of the stop screw 10 is arranged along the radial direction of the cylinder barrel 2, and the tail end of the stop screw 10 abuts against the outer wall of the cylinder barrel 2. The cylinder head 11 is connected by external threads, which can ensure that the guide ring 9, the sealing retaining ring 8 and the piston rod seal 7 are installed in place to protect the entire sealing mechanism. The designed stop screw 10 can play a role in stopping and preventing loosening, making the overall structure more stable and reliable. Preferably, a dust-proof ring 12 is provided on the inner diameter surface of the cylinder head 11 at its outer end position, and the dust-proof ring 12 cooperates with the piston rod assembly 3 to form a sealing and dust-proof structure. The dust-proof ring 12 designed on the cylinder head 11 can remove dust and impurities outside the piston rod and prevent dust and impurities from entering the oil cylinder and damaging the cylinder block.

[0031] To better achieve the limiting effect, the cross-section of the limiting snap ring 4 is preferably designed as a rectangle. To make the structure simple and reliable and facilitate assembly, the limiting snap ring 4 is composed of three arc-shaped unit components with the same structure. Each arc-shaped unit component is provided with a cutting surface a at both ends of its outer arc surface, and the cutting surface a makes the cross-section width of the arc-shaped unit component (corresponding to the radial direction of the limiting snap ring 4) show an increasing trend in the direction from the end to the middle.

[0032] To facilitate assembly, the material of the snap ring support ring 5 is preferably polyoxymethylene plastic, and a guide inclined surface or a guide arc surface is provided on the outer peripheral surface d of the support part provided on the snap ring support ring 5 at the end facing the limiting snap ring 4.

[0033] To facilitate the assembly of the piston rod seal 7, an introduction inclined surface k is provided on the inner wall of the cylinder barrel 2 at the end where the cylinder head 11 is assembled.

[0034] The cylinder barrel 2 in the present invention can be a double-acting multi-stage cylinder barrel, or a double-acting single-stage cylinder barrel, or a single-acting multi-stage cylinder barrel, or a single-acting single-stage cylinder barrel.

[0035] The following takes the application of the present invention to a multi-stage double-acting oil cylinder as an example to elaborate on the specific implementation manner, and the overall structure diagram is as Figure 1 and Figure 2 shown.

[0036] When assembling the oil cylinder, the cylinder barrel 2 and the cylinder bottom 1 are assembled into one body. Then, the piston rod assembly 3 is inserted into the cylinder barrel 2. Next, the limit snap ring 4 (with a rectangular cross-section) cut into 3 segments is inserted into the first groove g of the cylinder barrel 2. Subsequently, the snap ring support ring 5 is pushed in to ensure that the support lip (the outer peripheral surface d of the support part) of the snap ring support ring 5 is wedged into the inner hole of the limit snap ring 4 to support the limit snap ring 4. Then, the spiral retaining ring 6 is inserted and installed into the second groove h of the cylinder barrel 2, thereby limiting and clamping the snap ring support ring 5 and the limit snap ring 4. The limit snap ring 4, the snap ring support ring 5, and the spiral retaining ring 6 together form the limit structure of the entire oil cylinder.

[0037] Subsequently, the piston rod seal 7 and the seal retaining ring 8 are installed, and then they are pushed in together with the guide ring 9. The cylinder head 11 with the dust seal 12 assembled is screwed on, and the guide ring 9, the seal retaining ring 8, and the piston rod seal 7 are pushed into the cylinder barrel 2 together. After the cylinder head 11 is installed in place, it can ensure that the piston rod seal 7, the seal retaining ring 8, and the guide ring 9 are installed in place. Finally, the cylinder head 11 is braked and locked with the set screw 10 to ensure the safety and reliability of the entire structure. The entire sealing structure and the cylinder barrel 2, the piston rod assembly 3, and the cylinder bottom 1 form a stable and reliable sealed oil cavity, ensuring the safe and effective operation of the oil cylinder. The distance between the piston rod assembly 3 and the limit snap ring 4 limits the working stroke of the entire oil cylinder.

[0038] Figure 3 and Figure 4 The structure schematic diagram of the limit snap ring 4 in the above-mentioned multi-stage double-acting oil cylinder is shown. Before cutting the limit snap ring 4, it should be machined according to its limit dimensions with a rectangular cross-section, and then equally divided into 3 segments. Each segment is as shown in Figure 3 and Figure 4 The two ends of the outer arc surface have a unique chamfer a design, which can ensure that it can be conveniently installed into the first groove g of the cylinder barrel 2. After the limit snap ring 4 is inserted into the first groove g of the cylinder barrel 2, the first end face b is in close contact with the side wall of the first groove g to ensure sufficient contact area with the cylinder barrel 2; the second end face c is in close contact with the limit ring on the piston rod assembly 3 when the oil cylinder extends in place to reduce the impact of the piston rod assembly 3 on the cylinder barrel 2. There are no specific mating requirements between the second end face c and the side wall of the first groove g, as long as it is convenient to install the limit snap ring 4.

[0039] Figure 5 and Figure 6The following is a schematic structural diagram of the snap ring support ring 5 in the above multi-stage double-acting cylinder. The material of the snap ring support ring 5 is generally polyoxymethylene plastic. The outer peripheral surface f of the snap ring support ring 5 is matched with the inner wall of the cylinder barrel 2, and the inner diameter cylindrical surface e is matched with the piston rod assembly 3, guiding the extension and retraction of the piston rod assembly 3, ensuring the sealing performance and service life of the piston rod seal 7 and the sealing ring 8. The end face of the snap ring support ring 5 facing the limit snap ring 4 is provided with an annular protrusion. The outer peripheral surface d of the support part is matched with the inner diameter cylindrical surface of the limit snap ring 4. After installation, it will be stuck into the inner hole of the limit snap ring 4, ensuring that the outer diameter circumferential surface of the limit snap ring 4 is stuck to the bottom surface of the first groove g on the cylinder barrel 2, preventing the limit snap ring 4 from falling out of the first groove g of the cylinder barrel 2 and becoming ineffective.

[0040] Figure 7 The following is a schematic structural diagram of the cylinder barrel 2 in the above multi-stage double-acting cylinder. The main characteristics of the cylinder barrel 2 are that it is processed with a first groove g for installing the limit snap ring 4, a second groove h for installing the spiral retaining ring 6, a cylindrical surface i for forming a sealing surface with the piston rod seal 7 and the sealing ring 8, an external thread surface j for installing the cylinder head 11, and a guiding inclined surface k for facilitating the assembly of the piston rod seal 7. The distance between the first groove g and the second groove h must be matched with the width of the snap ring support ring 5 to ensure that after the spiral retaining ring 6 is installed, the lip surface (the outer peripheral surface d of the support part) of the snap ring support ring 5 can hold the inner hole of the limit snap ring 4. The distance between the second groove h and the small end of the guiding inclined surface k needs to be matched with the piston rod seal 7, the sealing ring 8, and the guide ring 9 to ensure that the seal is installed in place, and the cylindrical surface i on the inner wall of the cylinder barrel 2 must not be damaged to avoid leakage.

[0041] Figure 8 and Figure 9 The following is a schematic structural diagram of the guide ring 9 in the above multi-stage double-acting cylinder. The material of the guide ring 9 should generally be aluminum bronze or tin bronze. It not only plays a guiding role when the piston rod assembly 3 extends and retracts, but also is an essential part for installing the piston rod seal 7 and the sealing ring 8. When the piston rod seal 7 is assembled into the cylinder barrel 2, the friction force between its deformed state and the piston rod assembly 3 and the cylinder barrel 2 will be very large. To ensure the sealing performance of the cylinder, the guide ring 9, the sealing ring 8, and the piston rod seal 7 need to be slowly assembled to the designated position by screwing on the end cover 11.

[0042] The above structure can also be applied to the cylinder such as a double-acting single-stage cylinder (see Figure 10 and Figure 11 ), a single-acting multi-stage cylinder, a single-acting single-stage cylinder and other hydraulic cylinder products, ensuring the safe and reliable use of the cylinder, extending its service life, and ensuring the cleanliness and operational effectiveness of the hydraulic system. The present invention can be widely promoted and applied in the field of hydraulic machinery technology.

Claims

1. A hydraulic cylinder, comprising a cylinder barrel (2), a piston rod assembly (3), a piston rod seal (7), a guide ring (9) and a cylinder head (11). The cylinder head (11) is fixedly assembled at the end of the cylinder barrel (2). The guide ring (9) is arranged inside the cylinder barrel (2). The outer wall of the guide ring (9) is matched with the inner wall of the cylinder barrel (2), and the inner wall is matched with the piston rod assembly (3). The outer end of the guide ring (9) is connected to the cylinder head (11) and is axially limited by the cylinder head (11). It is characterized in that: It also includes a limit snap ring (4), a snap ring support ring (5) and a helical retaining ring (6). The limit snap ring (4), the snap ring support ring (5) and the helical retaining ring (6) are all arranged inside the cylinder barrel (2). The inner wall of the cylinder barrel (2) is provided with a first groove (g) for clamping the limit snap ring (4) and a second groove (h) for clamping the helical retaining ring (6). The limit snap ring (4) is an annular part spliced by a plurality of arc-shaped unit components. The end face of the limit snap ring (4) facing the cylinder head (11) is the first end face (b), and the end face away from the cylinder head (11) is the second end face (c). The limit snap ring (4) is installed in the first groove (g) of the cylinder barrel (2), its first end face (b) is in close contact with the side wall of the first groove (g), and the second end face (c) is in close contact with the limit ring on the piston rod assembly (3) when the oil cylinder extends to the in-place position; The snap ring support ring (5) is arranged on one side of the first end face (b) of the limit snap ring (4). The outer peripheral surface (f) of the snap ring support ring (5) is matched with the inner wall of the cylinder barrel (2), and the inner diameter cylindrical surface (e) is matched with the piston rod assembly (3); One end of the snap ring support ring (5) facing the limit snap ring (4) is a support part, and the outer peripheral surface (d) of the support part is matched with the inner diameter cylindrical surface of the limit snap ring (4), clamping and fixing the limit snap ring (4) in the first groove (g) of the cylinder barrel (2); One end of the snap ring support ring (5) is connected to the limit snap ring (4), and the other end is connected to the helical retaining ring (6). The helical retaining ring (6) is installed in the second groove (h) of the cylinder barrel (2). The limit structure is jointly composed of the limit snap ring (4), the snap ring support ring (5) and the helical retaining ring (6); The piston rod seal (7) is installed at the position between the helical retaining ring (6) and the guide ring (9). The inner diameter circumferential surface of the piston rod seal (7) is matched with the piston rod assembly (3) to form a first sealing surface, and the outer diameter circumferential surface is matched with the inner wall of the cylinder barrel (2) to form a second sealing surface; The material of the snap ring support ring (5) is polyoxymethylene plastic. The outer peripheral surface (d) of the support part provided on the snap ring support ring (5) is provided with a guide inclined surface or a guide arc surface at the end facing the limit snap ring (4); A sealing retaining ring (8) is arranged at the position between the outer end of the piston rod seal (7) and the guide ring (9). The sealing assembly is composed of the sealing retaining ring (8) and the piston rod seal (7); The material of the sealing retaining ring (8) is nylon; The inner wall of the cylinder barrel (2) is provided with a guiding inclined surface (k) at the end where the cylinder head (11) is assembled. The guiding inclined surface (k) is used for assembling the piston rod seal (7); The material of the guide ring (9) is aluminum bronze or tin bronze; The outer wall of the cylinder barrel (2) is provided with an external thread surface (j) at the end where the cylinder head (11) is assembled. The cylinder head (11) is threadedly connected to the external thread surface (j) of the cylinder barrel (2); The outer peripheral surface of the cylinder head (11) is provided with a set screw (10). The axis of the set screw (10) is arranged along the radial direction of the cylinder barrel (2), and the tail end of the set screw (10) abuts against the outer wall of the cylinder barrel (2);The inner diameter surface of the cylinder head (11) is provided with a dust-proof ring (12) at its outer end position, and the dust-proof ring (12) cooperates with the piston rod assembly (3) to form a sealed dust-proof structure.

2. The hydraulic cylinder according to claim 1, characterized in that: The cylinder barrel (2) and the cylinder bottom (1) are assembled by welding, flange connection or integral thread connection.

3. The hydraulic cylinder according to claim 1, wherein: The limiting snap ring (4) has a rectangular cross-section; the limiting snap ring (4) is composed of three arc-shaped unit components with the same structure, and each arc-shaped unit component is provided with a cut surface (a) at both ends of its outer arc surface, and the cut surface (a) makes the cross-sectional width of the arc-shaped unit component show an increasing trend in the direction from the end to the middle.

4. The hydraulic cylinder according to any one of claims 1 to 3, characterized in that: The cylinder barrel (2) is a double-acting multi-stage cylinder barrel, or a double-acting single-stage cylinder barrel, or a single-acting multi-stage cylinder barrel, or a single-acting single-stage cylinder barrel.

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