A piston assembly and hydraulic cylinder incorporating the same

Abstract

The utility model discloses a piston assembly and hydraulic cylinder containing it, including piston rod, piston and bolt, the bolt is with the rear end of piston rod screw thread connection, and the piston has the screw thread cooperation of the outer circumferential surface screw thread of piston rod and is clamped in the spacing portion between piston rod and bolt, the inner diameter of spacing portion is less than the inner diameter of screw thread portion, the utility model discloses the piston assembly adopts double screw thread connection structure, and the relaxation effect is good, and because spacing portion is located the rear end of the screw thread portion of piston, under the premise of not influencing the piston screw thread intensity, the cross -sectional dimension of spacing portion can be made big, thereby increasing extrusion area, and the stress of spacing portion end surface is reduced, and the structure is more reliable and the size arrangement is small for the oil cylinder of big cylinder rod diameter gap.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic cylinder design technology, and in particular to a piston assembly and a hydraulic cylinder comprising the piston assembly. Background Technology

[0002] As the construction machinery industry gradually develops towards higher quality and standards, the requirements for the lifespan, safety performance, and precision control of mechanical equipment are also becoming increasingly stringent.

[0003] Hydraulic cylinders are crucial hydraulic actuators in various fields of machinery, including industrial machinery such as hydraulic cranes and stamping machinery; transportation such as automobile suspension systems, engineering vehicle loaders, and excavators; and aerospace such as aircraft landing gear systems and satellite launch equipment. Whether a hydraulic cylinder has good working performance, safety performance, and lifespan directly affects the various performance characteristics and lifespan of the machinery.

[0004] As a crucial component of hydraulic cylinder design, the piston structure is an indispensable key part of the hydraulic cylinder, enabling the core functions of "pressure generation and motion output." Its design, manufacturing precision, and sealing reliability directly affect the performance and lifespan of the entire hydraulic cylinder.

[0005] Existing piston structures are divided into two types: one-piece and two-piece. The one-piece piston structure connects the piston and piston rod with a threaded connection, and a step at the piston end that limits the piston rod end (e.g., patent number CN202323580461.4). The two-piece piston structure consists of a piston and a bolt or nut, with the piston abutting against the piston rod end and then connected to the piston rod by a nut via a threaded connection. Existing piston structures all use a single thread for locking, resulting in a large thread torque and a tendency to lock up. This is especially true for piston structures with front-end positioning. Due to the limitation of the piston rod diameter, the positioning surface is small, easily creating high pressure at the piston's front-end positioning surface, which can cause piston deformation or cracking, affecting the service life of the hydraulic cylinder.

[0006] Therefore, a piston assembly structure with high connection strength and longer service life needs to be designed. Utility Model Content

[0007] To address the technical problems of existing piston structures, such as excessive thread torque leading to locking and high pressure at the piston's front-end positioning surface causing deformation or cracking, this invention provides a piston assembly and a hydraulic cylinder comprising it to solve these problems.

[0008] This utility model proposes a piston assembly, including a piston rod, a piston, and a bolt. The bolt is threadedly connected to the rear end of the piston rod. The piston has a threaded portion that engages with the outer circumferential surface of the piston rod and a limiting portion sandwiched between the piston rod and the bolt. The inner diameter of the limiting portion is smaller than the inner diameter of the threaded portion.

[0009] In an optional embodiment of this utility model, the rear end of the piston rod has a constricted section, and the limiting part cooperates with the constricted section.

[0010] In an optional embodiment of this invention, the end of the piston away from the threaded portion extends to the outer periphery of the bolt.

[0011] In an optional embodiment of this utility model, one end of the piston rod has a threaded hole that mates with a bolt, and the inner bottom surface of the threaded hole has a tapered chamfer.

[0012] This utility model also proposes a hydraulic cylinder, including a cylinder body and the piston assembly described above, wherein the piston divides the interior of the cylinder body into a rod-side chamber and a rodless chamber that are not interconnected.

[0013] In an optional embodiment of this utility model, a sealing ring and multiple guide rings are provided between the radial clearance of the piston and the cylinder.

[0014] In an optional embodiment of this utility model, the cylinder body includes a cylinder barrel and a cylinder cover that seals one end of the cylinder barrel.

[0015] In an optional embodiment of this utility model, the bolt is fixed to one end of the piston rod facing the cylinder head, and the end face of the bolt facing the cylinder head is provided with an anti-collision pad.

[0016] In an optional embodiment of this utility model, the end face of the bolt facing the cylinder head has a mounting groove, and the anti-collision pad is fixed in the mounting groove.

[0017] The beneficial effects of this utility model are: (1) The piston assembly of this utility model adopts a double threaded connection structure, which has a good relaxation effect. Since the limiting part is located at the rear end of the piston thread, the cross-sectional size of the limiting part can be increased without affecting the strength of the piston thread, thereby increasing the extrusion area and reducing the stress on the end face of the limiting part. For oil cylinders with large cylinder rod diameter differences, the structure is more reliable and the size arrangement is smaller.

[0018] (2) The hydraulic cylinder of this utility model has a small size arrangement space, the piston axial length can be increased, and a large number of guide rings can be installed, which reduces the friction between the piston and the cylinder body. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 This is a structural schematic diagram of a specific embodiment of the piston assembly described in this utility model.

[0021] In the diagram, 1 is the cylinder block, 101 is the cylinder barrel, 102 is the cylinder head, 2 is the piston rod, 201 is the necked section, 3 is the piston, 301 is the threaded part, 302 is the limiting part, 4 is the bolt, 401 is the mounting groove, 5 is the sealing ring, 6 is the guide ring, 7 is the threaded hole, 701 is the tapered chamfer, and 8 is the anti-collision pad. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0023] Example 1 like Figure 1 As shown, a piston assembly includes a piston rod 2, a piston 3, and a bolt 4. The bolt 4 is threadedly connected to the rear end of the piston rod 2, where the rear end refers to the end that extends in the opposite direction to the piston rod 2. The piston 3 has a threaded portion 301 that is threaded to the outer circumferential surface of the piston rod 2 and a limiting portion 302 that is sandwiched between the piston rod 2 and the bolt 4. The inner diameter of the limiting portion 302 is smaller than the inner diameter of the threaded portion 301.

[0024] This invention features a double-threaded mating structure, including a threaded engagement between the bolt 4 and the piston rod 2, and a threaded engagement between the threaded portion 301 and the piston rod 2. The limiting portion 302 of the piston 3 serves as an axial limiting element. Two threads at both ends of the limiting portion 302 provide a locking effect. Compared to the single-threaded locking in the prior art, this invention offers better anti-loosening performance and reduces the locking requirements of each threaded engagement, thereby reducing the stress on the limiting end. Secondly, the mating surface between the bolt 4 and the piston rod 2 is located inside the piston rod 2, resulting in a smaller axial length occupied by the bolt 4. Therefore, the overall piston structure size is small, allowing for a larger piston 3. This makes the structure more robust, especially for cylinders with large differences in cylinder rod diameter. Furthermore, since the limiting portion 302 is located at the rear end of the threaded portion 301, the threaded portion 301 can directly connect to the main body of the piston rod 2. Therefore, the radial dimension of the threaded portion 301 is equal to the outer diameter of the piston rod 2, resulting in a larger threaded connection surface. This reduces torque and prevents thread lock-up. Furthermore, since the setting of the limiting part 302 does not affect the thread size of the threaded part 301, the inner diameter of the limiting part 302 can be smaller, thereby increasing the end size of the limiting part 302 and reducing the stress on the positioning surface.

[0025] like Figure 1As shown, a constricted section 201 is provided at the rear end of the piston rod 2, and the limiting part 302 cooperates with the constricted section 201.

[0026] Example 2 Based on Embodiment 1, the end of the piston 3 away from the threaded portion 301 extends to the outer periphery of the bolt 4, such as... Figure 1 As shown, the right end of piston 3 extends to the outer periphery of bolt 4, which increases the axial length of piston 3 and allows for the installation of a larger number of guide rings 6, thereby reducing friction between piston 3 and cylinder 1.

[0027] Example 3 Based on the above embodiment, one end of the piston rod 2 has a threaded hole 7 that mates with the bolt 4. The inner bottom surface of the threaded hole 7 has a tapered chamfer 701. The tapered chamfer 701 is provided to facilitate the smooth withdrawal of the cutting tool when machining the thread and to prevent incomplete thread termination.

[0028] Example 4 A hydraulic cylinder, comprising a cylinder body 1 and the piston assembly described above, wherein a piston 3 divides the interior of the cylinder body 1 into a rod-side chamber and a rodless chamber that are not interconnected.

[0029] The cylinder block 1 typically includes a cylinder barrel 101 and a cylinder head 102 that is sealed at one end of the cylinder barrel 101. Bolt 4 is fixed to the piston rod 2 at the end facing the cylinder head 102.

[0030] Since the piston 3 needs to divide the cylinder 1 into mutually isolated rod chambers and rodless chambers, a sealing effect needs to be ensured between the piston 3 and the cylinder 1. For this purpose, a sealing ring 5 is provided between the piston 3 and the cylinder 1 in the radial clearance. In addition, in order to reduce the friction between the piston 3 and the cylinder 1, multiple guide rings 6 are also provided between the piston 3 and the cylinder 1 in the radial clearance.

[0031] Example 5 Based on Embodiment 4, a crash pad 8 is provided on the end face of the bolt 4 facing the cylinder head 102. This is used to reduce noise from the impact between the bolt 4 and the cylinder head 102. The crash pad 8 is installed in such a way that the end face of the bolt 4 facing the cylinder head 102 has a mounting groove 401, and the crash pad 8 is fixed within the mounting groove 401. This increases the contact area between the crash pad 8 and the bolt 4, improves the connection strength, and prevents the crash pad 8 from falling off. In its free state, the crash pad 8 protrudes from the end of the bolt 4, allowing it to impact the cylinder head 102 first and deform for cushioning.

[0032] This invention provides hydraulic cylinders with more stable, safe, and reliable working performance, especially improving the lifespan of hydraulic cylinders when there is a large difference in cylinder rod diameter, thereby improving the use of mechanical equipment and achieving better quality performance.

[0033] In this specification, the illustrative expressions of the terms do not necessarily refer to the same embodiments. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0034] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A piston assembly, characterized in that: The device includes a piston rod (2), a piston (3), and a bolt (4). The bolt (4) is threaded to the rear end of the piston rod (2). The piston (3) has a threaded portion (301) that engages with the outer circumferential surface of the piston rod (2) and a limiting portion (302) that is sandwiched between the piston rod (2) and the bolt (4). The inner diameter of the limiting portion (302) is smaller than the inner diameter of the threaded portion (301).

2. The piston assembly according to claim 1, characterized in that: The piston rod (2) has a constricted section (201) at its rear end, and the limiting part (302) cooperates with the constricted section (201).

3. The piston assembly according to claim 1, characterized in that: The piston (3) extends from the threaded portion (301) to the outer periphery of the bolt (4), and there is a gap between the piston (3) and the outer periphery of the bolt (4).

4. The piston assembly according to claim 1, characterized in that: One end of the piston rod (2) has a threaded hole (7) that mates with a bolt (4), and the inner bottom surface of the threaded hole (7) has a tapered chamfer (701).

5. A hydraulic cylinder, characterized in that: Includes a cylinder (1) and a piston assembly as described in any one of claims 1-4, wherein the piston (3) divides the interior of the cylinder (1) into non-communicating rod chambers and rodless chambers.

6. The hydraulic cylinder according to claim 5, characterized in that: The cylinder body (1) includes a cylinder barrel (101) and a cylinder head (102) that is sealed at one end of the cylinder barrel (101).

7. The hydraulic cylinder according to claim 6, characterized in that: The bolt (4) is fixed to one end of the piston rod (2) facing the cylinder head (102), and the end face of the bolt (4) facing the cylinder head (102) is provided with an anti-collision pad (8).

8. The hydraulic cylinder according to claim 7, characterized in that: The bolt (4) has a mounting groove (401) on its end face facing the cylinder head (102), and the anti-collision pad (8) is fixed in the mounting groove (401).

9. The hydraulic cylinder according to claim 5, characterized in that: A sealing ring (5) and multiple guide rings (6) are provided between the piston (3) and the cylinder (1) in the radial gap.

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