Piston assembly, its assembly method, disassembly method, and hydraulic cylinder

Abstract

The present invention relates to the field of hydraulic cylinders, and discloses a piston assembly, an assembly method, a disassembly method thereof, and a hydraulic cylinder. The piston assembly includes a piston rod (1), a piston portion (7), a buffer sleeve (4), a snap ring (6), and a retaining ring (5). The piston rod (1) includes a buffer section (3), a main body section (2), and a first stepped surface. The inner circumferential surface of the buffer sleeve (4) is provided with a second stepped surface and is sleeved on the buffer section (3). The buffer section (3) is provided with an annular groove, the retaining ring (5) is arranged in the annular groove and abuts against the second stepped surface, and the snap ring (6) is located between the first stepped surface and the buffer sleeve (4). Through the above technical solution, the matching structure of the piston rod and the buffer sleeve is simpler. Instead of machining the inner hole of the piston rod, external cylindrical machining is carried out. The tool shank of the turning tool is not limited by the inner hole diameter, and the processed dimensions are convenient to measure, which is conducive to improving the machining accuracy and quality.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic cylinders, and in particular to a piston assembly, and relates to an assembly method and a disassembly method of the piston assembly, and also relates to a hydraulic cylinder. Background Art

[0002] For the bottom-end buffering of the prior art, generally the form of a buffer plunger is adopted, and the detailed functions are as follows:

[0003] The outer wall surface of the buffer plunger and the inner wall surface of the cylinder bottom cooperate to form a predetermined throttle oil passage; the hydraulic oil flows back through the throttle oil passage, and the hydraulic oil pressure in the buffer chamber increases, thereby reducing the movement speed of the piston rod and avoiding large impacts generated between the piston rod and the cylinder bottom.

[0004] In the existing buffer device, a blind hole and a radial through hole communicating with the blind hole are formed on the end surface of the piston rod, an arc groove is formed on the outer periphery of the buffer plunger, the buffer plunger is inserted into the blind hole, and is stuck in the arc groove by a steel ball located in the radial through hole. It is easy to load the steel ball, but difficult to pour out the steel ball, and it is difficult to replace the buffer plunger; in addition, the inner wall of the piston rod for assembling the buffer plunger and the arc groove on the buffer plunger for accommodating the steel ball are relatively difficult to machine. Summary of the Invention

[0005] The object of the present invention is to provide a piston assembly to solve the problems that the piston rod is not easy to machine and the assembly difficulty is large.

[0006] To achieve the above object, on the one hand, the present invention provides a piston assembly, wherein the piston assembly includes a piston rod, a piston portion, a buffer sleeve, a snap ring and a retaining ring. The piston rod includes a buffer section with a smaller outer diameter, a main body section with a larger outer diameter and a first step surface. The inner peripheral surface of the buffer sleeve is provided with a second step surface and is sleeved on the buffer section. An annular groove is provided at one end of the buffer section away from the main body section. The retaining ring is arranged in the annular groove and abuts against the second step surface. The snap ring is located between the first step surface and the buffer sleeve. The piston portion is sleeved on the main body section and the snap ring.

[0007] Optionally, the axial dimension of the snap ring is greater than the distance between the second step surface and the end face of the buffer sleeve away from the snap ring.

[0008] Optionally, the snap ring is a C-shaped ring with an opening, and the retaining ring is a C-shaped ring with an opening.

[0009] Optionally, the piston portion is sleeved on the snap ring and a part of the buffer sleeve.

[0010] Optionally, a radial oil guiding groove is provided on the end face of the piston portion that can be engaged with the cylinder bottom.

[0011] Optionally, a sealing groove is provided on the buffer section between the annular groove and the first step surface, and a sealing ring is provided in the sealing groove.

[0012] Optionally, a flat cut surface is provided on the outer periphery of the end of the buffer sleeve away from the main body section, and the distance between the flat cut surface and the central axis of the buffer sleeve gradually decreases in the direction of the main body section towards the buffer section.

[0013] In addition, the present invention also provides an assembly method for a piston assembly, wherein the piston assembly is the piston assembly described in the above solution, and the assembly method includes:

[0014] S1, axially sleeving the buffer sleeve on the buffer section;

[0015] S2, moving the buffer sleeve towards the first step surface to expose the annular groove, setting the retaining ring in the annular groove, and then moving the buffer sleeve away from the first step surface so that the second step surface abuts against the retaining ring;

[0016] S3, sleeving the snap ring between the buffer sleeve and the first step surface;

[0017] S4, axially moving the piston part and sleeving it on the main body section and the snap ring.

[0018] In addition, the present invention also provides a disassembly method for a piston assembly, characterized in that the piston assembly is the piston assembly described in the above solution, and the disassembly method includes:

[0019] S1. Axially move the piston part to disassemble the piston part from the piston rod;

[0020] S2. Disassemble the snap ring;

[0021] S3. Move the buffer sleeve towards the first step surface to expose the retaining ring, and disassemble the retaining ring;

[0022] S4. Axially move the buffer sleeve to disassemble the buffer sleeve from the piston rod.

[0023] In addition, the present invention also provides a hydraulic cylinder, wherein the hydraulic cylinder is provided with the piston assembly described in the above solution.

[0024] Through the above technical solution, the matching structure of the piston rod and the buffer sleeve is simpler. It is not necessary to machine the inner hole of the piston rod, but instead to machine the outer circle. The tool holder of the turning tool is not restricted by the inner hole diameter, and the processed dimensions are convenient for measurement, which is conducive to improving the processing accuracy and quality. Description of the Drawings

[0025] Figure 1 is a partial cross-sectional view of the piston assembly according to an embodiment of the present invention;

[0026] Figure 2 is a schematic structural view of the buffer sleeve according to an embodiment of the present invention;

[0027] Figure 3 is a cross-sectional view of a partial structure of the hydraulic cylinder according to an embodiment of the present invention.

[0028] Description of reference numerals

[0029] 1 piston rod 2 main body section

[0030] 3 buffer section 4 buffer sleeve

[0031] 5 retaining ring 6 snap ring

[0032] 7 piston part 8 sealing ring

[0033] 9 bolt 10 steel ball

[0034] 11 oil inlet / outlet 12 cylinder bottom

[0035] 13 valve core 14 spring

[0036] 15 plug 16 oil hole

[0037] 17 buffer cavity Detailed description of the specific embodiment

[0038] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0039] The present invention provides a piston assembly, wherein the piston assembly includes a piston rod 1, a piston part 7, a buffer sleeve 4, a snap ring 6 and a retaining ring 5. The piston rod 1 includes a buffer section 3 with a smaller outer diameter, a main body section 2 with a larger outer diameter and a first step surface. The inner peripheral surface of the buffer sleeve 4 is provided with a second step surface and is sleeved on the buffer section 3. An annular groove is provided at one end of the buffer section 3 away from the main body section 2. The retaining ring 5 is arranged in the annular groove and abuts against the second step surface. The snap ring 6 is located between the first step surface and the buffer sleeve 4. The piston part 7 is sleeved on the main body section 2 and the snap ring 6.

[0040] As Figure 3 shown, the buffer sleeve 4 of the piston assembly can be inserted into the inner hole of the cylinder bottom 12, and there is a gap between the buffer sleeve 4 and the inner hole to allow hydraulic oil to flow through. The hydraulic oil can pass through the oil inlet / outlet 11 to achieve buffering of the piston assembly.

[0041] As shown Figure 1 in the figure, the piston rod 1 includes a main body section 2 and a buffer section 3. A buffer sleeve 4 can be sleeved on the buffer section 3 to facilitate the replacement of the buffer sleeve 4. Among them, a retaining ring 5 is located in an annular groove on the buffer section 3. The inner circumference of the buffer sleeve 4 is formed into two sections and is transitioned by a second step surface. The retaining ring 5 can stop the second step surface to limit the axial movement of the buffer sleeve 4 away from the main body section 2. A snap ring 6 is arranged between the buffer sleeve 4 and the main body section 2. When installing the retaining ring 5, it is necessary to move the buffer sleeve 4 to expose the annular groove. Correspondingly, when the buffer sleeve 4 moves to make the second step surface contact the retaining ring 5, there is a gap between it and the first step surface. The snap ring 6 can fill this gap. The piston portion 7 is generally formed in a sleeve shape, which is sleeved on the main body section 2 and covers at least part of the snap ring 6 to prevent the snap ring 6 from detaching from the buffer section 3.

[0042] Compared with the form of inserting a buffer plunger into a blind hole on the end face of the piston rod in the prior art, the matching structure of the piston rod and the buffer sleeve in this solution is simpler. It is not necessary to machine the inner hole of the piston rod, but instead, external cylindrical machining is carried out. The tool holder of the turning tool is not restricted by the inner hole diameter, and the processed dimensions are convenient for measurement, which is conducive to improving the machining accuracy and quality.

[0043] Furthermore, the axial dimension of the snap ring 6 is greater than the distance between the second step surface and the end face of the buffer sleeve 4 far from the snap ring 6. The axial dimension of the snap ring 6 corresponds to the distance between the buffer sleeve 4 and the first step surface. When installing the retaining ring 5, the buffer sleeve 4 needs to be moved to a position close to the first step surface, so that the end face of the buffer sleeve 4 far from the snap ring 6 is located on one side of the annular groove, that is, the annular groove on the buffer section 3 is exposed, so as to allow the retaining ring 5 to be sleeved in the annular groove.

[0044] Among them, the snap ring 6 is a C-shaped ring with an opening, and the retaining ring 5 is a C-shaped ring with an opening. This allows the snap ring 6 to be directly clamped between the buffer sleeve 4 and the main body section 2 in the radial direction, and allows the retaining ring 5 to be clamped in the annular groove in the radial direction. The snap ring 6 and the retaining ring 5 can be made of metal, which has a certain elastic deformation ability to allow them to be radially sleeved on the target position of the buffer section 3.

[0045] Among them, the piston portion 7 is sleeved on the snap ring 6 and part of the buffer sleeve 4. The piston portion 7 extends to the buffer sleeve 4 to fully cover the snap ring 6 and prevent the snap ring 6 from radially detaching from the buffer section 3.

[0046] Among them, referring Figure 1 to the figure, radial through holes are formed on the piston portion 7, and steel balls 10 and bolts 9 can be arranged therein. Part of the steel balls 10 are located in grooves on the outer circumference of the main body section 2 to achieve axial limit of the main body section 2.

[0047] Among them, on the end face of the piston part 7 that can be joined to the cylinder bottom, there are radial oil guiding grooves. The end face of the piston part 7 facing the cylinder bottom may include two radial steps. The inner ring part can be joined to the cylinder bottom, and radial oil guiding grooves are formed on the inner ring part to allow hydraulic oil to reach the outer circumference of the piston rod 1 and enter the space between the buffer sleeve 4 and the inner hole of the cylinder bottom; while the outer ring part is spaced from the cylinder bottom to form a buffer cavity 17, as Figure 3 shown. The buffer cavity 17 is communicated with the inner hole through another oil hole 16 on the cylinder bottom 12. The oil hole 16 includes an axial part and a radial part. A valve core 13, a spring 14, and a plug 15 are arranged in the radial part to form a one-way valve. A through hole communicating the radial part and the axial part is formed on the valve core 13. When the valve core 13 moves downward, the radial part and the axial part can also be communicated. The movement of the valve core 13 can realize the communication of the hydraulic oil between the buffer cavity 17 and the inner hole, achieving buffering.

[0048] In addition, a sealing groove is arranged on the buffer section 3 between the annular groove and the first step surface, and a sealing ring 8 is arranged in the sealing groove. The sealing ring 8 can prevent hydraulic oil from entering the inner hole through the gap between the buffer sleeve 4 and the buffer section 3.

[0049] Among them, a flat cut surface is arranged on the outer circumference of one end of the buffer sleeve 4 away from the main body section 2, and the distance between the flat cut surface and the central axis of the buffer sleeve 4 gradually decreases in the direction of the main body section 2 facing the buffer section 3. As Figure 2 shown, the part between the dotted line and the slanted line is the cut-off part. By cutting off a part of the buffer sleeve 4 to form a cut surface, the gap between the buffer sleeve 4 and the inner hole of the cylinder bottom 12 is changed. In particular, in the direction of the main body section 2 facing the buffer section 3, the distance between the flat cut and the central axis decreases, that is, the gap gradually increases (corresponding to the change in the flow area). When hydraulic oil enters the inner hole from the oil inlet and outlet 11, such a gap can buffer the hydraulic oil and avoid the situation where the gap suddenly becomes very small.

[0050] In addition, the present invention also provides an assembly method for a piston assembly. Among them, the piston assembly is the piston assembly described in the above solution, and the assembly method includes:

[0051] S1, axially sleeving the buffer sleeve 4 on the buffer section 3;

[0052] S2, moving the buffer sleeve 4 towards the first step surface to expose the annular groove, arranging the retaining ring 5 in the annular groove, and then moving the buffer sleeve 4 away from the first step surface so that the second step surface abuts against the retaining ring 5;

[0053] S3, sleeving the snap ring 6 between the buffer sleeve 4 and the first step surface;

[0054] S4. Axially move the piston part 7 and sleeved it on the main body section 2 and the snap ring 6.

[0055] Wherein, axially move the buffer sleeve 4 relative to the buffer section 3 and sleeved it on the buffer section 3. And before sleeving the buffer sleeve 4, the first sealing ring 8 can be set at the target position; when installing the retaining ring 5, it is necessary to move the buffer sleeve 4 to one side of the annular groove, then snap the retaining ring 5 (such as a C-ring) into the annular groove, and then axially move the buffer sleeve 4 to cover the retaining ring 5 so that the second step surface engages with the retaining ring 5; the snap ring 6 is the above-mentioned C-ring and can be radially arranged between the buffer sleeve 4 and the first step surface; after the piston part 7 is sleeved on the main body section 2 and the snap ring 6, the relative fixation between the piston part 7 and the piston rod 1 is realized by the above-mentioned bolt 9 and steel ball 10.

[0056] It can be seen from the above assembly method that the installation of the buffer sleeve is simple and fast, which is convenient for installation.

[0057] In addition, the present invention also provides a disassembly method for a piston assembly, wherein, the piston assembly is the piston assembly described in the above solution, and the disassembly method includes:

[0058] S1. Axially move the piston part 7 to disassemble the piston part 7 from the piston rod 1;

[0059] S2. Disassemble the snap ring 6;

[0060] S3. Move the buffer sleeve 4 towards the first step surface to expose the retaining ring 5 and disassemble the retaining ring 5;

[0061] S4. Axially move the buffer sleeve 4 to disassemble the buffer sleeve 4 from the piston rod 1.

[0062] This disassembly method is the opposite operation steps of the above assembly method, and will not be described in detail here.

[0063] In addition, the present invention also provides a hydraulic cylinder, wherein, the hydraulic cylinder is provided with the piston assembly described in the above solution.

[0064] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any suitable combination of each specific technical feature. In order to avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. But these simple modifications and combinations should equally be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. An assembly method for a piston assembly, characterized in that, The piston assembly includes a piston rod (1), a piston part (7), a buffer sleeve (4), a snap ring (6) and a retaining ring (5). The piston rod (1) includes a buffer section (3) with a smaller outer diameter, a main body section (2) with a larger outer diameter, and a first step surface. The inner peripheral surface of the buffer sleeve (4) is provided with a second step surface and is sleeved on the buffer section (3). An annular groove is provided at one end of the buffer section (3) away from the main body section (2). The retaining ring (5) is arranged in the annular groove and abuts against the second step surface. The snap ring (6) is located between the first step surface and the buffer sleeve (4). The piston part (7) is sleeved on the main body section (2) and the snap ring (6). The axial dimension of the snap ring (6) is greater than the distance between the second step surface and the end face of the buffer sleeve (4) away from the snap ring (6). The snap ring (6) is a C-shaped ring with an opening. The retaining ring (5) is a C-shaped ring with an opening. The piston part (7) is sleeved on the snap ring (6) and a part of the buffer sleeve (4). The assembly method includes: S1, axially sleeve the buffer sleeve (4) on the buffer section (3); S2, move the buffer sleeve (4) towards the first step surface to expose the annular groove, arrange the retaining ring (5) in the annular groove, and then move the buffer sleeve (4) away from the first step surface so that the second step surface abuts against the retaining ring (5); S3, sleeve the snap ring (6) between the buffer sleeve (4) and the first step surface; S4, axially move the piston part (7) and sleeve it on the main body section (2) and the snap ring (6).

2. The assembling method of the piston assembly according to claim 1, wherein The end face of the piston part (7) that can be joined to the bottom of the cylinder is provided with a radial oil guiding groove.

3. The assembling method of the piston assembly according to claim 1, characterized in that, A sealing groove is provided on the buffer section (3) between the annular groove and the first step surface, and a sealing ring (8) is arranged in the sealing groove.

4. The assembly method of the piston assembly according to claim 1, characterized in that, A flat cut surface is provided on the outer periphery of the end of the buffer sleeve (4) away from the main body section (2), and the distance between the flat cut surface and the central axis of the buffer sleeve (4) gradually decreases in the direction of the main body section (2) towards the buffer section (3).

5. A method for disassembling a piston assembly, characterized in that, The piston assembly includes a piston rod (1), a piston part (7), a buffer sleeve (4), a snap ring (6) and a retaining ring (5). The piston rod (1) includes a buffer section (3) with a smaller outer diameter, a main body section (2) with a larger outer diameter, and a first stepped surface. The inner peripheral surface of the buffer sleeve (4) is provided with a second stepped surface and is sleeved on the buffer section (3). An annular groove is provided at one end of the buffer section (3) away from the main body section (2). The retaining ring (5) is arranged in the annular groove and abuts against the second stepped surface. The snap ring (6) is located between the first stepped surface and the buffer sleeve (4). The piston part (7) is sleeved on the main body section (2) and the snap ring (6). The axial dimension of the snap ring (6) is greater than the distance between the second stepped surface and the end face of the buffer sleeve (4) away from the snap ring (6). The snap ring (6) is a C-shaped ring with an opening. The retaining ring (5) is a C-shaped ring with an opening. The piston part (7) is sleeved on the snap ring (6) and part of the buffer sleeve (4). The disassembly method includes: S1. Axially move the piston part (7) to disassemble the piston part (7) from the piston rod (1); S2. Disassemble the snap ring (6); S3. Move the buffer sleeve (4) towards the first stepped surface to expose the retaining ring (5), and disassemble the retaining ring (5); S4. Axially move the buffer sleeve (4) to disassemble the buffer sleeve (4) from the piston rod (1).

6. The disassembly method of the piston assembly according to claim 5, characterized in that, The piston part (7) is capable of being joined to the end face of the cylinder bottom and is provided with a radial oil guiding groove.

7. The disassembly method of the piston assembly according to claim 5, characterized in that, A sealing groove is provided on the buffer section (3) between the annular groove and the first stepped surface, and a sealing ring (8) is arranged in the sealing groove.

8. The disassembly method of the piston assembly according to claim 5, characterized in that, A flat cut surface is provided on the outer periphery of the end of the buffer sleeve (4) away from the main body section (2), and the distance between the flat cut surface and the central axis of the buffer sleeve (4) gradually decreases in the direction of the main body section (2) towards the buffer section (3).

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