Piston static sealing system of pressure-impact-resistant engineering machinery hydraulic cylinder

Abstract

The invention discloses a piston static sealing system of a pressure-impact-resistant engineering machinery hydraulic cylinder, which comprises a piston rod, a piston and a static seal, the piston rod comprises a rod body and a connector arranged at one end of the rod body, the diameter of the connector is smaller than that of the rod body, the piston is arranged on the connector, and the piston is in contact with the end of the rod body; a first-stage seal is formed in the contact area of the piston and the end of the rod body, the static seal is arranged between the connecting body and the piston to form a second-stage seal, and by arranging the first-stage seal, the problem of aging of the static seal is solved; the sealing chamfer of the rod body of the piston rod and the chamfer at the end part of the piston mounting hole can generate elastic deformation under the action of smaller tightening torque, and are tightly attached to each other to form a metal hard sealing surface, so that the sealing performance is improved, the mounting and the dismounting are easy, the reliability of the hydraulic cylinder is also improved, the structural universality is strong, and the cost is low. The method has reference significance for design of other similar products.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic cylinders, and in particular relates to a piston static sealing system of a pressure-impact resistant engineering machinery hydraulic cylinder. Background Art

[0002] At present, the service life and mean trouble-free working time of high-speed and high-pressure hydraulic cylinders for construction machinery, represented by loaders and excavators, on the market generally do not meet the indicators of similar foreign benchmark products. The main feedback problem is that the static seal between the piston and the piston rod operates under long-term high speed, high pressure and high temperature. The alternating impact pressure and high temperature have a great impact on the service life of the static seal, resulting in internal leakage of the hydraulic cylinder and failure to use normally.

[0003] The existing patent with the publication (announcement) number CN208719346U is a patent for a static sealing structure for a hydraulic cylinder piston of an excavator, including a piston rod, a piston and a sealing device; the left end of the piston rod is provided with a first step drawer, the right section of the first step drawer is provided with an external thread, and the left section of the first step drawer is a smooth axis; the right section of the inner wall of the piston is provided with an internal thread, and the left section of the inner wall of the piston is a smooth axis, and the piston is connected to the first step drawer through internal and external threads; the right section of the outer circumferential surface of the piston is provided with an operating step, and the operating step is polygonal; a fastening screw is installed on the operating step, and a positioning groove matching the fastening screw is opened at the right end of the first step drawer; the diameter of the left section of the outer circumferential surface of the piston is larger than the operating step, and the sealing device is installed on the left section of the outer circumferential surface of the piston. The structure is compact, the cost is low, and the integrated piston structure is adopted, the structure is streamlined, and the processing and assembly are convenient, which improves the reliability of the static sealing of the piston.

[0004] However, there are still the following deficiencies in this patent: 1. There is no traditional O-ring as a static seal between the piston and the piston rod. Only the end face of the piston rod head and the piston end face are mechanically matched. A large tightening torque is applied to the piston to make the piston and the piston rod positioning surface close together. The positioning surface produces a certain deformation under the action of the large tightening torque to achieve the static sealing function; 2. The above mechanical hard seal structure generally has a large contact area of ​​the annular seal. In order to keep the piston and the piston rod positioning surface close together, a very large torque needs to be applied, generally 15000-25000 N*M, to ensure the deformation and sealing performance between the mating surfaces. The requirements for torque tightening equipment are relatively high, and a large torque tightening machine is required, which has a high equipment cost. 3. This structure is tightened with a large torque, so when the product is repaired later, the piston is not easy to disassemble and maintenance is not convenient. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a piston static sealing system for a pressure-shock-resistant engineering machinery hydraulic cylinder, which focuses on solving the problem that hydraulic cylinders used in high-pressure and high-speed working conditions of engineering machinery (loaders, excavators, etc.) are repeatedly subjected to high pressure due to: ①, frequent high-speed reciprocating motion, resulting in repeated high pressure impacts in the two chambers; ②, conventional O-ring static seals are used under long-term high temperature and alternating high-pressure impact conditions, resulting in accelerated aging of the O-rings, and then leading to the failure of the piston static sealing system. This product structure improves the reliability of the hydraulic cylinder and has strong structural versatility, which is of reference significance for the design of other similar products.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder, comprising: a piston rod, a piston, and a static seal. The piston rod comprises: a rod body and a connecting body arranged at one end of the rod body, the diameter of the connecting body is smaller than the diameter of the rod body, the piston is arranged on the connecting body so that the piston contacts the end of the rod body, and the contact area between the piston and the end of the rod body forms a primary seal, and the static seal is arranged between the connecting body and the piston to form a secondary seal.

[0007] Furthermore, the connecting body of the piston rod is coaxially arranged with the rod body.

[0008] Furthermore, a mounting hole is provided at the center of the piston, and the piston is sleeved on the connecting body of the piston rod through the mounting hole.

[0009] Furthermore, the primary seal is a conical structure, that is, the contact area between the rod end and the piston is provided with a conical chamfer, and the contact area between the piston mounting hole end and the rod body is provided with a conical chamfer, and sealing is achieved by the mutual cooperation between the conical chamfers of the rod body and the piston mounting hole end.

[0010] Furthermore, the chamfer at the end of the piston mounting hole is fitted onto the chamfer at the end of the rod body.

[0011] Furthermore, the chamfer at the end of the rod body is a double-angle chamfer, which is divided into a gap chamfer and a sealing chamfer. The gap chamfer and the sealing chamfer are arranged in parallel at the end of the rod body, and the sealing chamfer is arranged close to the end face of the rod body.

[0012] The width of the sealing chamfer is 1.5-2.5mm, the surface roughness of the gap chamfer and sealing chamfer is Ra0.8, and the circular runout is Ø0.03mm.

[0013] Furthermore, the included angle between the gap chamfered surface and the outer surface of the rod body is greater than the included angle between the sealing chamfered surface and the outer surface of the rod body.

[0014] Furthermore, the angle between the chamfered surface at the end of the piston mounting hole and the surface of the connecting body of the piston rod is equal to the angle between the chamfered surface of the gap and the outer surface of the rod body. The surface roughness of the chamfered surface at the end of the piston mounting hole reaches Ra0.8, and the circular runout reaches Ø0.03mm.

[0015] Furthermore, the connecting body and the rod body in the piston rod are an integrally formed structure, and the connecting body and the rod body support are in an arc-shaped transition.

[0016] Furthermore, the connector is provided with threads for installing a locking nut, and the piston is pressed onto the rod body through the locking nut.

[0017] The beneficial effects of the present invention are: utilizing the contact between the piston and the piston rod as a primary metal seal, and arranging a static seal between the piston and the piston rod as a secondary seal, and the double-insurance static seal structure improves its sealing performance. By arranging a primary seal, the problem of accelerated aging of the O-ring caused by the conventional O-ring static seal under long-term high temperature and alternating high-pressure impact conditions, which in turn causes the piston static sealing system to fail, is solved. By adopting a double-angle chamfer for the chamfer at the end of the piston rod, elastic deformation can occur between the sealing chamfer of the piston rod body and the chamfer at the end of the piston mounting hole under a smaller tightening torque, so that they are tightly attached to each other to form a metal hard sealing surface, thereby improving the sealing performance, and being easy to install and disassemble, with a compact structure, low cost, and convenient processing and assembly, thereby improving the reliability of the piston static seal, and at the same time also improving the reliability of the hydraulic cylinder and the strong structural versatility, which has reference significance for the design of other similar products. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the use structure of the present invention; Figure 2 for Figure 1 A schematic diagram of the partially enlarged structure of I in the figure; Figure 3 for Figure 2 A schematic diagram of the partially enlarged structure; Figure 4 for Figure 3 Schematic diagram of the local structure of the piston rod; Figure 5 for Figure 3 Schematic diagram of the partial structure of the middle piston; In the figure: 1. Piston rod; 2. Piston; 3. Static seal; 4. Locking nut. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0021] like Figure 1-5 As shown, a piston static sealing system of a pressure-shock resistant engineering machinery hydraulic cylinder includes: a piston rod 1, a piston 2, and a static seal 3. The piston rod 1 includes: a rod body and a connector arranged at one end of the rod body, the diameter of the connector is smaller than the diameter of the rod body, the piston 2 is arranged on the connector, so that the piston 2 contacts the end of the rod body, and the contact area between the piston 2 and the end of the rod body forms a primary seal, and the static seal 3 is arranged between the connector and the piston 2 to form a secondary seal.

[0022] A mounting hole is provided at the center of the piston 2, and the piston 2 is mounted on the connecting body of the piston rod 1 through the mounting hole. The connecting body of the piston rod 1 is coaxially arranged with the rod body to ensure that the mounting hole of the piston 2 can contact the rod body after the piston 2 is installed to form a primary seal.

[0023] The primary seal is a conical structure, that is, the contact area between the rod end and the piston 2 is provided with a conical chamfer, and the contact area between the piston 2 mounting hole end and the rod body is provided with a conical chamfer. The sealing is achieved by the mutual cooperation between the conical chamfers of the rod body and the piston 2 mounting hole end.

[0024] The chamfer at the end of the mounting hole of the piston 2 is fitted onto the chamfer at the end of the rod body, and primary sealing is achieved through the cooperation of this structure.

[0025] The chamfer at the end of the rod body is a double-angle chamfer, which is divided into a gap chamfer and a sealing chamfer. The gap chamfer and the sealing chamfer are arranged in parallel at the end of the rod body, and the sealing chamfer is arranged close to the end face of the rod body.

[0026] The width of the sealing chamfer is 1.5-2.5mm, the surface roughness of the gap chamfer and sealing chamfer is Ra0.8, and the circular runout is Ø0.03mm.

[0027] The included angle b° between the gap chamfered surface and the outer surface of the rod body is greater than the included angle a° between the sealing chamfered surface and the outer surface of the rod body.

[0028] The angle b° between the chamfered surface at the end of the piston 2 mounting hole and the surface of the connecting body of the piston rod 1 is equal to the angle b° between the chamfered surface of the gap and the outer surface of the rod body. The surface roughness of the chamfered surface at the end of the piston 2 mounting hole reaches Ra0.8, and the circular runout reaches Ø0.03mm.

[0029] Among them, the angle a° is 3°-5° smaller than b°.

[0030] The connector and the rod body in the piston rod 1 are an integrally formed structure, and the connector and the rod body support are in an arc-shaped transition; the connector is provided with threads for installing a locking nut 4, and the piston 2 is pressed onto the rod body through the locking nut 4.

[0031] The static seal 3 is an O-ring. A mounting groove is provided inside the mounting hole of the piston 2. The O-ring is installed in the groove to play the role of a static seal 3 between the piston 2 and the piston rod 1. The sealing structure is a static seal 3 principle and structure in the form of a traditional seal to form a secondary seal. The locking nut 4 is connected to the connector of the piston rod 1 by a thread. The locking nut 4 has a hexagonal structure on the outside, which is convenient for applying torque through a torque tightening machine to assemble the piston 2 on the piston rod 1 and tighten it through the locking nut 4. A torque tightening machine is used to apply a conventional torque (generally 1000-2000N*M) to cause elastic deformation between the sealing chamfer of the piston rod 1 and the chamfer at the end of the mounting hole of the piston 2, so that they are tightly attached to each other to form a metal hard sealing surface, forming a primary seal between the piston rod 1 and the piston 2.

[0032] The piston 2 static seal 3 system of the pressure-shock-resistant engineering machinery hydraulic cylinder has improved the reliability of the hydraulic cylinder and increased the structural versatility, which has reference significance for the design of other similar products.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A piston static sealing system for a pressure-shock-resistant engineering machinery hydraulic cylinder, characterized in that: include: A piston rod, a piston, and a static seal. The piston rod includes: a rod body and a connecting body arranged at one end of the rod body. The diameter of the connecting body is smaller than the diameter of the rod body. The piston is arranged on the connecting body so that the piston contacts the end of the rod body. The contact area between the piston and the end of the rod body forms a primary seal. The static seal is arranged between the connecting body and the piston to form a secondary seal.

2. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 1 is characterized in that: The connecting body of the piston rod is coaxially arranged with the rod body.

3. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 2 is characterized in that: A mounting hole is arranged at the center of the piston, and the piston is sleeved on the connecting body of the piston rod through the mounting hole.

4. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 3 is characterized in that: The primary seal is a conical structure, that is, the contact area between the rod end and the piston is provided with a conical chamfer, and the contact area between the piston mounting hole end and the rod body is provided with a conical chamfer. The sealing is achieved by the mutual cooperation between the conical chamfers of the rod body and the piston mounting hole end.

5. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 4, characterized in that: The chamfer at the end of the piston mounting hole is sleeved onto the chamfer at the end of the rod body.

6. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 4, characterized in that: The chamfer at the end of the rod body is a double-angle chamfer, which is divided into a gap chamfer and a sealing chamfer. The gap chamfer and the sealing chamfer are arranged in parallel at the end of the rod body, and the sealing chamfer is arranged close to the end face of the rod body.

7. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 6, characterized in that: The included angle between the gap chamfered inclined surface and the outer surface of the rod body is greater than the included angle between the sealing chamfered inclined surface and the outer surface of the rod body.

8. A piston static sealing system for a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 6 or 7, characterized in that: The angle between the chamfered surface at the end of the piston mounting hole and the surface of the connecting body of the piston rod is equal to the angle between the chamfered surface of the gap and the outer surface of the rod body.

9. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 1, characterized in that: The connecting body and the rod body in the piston rod are an integrally formed structure, and the connecting body and the rod body support are in an arc-shaped transition.

10. The piston static sealing system of a pressure-shock-resistant engineering machinery hydraulic cylinder according to claim 1, characterized in that: The connecting body is provided with threads for installing a locking nut, and the piston is pressed onto the rod body through the locking nut.

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