Improved piston rod seal

Abstract

The application discloses a piston rod sealing improved structure, which comprises an upper connecting part, a middle part, a lower connecting part, a piston rod and a first sealing part, the upper connecting part, the middle part and the lower connecting part are sequentially arranged from top to bottom, and the piston rod sequentially passes through the upper connecting part, the middle part and the lower connecting part, the first sealing part comprises a pressing piece, a pressing part and sealing oil, the pressing part surrounds the piston rod, the pressing piece compresses the pressing part to shrink to one side of the piston rod, and the sealing oil is arranged between the pressing part and the circumferential surface of the piston rod, and the piston rod sealing improved structure has good sealing effect.

Description

Technical Field

[0001] This invention belongs to the field of piston rod sealing technology, and specifically relates to an improved piston rod sealing structure. Background Technology

[0002] In pneumatic systems, the cylinder piston rod undergoes frequent reciprocating motion. The seals between the piston rod and the cylinder are typically lip seals or combination seals. These pneumatic seals can withstand high pressures, enabling the output of large thrust. However, the higher the pressure, the larger the contact area between the seal and the piston rod, resulting in increased friction. Consequently, under high-pressure applications and frequent reciprocating motion conditions, excessive friction hinders the high-speed response of the cylinder's output motion, and accelerates seal wear, causing the seal to lose its sealing function prematurely. This leads to air leakage and other phenomena in the cylinder, affecting the hydraulic cylinder's performance and operational quality, and even causing serious accidents. Two common methods address this problem: one is to replace the worn seal, but this process affects the hydraulic cylinder's efficiency, and the timing of replacement remains unresolved due to a lack of suitable monitoring methods; the other method is to find ways to compensate for seal wear.

[0003] Chinese invention patent application number 2017103263799 discloses a hydraulic cylinder piston rod seal wear compensation monitoring device. This device uses a Y-shaped sealing ring with an inner cavity as the piston rod seal and employs a fiber optic grating sensor to monitor the contact state changes of the sealing surface of the hydraulic cylinder piston rod in real time. This provides feedback for seal wear compensation, and compensation is performed according to the actual wear state of the hydraulic cylinder piston rod seal. This ensures the sealing performance and operating efficiency of the hydraulic cylinder while minimizing hydraulic oil leakage, thereby extending the service life of the piston rod seal. This solution can change the contact stress between the Y-shaped sealing ring with an inner cavity and the piston rod in real time to improve sealing performance.

[0004] Although the aforementioned patents have a compensatory effect, when the sealing ring wears, the degree of wear in different parts varies, and after the sealing ring expands under input pressure, it is difficult to ensure that all positions are compensated. Therefore, compensating for seal wear cannot effectively solve the sealing problem. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an improved piston rod sealing structure, comprising an upper connecting part, a middle part, a lower connecting part, a piston rod, and a first sealing part. The upper connecting part, the middle part, and the lower connecting part are arranged sequentially, and the piston rod passes through the upper connecting part, the middle part, and the lower connecting part in sequence. The first sealing part includes an extrusion member, an extrusion section, and sealing oil. The extrusion section surrounds the piston rod, and the extrusion member presses the extrusion section to contract towards one side of the piston rod. Sealing oil is provided between the extrusion section and the circumferential surface of the piston rod.

[0006] Preferably, the extrusion component includes a spring and a conductive part. The inner side of the intermediate part is provided with a cavity. The spring is sleeved on the piston rod and the top of the spring is connected to the top of the cavity. The bottom of the spring abuts against the conductive part. The extrusion part is located below the conductive part and a conical surface is provided above the extrusion part. The bottom of the conductive part abuts against the conical surface.

[0007] Preferably, the inner side of the lower connecting part is provided with an oil supply pipe and an oil cavity, one end of the oil supply pipe is connected to the oil cavity, and the oil cavity is arranged around the piston rod.

[0008] Preferably, both the upper connecting part and the lower connecting part are connected to a second sealing part. The second sealing part includes an outer connecting end and an inner connecting end. The outer connecting end is provided with a sealing ring, and the inner connecting end is provided with a retention part. The sealing ring and the retention part are arranged around the piston rod.

[0009] Preferably, the retention section includes a retention ring plate, and the retention ring plate has a retention cavity on the side near the piston rod.

[0010] Preferably, the end of the retention ring plate away from the piston rod is provided with a pressurization chamber, and a connecting hole is provided between the pressurization chamber and the retention chamber.

[0011] Preferably, the cross-sectional width of the connecting hole is smaller than the cross-sectional width of the retention cavity.

[0012] Preferably, at least two retention ring plates are provided on the top and bottom, and a scraping ring is provided between the retention ring plates.

[0013] Preferably, the scraping ring is a graphite ring.

[0014] Preferably, an expansion space is formed between the end of the scraping ring away from the piston rod and the retention ring plate, and the expansion space is connected to the pressurization chamber.

[0015] The present invention has the following beneficial effects;

[0016] 1. This design incorporates a compression section around the piston rod, with a certain gap between the compression section and the piston rod surface. Sealing oil is applied to the piston cylinder surface, and as the piston moves, the oil enters the gap between the compression section and the piston rod, forming a sealing oil film to prevent gas leakage. Simultaneously, the compression component squeezes the compression section, reducing the gap and making it less prone to gaps between the sealing oil film and the piston rod and compression section, resulting in a better seal. This design eliminates the need to replace or compensate for the seals, achieving superior sealing performance.

[0017] 2. The present invention also includes a retention section, which can form another oil film between the retention section and the piston rod, further enhancing the sealing performance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention;

[0019] Figure 2 This is a structural diagram of the second sealing part of the present invention;

[0020] Figure 3 for Figure 2 Enlarged structural diagram of the A mark in the middle;

[0021] Figure 4 This is a structural diagram of the retention cavity after sealing oil has been injected.

[0022] In the diagram: 1 Upper connecting part, 2 Middle part, 3 Lower connecting part, 4 Piston rod, 5 Extrusion part, 6 Spring, 7 Conducting part, 8 Cavity, 9 Conical surface, 10 Oil supply pipe, 11 Oil cavity, 12 External connecting end, 13 Embedded end, 14 Sealing ring, 15 Retention ring plate, 16 Retention cavity, 17 Pressurization cavity, 18 Connecting hole, 19 Scraping ring, 20 Expansion space. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0024] Example 1

[0025] An improved piston rod seal structure, such as Figure 1As shown, the device includes an upper connecting part 1, a middle part 2, a lower connecting part 3, a piston rod 4, and a first sealing part. The upper connecting part 1, the middle part 2, and the lower connecting part 3 are arranged sequentially, and the piston rod 4 passes through the upper connecting part 1, the middle part 2, and the lower connecting part 3 in sequence. The first sealing part includes an extrusion component, an extrusion section 5, and sealing oil. The extrusion section 5 surrounds the piston rod 4. The upper part of the upper connecting part 1 is the high-pressure side, and the lower part of the lower connecting part 3 is the low-pressure side. One end of the piston rod 4 is connected to a piston and reciprocates axially along the upper connecting part 1, the middle part 2, and the lower connecting part 3. The extrusion section 5 is located at the bottom of the middle part 2. The extrusion section 5 is a ring structure with a conical surface 9 at the top. The inner side of the middle part 2 is provided with a cavity 8. The top of the cavity 8 is connected to a spring 6. A conductive part 7 is also movably provided inside the cavity 8. The conductive part 7 is a hollow structure with an open top, and its external shape matches the cavity 8. The cavity 8 can be a cylindrical or square structure, and the external shape of the transmission part 7 is also a corresponding cylindrical or square structure. The bottom of the spring 6 acts on the transmission part, giving the transmission part 7 a downward force. The bottom of the transmission part 7 is in close contact with the extrusion part 5, and the upper cross section of the extrusion part 5 is a conical surface 9. The transmission part 7 transmits the force of the spring 6 to the extrusion part 5. Under the action of the conical surface 9 at the top of the extrusion part 5, the extrusion part 5 contracts towards the piston rod 4, thereby reducing the gap between the extrusion part 5 and the surface of the piston rod 4. In addition to the above structure, any structure that can cause the extrusion part 5 to contract can be used as an extrusion part. The lower connecting part 3 is provided with an oil supply pipe 10 and an oil cavity 11 on its inner side. One end of the oil supply pipe 10 is connected to the oil cavity 11. The oil cavity 11 is arranged around the piston rod 4. The oil supply pipe 10 can inject sealing oil into the oil cavity 11. The sealing oil can be lubricating oil, glycerin and olive oil. Many common lubricants on the market can be used as sealing oil in this embodiment. After the sealing oil is injected into the oil cavity 11, it will cover the surface of the piston rod 4 corresponding to the oil cavity 11. When the piston rod 4 moves from the low pressure side to the high pressure side, the sealing oil on the surface of the piston rod 4 will flow into the gap between the piston rod 4 and the extrusion part 5, and form a layer of sealing oil film in the gap as a sealing structure. The extrusion part extrudes the extrusion part 5, which can make the gap smaller. The sealing oil film is less likely to have gaps between the piston rod 4 and the extrusion part 5, and the sealing effect is better.

[0026] This solution requires neither replacing nor compensating for the seals, thus achieving a better sealing effect.

[0027] Example 2

[0028] This embodiment has the same parts as Embodiment 1, the difference being that: both the upper connecting part 1 and the lower connecting part 3 are connected to a second sealing part, and the second sealing parts connected to the upper connecting part 1 and the lower connecting part 3 are symmetrically arranged. Figure 2 and Figure 3This embodiment describes in detail the second sealing part connected to the upper connecting part 1. The second sealing part includes an outer connecting end 12 and an inner end 13. The outer connecting end 12 is provided with a sealing ring 14, and the inner end 13 is provided with a retention part. The sealing ring 14 and the retention part are arranged around the piston rod 4. The sealing ring 14 is provided to prevent sealing oil from leaking into the high-pressure side. The retention part can store the sealing oil. The retention part includes a retention ring plate 15. The retention ring plate 15 is provided with a retention cavity 16 on the side near the piston rod 4. When the piston rod 4 moves to the position of the sealing ring 14, its surface... The sealing oil is trapped by the sealing ring 14 and flows into the retention chamber 16. A pressure chamber 17 is provided at the end of the retention ring plate 15 away from the piston rod 4. A connecting hole 18 is provided between the pressure chamber 17 and the retention chamber 16. One function of the pressure chamber 17 is to clean the sealing oil in the retention chamber 16 after a long period of time by removing the sealing oil from the pressure chamber 17 through methods such as suction. Another important function of the pressure chamber 17 is to connect to a pressurizing device. When there is enough sealing oil in the retention chamber 16, such as... Figure 4 As shown, pressure is applied through the pressurizing chamber 17 to the sealing oil in the retention chamber 16, with the pressure direction as indicated by the arrow in the figure. At this time, the sealing oil in the retention chamber 16 will adhere tightly to the piston rod 4, providing another layer of sealing structure for the piston rod 4. This sealing structure, like the sealing oil film in Example 1, will not wear and has a good sealing effect. The cross-sectional width of the connecting hole 18 is smaller than the cross-sectional width of the retention chamber 16, the diameter of the connecting hole 18 is smaller, and the length of the connecting hole 18 is longer. After the pressurizing device pressurizes and maintains constant pressure, the process continues as follows... Figure 4 As shown, some sealing oil remains in the connecting hole 18. According to Pascal's law, a pressure change in a portion of a static fluid will be transmitted in all directions without change in magnitude. The pressure at the connecting hole 18 is P1, where P1 = F1 / S1, and F1 is the pressure applied to the surface of the sealing oil in the connecting hole 18 from the pressurizing chamber 17, and S1 is the area of ​​the sealing oil in the connecting hole 18 subjected to pressure. The pressure at the bottom of the retention chamber 16 is P2, where P2 = F2 / S2, where S2 is the area of ​​the sealing oil at the bottom of the retention chamber 16 acting on the surface of the piston rod 4. According to Pascal's law, P1=P2, so when S2 is much larger than S1, F2 will also be much larger than F1. F2 is the force exerted by the sealing oil at the bottom of the retention chamber 16 on the piston rod 4 and the cavity wall of the retention chamber 16. Due to the setting of the connecting hole 18, only a small force F1 is needed to make the sealing oil at the bottom of the retention chamber 16 exert a large force on the piston rod 4 and the cavity wall of the retention chamber 16. The purpose is to make the sealing oil adhere well to the piston rod 4 and the cavity wall, thereby improving the sealing effect.

[0029] Example 3

[0030] This embodiment adds a scraping ring 19 to the embodiments 1 and 2. The scraping ring 19 is located on one side of the retention chamber 16. There are at least two retention ring plates 15 on the top and bottom, and scraping rings 19 are provided between the retention ring plates 15. In this embodiment, there are three scraping rings 19, one between two retention ring plates 15 and the other two on the sides of the two retention ring plates 15 respectively. The purpose of the scraping ring 19 is to further trap the sealing oil of the piston rod 4 to prevent leakage. The scraping ring 19 is a graphite ring. When the graphite ring rubs against the piston rod 4, the graphite powder on its surface will remain on the surface of the piston rod 4, which plays a lubricating role. An expansion space 20 is formed between the end of the scraping ring 19 away from the piston rod 4 and the retention ring plate 15. The expansion space 20 is connected to the pressurization chamber 17. The pressurization device can provide pressure to the expansion space 20 so that the scraping ring 19 can be tightly attached to the piston rod 4.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An improved piston rod sealing structure, characterized in that: The device includes an upper connecting part (1), a middle part (2), a lower connecting part (3), a piston rod (4), and a first sealing part. The upper connecting part (1), the middle part (2), and the lower connecting part (3) are arranged sequentially, and the piston rod (4) passes through the upper connecting part (1), the middle part (2), and the lower connecting part (3) sequentially. The first sealing part includes an extruder, an extrusion part (5), and sealing oil. The extrusion part (5) surrounds the piston rod (4). The extruder presses the extrusion part (5) to shrink towards the piston rod (4). Sealing oil is provided between the extrusion part (5) and the circumferential surface of the piston rod (4). The upper connecting part (1) and the lower connecting part (3) are both connected to a second sealing part. The second sealing part includes an outer connecting end (12) and an inner sealing end (13). The outer connecting end (12) is provided with a sealing ring (14), and the inner sealing end (13) is provided with a sealing ring (14). The device is provided with a retention section. The sealing ring (14) and the retention section are arranged around the piston rod (4). The retention section includes a retention ring plate (15). The retention ring plate (15) is provided with a retention cavity (16) on the side of the retention ring plate (15) close to the piston rod (4). The end of the retention ring plate (15) away from the piston rod (4) is provided with a pressure cavity (17). A connecting hole (18) is provided between the pressure cavity (17) and the retention cavity (16). The cross-sectional width of the connecting hole (18) is smaller than the cross-sectional width of the retention cavity (16). There are at least two retention ring plates (15) on the top and bottom. A scraping ring (19) is provided between the retention ring plates (15). The scraping ring (19) is a graphite ring. An expansion space (20) is formed between the end of the scraping ring (19) away from the piston rod (4) and the retention ring plate (15). The expansion space (20) is connected to the pressure cavity (17).

2. The improved piston rod sealing structure according to claim 1, characterized in that: The extrusion component includes a spring (6) and a conductive part (7). The inner side of the middle part (2) is provided with a cavity (8). The spring (6) is sleeved on the piston rod (4) and the top of the spring (6) is connected to the top of the cavity (8). The bottom of the spring (6) abuts against the conductive part (7). The extrusion part (5) is located below the conductive part (7) and a conical surface (9) is provided above the extrusion part (5). The bottom of the conductive part (7) abuts against the conical surface (9).

3. The improved piston rod sealing structure according to claim 2, characterized in that: The lower connecting part (3) is provided with an oil supply pipe (10) and an oil chamber (11) on its inner side. One end of the oil supply pipe (10) is connected to the oil chamber (11), and the oil chamber (11) is arranged around the piston rod (4).

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