A hydraulic cylinder internal leakage detection device and detection method

Abstract

The application provides a hydraulic cylinder inner leakage detection device and method, and relates to the technical field of hydraulic cylinders.The device comprises a seat body, which is fixed to one end inside the hydraulic cylinder and can be used for limiting the piston inside the hydraulic cylinder; a concave cavity is arranged in the center of the seat body; an annular groove coaxial with the concave cavity is further arranged on the seat body; the annular groove and the concave cavity are arranged on the seat body close to one end of the piston; an annular groove and an oil inlet and outlet are further arranged on the seat body; the oil inlet and outlet is communicated with an oil injection port of the hydraulic cylinder; the annular groove is communicated with the oil inlet and outlet; and the annular groove is communicated with the inner cavity of the end of the hydraulic cylinder. When inner leakage detection is needed, the first ring body and the second ring body are used for cooperating with the piston to perform detection, without any disassembly of the hydraulic cylinder, and the position of the inner leakage, whether between the piston and the cylinder rod or between the piston and the cylinder wall, can be directly detected.

Description

Technical Field

[0001] This invention relates to the technical field of hydraulic cylinders, and more particularly to a device and method for detecting internal leakage in hydraulic cylinders. Background Technology

[0002] A hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy, performing linear reciprocating motion or oscillating motion. Due to its simple structure and reliable operation, hydraulic cylinders have been widely used in the hydraulic systems of various machines.

[0003] Hydraulic cylinder leaks can occur due to manufacturing defects or aging from prolonged use. Hydraulic oil leaks are classified into internal and external leaks. External leaks are easily observable from the outside and are readily detectable. Internal leaks, however, occur when hydraulic oil abnormally flows from the high-pressure chamber inside the cylinder, through gaps in the piston-cylinder joint and the piston rod-seal joint, into the low-pressure chamber. Internal leaks cause a decrease in hydraulic rod thrust, slower movement, and reduced load, leading to instability in the hydraulic rod's support. Unlike external leaks, internal leaks are not easily observed because the entire process occurs inside the cylinder body, making detection more difficult.

[0004] Currently, there are three commonly used methods for testing hydraulic cylinders:

[0005] 1. Pressure holding-sinking method (most commonly used on site)

[0006] Extend the hydraulic cylinder to half or full extension to support the rated load, then close all hydraulic valves and stop the machine. If the piston rod shows visible "retraction" or the load "sinks" within 10–30 minutes, there is an internal leak. Measure the retraction amount ΔL with a ruler, and estimate the leak volume using ΔV = A × ΔL. This method requires no instruments and is suitable for quick on-site assessment.

[0007] 2. Static pressure holding test to measure pressure drop (laboratory or workshop)

[0008] After pressurizing the working chamber to the rated pressure, close the oil port and record the pressure drop value Δp over 5–10 minutes using a high-precision pressure sensor. Calculate the leakage flow rate using the formula q = V × Δp / (E × t) (where V is the chamber volume and E is the elastic modulus of the oil). An internal leakage is diagnosed if the pressure drop rate exceeds the standard.

[0009] 3. Flow-displacement method (bench quantitative test)

[0010] On a dedicated test bench, one chamber of the test cylinder is locked, while the other chamber continues to supply oil and maintain a constant pressure. The piston's "crawling" distance S per minute is measured using a grating ruler or displacement sensor, and the leakage amount (ml / min) is directly obtained by q = A × S, which has high accuracy.

[0011] The first detection method can be performed without disassembling the machine, but the detection accuracy is low, and it cannot determine whether the sinking is caused by internal leakage or leakage in the pipeline connected to the hydraulic cylinder. The latter two methods are difficult to operate in the field and require disassembly. Furthermore, all three methods can only determine whether internal leakage has occurred, but cannot determine whether the internal leakage is at the piston and cylinder or at the piston rod and piston. Further confirmation of the specific leakage location is required during subsequent maintenance. Summary of the Invention

[0012] In view of the shortcomings of the prior art, the purpose of this invention is to provide a hydraulic cylinder internal leakage detection device and detection method, which can solve the technical problems of complex internal leakage detection operation and inability to detect specific leakage locations in the prior art.

[0013] In a first aspect, a hydraulic cylinder internal leakage detection device is provided, comprising a base fixed to one end inside the hydraulic cylinder, which can be used to limit the piston inside the hydraulic cylinder.

[0014] The seat body has a recessed cavity at its center, and the seat body also has an annular groove coaxially arranged with the recessed cavity. The annular groove and the recessed cavity are located at one end of the seat body near the piston.

[0015] The seat body is also provided with an annular groove and an oil inlet and outlet. The oil inlet and outlet are connected to an oil filling port of the hydraulic cylinder. The annular groove is connected to the oil inlet and outlet and is connected to the inner cavity of that end of the hydraulic cylinder.

[0016] The seat body has a first ring and a second ring on the side facing the piston. The ring groove is provided between the first ring and the second ring. A second sealing ring is fixed on the first ring and a first sealing ring is fixed on the second ring. A leakage detection device is provided on the first ring in the area outside the second sealing ring, and a leakage detection device is also provided on the second ring in the area inside the first sealing ring.

[0017] The outer side of the first ring body is provided with several sealing ring mounting grooves, and a third sealing ring is fixed in each of the sealing ring mounting grooves. The sealing ring mounting grooves and the third sealing rings further form a seal between the first ring body and the cylinder wall.

[0018] As a further embodiment of the present invention, the leakage detection device includes a detection hole, a detection column and a spring. One end of the detection hole is connected to the side of the seat near the piston, and the other end of the detection hole is connected to the annular groove. The detection column is slidably disposed in the detection hole, and the spring is provided at the end of the detection column away from the piston. The spring pushes the detection column to move towards the end near the piston.

[0019] As a further embodiment of the present invention, a retaining ring is fixed on the detection column, the retaining ring is in contact with one end of the spring, and the diameter of the detection column is 1 to 3 millimeters.

[0020] As a further embodiment of the present invention, a fourth sealing ring and a sealing ring fixing ring are provided on the side of the retaining ring away from the spring. The sealing ring fixing ring is fixedly engaged with the inner wall of the detection hole. An annular groove is formed in the sealing ring fixing ring, and the fourth sealing ring is fixedly disposed in the annular groove. The fourth sealing ring is in contact with the detection column.

[0021] As a further embodiment of the present invention, it also includes an RFID component, which includes an RFID tag, a push switch, and an encapsulation film. The RFID tag and the push switch are integrated within the encapsulation film. The push switch is a pass switch for the RFID tag and is fixed to the end of the detection hole away from the detection post.

[0022] As a further embodiment of the present invention, a label receiving pit is provided at one end of the seat away from the cavity, and a communicating groove is provided between the label receiving pit and the detection hole.

[0023] As a further embodiment of the present invention, a limiting mechanism is also included, which includes a limiting post, a pressing post, and a limiting ring. The limiting post is fixed to the end of the retaining ring away from the detection post, the pressing post is fixed to the end of the limiting post away from the retaining ring, and the limiting ring is fixed to the end port of the detection hole away from the detection post. The spring is connected between the limiting ring and the retaining ring. A through hole is opened in the limiting ring, the diameter of which is larger than the diameter of the pressing post and smaller than the diameter of the limiting post.

[0024] A second aspect of the present invention provides a method for detecting internal leakage in a hydraulic cylinder, comprising the following detection process:

[0025] S1. Inject hydraulic oil into the end of the hydraulic cylinder without a seat, so that the piston in the hydraulic cylinder is in close contact with the first ring and the second ring, and then close each valve body after applying pressure for 1 second.

[0026] S2. Check the position of the detection columns inside the two leak detection devices at time points of 1 minute, 2 minutes, 5 minutes, 10 minutes, and 15 minutes;

[0027] S3. Confirm whether the detection columns in both leak detection devices have moved. If neither detection column in one leak detection device has moved, then there is no leak. If only the detection column in one leak detection device has moved, the location of the leak detection device can be used to determine whether the internal leak is between the piston and cylinder rod or between the piston and cylinder wall, thus facilitating subsequent targeted maintenance. If the detection columns in both leak detection devices have moved, then there is a leak between the piston and cylinder rod and between the piston and cylinder wall.

[0028] A third aspect of the present invention provides a method for detecting internal leakage in a hydraulic cylinder, comprising the following detection process:

[0029] S1. Fix the RFID tag reading and writing device near the seat, inject hydraulic oil into the end of the hydraulic cylinder without the seat, so that the piston in the hydraulic cylinder is in close contact with the first ring and the second ring, and then close each valve body after further pressurization for 1 second.

[0030] S2. After closing the valve body, start timing. The maximum timing time is 15 minutes. Wait for the RFID tag reader / writer to respond.

[0031] S3. If the RFID tag reader responds within 15 minutes, record the time of the response and use the information from the RFID tag to determine the location of the internal leak.

[0032] S4. Calculate the leakage rate based on the response time of the RFID tag reader / writer and determine whether the leakage rate is compliant.

[0033] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0034] This invention arranges the seat inside the hydraulic cylinder without affecting its normal operation. When internal leakage detection is required, the first and second rings cooperate with the piston for detection without disassembling the hydraulic cylinder. It can also directly detect whether the internal leakage occurs between the piston and cylinder rod, between the piston and cylinder wall, or both, thus more accurately detecting the specific leakage situation. Attached Figure Description

[0035] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the present invention when it is installed and assembled with a hydraulic cylinder.

[0037] Figure 2 Provided for embodiments of the present invention Figure 1 Enlarged view of point A in the middle.

[0038] Figure 3 This is a three-dimensional structural diagram provided for an embodiment of the present invention.

[0039] Figure 4 For the embodiments of the present invention and Figure 3 A schematic diagram of a three-dimensional structure in the opposite direction.

[0040] Figure 5 This is a front view of an embodiment of the present invention.

[0041] Figure 6 Provided for embodiments of the present invention Figure 5 Sectional view at point BB.

[0042] Figure 7 Provided for embodiments of the present invention Figure 6 Enlarged view of point C in the middle.

[0043] Figure 8 This is a schematic diagram of the structure of an RFID tag provided in an embodiment of the present invention.

[0044] Explanation of reference numerals in the attached drawings: 1-base body, 101-first ring body, 102-second ring body, 2-cavity, 3-tag receiving pit, 4-third sealing ring, 5-first sealing ring, 6-second sealing ring, 7-detection column, 8-oil inlet / outlet, 9-ring groove, 10-connecting hole, 11-connecting groove, 12-rotation limiting ring, 13-sealing ring mounting groove, 14-detection hole, 15-fourth sealing ring, 16-sealing ring fixing ring, 17-retaining ring, 18-limiting column, 19-pressing column, 20-spring, 21-limiting ring, 22-encapsulation film, 23-RFID tag, 24-press switch. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0046] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.

[0047] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention.

[0048] Example 1, as Figures 1 to 8 As shown, a hydraulic cylinder internal leakage detection device includes: a base 1, which is fixed to one end inside the hydraulic cylinder and can be used to limit the piston inside the hydraulic cylinder;

[0049] The seat body 1 has a cavity 2 at its center, and the seat body 1 also has an annular groove 9 coaxially arranged with the cavity 2. The annular groove 9 and the cavity 2 are located on the seat body 1 at one end near the piston.

[0050] The seat 1 is also provided with an annular groove 9 and an oil inlet / outlet 8. The oil inlet / outlet 8 is connected to an oil filling port of the hydraulic cylinder. The annular groove 9 is connected to the oil inlet / outlet 8 and the annular groove 9 is connected to the inner cavity of that end of the hydraulic cylinder. The seat 1 as a whole is used to limit the piston and prevent the piston from moving to the position area that blocks the oil filling port. The seat 1 is positioned and installed by the rotation limiting ring 12 between the oil inlet / outlet 8 and the oil filling port.

[0051] The seat 1 has a first ring 101 and a second ring 102 on the side facing the piston. The ring groove 9 is provided between the first ring 101 and the second ring 102. A second sealing ring 6 is fixed on the first ring 101 and a first sealing ring 5 is fixed on the second ring 102. A leakage detection device is provided on the first ring 101 in the area outside the second sealing ring 6, and a leakage detection device is also provided on the second ring 102 in the area inside the first sealing ring 5.

[0052] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0053] In this embodiment of the invention, the seat 1 is divided into two regions, a first ring 101 and a second ring 102, by an annular groove 9. A second sealing ring 6 is set on the first ring 101, and a first sealing ring 5 is set on the second ring 102. When the piston moves to abut against the seat 1, both the first sealing ring 5 and the second sealing ring 6 abut against the piston, forming two non-interconnected sealing areas. The sealing area inside the first sealing ring 5 is connected to the mating area between the piston and the cylinder rod, and the sealing area outside the second sealing ring 6 is connected to the mating area between the piston and the cylinder wall. Thus, by setting a leakage detection device in the two sealing areas, it is possible to clearly detect whether internal leakage has occurred in the hydraulic cylinder, and further determine whether the internal leakage occurs between the piston and the cylinder rod, between the piston and the cylinder wall, or both, so as to more accurately detect the specific leakage situation.

[0054] In one possible implementation, a plurality of sealing ring mounting grooves 13 are provided on the outer side of the first ring body 101, and a third sealing ring 4 is fixed in each of the sealing ring mounting grooves 13. The sealing ring mounting grooves 13 and the third sealing rings 4 further form a seal between the first ring body 101 and the cylinder wall, thereby ensuring the sealing effect of the sealing area outside the second sealing ring 6.

[0055] In this embodiment of the invention, the multi-layer sealing structure forms a redundant sealing barrier. Even if the main sealing ring is worn, the third sealing ring 4 can still temporarily withstand pressure, thus achieving a fail-safe design.

[0056] In one possible implementation, the leakage detection device includes a detection hole 14, a detection post 7, and a spring 20. One end of the detection hole 14 is connected to the side of the seat 1 near the piston, and the other end of the detection hole 14 is connected to the annular groove 9. The detection post 7 is slidably disposed in the detection hole 14, and the spring 20 is provided at the end of the detection post 7 away from the piston. The spring 20 pushes the detection post 7 to move towards the end closer to the piston.

[0057] In this embodiment of the invention, after the piston contacts the seat 1, if internal leakage occurs, the hydraulic oil leaking from the high-pressure chamber enters the detection hole 14, pushing the detection column 7 inside the detection hole 14 to slide. Under the pressure of the hydraulic oil, the detection column 7 overcomes the elastic force of the spring 20 and moves, thereby causing a significant change in the position of the detection column 7. The position of the detection column 7 is confirmed to have changed by non-destructive testing equipment such as ultrasonic waves outside the hydraulic cylinder, thus confirming whether oil leakage has occurred. There is no need to disassemble the hydraulic cylinder, making the detection process convenient.

[0058] In one possible implementation, a retaining ring 17 is fixed on the detection post 7, the retaining ring 17 is in contact with one end of the spring 20, and the diameter of the detection post 7 is 1 to 3 millimeters.

[0059] In this embodiment of the invention, the retaining ring 17 ensures full contact with the spring 20, allowing the spring 20 to smoothly push the detection column 7 while reducing the diameter of the detection column 7. Thus, only a very small amount of hydraulic oil leakage is needed to push the detection column 7 to a large displacement. The retaining ring 17 has a cross-section design that is much larger than that of the detection column 7, making it easier for the detection equipment to detect and detect whether the detection column 7 has changed position, thereby enabling more accurate detection of internal leakage.

[0060] In one possible implementation, the retaining ring 17 is provided with a fourth sealing ring 15 and a sealing ring fixing ring 16 on the side away from the spring 20. The sealing ring fixing ring 16 is fixedly engaged with the inner wall of the detection hole 14. An annular groove is provided in the sealing ring fixing ring 16, and the fourth sealing ring 15 is fixedly disposed in the annular groove. The fourth sealing ring 15 is in contact with the detection post 7.

[0061] In this embodiment of the invention, the sealing performance of the detection column 7 is ensured, preventing the oil from leaking from the gap between the detection column 7 and the detection hole 14 and thus preventing the detection column 7 from moving. The fourth sealing ring 15 forms a dynamic sealing barrier, ensuring the free sliding of the detection column 7 while preventing bypass leakage, ensuring that the oil pressure is fully applied to the detection column 7, and improving the reliability of the detection. The modular design of the fixing ring supports quick replacement of the seals.

[0062] In one possible implementation, an RFID component is also included, comprising an RFID tag 23, a push-button switch 24, and an encapsulation film 22. The RFID tag 23 and the push-button switch 24 are integrated within the encapsulation film 22, which protects the RFID tag 23 and the push-button switch 24 from damage caused by immersion in oil. The push-button switch 24 serves as a pass switch for the RFID tag 23 and is fixed to the end of the detection hole 14 away from the detection post 7. Movement of the detection post 7 can press the push-button switch 24, thereby creating a pass through the entire RFID component. The movement of the detection post 7 can be quickly determined by detecting the movement of the RFID tag 7 using an RFID tag reader / writer outside the hydraulic cylinder.

[0063] In this embodiment of the invention, the movement of the detection column 7 triggers the press switch 24, so that the tag signal is quickly detected by the RFID tag reading and writing device after the press switch 24 is in operation. Based on the volume change in the detection hole 14 caused by the movement of the detection column 7 and the movement time of the detection column 7, not only can internal leakage be detected, but the rate of internal leakage can also be determined, and the internal leakage situation can be measured more accurately. At the same time, internal leakage detection can be completed without any disassembly of the device.

[0064] In one possible implementation, a tag receiving pit 3 is provided at one end of the base 1 away from the cavity 2. A connecting groove 11 is provided between the tag receiving pit 3 and the detection hole 14. The push switch 24 in the RFID component is a separate extended section. The connecting groove 11 can facilitate the accommodation of the extended part of the RFID component. Multiple RFID tags 23 can be installed and fixed in the tag receiving pit 3. The connecting groove 11 is connected to the annular groove 9 through a connecting hole 10, thereby achieving the effect that the other end of the detection hole 14 is connected to the annular groove 9.

[0065] In one possible implementation, the push-button switch 24 is at risk of being damaged by the strong hydraulic pressure exerted on the detection post 7. Therefore, a limiting mechanism is designed for the detection post 7, comprising a limiting post 18, a pressing post 19, and a limiting ring 21. The limiting post 18 is fixed to the end of the retaining ring 17 away from the detection post 7, the pressing post 19 is fixed to the end of the limiting post 18 away from the retaining ring 17, and the limiting ring 21 is fixed within the detection hole 14 at the end port away from the detection post 7. A spring 20 is connected between the limiting ring 21 and the retaining ring 17. A through hole is formed within the limiting ring 21, the diameter of which is larger than the diameter of the pressing post 19 but smaller than the diameter of the limiting post 18.

[0066] In this embodiment of the invention, the pressing post 19 can pass through the limiting ring 21 to press the push switch 24. The cooperation between the limiting post 18 and the limiting ring 21 restricts the extension length of the pressing post 19, so that the pressing post 19 can only extend to the length to press the push switch 24, and will not press the push switch 24 excessively, thus preventing damage to the push switch 24.

[0067] Example 2: Based on Example 1, this example further provides a method for detecting internal leakage in a hydraulic cylinder, including the following detection steps:

[0068] S1. Inject hydraulic oil into the end of the hydraulic cylinder without the seat 1, so that the piston in the hydraulic cylinder is in close contact with the first ring 101 and the second ring 102. After pressurizing for 1 second, close each valve body. From the outside of the hydraulic cylinder, it can be seen that the hydraulic cylinder is shortened to its shortest state, and then pressurized for 1 second.

[0069] S2. Check the position of the detection column 7 inside the two leakage detection devices at time points of 1 minute, 2 minutes, 5 minutes, 10 minutes, and 15 minutes;

[0070] S3. Confirm whether the detection column 7 in both leak detection devices has moved. If the detection column 7 in one leak detection device has not moved, there is no leak. If the detection column 7 in only one leak detection device has moved, the location of the leak detection device can be used to determine whether the internal leak is between the piston and cylinder rod or between the piston and cylinder wall, which facilitates subsequent targeted maintenance. If the detection column 7 in both leak detection devices has moved, there is a leak between the piston and cylinder rod and between the piston and cylinder wall.

[0071] Example 3, based on Example 1, further provides a method for detecting internal leakage in hydraulic cylinders, which further utilizes RFID tags to complete the internal leakage detection, including the following detection steps:

[0072] S1. Fix the RFID tag reading and writing device near the seat 1, inject hydraulic oil into the end of the hydraulic cylinder without the seat 1, so that the piston in the hydraulic cylinder is in close contact with the first ring 101 and the second ring 102, pressurize for 1 second and then close each valve body. From the outside of the hydraulic cylinder, this is the process of the hydraulic cylinder shortening to its shortest state, and then pressurize for 1 second.

[0073] S2. After closing the valve body, start timing. The maximum timing time is 15 minutes. Wait for the RFID tag reader / writer to respond.

[0074] S3. If the RFID tag reader responds within 15 minutes, record the time of the response and use the information from RFID tag 23 to determine the location of the internal leak.

[0075] S4. Calculate the leakage rate based on the response time of the RFID tag reader / writer and determine whether the leakage rate is compliant.

[0076] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A hydraulic cylinder internal leakage detection device, characterized in that, include: A seat body, which is fixed to one end inside the hydraulic cylinder, can be used to limit the piston inside the hydraulic cylinder; The seat body has a recessed cavity at its center, and the seat body also has an annular groove coaxially arranged with the recessed cavity. The annular groove and the recessed cavity are located at one end of the seat body near the piston. The seat body is also provided with an annular groove and an oil inlet and outlet. The oil inlet and outlet are connected to an oil filling port of the hydraulic cylinder. The annular groove is connected to the oil inlet and outlet and is connected to the inner cavity of that end of the hydraulic cylinder. The seat body has a first ring and a second ring on the side facing the piston. The ring groove is provided between the first ring and the second ring. A second sealing ring is fixed on the first ring and a first sealing ring is fixed on the second ring. A leakage detection device is provided on the first ring in the area outside the second sealing ring, and a leakage detection device is also provided on the second ring in the area inside the first sealing ring.

2. The hydraulic cylinder internal leakage detection device according to claim 1, characterized in that, The outer side of the first ring body is provided with several sealing ring mounting grooves, and a third sealing ring is fixed in each of the sealing ring mounting grooves. The sealing ring mounting grooves and the third sealing rings further form a seal between the first ring body and the cylinder wall.

3. The hydraulic cylinder internal leakage detection device according to claim 1, characterized in that, The leakage detection device includes a detection hole, a detection column, and a spring. One end of the detection hole is connected to the side of the seat near the piston, and the other end of the detection hole is connected to the annular groove. The detection column is slidably disposed in the detection hole. The spring is provided at the end of the detection column away from the piston, and the spring pushes the detection column to move towards the end closer to the piston.

4. The hydraulic cylinder internal leakage detection device according to claim 3, characterized in that, A retaining ring is fixed on the detection column, and the retaining ring contacts one end of the spring. The diameter of the detection column is 1 to 3 millimeters.

5. The hydraulic cylinder internal leakage detection device according to claim 4, characterized in that, The retaining ring is provided with a fourth sealing ring and a sealing ring fixing ring on the side away from the spring. The sealing ring fixing ring is fixedly fitted with the inner wall of the detection hole. An annular groove is opened in the sealing ring fixing ring, and the fourth sealing ring is fixedly installed in the annular groove. The fourth sealing ring is in contact with the detection column.

6. The hydraulic cylinder internal leakage detection device according to claim 3, characterized in that, It also includes an RFID component, which includes an RFID tag, a push-button switch, and an encapsulation film. The RFID tag and the push-button switch are integrated into the encapsulation film. The push-button switch is the access switch for the RFID tag and is fixed to the end of the detection hole away from the detection post.

7. A hydraulic cylinder internal leakage detection device according to claim 6, characterized in that, A label receiving pit is provided at one end of the base away from the cavity, and a connecting groove is provided between the label receiving pit and the detection hole.

8. The hydraulic cylinder internal leakage detection device according to claim 4, characterized in that, It also includes a limiting mechanism, which includes a limiting post, a pressing post, and a limiting ring. The limiting post is fixed to the end of the retaining ring away from the detection post. The pressing post is fixed to the end of the limiting post away from the retaining ring. The limiting ring is fixed inside the detection hole at the end port away from the detection post. The spring is connected between the limiting ring and the retaining ring. A through hole is opened in the limiting ring. The diameter of the through hole is larger than the diameter of the pressing post and smaller than the diameter of the limiting post.

9. The detection method of the hydraulic cylinder internal leakage detection device according to any one of claims 1-8, characterized in that, The testing process includes the following: S1. Inject hydraulic oil into the end of the hydraulic cylinder without a seat, so that the piston in the hydraulic cylinder is in close contact with the first and second rings, and then close each valve body after applying pressure for 1 second. S2. Check the position of the detection columns inside the two leak detection devices at time points of 1 minute, 2 minutes, 5 minutes, 10 minutes, and 15 minutes; S3. Confirm whether the detection columns in both leak detection devices have moved. If the detection columns in both leak detection devices have not moved, there is no leak. If the detection column in only one leak detection device has moved, the position of the moved detection column can be used to determine whether the internal leak is between the piston and cylinder rod or between the piston and cylinder wall, which facilitates subsequent targeted maintenance. If the detection columns in both leak detection devices have moved, there is a leak between the piston and cylinder rod and between the piston and cylinder wall.

10. The detection method of the hydraulic cylinder internal leakage detection device according to claim 6, characterized in that, The testing process includes the following: S1. Fix the RFID tag reading and writing device near the seat, inject hydraulic oil into the end of the hydraulic cylinder without the seat, so that the piston in the hydraulic cylinder is in close contact with the first ring and the second ring, and then close each valve body after further pressurization for 1 second. S2. After closing the valve body, start timing. The maximum timing time is 15 minutes. Wait for the RFID tag reader / writer to respond. S3. If the RFID tag reader responds within 15 minutes, record the time of the response and use the information from the RFID tag to determine the location of the internal leak. S4. Calculate the leakage rate based on the response time of the RFID tag reader / writer and determine whether the leakage rate is compliant.

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