Seal life monitoring method and system for a variable amplitude cylinder

Abstract

The present application belongs to the technical field of working machines, and particularly relates to a sealing element life monitoring method and system for a luffing oil cylinder. The sealing element life monitoring method comprises: obtaining a leakage settlement displacement amount of the luffing oil cylinder in a static time period when the luffing oil cylinder is static in a detection posture; determining a settlement displacement amount early warning value corresponding to the static time period; and determining that the sealing element of the luffing oil cylinder needs to be replaced in the case that the leakage settlement displacement amount is greater than the settlement displacement amount early warning value. The sealing element life monitoring method can determine whether the sealing element life reaches the replacement standard according to the leakage settlement displacement amount, so that the sealing element can be replaced in time to reduce the safety hazards caused by sealing element failure.

Description

Technical Field

[0001] This invention belongs to the field of operational machinery technology, specifically relating to a method and system for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder. Background Technology

[0002] For luffing tower cranes using hydraulic cylinders for luffing, the luffing motion of the jib is driven by the luffing cylinder. Regardless of whether the crane is in operation or stopped, the load on the jib is directly borne and supported by the luffing cylinder; therefore, the reliability of the luffing cylinder directly determines the overall safety performance of the tower crane. Currently, some luffing tower cranes are equipped with mechanical locking devices to lock the jib position and prevent displacement when the crane is stopped for extended periods. However, locking and unlocking these mechanical locking devices generally require multiple operators, while in actual operation, only one operator is typically on the crane's control side. A single person cannot independently perform the locking operation, resulting in a low utilization rate of these devices in practical applications. If the jib is not limited by the mechanical locking device when the crane is stopped, and the luffing cylinder fails, the jib is prone to downward displacement, posing a risk of colliding with surrounding buildings and causing a safety accident.

[0003] Furthermore, luffing cylinders typically contain multiple seals, such as piston seals, piston rod seals, and balance valve seals at the cylinder's inlet and outlet. These seals are all consumable components with a limited service life. As the luffing cylinder operates over time, the wear on these seals gradually increases, eventually leading to significant internal or external leakage due to seal failure. This prevents the luffing cylinder from performing luffing operations correctly. If the tower crane malfunctions during lifting operations due to excessive leakage from the cylinder, on-site repairs will be difficult, and downtime will be prolonged. This will not only severely delay construction progress but also further increase operational safety risks. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for monitoring the lifespan of the seals of a luffing cylinder, so as to promptly determine when the lifespan of the seals of the luffing cylinder is about to end, and prevent seal failure from affecting the operation of the luffing tower crane.

[0005] To achieve the above objectives, the present invention provides a method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder, the method comprising: When the luffing cylinder is stationary in the detection posture, the leakage settlement displacement of the luffing cylinder during the stationary period is obtained; Determine the early warning value of settlement displacement corresponding to the static time period; If the leakage settlement displacement exceeds the warning value, it is determined that the seals of the luffing cylinder need to be replaced.

[0006] In some implementations, determining the settlement displacement warning value corresponding to the static time period further includes: establishing a correspondence between the static time interval of the variable amplitude cylinder and the settlement displacement warning value; determining the static time interval corresponding to the static time period; and determining the settlement displacement warning value corresponding to the static time period based on the correspondence.

[0007] In some implementations, the first and last times corresponding to the static time period are the first moment and the second moment, respectively. Obtaining the leakage settlement displacement of the luffing cylinder during the static time period includes: determining the first displacement of the luffing cylinder at the first moment and the second displacement at the second moment; and obtaining the settlement displacement of the luffing cylinder during the static time period based on the difference between the first displacement and the second displacement.

[0008] In some implementations, the luffing cylinder is applied to a luffing tower crane. The luffing cylinder is used to drive the boom to luff. Determining the first displacement and the second displacement of the luffing cylinder at a first moment and at a second moment includes: acquiring the first tilt angle of the boom at the first moment; acquiring the second tilt angle of the boom at the second moment; determining the first displacement based on the first tilt angle and determining the second displacement based on the second tilt angle; or, determining the first displacement and the second displacement based on the signal transmitted by the displacement sensor on the luffing cylinder.

[0009] In some embodiments, the seal life monitoring method further includes: uploading a first moment, a first tilt angle, a second moment, and a second tilt angle to a remote monitoring platform; the remote monitoring platform determines the leakage settlement displacement based on the first moment, the first tilt angle, the second moment, and the second tilt angle; and when the leakage settlement displacement exceeds a settlement displacement warning value, the remote monitoring platform issues a life warning signal.

[0010] In some embodiments, the first and last times of the static time period are the first moment and the second moment, respectively. Obtaining the leakage settlement displacement of the luffing cylinder during the static time period includes: obtaining the first hydraulic oil temperature and the second hydraulic oil temperature of the luffing cylinder at the first moment and the second moment; obtaining the first displacement at the first moment and the total settlement displacement of the luffing cylinder at the second moment; determining the temperature displacement of the luffing cylinder affected by temperature based on the first hydraulic oil temperature, the second hydraulic oil temperature and the first displacement; and determining the leakage settlement displacement of the luffing cylinder based on the difference between the total settlement displacement and the temperature displacement.

[0011] In some implementations, the temperature displacement is determined according to the following formula: (1) in, This is the temperature displacement. The coefficient of thermal expansion of hydraulic oil. This is the difference between the temperature of the first hydraulic oil and the temperature of the second hydraulic oil. This is the first displacement.

[0012] In some implementations, the seal life monitoring method further includes: recording the extension and retraction stroke of the luffing cylinder in real time during luffing operation; and determining that the seal of the luffing cylinder needs to be replaced if the cumulative stroke of the luffing cylinder exceeds the set stroke.

[0013] In some embodiments, the seal life monitoring method further includes: issuing a warning when it is determined that the seal of the luffing cylinder needs to be replaced; and inspecting the luffing cylinder according to the warning to determine the seal that needs to be replaced.

[0014] A second aspect of the present invention provides a sealing component life monitoring system for a luffing cylinder. The sealing component life monitoring system includes: a displacement monitoring unit for acquiring the leakage settlement displacement of the luffing cylinder during a static period; a life determination unit for determining a settlement displacement warning value corresponding to the static period, and determining that the sealing component of the luffing cylinder needs to be replaced if the leakage settlement displacement exceeds the settlement displacement warning value; and an alarm unit for issuing an alarm prompt when it is determined that the sealing component needs to be replaced.

[0015] The above technical solution provides a method for monitoring the lifespan of seals in a luffing cylinder. This method includes: acquiring the leakage and settlement displacement of the luffing cylinder during a stationary period when the cylinder is in a detection posture; determining a warning value for the settlement displacement corresponding to the stationary period; and determining that the seals of the luffing cylinder need to be replaced if the leakage and settlement displacement exceeds the warning value. This method allows for the acquisition of the leakage and settlement displacement of the luffing cylinder during a stationary period. Based on the magnitude of this leakage and settlement displacement, it is possible to determine whether the seals have reached the replacement threshold, thereby preventing safety accidents caused by the impending end of seal life.

[0016] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. Those skilled in the art can obtain other drawings based on the structures shown in these drawings without any inventive effort. In the drawings: Figure 1 A flowchart of a method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating an application scenario of the variable amplitude hydraulic cylinder provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures 10 counterweight arms 20-ton crane boom 30 luffing hydraulic cylinder Detailed Implementation The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0019] The following description, with reference to the accompanying drawings, illustrates a method and system for monitoring the seal life of the variable-amplitude cylinder 30 according to the present invention. Figure 1 The diagram shows a flowchart of a method for monitoring the lifespan of the seals of a luffing cylinder 30 according to an embodiment of the present invention. The method for monitoring the lifespan of the seals of the luffing cylinder 30 includes: S101, when the luffing cylinder 30 is stationary in the detection posture, obtain the leakage settlement displacement of the luffing cylinder 30 during the stationary period. S102, determine the early warning value of settlement displacement corresponding to the static time period; S103, if the leakage settlement displacement exceeds the warning value of settlement displacement, it is determined that the seal of the variable amplitude cylinder 30 needs to be replaced.

[0020] In the existing technology, it is difficult to monitor and determine the life of the seals of the luffing cylinder 30. They can only be inspected and replaced when the luffing cylinder 30 cannot lift or lower normally. However, the luffing tower crane usually has its boom suspended for a long time during the stationary period. If the seals fail, the boom 20 will fall naturally, which may cause the boom to collide with the building.

[0021] The sealing life monitoring method provided in this invention can acquire the leakage settlement displacement of the luffing cylinder 30 during a static period while the cylinder 30 remains in a detection posture. Based on this leakage settlement displacement, it can determine whether excessive settlement has occurred due to leakage. If the leakage settlement displacement exceeds the corresponding warning value, it can be determined that the sealing life of the luffing cylinder 30 is nearing its end, requiring immediate replacement. The detection posture of the luffing cylinder 30 refers to the posture where the piston rod extends out of the cylinder body, allowing the hydraulic oil in the rodless chamber to withstand a certain boom pressure. The static period refers to the time between the start of static posture and the receipt of a command action.

[0022] By using the above-mentioned method for monitoring the life of seals, the leakage and settlement displacement of the variable amplitude cylinder 30 can be determined more accurately, thereby determining whether the life of the seals has reached the standard for replacement and reducing safety hazards caused by seal wear and failure.

[0023] In one specific embodiment, the static time period must exceed a preset time period. The preset time period is the minimum static duration set to facilitate monitoring of leakage displacement settlement of the luffing cylinder 30, and is typically determined based on a comprehensive consideration of factors such as the equipment model, historical leakage data, and the characteristics of the sealing material. If the static time period is too short, the leakage settlement displacement obtained from the test will be inaccurate, and the test results will not be of reference value.

[0024] In one embodiment, determining the settlement displacement warning value corresponding to the static time period further includes: establishing a correspondence between the static time interval of the variable amplitude cylinder 30 and the settlement displacement warning value; determining the static time interval corresponding to the static time period; and determining the settlement displacement warning value corresponding to the static time period based on the correspondence. This correspondence can be preset based on experimental test results to ensure the rationality and adaptability of the warning threshold under different static time periods. For example, the longer the static time, the more lenient the allowable settlement displacement can be, but it must be controlled within a safe range to avoid misjudgment or missed judgment. By dynamically adjusting the settlement displacement warning value, the system can more accurately reflect the actual wear state of the seal and improve the reliability of life assessment.

[0025] The correspondence can be expressed using lookup tables, interpolation functions, or empirical formulas to achieve rapid matching between static time intervals and settlement displacement warning values. This correspondence can be stored in the database of a local controller or remote monitoring platform for easy real-time retrieval and updates. Furthermore, this correspondence can be dynamically corrected based on factors such as equipment operating environment, hydraulic system pressure level, and aging characteristics of sealing materials, thereby further improving warning accuracy and adaptability.

[0026] In one specific embodiment, the static time period of the luffing cylinder 30 is T. If T is less than 24 hours, and the leakage settlement displacement of the luffing cylinder 30 is greater than n1... When S1, it is determined that the seals of the luffing cylinder 30 need to be replaced; if T is greater than 24 hours and less than 168 hours, when the leakage settlement displacement of the luffing cylinder 30 is greater than n2 At time S1, it is determined that the seals of the luffing cylinder 30 need to be replaced; if T is greater than 168 hours, when the leakage settlement displacement of the luffing cylinder 30 is greater than n3 At step S1, it is determined that the seals of the luffing cylinder 30 need to be replaced. Here, n1, n2, and n3 are coefficients, and 1 < n1 < n2 < n3. For example, n1 can be 2, n2 can be 3, and n3 can be 6. The coefficients n1, n2, and n3 can be adjusted based on actual monitoring data and the model of the luffing cylinder 30, etc.

[0027] In one specific embodiment, the static time period of the luffing cylinder 30 can be selected as 10~16 hours (corresponding to the time interval between the end of get off work on a certain day and the start of work on the next day), or 34~64 hours (corresponding to the time interval between the end of get off work on a certain day and the start of work on the third day). For monitoring the displacement change of the luffing cylinder 30 within this time period, there is no need to reserve a separate detection time. The seal condition assessment can be completed directly using the equipment's natural shutdown window, improving monitoring efficiency and reducing interference with normal operation.

[0028] In one embodiment, the first and last times of the static time period are the first moment and the second moment, respectively. Obtaining the leakage settlement displacement of the luffing cylinder 30 during the static time period includes: determining the first displacement of the luffing cylinder 30 at the first moment and the second displacement at the second moment; and obtaining the settlement displacement of the luffing cylinder 30 during the static time period based on the difference between the first displacement and the second displacement.

[0029] In one embodiment, such as Figure 2 The diagram shown illustrates an application scenario of the luffing cylinder 30 provided according to an embodiment of the present invention. The luffing cylinder 30 is applied to a luffing jib tower crane. The luffing cylinder 30 drives the jib 20 to change its luffing position. Determining the first displacement of the luffing cylinder 30 at a first moment and the second displacement at a second moment includes: obtaining the first tilt angle of the jib 20 at the first moment; obtaining the second tilt angle of the jib 20 at the second moment; determining the first displacement based on the first tilt angle; and determining the second displacement based on the second tilt angle. One end of the luffing cylinder 30 is hinged to the jib 20, and the other end is hinged to the counterweight boom 10 (or tower head). The end of the jib 20 is hinged to the tower head or another position on the jib 20. The connecting rods on the jib 20, the luffing cylinder 30, and the counterweight boom 10 (or tower head) form a triangle. The extension and retraction of the luffing cylinder 30 can change the luffing position of the jib 20. Figure 2 As shown, the luffing cylinder 30 is used to drive the boom 20 to rotate around the luffing hinge point of the boom 20. The distance between the first end of the luffing cylinder 30 and the luffing hinge point is the first spacing, and the length of the connecting rod is the second spacing. Based on the first spacing, the second spacing, and the tilt angle of the boom 20, the current length of the luffing cylinder 30 can be calculated using the law of cosines.

[0030] This invention utilizes a tilt sensor to collect real-time tilt angle data of the boom 20. By combining this tilt angle data with the first and second spacing, and using geometric calculations, the extension length of the luffing cylinder 30 at different tilt angles can be calculated. In this process, the extension length of the luffing cylinder 30 can be determined using the tilt angle data detected by the tilt sensor without adding any additional mechanical structures. Specifically, a first tilt angle is acquired when the boom crane is stopped, and a second tilt angle is acquired when the boom crane is started. Based on the first and second tilt angles, the first and second displacements of the luffing cylinder 30 can be determined, respectively. The difference between the first and second displacements is the total settlement displacement of the luffing cylinder 30 during the stationary period.

[0031] Specifically, such as Figure 2 As shown, the first spacing Second spacing The length of the luffing cylinder 30 is a fixed value. The boom 20, connecting rod, and luffing cylinder 30 form a triangle. When the tilt angle of the boom 20 is zero, the included angle between the boom 20 and the connecting rod is... When the luffing cylinder 30 drives the boom 20 to rotate θ At the angle, the angle between the boom 20 and the connecting rod is （ +θ) According to the following formula (2), the current length of the luffing cylinder 30 can be obtained. The displacement of the luffing cylinder 30 can be obtained by subtracting the length of the luffing cylinder 30 in the retracted state from the current length: (2) in, This is the first spacing. This is the second spacing. This represents the current length of the luffing cylinder 30. θ For the tilt angle of the crane, Let be the angle between the boom 20 and the connecting rod when the luffing cylinder 30 is in the retracted state. According to the above formula (2), the first displacement and the second displacement can be determined respectively. By calculating the difference between the first displacement and the second displacement, the leakage settlement displacement of the luffing cylinder 30 can be obtained. Using the above method, the leakage settlement displacement of the luffing cylinder 30 can be obtained accurately and quickly, thereby accurately predicting the life of the luffing cylinder 30.

[0032] In addition, a displacement sensor can be installed on the luffing cylinder 30. The first and second displacements of the luffing cylinder 30 can be determined based on the signals transmitted by the displacement sensor. This will make the stroke monitoring of the luffing cylinder 30 more direct and accurate.

[0033] In one embodiment, the seal life monitoring method further includes: uploading a first moment, a first tilt angle, a second moment, and a second tilt angle to a remote monitoring platform; the remote monitoring platform determines the leakage settlement displacement based on the first moment, the first tilt angle, the second moment, and the second tilt angle; and when the leakage settlement displacement exceeds a warning value, the remote monitoring platform issues a life warning signal. The remote monitoring platform can centrally manage the seal status of multiple luffing jib tower cranes, enabling unified data analysis and early warning push notifications, facilitating maintenance personnel to promptly grasp the equipment's health status and arrange maintenance plans. Life warning signals can be pushed to maintenance personnel via SMS, email, or dedicated management software, ensuring timely response to potential risks and improving the safety and efficiency of tower crane operation. The first and second moments can both be recorded using GPS time. The remote monitoring platform can be an IoT platform, a mobile platform, etc.

[0034] Furthermore, the remote monitoring platform can perform intelligent monitoring of the seals of the luffing cylinder 30 throughout its entire lifecycle. The platform can record data such as the downtime and uptime of each luffing tower crane operation, the tilt angle of the boom 20 during each downtime, and the tilt angle of the boom 20 during each uptime. Based on the downtime and uptime, the platform determines the stationary period of the luffing cylinder 30. When the stationary period exceeds a preset time period, the platform calculates and records the leakage settlement displacement of the luffing cylinder 30 within that stationary period. Theoretically, there is a positive correlation between the cumulative stroke of the luffing cylinder 30 and the leakage settlement displacement. However, the leakage settlement displacement is also related to various factors. Based on historical monitoring data, the correspondence between the leakage settlement displacement and the cumulative stroke of the luffing cylinder 30 can be determined. This correspondence allows for the optimization of the corresponding coefficient values ​​for each model of the luffing cylinder 30. For example, when the cumulative stroke of the luffing cylinder 30 has reached a preset stroke value... At that time, a corresponding coefficient value k can be determined, where k is a rational number greater than 1. Then, in the current stroke, the warning value of the settlement displacement of the variable amplitude cylinder 30 is k. ,in, This is the warning value for leakage settlement displacement of the luffing cylinder 30 when the seals are newly replaced. If the leakage settlement displacement of the luffing cylinder 30 during a certain static period exceeds the warning value corresponding to its cumulative stroke, it indicates that the seals of the luffing cylinder 30 have other manufacturing defects, or that the seals may fail prematurely during operation, requiring a thorough inspection of the seals of the luffing cylinder 30. Furthermore, in specific embodiments, if the static period is too short to be meaningful for monitoring, the aforementioned downtime, startup time, and leakage settlement displacement may not need to be uploaded to the remote monitoring platform. If the cumulative stroke of the luffing cylinder 30 reaches a preset set stroke, the remote monitoring platform can also issue a lifespan warning signal to remind the operator to replace the seals of the luffing cylinder 30 in a timely manner.

[0035] In one embodiment, the leakage settlement displacement of the luffing cylinder 30 during the next static period can be predicted based on the cumulative stroke of the luffing cylinder 30 and the leakage settlement displacement during the recent static period. For example, based on the average leakage settlement displacement of each static period in the previous month, the predicted leakage settlement displacement for the next static period can be predicted. The operator can then be prompted via the tower crane's display screen to adjust the position of the luffing tower crane before shutdown to prevent the luffing cylinder 30 from settling and causing the boom 20 to collide with buildings or other structures.

[0036] In one embodiment, the leakage settlement displacement corresponding to a static period of 1 day can be determined experimentally as S1, and the leakage settlement displacement corresponding to a static period of 2 days can be determined as (n1). S1), the leakage settlement displacement corresponding to a static period of 3 days is (n2) S1), the leakage settlement displacement corresponding to a static period of 7 days is (n3) S1), etc., where n1, n2, and n3 are all greater than 1. The values ​​can be appropriately increased based on the leakage settlement displacement determined by the experiment to obtain the above-mentioned settlement displacement warning value. In addition, the leakage settlement displacement determined by the experiment can be used to predict the leakage settlement displacement during the next shutdown process to prevent the boom 20 from colliding with obstacles due to leakage settlement of the luffing cylinder 30.

[0037] In one embodiment, the first and last times of the static time period are the first moment and the second moment, respectively. Obtaining the leakage settlement displacement of the luffing cylinder 30 during the static time period includes: obtaining the first hydraulic oil temperature and the second hydraulic oil temperature of the luffing cylinder 30 at the first moment and the second hydraulic oil temperature at the second moment; obtaining the first displacement at the first moment and the total settlement displacement of the luffing cylinder 30 at the second moment; determining the temperature displacement of the luffing cylinder 30 affected by temperature based on the first hydraulic oil temperature, the second hydraulic oil temperature, and the first displacement; and determining the leakage settlement displacement of the luffing cylinder 30 based on the difference between the total settlement displacement and the temperature displacement. In this embodiment of the invention, considering the influence of temperature changes on the total settlement displacement, the temperature displacement of the luffing cylinder 30 affected by temperature can be determined by obtaining the first hydraulic oil temperature, the second hydraulic oil temperature, and the first displacement. By calculating the difference between the total settlement displacement and the temperature displacement, the leakage settlement displacement of the luffing cylinder 30 during the static time period can be obtained.

[0038] Specifically, when the luffing cylinder 30 is extended, the weight of the boom and piston rod is borne by the hydraulic oil in the rodless chamber. Therefore, the hydraulic oil pressure in the rodless chamber is significantly higher than that in the rod chamber. When the temperature changes, the hydraulic oil pressure in the rodless chamber remains relatively stable. However, due to thermal expansion and contraction, the volume of the hydraulic oil in the rodless chamber increases or decreases, causing the luffing cylinder 30 to extend or retract, resulting in the aforementioned temperature displacement. In contrast, the hydraulic oil pressure in the rod chamber is lower, resulting in a smaller temperature-dependent change in its volume. In actual calculations, the displacement change caused by thermal expansion and contraction of the hydraulic oil in the rodless chamber is negligible.

[0039] Furthermore, when the hydraulic oil temperature difference between the first and second moments is small, the effect of temperature on the volume of hydraulic oil in the rodless chamber can be ignored, and the total settlement amount mentioned above can be determined as the leakage settlement displacement of the luffing cylinder 30. In embodiments that consider the effect of temperature, the first and second hydraulic oil temperatures can also be uploaded to a remote monitoring platform so that the remote monitoring platform can calculate the leakage settlement displacement more accurately.

[0040] In one embodiment, the static time interval is positively correlated with the settlement displacement warning value. For example, when the static time interval is short, the system sets a lower settlement displacement warning value to improve sensitivity; while when the static time interval is long, a relatively large settlement is allowed, thus balancing detection accuracy with the rationality of actual working conditions.

[0041] In one embodiment, the temperature displacement is determined according to the following formula (1): (1) in, This is the temperature displacement. The coefficient of thermal expansion of hydraulic oil. This is the difference between the temperature of the first hydraulic oil and the temperature of the second hydraulic oil. The first displacement is the displacement of the luffing cylinder 30. The extension displacement of the luffing cylinder 30 corresponds to the length of the rodless chamber of the luffing cylinder 30. The longer the rodless chamber, the higher the temperature displacement of the luffing cylinder 30 tends to be, because the hydraulic oil pressure in the rodless chamber is greater and more significantly affected by temperature changes. Therefore, by incorporating the first displacement into the calculation of the temperature displacement, non-leakage settlement caused by thermal expansion and contraction can be compensated more accurately, thereby improving the accuracy of identifying leakage settlement displacement. Furthermore, the temperature displacement also considers the difference between the first and second hydraulic oil temperatures, making the temperature compensation model closer to actual working conditions and effectively eliminating the interference of hydraulic oil temperature fluctuations on the judgment of leakage settlement displacement. The thermal expansion coefficient of the hydraulic oil is related to the type and temperature range of the hydraulic oil, and the specific value of the hydraulic oil thermal expansion coefficient can be determined according to the type and temperature range of the hydraulic oil. In a specific embodiment, the hydraulic oil thermal expansion coefficient is taken as (8.7 × 10⁻⁶). -4 / ℃).

[0042] In one embodiment, such as Figure 2 As shown, the method for monitoring the life of the seals also includes: recording the extension and retraction stroke of the luffing cylinder 30 in real time during luffing operation; and determining that the seals of the luffing cylinder 30 need to be replaced if the cumulative stroke of the luffing cylinder 30 is greater than the set stroke. The extension and retraction stroke is the relative displacement of the seals of the luffing cylinder 30 relative to the cylinder body during a single extension and retraction movement, and the cumulative stroke is the cumulative relative displacement of the piston relative to the cylinder body during the entire life cycle of the luffing cylinder 30. The extension and retraction stroke of the luffing cylinder 30 can be determined according to the following formula (3): (3) in, This refers to the extension and retraction stroke of the luffing cylinder 30. The first spacing is defined as the distance between the first end of the luffing cylinder 30 and the luffing hinge point. The second spacing is defined as the distance between the second end of the luffing cylinder 30 and the luffing hinge point. The angle between the boom 20 and the connecting rod when the tilt angle of the luffing cylinder 30 is zero. This refers to the tilt angle of the boom 20 after a single luffing maneuver. This is the tilt angle of the boom 20 at the start of a single luffing motion.

[0043] The cumulative stroke of the variable amplitude cylinder 30 can be determined according to the following formula (4): (4) in, To accumulate trips, This is the cumulative travel distance since the last amplitude change. This refers to the extension / retraction stroke of this amplitude change action.

[0044] During the extension and retraction of the luffing cylinder 30, the seals of the dynamic seal gradually wear due to friction and pressure cycles. Accumulated stroke is a crucial indicator of its mechanical fatigue. By integrating a stroke sensor into the system or calculating the number and amplitude of extensions and retractions based on tilt angle data, the effective stroke of the luffing cylinder 30 can be accumulated in real time. When this accumulated value exceeds a preset lifespan threshold, even if the leakage settlement displacement is within limits, the seal should be replaced to achieve multi-dimensional lifespan assessment. This prevents sudden seal failure due to prolonged use. The lifespan threshold can be determined based on industry standards, product materials, or manufacturer requirements.

[0045] In one embodiment, the seal life monitoring method further includes: when it is determined that the seal of the luffing cylinder 30 needs to be replaced, controlling the alarm unit to issue an alarm prompt; and inspecting the luffing cylinder 30 according to the alarm prompt to determine the seal that needs to be replaced. There are multiple seals that affect the sealing performance of the luffing cylinder 30, such as the sealing ring between the piston and the inner peripheral wall of the cylinder, the sealing ring between the piston rod and the cylinder, and the seal at the balance valve. After receiving the alarm prompt, the operator can specifically inspect the relevant sealing parts, determine the specific failure location, and replace the seal accordingly.

[0046] In one embodiment, a sealing life monitoring system for a luffing cylinder 30 is provided. The sealing life monitoring system includes: a displacement monitoring unit for acquiring the leakage settlement displacement of the luffing cylinder 30 during a static period; a life determination unit for determining a settlement displacement warning value corresponding to the static period, and determining that the sealing of the luffing cylinder 30 needs to be replaced if the leakage settlement displacement exceeds the settlement displacement warning value; and an alarm unit for issuing an alarm prompt when it is determined that the sealing needs to be replaced.

[0047] In one embodiment, a luffing tower crane is provided, including the above-described sealing life monitoring system for the luffing cylinder 30 and the luffing cylinder 30.

[0048] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for monitoring the lifespan of seals in a variable amplitude hydraulic cylinder, characterized in that, The method for monitoring the lifespan of the seal includes: When the luffing cylinder (30) is stationary in the detection posture, the leakage settlement displacement of the luffing cylinder (30) during the stationary period is obtained; Determine the early warning value of settlement displacement corresponding to the static time period; If the leakage settlement displacement is greater than the settlement displacement warning value, it is determined that the seal of the variable amplitude cylinder (30) needs to be replaced.

2. The method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder according to claim 1, characterized in that, The determination of the settlement displacement warning value corresponding to the static time period includes: Construct the correspondence between the static time interval of the variable amplitude cylinder (30) and the early warning value of the settlement displacement; Determine the static time interval corresponding to the static time period; Based on the correspondence, the early warning value of the settlement displacement corresponding to the static time period is determined.

3. The method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder according to claim 1, characterized in that, The first and last times of the static time period are the first moment and the second moment, respectively. The acquisition of the leakage settlement displacement of the variable amplitude cylinder (30) during the static time period includes: Determine the first displacement of the variable amplitude cylinder (30) at the first moment and the second displacement at the second moment; The settlement displacement of the variable amplitude cylinder (30) during the static time period is obtained based on the difference between the first displacement and the second displacement.

4. The method for monitoring the lifespan of the seals of the variable amplitude cylinder according to claim 3, characterized in that, The luffing cylinder (30) is used in a luffing tower crane, and the luffing cylinder (30) is used to drive the boom (20) to luff. Determining the first displacement of the luffing cylinder (30) at the first moment and the second displacement at the second moment includes: Obtain the first tilt angle of the lifting boom (20) at the first moment; Obtain the second tilt angle of the lifting boom (20) at the second moment; The first displacement is determined based on the first tilt angle, and the second displacement is determined based on the second tilt angle; Alternatively, the first displacement and the second displacement can be determined based on the signal transmitted by the displacement sensor on the variable amplitude cylinder (30).

5. The method for monitoring the lifespan of the seals of a variable-amplitude cylinder according to claim 4, characterized in that, The method for monitoring the lifespan of the seal also includes: Upload the first moment, the first tilt angle, the second moment, and the second tilt angle to the remote monitoring platform; The remote monitoring platform determines the leakage settlement displacement based on the first time, the first inclination angle, the second time, and the second inclination angle; If the leakage settlement displacement exceeds the warning value for settlement displacement, the remote monitoring platform issues a lifespan warning signal.

6. The method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder according to claim 1, characterized in that, The first and last times of the static time period are the first moment and the second moment, respectively. The acquisition of the leakage settlement displacement of the variable amplitude cylinder (30) during the static time period includes: The first hydraulic oil temperature of the variable amplitude cylinder (30) at the first moment and the second hydraulic oil temperature at the second moment are obtained; Obtain the first displacement at the first moment and the total settlement displacement of the variable amplitude cylinder (30) during the static time period; Based on the first hydraulic oil temperature, the second hydraulic oil temperature, and the first displacement, determine the temperature displacement of the variable amplitude cylinder (30) affected by temperature. The leakage settlement displacement of the variable amplitude cylinder (30) is determined based on the difference between the total settlement displacement and the temperature displacement.

7. The method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder according to claim 6, characterized in that, The temperature displacement is determined according to the following formula (1): （1） in, The temperature displacement is... The coefficient of thermal expansion of hydraulic oil. The difference between the temperature of the first hydraulic oil and the temperature of the second hydraulic oil. This is the first displacement.

8. The method for monitoring the lifespan of seals in a variable-amplitude hydraulic cylinder according to claim 1, characterized in that, The method for monitoring the lifespan of the seal also includes: When the luffing cylinder (30) is working, the extension and retraction stroke of the luffing cylinder (30) is recorded in real time; If the cumulative stroke of the luffing cylinder (30) is greater than the set stroke, it is determined that the seal of the luffing cylinder (30) needs to be replaced.

9. The method for monitoring the lifespan of the seals of a variable-amplitude cylinder according to any one of claims 1 to 8, characterized in that, The method for monitoring the lifespan of the seal also includes: If it is determined that the seals of the variable amplitude cylinder (30) need to be replaced, a warning message shall be issued; The variable amplitude cylinder (30) is inspected according to the warning prompt to determine the seals that need to be replaced.

10. A sealing component life monitoring system for a variable amplitude hydraulic cylinder, characterized in that, The seal life monitoring system includes: The displacement monitoring unit is used to obtain the leakage settlement displacement of the variable amplitude cylinder (30) during the static period; The lifespan determination unit is used to determine the settlement displacement warning value corresponding to the static time period. If the leakage settlement displacement is greater than the settlement displacement warning value, it is determined that the seal of the variable amplitude cylinder (30) needs to be replaced. The warning unit is used to issue a warning when it is determined that the seal needs to be replaced.

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