Electro-hydraulic cylinder and related methods

Abstract

The application is suitable for the technical field of hydraulic cylinders, and particularly relates to an electric hydraulic cylinder and a related method. The electric hydraulic cylinder comprises a direct current motor, a hydraulic oil pump, a hydraulic oil cylinder, a front end ear ring, a rear end ear ring and an end face limit deviation checking element. The direct current motor comprises a power output part, the hydraulic oil pump has a power input part and is arranged on the power output side of the direct current motor. The hydraulic oil cylinder is arranged along the extension and retraction direction of the electric hydraulic cylinder. The front end ear ring is located on the side away from the direct current motor and the hydraulic oil pump. The rear end ear ring is oppositely arranged with the front end ear ring along the extension and retraction direction of the electric hydraulic cylinder, and is located on the end close to the direct current motor and the hydraulic oil pump. The end face limit deviation checking element comprises a positioning part for positioning cooperation with the front end ear ring and an end face distance measuring area oppositely arranged along the radial direction of the front end ear ring. The problem that the abnormal pressure maintenance is misjudged and the troubleshooting direction is deviated due to the difficulty in identifying the load deviation based on the gap change between the two sides before the pressure maintenance test can be solved.

Description

Technical Field

[0001] This application belongs to the field of hydraulic cylinder technology, and particularly relates to electric hydraulic cylinders and related methods. Background Technology

[0002] An electric hydraulic cylinder typically integrates a DC motor, a hydraulic pump, and a hydraulic cylinder into a single actuator. The motor drives the hydraulic pump to supply oil to the hydraulic cylinder, thereby enabling actions such as extending, retracting, lifting, or tilting.

[0003] In vehicle tilting mechanisms, lifting mechanisms, and other equipment requiring compact hydraulic actuators, electro-hydraulic cylinders are typically connected to external mounting structures via front and rear lugs. To verify the operational status of components such as the hydraulic cylinder, pressure holding valve, and sealing pairs, electro-hydraulic cylinders usually undergo operational testing, low-load testing, or pre-pressure holding testing checks after assembly or before leaving the factory. During testing, the assembly condition at the front lug affects the stress state of the electro-hydraulic cylinder. If the gaps on both sides of the end face of the front lug are uneven, the external mounting reference is misaligned, or the mounting end has already formed a localized load before entering the pressure holding test, the output rod, guide structure, or sealing pair of the electro-hydraulic cylinder may be subjected to additional lateral forces. These additional forces do not necessarily originate from the hydraulic circuit, pressure holding valve, or the internal sealing structure of the hydraulic cylinder itself, and may manifest as abnormal pressure holding, sluggish operation, or fluctuations in test data during subsequent pressure holding tests.

[0004] Current pre-pressure holding test inspection methods typically focus on routine checks of hydraulic circuits, pressure holding valves, sealing pairs, or external connectors, or rely on manual experience to observe whether the installation is aligned. While these methods can detect obvious assembly defects or internal leakage risks, they lack the local structural foundation for establishing stable clearance data on both sides of the front lug end face. This makes it difficult to convert the off-center load trend at the installation end into readable, comparable, and verifiable data before the pressure holding test. Therefore, when abnormal phenomena occur during the pressure holding test, existing methods easily misinterpret external interference caused by off-center load at the front lug installation end as an abnormality in the cylinder body, pressure holding valve, or hydraulic circuit, leading to an extended troubleshooting path or a deviation in the correction direction. Summary of the Invention

[0005] This application provides an electric hydraulic cylinder and related methods, which can solve the problem that the gap changes on both sides of the front ear ring end face are difficult to form a comparable basis for identifying off-center load before the pressure holding test, which leads to the abnormal appearance of the pressure holding test being easily misjudged as abnormality of the hydraulic cylinder, pressure holding valve or hydraulic circuit, thus causing the troubleshooting path to be extended or the correction direction to deviate.

[0006] In a first aspect, embodiments of this application provide an electric hydraulic cylinder, comprising: DC motor, including power output unit; The hydraulic oil pump has a power input unit that is drively connected to the power output unit, and the hydraulic oil pump is disposed on the power output side of the DC motor; A hydraulic cylinder is arranged along the extension and retraction direction of the electric hydraulic cylinder; the working chamber of the hydraulic cylinder is connected to the oil outlet of the hydraulic pump through a hydraulic oil circuit. The front earring is located on the side away from the DC motor and the hydraulic pump; A rear end ring, wherein the rear end ring and the front end ring are positioned opposite each other along the extension / retraction direction of the electric hydraulic cylinder, and the rear end ring is located at the end closest to the DC motor and the hydraulic pump; the DC motor and the hydraulic pump are located on one side of the hydraulic cylinder and close to the rear end ring, and the hydraulic pump is located between the oil circuit connection area of ​​the DC motor and the hydraulic cylinder; and An end face deviation limiting calibration component is disposed on the end face side of the front earring. The end face deviation limiting calibration component includes a positioning part that cooperates with the positioning of the front earring and an end face ranging area arranged radially opposite to the front earring.

[0007] The technical solutions described in this application embodiment have at least the following technical effects: The electric hydraulic cylinder provided in this application can achieve a positioning fit between the calibration component and the front earring by setting an end face deviation limit calibration component on the end face side of the front earring. This avoids radial offset interference with measurement accuracy. Furthermore, by using two radially opposite end face distance measuring areas, it is possible to directly obtain the gap data on both sides of the front earring end face relative to the external mounting reference before assembly or pressure holding test. This allows the off-center load state to be directly converted into a quantifiable and comparable gap parameter, providing a stable structural basis for off-center load identification before pressure holding test. This facilitates technicians to identify off-center load trends and determine off-center load direction in advance. It can directly obtain the gap data on both sides of the front earring end face relative to the external mounting reference before assembly or pressure holding test, providing a quantifiable and comparable structural basis for off-center load identification before pressure holding test, shortening the anomaly troubleshooting path, correcting the troubleshooting direction, and improving the efficiency and accuracy of test troubleshooting.

[0008] Secondly, embodiments of this application provide a method for identifying off-center load before pressure holding in an electric hydraulic cylinder, applied to the electric hydraulic cylinder described in the first aspect above, the method comprising: Determine the initial end face gap data formed between the two end face ranging regions and the external mounting reference in the initial state; wherein, the initial end face gap data is used to indicate the reference gap between each of the two end face ranging regions and the external mounting reference when the electric hydraulic cylinder has not entered the pressure holding test state; When the electric hydraulic cylinder is in the pre-pressure holding test state, determine the two-sided state end face gap data formed between the two end face distance measurement areas and the external mounting reference; wherein, the two-sided state end face gap data is used to indicate the pre-pressure holding test gap of each of the two end face distance measurement areas relative to the external mounting reference when the electric hydraulic cylinder is in the pre-pressure holding test state. Based on the correspondence between the two end face ranging areas, the end face gap change data is determined according to the initial end face gap data on both sides and the state end face gap data on both sides; wherein, the end face gap change data is used to indicate the difference between the state end face gap before pressure holding and the initial end face gap; Based on the difference between the changes in the gap between the two end faces in the end face gap change data, off-center load characterization data is determined to characterize the degree of unevenness in the change of the gap between the two end faces. The off-center load characterization data is analyzed, and combined with the trend of the gap change on both sides indicated in the end face gap change data, off-center load identification data before pressure holding test is obtained; wherein, the off-center load identification data includes off-center load direction data determined based on the magnitude relationship of the gap change on both sides and off-center load degree data determined based on the difference in the gap change on both sides.

[0009] The technical solutions described in this application embodiment have at least the following technical effects: This application provides a method for identifying off-center load before pressure holding in an electric hydraulic cylinder. By comparing the gap changes on both ends of the cylinder in the initial state and the test state before pressure holding, the method quantifies the degree of unevenness in the gap changes on both sides, directly obtaining the clear direction and degree of off-center load. This transforms the off-center load trend, which originally relied on manual experience for judgment, into readable, comparable, and verifiable quantitative data. This allows technicians to identify off-center load problems at the front end of the lug mounting before the pressure holding test, adjust the assembly state in advance, and avoid misjudging abnormal phenomena caused by off-center load as cylinder body or hydraulic system failures during the pressure holding test. This effectively shortens the path of anomaly troubleshooting and improves the efficiency and accuracy of testing and troubleshooting. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the structure of an electric hydraulic cylinder provided in one embodiment of this application; Figure 2This is a two-dimensional structural schematic diagram of an electric hydraulic cylinder provided in an embodiment of this application; Figure 3 This is a schematic diagram illustrating the implementation process of the electro-hydraulic cylinder pressure-holding pre-offset load identification method provided in an embodiment of this application; Figure 4 This is a schematic diagram of a scenario provided by an embodiment of the present application for determining the gap data between the two end face states formed between the two end face ranging areas and the external mounting reference; Figure 5 This is a schematic diagram of a scenario for determining end face gap change data provided in an embodiment of this application; Figure 6 This is a schematic diagram of a scenario for determining off-center load characterization data provided in an embodiment of this application; Figure 7 This is a schematic diagram of a scenario for determining off-center load identification data before a pressure holding test, provided in an embodiment of this application. Figure 8 This is a schematic diagram of the controller provided in the embodiments of this application.

[0012] The following are the labeling elements in the figure: 100. Electric hydraulic cylinder; 10. DC motor; 20. Hydraulic oil pump; 30. Hydraulic oil cylinder; 40. Front end ear; 50. Rear end ear; 60. End face deviation check component; 61. Positioning part; 62. End face distance measuring area. Detailed Implementation

[0013] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0014] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0015] Existing electro-hydraulic cylinders typically integrate a DC motor, hydraulic pump, and hydraulic cylinder into a single actuator. The motor drives the hydraulic pump to supply oil to the hydraulic cylinder, achieving actions such as extension, retraction, lifting, or tilting. In equipment requiring compact hydraulic actuators, such as vehicle tilting mechanisms and lifting mechanisms, the electro-hydraulic cylinder connects to the external mounting structure via front and rear lugs. After assembly or before leaving the factory, to verify the working status of components such as the hydraulic cylinder, pressure holding valve, and sealing pairs, pre-inspections such as motion tests, low-load tests, or pressure holding tests are usually performed.

[0016] However, during testing, the assembly state of the front end ear directly affects the stress state of the electric hydraulic cylinder. The inventors of this application have discovered that if the gap between the two sides of the end face of the front end ear is uneven, the external mounting reference is misaligned, or the mounting end has already formed a localized off-center load before entering the pressure holding test, the output rod, guide structure, or sealing pair of the electric hydraulic cylinder will be subjected to additional lateral forces. These additional lateral forces do not originate from the hydraulic circuit, pressure holding valve, or the internal sealing structure of the hydraulic cylinder itself, but may manifest as abnormal pressure holding, sluggish action, or fluctuations in test data during subsequent pressure holding tests. Existing troubleshooting methods focus on routine inspections of the hydraulic circuit, pressure holding valve, sealing pair, or external connectors, or rely on manual experience to observe whether the installation is aligned. While these methods can identify obvious assembly defects or internal leakage risks, they lack the structural basis for in-situ detection of the gap between the two sides of the end face of the front end ear and thus for identifying the off-center load. Therefore, it is difficult to convert the off-center load trend at the mounting end into readable, comparable, and verifiable data before the pressure holding test. Therefore, when abnormal phenomena occur during the pressure holding test, the external interference caused by the off-center load at the front end of the earpiece is easily misjudged as an abnormality in the cylinder body, pressure holding valve, or hydraulic circuit, leading to an extended troubleshooting path and a deviation in the correction direction.

[0017] To address the aforementioned problems, this application provides an electric hydraulic cylinder and related methods.

[0018] Please refer to the following: Figure 1 and Figure 2 This application provides an electric hydraulic cylinder 100, including a DC motor 10, a hydraulic oil pump 20, a hydraulic cylinder 30, a front end lug 40, a rear end lug 50, and an end face deviation limiting and checking component 60, wherein: The DC motor 10 includes a power output section. The hydraulic oil pump 20 has a power input section that is drively connected to the power output section, and the hydraulic oil pump 20 is located on the power output side of the DC motor 10.

[0019] The hydraulic cylinder 30 is arranged along the extension and retraction direction of the electric hydraulic cylinder 100; the working chamber of the hydraulic cylinder 30 is connected to the oil outlet of the hydraulic pump 20 through a hydraulic oil circuit. The front lug 40 is located on the side away from the DC motor 10 and the hydraulic pump 20.

[0020] The rear end ear 50 and the front end ear 40 are arranged opposite each other along the extension and retraction direction of the electric hydraulic cylinder 100, and the rear end ear 50 is located at the end close to the DC motor 10 and the hydraulic oil pump 20; the DC motor 10 and the hydraulic oil pump 20 are arranged on one side of the hydraulic cylinder 30 and close to the rear end ear 50, and the hydraulic oil pump 20 is located between the oil circuit connection area of ​​the DC motor 10 and the hydraulic cylinder 30.

[0021] The end face deviation calibration component 60 is disposed on the end face side of the front earring 40. The end face deviation calibration component 60 includes a positioning part 61 that is positioned and cooperates with the front earring 40, and an end face ranging area 62 that is arranged radially opposite to the front earring 40.

[0022] It can be understood that the electric hydraulic cylinder 100 is an integrated actuator that uses a DC motor 10 as a power source, converts mechanical energy into hydraulic energy through a hydraulic pump 20, and then outputs linear extension and retraction motion through a hydraulic cylinder 30. Specifically, the DC motor 10 converts electrical energy into rotational mechanical energy, serving as the power input of the entire hydraulic system; the hydraulic pump 20 converts the rotational motion output by the DC motor 10 into the directional flow and pressure output of hydraulic oil, serving as the pressure source of the hydraulic circuit; and the hydraulic cylinder 30 converts the pressure energy of the hydraulic oil into the linear extension and retraction displacement of the piston rod, serving as the action output of the entire electric hydraulic cylinder 100. The front lug 40 is used to hinge the front end of the electro-hydraulic cylinder 100 to the external driven component and bear the push and pull loads during operation. The rear lug 50 is used to connect the rear end of the electro-hydraulic cylinder 100 to the external fixed base to provide an installation reference and reaction force support; The positioning part is a mating structure that forms a radial positioning fit with the outer cylindrical surface or end face edge of the front end ear 40. It is used to radially position the end face deviation calibration member 60 relative to the front end ear 40 through the radial fit with the outer cylindrical surface of the front end ear 40. The positioning part can be a boss structure that forms a radial positioning fit with the outer cylindrical surface of the front end ear 40. The end face ranging area 62 consists of two measuring reference surfaces arranged radially opposite to each other on the end face deviation calibration member 60 along the front end ear 40. The end face ranging area 62 is used to directly obtain the gap between the corresponding end face ranging area on each radial side and the external mounting reference. In the case of contact gap measurement, the end face ranging area 62 consists of two flat measuring reference surfaces to cooperate with feeler gauges or dial indicators for contact gap measurement. In the case of non-contact gap measurement, the measuring reference surfaces of the end face ranging area 62 are measuring reference surfaces for mounting measuring components, such as laser displacement sensors, to achieve non-contact measurement.

[0023] Specifically, during operation, the DC motor 10 receives external control signals or power supply, and its power output section outputs rotational torque. This rotational torque is transmitted to the power input section of the hydraulic oil pump 20 through a transmission connection, driving the gear pair or plunger pair inside the hydraulic oil pump 20 to draw hydraulic oil from the oil tank or low-pressure chamber, pressurize it, and then discharge it from the oil outlet. The pressurized hydraulic oil is transported along the hydraulic oil circuit to the working chamber of the hydraulic cylinder 30, pushing the piston inside the hydraulic cylinder 30 to move in the extension and retraction direction, thereby driving the external component connected to the front end ear 40 to complete the extension and retraction action. Before entering the pressure holding test state, technicians can use the two radially opposite end face measuring areas 62 on the end face limit calibration component 60 to measure and record the gap values ​​of both sides of the end face of the front end ear 40 relative to the external mounting reference, and conduct a specific comparative analysis of the gap data on both sides to determine whether there is an off-center load trend and the direction of the off-center load.

[0024] As can be seen from the above, the electric hydraulic cylinder 100 provided in this application can achieve the positioning and cooperation between the calibration component and the mounting hole by setting an end face deviation calibration component 60 on the end face side of the front end ear 40 and using the positioning part 61 to avoid radial deviation interfering with the measurement accuracy. Furthermore, by using two end face distance measuring areas 62 arranged radially opposite to each other, the clearance data of the two sides of the end face of the front end ear 40 relative to the external mounting reference can be obtained directly before assembly or pressure holding test. This allows the off-center load state to be directly converted into a quantifiable and comparable clearance parameter, providing a stable structural basis for off-center load identification before pressure holding test. This facilitates technicians to identify the off-center load trend and determine the off-center load direction in advance, avoiding misjudging the pressure holding abnormality caused by off-center load as a fault of the hydraulic cylinder 30 or the hydraulic circuit itself, shortening the abnormality troubleshooting path, correcting the troubleshooting direction, and improving the efficiency and accuracy of testing and troubleshooting.

[0025] Alternatively, the measurement reference surface can be a laser displacement sensor, an eddy current displacement sensor, or a capacitive gap sensor to achieve non-contact measurement.

[0026] In some embodiments, please refer to the following: Figure 1 and Figure 2 The positioning part 61 abuts against the hole wall or the edge of the hole of the front earring 40 to limit the radial displacement of the end face deviation checker 60 relative to the front earring 40.

[0027] It can be understood that the mating object of the positioning part 61 is the hole wall (i.e., the inner cylindrical surface of the mounting hole) or the edge of the hole opening (i.e., the outer edge of the end face of the mounting hole) of the front ear 40. When the positioning part 61 is against the hole wall, a clearance fit or transition fit is formed between the outer cylindrical surface of the positioning part 61 and the inner cylindrical surface of the mounting hole, and the radial degree of freedom is constrained by the surface contact. When the positioning part 61 is against the edge of the hole opening, the positioning part 61 is engaged with the edge of the hole opening by an annular groove, a stepped surface or an elastic claw, and stable positioning is achieved by dual constraints of axial compression and radial limiting.

[0028] For example, when assembling the positioning part 61, if the positioning part 61 is implemented as a cylindrical boss that matches the inner diameter of the front earring 40, the boss can be pushed axially into the mounting hole until the end face of the boss or the positioning step abuts against the end face of the mounting hole. At this time, the outer cylindrical surface of the boss and the hole wall form a surface contact for radial positioning. If the positioning part 61 is implemented as an elastic buckle, the buckle can be aligned with the edge of the hole and pressed with force, so that the elastic arm of the buckle contracts radially and then passes through the hole and springs back open on the inner side of the hole wall, and is engaged on the inner side of the edge of the hole, thereby achieving dual axial and radial positioning.

[0029] With this configuration, the positioning part 61 abuts against the hole wall or the edge of the hole of the front ear 40, and the mounting hole itself can be used as the positioning reference to eliminate the installation gap and radial degree of freedom of the end face limit calibration part 60. This ensures that the relative position relationship of the end face measuring area 62 remains consistent during multiple disassembly and assembly and use, thereby making the repeatability and comparability of the gap data on both sides of the end face more consistent and avoiding the misjudgment of the off-center load direction caused by the measurement deviation introduced by the radial offset of the calibration part.

[0030] Optionally, in some embodiments, please also refer to Figure 1 and Figure 2 The radially opposite end face ranging area 62 is symmetrically arranged with respect to the central axis of the front earring 40.

[0031] It can be understood that radially opposite arrangement means that the two end-face ranging areas 62 are located at opposite ends of the radial direction of the front earring 40, that is, one end-face ranging area 62 is located on the first radial side of the mounting hole, and the other end-face ranging area 62 is located on the second radial side in the opposite direction of the diameter from the first side. Symmetrical arrangement relative to the central axis of the front earring 40 means that the line connecting the geometric centers or effective measurement points of the two end-face ranging areas 62 passes through the central axis of the mounting hole, and the distances to the central axis are equal. Symmetrical arrangement enables the two end-face ranging areas 62 to have the same geometric sensitivity to the off-center tilt of the end face of the front earring 40, that is, when the mounting end face undergoes the same off-center tilt, the gap changes of the two ranging areas are theoretically equal in magnitude and opposite in sign, that is, the gap on one side decreases and the gap on the other side increases.

[0032] For example, when manufacturing the end face deviation limiting calibration part 60, two end face measuring areas 62 are machined at two positions symmetrical to the center of the positioning part 61 on the calibration part body, so that the normal direction of the measuring surface of the two end face measuring areas 62 is parallel to the axial direction of the front end ear 40, and the radial distance from the installation position of the two measuring surfaces to the center of the positioning part 61 is equal. During measurement, the gap values ​​between the two end face measuring areas 62 and the external mounting reference are read respectively. If the electric hydraulic cylinder 100 is well installed and there is no off-center load, the gap values ​​on both sides should be approximately equal or the difference should be within the preset tolerance range; if there is off-center load, the gap values ​​on both sides will show an asymmetrical change with one side decreasing and the other side increasing.

[0033] This configuration, by symmetrically arranging the end face ranging area 62 relative to the central axis of the front end ear ring 40, enables the symmetrical and consistent response of the gap measurement on both sides to the off-center tilt, eliminating the difference in measurement sensitivity caused by the asymmetrical arrangement of the ranging area.

[0034] Optionally, in some embodiments, please also refer to Figure 1 and Figure 2 A pressure holding valve is provided inside the hydraulic cylinder 30. The pressure holding valve is located at the connection between the working chamber of the hydraulic cylinder 30 and the hydraulic oil circuit, and the opening direction of the pressure holding valve is from the hydraulic oil circuit to the working chamber.

[0035] It can be understood that a pressure-holding valve is a hydraulic one-way control valve used to maintain a preset pressure level within the working chamber of a hydraulic cylinder 30. The connection port refers to the oil passage opening on the cylinder body of the hydraulic cylinder 30 that connects the hydraulic oil circuit to the internal working chamber of the cylinder body. The fact that the pressure-holding valve is located at this connection port indicates that its inlet is connected to the hydraulic oil circuit and its outlet is connected to the working chamber, making the pressure-holding valve the only controlled channel for hydraulic oil to enter the working chamber. The opening direction is from the hydraulic oil circuit to the working chamber. This means that under normal operating conditions, when the oil pressure on the hydraulic oil circuit side is greater than the pressure on the working chamber side plus the opening pressure of the pressure-holding valve itself (i.e., the valve core spring preload or pilot pressure setting), the pressure-holding valve core overcomes the spring force or pilot pressure and opens, allowing hydraulic oil to flow from the hydraulic oil circuit into the working chamber through the pressure-holding valve. Conversely, when the pressure on the hydraulic oil circuit side decreases or is eliminated, the pressure-holding valve core closes under the action of the spring force or the working chamber pressure, preventing hydraulic oil in the working chamber from flowing back into the hydraulic oil circuit, thus locking the pressure in the working chamber and achieving the pressure-holding function. The pressure-holding valve can be a spring-return check valve, a hydraulically controlled check valve, or a pilot-operated check valve.

[0036] For example, a spring-reset check valve is used. One end of the valve core is subjected to the force of a spring, and the other end is subjected to the pressure of the hydraulic circuit side. After the hydraulic pump 20 starts and pressurizes, when the pressure on the hydraulic circuit side rises to exceed the sum of the spring preload and the back pressure of the working chamber, the valve core is pushed open and hydraulic oil enters the working chamber. After the hydraulic pump 20 stops or is unloaded, the pressure on the hydraulic circuit side drops, and the valve core closes quickly under the combined action of the spring force and the high-pressure oil in the working chamber, locking the high-pressure oil in the working chamber and maintaining the working pressure of the hydraulic cylinder 30.

[0037] This configuration, by placing the pressure-holding valve directly at the connection point between the working chamber and the hydraulic circuit, shortens the ineffective cavity volume between the pressure-holding valve and the working chamber, reduces the pressure attenuation caused by the compressibility of the oil in the cavity and the expansion of the pipeline, and improves the pressure holding accuracy and response speed. Furthermore, by limiting the opening direction of the pressure-holding valve to be from the hydraulic circuit to the working chamber, it can automatically block the return oil passage after the hydraulic pump 20 stops supplying oil, prevent the backflow of pressurized oil in the working chamber, and ensure that the hydraulic cylinder 30 can still maintain output force after power failure or pump stoppage, thus meeting the functional requirements of safety protection or load holding.

[0038] Optionally, in some embodiments, please also refer to Figure 1 and Figure 2 The pressure holding valve maintains a pressure greater than the sum of the preset pressure holding test pressure and the preset safety margin in the direction opposite to the opening direction.

[0039] It can be understood that the holding pressure of a pressure-holding valve in the direction away from opening refers to the maximum reverse pressure resistance of the valve in the closed state, preventing high-pressure oil in the working chamber from leaking from the outlet to the inlet. The preset pressure-holding test pressure refers to the target test pressure value applied to the working chamber by the hydraulic system when testing the pressure-holding performance of the electric hydraulic cylinder 100. The preset safety margin refers to a safety allowance added to the test pressure to ensure that the pressure-holding valve will not open abnormally or leak internally due to slight overpressure or pressure fluctuations during the test. It is typically taken as 10% to 25% of the preset pressure-holding test pressure or an absolute pressure value determined based on test data and engineering experience.

[0040] For example, if the preset pressure holding test pressure of the electric hydraulic cylinder 100 is 20 MPa, and the preset safety margin is 15% of the test pressure, i.e., 3 MPa, then the holding pressure of the pressure holding valve in the direction away from the opening direction should be greater than 23 MPa. In actual selection or design of the pressure holding valve, this holding pressure requirement can be met by selecting a valve core and valve seat pair with greater spring stiffness, smaller valve seat sealing area, or higher sealing material hardness.

[0041] This configuration, by constraining the holding pressure of the pressure-holding valve in the direction away from opening to be greater than the sum of the preset pressure-holding test pressure and the preset safety margin, ensures that the pressure-holding valve remains reliably closed and sealed throughout the entire pressure-holding test. It prevents minor internal leakage due to fluctuations in test pressure or approaching the valve's own holding pressure limit. This ensures that any pressure drop detected during the pressure-holding test is caused by leakage from the hydraulic cylinder 30 body, hydraulic circuit seals, or external connections, rather than insufficient sealing capacity of the pressure-holding valve itself. This effectively isolates the interference of the pressure-holding valve's own performance on the pressure-holding test results, enabling accurate determination of whether the leakage is caused by the cylinder body due to the off-center load or a defect in the hydraulic system components during subsequent off-center load identification and troubleshooting, thus improving the accuracy of fault location.

[0042] Furthermore, this application provides a method for identifying off-center load before pressure holding in an electric hydraulic cylinder. This method can quantify the degree of unevenness in the gap changes on both sides by comparing the gap changes on both sides between the initial state and the test state before pressure holding. This directly yields a clear direction and degree of off-center load, transforming the off-center load trend that originally relied on manual experience into readable, comparable, and verifiable quantitative data. This allows technicians to identify off-center load problems at the front end of the earpiece installation before the pressure holding test, adjust the assembly state in advance, and avoid misjudging abnormal phenomena caused by off-center load as cylinder body or hydraulic system failures during the pressure holding test. This effectively shortens the path of anomaly troubleshooting and improves the efficiency and accuracy of testing and troubleshooting.

[0043] The method for identifying off-center load before pressure holding of an electric hydraulic cylinder provided in this application embodiment can be applied to a controller. In this case, the controller is the executing entity of the method for identifying off-center load before pressure holding of an electric hydraulic cylinder provided in this application embodiment. This application embodiment does not impose any restrictions on the specific type of controller.

[0044] The controller can be an embedded control unit integrated inside the electro-hydraulic cylinder, or it can be an external computing device that is set up independently of the electro-hydraulic cylinder and interacts with the electro-hydraulic cylinder through wired or wireless communication links.

[0045] To better understand the method for identifying off-center load before pressure holding of an electric hydraulic cylinder provided in this application embodiment, the specific implementation process of the method for identifying off-center load before pressure holding of an electric hydraulic cylinder provided in this application embodiment will be described by way of example below.

[0046] Figure 3 This paper presents a schematic flowchart of an electro-hydraulic cylinder pre-pressure holding off-center load identification method according to an embodiment of the present application. The electro-hydraulic cylinder pre-pressure holding off-center load identification method includes: S100, determine the initial end face gap data formed between the two end face distance measurement areas and the external mounting reference in the initial state; wherein, the initial end face gap data is used to indicate the reference gap of each of the two end face distance measurement areas relative to the external mounting reference when the electric hydraulic cylinder has not entered the pressure holding test state.

[0047] The initial state can be understood as the stage where the electro-hydraulic cylinder has completed mechanical installation but has not yet entered the pressure holding test procedure, the hydraulic system has not yet been pressurized or has just been emptied, and the hydraulic cylinder is in a free state without load or only bearing its own weight and preload. The external mounting reference refers to the reference surface used for positioning and connection between the electro-hydraulic cylinder and the external driven component or fixed base during installation. The initial end face gap data refers to the distance values ​​between the two end face distance measurement areas and the external mounting reference in the initial state. These two distance values ​​constitute a set of reference data used to indicate the reference spatial position of the front end lug end face of the electro-hydraulic cylinder when there is no pressure holding load.

[0048] Specifically, after the electro-hydraulic cylinder has completed mechanical installation, hydraulic pipeline connection, and electrical wiring, but before the hydraulic oil pump is started to pressurize, the initial gap acquisition process can be automatically triggered: the controller sequentially reads or receives the distance signals output by the two laser displacement sensors corresponding to the two end face distance measurement areas in a pressure-free state, filters and denoises the acquired signals, and marks the two processed distance values ​​as the initial end face gap on the first side and the initial end face gap on the second side, respectively, while determining the timestamp and status. Alternatively, a manual initial data acquisition process can be used, where technicians send acquisition commands via the operation panel or mobile terminal after completing installation preparations. After receiving the command, the controller completes the acquisition, processing, and storage of the gap signals twice to obtain the initial end face gap data on both sides.

[0049] S200, when the electric hydraulic cylinder is in the pre-pressure holding test state, determines the two-sided state end face gap data formed between the two end face distance measurement areas and the external mounting reference; wherein, the two-sided state end face gap data is used to indicate the pre-pressure holding test gap of each of the two end face distance measurement areas relative to the external mounting reference when the electric hydraulic cylinder is in the pre-pressure holding test state.

[0050] It can be understood that the gap data of the two end faces refers to the distance values ​​between the two end face measurement areas and the external mounting reference in the pre-pressure holding test state. These two distance values ​​are used to indicate the actual spatial position of the front end face of the electro-hydraulic cylinder when it is about to enter the pressure holding test. The pre-pressure holding test state refers to the intermediate check state in which the electro-hydraulic cylinder has completed the gap measurement in the initial state, the hydraulic system has completed the pressure building or pre-pressure building, and the working chamber of the hydraulic cylinder has been filled with hydraulic oil and reached a certain pre-pressure (e.g., 10% to 30% of the rated working pressure or the pre-check pressure value set by the system), but has not yet officially entered the pressure holding test timing procedure.

[0051] For example, after confirming that the hydraulic system has completed pre-pressure building and the pressure is stable, the controller sequentially determines the distance signals output by the two displacement sensors corresponding to the two end face distance measurement areas in the pre-pressure holding test state, performs filtering and noise reduction processing, and marks the two processed distance values ​​as the first side state end face gap and the second side state end face gap, respectively. By obtaining the actual values ​​of the gaps on both sides of the end face in the pre-pressure holding test state, the off-center load response of the front ear end face after the hydraulic system pre-pressure building can be converted into a quantifiable gap change, avoiding the discovery of off-center load abnormality only after the pressure holding test has started.

[0052] In one possible implementation, please refer to Figure 4 , Figure 4 The document illustrates the specific steps for acquiring the gap data between the two end faces in the pre-pressure holding test state; S200, when the electric hydraulic cylinder is in the pre-pressure holding test state, the gap data between the two end face distance measurement areas and the external mounting reference is determined, including: S210, when the electric hydraulic cylinder is in the pre-pressure holding test state, determine the gap readings of the two side state end faces corresponding to the radially opposite end face distance measurement area; wherein, the pre-pressure holding test state includes the pre-inspection state before the pressure holding test.

[0053] It can be understood that the gap readings on both sides of the end face refer to the raw or pre-processed distance measurement values ​​directly read by the controller from the displacement sensors corresponding to the distance measurement areas of the two end faces. The test state before pressure holding includes the pre-check state before pressure holding test, that is, the hydraulic system has completed pre-pressure building, the working chamber of the hydraulic cylinder has reached the set pre-check pressure, and the system is in a state of waiting for the formal pressure holding test command.

[0054] For example, the controller reads the gap signal output by the displacement sensor in the pre-pressure holding test state through an analog-to-digital conversion interface or a digital communication bus (e.g., RS-485, CAN bus, or I²C bus). It performs moving average filtering or median filtering on multiple sampled values ​​of each sensor to remove instantaneous interference and measurement noise, obtaining two stable gap readings, which are recorded as the first side state end face gap reading and the second side state end face gap reading, respectively. In addition, if the end face distance measurement area is measured using a contact gauge, the controller can also receive readings manually input by technicians through a human-machine interface, thus separating data acquisition from data management and providing tamper-proof and traceable original measurement records for data processing.

[0055] S220, associate the gap readings of the two side end faces with the corresponding test states before pressure holding to obtain the gap data of the two side end faces.

[0056] Specifically, association refers to binding the gap readings of the two side state faces obtained in step S210 with the identification information of the current pre-pressure holding test state (such as status code, timestamp, system pressure value, pre-pressure building completion flag, etc.) to form a set of data structures with complete information. After receiving the gap readings of the two side state faces, the controller reads the current pre-pressure holding test state flag bit and the current system pressure value from the system status register, and determines the two and the set of readings as a data record. The data record includes, for example, the gap value of the first side state face, the gap value of the second side state face, the measurement time, the system pressure, and the status flag.

[0057] This setup, by associating the gap reading with the test state before pressure holding, ensures that each gap data has a clear state context. This allows for accurate differentiation of measured values ​​under different states in subsequent data comparison and analysis, avoiding data comparison errors caused by state confusion and ensuring the reliability of the off-center load identification results.

[0058] S300, according to the correspondence between the two end face distance measurement areas, determines the end face gap change data based on the initial end face gap data and the state end face gap data on both sides respectively; among them, the end face gap change data is used to indicate the difference between the state end face gap before pressure holding and the initial end face gap.

[0059] It can be understood that the end face clearance change data refers to a dataset used to indicate the amount of change in the end face clearance before pressure holding relative to the initial end face clearance. This dataset includes the change in the first side end face clearance and the change in the second side end face clearance. A positive value indicates that the clearance on that side has increased, meaning that the end face on that side has moved away from the external mounting reference; a negative value indicates that the clearance on that side has decreased, meaning that the end face on that side has moved closer to the external mounting reference; a clearance change of zero or close to zero indicates that the clearance on that side has not changed significantly between the initial state and the test state before pressure holding.

[0060] For example, the controller, based on the initial end face gap data and the state end face gap data on both sides, pairs the first side state end face gap with the first side initial end face gap and the second side state end face gap with the second side initial end face gap according to the side correspondence relationship, and calculates the difference of each pairing. The change in the first side end face gap is equal to the first side state end face gap minus the first side initial end face gap, and the change in the second side end face gap is equal to the second side state end face gap minus the second side initial end face gap. The two changes are combined into end face gap change data. By calculating and recording the changes in the gaps on both sides separately, the independent information of the gap change on each side can be retained. This allows for the subsequent analysis of the off-center load direction and degree of off-center load to be judged by the magnitude and sign of the changes on both sides, rather than making a general judgment based solely on the overall trend of the changes on both sides. This improves the accuracy of off-center load direction identification and the precision of off-center load degree quantification.

[0061] In one possible implementation, please refer to Figure 5 , Figure 5 The following steps are shown to calculate the end face gap change based on the side correspondence relationship, using initial data and state data; S300, according to the correspondence relationship between the two end face ranging areas, the end face gap change data is determined based on the initial end face gap data and the state end face gap data on both sides, including: S310, based on the side correspondence relationship of the end face distance measurement area, the first side data in the initial end face gap data on both sides is matched with the same side data in the state end face gap data on both sides, and the second side data in the initial end face gap data on both sides is matched with the other same side data in the state end face gap data on both sides.

[0062] For example, the controller assigns a unique side identification identifier to each end-face ranging area by reading the sensor's hardware address, communication node ID, or preset channel number. For instance, a side identification identifier of 0 represents the first side, and a side identification identifier of 1 represents the second side. When performing data mapping, the controller iterates through each record in the initial end-face gap data on both sides, searches for records with the same side identification identifier in the state end-face gap data on both sides based on its side identification identifier, and establishes a corresponding link between the two. If both datasets contain complete side identification information and the side identification identifiers are consistent, the mapping relationship is established directly. If there is missing or ambiguous side identification information in the datasets, the controller can perform fault tolerance processing according to preset default mapping rules. For example, the default mapping rules correspond sequentially according to the data storage order, and generate a mapping relationship confirmation prompt for technical personnel to review.

[0063] Therefore, by strictly matching data one-to-one based on the side correspondence, the calculation of the gap change on each side can use initial data and state data from the same physical location, eliminating calculation errors caused by side confusion.

[0064] S320, the difference between the end face gap before pressure holding and the corresponding initial end face gap in the first side data after corresponding, and the difference between the end face gap before pressure holding and the corresponding initial end face gap in the second side data after corresponding, are determined as end face gap change data.

[0065] Specifically, the controller can perform the following calculations sequentially: the change in the clearance of the first side end face is equal to the first side state end face clearance minus the first side initial end face clearance; the change in the clearance of the second side end face is equal to the second side state end face clearance minus the second side initial end face clearance. If the first side initial end face clearance is 2.50 mm and the first side state end face clearance is 2.10 mm, then the change in the clearance of the first side end face is -0.40 mm, indicating that the clearance on that side has decreased by 0.40 mm; if the second side initial end face clearance is 2.48 mm and the second side state end face clearance is 2.72 mm, then the change in the clearance of the second side end face is +0.24 mm, indicating that the clearance on that side has increased by 0.24 mm. The controller stores these two changes as end face clearance change data, while retaining the positive and negative signs to indicate the direction of change.

[0066] This setup, by calculating the gap changes on both sides separately and retaining the sign information, allows us to obtain not only the magnitude of the gap change but also the direction of change—the crucial information of whether it is increasing or decreasing. In the presence of eccentric loading, the gap on the eccentric side typically decreases, while the gap on the opposite side typically increases. This asymmetrical pattern of decrease on one side and increase on the other is a characteristic feature for determining the existence and direction of eccentric loading.

[0067] S400, based on the difference between the changes in the gap between the two end faces in the end face gap change data, determines the off-center load characterization data to characterize the degree of unevenness in the change of the gap between the two end faces.

[0068] It can be understood that the difference between the changes in the clearance between the two end faces in the end face clearance variation data refers to the absolute value of the difference between the changes in the clearance between the first and second end faces, or the square of the difference, or the degree to which the ratio of the two deviates from 1. This difference reflects the degree of asymmetry in the amplitude of the clearance changes on both sides. Off-center load characterization data refers to a dimensionless or dimensionlessly unified quantitative index obtained after normalizing or standardizing the degree of unevenness in the clearance changes between the two end faces. This index is used to uniformly measure the degree of off-center load at the front end of the electro-hydraulic cylinder under different specifications and installation clearance conditions.

[0069] For example, the controller first calculates the absolute difference between the changes in the first and second side end face gaps, i.e., the absolute value of the difference between the changes in the two side end face gaps. Then, it normalizes the absolute difference based on a determined reference gap scale, for example, by dividing the absolute difference by the reference gap scale to obtain dimensionless off-center load characterization data. The larger the reference gap scale, the larger the allowable installation gap for this model of electric hydraulic cylinder. The corresponding normalized off-center load characterization data will show a smaller value for the same absolute difference, thereby eliminating the influence of differences in installation gap size on the off-center load evaluation results of different models of electric hydraulic cylinders. This allows the off-center load judgment standard to be set uniformly, without having to set different absolute gap difference thresholds for each model, thus improving the universality and standardization of the method.

[0070] In one possible implementation, please refer to Figure 6 , Figure 6 The specific steps for determining normalized off-center load characterization data based on the difference in changes on both sides are shown; S400, based on the difference between the changes in the end face gaps on both sides in the end face gap change data, off-center load characterization data for characterizing the degree of unevenness in the changes in the end face gaps on both sides is determined, including: S410 determines a reference gap size greater than zero based on the initial end face gap data on both sides, or calls a preset reference gap size greater than zero determined by a sample of the same model, assembly specification or test reference.

[0071] Specifically, the reference clearance scale refers to a reference scale value used to normalize the difference in clearance variation between the two end faces. The controller can obtain the reference clearance scale in one of two ways: First, it can be dynamically determined, i.e., the reference clearance scale is calculated based on the initial end face clearance data obtained from the current electro-hydraulic cylinder, for example, taking the average, maximum, or minimum value of the initial end face clearance as the reference clearance scale; second, it can be preset, i.e., calling pre-stored reference clearance data from the controller. This reference clearance data can be a typical initial clearance value determined through statistical analysis in type testing of the same model sample, a nominal installation clearance value specified in the design drawings or assembly specifications, or a reference clearance value specified in industry testing standards.

[0072] By providing two methods for obtaining the reference gap scale—dynamic determination and preset recall—it can meet the needs of different application scenarios. In the single-piece testing or sample evaluation stage, the dynamic determination method can automatically adapt to the actual installation gap of each device without manual configuration. In the mass production line testing stage, the preset method can ensure that the off-center load evaluation of all devices of the same model is based on a unified reference scale, improving the consistency and comparability of the evaluation results.

[0073] S420, the off-center load characterization data is obtained by processing the end face gap variation data according to the reference gap scale.

[0074] It should be explained that processing the end face gap change data refers to calculating or transforming the output end face gap change amount using a determined reference gap scale.

[0075] For example, the controller calculates the difference between the two side load characterization data based on a determined reference gap size, such as 2.49 mm, and the obtained gap variation on both sides, such as -0.40 mm on the first side and +0.24 mm on the second side. The absolute value is 0.64 mm. The off-center load characterization data is equal to 0.64 mm divided by 2.49 mm, which is approximately equal to 0.257 or expressed as 25.7%. The off-center load characterization data can also be calculated as the absolute value of the difference between the ratios of the changes on both sides relative to the reference gap size, or as the sum of the squares of the changes on both sides divided by the square of the reference gap size, etc. The embodiments of this application do not limit this.

[0076] This setup, by normalizing the end face gap variation data to a reference gap scale, eliminates the problem that absolute differences under different installation gap conditions cannot be directly compared. It makes the off-center load characterization data a standardized evaluation index decoupled from the specific installation gap, which is convenient for horizontal comparison and statistical analysis between the same production line or equipment of the same model. It is also beneficial for setting a unified off-center load warning threshold.

[0077] S500 analyzes the off-center load characterization data and combines it with the trend of the gap change on both sides indicated in the end face gap change data to obtain the off-center load identification data before the pressure holding test; the off-center load identification data includes off-center load direction data determined based on the magnitude relationship of the gap change on both sides and off-center load degree data determined based on the difference in the gap change on both sides.

[0078] It can be understood that the off-center load direction data is used to indicate which side the front earring end face has been tilted off-center, that is, the direction of the off-center load tilt in the radial plane is determined based on the magnitude of the change in the gap between the two end faces; the off-center load degree data is used to indicate the severity of the off-center load, that is, the off-center load tilt angle or level is determined based on the magnitude of the difference in the change in the gap between the two end faces.

[0079] For example, after receiving the off-center load characterization data and the end face gap change data, the controller performs component decomposition on the off-center load characterization data, extracts the signs of the gap changes on both sides from the end face gap change data, and finally makes a comprehensive judgment by combining the relationship between the magnitude of the components and the sign information. That is, if the gap on the first side decreases (the change is negative) and the gap on the second side increases (the change is positive), and the off-center load component on the first side is greater than the off-center load component on the second side, the off-center load direction is determined to be towards the first side, and the off-center load degree is the overall off-center load degree value.

[0080] This setup, by combining the analysis of off-center load characterization data with the sign analysis of the changing trend of the gap on both sides, can not only provide the overall severity of the off-center load, but also the specific direction of the off-center load, providing technicians with complete off-center load diagnostic information, enabling technicians to adjust the installation posture of the electric hydraulic cylinder in a targeted manner.

[0081] In one possible implementation, please refer to Figure 7 , Figure 7 The specific steps for analyzing off-center load characterization data and combining it with the changing trend to obtain off-center load identification results are shown; S500, the off-center load characterization data is analyzed, and combined with the changing trend of the two-sided gap indicated in the end face gap change data, the off-center load identification data before the pressure holding test is obtained, including: S510, based on the independent characteristics of the off-center load characterization data corresponding to the two end face distance measurement areas, determine the first side off-center load component and the second side off-center load component; wherein, the first side off-center load component and the second side off-center load component correspond to the side where the two end face distance measurement areas are located, and the sum of the values ​​of the first side off-center load component and the second side off-center load component is used to characterize the overall off-center load degree.

[0082] For example, the first-side off-center load component refers to the off-center load contribution value of the measurement results in the first-side end face distance measurement area, and the second-side off-center load component refers to the off-center load contribution value of the measurement results in the second-side end face distance measurement area. Specifically, the total change can be calculated by summing the absolute values ​​of the changes in the first-side clearance and the absolute values ​​of the changes in the second-side clearance. The first-side eccentric load component is equal to the eccentric load characterization data (e.g., 0.257) multiplied by the percentage of the absolute value of the first-side clearance change in the total change. For example, it could be... ,Right now The second-side eccentric load component is equal to the eccentric load characterization data multiplied by the percentage of the absolute value of the second-side clearance change in the total change. For example, it could be 0.24 / 0.64 = 0.375. ,verify The overall off-center load characterization data proves that the decomposition is correct.

[0083] S520, extract the first side gap change symbol and the second side gap change symbol from the end face gap change data; wherein, the first side gap change symbol and the second side gap change symbol respectively indicate the direction of increase or decrease of the end face gap in the pre-pressure holding state of the corresponding side relative to the initial end face gap.

[0084] For example, the controller determines the change in the gap on the first side (e.g., -0.40 mm) and the change in the gap on the second side (e.g., +0.24 mm) from the end-face gap change data, and extracts their positive and negative signs respectively. The sign of the change in the gap on the first side is negative, indicating that the gap on the first side has decreased; the sign of the change in the gap on the second side is positive, indicating that the gap on the second side has increased. If the change on a certain side is exactly zero, the sign of the change in the gap on that side is recorded as no change. By explicitly extracting the signs of the gap changes on both sides, the physical meaning of the changing trend can be introduced into the determination of the off-center load direction. Under off-center load conditions, the side pointing to the off-center load direction shows a decrease in gap because the end face of the front ear is pressed towards the external mounting reference, while the opposite side shows an increase in gap because the end face is raised. This can avoid the single-dimensional judgment bias caused by relying solely on the magnitude of the off-center load component.

[0085] S530, based on the numerical relationship between the first side eccentric load component and the second side eccentric load component, and combined with the sign of the first side clearance change and the sign of the second side clearance change, the side with the larger eccentric load component and the clearance change sign indicating a decrease in clearance is determined as the eccentric load direction data, and the overall eccentric load degree is determined as the eccentric load degree data.

[0086] Specifically, for example, the calculation results of steps S510 and S520 can be used as an example: the first-side eccentric load component is 0.161, and the second-side eccentric load component is 0.096. The first-side eccentric load component is greater than the second-side eccentric load component, so it is initially determined that the eccentric load is more closely related to the first side; the sign of the gap change on the first side is negative, that is, the gap decreases, which meets the condition for confirming the eccentric load direction. Therefore, the eccentric load direction data is determined to be that the eccentric load direction points to the first side; the overall eccentric load degree is... The controller determines the load level based on preset thresholds. For example, a load level less than 0.1 is considered normal, 0.1 to 0.3 is considered mild load, 0.3 to 0.5 is considered moderate load, and greater than 0.5 is considered severe load. The current value of 0.257 falls within the mild load range, so the load level data is considered mild load. The controller combines the load direction data and the load level data into the final load identification data and outputs it through the human-machine interface or communication interface.

[0087] This setup, by cross-verifying the magnitude of the off-center load component with the directional information of the gap change sign, enables a dual confirmation mechanism. It requires that the side with the larger off-center load component conforms to the off-center load direction judgment, and that the gap change sign on that side is consistent with the physical law of off-center load. This effectively filters out misjudgments caused by sensor drift, local defects on the mounting surface, or measurement noise, significantly improving the accuracy of off-center load direction identification and the reliability of off-center load degree assessment.

[0088] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0089] This application also provides a controller. Figure 8 This is a schematic diagram of the controller provided in one embodiment of this application. Figure 8 As shown, the controller 7 in this embodiment includes: at least one processor 70 ( Figure 8 Only one is shown in the image), at least one memory 71 ( Figure 8 (Only one is shown in the image) and a computer program 72 stored in the at least one memory 71 and executable on the at least one processor 70, wherein when the processor 70 executes the computer program 72, it causes the controller 7 to perform the steps in any of the above-described electro-hydraulic cylinder embodiments, or causes the controller 7 to perform the functions of each module / unit in the above-described system embodiments.

[0090] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such 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 this application, and should all be included within the protection scope of this application.

Claims

1. An electric hydraulic cylinder, characterized in that, include: DC motor, including power output unit; The hydraulic oil pump has a power input unit that is drively connected to the power output unit, and the hydraulic oil pump is disposed on the power output side of the DC motor; A hydraulic cylinder is arranged along the extension and retraction direction of the electric hydraulic cylinder; the working chamber of the hydraulic cylinder is connected to the oil outlet of the hydraulic pump through a hydraulic oil circuit. The front earring is located on the side of the hydraulic cylinder away from the DC motor and the hydraulic pump; A rear end earring is provided, which is positioned opposite to the front end earring along the extension and retraction direction of the electric hydraulic cylinder, and the rear end earring is located at one end of the hydraulic cylinder near the DC motor and the hydraulic pump; the DC motor and the hydraulic pump are located on one side of the hydraulic cylinder and near the rear end earring, and the hydraulic pump is located between the oil circuit connection area of ​​the DC motor and the hydraulic cylinder. as well as An end face deviation limiting calibration component is disposed on the end face side of the front earring. The end face deviation limiting calibration component includes a positioning part that cooperates with the positioning of the front earring and two end face distance measuring areas arranged opposite to each other along the radial direction of the front earring.

2. The electric hydraulic cylinder as described in claim 1, characterized in that, The positioning part abuts against the hole wall or the edge of the hole of the front earring to limit the radial displacement of the end face deviation check member relative to the front earring.

3. The electric hydraulic cylinder as described in claim 1, characterized in that, The radially opposite end face ranging areas are arranged symmetrically with respect to the central axis of the front earring.

4. The electric hydraulic cylinder as described in claim 1, characterized in that, The hydraulic cylinder is equipped with a pressure holding valve; the pressure holding valve is located at the connection between the working chamber of the hydraulic cylinder and the hydraulic circuit, and the opening direction of the pressure holding valve is from the hydraulic circuit to the working chamber.

5. The electric hydraulic cylinder as described in claim 4, characterized in that, The pressure holding valve maintains a pressure greater than the sum of the preset pressure holding test pressure and the preset safety margin in the direction opposite to the opening direction.

6. The method for identifying off-center load before pressure holding in an electro-hydraulic cylinder as described in any one of claims 1 to 5, characterized in that, The method includes: Determine the initial end face gap data formed between the two end face ranging regions and the external mounting reference in the initial state; wherein, the initial end face gap data is used to indicate the reference gap between each of the two end face ranging regions and the external mounting reference when the electric hydraulic cylinder has not entered the pressure holding test state; When the electric hydraulic cylinder is in the pre-pressure holding test state, determine the two-sided state end face gap data formed between the two end face distance measurement areas and the external mounting reference; wherein, the two-sided state end face gap data is used to indicate the pre-pressure holding test gap of each of the two end face distance measurement areas relative to the external mounting reference when the electric hydraulic cylinder is in the pre-pressure holding test state. Based on the correspondence between the two end face ranging areas, the end face gap change data is determined according to the initial end face gap data on both sides and the state end face gap data on both sides; wherein, the end face gap change data is used to indicate the difference between the state end face gap before pressure holding and the initial end face gap; Based on the difference between the changes in the gap between the two end faces in the end face gap change data, off-center load characterization data is determined to characterize the degree of unevenness in the change of the gap between the two end faces. The off-center load characterization data is analyzed, and combined with the trend of the gap change on both sides indicated in the end face gap change data, off-center load identification data before pressure holding test is obtained; wherein, the off-center load identification data includes off-center load direction data determined based on the magnitude relationship of the gap change on both sides and off-center load degree data determined based on the difference in the gap change on both sides.

7. The method as described in claim 6, characterized in that, When the electric hydraulic cylinder is in the pre-pressure holding test state, the determination of the two end face gap data formed between the two end face distance measurement areas and the external mounting reference includes: When the electric hydraulic cylinder is in the pre-pressure holding test state, determine the gap readings of the two side state end faces corresponding to the radially opposite end face distance measurement areas; wherein, the pre-pressure holding test state includes the pre-pressure holding test pre-inspection state; The gap readings of the two side end faces are correlated with the corresponding test states before pressure holding to obtain the gap data of the two side end faces.

8. The method as described in claim 6, characterized in that, The step of determining end-face gap change data based on the correspondence between the two end-face ranging regions and the initial end-face gap data and the state end-face gap data on both sides includes: Based on the side correspondence of the end face distance measurement area, the first side data in the initial end face gap data of both sides is matched with the same side data in the state end face gap data of both sides, and the second side data in the initial end face gap data of both sides is matched with the other same side data in the state end face gap data of both sides. The difference between the end face gap before pressure holding and the corresponding initial end face gap in the first side data, and the difference between the end face gap before pressure holding and the corresponding initial end face gap in the second side data, are determined as the end face gap change data.

9. The method as described in claim 6, characterized in that, The determination of off-center load characterization data based on the difference between the changes in the gaps on both sides of the end face in the end face gap change data, including: A reference gap size greater than zero is determined based on the initial end face gap data on both sides, or a preset reference gap size greater than zero is determined by calling the sample of the same model, assembly specifications or test reference. The off-center load characterization data is obtained by processing the end face gap variation data according to the reference gap scale.

10. The method as described in claim 6, characterized in that, The process of analyzing the off-center load characterization data and combining it with the trend of gap change on both sides indicated in the end face gap change data yields off-center load identification data before the pressure holding test, including: Based on the independent characteristics of the off-center load characterization data corresponding to the two end face distance measurement areas, a first side off-center load component and a second side off-center load component are determined; wherein, the first side off-center load component and the second side off-center load component respectively correspond to the side where the two end face distance measurement areas are located, and the sum of the values ​​of the first side off-center load component and the second side off-center load component is used to characterize the overall off-center load degree. Extract the first side gap change symbol and the second side gap change symbol from the end face gap change data; wherein, the first side gap change symbol and the second side gap change symbol respectively indicate the direction of increase or decrease of the end face gap in the pre-pressure holding state of the corresponding side relative to the initial end face gap; Based on the numerical relationship between the first side off-center load component and the second side off-center load component, and combined with the analysis of the first side clearance change sign and the second side clearance change sign, the side with the larger off-center load component and the clearance change sign indicating a decrease in clearance is determined as the off-center load direction data, and the overall off-center load degree is determined as the off-center load degree data.

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