Valve calibration system and calibration method

Abstract

Problem: In order to achieve improvement in work efficiency and improvement in calibration accuracy of calibration work, when a valve operated by current applied to an electric actuator opens a flow passage, at calibration of a current value at a valve opening position, control is performed so that time taken for increasing a scan of applied current becomes substantially constant. Solution: A predicted value calculation device (24) is provided for predicting a calibration value of a valve opening position current value based on information about the valve opening position current value, and a scan start current value (iS) is set so that time taken for increasing a scan from a scan start to a predicted value (iE) predicted by the predicted value calculation device (24) becomes a fixed time (T).

Description

Technical Field

[0001] This invention relates to the technical field of valve calibration systems and calibration methods, where the valve is installed in the hydraulic circuit of a working machine such as a hydraulic excavator. Background Technology

[0002] Typically, the hydraulic circuit of a working machine such as a hydraulic excavator may include a valve configured to open and close flow passages based on the current arriving at the electro-actuator. In cases where such a valve (e.g., a control valve) is configured to control the supply / discharge of oil to / from hydraulic actuators (e.g., boom cylinders, stick cylinders, etc.) within the hydraulic excavator, and the solenoid proportional valve is configured to output pilot pressure to actuate the control valve (which is an electro-actuator), current is applied to the solenoid proportional valve according to the operation of the tool by each hydraulic actuator, causing the solenoid proportional valve to output pilot pressure, and the control valve to open the flow passage to the hydraulic actuator. However, the current value applied to the solenoid proportional valve when the control valve opens the flow passage (valve open position current value) depends not only on the individual differences (manufacturing tolerances) of the solenoid proportional valve, but also on the opening characteristics of the control valve or the circuit configuration in which the control valve is arranged. Furthermore, the valve open position current value also changes due to the aging and degradation of components of the solenoid proportional valve and the control valve. Therefore, it is necessary to calibrate the valve open position current value using valves installed in the hydraulic circuit of the working machine.

[0003] As a method for calibrating the valve open position current value, a technique is known in the past to measure the pressure change at the valve inlet side while increasing the current applied to the electric actuator under the condition that a fixed hydraulic pressure is supplied to the valve inlet side, and to determine the calibration value of the valve open position current value (crack point current command) based on the measured pressure change (see, for example, Patent Document 1).

[0004] Existing technical documents

[0005] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent No. 5281573 Summary of the Invention

[0007] [The problem this invention aims to solve]

[0008] Furthermore, as disclosed in Patent Document 1, when calibrating the valve opening position current value by simultaneously increasing the applied current to the electric actuator while measuring pressure, there is a problem of time-consuming calibration work, resulting in low work efficiency when increasing the applied current from the point of zero. Therefore, it is recommended to preset the scan initiation current value to start increasing the scan, rapidly increase the current from the current value of zero to the scan initiation current value, and increase the applied current at a predetermined rate suitable for starting the scan from the scan initiation current value. However, many valves are configured similarly to the hydraulic circuits installed in hydraulic excavators. When calibrating these many valves, if the scan initiation current value is set uniformly, as mentioned above, even when using the same type of electric actuator, the valve opening position current value varies not only depending on the individual differences of the electric actuator but also on various conditions such as the opening characteristics of the valve and the circuit, resulting in differences between scan times until the valve opening position current value is reached from the scan initiation current value. If this difference between the scan times from the scan initiation current value to reaching the valve opening position current value is large, there is a problem of variations in the working conditions of the calibration work, which hinders the standardization of the work and the improvement of accuracy. In these respects, there are problems that the present invention aims to solve.

[0009] [Problem-solving methods]

[0010] In view of the above-mentioned practical situation, the object of the present invention is to solve these problems. According to claim 1 of the present invention, in a hydraulic circuit of a machine including a valve, the valve is configured to operate according to a current applied to an electric actuator to open and close a flow passage, a valve calibration system is configured to calibrate a valve open position current value applied to the electric actuator when the valve opens the flow passage, and the valve calibration system includes: a calibration value prediction device for predicting a calibration value of the valve open position current value based on information about the valve open position current value; a scan start current value setting unit for setting a scan start current value; a hydraulic supply device for supplying hydraulic pressure at a fixed pressure to the inlet side of the valve; and an applied current control device for initiating the application of current to the electric actuator to increase the current. The scan starts at the current value and further scans the applied current value of the electric actuator at a predetermined rate from the scan starts at the current value; and a pressure measuring device for measuring pressure changes on the inlet or outlet side of the valve during the application of current to the electric actuator, wherein the pressure measuring device is configured to obtain a calibration value of the valve open position current value based on the applied current value at the pressure change measured by the pressure measuring device, and wherein the scan starts at the current value setting device sets the scan starts at the current value based on the predicted value, such that the time taken to increase the scan from the scan start to the predicted value predicted by the calibration value prediction device becomes a preset fixed time.

[0011] The valve calibration system according to claim 2 of the present invention is the valve calibration system according to claim 1, wherein the calibration value prediction device includes at least one of the following: calibration information of past valve open position current values, manufacturing information of the electric actuator and valve, information of the machine using the valve, and information of the location where the machine can operate, as information about the valve open position current value required for the calibration value to predict the valve open position current value.

[0012] The valve calibration system according to claim 3 of the present invention is the valve calibration system according to claim 1 or 2, wherein information about the valve open position current value is accumulated as big data in a server, and a calibration value prediction device provided in the server predicts the calibration value of the valve open position current value based on the result of trend analysis of the big data.

[0013] According to claim 4 of the present invention, in a hydraulic circuit of a machine including a valve configured to operate to open and close a flow passage based on a current applied to an electric actuator, a valve calibration method is provided for calibrating a valve open position current value applied to the electric actuator when the valve opens the flow passage, the valve calibration method comprising the steps of: predicting a calibration value of the valve open position current value based on information about the valve open position current value; setting a scan initiation current value; supplying a fixed hydraulic pressure to the inlet side of the valve; initiating a scan of the current applied to the electric actuator to increase the current to the scan initiation current value, and further increasing the current applied to the electric actuator from the scan initiation current value at a predetermined rate; measuring a pressure change on the inlet side or outlet side of the valve during the application of current to the electric actuator; and obtaining a calibration value of the valve open position current value based on the current value applied at the measured pressure change, wherein the scan initiation current value is set according to a predicted value such that the time taken to increase the scan from the start of the scan to the predicted value of the calibration value of the predicted valve open position current value becomes a preset fixed time.

[0014] [Advantages of the Invention]

[0015] According to the invention of claims 1 and 4, the time spent scanning the applied current required for calibrating the valve opening position current value can be kept substantially constant, thereby enabling the standardization of calibration work and contributing to improved work efficiency and calibration accuracy.

[0016] According to the invention of claim 2, highly accurate predicted values ​​can be obtained.

[0017] According to the invention of claim 3, a predicted value with high accuracy can be obtained reliably. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the hydraulic circuit of a hydraulic excavator.

[0019] Figure 2 This is a block diagram showing the construction of the calibration control unit.

[0020] Figure 3 This is a flowchart illustrating the calibration control process.

[0021] Figure 4 This is a graph showing the scan time from the scan start current value to the predicted value.

[0022] Figure 5 It is a graph showing the relationship between valve inlet side pressure (or outlet side pressure), valve core displacement, and applied current value.

[0023] Figure 6 This is a diagram showing the server's input / output. Detailed Implementation

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 A schematic diagram of the hydraulic circuit of a hydraulic excavator, used as an example of a working machine, is shown. Figure 1 In the attached figure, reference numeral 1 indicates a hydraulic pump; 1a indicates a capacity changing device for hydraulic pump 1; 2 indicates a discharge line for hydraulic pump 1; 3 indicates an oil tank; 4 indicates a hydraulic cylinder; 5 indicates a pilot control valve configured to perform oil supply / discharge control to / from hydraulic cylinder 4; and 6A and 6B indicate a first and a second electromagnetic proportional valve that output pilot pressure to control valve 5.

[0025] In this embodiment, control valve 5 corresponds to the valve of the present invention, and the first electromagnetic proportional valve 6A and the second electromagnetic proportional valve 6B correspond to the electric actuators of the present invention. Furthermore, the hydraulic excavator is equipped with various hydraulic actuators, such as boom cylinders, stick cylinders, bucket cylinders, travel motors, and swivel motors, and is equipped with control valves corresponding to each hydraulic actuator, and also with electromagnetic proportional valves configured to output pilot pressure to actuate each control valve. However, in Figure 1 In the diagram, only one hydraulic cylinder 4 is shown as a representative of these hydraulic actuators, control valves, and solenoid proportional valves, along with a control valve 5 corresponding to the hydraulic cylinder 4, first and second solenoid proportional valves 6A and 6B corresponding to the control valve 5, and two other control valves 7 corresponding to the other two hydraulic actuators (not shown).

[0026] The control valve 5 comprises a valve core including a first pilot port 5a and a second pilot port 5b. When no pilot pressure is input to the first pilot port 5a and the second pilot port 5b, the control valve 5 is located in an intermediate position N, in which the supply flow passage from the hydraulic pump 1 to the hydraulic cylinder 4 and the discharge flow passage from the hydraulic cylinder 4 to the oil tank 3 are closed. However, the control valve 5 is configured such that, by a pilot pressure input from the first electromagnetic proportional pressure reducing valve 6A or the second electromagnetic proportional valve 6B to the first pilot port 5a or the second pilot port 5b, it moves to a first operating position X or a second operating position Y. In the first operating position X or the second operating position Y, the supply flow passage 5c from the hydraulic pump 1 to the hydraulic cylinder 4 and the discharge flow passage 5d from the hydraulic cylinder 4 to the oil tank 3 are opened to perform supply flow control and discharge flow control of the hydraulic cylinder 4.

[0027] In addition, Figure 1In the attached drawing, reference numeral 8 denotes an on-board controller. The controller 8 receives an operation signal from an operation detection device 9A that detects the operation direction and amount of the operating tool (operating lever, operating pedal, etc.) 9 used to detect the operation of the hydraulic cylinder 4, and applies current as a control signal to the first electromagnetic proportional valve 6A and the second electromagnetic proportional valve 6B in response to the input signal. Then, as described above, by increasing or decreasing the pilot pressure according to the applied current value output from the first electromagnetic proportional valve 6A and the second electromagnetic proportional valve 6B, the control valve 5 is adapted to shift from the intermediate position N to the first operating position X or the second operating position Y to perform supply flow control and discharge flow control of the hydraulic cylinder 4.

[0028] As described below, during calibration work when the operating tools are not in operation, the controller 8 applies current to the first electromagnetic proportional valve 6A and the second electromagnetic proportional valve 6B. Additionally, the hydraulic excavator is equipped with operating tools for operating hydraulic actuators other than the hydraulic cylinder 4, and an operation detection device for detecting the operation of these operating tools. Figure 1 Only the operating tool 9 and the operating detection device 9A for the hydraulic cylinder 4 are shown in the diagram.

[0029] In addition, Figure 1 In the attached drawing, reference numeral 10 indicates a relief valve for controlling the discharge flow from hydraulic pump 1 to oil tank 3. In response to a control signal from controller 8, and based on an increase in the amount of operation of the operating tool 9 for the hydraulic cylinder and the operating tools for other hydraulic actuators, relief valve 10 operates to reduce the discharge flow (including zero discharge flow). As described below, controller 8 actuates relief valve 10 when the operating tools are not operated during calibration work.

[0030] Next, we will refer to Figures 2 to 5 The calibration system and calibration method of the present invention are described as follows: as an example, when the control valve 5 is moved from the intermediate position N to the first operating position X to open the supply flow channel 5c from the hydraulic pump 1 to the hydraulic cylinder 4, a calibration operation is performed to calibrate the valve opening position current value, which is the current value applied to the first electromagnetic proportional valve 6A.

[0031] First, the controller 8 is equipped with a calibration control unit 11, which is configured to automatically calibrate the current value at the valve opening position. For example... Figure 2As shown, a pressure sensor 12 for detecting the pressure of the discharge line 2 of the hydraulic pump 1 is connected to the input side of the calibration control unit 11, and the first electromagnetic proportional valve 6A and the second electromagnetic proportional valve 6B, the capacity changing device 1a of the hydraulic pump 1, and the relief valve 10 are connected to the output side of the calibration control unit 11. Furthermore, the calibration control unit 11 is configured to allow an external controller 13 (such as a personal computer detachably connected to the controller 8) to be connected thereto for free input and output, and includes a predictive value reading unit 14, a scan start current value setting unit 15, a pump pressure control unit 16 and an applied current control unit 17, a pressure measurement unit 18, a current value calibration unit 19, etc. Figure 2 Only the parts related to the calibration control unit 11 among the various controls executed by the controller 8 are shown. In addition, not only the first electromagnetic proportional valve 6A and the second electromagnetic proportional valve 6B, but also various electric actuators to be calibrated (e.g., electromagnetic proportional valves that output pilot pressure to another control valve 7, etc.) are connected to the output side of the calibration control unit 11, but these are also omitted here.

[0032] The external controller 13 is now equipped with a display device such as a monitor and an operating device such as a keyboard and touch panel, and is connected to the server 20 as described below. The external controller 13 is adapted to obtain a predicted value iE of the calibration value of the valve opening position current from the server 20; and can perform actions such as initiating automatic calibration by the calibration control unit 11 and selecting the electric actuator to be calibrated via the operating device of the external controller 13. The server 20 can be connected to the controller 8 via a communication device such as the Internet instead of the external controller 13, and the controller 8 can have equivalent functionality to the external controller 13.

[0033] Furthermore, during the calibration of the current value at the valve opening position, as a preliminary preparation, the pressure on hydraulic cylinder 4, which is supplied with pressurized oil from control valve 5, is released, and this hydraulic cylinder 4 is calibrated. In this case, pressure release can be performed manually, but if a function to release pressure by automatically moving the valve core of control valve 5 is pre-configured, this is effective when it is assumed to be integrated into the continuous calibration process. Additionally, the hydraulic oil temperature during calibration is manually or automatically controlled to maintain a predetermined temperature range.

[0034] Next, we will refer to Figure 3 The flowchart describes the control of the automatic calibration operation performed by the calibration control unit 11.

[0035] First, when an operation signal for starting calibration is input from the external controller 13, after necessary initial settings are performed, control commands are output from the pump pressure control unit 16 to the capacity changing device 1a of the hydraulic pump 1 and the relief valve 10, and the discharge pressure of the hydraulic pump 1 is maintained at a preset fixed pressure. As a result, a fixed hydraulic pressure is supplied to the inlet side of the control valve 5 (step S1). The hydraulic pump 1 constitutes the hydraulic supply device of the present invention.

[0036] Furthermore, based on the pressure measurement value of the discharge line 2 input from the pressure sensor 12, the pressure change on the inlet side of the control valve 5 is monitored by the pressure measurement unit 18 (step S2). Monitoring of pressure changes continues until the calibration process is complete. The pressure sensor 12 constitutes the pressure measurement device of the present invention.

[0037] Subsequently, the prediction value reading unit 14 performs the reading of the prediction value iE (step S3). The prediction value iE is the current calibration value of the predicted valve opening position current value of the first electromagnetic proportional valve 6A, and is provided by the server 20 via the external controller 13, but the prediction value iE provided by the server 20 will be described below.

[0038] Subsequently, the scan start current value setting unit 15 performs the setting of the scan start current value iS (step S4). The scan start current value iS is the current value when the scan of the applied current increases as described below begins, and the setting value of the scan start current value iS is set according to the predicted value iE, such that the time taken from the start of the scan to the predicted value iE reaching the scan increase becomes a preset fixed time T. In this case, the scan start current value iS is calculated by calculating the change in the current value within the fixed time T from the rate of increase of the current value during the scan, and subtracting the change from the predicted value iE. Meanwhile, as... Figure 4 As shown, even if the predicted values ​​iE have different values ​​iE-1 and iE-2, the scanning time from the scan start current values ​​iS-1 and iS-2 to the predicted values ​​iE-1 and iE-2 is controlled to be a fixed time T. The scan start current value setting unit 15 constitutes the scan start current value setting device of the present invention.

[0039] Subsequently, the current application control unit 17 begins to apply current to the first electromagnetic proportional valve 6A. In this case, the current application control unit 17 increases the current from the current value 0 to the scan start current value iS at a fast rate (faster than the scan rate) (step S5), and after reaching the scan start current value iS, the applied current is scanned so that it increases at a predetermined constant rate suitable for scanning (step S6).

[0040] Since the span from the current value 0 to the scan start current value iS is outside the span of the current value at the predicted valve open position under current calibration, the applied current increases rapidly to shorten the calibration operation time. Furthermore, the applied current control unit 17 constitutes the applied current control device of the present invention.

[0041] As the applied current scan increases, the current value calibration unit 19 determines whether the pressure change at the inlet side of the control valve 5 is confirmed by the pressure measurement unit 18 (step S7). Then, if no pressure change is confirmed, the applied current scan continues to increase. On the other hand, if a pressure change is confirmed, the current value calibration unit 19 applies the current value iC, which is determined to be the valve open position current value at the time of the pressure change, and updates the valve open position current value with the current calibration value iC (step S8), thereby completing the calibration of the first electromagnetic proportional valve 6A. Subsequently, in the same manner, the calibration of the second electromagnetic proportional valve 6B and the electric actuators configured to actuate other valves (e.g., electromagnetic proportional valves configured to output pilot pressure to other control valves 7) is adapted to be performed sequentially.

[0042] Now, Figure 5 The relationship between the inlet-side pressure of control valve 5 (measured by pressure sensor 12), the spool movement of control valve 5, and the current applied to the first electromagnetic proportional valve 6A during steps S5 to S8 is shown. Figure 5 As shown, when the scan of the current applied to the first electromagnetic proportional valve 6A increases from the scan start current value iS, the valve core of the control valve 5 begins to move and reaches the valve open position where the supply flow channel 5c is open. Then, when the valve core reaches the valve open position, the pressure on the inlet side of the control valve 5 suddenly decreases, and when the pressure begins to decrease, the applied current value is determined as the calibration value iC of the valve open position current value.

[0043] In this embodiment, the calibration value iC of the valve open position current is obtained from the inlet side pressure of the control valve 5, but as described... Figure 5 As shown by the dashed line, the correction value iC for the valve opening current can also be obtained by measuring the pressure change on the outlet side of control valve 5.

[0044] In this embodiment, the applied current value when the inlet pressure of control valve 5 begins to decrease is set as the valve open position current value. However, when the inlet pressure of control valve 5 begins to decrease, the current value after offset calibration from the applied current value can also be used as the valve open position current value. In this case, the offset correction amount is appropriately set according to the valve opening characteristics, the load applied to the hydraulic actuator supplying pressurized oil from the valve, the circuit structure, etc.

[0045] Next, the server 20, configured to provide a predicted value iE of the calibration value for the valve open position current value, will be described. (See figure for reference.) Figure 6 Various information from database 21 (accumulating calibration data of past valve opening position current values), manufacturer terminal 22 of electromagnetic proportional valves 6A, 6B and control valve 5, manufacturer terminal 23 of the machine using control valve 5 (hydraulic excavator in this embodiment), etc., are input to server 20, and on-site information (atmospheric temperature, atmospheric pressure, etc.) of the machine is input via external controller 13. In this case, the information input from manufacturer terminal 22 of control valve 5 and electromagnetic proportional valves 6A, 6B includes, for example, manufacturing site environment (atmospheric temperature, etc.), specifications, and batch or individual transport inspection information. The information input from manufacturer terminal 23 of the machine includes, for example, manufacturing site environment, specifications, hydraulic oil type, batch or individual transport inspection information, aging information, etc.

[0046] Then, the server 20 accumulates various input information into big data related to the calibration of the valve opening position current value. After a learning period, the prediction value calculation device (corresponding to the calibration value prediction device of the present invention) 24 installed in the server 20 performs trend analysis on the big data and predicts the calibration value of the valve opening position current value for each electric actuator installed in the hydraulic excavator based on the analysis results. Then, during the calibration operation of each electric actuator, the prediction result is provided to the vehicle controller 8 as the predicted value iE of the calibration value of the valve opening position current value via the external controller 13.

[0047] In this embodiment constructed as described above, a calibration system is used, for example, to calibrate the valve opening position current value applied to the first electromagnetic proportional valve 6A (electro-actuator) when the control valve 5 (valve) in the hydraulic circuit of the hydraulic excavator opens the supply flow channel 5c. However, this calibration system includes a prediction value calculation device 24 for predicting a calibration value of the valve opening position current value based on information about the valve opening position current value, a scan start current value setting unit 15 configured to set a scan start current value iS, a hydraulic pump 1 for supplying hydraulic pressure at a fixed pressure to the inlet side of the valve, an applied current control unit 17, and a pressure sensor 12. The applied current control unit 17 is configured to begin applying current to the electro-actuator to increase the current to the scan start current value iS, and further increase the scan of the applied current value from the scan start current value iS to the electro-actuator at a predetermined rate. The pressure sensor 12 is used to measure the pressure change on the inlet side of the valve during the application of current to the electro-actuator, wherein the calibration value iC of the valve opening position current value will be obtained based on the applied current value at the pressure change measured by the pressure sensor 12. In the valve calibration system, the scan start current setting unit 15 sets the scan start current value iS according to the predicted value iE, so that the time taken to increase the scan from scan start to the predicted value iE predicted by the predicted value calculation device 24 becomes a preset fixed time T.

[0048] As described above, in this embodiment, based on the calibration of the valve opening position current value, a calibrated value for the valve opening position current value is predicted based on information about the valve opening position current value, and the scan start current value iS is set such that the time taken to increase the scan from the start of the scan to the predicted value iE becomes a fixed time T according to iE. In this case, because the predicted value iE is a value obtained by predicting the calibrated value iC of the valve opening position current value, and is close to the calibrated value iC, the actual time taken to increase the scan from the start of the scan to the calibrated value iC during calibration becomes a value close to the fixed time T.

[0049] As a result, regardless of the type and individual differences of the electric actuator, the valve's opening characteristics, circuit construction, or the aging and degradation of the electric actuator or valve, the time spent scanning the current value applied to the electric actuator during calibration can be set to a roughly fixed time (an approximation of a fixed time T). Furthermore, even in work machines with multiple valves and electric actuators for actuating the valves, such as hydraulic excavators, the difference in scan time required to calibrate the valve opening position current value for each valve can be minimized, enabling standardization of the calibration process and contributing to improved work efficiency and calibration accuracy.

[0050] In this valve calibration system, the prediction calculation device 24 (calibration prediction device) includes at least one of the following: calibration information of past valve open position current values, manufacturing information of the electric actuator or valve, information of the machine using the valve, and information of the location where the machine is operated. This information is used as the information required to predict the calibration value of the valve open position current value, thereby enabling the acquisition of a high-precision prediction value iE based on this information.

[0051] Furthermore, in this embodiment, information about the valve opening position current value is accumulated as big data in the server 20, and the prediction value calculation device 24 provided in the server 20 forms a configuration that predicts a calibration value for the valve opening position current value based on the trend analysis results of the big data. Therefore, a prediction value iE with high accuracy can be obtained reliably.

[0052] Of course, the present invention is not limited to the above embodiments, and the calibration system and construction method of the present invention can be used not only to calibrate control valves installed in the hydraulic circuit of a hydraulic excavator, but also to calibrate various types of valves used in various working machines. Furthermore, the valve to be calibrated and the electric actuator for actuating the valve are not limited to the valve and electric actuator separately installed as in the above embodiments, but rather the valve and electric actuator can be installed as a whole.

[0053] Furthermore, in this embodiment, communication between the server and the vehicle controller is adapted to be performed via an external controller, such as a personal computer, and the calibration work is initiated based on the operation of the external controller. However, this is not a limitation. For example, if a monitoring device equipped with an operating mechanism is located in the cab of the machine, it can be configured to initiate and perform the calibration work by selecting the valve to be calibrated using the operating mechanism of the monitoring device. It can also be configured to automatically perform the calibration work, for example, at each predetermined operating time of the machine. Furthermore, by installing a communication device on the machine, it can also be configured to perform the calibration work by communicating with the server without going through an external controller.

[0054] Furthermore, in this embodiment, the predicted value iE, predicted by the calibration value prediction device installed in the server, is read into the vehicle controller 8, and the scan start current value setting device (scan start current value setting unit 15) installed in the controller 8 is configured to set the scan start current value iS. However, the scan start current value setting device for calculating and setting the scan start current value iS based on the predicted value iE can be installed on the server side, and the controller 8 can read the scan start current value iS set by the scan start current value setting device on the server.

[0055] Industrial applicability

[0056] This invention can be used for the calibration of valves configured to operate according to the current applied to an electric actuator.

Claims

1. A valve calibration system in a hydraulic circuit of a machine tool, the hydraulic circuit including a valve configured to operate to open and close a flow passage based on a current applied to an electric actuator, the valve calibration system being configured to calibrate a valve open position current value applied to the electric actuator when the valve opens the flow passage, the valve calibration system comprising: A calibration value prediction device is used to predict a calibration value of the valve opening position current value based on information about the valve opening position current value; A device for setting the scanning start current value; A hydraulic supply device for supplying hydraulic pressure at a fixed level to the inlet side of the valve; An applied current control device is used to initiate the application of current to the electric actuator to increase the current to the scan start current value, and further increase the scan of the applied current value of the electric actuator from the scan start current value at a predetermined rate; as well as A pressure measuring device for measuring pressure changes on the inlet or outlet side of the valve during the application of the current to the electric actuator. It is configured to obtain the calibration value of the valve opening position current value based on the current value applied when the pressure change is measured by the pressure measuring device, and The scan start current setting device sets the scan start current value according to the predicted calibration value, such that the time taken to increase the scan from the scan start to the predicted value predicted by the calibration value prediction device becomes a preset fixed time.

2. The valve calibration system of claim 1, wherein the calibration value prediction device includes at least one of the following: calibration information of past valve open position current values, manufacturing information of the electric actuator and valve, information of the machine using the valve, and information of the location where the machine can operate, as the information about the valve open position current value required to predict the calibration value of the valve open position current value.

3. The valve calibration system according to claim 1 or 2, wherein the information regarding the valve open position current value is accumulated as big data in a server, and the calibration value prediction device provided in the server predicts the calibration value of the valve open position current value based on the result of trend analysis of the big data.

4. A valve calibration method in a hydraulic circuit of a machine, the hydraulic circuit including a valve configured to operate to open and close a flow passage according to a current applied to an electric actuator, the valve calibration method being used to calibrate a valve open position current value applied to the electric actuator when the valve opens the flow passage, the valve calibration method comprising the following steps: Predict a calibration value for the valve opening position current value based on information about the valve opening position current value; Set the scan start current value; A fixed hydraulic pressure is supplied to the inlet side of the valve; The current applied to the electric actuator is initiated to increase the current to the scan initiation current value, and the scan of the current applied to the electric actuator is further increased from the scan initiation current value at a predetermined rate. The pressure change on the inlet or outlet side of the valve is measured during the application of the current to the electric actuator; as well as The calibration value for the valve open position current value is obtained based on the current value applied during the measured pressure change. The scan start current value is set according to the predicted calibration value, such that the time taken to increase the scan from the scan start to the predicted value of the calibration value of the current value at the predicted valve opening position becomes a preset fixed time.

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