KR20100071443A - A system for monitoring abnormalness of a valve by detecting operation current of a valve used for controlling oil pressure - Google Patents

Abstract

PURPOSE: A system for detecting the breakdown of a valve by detecting the operating current of the valve used for an oil pressure control is provided to accurately detect the actual operating current flowing in the valve used for an oil pressure control. CONSTITUTION: A system for detecting the breakdown of a valve comprises a power source(10), a current detector(11), a current amplifier(12), an operation unit(13) and an output unit(14). The power source supplies power. The current detector is connected to the valve used for an oil pressure control. The current detector detects the operating current flowing in the valve. The current amplifier amplifies an operating current signal. Using the operating current signal, the operation unit detects the breakdown and determines the reason for the breakdown. The output unit processes and outputs the information on the breakdown detection and the reason for the breakdown.

Description

A valve failure detection system that detects valve failure by detecting the operating current of a valve used for hydraulic control {A SYSTEM FOR MONITORING ABNORMALNESS OF A VALVE BY DETECTING OPERATION CURRENT OF A VALVE USED FOR CONTROLLING OIL PRESSURE}

This document relates to a valve failure detection system, and more particularly to a valve failure detection system that detects a valve failure by using the operating current of the valve used for the hydraulic control.

In general, the hydraulic control system used for field automation is divided into a servo valve, a proportional control valve, and a solenoid valve for directional control. There are many types and structures of servo valves, the most common of which is a flow control servo valve by an electrohydraulic servo mechanism. It controls the flow of high pressure oil up to several hundred kilograms per square centimeter by inducing the pressure of the hydraulic oil into a weak electrical input of several kW, converting it into mechanical displacement and converting the displacement back into hydraulic change.

At this time, it is difficult to measure the flow of several mA current of the servovalve. This is because the change in impedance for measurement causes not only the valve characteristics but also the most important servo valve center point to one side. Therefore, in the past, since the actual current detection device of the valve coil was not used between the control device and the valve, and the valve was disconnected and predicted for failure, the failure occurred again in a situation where it was difficult to identify and analyze the cause of the failure and abnormality. There are many examples.

In the background art described above, a valve which detects the actual operating current of the servovalve so that the center point of the valve does not move and does not deteriorate the characteristic of the valve, and detects the failure of the valve by using the operating current of the servovalve. The problem is to provide a fault detection system.

Valve failure detection system as one means for solving the above problems is a power supply for supplying power, a current detector connected to the valve used for flow control to detect the operating current flowing through the valve, the current to amplify the operating current signal The amplifier includes an operation unit for detecting a failure by using the operating current signal and determining a cause of the failure, and an output unit for outputting the failure detection and the information on the cause of the failure after signal processing.

The current detector detects an operating current flowing through the valve coil by connecting a non-inductive resistor in parallel to an electrical signal output terminal of the valve and detecting a voltage drop of the resistor.

The current detector may further include an isolation amplifier so as not to affect the valve circuit electrically. The current detector may detect the operating current in an output form of 4-20 mA or 0-10 V.

The current detector outputs the operating current as a quantitative analog quantity when the valve is a servo valve or a proportional control valve, or as an error signal that is determined based on a set value, and operates when the valve is a solenoid valve. Can be output as on / off signal.

The operation unit may fail using a result of comparing one or more of the operation current signal and the operation on / off signal of the solenoid valve, the operation control signal for the valve, the hydraulic oil pressure signal, the valve spool feedback signal, and the cylinder position value. Can be detected and the cause of the failure can be determined.

The pressure transmitter may further include a pressure transmitter connected to a hydraulic line to measure the pressure of the hydraulic line, converting the hydraulic pressure into an electrical signal, generating the hydraulic oil pressure signal, and transmitting the hydraulic oil pressure signal to the operation unit.

The apparatus may further include at least one of a display unit for displaying the failure detection and the cause of the failure on the screen, and a communication unit for transmitting the failure detection and the failure cause information through a wired or wireless communication method.

According to the present invention there is an effect that can be used to accurately detect the actual operating current flowing through the valve used for the hydraulic control using the valve failure detection device and to use the valve failure detection.

In addition, there is an effect that can be installed irrespective of the classification of the servo valve, the proportional control valve, the directional solenoid valve.

In addition, if the disconnection and control abnormality of the valve occurs through the combination and operation function of the valve operation control signal and the cylinder position signal, it is possible to analyze the failure factor through quantitative signal analysis, and to match the factors of the function degradation. Cause tracking is effective.

In addition, by managing the history of the signal, it is possible to analyze the operator at any time, it is possible to predict the failure state according to the level change of the signal, there is an effect that can be pre-maintenance work.

Hereinafter, embodiments of the present disclosure will be described with reference to a valve failure detecting system for detecting a real operating current of a valve used for hydraulic control and detecting a failure of the valve using the operating current of the valve.

1 is a schematic block diagram of a valve failure detection system according to an embodiment of the present invention, Figure 2 is a view showing a state in which the current detection unit of the valve failure detection system according to an embodiment of the present invention is connected to the valve. .

According to the present embodiment, a real operating current supplied to a coil, such as a servo valve or a proportional control valve, which can adjust the flow rate according to the strength of the current, is detected and converted into an analog signal, and the valve is broken. The ability to compare, compute, analyze and judge existing signals for use in sensing systems is added.

Referring to FIG. 1, a valve failure detection system according to the present embodiment includes a power supply unit 10 for supplying power, a current detection unit 11 connected to a valve coil used for flow control to detect an operating current flowing through the valve, and detection. A current amplifying unit 12 for amplifying the operated operating signal, a calculating unit 13 for detecting a failure using the detected operating current signal, and determining the cause of the failure, and outputting the failure detection and the information on the failure cause after signal processing And an output unit 14.

The present embodiment relates to a valve used for hydraulic control, for example, a servo valve control. According to the present embodiment, as illustrated in FIG. 2, a servo current of the valve current detection unit 11 is used for hydraulic control in a hydraulic control system. The electrical signal output terminal of the valve 20 can be connected in series connection structure. Then, the current detection unit 11 detects the actual operating current supplied to the main circuit line of the servovalve installed in the field, and the calculation unit 13 detects the failure using the amount of current and determines the cause of the failure. At this time, since the magnitude of the current detected by the current detector 11 is very small, the signal strength is increased through the current amplifier 12.

According to this embodiment, the servo valve and the proportional control valve can detect the actual amount of current flowing through the coil of the valve by applying a detection device capable of directly detecting the valve operating current to the hydraulic control circuit for controlling the cylinder. In this case, the actual operating current flowing through the coil of the valve detected by the current detector 11 may be output as a quantitative analog amount or as an error signal determined based on the set value. In addition, the solenoid valve may be output as an on / off signal to know the actual operating state.

3 is a schematic circuit diagram of a valve failure detection system according to an embodiment of the present invention.

In the valve failure detection system according to the present embodiment, the power supply unit 10 for supplying power transforms a power supply voltage of 110 V to 220 V to an extent that can be used in the valve failure detection system, for example, 5 V, +15 V, and -15 V. It is transformed into voltage to supply power to each function module.

In addition, the current detection unit 11 according to the present embodiment is connected to, for example, an electrical signal output terminal of the servovalve coil to detect an operating current flowing through the servovalve. For example, at least one non-inductive resistor 30 may be connected to both ends of the electric signal output of the servo valve in parallel, and a voltage drop of the resistor may be detected to detect an operating current flowing through the valve coil. Here, non-inductive resistance means that the magnitude of the resistance is relatively small compared to the resistance of the valve system so that the connection does not affect the valve system. In this case, the current detector 11 may detect the operating current in an output form of 4-20 mA or 0-10 V. In addition, the current detector 11 according to the present embodiment may further include an isolation amplifier 31 so as not to affect the valve circuit electrically.

In this way, the resistance for current detection is used as the non-inductive resistor 30 and additionally, the isolation amplifier 31 is connected to minimize the impedance change of the valve circuit so that the current detector according to the present embodiment can be connected to the valve circuit. Minimize the impact on the electrical signal control and mitigate the bias of the valve center point to one side.

For example, as shown in FIG. 3, the current detector 11 according to the present embodiment connects two 0.1Ω resistors 30 in parallel to each output terminal of the servovalve with non-inductive resistance. The effect of connecting resistors is measured, and the voltage drop across these resistors can be measured to detect the actual operating current flowing through the servovalve. In addition, according to the present exemplary embodiment, a plurality of valves, for example, four channels of valves, may be simultaneously detected in one valve failure detection system. In this case, a current detector for detecting valve operating current of each channel may be the same as described above. It can be implemented in a way.

In addition, the current amplifier 12 according to the present exemplary embodiment includes a forward-current amplifier 12a and a reverse-current amplifier 12b as shown in FIG. Operate to amplify. Then, the calculation unit 13 according to the present embodiment detects a failure by using the detected operating current signal of the valve and determines the cause of the failure.

In addition, according to the present embodiment, a failure detection and an output unit 14 for outputting the information on the cause of the failure after signal processing are included. The apparatus may further include a display unit 35 for displaying a failure detection and the cause of the failure on the screen, and a communication unit 36 for transmitting the failure detection and the failure cause information through a wired or wireless communication method. As the communication unit 36 is provided, for example, the detection value is transmitted to the external client PC as an analog amount, and the detection result can be confirmed in real time through online processing, and the change can be detected at any time by detecting the change. In addition to detecting a valve failure in the on-line state, disconnection of the main circuit line, as well as an abnormality determination and failure detection of the hydraulic control device may be performed by comparing the control target value and the deviation of the real current.

4 shows a schematic circuit diagram of a hydraulic control system according to an embodiment of the present invention.

Referring to FIG. 4, the hydraulic control system according to the present embodiment includes a servo valve 41, a plurality of solenoid valves 42, 43, 44, and 45, a cylinder 46 in which opening and closing is controlled by a plurality of valve operations, and operating oil. The pressure signal includes a pressure transmitter 47 and an operation unit 48 connected to the hydraulic line to measure the pressure of the hydraulic line and converting the pressure signal into an electrical signal. Here, the plurality of solenoid valves 42, 43, 44, 45 are respectively controlled to close the valve in an emergency situation, such as a general valve 42, a manual valve 43 controlled by a manual operation by the user, overflow of the hot water, etc. The emulsion valve 44 may be used as a pressure relief valve 45 that operates to equalize the pressure between cylinders for initial setting.

In order to operate the valve failure detection system described above, the current detection units 40a and 40b according to the present embodiment are mounted on the respective valves, and the actual operating current flowing through the valve is detected and transmitted to the operation unit 48.

The calculation unit 48 according to the present embodiment not only detects the operation current signal of the valve, but also the operation on / off signal of the solenoid valve, the operation control signal for the servo valve 41, the operating oil pressure signal, the valve spool feedback ( The result of comparing one or more of the valve spool feedback signal and the cylinder position value can be used to detect the failure and determine the cause of the failure. Here, the valve spool feedback signal represents the opening amount of the spool for adjusting the flow rate in the valve.

As shown in FIG. 4, the operating current signal of the valve connected to the output terminal of the servo valve detected according to the present embodiment may be provided as a current input of 4-20 mA intensity, and the operation on / off signal of the solenoid valve may be It can be provided in the detection unit connected to the solenoid valve, the hydraulic oil pressure value can be provided as a current input of 4 to 20 mA strength in the pressure transmitter 47, the cylinder position value is a current of 4 to 20 mA strength in the cylinder 46 Can be provided as an input.

According to the present embodiment, it is possible to measure the actual operating current of the servovalve 41 so that a system capable of diagnosing and predicting a general failure of the hydraulic control device using the servovalve can be constructed. As the actual operating current of the servovalve becomes measurable, in addition to the actual operating current information of the servovalve, the set value, the cylinder position value, the hydraulic pressure, the valve spool feedback value, etc. are further considered, that is, these values are calculated and compared. Therefore, it is possible to clearly diagnose failure factors such as cylinder, servovalve, and hydraulic oil contamination.

5 is a graph showing the operating characteristics of the servo valve before and after the connection of the valve failure detection apparatus according to an embodiment of the present invention.

The valve fault detection device connected to detect the valve current according to the present embodiment uses an inductive low resistance to minimize the impedance change due to the device connection and to have an insulation function at the current detection stage, for example, an isolation amplifier. Can be used to detect valve current without affecting existing installations.

Figure 5 (a) shows the valve operation before connecting the valve failure detection device according to the present embodiment, (b) shows the valve operation after connecting the valve failure detection device, both of which change the operating current The change in flow rate is shown. Comparing this, it can be seen that the flow rate change according to the change of the operating current of the hydraulic valve before and after installation, that is, the slope of the graph is measured equally, so that the valve operating characteristics before and after the connection of the valve failure detecting device according to the present embodiment are the same. .

Although described above with reference to the drawings and embodiments, those skilled in the art that the present invention can be variously modified and changed within the scope without departing from the spirit of the invention described in the claims below I can understand.

1 is a schematic block diagram of a valve failure detection system according to an embodiment of the present invention.

2 is a view showing a state in which the current detection unit of the valve failure detection system according to an embodiment of the present invention is connected to the valve.

3 is a schematic circuit diagram of a valve failure detection system according to an embodiment of the present invention.

4 is a schematic circuit diagram of a hydraulic control system according to an embodiment of the present invention.

5 is a graph showing the operating characteristics of the servo valve before and after connecting the valve failure detection apparatus according to an embodiment of the present invention.

<Description of the code for the main configuration of the drawings>

10: power supply unit 11: current detection unit

12: current amplifier 13: arithmetic unit

14: output unit

Claims (8)

A power supply unit supplying power; A current detector connected to a valve used for hydraulic control to detect an operating current flowing through the valve; A current amplifier for amplifying the operating current signal; A calculation unit for detecting a failure by using the operating current signal and determining a cause of the failure; And Output unit for outputting the failure detection and the cause information of the failure after signal processing Including, valve failure detection system. The method according to claim 1, The current detection unit, the valve failure detection system, characterized in that for connecting the non-inductive resistance in parallel with the electrical signal output terminal of the valve and detects the voltage drop of the resistance to detect the operating current flowing through the valve coil. The method according to claim 1, The current detection unit, the valve failure detection system, characterized in that it further comprises an isolation amplifier so as not to affect the valve circuit. The method according to claim 1, The current detection unit, the valve failure detection system, characterized in that for detecting the operating current in the form of output of 4 ~ 20mA. The method according to claim 1, The current detector outputs the operating current as a quantitative analog quantity when the valve is a servo valve or a proportional control valve or as an error signal that is determined based on a set value, and operates when the valve is a solenoid valve. And a valve failure detection system characterized in that it is output as an on / off signal. The method according to claim 1, The operation unit may fail using a result of comparing one or more of the operation current signal and the operation on / off signal of the solenoid valve, the operation control signal for the valve, the hydraulic oil pressure signal, the valve spool feedback signal, and the cylinder position value. A valve failure detection system, characterized in that for detecting and determining the cause of the failure. The method according to claim 6, And a pressure transmitter connected to a hydraulic line to measure the pressure of the hydraulic line, converting the hydraulic pressure into an electrical signal, generating the hydraulic oil pressure signal, and transmitting the pressure signal to the operation unit. The method according to claim 1, And at least one of a display unit for displaying the failure detection and the cause of the failure on a screen, and a communication unit transmitting the failure detection and the failure cause information through a wired / wireless communication method.

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