CONDITION MONITORING SYSTEM

Description

[0001] The invention relates to a system for monitoring the condition of diaphragm valves and their pneumatic device.

[0002] Diaphragm valves can be used to meter various fluids, such as gases, vapors, or liquids. Diaphragm valves can be used, for example, to meter or distribute highly viscous or highly adhesive media. Diaphragm valves effectively prevent deposits and thus contamination. Valves based on the diaphragm principle are the metering valves with the lowest dead space. In addition to their very low dead space, diaphragm valves are also designed for optimized drainage, allowing residue-free removal of the medium.

[0003] This is particularly important for pharmaceutical plants and manufacturing processes, as they are subject to the high standards of strict validation aimed at ensuring consistent and reproducible quality. These requirements result in the need to be able to run various processes within a plant. In addition to the actual production process, these typically include cleaning, disinfection, and sterilization of the plant. Diaphragm valves have established themselves as the preferred valve in sterile process technology due to their advantageous design features.

[0004] The membranes used form movable, sealing walls that separate two spaces with usually different media (gases, liquids) and often also different pressure conditions.

[0005] An important quality characteristic of a diaphragm is its mobility, i.e., its ability to perform a stroke perpendicular to the clamping surface (diaphragm surface), which can be mechanically driven. Furthermore, the durability of the diaphragm is important, especially when handling aggressive media.

[0006] The mobility and durability of a membrane depend essentially on the material it is made of. Elastomers are primarily used as the base material for membranes, which can be reinforced with fabric inserts to achieve greater strength. Membranes made of ethylene propylene diene rubber (EPDM) have proven to be effective elastomers. Ethylene propylene diene rubber (EPDM) is a terpolymer elastomer (rubber) and thus a synthetic rubber. The material is characterized by high elasticity and good chemical resistance.

[0007] The diaphragm valves mentioned are often driven by corresponding pneumatic actuators. In these, an actuator is moved by supplying or removing a pressurized medium, particularly compressed air or control air. The compressed air supply to such a pneumatic device is provided via so-called control air connections.

[0008] Compressed air is a simple energy source in process engineering that can be used in a variety of ways in mechanical control systems. The quality of the compressed air is just as important a factor as the tightness of a system.

[0009] Preferably, the system includes a sensor for determining the quality of the control air. The control air can be monitored, for example, for the presence of other gases, particularly to assess the risk of explosion.

[0010] Pneumatic systems are often used in potentially explosive atmospheres. It is therefore important that no harmful or hazardous substances escape in the event of leaks. The use of compressed air often leads to careless handling of leaks, which in turn can lead to significant energy consumption in systems. Condition monitoring should therefore be holistic and monitor both the diaphragm valve and its actuator.

[0011] The basis for condition monitoring is the collection of various condition data acquired by sensors on the diaphragm valve and / or pneumatic device. This data must then be forwarded to a higher-level monitoring system. The monitoring system can analyze the condition based on intelligent algorithms.

[0012] EP 2 984 533 B1 describes the use of sensors on a diaphragm valve to determine the operating state and a method for evaluating this information. This allows a statement to be made regarding the actuating state. This is a first step toward condition monitoring. However, such a system cannot yet provide information about the fault-free and leak-free condition of a diaphragm valve, including its pneumatic system.

[0013] DE 10 2014 205 117 A1 describes the integration of an electronic circuit into the membrane. This is preferably an antenna formed by conductive particles on an elastomer layer. This allows operating and switching states to be determined, but the service life may be shortened due to the altered membrane characteristics. This system also only provides initial information regarding holistic condition monitoring.

[0014] Patent application DE 10 2015 210 208 A1 describes a method for determining a state variable of a valve diaphragm of an electronically controlled and motor-driven diaphragm valve and diaphragm valve system. This state variable is the diaphragm thickness, which can provide information about the wear condition of the diaphragm. This is to be determined by measuring a change in the diaphragm thickness due to a change in the position of the piston rod at a constant drive force controlled by force control. Furthermore, an analysis of the closing speed is to be used to identify the diaphragm condition. A condition monitoring unit for pneumatically driven diaphragm valves is not described. Furthermore, the system is not easily retrofittable, as the entire drive unit would have to be replaced, and it does not offer comprehensive condition monitoring.

[0015] DE 10 2015 210 210 A1 describes a method for diagnosing a diaphragm valve, as well as a diagnostic system for a diaphragm valve. The system first determines a parameter for the diaphragm, the valve, and the valve's operation. From these parameters, it uses an algorithm to determine a state parameter for wear (remaining service life). The input parameters can be static data stored locally or in the cloud. However, at least one parameter is provided by a sensor positioned on the valve. The system can only be implemented through a complex retrofit to already installed diaphragm valves and provides condition predictions exclusively for the diaphragm, not for the diaphragm valve and its pneumatic system.

[0016] DE 10 2015 219 273 A1 describes a diaphragm device with a rigidly designed diaphragm housing through which a working channel extends between an inlet and an outlet. A flexible diaphragm is accommodated in the working channel, which is sealingly connected to the diaphragm housing and, together with the diaphragm housing, defines a variable-sized working space. It is provided that a control means is assigned to the diaphragm housing, which is designed to initiate a diaphragm movement onto the diaphragm in order to enable a cross-sectional change of the working channel, which is at least partially defined by the diaphragm.

[0017] EP 3 263 963 A1 discloses a fluid control valve comprising a valve main body and a vibration sensor. The valve main body has an actuating portion and a valve portion. The sensor detects the vibration generated in the valve main body. The fluid control valve further comprises a controller for executing an abnormality determination program and determining the valve main body as normal when the sensor detects vibration with an amplitude exceeding the predetermined threshold, while determining the valve main body as abnormal when the sensor does not detect vibration with an amplitude exceeding the predetermined threshold.

[0018] WO 2020 / 012828 A1 describes a fluid control device capable of acquiring data related to the internal processes of the device. A fluid control device includes a hood portion to which sensors for sensing processes within the fluid control device are mounted. The valve body is provided with a recessed portion for fitting into the hood portion and a slot that allows a communication cable connected to the sensors to be led out to the outside. One end of the communication cable is open on the side opposite a base portion in which a flow channel is formed, and the cable passes from the outside to the recessed portion side.

[0019] EP 1 726 855 A2 discloses a feed valve with an integrated leak sensor for use in conjunction with automatic feeding systems in the agricultural sector. The novel feature is that the valve includes a sensor unit for detecting a leak in the valve's membrane.

[0020] US 2005 / 009079 A1 describes detecting the diaphragm position and movement of diaphragm valves using one or more sensors arranged directly on the diaphragm or detecting the diaphragm itself rather than an associated part of a valve. The disclosure provides for many different types of sensors and also temperature compensation.

[0021] EP 0 637 713 A1 discloses a diagnostic system for control and shut-off valves and uses the processor of an intelligent position controller as a digital signal processor, which is connected to sensors monitoring the operation of the valve or measuring operating variables of the valve and issues an alarm signal if the measured values ​​deviate from comparison measured values ​​previously recorded during proper operation of the valve.

[0022] WO 2015 / 020986 A1 discloses a process control device. The process control device comprises a process control valve, an actuator, a digital valve controller, and a processor. The actuator is connected to the process control valve and configured to control a position of the process control valve.

[0023] The object of the invention is to provide a system for monitoring the condition of a diaphragm valve, which reliably determines at least one state variable of a diaphragm valve and its pneumatic device. The determination should be possible during regular operation. The system should provide information about the condition of the diaphragm valve and the pneumatic device and also be able to indicate any need for action. The system should be easy to retrofit to existing diaphragm valves and their pneumatic device, in particular without disassembly, and without having to interrupt ongoing operation. The system should be able to be operated without wiring and without generating any additional maintenance work. The diaphragm and its operation should not be adversely affected. The system should run as problem-free and uninterrupted as possible and should be able to be manufactured as inexpensively and as easily as possible.

[0024] This object is achieved according to the invention by a condition monitoring system according to the claims. Preferred variants can be found in the dependent claims, the description, and the drawings.

[0025] According to the invention, a system for condition monitoring of diaphragm valves and their pneumatic device, wherein the system can be connected to the pneumatic device with an interface and to the control air with a further interface, wherein the condition monitoring system has two pneumatic connections, a supply connection and a consumer connection, and wherein the condition monitoring system has an external thread on the consumer connection that can be screwed directly into a pneumatic drive, is designed to carry out at least two of the following steps: determining an operating pressure, determining a control pressure, determining forces acting in a drive axis of the valve, determining a vibration signal, determining an acoustic signal, analyzing the signals with the aid of a neural network and wherein the system is designed to determine a pressure; preferably the control pressure;to record as a function of time in order to analyze the switching process and the switching position of the valve.;

[0026] According to the invention, a system for monitoring the condition of a diaphragm valve and its pneumatic system is connected to the control air connection of the pneumatic system of a diaphragm valve. This allows the pneumatic drive, in particular at least one variable, of a diaphragm valve to be monitored. The monitoring by at least one sensor relates to the operating pressure, the control pressure, the forces acting on the valve, the noise, and the vibrations. This enables functional monitoring, condition-based maintenance, and energy consumption monitoring for pneumatically driven diaphragm valves. An integral component of the invention is wireless communication using the means for data exchange in the sense of the Internet of Things, specifically the Industrial Internet of Things, which enables simple, widespread installation.

[0027] In an advantageous embodiment of the invention, the process and state variables are recorded by at least one sensor. Sensors for detecting vibrations, sound, and especially pressure and / or force, which are used to deform the membrane, are advantageously suitable as sensors. These represent the essential process and state variables in a pneumatic system, from which conclusions can be drawn about the system's state. The aforementioned measured values ​​can be recorded by one sensor for each measured value or by a common sensor.

[0028] In one variant of the invention, the temporal profile of the control pressure and / or the sound and / or vibration signal is determined to monitor the switching process and the position of the diaphragm valve. In a particularly advantageous variant, the temporal profiles of these signals are used in a fused evaluation to determine the open and closed states as well as the steady-state open and closed states, and to detect and indicate deviations from safe and error-free states. This makes it possible, for example, to dispense with a position indicator on the valve.

[0029] For analysis, the temporal progression of the signals is analyzed in a neural network according to the invention. For this purpose, the neural network is constructed from six input dimensions and six neurons in the intermediate layer, so-called hidden neurons. This neural network was trained with countless test data and can extremely reliably distinguish between safe and unsafe states of the diaphragm valve based on meaningful features, such as significant Fourier coefficients. Furthermore, the compressed air flow rate, for example, can be approximated from the temporal sound progressions. This information can, in turn, be used for the computer-based detection of compressed air leaks. In a particularly advantageous variant of the invention, this state information can be further validated via a flow turbine, which serves as the autonomous power supply of the system for monitoring the condition of diaphragm valves.

[0030] Advantageously, the analysis of temporal signal profiles (pressure, force, sound, vibration, acceleration, etc.) is based on absolute differences, local maxima, time differences, and the magnitudes of signal changes. Periodically changing signals are also used for analysis. Remarkably, the vibration signals are used as a function of acceleration over time and / or as a function of frequency over time to analyze the switching process as well as the valve position.

[0031] In a particularly advantageous variant of the invention, the analysis of the pressure signal over time in combination with the acoustic signal over time serves to determine the valve's switching time. If this time is within a certain time range, a safe valve state can be indicated. If the switching time is outside this range, an unsafe valve state can be indicated.

[0032] According to the invention, the wear status of a diaphragm can be determined based on the temporal progression of the drive variable pressure and / or the force-strain curve, but also the rate of change and the sign of the rate of change as well as the time difference between changes in the sign of the rate of change and the maximum of the drive variable. In a further embodiment of the method, anomalies with respect to a stored behavior are recorded in the evaluation unit and / or in the neural network. States or operating profiles of at least one drive variable, in particular pressure and / or force, of the diaphragm are stored in the evaluation unit, or the neural network is trained with expected profiles. This enables concrete feedback regarding the wear status and can be used to indicate a necessary diaphragm replacement.

[0033] In one variant of the invention, the diaphragm force is modeled based on a force equilibrium by determining the pressure increase during the switching process of the diaphragm valve. Advantageously, separate force measurement could be omitted. The diaphragm condition can be analyzed based on the change in the modeled force curve. The setting process due to the plastic deformation of the diaphragm in the valve seat can be reproduced using the modeling, and if the pressure falls below a defined limit, a maintenance recommendation can be displayed.

[0034] According to the invention, the valve actuator type is determined based on the combined evaluation of the sound, vibration, and pressure signals. This is particularly advantageous for the automatic initialization of the system for condition monitoring of diaphragm valves, as the type determination occurs automatically through an initial switching operation, entirely without the intervention of the assembly personnel.

[0035] In one variant of the invention, an element for connecting external sensors is integrated. This would allow a temperature sensor to be connected to the valve to determine the media temperature. In addition to the number of switching cycles, the media temperature is a crucial parameter for predicting the remaining service life of the diaphragm. Using the neural network, model-based and condition-oriented maintenance recommendations are thus possible, in addition to condition monitoring.

[0036] The media temperature can be calculated from the drive temperature and the ambient temperature.

[0037] By calculating the temperature of sealing elements, a lifetime prediction is possible.

[0038] Advantageously, the fusion of the sound and vibration signals can provide an indication of the location in the event of an unsafe operating condition or even a malfunction. While the vibration sensor records vibrations in the immediate vicinity of the condition monitoring system, the acoustic sensor also detects more distant noises. After a certain learning period, the neural network can very precisely distinguish between known, typical, and unexpected acoustic signals in the environment. By comparing the signals with the vibration signal, the condition of the monitored diaphragm valve and its pneumatic system can be safely ruled out. The location of the signal anomaly can be indicated using the integrated position sensor in the condition monitoring system.

[0039] In a further embodiment of the invention, the data transmission means is a radio communication means, in particular a near-field radio means. Wireless communication is an integral component of the system for operating a pneumatic device. This system features both near-field communication via RFID, Bluetooth LE, Thread, Zigbee, or similar, as well as far-field communication via Wi-Fi, LPWAN, or mobile communications standards such as GSM, LTE, or similar. To ensure the security of data transmission and increase its data transmission rate, several technologies can also be combined.

[0040] Advantageously, the power supply for the data acquisition and communication system is wireless, for example, via a supply battery. However, it is also conceivable for the data acquisition unit to draw the required energy from the radio interface. In a particularly advantageous variant of the invention, the system can be self-powered to operate a pneumatic device through "energy harvesting." A particularly suitable option is to generate energy from the compressed air flowing through the valve when it is switched. This air drives a turbine integrated into the monitoring system and, together with a generator, provides the power supply for the electronics. A built-in battery or accumulator serves to bridge long periods without energy generation. At the same time, in this variant, the turbine's speed can be used as a flow sensor.

[0041] According to the invention, the integrated sensor element is used for position determination, providing precise position information via wireless data transmission in the event of maintenance. Especially in complex systems in the process industry, the time-consuming and therefore costly location of the affected valve diaphragm and its pneumatic system is simplified.

[0042] In one variant of the invention, an element for connecting external sensors is integrated. For example, process-relevant variables as well as state variables of the pneumatic system can be recorded via external sensors and transmitted to a higher-level analysis or process control system via the system's wireless data transmission for operating a pneumatic device.

[0043] The system's integrated acoustic and / or visual information output is advantageous. This signal indicates, for example, the system's functionality. It can also indicate maintenance requirements.

[0044] According to the invention, the element integrated into the system can be used for information input during the initialization process. Furthermore, manual actuation of the diaphragm valve is possible. Furthermore, the configuration of a maintenance process is possible.

[0045] In a simple embodiment of the invention, it is conceivable that the data and / or power supply is cable-based.

[0046] Wireless data transmission and wireless power supply enable simple, widespread installation in industrial plants. One advantage of this invention is the simple, even retrofitting of the system for condition monitoring of diaphragm valves and their pneumatic devices at the actuator's control air connection, which can be easily accomplished using standardized connection threads. The condition monitoring system has two pneumatic connections: a supply connection and a consumer connection; there can also be multiple consumer connections. In one version, the condition monitoring system has an external thread at the consumer connection that can be screwed directly into a pneumatic actuator.

[0047] In one embodiment of the method, the acquired data is evaluated in an evaluation unit, and the evaluation results are transmitted to a central control unit via the data transmission means. This has the advantage of reducing the amount of data to be transmitted.

[0048] A combination of pressure and sound signals for evaluating the valve position ensures reliable end position feedback, which would otherwise only be possible with a separate position sensor or two end position sensors.

[0049] Further features and advantages of the invention will become apparent from the description of embodiments with reference to drawings and from the drawings themselves.

[0050] It shows: Figure 1a system for condition monitoring of a diaphragm valve and its pneumatic device, Figure 2a diaphragm valve with a pneumatic device and installed condition monitoring system.

[0051] Figure 1 shows a system for monitoring the condition of a diaphragm valve 1 for determining process and / or state variables, which is connected to the pneumatic device via an interface 2. Pressure, force, position, sound, vibrations, oscillations, flow, temperature, and humidity can be determined as process or state variables. The system for monitoring the condition of a diaphragm valve and its pneumatic device 1 is equipped with one or more corresponding data acquisition devices for this purpose. Furthermore, the system for monitoring the condition of a diaphragm valve 1 is equipped with a further interface 3 to which the control air can be connected. A wired or wireless transmission of the measurement data to a further processing unit can take place via an interface (not shown).

[0052] A display can range from a simple digital ON / OFF display to comprehensive measured value information, including time series. However, more important for this condition monitoring system 1 is the transmission of data to a higher-level data processing unit. For this purpose, the data may be processed through filters and then forwarded.

[0053] The Figure 2 shows a diaphragm valve 4 with connections 7, wherein an inlet and an outlet are provided. The diaphragm valve has a diaphragm 5, which is moved in the direction of the drive axis by means of a pneumatic device 6. A system for monitoring the condition of a diaphragm valve and its pneumatic device 1 is provided on the pneumatic device 6 according to the invention.

Claims

1. System for condition monitoring of diaphragm valves (1) and the pneumatic device thereof, wherein the system can be connected by an interface (2) to the pneumatic device and can be connected by a further interface (3) to the control air, wherein the system for condition monitoring has two pneumatic connections, a supply connection and a consumer connection, and wherein the system for condition monitoring has at the consumer connection an external thread that can be screwed directly into a pneumatic drive, and wherein the system is configured to carry out at least two of the following steps: - determination of an operating pressure, - determination of a control pressure, - determination of acting forces in a drive shaft of the valve, - determination of a vibration signal, - determination of an acoustic signal, - analysis of the signals by means of a neural network, and wherein the system is configured to detect a pressure, preferably the control pressure, in dependence on time in order to analyse the switching operation and the switching position of the valve.

2. System according to Claim 1, characterized in that the system is configured, for analysing the pressure signals, to determine as characteristic values pressure differences, local maxima, time differences and / or magnitudes of the pressure change.

3. System according to Claim 1 or 2, characterized in that the system is configured to detect forces acting in the valve in dependence on time in order to analyse the switching operation and / or the position of the valve.

4. System according to one of Claims 1 to 3, characterized in that the system is configured to detect periodically changing quantities in order to analyse the switching operation and the position of the valve.

5. System according to one of Claims 1 to 4, characterized in that the system is configured to evaluate vibration signals as a function of acceleration over time and / or frequency over time in order to analyse the switching operation of the valve.

6. System according to one of Claims 1 to 5, characterized in that the system is configured to determine flow conditions in the valve from acoustic signals.

7. System according to one of Claims 1 to 6, characterized in that the system is configured to use acoustic signals for compressed air leakage detection.

8. System according to one of Claims 1 to 7, characterized in that the system comprises a neural network for analysing the signals, wherein the neural network preferably has at least 4 input dimensions and at least 4 neurons in an intermediate layer.

9. System according to one of Claims 1 to 8, characterized in that the system is configured to determine the switching time of the valve by a combination of a pressure signal analysis with an acoustic signal analysis or a pressure signal analysis with a vibration signal analysis.

10. System according to one of Claims 1 to 9, characterized in that the system is configured to identify the drive type of the valve by a combination of a pressure signal analysis with an acoustic signal analysis or a pressure signal analysis with a vibration signal analysis.

11. System according to one of Claims 1 to 10, characterized in that the system is configured to use acoustic signals to detect faults.