Method for operating a fluid control device and fluid control device

Abstract

Method for operating a fluid control device in the form of a valve (14) or a mass flow controller (10) comprising a valve (14), with a fluid housing (16) in which a valve seat (20) is formed, a closing element (22) which interacts with the valve seat (20) to open or close a flow path through the fluid housing (16), and with at least two units from a group comprising an operating time counter (24), a flow meter (26), a counter (28) for recording a total actuation time of a valve plunger (30), a sensor (32) for recording a medium temperature, and a sensor (34) for recording a device temperature, wherein the measured values ​​recorded by the units are multiplied by a weighting factor and a correction factor individual to the respective measured value.wherein the individual weighted and corrected measured values ​​are added together to form an index value (I), and wherein a degree of wear of the valve (14) is determined based on the index value (I).

Description

[0001] The invention relates to a method for operating a fluid control device, i.e. a valve or a mass flow controller comprising a valve, as well as a fluid control device in the form of a valve or a mass flow controller.

[0002] The term "fluid control device" is used to refer to valves and mass flow controllers that include one or more valves. For ease of reading, the terms "valve" and / or "mass flow controller" are often used instead of "fluid control device" in the following text, as these are common terms for those skilled in the art.

[0003] Valves typically experience wear and tear over time, for example in the diaphragm or the valve actuator. This wear can manifest as thinning of the diaphragm material or abrasion in the valve actuator. Over time, this can lead to leakage or other malfunctions in the valve or in a mass flow controller that incorporates a valve.

[0004] Such wear and tear is partly exacerbated by the operating conditions of the valve or mass flow controller, such as temperature and flow rate. When dosing acids or other aggressive chemicals or gases, the valve material, particularly the diaphragm, can be attacked by the media used over an extended period.

[0005] In processes involving aggressive media such as ammonia gas, wear is minimized through regular maintenance by cleaning the lines with nitrogen.

[0006] However, since the wear parts are usually not accessible without disassembling the valve or mass flow controller, it is difficult to obtain information about the condition of the wear parts during operation and to reliably predict the remaining service life or to identify maintenance needs.

[0007] In processes involving neutral gases, regular calibration is advantageous to ensure optimal functioning of the fluid control device.

[0008] It is common practice to record various measurements in a valve or mass flow controller to draw conclusions about its condition or calibration needs. However, the individual measurements are only considered separately, which makes a meaningful interpretation of the measured values ​​difficult.

[0009] DE 195 24 237 C2 describes a flow control valve unit for fluids, comprising a flow control valve with an externally closed housing enclosing an interior space. The flow resistance of the valve can be adjusted by moving a movable and adjustable actuator. The flow control valve unit includes a monitoring device that can monitor the wear condition of the flow control valve in various ways.

[0010] DE 101 28 448 B4 discloses a method for diagnosing a process valve with a valve disc arranged in a valve body for controlling the free cross-section of a pipeline through which a process medium flows, depending on a process control signal. During operation, measured values ​​are recorded in the process valve and combined to form an instantaneous load value. The load values ​​are summed over the operating time and compared with empirical values. The probability of a process valve failure is determined from the comparison result.

[0011] DE 10 2016 205 454 A1 discloses a method for determining and / or predicting an operational condition of an inlet valve.

[0012] DE 201 20 609 U1 discloses a diagnostic device for a fluid power system for detecting at least one wear parameter that causes wear of the fluid power system, and for reporting at least one wear condition determined on the basis of the at least one wear parameter.

[0013] It is therefore an object of the present invention to provide a way to determine the condition of wear parts in a valve or a mass flow controller with a valve, i.e. in a fluid control device, taking into account various influencing parameters.

[0014] This problem is solved according to the invention by a method for operating a fluid control device, i.e. a valve or a mass flow controller comprising a valve, with a fluid housing in which a valve seat is formed, a closing element which cooperates with the valve seat to release or close a flow path through the fluid housing, and with at least two units from a group comprising an operating time counter, a flow meter, a counter for recording a total actuation time of a valve plunger, a sensor for recording a medium temperature and a sensor for recording a device temperature.The measured values ​​recorded by the units are multiplied by a weighting factor and a correction factor specific to each measured value, the individual weighted and corrected measured values ​​are added together to form an index value, and a degree of wear of the valve is determined based on the index value.

[0015] If a threshold value of the index value is exceeded, replacement of the valve or individual parts of the valve is required. Alternatively or additionally, calibration may be required.

[0016] The threshold is determined primarily based on empirical data.

[0017] The basic idea of ​​the invention is to combine various parameters with different physical units into a meaningful wear index. In this way, the condition of the valve or the mass flow controller comprising a valve can be determined without having to inspect the valve itself.

[0018] By determining an index value that incorporates various measured values, a user only needs to consider a single value, rather than an unstructured dataset as with previous solutions. The index value is particularly easy for a user to interpret.

[0019] Multiplying by the correction factor makes the measured values ​​recorded by the different units comparable and allows them to be compared to each other.

[0020] The weighting factor reflects the influence of a measured value on wear. This weighting further improves the reliability of determining wear based on the index value.

[0021] The weighting factor, for example, takes values ​​between zero and ten.

[0022] The correction factor can include an adjustment factor, where the adjustment factor for each measured value is determined by dividing a defined base value, identical for all units, by a limit value defined for the respective unit. The adjustment factor serves to standardize the numerical ranges of the physical quantities, thus making the individual values ​​easily comparable.

[0023] The defined base value is, for example, 100.

[0024] These limit values ​​include, for example, a maximum operating time, a maximum total flow rate, a maximum total settling time, a maximum device temperature, or a maximum media temperature.

[0025] Alternatively or additionally, the correction factor can include a linearization factor, which linearizes the progression of the individual measured values. Specifically, the linearization factor takes into account the mathematical influence of the value development, in particular whether the value development follows a linear or an exponential curve. Linearizing individual measured values ​​further improves the reliability of determining wear based on the index value.

[0026] Preferably, the correction factor is formed by multiplying the adjustment factor and the linearization factor together.

[0027] In the case of a linear progression of the measured value, as is the case, for example, with operating time, flow rate and total settling time, the linearization factor is 1.

[0028] The weighting factor is preferably the product of a main weighting factor, which reflects the influence of the individual measurement on wear, and an influence factor, which reflects the interaction with other measurements. By taking this interaction into account, a particularly realistic weighting of the individual measurements can be achieved.

[0029] For example, the medium temperature and the device temperature influence each other. The total settling time, for instance, affects the total flow rate.

[0030] According to one embodiment, the total settling time is weighted more heavily, in particular at least twice as heavily, in the index value compared to the weighting of the flow rate. The total settling time has a particularly strong impact on mechanical wear, which is more significant than the chemical wear caused by the total flow rate.

[0031] However, the weighting of the total flow rate depends primarily on the medium used. When using a particularly aggressive medium, the total flow rate can be weighted much more heavily than when using a less aggressive medium.

[0032] According to another embodiment, the age of the valve is incorporated into the index value in a weighted and corrected form. The age of the valve is considered, for example, from the date of manufacture. By taking the age of the valve into account, a general aging condition of the valve, such as material fatigue, is also considered.

[0033] A threshold value for the index, above which maintenance or replacement of the valve is recommended, can be individually defined based on the operating environment. This allows for consideration of environmental influences on wear. For example, a higher threshold value is set for use in a low-vibration environment than in an environment with strong vibrations. Similarly, the threshold value can be set taking the ambient temperature into account.

[0034] Another aspect is that the threshold value of the index, above which maintenance or replacement of the valve is recommended, can be determined based on the quality of the medium used. For example, the degree of contamination of the medium is taken into account when setting the threshold. In this way, the point at which maintenance is required can be determined even more precisely.

[0035] After maintenance and / or replacement of the valve, the threshold of the index value, above which maintenance or replacement of the valve is recommended, can be adjusted. This is particularly relevant if the degree of wear determined during maintenance differs from the degree of wear calculated based on the index value. This allows the predictive power of the index value to be gradually improved.

[0036] For example, the threshold is adjusted if the valve fails before the threshold has been reached, or if maintenance reveals that it was performed too early.

[0037] The object is further achieved according to the invention by a fluid control device with a valve, in particular a proportional valve, or a mass flow controller comprising a valve, in particular a proportional valve. The valve or the mass flow controller has a fluid housing in which a valve seat is formed, a closing element that interacts with the valve seat to open or close a flow path through the fluid housing, at least two units from a group comprising an operating time counter, a flow meter, a counter for recording the total actuation time of a valve plunger, a sensor for recording a medium temperature and a sensor for recording a device temperature, and an analysis unit configured to calculate an index value according to the method of the invention based on the measured values ​​of the existing units.

[0038] As already described in connection with the method according to the invention, various parameters with different physical units can be combined in this way to form a meaningful wear index, whereby a condition of the valve or of the mass flow controller comprising a valve can be determined without having to inspect the valve itself.

[0039] Further advantages and features of the invention will become apparent from the following description and the accompanying drawings. The drawings show: - Fig. 1 schematically a fluid control device according to the invention in the form of a mass flow controller, - Fig. 2 a table for calculating an index value according to a method according to the invention, and - Fig. 3 a table for calculating an adjustment factor, and - Fig. 4 a fluid control device according to the invention in the form of a valve.

[0040] Fig. Figure 1 schematically illustrates a fluid control device in the form of a mass flow controller 10.

[0041] A mass flow controller 10 can be used to regulate the mass flow of a medium to a setpoint. For this purpose, the mass flow controller 10 has an electronic controller 12 and a valve 14, in particular a proportional valve.

[0042] Furthermore, the mass flow controller 10 has a fluid housing 16 through which a fluid channel 18 runs. A valve seat 20 is formed in the fluid housing 16, more precisely in the fluid channel 18.

[0043] The closing element 22 is, for example, a membrane.

[0044] The valve seat 20 works together with a closing element 22, which is part of the valve 14, to open or close a flow path through the fluid housing.

[0045] Furthermore, the mass flow controller 10 includes the following units: an operating time counter 24, a flow meter 26, a counter 28 for recording a total actuation time of a valve plunger 30, a sensor 32 for recording a media temperature and a sensor 34 for recording a device temperature.

[0046] The total actuation time is, in particular, the accumulated time that the valve tappet 30 is in motion to open or close the valve 14.

[0047] In addition, the mass flow controller 10 includes an analysis unit 36, which is set up to evaluate the measured values ​​of the above-mentioned units 24, 26, 28, 32, 34.

[0048] Specifically, the analysis unit 36 ​​is set up to determine an index value I, based on which a degree of wear of the valve 14 is determined.

[0049] Typical wear parts include, for example, a valve diaphragm or a valve actuator, as well as electronic components.

[0050] The procedure for determining the index value I is described below based on the information in the Fig. 2 and Fig. The 3 tables shown are explained.

[0051] The table in Fig. Figure 2 illustrates the calculation of an index value I at a specific time t, at which the measured values ​​listed in the first column are available.

[0052] To be precise, the operating time counter 24 recorded an operating time of 20,000 h at time t.

[0053] The flow rate measured by the flow meter 26, which in the exemplary embodiment is given in relation to a maximum flow rate in l / min, is 100,000 min.

[0054] The maximum flow rate in the exemplary embodiment is 1000 l / min.

[0055] This means that, in the exemplary embodiment, 100,000,000 liters have flowed through the mass flow controller 10 at time t.

[0056] The time recorded by the counter 28 for recording the total actuation time of a valve tappet 30 is 10,000 h.

[0057] The media temperature measured by sensor 32 is 40°C.

[0058] The device temperature measured by sensor 34 is also 40°C.

[0059] However, the values ​​given are only examples.

[0060] The various parameters have different effects on the wear of the mass flow controller 10 or the valve 14 contained in the mass flow controller 10.

[0061] Operating time has a particular impact on the wear and tear of the electronics and sensors, with the load being a thermal load.

[0062] The flow rate reflects a chemical load, which also promotes the wear and tear of the electronics and sensors.

[0063] The total actuation time recorded by counter 28 reflects a mechanical load. In particular, the total actuation time corresponds to the time that the moving parts of valve 14 are in motion.

[0064] The temperature measured by sensor 34 to detect a device temperature affects the wear of the electronics, while the temperature measured by sensor 32 to detect the media temperature affects the wear of the sensor technology.

[0065] In both cases, the stress is thermal.

[0066] The age of valve 14, from which maintenance or replacement of valve 14 is recommended, is also included in the index value.

[0067] The recorded measurements are multiplied by a weighting factor and a correction factor specific to each measurement, and then the individual weighted and corrected measurements are added together to form the index value I.

[0068] The age of valve 14 is also included in the index value in a weighted and corrected form.

[0069] The weighting factor and the correction factor are in Fig. 2 are specified for the respective measured values.

[0070] The values ​​of the weighting factor and the correction factor preferably remain constant during the operating time of the mass flow controller 10.

[0071] In the exemplary embodiment, the weighting factor is the product of a main weighting factor, which reflects the influence of the individual measured value on the wear, and an influencing factor, which reflects the interaction with other measured values.

[0072] Example values ​​for the main weighting factor and the influence factor are shown in the table in Fig. 2 is given.

[0073] The main weighting factor, for example, takes values ​​between zero and ten.

[0074] In the exemplary embodiment, the total actuation time is weighted more heavily, in particular at least twice as heavily, in the index value compared to the weighting of the flow rate. This is because the movement of the valve stem 30 causes more wear than the flow of the medium.

[0075] The influence factor takes values ​​between zero and one.

[0076] The table shows that the medium temperature and the device temperature influence each other, which is clear since the medium is in contact with the device and thus heat transfer can take place.

[0077] The total settling time has an influence on the flow rate measured by flow meter 26.

[0078] The influencing factor is optional; the weighting can also be done sufficiently accurately using only the main weighting factor.

[0079] In the exemplary embodiment, the correction factor is the product of an adjustment factor and a linearization factor, where the linearization factor is optional.

[0080] The linearization factor is used to linearize the curve of the individual measured values.

[0081] The linearization factor can be based on a mathematical function.

[0082] The calculation of the adjustment factor is taken from the table in Fig. 3 stands out.

[0083] Specifically, the adjustment factor for the individual measured values ​​is determined by dividing a defined base value, which is identical for all available units, by a limit value defined for the respective unit.

[0084] In this example, the base value is 100.

[0085] The defined limit value corresponds in particular to a recommended maximum operating limit.

[0086] Applying the weighting factor and correction factor described above, an index value I of 1.045 is calculated at time t.

[0087] The index value is a dimensionless value.

[0088] If the index value exceeds a threshold, maintenance or replacement of certain wear parts is recommended.

[0089] In the exemplary embodiment, no service requirement is seen if the index value I is below 1000.

[0090] A review is recommended if the index value I is between 1000 and 1200.

[0091] If the index value is above 1200, replacement is recommended.

[0092] However, the threshold can be individually determined depending on the application and / or location.

[0093] For example, the threshold of the index value I, from which maintenance or replacement of valve 14 is recommended, can be determined based on the quality of the medium used, in particular depending on the degree of contamination of the medium.

[0094] The index value I can also be adjusted and thus optimized over time. For example, after maintenance and / or replacement of valve 14, the threshold value of index I, above which maintenance or replacement of valve 14 is recommended, can be adjusted.

[0095] The idea according to the invention is not limited to application in a mass flow controller 10, but the idea can also be applied to a stand-alone valve 14, in particular to a process valve, as is the case in Fig. 3 is illustrated.

[0096] For identical structures with identical functions known from the above embodiment, the same reference numerals are used below, and reference is made to the preceding explanations.

[0097] In the case of a standalone valve 14, the analysis unit 36 ​​is housed in a control head 38 of the valve.

Claims

[1] Method for operating a fluid control device in the form of a valve (14) or a mass flow controller (10) comprising a valve (14), with a fluid housing (16) in which a valve seat (20) is formed, a closing element (22) which interacts with the valve seat (20) to open or close a flow path through the fluid housing (16), and with at least two units from a group comprising an operating time counter (24), a flow meter (26), a counter (28) for recording a total actuation time of a valve plunger (30), a sensor (32) for recording a medium temperature, and a sensor (34) for recording a device temperature, wherein the measured values ​​recorded by the units are multiplied by a weighting factor and a correction factor individual to the respective measured value,wherein the individual weighted and corrected measured values ​​are added together to form an index value (I), and wherein a degree of wear of the valve (14) is determined based on the index value (I). [2] Method according to claim 1, characterized by , that the correction factor contains an adjustment factor, wherein the adjustment factor for each measured value is determined by dividing a defined base value, which is identical for all existing units, by a limit value defined for the respective unit. [3] Method according to any one of the preceding claims, characterized by , that the correction factor contains a linearization factor, by means of which the course of the individual measured values ​​is linearized. [4] Method according to any one of the preceding claims, characterized by, that the weighting factor is the product of a main weighting factor, which reflects the influence of the individual measurement on wear, and an influencing factor, which reflects the interaction with other measurements. [5] Method according to any one of the preceding claims, characterized by , that the total settling time is included in the index value with a higher weighting compared to the weighting of the flow rate, in particular with a weighting at least twice as high. [6] Method according to any one of the preceding claims, characterized by , that the age of the valve (14) is included in the index value (I) in a weighted and corrected form. [7] Method according to any one of the preceding claims, characterized by , that a threshold value of the index value (I), above which maintenance or replacement of the valve (14) is recommended, is individually determined based on the place of use. [8] Method according to any one of the preceding claims, characterized by , that the threshold of the index value (I) above which maintenance or replacement of the valve (14) is recommended is determined based on the quality of the medium used. [9] Method according to any one of the preceding claims, characterized by , that after maintenance and / or replacement of the valve (14) the threshold of the index value (I) from which maintenance or replacement of the valve (14) is recommended is adjusted. [10] Fluid control device comprising a valve (14), in particular a proportional valve, or a mass flow controller (10) having a valve (14), with a fluid housing (16) in which a valve seat (20) is formed, a closing element (22) which cooperates with the valve seat (20) to release or close a flow path through the fluid housing (16), at least two units from a group comprising an operating time counter (24), a flow meter (26), a counter (28) for recording a total actuation time of a valve plunger (30), a sensor (32) for recording a medium temperature and a sensor (34) for recording a device temperature, and with an analysis unit (36) which is configured to calculate an index value (I) on the basis of the measured values ​​of the existing units according to a method according to one of the preceding claims.

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