DE102019105515A1 - Diaphragm control valve - Google Patents

Abstract

The invention relates to a diaphragm control valve comprising a diaphragm valve and a valve control. The diaphragm valve has a valve housing with a flow channel, a diaphragm and an actuator. The valve control comprises an actuator (16). The valve control comprises a correction element (12) and holds a plurality of predefined correction characteristic curves (120). The valve control is set up in such a way that a user can select one of the correction characteristics (120) and the correction element (12) with the selected correction characteristic (120) determines a corrected position target value (CMD *) from a predetermined position target value (CMD). The actuator (16) is designed to determine a manipulated variable (CTRL) from the corrected position setpoint (CMD *) and to control the actuator with the manipulated variable (CTRL) in such a way that the diaphragm control valve has a predetermined diaphragm control valve characteristic.

Description

The invention relates to a diaphragm control valve.

Seat valves with a linear or equal-percentage valve characteristic are often used as control valves. Such a seat valve is for example from DE1828930U known.

Diaphragm valves, as in the DE102016124805A1 disclosed, are in turn known for the fact that, due to their extremely non-linear valve characteristics, they can only be used as a control valve in exceptional cases, since processes can only be controlled with difficulty or not at all. If a diaphragm valve is to be used as a control valve, a special form of diaphragm valve can be used today, as is exemplified in FIG DE102015205127A1 and DE102013215294A1 are disclosed. Particularly shaped parabolic cone-shaped membranes are used here. The valve characteristic is set via the design of the diaphragm, in particular via the shape of the diaphragm. In the above-mentioned diaphragm control valves, the shape of the parabolic cone essentially corresponds to the control cone from FIG DE1828930U . Adaptation of the valve characteristic therefore requires the membrane to be removed and replaced. This is associated with a lot of effort and may lead to longer business interruptions.

The invention is based on the object of overcoming the disadvantages of the existing solutions.

The object is achieved according to the invention by the subject matter of the independent claim.

The diaphragm control valve according to the invention comprises a diaphragm valve and a valve control. The diaphragm valve has a valve housing with a flow channel, a diaphragm and an actuator. The membrane prevents fluid from leaking out of the flow channel or from being contaminated. The membrane seals the flow channel from the actuator.

The valve control comprises at least one actuator. The actuator can comprise a position controller and a position control loop.

According to one aspect, the valve control comprises a correction element. The valve control, in particular the correction element, can hold a plurality of predefined correction characteristics. The correction characteristics can include correction information.

According to a further aspect, the valve control can be set up in such a way that a user can select one of the correction characteristics and the correction element with the selected correction characteristic determines a corrected position desired value from a predetermined position desired value.

According to a further aspect, the actuator can be designed to determine a manipulated variable from the corrected nominal position value and to use the manipulated variable to control a drive part of the diaphragm control valve, in particular an actuator. Based on the manipulated variable, the actuator assumes a specific functional position, which ultimately determines the flow rate of the diaphragm control valve.

The above aspects achieve that the diaphragm control valve has a predetermined diaphragm control valve characteristic. The diaphragm control valve characteristic describes the behavior of the diaphragm control valve. The diaphragm control valve characteristic can be changed by selecting the correction characteristic. The diaphragm valve characteristic shows the dependence of the Kv value on the stroke (or the position setpoint) of the diaphragm control valve. The Kv value is understood to be the flow rate in m ³ / h of water at 5 - 30 ° C, which passes through the valve at the respective stroke at a pressure loss of 1 bar. The Kv value is therefore a flow rate based on the specified standard conditions. In other words, the diaphragm control valve characteristic can be understood as the dependence of the Kv value on the stroke of the actuator. The diaphragm control valve characteristic is in turn formed from the diaphragm valve characteristic and the correction characteristic. Control valves are usually designed with either an equal percentage or a linear characteristic. The equal percentage characteristic is characterized in that the same stroke changes require the same percentage changes in the respective Kv value. With a linear characteristic, the same changes in stroke cause the same changes in the Kv value. Actuators convert the control signal, which comes from a positioner or an actuator, for example, into a stroke movement of the control valve (plug stem with valve plug).

According to an advantageous aspect, the diaphragm control valve can additionally include a process controller. In particular, the process controller can be part of the valve control. The process controller can be designed to determine the (predetermined) position setpoint from a process setpoint and a process actual value. The diaphragm control valve is therefore advantageously set up in such a way that a deviation of the process actual value from the process setpoint value can be determined so that a position setpoint value can be determined and ultimately the deviation can be compensated for. The position setpoint can be corrected based on the selected correction characteristic (as a corrected position setpoint).

According to an advantageous aspect, the process controller can continuously output a desired position value to the correction element. The position setpoint correlates with a position of the diaphragm valve. The position setpoint is in a range that corresponds to a valve position between fully open and fully closed. A corresponding sensor (e.g. position sensor) can then record and output the actual position values of the diaphragm valve (e.g. an actuator of the diaphragm valve). A process sensor can record an actual process value that can be fed back to the process controller. The process sensor can, for example, be a Pt100 temperature sensor whose output signal can be fed to the process controller. Alternatively, however, the process sensor can also comprise a transmitter which forwards a converted or standardized sensor signal to the process controller. Typical process sensors measure a physical quantity of a medium, such as flow rate, pressure, temperature, pH value or conductivity.

Due to the mostly non-linear relationships between the diaphragm valve position and the actual process value, the desired position value generated by the process controller can be adapted to a corrected desired position value using the method according to the invention. The adjustment is done with the help of the correction element. Correction values (correction characteristic curve) based on determined value pairs of actual position values and actual process values can be stored in the correction element. With the correction values, corrected desired position values can be calculated directly on the correction element from the received uncorrected (predetermined) desired position values. The corrected position setpoints are used to compensate for the non-linearities of the diaphragm valve characteristic curve of the diaphragm valve, so that a linear overall behavior of the controlled system is achieved. This increases the overall control quality. The correction process can be restarted if the process changes or if components of the process control loop are changed or replaced.

According to a further advantageous aspect, the diaphragm control valve can comprise a position control loop. The position control loop can include the actuator, a position controller and a sensor, in particular a position sensor. The position sensor can be set up to determine a position (actual position value) of a component of the diaphragm control valve that determines the flow rate, in particular of the actuator. The position sensor can be set up to transmit the specific position (actual position value) to the positioner. The position controller can also be set up to receive the corrected nominal position value from the correction element. The position controller can then be designed in such a way that it determines the deviation (control difference) of the actual position value from the corrected position setpoint and provides the manipulated variable based on the deviation (control difference). The manipulated variable can then be output from the actuator to the drive part of the diaphragm control valve, in particular the actuator. Depending on the control difference between the corrected position setpoint and the actual position value, the positioning system can e.g. the membrane valve can be ventilated or vented.

According to a further advantageous aspect, the plurality of correction characteristics can have a correction characteristic for a linear control characteristic of the diaphragm control valve and / or at least one further correction characteristic for an equal-percentage control characteristic of the diaphragm control valve. The control characteristic of the equal percentage can in particular have values of GP = 1: 25, 1:33, 1:50, 25: 1, 33: 1 and / or 50: 1. The plurality of correction characteristics advantageously includes all of the stated correction characteristics. The control characteristic of equal percentage is defined, for example, in DIN EN 60534 for control valves. In this way, the diaphragm valve can advantageously be used as a diaphragm control valve. Structural changes to the diaphragm valve are not necessary.

According to a further advantageous aspect, the plurality of correction characteristics can each include sets of correction characteristics for different membrane types. In particular, the sets can each have a correction characteristic for a linear control characteristic and / or at least one correction characteristic for an equal-percentage control characteristic. This aspect enables the membrane to be replaced quickly and easily. By changing the selected correction characteristic, a (different) linear or equal percentage diaphragm control valve characteristic can be impressed on the diaphragm control valve in a simple manner. Likewise, the same diaphragm control valve characteristic can be obtained despite a change of the diaphragm type.

According to a further advantageous aspect, the sets can each include correction characteristic curves for membranes that contain in particular polytetrafluoroethylene (PTFE) or ethylene-propylene-diene rubber (EPDM) or fluororubber (FKM). This choice of material has been found to be particularly suitable, e.g. to get a hygienic flow channel.

According to a further advantageous aspect, the membrane can have a first partial area Form the channel wall of the flow channel. A second partial area of the channel wall can form a valve seat. In cooperation with the valve seat, the membrane can define a (free) flow cross section of the flow channel. The actuator can be designed to deflect the membrane and thus to vary the flow cross section between a minimum flow cross section and a maximum flow cross section. These valves are also known as deep seat diaphragm valves and web seat diaphragm valves. The minimum flow cross section can advantageously be zero. In this case the valve is closed. According to this aspect, the membrane seals the flow channel from the environment, in particular from the actuator.

According to a further advantageous aspect, the second partial area of the duct wall can form a web. In other words, the diaphragm valve can be a web seat diaphragm valve.

In the context of the present invention, the position controller can be part of an optionally available position control loop. This includes the positioner, the actuator, the diaphragm valve and a position sensor, which are constructed as a position control circuit in a closed loop. For example, the current position (i.e. the actual position value or stroke) of the (pneumatic) drive of the diaphragm valve (e.g. the actuator) can be recorded via the position sensor. The positioner compares the actual position value with the corrected position setpoint specified as a standard signal. If there is a control difference, this is compensated for by the actuator, for example by venting a pneumatically operated drive. In this way, the position of the drive is changed until the system deviation is zero. The position control loop can also be integrated into a process control loop and thus represent a subordinate auxiliary control loop. This results in a so-called cascade control. The process control loop then includes, for example, the process controller (optional), the position control loop, and the process from which a process variable or a process parameter is fed back to the process controller, for example by means of the process sensor. If there is a control difference between the process actual value and the process setpoint, this can be compensated in the process control loop. The process control loop can be seen as the main control loop in this situation. The process controller in the process control loop can, for example, have a PID function (Proportional Integral Derivative Controller; controller with proportional element, integrating element and differentiating element). The process setpoint is specified as the setpoint. The actual process value is recorded via sensors and, if necessary, transmitters. This process actual value is compared by the process controller with the setpoint it has specified. If there is a control difference, the position setpoint for the correction element is changed. With the help of the correction element, the specified nominal position value is corrected into a corrected nominal position value using a correction characteristic curve, so that the actuator of the diaphragm valve is set via the actuating system until, in the ideal case, the control difference in the process control loop is zero.

Advantageously, according to one aspect of the invention, when determining corrected desired position values based on the determined value pairs of actual position values and actual process values, a complete correction characteristic is determined. The determination can take place independently of the individual diaphragm valve in the context of a corresponding series of tests. Several resulting correction characteristics for membranes of the same type can be averaged. This improves the database. According to this aspect of the invention, the determined value pairs of actual position values and actual process values (in a test environment) are transformed into a corresponding correction characteristic in such a way that the series connection of the diaphragm valve characteristic and the correction characteristic leads to a largely linear or equal percentage overall behavior.

• - 1 eine vereinfachte Darstellung einer Regelstrecke gemäß Aspekten der Erfindung zeigt,
• - 2 eine vereinfachte Darstellung einer Regelstrecke mit Prozessregler gemäß Aspekten der Erfindung zeigt,
• - 3a eine vereinfachte Darstellung eines Membranventils mit Stellungsregelkreis gemäß Aspekten der Erfindung zeigt,
• - 3b eine vereinfachte Darstellung eines Membranventils ohne Stellungsregelkreis gemäß Aspekten der Erfindung zeigt,
• - 4 eine vereinfachte Darstellung einer Linearisierung eines Anlagenprozesses gemäß Aspekten der Erfindung zeigt,
• - 5 eine vereinfachte beispielhafte Berechnung einer Korrekturkennlinie gemäß Aspekten der Erfindung zeigt.

Further features and advantages of the invention will become clear on the basis of the following description of the preferred exemplary embodiments of the invention with reference to the accompanying figures, wherein

• - 1 shows a simplified representation of a controlled system according to aspects of the invention,
• - 2 shows a simplified representation of a controlled system with process controller according to aspects of the invention,
• - 3a shows a simplified representation of a diaphragm valve with position control circuit according to aspects of the invention,
• - 3b shows a simplified representation of a diaphragm valve without a position control loop according to aspects of the invention,
• - 4th shows a simplified representation of a linearization of a plant process according to aspects of the invention,
• - 5 shows a simplified exemplary calculation of a correction characteristic in accordance with aspects of the invention.

In 1 a simplified representation of a controlled system according to aspects of the invention is shown. The controlled system includes the correction characteristic curve 120. The correction characteristic curve 120 is used within the correction element 12 to produce a specified position setpoint CMD to determine a corrected position setpoint CMD *. The controlled system also includes the diaphragm valve characteristic curve 130 and the system characteristic curve 140. The diaphragm valve characteristic curve 130 and the correction characteristic curve 120 together form the diaphragm control valve characteristic curve 150 . A diaphragm valve 8th (not shown) has a diaphragm valve characteristic curve 130 which is dependent on its construction.

The membrane valve characteristic curve 130 is dependent on various factors, for example on the material and the shape of the membrane 40 and on the shape and surface of the flow channel 41 of the valve housing 42. The membrane materials used are, for example, PTFE, EPDM or FKM. When designing the housing, the type of housing (e.g. Saunders contour) and the type of manufacture of the housing (e.g. tubular housing, cast housing, etc.) are particularly important. There are various transitions, edges and projections in the housing, depending on the manufacturing and design, which influence the flow rate Q depending on the actual position value POS. The shape of the diaphragm valve characteristic curve 130 is also dependent on the nominal width of the valve housing 42. As a result, the diaphragm valve characteristic curves 130 are highly non-linear. The diaphragm valve characteristic curve 130 therefore influences the system characteristic curve 140 as a function of the flow rate Q. The process actual value PV results from the system characteristic curve 140.

While the diaphragm valve characteristic curve 130 is determined by the design and is therefore fixed, the correction characteristic curve 120 and thus also the resulting diaphragm control valve characteristic curve 150 can be selected according to the invention by an operator as a function of the system characteristic curve 140.

The correction characteristics 120, from which the operator can choose, can be determined or calculated experimentally through test series. This is explained in more detail in the description of 5 executed.

2 shows a simplified representation of a controlled system according to aspects of the invention with a process control loop. The process control loop includes a process controller 20th and a process sensor 5 . The process actual value PV is derived from the process or a process variable, for example a pressure, a temperature, etc. The deviation between the process setpoint SP and the process actual value PV is the control difference Xd2. The control difference Xd2 is determined by the process controller 20th determines which outputs a (specified) position setpoint CMD based on it.

According to this exemplary embodiment, a correction stage 12 is provided, which is connected downstream of the conventional process controller. The output of the process controller 20th is in connection with correction element 12, to which the predetermined position setpoint value CMD is transmitted. The correction values (for example CMD * / CMD) or the complete correction characteristic 120 and / or their parameters are stored (stored) in the correction element 12. The uncorrected (predetermined) nominal position values CMD are converted in the correction element 12 into corrected nominal position values CMD *. The resulting flow rate Q of the diaphragm valve is then obtained from the corrected setpoint position value CMD * and the diaphragm valve characteristic curve 130 8th according to the diaphragm control valve characteristic 150 . A control element 16 provides a manipulated variable CTRL based on the corrected setpoint position value CMD * (in 2 not shown), so that the corrected position setpoint CMD * acts on the process via the valve opening and thus influences the actual process value PV. The current process actual value PV is derived from the process, from the process sensor 5 and to an input of the process controller 20th returned. The process sensor can send signals directly to the process controller 20th transmit or via a transmitter. The process controller 20th In this exemplary embodiment, the process control loop (main control loop) can have a PID function. Overall, the control difference Xd2 is minimized by the control loop.

3a shows a simplified representation of a diaphragm valve 8th according to aspects of the invention with an electromotive or pneumatic drive. A diaphragm valve is shown 8th with an associated valve control which includes the positioner 7. The diaphragm valve 8th regulates a fluid flow within a flow channel 41 . At least one parameter of the fluid flow (for example flow rate) is measured by means of a process sensor 5 detected. This is then the process actual value PV. In addition, the diaphragm control valve also includes the position sensor 9.

The diaphragm valve 8th includes a position control loop 3 , which comprises at least the position controller 7, the actuator 16, the position sensor 9 and the actuator 43. With the position control loop 3 it is an auxiliary control loop, which can be optionally present. The actuator 16 for the actuator 43 can also be part of the position controller 7. A control system can be formed by the position control loop or by the position controller 7 and / or the actuator 16, which also has valves for pressurizing and venting the drive of the diaphragm valve 8th may include. It converts the output variable of the positioner 7 into the corresponding control variables for the actuator 43 of the diaphragm valve 8th around. The position sensor 9 can also be located outside the device. As stated previously, the position control loop receives 3 or the positioner 7 a corrected position setpoint value CMD * from correction element 12.

The position controller 7 sends a control signal CTRL to the drive of the diaphragm valve 8th from or to the actuator 43 of the diaphragm valve 8th . Based on the control signal CTRL, the actuator 43 will assume a specific functional position, as a result of which a specific valve opening of the diaphragm valve will open 8th results. The diaphragm valve acts via the diaphragm 40 and the housing 42 8th with the flow channel 41 together so that a resulting flow rate Q results. The actual position value POS of the drive of the diaphragm valve can be measured by means of a position sensor 9 8th be determined. The actual position value POS can also be defined by the position of the actuator 43. This actual position value POS is compared with the desired position value CMD * corrected externally by the correction element 12. A control difference is thus determined by the position controller 7, which in turn is converted into a corresponding control signal CTRL for the process valve 8th is converted to output from the actuator.

In other words, the diaphragm control valve comprises a diaphragm valve 8th and a valve control. The diaphragm valve 8th has a valve housing 42 with a flow channel 41 , a membrane 40 and an actuator 43. The valve control comprises a correction element 12 and the position controller 7. The valve control can optionally also be a process controller 20th exhibit. The correction element 12 holds a plurality of predefined correction characteristic curves 120. The valve control is set up in such a way that a user can use the man-machine interface 45 and a menu 46 can select one of the correction characteristic curves 120. The correction element 12 determines corrected position setpoint values CMD * with the selected correction characteristic curve 120. The position controller 7 is designed to determine a manipulated variable CTRL from the corrected setpoint position value CMD *, the manipulated variable CTRL being used by the actuator 16 to control the actuator 43. This means that the diaphragm control valve has a predetermined characteristic diaphragm control valve curve 150 having.

Overall, this results in a cascade configuration of a process control loop with a position controller 7, as is also used in accordance with the aspects of the present invention.

The plurality of correction characteristics 120 have at least one correction characteristic 120 for a linear control characteristic and / or at least one correction characteristic 120 for an equal-percentage control characteristic, in particular with values of GP = 1: 25, 1:33, 1:50, 25: 1, 33: 1 and / or 50: 1.

The plurality of correction characteristics 120 each include sets of correction characteristics 120 for different membrane types. The sets each have at least one correction characteristic 120 for a linear control characteristic and / or at least one correction characteristic 120 for an equal-percentage control characteristic.

The sets each contain correction characteristics 120 for diaphragms 40, which in particular contain polytetrafluoroethylene (PTFE), ethylene-propylene-diene rubber (EPDM) or fluororubber (FKM).

The membrane 40 forms a first partial area of a channel wall of the flow channel. A second sub-area of the duct wall forms a valve seat. The membrane 40, interacting with the valve seat, defines a flow cross section A. of the flow channel 41 . The actuator 43 is designed to deflect (deform) the membrane 40 and thus the flow cross section A. to vary between a minimum flow area and a maximum flow area. The minimum flow cross-section is zero. The valve then blocks.

The second partial area of the channel wall can form a web so that it can accordingly be a web seat diaphragm valve.

The diaphragm control valve characteristic curve predetermined by the diaphragm valve characteristic curve 130 and the correction characteristic curve 120 150 of the diaphragm control valve is linear or equal percentage.

3b shows a simplified representation of a diaphragm valve 8th according to aspects of the invention with an electromagnetic drive. The diaphragm valve 8th does not have a position sensor 9 in this embodiment. The diaphragm valve 8th therefore advantageously does not include a position control loop 3 so that the corresponding components are dispensed with. The actuator 16 determines the control signal CTRL from the corrected setpoint position value CMD *, which is output to the drive of the solenoid valve.

In 4th a simplified representation of a linearization of a plant process according to aspects of the invention is shown. The relationships are explained using a membrane valve with a PTFE membrane. It can be seen that through a suitable choice of the correction characteristic 120a a linearization of the plant process is achieved. A linear process curve 160 of the system results from the combination of the system characteristic 140a with the PTFE diaphragm control valve characteristic 150a . The PTFE diaphragm control valve characteristic 150a , or the corresponding PTFE correction characteristic 120a is made by the user from the predefined PTFE correction characteristics 120a selected. To determine the PTFE correction characteristics 120a can the PTFE diaphragm control valve characteristic 150a to compensate for the characteristic curve of the PTFE diaphragm valve 130a of the diaphragm valve 8th can be calculated.

In the example, PTFE correction characteristics for linear behavior and equal-percentage behavior with 1:25, 1:33, 1:50, etc. are determined in this way. These PTFE correction characteristics are stored together with the selectable diaphragm control valve characteristics, for example as M-PTFE-LIN, M-PTFE-GP1: 25, M-PTFE-GP1: 33 etc. (in correction element 12).

If the user equips a diaphragm control valve according to the invention with a PTFE diaphragm and uses it in a system with GP25: 1 behavior, only the corresponding M-PTFE-GP1: 25 diaphragm control valve characteristic or the corresponding correction characteristic must be selected. From the combination of the selected PTFE correction characteristic 120a and the fixed PTFE diaphragm valve characteristic 130a the result is a corresponding characteristic curve of the PTFE diaphragm control valve 150a with equal percentage GP1: 25 behavior. In combination with the GP25: 1 behavior of the system according to the system characteristic curve 140a, the overall result is a linear behavior corresponding to the process characteristic curve 160 the plant.

In 5 An exemplary calculation of a correction characteristic 120 in accordance with aspects of the invention is shown. The calculation of the diaphragm control valve characteristics is explained here using the example of a diaphragm valve with a PTFE diaphragm. Several PTFE diaphragm valve characteristics are measured 130a several diaphragm valves with PTFE diaphragm added. The PTFE diaphragm valve characteristics 130a are averaged so that a non-linear averaged PTFE diaphragm valve characteristic curve 130a is produced. From the averaged PTFE diaphragm valve characteristic 130a becomes a PTFE correction characteristic 120a for linear behavior of the PTFE diaphragm control valve characteristic 150a generated. Not shown, but in the same way, several PTFE correction characteristics can be used 120a can be determined for equal-percentage behavior of the diaphragm control valve characteristic. Correspondingly, linear diaphragm control valve characteristics or correction characteristics and equal percentage diaphragm control valve characteristics or correction characteristics are generated (calculated) in advance for various diaphragm materials.

In the diagram, the flow rate Q is plotted against the actual position value POS. Here, POS denotes the position of the actuator as a percentage of the stroke and thus a measure of the valve opening. POS = 0% means that the valve seat is (completely) closed. POS = 100% means that the valve is fully open. POS values between 0% and 100% denote the percentage (proportional) position of the actuator or the percentage (proportional) opening of the valve seat, in each case based on the maximum open valve. The flow rate Q is also plotted in percent. Q = 0% means that the valve seat is completely closed and there is no flow. Q = 100% means that maximum flow occurs. The valve seat is fully open at Q = 100%. Values of Q between 0% and 100% denote the percentage (proportional) flow related to the maximum flow. The PTFE correction characteristics 120a are calculated using the inverse (the inverse function). By referring to 4th The explained procedure results in a linear behavior of the PTFE diaphragm control valve characteristic 150a .

List of reference symbols

5

Process sensor

7th

Positioner

8th

Diaphragm valve

9

Position sensor

12

Correction link

16

Actuator

20th

Process controller

40

membrane

41

Flow channel

42

Valve body

43

Actuator

45

Man-machine interface

46

menu

120

Correction curve

120a

PTFE correction characteristic

130

Diaphragm valve characteristic

130a

PTFE diaphragm valve characteristic

140

System characteristic

140a

PTFE system characteristic

150

Diaphragm control valve characteristic

150a

Characteristic curve of PTFE diaphragm control valve

160

Process curve

A.

Flow cross-section

CMD

Preset position setpoint

CMD *

Corrected position setpoint

CTRL

Manipulated variable

POS

Actual position value

PV

Process actual value

Q

Flow

SP

Process setpoint

Xd2

Control difference

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 1828930 U [0002, 0003]
• DE 102016124805 A1 [0003]
• DE 102015205127 A1 [0003]
• DE 102013215294 A1 [0003]

Claims (9)

Diaphragm control valve, comprising a diaphragm valve (8) and a valve control; wherein the diaphragm valve (8) has a valve housing (42) with a flow channel (41), a diaphragm (40) and an actuator (43), the valve control comprising an actuator (16) and a correction element (12) and a plurality of pre-defined correction characteristics (120), and wherein the valve control is set up in such a way that a user can select one of the correction characteristics (120) and the correction element (12) with the selected correction characteristic (120) generates a corrected position target value (CMD) from a predetermined position target value (CMD). CMD *) determined; and wherein the actuator (16) is designed to determine a manipulated variable (CTRL) from the corrected nominal position value (CMD *) and to control the actuator (43) with the manipulated variable (CTRL) in such a way that the diaphragm control valve has a predetermined diaphragm control valve characteristic (150) having. Diaphragm control valve according to Claim 1 , the valve control additionally comprising a process controller (20), the process controller being designed to determine the position setpoint (CMD) from a process setpoint (SP) and an actual process value (PV). Diaphragm control valve according to one of the Claims 1 and 2 , wherein the plurality of correction characteristics (120) have a correction characteristic (120) for a linear control characteristic and / or at least one correction characteristic (120) for an equal-percentage control characteristic, in particular with values of GP = 1: 25, 1:33, 1:50, 25: 1, 33: 1 and / or 50: 1. Diaphragm control valve according to one of the Claims 1 to 3 , the plurality of correction characteristics (120) each comprising sets of correction characteristics (120) for different membrane types, in particular the sets each having a correction characteristic (120) for a linear control characteristic and / or at least one correction characteristic (120) for an equal percentage control characteristic. Diaphragm control valve according to Claim 4 , the sets each comprising correction characteristic curves (120) for membranes (40) which contain in particular polytetrafluoroethylene (PTFE) or ethylene-propylene-diene rubber (EPDM) or fluororubber (FKM). Membrane control valve according to one of the preceding claims, wherein the membrane (40) forms a first sub-area of a channel wall of the flow channel, a second sub-area of the channel wall forming a valve seat, and wherein the membrane (40) cooperates with the valve seat to form a flow cross section (A) of the flow channel (41), wherein the actuator (43) is designed to deflect the membrane (40) and thus to vary the flow cross section (A) between a minimum flow cross section and a maximum flow cross section. Diaphragm control valve according to Claim 6 , wherein the second portion of the duct wall forms a web. Diaphragm control valve according to one of the preceding claims, the diaphragm control valve characteristic (150) of the diaphragm control valve predetermined by the diaphragm valve characteristic curve (130) and the correction characteristic curve (120) being linear or equal-percentage. Diaphragm control valve according to one of the preceding claims, wherein the diaphragm control valve is designed such that the user can select one of the correction characteristics (120) by means of a menu (46), in particular via a man-machine interface (45).

Images