DE202010010267U1 - Torsionsmesskupplung - Google Patents

Abstract

Coupling (100) for rotary actuators for transmitting force, wherein the coupling between the drive (40), in particular a servomotor, and a control device (41), in particular a valve, flap or rotary control valve is arranged, characterized in that the coupling (100) at least a measuring unit (200) for adjusting power and at least one evaluation unit (300) or a connecting device for connecting the measuring unit (200) to an external evaluation unit (300).

Description

The The invention relates to a coupling for rotary actuators for transmission of restoring forces between the drive and the control device.

In In the industry, couplings for rotary actuators are being transmitted the restoring forces between the drive and a control device used. In larger plants find common a large number of couplings, which differ in different Make a chemical production plant or other Production methods are used, use. Dependent the field of application can have different problems, Faults or errors occur. Examples for possible errors or malfunctions broken waves, wear, air loss, leakage, defective seat rings, increased corrosion, foreign matter in the fitting or fixed stuffing boxes. To possible Error cases and malfunctions early it is to recognize and to avoid possible damages necessary, the individual couplings and drives and control devices, such as B. fittings, at regular intervals during operation on their correct functioning to check. It must z. B. the valve seat be checked, as well as the ability to lock the built-in fittings are controlled. It can happen that different reviews only in off or removed condition can be performed and thus unnecessary production losses comes. Furthermore, in case of any disturbances or errors to fix the causes repairs as well as maintenance tasks be performed. As it is not possible in any case is, the actual cause of an occurring disorder Immediately recognizing it can be dangerous to humans Repair tasks come. For safety's sake it is further necessary, at regular intervals Perform maintenance tasks on the couplings.

From the prior art z. B. by the DE 90 02 877 U1 temporary test equipment for sporadic measurement and setting of endpoints known. However, such testers have the disadvantage that they are not an integral part of the coupling and thus do not allow continuous and continuous measurement. Since these are portable testers, the measuring accuracy of such measuring instruments is too inaccurate for safety-relevant testing in an industrial plant.

Of the Invention is based on the object, a coupling for power transmission for rotary actuators with additional integrated Function for increasing process reliability and operational safety the entire operating time, to provide the coupling with additional functionality a reduction of the maintenance effort or extension the maintenance intervals, minimization of downtime and a Function for accident prevention during maintenance has.

Solved This object is achieved with a clutch according to the Features of claim 1.

Hereinafter, the above-mentioned coupling for rotary actuators on an additional measuring unit for Stellkraftermittlung. The coupling according to the invention serves for actuating force transmission for rotary actuators, z. B. to transfer the forces between actuator and a valve. During operation of the coupling, the measuring unit continuously measures all occurring forces between the drive and the valve. As a result, the measuring unit, which is an integral part of the coupling, constitutes a continuous measuring device. In addition to the measuring unit, the coupling has an evaluation unit or a connecting device for an external evaluation unit. Due to the continuous measurement and evaluation of the restoring forces between the drive and the valve, a variety of faults or malfunctions can be detected at an early stage with the clutch according to the invention, thus avoiding serious damage. Furthermore, thus can be determined and observed with the coupling according to the invention, the qualitative condition of the valve and the drive. Thus, with the clutch according to the invention, inter alia, contact forces on a valve seat can also be measured when installed and, consequently, it can be determined whether the locking capability of built-in valves is still present. The measured forces are compared with the forces during normal operation. Occur z. B. increased forces during normal operation, which go beyond the breakaway torque, this may cause such. B. defective seat rings, hardened product, foreign bodies in the valve, stuck glands, increased corrosion or other causes include. Exemplary causes in the occurrence of smaller forces compared to the normal operation can, for. As broken waves, slackening of the driving force in the rotary drive, air losses by Undich activity, wear or other causes. In addition to the monitoring of the function and fault detection or detection of faults, the coupling of the invention also serves to increase the reliability, to prevent unnecessary production losses, to reduce maintenance and accident prevention in maintenance. For example, in a stuck, blocked fitting, a spring could still be in the tensioned state. Such a condition is recognized by the measuring and evaluation unit of the coupling according to the invention. There By can be avoided that a dangerous disassembly of the rotary drive is performed by the valve in a spring in the tensioned state. The spring force can now be relaxed first and after renewed determination of the state by the measuring unit safely the drive to be removed from the valve. Further dangerous states can be detected in good time by the continuous measuring device and thus accidents during the maintenance or removal of faults and errors can be avoided.

preferably, If the measuring unit is designed as a torsion measuring unit. Thus, can in radial movement depending on the force and direction of rotation the force curve can be determined.

Of Furthermore, it is preferred that the evaluation unit is a unit to display the measured forces. additionally to the display unit is a recording unit for storing the determined values preferred. Thus, it is possible to read the current state of a valve at any time and to determine. Furthermore, by analyzing the over a certain period of time recorded readings additional important information about the condition of the plant become. Another device for alarming serious Errors or disturbances would also be prefers. Such an alarm could, for example, by Light signals or tone signals are output.

Further it is preferred that the evaluation unit is a rule or control unit for programming or setting parameters and basic values the measuring unit and evaluation, has. This can, for example be preset, which forces should be measured or record over which period and at what intervals the measured values are determined and stored should be given, which forces in normal operation or which states are indicated by an alarm should. Furthermore, it is advantageous for each measured value another Value, e.g. B. time or valve state and assign as so-called Display or save fingerprint. Such a measurement assignment allows a precise error analysis of the plant to a later point in time.

to Measurement of the actuating forces between drive and valve is it is preferred that the measuring unit has at least two strain gauges (DMS). This can be done on the coupling surface Savings for attaching the DMS be provided. There are the strain gauges in a suitable manner to the surface glued to the coupling. The strain gauges are over a connection device, in particular a cable connection, within the measuring unit or connected to the evaluation unit. Preferably the measuring unit has four strain gauges.

at the arrangement of the strain gauges on the coupling surface It is preferred, each two strain gauges on each other opposite sides with respect to the central axis to provide the clutch. The two are on the same page mounted DMS next to each other, parallel to each other and in the longitudinal direction, mounted parallel to the central axis of the coupling. Furthermore, will be the strain gauges by a moisture protection against moisture and moisture protected.

Preferably, the mechanical load, or the force occurring, is detected by a change in resistance of the strain gauge by the inclusion in an electrical circuit and generates a current or voltage signal. In this case, the electrical circuit in the form of a bridge circuit (DMS bridge circuit) z. B. Wheastone bridge, constructed, z. For example, using four strain gages, a full-bridge circuit could be used, and a half-bridge circuit could be used when using two strain gauges. The detected voltage or current signal is preferably fed into an amplifier. The amplifier can be arranged on the coupling. Alternatively, the amplifier can be arranged in a connection box. For this purpose, the connection box has suitable connection terminals for connecting the lines for measuring signal transmission and for connecting the electrical supply lines. In this case, the connection box is preferably arranged on a bridge and connected via a cable connection with the coupling. For the electrical supply of the measuring unit or the bridge circuit, the coupling has a supply connection. In this case, the voltage through a central control system or a local power supply, for. B. a battery can be fed. The corresponding parameters, such. B. zero point, starting point or end point of the measuring unit are at the beginning, ie determined before the start of the measurement in dependence of the electrical supply voltage. The measured values are determined in the electrically connected state without exerting force. Zero point, start and end point are defined in a suitable table. The following table shows an example measuring range as well as the respective assignment of measured values. As voltage or current, with the resulting force. In the following example, the zero point (0 NM) corresponds to a voltage reading of 0.60 mV or a current reading of 12 mA. With a test device, the maximum torque to be measured is specified and so the clutch kali burned and documented in the table. Individually, each coupling can be specified for all measurement requirements. The diameter of the coupling and the material yield point are matched.

Of Furthermore, amplifiers and possible compensation resistors set during the determination of the underlying adjusted.

It is further preferred, several couplings by means of a wired or wireless connection to an external evaluation unit, or central control center, to connect. When using a connection box Each coupling is connected via a junction box to the external one Evaluation unit, or central control center connected. It can the central control center has a computer with suitable software. Thus, one or more clutches can be central to one Point out their functionality to be observed. Possible errors or disturbances in one or more Couplings can thus cost and timely be recognized. Furthermore, such a central control system is used also the control or programming of the individual measuring units.

To the Protection against external influences shows the clutch preferably a protective cover. It is a mobile Protective cover preferred.

By means of a measuring unit which is an integral part of a coupling according to the invention for rotary actuators for actuating force, as well as an evaluation unit which is also part of the clutch or via a connection device provided as an external evaluation unit with the coupling is in communication, transmitted from a drive to a control device actuating forces are measured as well as ausgewer tet. The transmitted torque is determined by measuring a breakaway torque. The measuring method and mode of operation are based on the balance of forces between the drive and the valve when no external force (eg friction) is applied.

preferably, In addition, the occurring depending on the direction of rotation Forces, frictional, pressing and flow forces, measured. These forces are measured as well as the torque in the locked state of the control device, for. B. the valve.

Further It is preferred that the measured values determined with base values, ie. H. the new condition corresponding values are compared. there who determines the currents with the help of a measuring unit and determines from a table the resulting torque.

Farther it is preferred that the underlying assets, the forces in the End positions and the breakaway torques for normal operation (no fault) when first commissioning a control device or after a repair of the control device with built-in clutch be determined. The determined values are in a table registered and saved. The table can be created manually and stored in paper or electronic form. Alternatively, the determination of the underlying assets can also be done by an automated Measurement process performed and electronically stored become. Those determined with a new valve (initial start-up) Underlyings (test results) can also serve as clues when measuring the underlyings after a later repair serve. Avoid the determined values after a repair from the base values after initial commissioning, this is a quality characteristic for the repair carried out. For investigation the base value is in the electrically connected state with the help the measuring unit on the coupling without force, d. H. without air and without spring action, the base condition measured. In this condition is a possibly existing amplifier to a base value, z. B. 12 mA by means of a suitable device, z. B. a programmer. alternative This setting could also be adjusted by possibly existing compensation resistors performed become. The valve is either located to determine the end positions in closed or in open condition. When closed the remaining spring force of the drive acts via the coupling on the seat rings of the fitting. The measured force is in one Table or held in software. To get a faucet in to move a different position, the drive is to redirect. With The help of an ampermeter is the highest when moving the drive Rash to observe and also as a limit in the table or to enter the software. Thus, the highest value applies as the underlying, which is a maximum value for normal powers without harmful effects or errors. Within certain limit values thus becomes the base value for the breakaway torque determined. This measuring process or the determination of the basic values can be repeated several times to make appropriate areas with theirs Define upper or lower limits. It is important that the Differential pressures are measured over the valve.

Of Further, it is preferable that at predetermined intervals and above a predetermined period of time the measurement of the to be transmitted Torque is performed. The can Intervals and the measurement period depending on the application or the situation.

preferably, is exceeded or fallen short of the predetermined Upper or lower limits issued an alarm. Thereby the alarm can z. B. as a light signal or as a sound signal. Farther it is possible that the alarm is in addition with the measured value is displayed and only from a certain number the occurred under or overruns an acoustic or a light signal is output. This will be a counter used with adjustable or programmable limit.

Farther it is preferred that the measured values are stored. there are preferably assigned in addition to the measured values Values recorded and saved. For evaluation of the measured Values, it is therefore advantageous, for. B. the valve state of the solenoid valve with each measured value of the breakaway torque with save. Furthermore, it would be advantageous, the time of the measured value save with.

preferably, can the measuring intervals depending on the measured torque values are varied. For example, could the measuring intervals are extended, if over Constant torque values are determined over a longer period of time were, since in this case the probability for one occurring disturbance decreases. In the case of more frequent or undercutting the given limits would be against a reduction in the measuring intervals appropriate.

The invention will now be described with reference to the drawings by way of particularly preferred embodiment forms exemplified.

It demonstrate:

1 a schematic representation of a coupling according to the invention;

2 a further schematic representation of a coupling according to the invention;

3 a further schematic representation of a coupling according to the invention;

4 a schematic representation showing the arrangement and the connection points of the strain gauges;

5 a block diagram showing the connection diagram of the coupling according to the invention;

6 a representation of the power distribution in the coupling with installed rotary drive to a valve;

7 a further illustration of the power distribution in the coupling with installed rotary drive to a valve;

8th a further illustration of the power distribution in the coupling with installed rotary drive to a valve; and

9 Another illustration of the power distribution in the coupling with installed rotary drive to a valve.

10 a diagram showing the course of the breakaway torque in the initial state and in various possible fault situations; and

11 a perspective view of a coupling according to the invention with connection box.

1 . 2 and 3 show schematic representations of a coupling according to the invention 100 , The coupling according to the invention 100 has a substantially cylindrical shape on which at two opposite positions recesses 16a for attaching the strain gauges 10 . 11 . 12 . 13 are provided. The strain gauges serve this purpose 10 . 11 . 12 . 13 for torsion measurement and thus for measuring the actuating forces between the drive 40 and fitting 41 , By using the strain gauges 10 . 11 . 12 . 13 the shape change, z. B. twist, detected on the surface of the clutch. These are four strain gauges 10 . 11 . 12 . 13 arranged such that in each case two measuring strips next to each other and parallel to each other in the longitudinal direction to the central axis of the coupling 100 in one of the two recesses 16a are mounted on the coupling surface. The two other strain gauges 10 . 11 . 12 . 13 are also arranged in an opposite position next to each other and in the same way in a recess provided on the coupling surface. To merge the strain gauges 10 . 11 . 12 . 13 to a suitable circuit and for connection to the evaluation unit, the strain gauges have connection devices 14 , z. B. a Kabelan circuit on. To protect against moisture, the strain gauges 10 . 11 . 12 . 13 with a moisture protection 15 . 16 covered.

4 shows a schematic representation of the arrangement of the strain gauges 10 . 11 . 12 . 13 and the interconnection to a DMS bridge circuit. The strain gage bridge circuit is made by suitably interconnecting the four strain gauges 10 . 11 . 12 . 13 formed by DMS 10 with DMS 11 as well as DMS 11 with DMS 12 and DMS 12 with DMS 13 and DMS 13 with DMS 10 electrically connected to each other. At the respective connections between two strain gauges thus a total of four connections 17 . 18 . 19 . 20 , Here serve connection 18 and 20 for feeding the supply voltage and the two connections 17 and 19 for reading the measured values.

5 shows a block circuit of a connection diagram of the coupling according to the invention 100 , Measuring unit 200 and the evaluation unit 300 (not shown in the drawing) to supply the supply voltage and to pick up the measured values. The strain gauges 10 . 11 . 12 . 13 are in accordance with the 1 to 4 on the clutch 100 attached and interconnected to a DMS bridge circuit. About the connections 17 . 18 . 19 . 20 is the measuring circuit with a connection box 21 connected. The two on Combinations 17 and 19 are doing over the inputs 24 and 36 the connection box 21 connected and in an amplifier 22 fed. The amplifier provides an output signal of 4-20 mA with a zero point of 12 mA. The two amplifier outputs are via the connectors 25 and 26 the junction box with a divider 27 connected. Thus, the measured values are in the form of differential currents at the two outputs 28 and 29 of the converter 27 available for tap. The supply voltage is connected via the connections 30 and 31 and serves to power the amplifier 22 over the divider 27 as well as for the supply of the measuring unit 200 over the transmitter 32 , The tapped measured values can thus be forwarded to a central control system for further processing, recording and monitoring. In addition, the central control system for supplying the supply voltage via the terminals 30 and 31 serve. For this purpose, a constant supply of an electrical DC voltage between 12 and 24 V is provided by the control system. The supply of several couplings 100 or measuring units 200 via a central control system and the tapping of the measured values of several clutches 100 From a control system is easily feasible with the described arrangement. The measuring sensors of the operated measuring unit are passive and have a resistance accuracy of +/- 0.3 ohms. The application area is designed for temperatures between -12 and + 45 ° C. The circuit described has a very low temperature deviation (0-0.8% of the final value). The hysteresis of the measuring unit is less than 0.2%. Thus, the resulting total error of the measuring unit is less than 1.4% of the final value.

The 6 to 9 show the behavior of the coupling according to the invention 100 with installed rotary drive on a valve 41 , In order to achieve the equality of forces in the operating state, always the friction or resistance forces of the valve on the measurement result influence. 6 shows the initial state with built-coupling 100 with measuring unit 200 the clutch 100 has not been moved yet. The measurement result is 12 mA and corresponds to the zero point. The 7 to 9 show the forces F1 and F2 which occur depending on the direction of rotation. The frictional forces occurring from the pressing forces of the seat rings, the lining, the stuffing boxes and the differential pressures over the valve 41 dependent. The measured values at standstill of the drive 40 show the resistance forces within the valve after the first movement 41 ( 8th and 9 ). The normal state is reached if the measurement result is in the given Li with. Increased deviations from the underlying values indicate changes that could lead to disruptions.

The following is the exemplary behavior of the forces in the valve 41 based on 6 to 9 described:

6 shows the equilibrium of the forces in the initial state: F1 × r1 = F2 × r2.

If the force F1 is generated by a piston and F2 by a spring, then the equilibrium arises, if no foreign force (eg friction) can act. In practice, however, additional forces, FR1 and FR2, occur depending on the direction of rotation. These additional forces are each the sum of frictional, compressive and flow forces. Thus, in the measurement of forces, these additional forces FR1 and FR2 are measured as well as the torque in the locked state of the valve 41 , Compared with the determined basic values, the forces thus provide a quality characteristic for the condition of the valve 41 , Depending on the direction of rotation thus applies F1 × r1 = F2 × r2 + FR2 or in the opposite direction of rotation F2 × r2 = F1 × r1 + FR1.

For example, in the absence of the forces FR1 or FR2, the stuffing box has no friction and the contact forces on the seat rings are not present. This condition indicates, for example, a leaky fitting 41 out. Furthermore, the force due to a broken shaft can not affect the body of the fitting 41 Act. Thus, in the absence or unmeasured forces FR1 and FR2, an error can be deduced. In addition, exceeding the forces FR1 and FR2 indicates an allowable tolerance for an error.

10 shows in a diagram the course of the breakaway torque in various operating states. The position of the solenoid valve is determined by the solenoid valve position 37 parallel to the occurring Forces of the breakaway torque displayed. In this case, a pulse deflection upwards means the switched-on state of the solenoid valve and a pulse deflection back down the switched-off state of the solenoid valve. The course of the solenoid valve position 37 is displayed on the horizontal axis. The vertical axis shows the currents determined by the measuring circuit and the resulting breakaway torque. The basic value for a valve is always determined when new or after a repair. In 10 States A to G show the resulting breakaway torque during initial startup. Any later deviation from the record reflects a change inside and outside the fitting 41 again. As starting position with switched on supply voltage, dissolved drive 40 , within the coupling clearance, without force, the determined measured value gives the so-called zero point with 12 mA. State B shows the initial commissioning under process conditions. This creates the highest breakaway torque. Here are all the forces that are inside the fitting 41 act measured, z. B. stuffing box, forces of the seat rings, differential pressure and other forces. State C shows the normal state. The direction of rotation change is initiated by the solenoid valve position change from OPEN to CLOSE. The change of direction happens over the zero point (12 mA). State D shows the highest breakaway torque in the other direction. Normally, the breakaway torque measured here is less than when driving up, because here the differential pressure is not included. When the valve is open, the differential pressure is not so strong. Condition E shows the condition of the seats and the stuffing box. This only applies if the drive 40 not attached to a stop. In a drive 40 without spring force, the result would be equal to the zero point (12 mA). As a result, the spring force is used as an indicator of a measurement result. With the help of the force of the spring thus the condition of the valve 41 and the forces of the drive 40 checked. An error would z. Example, if despite spring force a result of 12 mA (zero point) would be determined. In such a case, it would be assumed that z. B. the seat rings are no longer tight enough, which has an increased leakage rate or a leaking fitting 41 would result. State F indicates, for example, an increased breakaway torque. A one-time increase would keep the break-away moment within reasonable limits and further observation would be advisable. For longer lasting extension such. B. a renewed increase is to start from an incoming disturbance. However, if the measured values remain within the range of the determined base values, this is an indicator of the good condition of the valve 41 , The measuring range of the measuring device shown goes from 4 mA to 20 mA whereby the mean, 12 mA corresponds to the zero point and 4 mA and 20 mA represent the lower or upper end values of the measuring scale. Predefined ranges in the range of the base values thus show a good state of the control device 41 , Exceeding or falling short of the previously defined range limits indicates a fault or an error. In 10 These range limits are indicated by the markers alpha, betta, gamma and delta. Thus, the desired range for the breakaway torque when the valve position is switched between the marks alpha and delta. When the valve is off, the desired range is between betta and gamma. State J shows, for example, a breakaway torque below the desired limit line delta. State K also shows a smaller breakaway torque. One possible cause could be reduced frictional forces within the valve 41 be. Possible causes for an unreached underlying value in the closed state of the valve could, for. B. are that the spring force is not effective, the seat rings no longer have the necessary sealing and pressing forces, the seats washed out, worn, abraded, the stuffing box no longer has the necessary sealing forces or the spring force by a stop in the drive 40 is canceled. The values determined in the states L and M indicate a blocked valve 41 out. The determined values exceed all other values and are located in the upper or lower limit of the available measuring range. Such a condition indicates, for example, an effective spring force. A required dismantling of the drive 40 can thus be made only after dissolved spring force. The states N and O show, similar to the states J and K, smaller breakaway torques and thus indicate reduced friction forces within the valve 41 out. Larger breakaway torques such. B. in the states H and I, however, indicate increased frictional forces within a closed valve 41 out. Too high or too low torque can, for. B. in addition an alarm can be issued. Furthermore, the values over a certain period of time and with each assigned state of the solenoid valve position 37 recorded or output. The output could be done via a screen, a display, a printer or other output medium. Currently measured values as well as the associated solenoid valve position 37 can also be displayed via an analog or digital display.

11 shows a coupling according to the invention 100 between drive 40 and fitting 41 including a bridge 38 , A connection box 21 is at the bridge 38 fixed and by means of cable connections 39 with the measuring unit 200 on the clutch 100 connected. The connection box 21 includes an amplifier circuit 22 to amplify the measuring signals and terminals 23 . 24 . 25 . 26 . 33 . 34 . 35 . 36 for tapping or forwarding the measured values to a central control station. Alternatively, other functions could also be found in the connection box 21 be arranged. Furthermore, it would be possible to use the amplifier 22 to egg ner ande ren place on the coupling surface or as an intermediate element in the cable connection 39 between coupling 100 and central control center.

100

clutch

10 11, 12, 13

Strain gauges (DMS)

14

connection device for strain gages

15 16

moisture protection

16a

recess

17

measuring connection the strain gauge bridge circuit

18

Power Supply Connector the strain gauge bridge circuit

19

measuring connection the strain gauge bridge circuit

20

Supply voltage connection the strain gauge bridge circuit

21

junction

22

amplifier

23 24, 25, 26

terminals the connection box

27

isolating transformer

28 29

measured value tap on the converter

30 31

supply voltage

32

transmitter

33 34, 35, 36

terminals the connection box

37

Solenoid valve position On off

38

bridge

39

cable connection

40

drive

41

Control means / valve

200

measuring unit

300

evaluation

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 9002877 U1 [0003]

Claims (17)

Clutch ( 100 ) for rotary actuators for transmitting force, wherein the coupling between the drive ( 40 ), in particular a servomotor, and a control device ( 41 ), in particular a valve, flap or rotary control valve, is arranged, characterized in that the coupling ( 100 ) at least one measuring unit ( 200 ) for determining force and at least one evaluation unit ( 300 ) or a connecting device for connecting the measuring unit ( 200 ) to an external evaluation unit ( 300 ) having. Coupling according to claim 1, characterized in that the measuring unit ( 200 ) is designed as a torsion measuring unit. Coupling according to one of claims 1 or 2, characterized in that the measuring unit ( 200 ) is designed as an online measuring unit. Coupling according to one of the preceding claims, characterized in that the evaluation unit ( 300 ) has a recording and / or display unit. Coupling according to one of the preceding claims, characterized in that the evaluation unit ( 300 ) has a control unit for controlling or controlling the measuring unit and / or the evaluation unit. Coupling according to one of the preceding claims, characterized in that the evaluation unit ( 300 ) has a measured value assignment unit. Coupling according to one of the preceding claims, characterized in that the measuring unit ( 200 ) at least two, preferably four strain gauges ( 10 . 11 . 12 . 13 ), wherein the strain gauges ( 10 . 11 . 12 . 13 ) are glued to the coupling surface. Coupling according to claim 7, characterized in that the strain gauges ( 10 . 11 . 12 . 13 ) a connection device ( 14 ), in particular a cable connection. Coupling according to one of claims 7 or 8, characterized in that in each case at least one, preferably two strain gauges ( 10 . 11 . 12 . 13 ) with respect to the central axis of the coupling ( 100 ) are arranged opposite one another on the coupling surfaces. Coupling according to one of claims 7 to 9, characterized in that the strain gauges ( 10 . 11 . 12 . 13 ) a moisture protection ( 15 . 16 ) exhibit. Coupling according to one of claims 7 to 10, characterized in that the strain gauges ( 10 . 11 . 12 . 13 ) are arranged in a bridge circuit or connected to each other. Coupling according to one of the preceding claims, characterized in that the measuring unit has at least one amplifier ( 22 ) having. Coupling according to one of the preceding claims, characterized in that the amplifier ( 22 ) of the measuring unit ( 200 ) in a connection box ( 21 ) is arranged. Coupling according to one of the preceding claims, characterized in that the coupling ( 100 ) has an electrical supply connection. Coupling according to one of the preceding claims, characterized in that at least one coupling ( 100 ) with measuring unit ( 200 ) via a wired or wireless connection with at least one external evaluation unit ( 300 ) connected is. Coupling according to one of the preceding claims, characterized in that the coupling ( 100 ) has a protective cover, in particular a movable protective cover. Use of a coupling according to claims 1 to 16 for fault detection, condition determination, maintenance, accident prevention and / or determination of the quality of the valve and the An drive.