DE19823529A1 - Route determination system - Google Patents

Abstract

The invention relates to a system for determining displacement of a movable measuring object arranged in a system, e.g. a control piston (32) of a valve (10), using a stationary force sensor (41) arranged in the system. Said sensor detects a force resulting from the movement of the measuring object and passing Through a coupling element that can be mechanically deformed and that is arranged between the measuring object and the force sensor. Said coupling element has a determined force-displacement characteristic, for instance an adjusting spring (34) having a defined spring rate. The sensor converts said force into an electrical signal that is proportional to the displacement carried out by the measuring object, for instance the lifting of the control piston (32).

Description

The invention relates generally to a system for Determining the path of a device arranged to be movable in the system Target. Such a system is particularly in the Fluid technology can be found where it comes down to the path of one Measurement object, for example a control piston in one Valve, a piston in a hydraulic cylinder, a ver actuator to determine in a hydraulic pump or the like.

So far, have been used to determine the path of a measurement object Displacement sensors are used to measure the path of the measurement object Record the measurand to be determined and proportion it to the path convert national electrical measurement signal. According to the book "Proportional and servo valve technology", published by from Mannesmann Rexroth GmbH, are used for determination of the stroke of control pistons in proportional and servo valves len mostly used inductive displacement sensors, which the stroke of the Control piston either directly or indi depending on the valve type capture directly and into an electrical proportional to the stroke convert the measuring signal.

With a one-step, directly controlled proportional Directional control valve, for example, the control piston by means of egg stroke-controlled proportional magnet operated directly. A control of the proportional magnet has one for Measured variable of the electrical control signal proportional Stroke of the control piston. By means of an inductive The displacement sensor can be moved via the stroke of the magnetic armature in the Proportio nal magnets indirectly detects the position of the control piston and as an electrical signal for position control to an elec tronic control device are returned. At pre-controlled multi-stage proportional or servo Valves, the control piston is operated hydraulically. In In these cases, the stroke of the control piston is controlled by means of a inductive displacement sensor measured directly.  

To measure the stroke of the armature in the case of a stage directly controlled proportional directional control valve or the stroke of the spool in the case of the pilot operated more stage proportional or servo valves are as before mentioned above, mostly used inductive displacement sensors. In ductive displacement sensors have an AC-excited In production coil system and one to the magnet armature or the Control piston coupled plunger anchor. If the Submersible anchor due to actuation of the magnetic anchor or Control piston is moved relative to the coil system, can arise from the stroke-dependent influencing the inductance of the AC-excited coil system the position of the control piston can be determined.

Likewise, for measuring the stroke of the magnet armature or of the control piston, a displacement sensor with a Hall generator be used in which the magnetic armature or the control piston a control magnet relative to the Hall generator pushes, causing the flux density of the magnetic field, the penetrates the Hall generator, changes. From the on Hall generator tapped Hall voltage, the location of the Control piston are determined.

In addition to the inductive sensor and the Hall generator sensor can also use ohmic Senso with linear potentiometers, galvanomagnetic sensors with field plates as well as analog or digital optoelectronics cal sensors are used for distance measurement. Since that Functional principle of such sensors known to those skilled in the art is on a more detailed explanation of these sensors here in waived.

So that the stroke of a measurement object, up to several Can be 100 mm, but using one of the above listed sensors can be detected, it is required Lich that the sensors are dimensioned at least as large  that they the maximum stroke that the test object and thus the immersing anchor moving in the sensors, control magnet or the like. Can record. This has great Sensor dimensions and thus large dimensions of the whole System in which the sensor is inserted, resulting in what the compactness and the production-related costs of the ge entire system affected.

The object of the invention is therefore to overcome this disadvantage fix by a system to determine the path of an im System movable measuring object is provided, which itself compared to the conventional systems by a low Size distinguishes.

This task is accomplished by a system according to the characteristics of claim 1 solved. Ausgestal invention are subject of the subclaims.

The system according to claim 1 is based on we essential on the principle that to determine the location or the path of a measurement object that can be moved in the system, at for example the path of a control piston of a valve, not the actual path to be determined, son the force that occurs during the movement of the measuring object via a mechanically deformable coupling element on a Force sensor is transmitted. With the help of the detected force can from the known relationship between the on the Coupling element and applied force due deformation of the coupling element, d. H. from the Force-displacement characteristic of the coupling element, which is measured by the measuring object distance traveled can be determined. According to the Erfin Accordingly, manure is not immediately used right size, d. H. the way, as it has been recorded so far, at for example in the sensors described above Lich, but one due to the movement of the target resulting size, d. H. the force that the object to be measured on exerts the force sensor.  

Conventional force sensors can be used as the force sensor be set. Have proven to be particularly advantageous Force sensors proved to be based on the Hall generator principle based.

Since according to the invention, the coupling element by its mechanical deformation takes up the path of the measurement object and conventional force sensors also have a smaller size have as displacement sensors with the invention System compared to conventional systems with displacement sensors a significant reduction in the size of the entire system achieved.

The arranged between the measurement object and the force sensor nete mechanically deformable coupling element stands out advantageously by a linear force-displacement characteristic out. This can be done in a simple manner, for example a spring body working in the Hooke range, such as e.g. B. realize a coil spring. From the linear zu connection between the force that the test object has at its Exercises on the coupling element and by the Force sensor is detected, and from that for the coupling element ment specific linear force-displacement characteristic can be the path of deformation of the coupling element and thus the path of the test object according to Hooke's law. The detected by the force sensor during a movement of the measurement object Force is converted into an electrical Si by the sensor element gnal converted, which at the same time the path of the measurement object pro is portional. The deformation of the coupling element can both by a compressive force and by a train force caused. Depending on how the coupling element ment is connected to the force sensor, can hence either the path of an object under test from an end Position can be moved out and on the coupling element can exert a compressive force or a tensile force, or the Path of a measurement object from a central position  is movable and both a coupling element Can exert compressive force as well as a tensile force become.

Instead of the mechanically deformable coupling element it would also be possible with a linear force-displacement characteristic Lich, a coupling element with a quadra, for example table force-displacement characteristic or the like. To use.

The system according to the invention is particularly in the Fluid technology, d. H. in pneumatics or hydraulics, from Advantage. In this case, the system includes a fluid technical device with a fluid space in which an im general linearly movable measuring object, the force sensor and that is arranged between the force sensor and the measurement object Nete mechanically deformable coupling element arranged are. The force sensor forms the link between the fluid space and a non-fluid space, for example the External environment of the fluid power facility.

The system according to the invention can be part of a tax be chain in which the position of the measurement object in the fluid technical equipment is determined. The fiction system can also be part of a control loop, in which the path of the measurement object in the fluidic one direction determined and returned to a control electronics is carried out to make a target-actual comparison and ge if necessary, the position of the measurement object in the fluidtechni to correct the institution. In this case the path determined by force as an electrical signal to the control device of the fluid power device returned. The principle of the invention is even up Highly sensitive control loops can be used because they are suitable Coordination of the mechanical components of fluidtech African device on each other, the natural frequency range of the mechanical components of the fluid technology equipment  tion can be determined so that the Eigenschwwin does not affect the control accuracy.

Fluid power devices in the sense of the invention summarize all valves, such as. B. Directional control valves, pressure valves le and flow valves, but also control devices such. B. Hydraulic cylinder. With directly controlled proportional Directional valves, for example, the stroke of the control piston about the force that the magnetic armature of the proportional Magnets through the coupling element on the force sensor exercises, be determined. With pilot-controlled proportional Directional control valves can control the stroke of the control piston via the force the of the control piston through the coupling element on the Force sensor exerts, be determined. With one or more stu The servo valves can be used to control the stroke of the control piston about the force of the control piston by the coupling element on the force sensor. With a Hy The dro stroke of the piston in the hydraulic cylinder can be increased the force exerted by the piston through the coupling element exerts the force sensor can be determined.

A force sensor generally consists of an ela mechanically deformable mechanical part that uses the force takes, d. H. a pickup element, and an electrical Part of the force absorbed into an electrical signal converts, d. H. a sensor element. With a view to Fluid pressure-independent conversion of the force absorbed into an electrical signal proportional to the force is from Advantage due to fluid pressure and fluid temperature fluctuation conditions in the fluid space are generally sensitive electrical part of the force sensor, d. H. the sensor element, not exposed to fluid pressure. This can reali Siert that the transducer element and the Sensorele ment are fluid-tightly separated from each other, so that the up slave element in the fluid space and the sensor element in the non fluid space is arranged. With a suitable constructive Design of the transducer element can also be achieved by anyone  that that from fluid pressure and fluid temperature fluctuations influence in the fluid space on the transducer element is minimized.

Fluid power devices often have a spring on that on the measurement object, for example the above mentioned control piston, exerts a compressive or tensile force and thus the position of the test object in the fluid power Establishment determined. This pen is found in the literature mostly referred to as "rule spring". In this case, the Re already present in the fluid power device gel spring the function of the mechanically deformable coupling elements take over, which means no additional coupling element is more required, so that the structure of the entire system and thus the production and manufacturing reduce technical costs.

Of course, even if there is already a rule spring there is an additional force measuring spring for the function of the coupling element. This force measuring spring can for example arranged coaxially within the control spring be. Depending on the spring constant the use The accuracy of the control spring and force measuring spring can be adjusted the force measurement, d. H. the sensitivity of the force sors, in a simple manner to the respective requirements and Adapt application areas.

In the above cases where a spring body forms the coupling element, the spring is supported body, for example the control spring or the force measuring the one, for the sake of simplicity, via a spring plate on the Sensor element of the force sensor. With a system with a fluid power facility in which the location of the DUT is determined by a control spring, can be found in Ab dependence on the design of the spring plate the part of the force sensor located in the fluid space and the Transducer element axially following the control spring or  be arranged coaxially within the control spring. By the latter arrangement can reduce the overall size of the system be reduced even more.

Another advantageous embodiment of the invention modern system results when the transducer element of the Force sensor has a centrally arranged cone section, d. H. a tapered depression or a tapered front jump, and the spring plate one to the cone section of the Transducer element adapted cone section, d. H. a ke yellowing projection or a tapered recess. Because the force attack on the transducer element in this case This cone section can be used to measure the force largely free of lateral forces occurring in the fluid space or obliquely acting forces.

The sensor element of the force sensor is simple for the sake of membrane-like design. In this case, ne largely independent of the fluid pressure measurement of the force are constructive measures on the membranarti gene transducer element and / or provided on the force sensor, a fluid pressure equalization between the two sides enable the membrane-like transducer. For example can the membrane-like pickup element one or more Have fluid openings through which the fluid at a Movement of the measurement object from one side to the other te of the membrane-like sensor element can flow, so that the same fluid pressure is present on both sides. As well A fluid channel can be formed in the force sensor a fluid connection between the sides in front behind the creates membrane-like pickup element, so that thereby Fluid pressure compensation is possible. In addition to the constructive Measure that allows fluid pressure compensation the transducer element must also be designed so that it is only responds above a certain force, d. H. that it is from a weak change in fluid pressure in the fluid space largely unbe remains influenced.  

In principle, any sensor can be used as a force sensor be on an ohmic, inductive, optoelectronic or galvanomagnetic measuring principle based. Im he system according to the invention is preferably a force sensor ver turns the one actuated by the pickup element Control magnets and a Hall generator. In this In this case, the membrane-like sensor element deforms under the influence of those transmitted via the coupling element Force and shifts the ver with the transducer element binding control magnets relative to the Hall generator, which changes the flux density of the magnetic field that surrounds the Hall generator interspersed, changes. The on the Hall generator tapped Hall voltage is the absorbed force per portionally. From the measured force, which as the electri cal signal is output, can be via the known Force-deformation path relationship of the coupling element Determine the stroke of the measurement object.

Further features and advantages of the Sy according to the invention stems follow from the description below of a be preferred embodiment, with reference to the attached Drawing is referenced. It shows

Figure 1 shows an embodiment of the system according to the invention with a 4/3-way proportional directional valve and egg NEM force sensor.

Fig. 2 is a sectional view of the force sensor;

FIG. 2a is a schematic representation of a Hall generator;

Fig. 3 shows a modification of the system shown in Fig. 1; and

Fig. 4 shows a further modification of the system shown in Fig. 1 Darge.

In the following the system according to the invention is used for loading adjustment of the path of a measurement object on an execution example game described. In this embodiment, this System a pilot operated 4/3-way proportional directional valve and one based on the Hall generator principle Force sensor on. However, it will explicitly depend on it indicated that the system according to the invention is not based on this Embodiment is limited, but generally in the Cases apply where it is basically possible and is expedient, the path of a measurement object by means of a To determine the force sensor.

First of all, the structure and operation of the 4/3-way proportional directional valve is explained. The 4/3 proportional directional control valve shown schematically in FIG. 1 consists of a pilot valve 10 and a main valve 30 which can be actuated by the pilot valve 10 .

The pilot valve 10 serves to control the main valve 30 and has a pilot valve housing 11 , two proportional magnets 12 and 13 attached to the pilot valve housing, two pilot pistons 14 and 15 and two compression springs 16 and 17 . The proportional magnet 12 serves to actuate the pilot piston 14, which is axially displaceable in a housing recess of the pilot valve housing 11, against the spring force of the compression spring 16 . The proportional magnet 13 serves to actuate the axially displaceably arranged pilot piston 15 in egg ner further housing recess of the pilot valve housing 11 against the spring force of the compression spring 17th Fluid channels 18 , 19 , 20 and 21 are formed in the pilot valve housing 11 , as shown in FIG. 1. In the pilot piston 14 , a fluid channel 22 is formed which, depending on the position of the control piston 14, connects the fluid channel 20 either to the fluid channel 18 or to the fluid channel 19 . In the pilot piston 15 is formed a fluid passage 23, the fluid passage 21 either with the pressure fluid passage 18 or with the fluid channel 19 ver binds depending on the position of the pilot piston 15 °.

The main valve 30 has an axially displaceably arranged main control piston 32 in a housing recess of a main valve housing 31 , a control spring 34 arranged in a spring chamber 33 on an end face of the main control piston 32 , which the main control piston 32 with a compressive force acting to the right in FIG. 1 acted upon and has a certain spring constant, a arranged in a white direct spring chamber 35 on the other end face of the main control piston 32 control spring 36 , which acts on the main control piston 32 with a pressure force acting in FIG. 1 to the left and has a certain spring constant, and a formed at the left end of FIG. 1 of the main valve housing 31 bore 31 a with internal thread, which is in communication with the spring chamber 33 . As will be described below, a force sensor 41 is screwed into this bore 31 a from the outside, on which the control spring 34 is supported. The spring constants of the two control springs 34 and 36 are of the same size. The Hauptsteuerkol ben 32 is accordingly, provided that neither of the two proportional magnets is supplied with direct current, by the two control springs 34 and 36 in a central position. In the main valve housing 31 are also a pump connection P, a with the pump connection P and the fluid channel 18 of the pilot valve 10 communicating fluid channel 37 , two tank connections T ₁ and T ₂ , one with these tank connections T ₁ and T ₂ and the fluid channel 19 of the pilot valve 10 in connection fluid channel 38 , two consumer ports A and B, which depending on the position of the main control piston with the pump port P or one of the two tank ports T ₁ and T _{2 can be} connected, a fluid channel 39 , the fluid channel 20 of the pilot valve 10 connects to the spring chamber 33 , and a fluid channel 40 , which connects the fluid channel 21 of the pilot valve 10 to the spring chamber 35 , is formed.

The spring chamber 33 forms a fluid chamber in the system according to the invention.

In the rest position, ie in the state without power supply to the proportional magnets 12 and 13 , the control pistons 14 and 15 are in the position shown in FIG. 1. The spring spaces 34 and 35 are relieved since the fluid supply from the pump connection P to the spring spaces 33 and 35 is interrupted and the fluid from the spring spaces 33 and 35 via the fluid channels 39 , 20 , 22 , 19 and 38 or via the fluid channels 40 , 21 , 23 , 19 and 38 and the tank connections T ₁ and T ₂ can flow back into the tank. Since in this state only the compressive forces of the control springs 34 and 36 act on the end faces of the main control piston 32 which are of the same size, the main control piston 32 remains in the central position shown in FIG. 1.

If the proportional magnet 13 on the right in accordance with FIG. 1 is driven with a direct current, a guide rod connected to the magnet armature pushes the pilot piston 15 to the left. The fluid flowing through the pump connection P into the fluid channel 37 then passes via the fluid channels 18 , 23 , 21 and 40 into the right spring space 35 according to FIG. 1, whereby the main control piston 32 is shifted to the left. The main control piston 32 is moved out of the middle position shown in FIG. 1 until the fluid pressure in the spring chamber 35 according to FIG. 1 on the right front side of the main control piston 32 and that according to FIG. 1 on the left front side of the main control piston 32 acting Fe derkraft the control spring 34 are in equilibrium. The fluid pressure in the spring chamber 34 is proportional to the direct current fed into the proportional magnet and the magnetic force generated thereby. The main control piston 32 is moved by a path proportional to these quantities, which in turn generates a fluid volume flow proportional to these quantities at the consumer connection A.

A control of the left proportional magnet 12 according to FIG. 1 results accordingly in a direct current and the magnetic force generated thereby displacement of the main control piston 32 according to FIG. 1 to the right, whereby at the consumer connection B a fluid volume proportional to these quantities menstrom is generated.

The reference numeral 41 denotes a force sensor which, as already mentioned above, is screwed fluid-tight into the bore 31 a of the main control valve housing 31 . As shown in Fig. 1, the control spring 34 is supported by a spring plate 50 on the sensor element 42 of the force sensor 41 . The force sensor 41 , the spring plate 50 and the control spring 34 are arranged one after the other in this order.

According to the schematic illustration in Fig. 2 41 consists of the force sensor consisting essentially of a housing 44 right on the FIG. 2 end side of the control spring 34 coaxial housing recess 45 and left in the FIG. 2 end side an also to the control spring 34 has coaxial housing recess 48 , the Aufnehmerele element 42 , a bolt 46 which extends away from the transducer element 42 into the housing recess 45 and carries a control magnet 47 at its free-standing end, and the Hall generator 43 fastened in the housing recess 48 .

The housing cutout 45 and the housing cutout 48 are designed to be separate from one another in a fluid-tight manner, as shown in FIG. 2. As is further shown in Fig. 2, the sensor element 42 is membrane-like over the Ge housing recess 45 attached to the housing 44 . The housing recess 45 is dimensioned at least so large that the control magnet 47 can move freely in a pressure-induced stress of the takeup element 42 in axial displacement of the housing recess 45th

The Hall generator 43 is, as is shown schematically in Fig. 2a, made of a substantially rectangular gene thin semiconductor chip 70 and generates a Hall voltage U _H from a control current I and a control field I right through magnetic field B. . Is at two opposite longitudinal sides 71, 72 of the semi-conductor wafer is applied a voltage, I 72 of the semiconductor chip 70 flows the so-called control current between the two longitudinal sides 71. The magnetic field B produced by the control magnet 47 passes through the Hall generator 43 perpendicular to the control current I flowing between the two long sides 71 , 72 of the semiconductor die 70 , as a result of which the charge carriers, due to the Lorenz force, move to one of the opposite sides 73, 74 of the half lead platelets 70 are pushed. The so-called Hall voltage U _H can thereby be tapped on the two other longitudinal sides 73 , 74 of the semiconductor die 70 . This increases with the strength of the control current I and the magnetic flux density B.

If now the FIG. 1 right proportional solenoid supplied with a direct current, the Hauptsteuerkol is ben 32 according to Fig. Shifted 1 to the left, whereby the Re gel pen to a motion amount corresponding to the force exerted by the main control piston 32 to the control spring 34 force 34 is proportional, is compressed. At the same time, the control magnet 47 is pushed as a result of a pressure loading of the sensor element 42 caused by force transmission toward the Hall generator, as a result of which the magnetic flux density through the Hall generator 43 increases. The resulting tapped on the Hall generator 43 is ascended Hall voltage U _H which functions as an electrical signal in the inventive system is propor tional to the force pick-up taken on the 42nd

The force sensor 41 accordingly detects the force exerted by the main control piston 32 , which functions as a measurement object, via the control spring 34 , which functions as a mechanically deformable coupling element and has a specific force-displacement characteristic. From this force and from the known linear force-displacement characteristic of the control spring, the deformation travel of the control spring 34 can be determined according to Hooke's law "F = cs", "c" being the spring constant of the control spring 34 and "s" Deformation path of the control spring 34 is. The deformation of the control spring 34 is also the path that the main control piston travels in its movement 32nd

In order to enable a largely fluid pressure-independent measurement of the force, fluid openings 49 are formed in the sensor element, through which the fluid in the fluid space can flow from the right-hand side of the membrane-like sensor element in FIG. 2 to the left side, so that on both sides of the membrane the same fluid pressure is present.

As can be seen in Fig. 2, the Aufneh merelement 42 of the force sensor 41 has a centrally arranged conical projection 51 and the spring plate 50 has a conical projection 51 of the transducer element 42 is fitted with a conical recess 52 . As a result of the force applied to the sensor element 42 via these cone sections 51 , 52 , a force measurement is achieved which remains largely unaffected by lateral forces or obliquely acting forces occurring in the fluid space.

Fig. 3 shows a modification of the above-described NEN system for determining the path of the main spool 32 of the 4/3-way proportional directional control valve. As shown in Figure 2, the force sensor 41, the spring plate 50 and the control spring FIG. 1 and FIG. 34 are arranged in this order one behind the other, in this modification, the space in the fluid portion located of the force sensor 41 and the Federtel are ler 50, on which the Control spring 34 supports, partially arranged within the control spring 34 , which reduces the overall length of the entire system.

Fig. 4 shows a further modification of the system according to the invention for determining the path of the main control piston 32 . As is 4 shown in Fig., Is within the control spring 34, which acts on the main control piston 32 with a pressing force in Fig. 4 to the right, a force measuring spring 60 is arranged, which in this case assumes the function of mechanically deformable coupling member and the is supported via the spring plate 50 on the sensor element 42 of the force sensor 41 . Depending on the spring constant of the control spring and force measuring spring used, the accuracy of the force measurement, ie the sensitivity of the force sensor, can be adapted to the respective requirements and areas of application.

In the system described above, the force sensor can only determine the stroke of the main control piston 32 which is caused as a result of actuation of the proportional magnet 13 . In order to determine the stroke of the main control piston 32 caused by actuation of the proportional magnet 12 , a second force sensor can be used, which is arranged opposite the force sensor 41 on the other side of the main control piston 32 and detects the pressure force transmitted via the regulating spring 36 . Alternatively, it would also be possible to connect the control spring 34 to the main control piston 32 and the sensor element 42 of the force sensor 41 in such a way that the control spring can exert both a compressive and a tensile force on the sensor element 42 , so that the force sensor 41 can detect a pressure as well as a tensile force. Even without such a connection of the control spring 34 to the main control piston 32 and the transducer element 42 of the force sensor 41 , in the system described above with the 4/3-way proportional valve, basically a single force sensor is sufficient to activate one or the other elec tromagneten to measure the path of the main control piston 32 . Both control springs 34 and 36 must then be preloaded in the neutral position of the main control piston 32 shown. Then namely when the main control piston 32 is shifted from the neutral position shown in one direction, the control spring 34 is tensioned more and is relaxed more when shifting in the other direction. The force sensor 41 then senses a change in force.

Claims (17)

1. System for determining the path of a measurement object ( 32 ) movably arranged in the system by means of a force sensor ( 41 ) arranged stationary in the system, which via a mechanically deformable coupling element ( 34 ,) arranged between the measurement object ( 32 ) and the force sensor ( 41 ). 60 ), which has a certain force-displacement characteristic, detects a force caused by movement of the measurement object ( 32 ) and converts it into an electrical signal which is proportional to the distance traveled by the measurement object ( 32 ). 2. System according to claim 1, characterized in that the coupling element ( 34 , 60 ) is a coupling element with egg ner linear force-displacement characteristic, in particular an elastic spring body. 3. System according to claim 1 or 2, characterized in that the system has a fluidic device ( 10 , 30 ) with a fluid space ( 33 ) in which the measuring object ( 32 ) is arranged to be linearly movable, and that the force sensor ( 41 ) separates the fluid space ( 33 ) from a non-fluid space ( 48 ). 4. System according to claim 3, characterized in that the system has control electronics for controlling the fluid power device ( 10 , 30 ), and that the fluid power device ( 10 , 30 ), the force sensor ( 41 ) and the control electronics form a re gelkreis . 5. System according to claim 3 or 4, characterized in that the force sensor ( 41 ) has an elastically deformable sensor element ( 42 ) for absorbing the force and a fluid-tight relative to the sensor element ( 42 ) separated sensor element ( 43 ) for converting the force into that has an electrical signal, wherein the pickup element ( 42 ) in the fluid space ( 33 ) and the sensor element ( 43 ) is arranged in the non-fluid space ( 48 ). 6. System according to claim 5, characterized in that the coupling element ( 34 , 60 ) is a test object ( 32 ) axially with a force acting control spring ( 34 ), the force sensor ( 41 ) on one of the test object ( 32 ) via the Control spring ( 34 ) responsive to the transducer element ( 42 ) transmitted pressure and / or tensile force. 7. System according to claim 6, characterized in that the control spring ( 34 ) is supported via a spring plate ( 50 ) on the sensor element ( 42 ) of the force sensor ( 41 ). 8. System according to claim 5, characterized in that the coupling element ( 34 , 60 ) is a force measuring spring ( 60 ) which is arranged within a control object ( 34 ) axially acting with a force on the measurement object ( 32 ), the force sensor ( 41 ) responds to a pressure and / or tensile force transmitted from the measurement object ( 32 ) via the force measuring spring ( 60 ) to the transducer element ( 42 ). 9. System according to claim 8, characterized in that the force measuring spring ( 60 ) is supported via a spring plate ( 50 ) on the sensor element ( 42 ) of the force sensor ( 41 ). 10. System according to any one of claims 6 to 9, characterized in that the part of the force sensor ( 41 ) located in the fluid space ( 33 ) and the sensor element ( 42 ) are at least partially arranged coaxially within the rule spring ( 34 ). 11. System according to any one of claims 6 to 9, characterized in that the part of the force sensor ( 41 ) and the sensor element ( 42 ) located in the fluid space ( 33 ) are axially net following the control spring ( 34 ). 12. System according to any one of claims 7 to 11, characterized in that the sensor element ( 42 ) has a rounded ge conical section ( 51 ) on which the Fe derteller ( 50 ) sits. 13. System according to any one of claims 5 to 12, characterized in that the transducer element ( 42 ) is membrane-shaped and enables fluid pressure compensation between the two diaphragm sides. 14. System according to any one of claims 1 to 13, characterized in that the force sensor ( 41 ) is an ohmic, inductive, optoelectronic or galvanomagnetic force sensor. 15. System according to claim 13, characterized in that the force sensor ( 41 ) has a through the pickup element ( 42 ) movable control magnet ( 47 ) and one with respect to the control magnet ( 47 ) stationary Hallge generator ( 43 ). 16. System according to claim 8, characterized in that the force measuring spring ( 60 ) has a lower spring constant than the control spring ( 34 ). 17. System according to claim 3, characterized in that the fluidic device ( 10 , 20 ) is a valve, the test object ( 32 ) a control piston and the coupling element ( 34 , 60 ) is a control spring determining the axial position of the control piston in the valve.