CN115638917A

CN115638917A - Pressure measurement device, measurement method, and computer program product

Info

Publication number: CN115638917A
Application number: CN202210878468.5A
Authority: CN
Inventors: W·瓦妮莎·伊莎贝尔
Original assignee: Siemens Sensors and Communication Ltd
Current assignee: Siemens Sensors and Communication Ltd
Priority date: 2021-07-26
Filing date: 2022-07-25
Publication date: 2023-01-24
Also published as: DE102021208006A1

Abstract

The invention relates to a pressure measuring device (10) comprising several housings (12) which each partially enclose a tube (11) containing a fluid. The shells (12) are connected to each other by a stretchable connecting member (14). According to the invention, at least one of the stretchable connecting members (14) has a grating (30) which is designed to produce a diffraction pattern (39) which is variable under a tensile load (31). The invention also relates to a method (100) for measuring a pressure (28) in a pipe (11) filled with a fluid using the claimed pressure measuring device (10) and to a pressure measuring system (50) comprising such a pressure measuring device (10). The invention further relates to a computer program product (80) by means of which the operating behavior of such a pressure measuring device (10) can be simulated.

Description

Pressure measurement device, measurement method, and computer program product

Technical Field

The invention relates to a pressure measuring device for non-invasive pressure measurement of a fluid in a pipe and to a measuring method suitable therefor. The invention also relates to a corresponding pressure measurement system and a computer program product for simulating an operating behavior of a corresponding pressure measurement device.

Background

Publication WO 2021/071859 A1 discloses a pressure sensor for non-invasive measurement of static and dynamic pressure components in a pipe. The strain sensor has a wire of polyvinylidene fluoride wound around the tube to measure a variable dynamic pressure component. In addition, the pressure sensor has a strain gauge for measuring the static pressure component. The strain gage is also wound around the tube.

Patent application US 2005/0072216 A1 discloses a piezoelectric sensor for measuring variable pressures in a pipe. The piezoelectric sensor comprises a cable wound around a tube such that expansion of the tube caused by a rise in pressure is detected as longitudinal stretching of the cable.

Disclosure of Invention

Pressure measuring devices for non-invasive pressure measurement are increasingly used in various applications, such as automation systems. It is desirable to be able to manufacture a space-saving pressure measuring device at low cost. There is also a need to improve measurement accuracy and durability to be reliably used in adverse environmental conditions. It is an object of the present invention to provide a pressure measurement device which is improved in at least one of the aspects described.

The above object is achieved by a pressure measuring device according to the invention, by means of which the pressure in a pipe filled with a fluid can be measured. The tube may have any closed cross-section and may, for example, be at least partially filled with a liquid, a gas or a mixture thereof. The fluid located in the tubular may exert static and/or dynamic pressure on the tubular walls. The pressure measuring device comprises several housings, which are each designed to partially enclose a pipe containing a fluid, i.e. to partially enclose a pipe containing a fluid. For this purpose, the shape of the housing substantially corresponds to the outer contour of the tube and in the assembled state at least partially bears against the outer contour of the tube. The shells are interconnected by connecting members adapted to absorb tensile loads. The expansion of the pipe due to the pressure rise is transmitted by the housing as a tensile load into the connecting member. According to the invention, at least one of the stretchable link members has a grating adapted to produce a variable diffraction pattern. The diffraction pattern is variable under the influence of a tensile load present in the connecting member. For this purpose, the grating is connected to or integrated in the connecting element, so that the grating likewise undergoes at least one tension caused by the tensile load. Thus, a pressure rise or a pressure drop in the fluid-filled tube may cause a change in the diffraction pattern at the at least one stretchable connecting member. The change in the diffraction pattern can be detected accurately in a simple manner, so that the pressure in the fluid-filled pipe can be determined accurately. The pressure measuring device according to the invention is designed for non-invasive pressure measurement in a pipe containing a fluid. The measurement principle achieved thereby is mechanical and optical and thus has a high resistance to electrical interference. The pressure measuring device according to the invention can therefore be used advantageously in complex automation systems in which considerable interfering electromagnetic fields are present due to the multiplicity of existing devices. Furthermore, such a grating can be formed compactly, for example in the form of slits, notches, circular holes, rectangular voids or other polygonal voids. The pressure measuring device according to the invention can therefore be produced overall in a space-saving manner.

In one embodiment of the claimed pressure measurement device, the tensile load exerted on the at least one connection member during pressure measurement is oriented substantially tangential to the pipe. Such an orientation may ensure that the expansion (i.e. radial enlargement) of the pipe elements is fully translated into a load on the respective connection members. In particular, a bending component in the deformation of the at least one connecting member is suppressed. In this way, a substantially uniaxial loading condition is generated in the at least one connection member, which ensures an improved measurement accuracy.

Furthermore, a variable diffraction pattern can be produced by illuminating the grating in the radial direction of the tube. Wherein the irradiation can be carried out by means of visible light, ultraviolet radiation and/or infrared radiation. For this purpose, the pressure measuring device can be equipped with a light source, which is fastened to the pressure measuring device. The light source is designed to cooperate with the grating to produce a measurable, i.e. technically useful, variable diffraction pattern. For this purpose, the light source can be designed, for example, to emit monochromatic radiation. Thus, different light sources whose radiation is not influenced by electromagnetic fields can be used, depending on the existing installation space on the respective tube. By irradiating in the radial direction, the variation of the variable diffraction pattern can be easily recognized. Such irradiation may be continuous or temporary. Even if the irradiation is continued, no adverse effect is caused on the pipe or the fluid in the pipe. Thus, there is no need to consider any adverse effects when designing the claimed pressure measurement device, which makes design and manufacturing simple and cost-effective. While the temporary illumination can reduce the energy requirements for operation of the pressure measurement device. This in turn makes it possible for the claimed pressure measuring device to operate for a long time by means of an energy storage device (for example a battery). In particular, it is advantageously possible to design the pressure measuring device as a wireless device which transmits the measurement data via a radio connection. This effect can be further increased if the light source is designed, for example, as an LED.

In a further embodiment of the claimed pressure measuring device, the grating has at least one recess, which is designed to produce a variable diffraction pattern in dependence on the direction. In this case, the variation in the diffraction pattern in the circumferential direction can be distinguished from the variation in the diffraction pattern in the axial direction with respect to the pipe. For this purpose, the at least one recess can be designed, for example, as a diffraction slot oriented in the circumferential or tangential direction of the tube or as a diffraction slot oriented in the axial direction. Alternatively or additionally, the at least one recess may also be polygonal, in particular rectangular or square. The grating may also have several voids of the above-mentioned type or a combination thereof. This allows, for example, the diffraction pattern changes caused by changes in the temperature of the tubing to be distinguished from those caused by changes in pressure. In this way, the claimed pressure measurement device will be easily adapted to perform temperature compensated pressure measurements. Furthermore, the tube can be designed as a thin-walled tube. In the case of thin-walled tubes, it can be taken into account that, when subjected to pressure loads, they stretch twice in the circumferential direction than in the longitudinal direction. By thin-walled tube is meant a tube having an outer diameter to inner diameter ratio of less than 1.2.

Furthermore, the claimed pressure measuring device can be provided with a detection means in one region of the grating, which detection means is designed to detect a variable diffraction pattern. The detection member may be arranged such that at least one connection member having a grating is located between the light source and the detection member. For this purpose, the at least one connecting element with the light barrier can be designed, for example, as a sheet or strip, so that sufficient space can also be provided between the connecting element and the tube for mounting the detection element or the light source. In the case of a correct installation, the expansion of the tube will be substantially completely converted into a tensile load on the connecting member. The claimed pressure measuring device is therefore particularly easy to assemble overall, so that an accurate measuring operation can be reliably achieved.

The detection means can be designed, for example, as an array, in particular a photodiode array or a photoresistor array. The array or grid-like layout allows at least a two-dimensional resolution image of the variable diffraction pattern to be detected with a low hardware effort. Furthermore, the photoresistors are virtually unaffected by aging phenomena and are therefore particularly suitable for continuous operation. Alternatively or additionally, the detection means can also be designed as an image sensor, for example a CMOS sensor or a CCD sensor. Such image sensors are particularly compact and provide higher resolution, so that changes in the diffraction pattern can be detected more accurately. The claimed pressure measuring device can thus be realized with cost-effective components and with greater precision and compactness. In this way, the claimed pressure measuring device can also be used on pipes which have only a small installation space around them. Therefore, the claimed pressure measurement device has a wide range of applications.

Furthermore, the claimed pressure measurement device may be designed to be non-destructively detachable from the tubular. For this purpose, for example, at least one connecting element can be connected, in particular screwed, to one of the housings in a non-destructive, detachable manner. In particular, a non-destructive separation of the pressure measuring device from the pipe can be ensured by the fact that there is no material-bonded connection (e.g. adhesive or welded connection) between the two. Thus, the claimed pressure measurement device can be easily mounted on a pipe having any kind of surface. In particular, it is not necessary to use a measuring tube whose surface has been specially treated (i.e. machined). In this way, the claimed pressure measurement device can be installed in existing equipment in a cost-effective manner during retrofitting. Furthermore, the housing may be designed to be mounted on the pipe independently of pipe tolerances. The housings may each have at least one clamping block that is adjustable from the outside. This allows the installation of the pressure measuring device to be adjusted, for example, in order to be able to set a desired pretensioning force in the at least one stretchable connecting element.

In a further embodiment of the claimed pressure measuring device, the pressure measuring device has at least two tensile connecting elements, each of which has a light barrier. Variable diffraction patterns can be detected on each of these gratings. By individually evaluating these variable diffraction patterns, different deformations in the individual stretchable connecting member regions can be recognized. This allows, for example, to identify a bend in the fluid-filled pipe, which is then distinguished from a change in pressure of the fluid. The claimed pressure measuring device is therefore very resistant to undesired influences and has a wide range of possible uses.

The aforementioned object is also achieved by a method according to the invention for measuring the pressure in a pipe containing a fluid. The method comprises a first step of providing a pipe containing a fluid, the pressure of which (i.e. the pressure inside the pipe in the form of static and dynamic pressure) needs to be measured. In a first step, the tube containing the fluid is also provided with a pressure measuring device to be used for measuring the pressure. For this purpose, the pressure measuring device is mounted on a pipe which contains the fluid. The pressure measuring device comprises several housings which are interconnected by stretchable connecting members. The stretchable connecting member may be pre-tensioned in the assembled state. In the assembled state, expansion of the tube due to pressure changes inside the tube translates into an increase in the tensile load experienced by the tensile connecting member. The method further comprises a second step of illuminating the at least one stretchable link member with a light source. The at least one stretchable connecting member comprises a grating which is illuminated by the light source in the second step. The diffraction pattern is generated by illuminating the grating.

The method according to the invention furthermore comprises a third step of detecting the current diffraction pattern generated in the second step. In a third step, the detected diffraction pattern is further compared with a reference diffraction pattern and the difference between the two is determined. The reference diffraction pattern may be, for example, a diffraction pattern generated at a known ambient temperature, a known temperature of the fluid in the pipe, and a known ambient pressure after the pipe pressure has been calibrated. The method further comprises a fourth step of determining the pressure present in the fluid-filled pipe, which may include static pressure and dynamic pressure, based on the difference determined in the third step. That is, the difference measured in the third step is a measure of the pressure present in the pipe containing the fluid. To this end, the difference can be evaluated by a table of values, an algorithm or artificial intelligence (e.g., a neural network), ultimately resulting in the current pressure in the tubular. The method according to the invention is essentially optical-based, so that the electromagnetic influence (e.g. a magnetic or electric field) has no disturbing effect on the diffraction pattern generated at the at least one connection member. Furthermore, the diffraction pattern is continuously variable, and therefore the measurement accuracy that can be achieved is limited substantially only by the accuracy that can be achieved when detecting a variable diffraction pattern. Even a simple detection means, such as a photodiode array, a CMOS sensor or a CCD sensor, can provide a higher accuracy for this purpose. The method according to the invention is suitable for further increasing the measurement accuracy achievable in pressure measurement by adding future higher resolution CMOS sensors, CCD sensors or similar functional components. The method according to the invention can therefore also be used to rapidly exploit the future technical potential of the respective detection means.

In one embodiment of the claimed method, the grating may be oriented substantially tangential to the tubular. For this purpose, the grating can be fixedly connected to at least one stretchable connecting member. In this way, the load present in the at least one tensile linking member may be substantially fully converted into deformation of the grating. In case the grating is oriented tangentially to the tube, a higher measurement accuracy will be obtained overall.

Furthermore, in the claimed method, the deformation of the grating in the circumferential direction can be determined in a third step. Alternatively or additionally, the deformation of the grating in the axial direction can be determined. To this end, the grating may be designed to exhibit distinguishable circumferential and axial variations. The pressure measuring device can in particular be provided with a detection means which can be used to detect two-dimensional changes in the diffraction pattern. The cause of axial stretching of the tube is usually thermal expansion, i.e. a temperature rise. At the same time, this thermal expansion also causes radial expansion of the pipe elements. This causes a change in the diffraction pattern at the grating, similar to the effect of a pressure rise in the tube. The effect of the pressure rise on the pipe in the axial direction is negligible. By comprehensively measuring the deformation of the grating in the circumferential direction and the axial direction, the temperature compensation can be carried out on the pipe fitting. The fluid temperature can also be determined from information such as the outside diameter, wall thickness, material specifications of the pipe, and/or ambient temperature.

Furthermore, in the claimed method, the total intensity of the diffraction pattern, the width of the central maximum, the number of secondary maxima, the circumferential position of the secondary maxima, the number of secondary minima and/or the circumferential position of the secondary minima can be detected in a third step. Based on these variables, the deformation of the stretchable connecting member in the circumferential direction of the tube can be detected in a simple manner. When detecting the number of secondary maxima or secondary minima, those secondary maxima or secondary minima which are adjacent to one another in the circumferential direction are detected. This is a variable of the diffraction pattern which can be determined accurately in a simple manner. Combining at least two of these variables also makes it possible to cross-check the plausibility of the expansion of the pipe, which is derived from the individual variables. Whereby damage to the at least one tensile link member may be identified, but is not limited thereto. So-called damage may include plastic deformation, such as occurs due to relaxation. In the measurement of the expansion of the tube and thus the pressure in the fluid, it is possible to deliberately ignore variables on the diffraction pattern which no longer have sufficient force to interpret them. Thus, the claimed method is very resistant to deterioration of the stretchable connecting member. As a result, the pressure measuring device used for the method has a technically longer service life.

The aforementioned object is also achieved by a pressure measuring system according to the invention, which is designed for measuring a pressure in a pipe with a fluid contained therein. The pressure measurement system includes a pressure measurement device connectable to a light source. The light source is used to measure the pressure in a predetermined operation of the pressure measuring device. The pressure measuring device is coupled to the evaluation unit in order to be able to forward the measurement signal generated by the pressure measuring device to the evaluation unit. The measurement signal may be generated directly by the detection means of the pressure measurement device or may have been at least partially processed. The evaluation unit is designed and adapted to evaluate the measurement signal in order to determine on the basis thereof the pressure prevailing in the fluid-filled pipe. For this purpose, the pressure measuring device can be designed according to one of the embodiments described above. As an alternative or in addition, the evaluation unit can be designed to carry out at least one embodiment of the above-described method. For this purpose, the evaluation unit can be provided with a correspondingly designed control program product, with a corresponding chip, or with a combination of both. The pressure measuring system according to the invention makes it possible to achieve the technical advantages of the above-described pressure measuring device and/or the method to a certain extent. The pressure measuring system according to the invention can be arranged in a simple manner in an existing application, such as an automation system, during a retrofitting process.

The object set forth at the outset is also achieved by a computer program product according to the invention, which is designed to simulate the operating behavior of a pressure measuring device arranged on a pipe which contains a fluid. The pressure measuring device is arranged to measure the pressure present in the pipe containing the fluid. The pressure measuring device to be simulated in terms of operational behavior is designed according to one of the above-described embodiments. The operational behavior of the pressure measuring device includes the radial expansion of the tubular member containing the fluid as its internal pressure rises and the force exerted by the tubular member on the pressure measuring device. Also, the expansion of the tubular that occurs when the ambient temperature of the tubular rises or the temperature of the fluid within the pipe rises can be attributed to the operational behavior of the tubular. Furthermore, the elastic deformation behavior of the stretchable connecting member may pertain to an operation behavior induced by a force exerted by the tube. The elastic deformation behavior of the tensile connecting member again leads to a change of the grating at the tensile connecting member, which may also be attributed to the operating behavior of the pressure measuring device. Further, the operational behavior may also include changes in the diffraction pattern due to changes in the diffraction pattern. The detection behavior of the detection member and the measurement signal of the detection member may also pertain to the operating behavior of the pressure measuring device.

The computer program product may further have a data interface through which parameters for setting the operating behavior are specified by a user, an algorithm, and/or other simulation-oriented computer program product. The computer program product may also have a data interface for outputting simulation results to a user and/or other simulation-oriented computer program products. The computer program product according to the invention has a map of the pressure measuring device to be simulated, which map can be executed in a physical module of the computer program product. By performing the mapping in the physical module, the operational behavior of the pressure measurement device can be simulated. For this purpose, the image of the pressure measuring device can be a spatially exact image of the pressure measuring device to be simulated in the physical module or can be a purely computational model which reproduces its operating behavior in an abstract form. Likewise, the physical module containing the map of the pressure measurement device may also be designed as a combination of the two. The computer program product may in particular be designed as a so-called digital twin, detailed in the publication US 2017/286572 A1 et al. The disclosure of US 2017/286572 A1 is incorporated herein by reference.

The computer program product according to the invention is based mainly on the surprising finding that: the mechanism of action on which the pressure measuring device according to the invention is based can be calculated in a simple manner. In particular, the use of computationally intensive finite element calculations can be minimized. Accordingly, the operating behavior of the pressure measuring device according to the invention can be simulated without difficulty. The pressure measuring device is designed for non-invasive pressure measurement, so that there is a relatively complex chain of action between the variable to be measured (i.e. the pressure in the pipe filled with fluid) and the measurement signal. Despite this complex chain of action, the computer program product according to the invention provides a higher fidelity in simulating the behavior of operations. The computer program product according to the invention is therefore also based on the following surprising findings: the construction of the pressure measuring device according to the invention provides such an improved fidelity. In many applications, for example in automation systems, a large number of devices and measuring devices are used which require the reproduction of their operating behavior in a process simulation at a control station (so-called operator control station). The computer program product according to the invention makes it possible to create an accurate process simulation with reduced hardware effort. Furthermore, the computer program product according to the invention can be used to plausibly check the measurement signals generated by the pressure measuring device in order to be able to identify defects in the simulated pressure measuring device itself or in other devices in the automation system. The computer program product according to the invention contributes overall to the operational reliability of the application in which the simulated pressure measurement device is used. Furthermore, the computer program product according to the invention enables the pressure measuring device to be tested and/or optimized in a simulated manner. The computer program product may be of monolithic design, i.e. may be executed entirely on a hardware platform. Alternatively, the computer program product may be of modular design, comprising several sub-programs that can be executed on several separate hardware platforms and interact via a communication data connection. Such a communication data connection may be a network connection or an internet connection. The computer program product may in particular be designed to be executable in a computer cloud.

Drawings

The invention will be elucidated in detail below with reference to embodiments in the drawings. These figures should be understood as complementary to each other, since the same reference numerals in different figures have the same technical meaning. The features of the various embodiments may also be combined with each other. Furthermore, the embodiments shown in the figures may be combined with the aforementioned features. Wherein:

fig. 1 is a longitudinal section of a first embodiment of the claimed pressure measurement device;

FIG. 2 is an oblique view of a first embodiment of the claimed pressure measurement device;

FIG. 3 is a detailed schematic view of a first embodiment of the claimed pressure measurement device;

FIG. 4 is a detailed schematic view of a second embodiment of the claimed pressure measurement device;

FIG. 5 is a stage of one embodiment of the claimed pressure measurement method.

Detailed Description

Fig. 1 shows a longitudinal section through a first embodiment of the claimed pressure measurement device 10. The pressure measurement device 10 is mounted on a pipe 11 at least partially containing a fluid 25 adapted to flow along a pipe axis 15 defining an axial direction 29. Fluid 25 is subjected to pressure 28, which includes static pressure and, in the presence of flow 27, dynamic pressure. The present pressure 28 exerts an expansive force on the tubular 11. The pressure measuring device 10 comprises a housing 12 which partly surrounds the pipe element 11 in order to transmit expansion forces acting in radial direction 23 on the pipe element 11 to the housing 12. The pressure measuring device 10 also comprises two tensile connecting members 14 which are subjected to a tensile load due to the pressure 28 present in the tube 11. At least one of the stretchable link members 14 has a grating 30 that can be illuminated by a light source 20. Furthermore, in the region of the stretchable connecting element 14, a detection element 16 is provided which is designed to detect a diffraction pattern 39, not shown in detail in the figure, which is produced as a result of the grating 30 being illuminated 22 by the light source 20. The assembled state shown in fig. 1 is a first step 110 of a pressure measurement method 100 that can be carried out with a pressure measurement device 10, in which a pipe 11 with a fluid 25 is provided and the pressure measurement device 10 is mounted on the pipe. Therein, the first step 110 represents an initial state, which is followed by a second step 120, in which the grating 30 is illuminated with the light source 20. The diffraction pattern 39 detected by the detection member 16 is forwarded in the form of a measurement signal 45 to an evaluation unit 40 which is at least functionally coupled to the pressure measuring device 10. In this case, the measurement signal 45 may be transmitted in a wired or wireless manner. To determine the pressure 28 in the pipe 11, a third step 130 and a fourth step 140 of the method 100 are also carried out on the evaluation unit 40. Furthermore, the evaluation unit 40 is adapted to control the light source 20 by means of control instructions 47. The pressure measuring device 10 forms a pressure measuring system 50 together with the evaluation unit 40. Furthermore, the pressure measurement device 10 is mapped in a computer program product 80, which is designed to simulate the operating behavior of the pressure measurement device 10. For this purpose, the computer program product 80 is designed as a digital twin.

Fig. 2 shows an oblique view of a first embodiment of the claimed pressure measurement device 10 as shown in fig. 1. The pressure measuring device 10 has two substantially C-shaped or arcuate housings 12 which partially enclose a tube 11, not shown in the figures, in the assembled state. The expansion of the pipe elements 11 in the radial direction 23, i.e. perpendicular to the pipe element axis 15, is converted into a pressure force acting on the inner surface 13 of the housing 12, with which the housing 12 rests against the pipe elements 11 in the assembled state. The housings 12 are connected to each other by stretchable connecting members 14, which are fixed to the housings by fixing members 21, which may be designed as screws. In this manner, the stretchable linkage member 14 is detachably connected to the housing 12. The stretchable linking member 14 is oriented substantially tangentially, as viewed along the tube axis 15. An axial direction 24 and a circumferential direction 26 are defined by the tubular axis 15. Furthermore, the stretchable connecting member 14 is designed as a sheet or as a strip. Thus, the expansion of the tube 11 will transition to a substantially planar stress state in which the bending of the tensile connecting members 14 is minimized. In particular, the expansion of the tube 11 is converted into a tensile load 31 to which the stretchable link members 14 are subjected, which exerts an influence on the grating 30 formed on at least one of said stretchable link members 14. The deformation of the stretchable connecting member 14 due to the tensile load 31 belongs to the operational behavior of the pressure measurement device 10 and can be reproduced in a computer program product 80 on which the pressure measurement device is mapped.

Fig. 3 shows a detailed view of the stretchable linkage member 14 according to the first embodiment of the claimed pressure measurement device 10. According to a second step 120 of the pressure measuring method 100, the stretchable connecting member 14 is irradiated. The illumination 22 is here indicated by broken lines. Slits 24, which are oriented substantially in the axial direction 24 and through which a grating 30 is formed in the stretchable linking member 14, are formed side by side in the stretchable linking member 14. Due to the tensile load 31 in the circumferential direction 26, the stretchable linking member 14 is deformed relative to the unloaded state, and the grating 30 is also changed by this deformation. Under the tensile load 31, the slits 24 forming the grating 30 are widened and pulled apart, i.e. at least one slit spacing 36 is enlarged. The tensile load 31 also causes a transverse contraction 33 in the axial direction 24, which can be quantified, for example, by the so-called poisson ratio. The deformation of the stretchable linkage members 14 occurs substantially in the elastic range, and therefore the effects of the increased gap spacing 36 and the transverse contraction 33 can be reversed by reducing the tensile load 31. The deformation of the stretchable linkage member 14 is further superimposed with the thermal expansion 35 of the stretchable linkage member 14. The thermal expansion 35 is dependent on the current temperature 32 of the stretchable link member 14. The thermal expansion 35 occurs uniformly in all directions and also acts on the grating 30. In general, at the stretchable linkage member 14, the current temperature 32 and the pressure 28 present in the tube 11 induce deformation of the grating 30. The grating 30, as a result of being illuminated 22, creates a diffraction pattern 39 on the side of the stretchable linkage member 14 away from the light source 20. This diffraction pattern 39 can be detected by means of the detection member 16, for example as shown in fig. 1, in order to determine the current pressure 28 therefrom. The above deformation behavior can be calculated in a simple manner and pertains to the operation behavior of the pressure measuring device 10 using the stretchable connecting member 14 according to fig. 3. The mapping and simulation of the stretchable connecting members 14 belongs to a computer program product 80, not shown in detail in the figures, by means of which the operating behavior of the pressure measuring device 10 can be simulated.

Fig. 4 shows a second embodiment of the claimed stretchable link member 14 in a detailed view. The embodiment according to fig. 4 may be combined with the structures according to fig. 1 and 2, but is not limited thereto. The stretchable connecting members 14 according to fig. 4 have a grating 30 formed by rectangular openings 34 arranged in a grid or array. In a second step 120 of the claimed pressure measurement method 100, the grating 30 is illuminated by the light source 20. The illumination 22 causes the grating 30 to create a diffraction pattern 39 on the side of the stretchable linkage members 14 away from the light source 20. The grating 30 and the diffraction pattern 39 corresponding thereto are affected by deformation of the stretchable connecting member 14. This deformation is mainly caused by the tensile load 31, which is caused by the expansion of the tube 11, not shown in the figure, due to the increase of the pressure 28 present inside it. This results in a larger gap spacing 36 and a wider rectangular opening 34, as viewed in the axial direction 24. The tensile load 31 also causes a transverse contraction 33 of the tensile connecting member 14, which narrows the rectangular opening 34, viewed in the circumferential direction 26, and the corresponding gap spacing 36 is reduced. The state shown in fig. 4 also overlaps with the thermal expansion 35 of the stretchable link member 14. The thermal expansion 35 is caused by the current temperature 32 of the tensile connecting member 14, which increases the gap spacing 36 in the axial direction 24 and in the circumferential direction 26. Likewise, the rectangular opening 34 is widened in the axial direction 24 and the circumferential direction 26 by the thermal expansion 35. Thus, a deformation occurs at the grating 30, the components of which in the axial 24 and circumferential 26 directions can be distinguished and quantified by corresponding changes in the diffraction pattern 39 in these two directions. The influence of the tensile load 31 and the influence of the thermal expansion 35, which are caused solely by the pressure forces 28 present in the pipe 11, can thereby be quantified. This allows for convenient temperature compensation when implementing the pressure measurement method 100. The above deformation behavior can be calculated in a simple manner and pertains to the operation behavior of the pressure measuring device 10 using the stretchable connecting member 14 according to fig. 3. The mapping and simulation of the stretchable connecting members 14 belongs to a computer program product 80, not shown in detail in the figures, by means of which the operating behavior of the pressure measuring device 10 can be simulated.

Fig. 5 shows a stage of an embodiment of the claimed method 100 for measuring the pressure 28 in a pipe 11 at least partially filled with a fluid. In particular, fig. 5 shows a diagram 70 comprising two subgraphs 70.1, 70.2. The first partial diagram 70.1 and the second partial diagram 70.2 each have a vertical variable axis which indicates the intensity of the diffraction pattern 39

72. The sub-figures 70.1, 70.2 also have corresponding horizontal position axes 74, which respectively show the position along the circumferential direction 26 of the pipe 11, as shown for example in fig. 3 or fig. 4. The first sub-plot 70.1 shows the intensity distribution 41 produced by the diffraction pattern 39 used as the reference diffraction pattern 37. The reference diffraction pattern 37 is detected when the associated stretchable link member 14 is in a well-defined mechanical and thermal load state. Reference diffraction pattern 37 contains a central maximum 42 having a width 43. The width 43 is formed by points 76 on the intensity distribution 41 which are 50% of the maximum amplitude 75 at the central maximum 42. The central maximum 42 is followed by alternately occurring secondary minima 44 and secondary maxima 46, the circumferential position 77 of which is stored in the reference diffraction pattern 37.

The second sub-diagram 70.2 shows the intensity distribution 41 of the reproduced diffraction pattern 39 generated at the grating 30 of the tensile connecting member 14 subjected to the tensile load 31. In a third step 130 of pressure measurement method 100, diffraction pattern 39 is detected. Diffraction pattern 39 has a central maximum 42 with a reduced width 43 compared to reference diffraction pattern 37. A deviation of the widths 43 of the central maxima 42 of the reference diffraction pattern 37 and the diffraction pattern 39 can be detected in a third step 130. Alternatively or additionally, the circumferential position 77 of the corresponding secondary minimum 44 and/or secondary maximum 46 in the diffraction pattern 39 and the reference diffraction pattern 37 can also be detected. In this case, such secondary minima 44 or secondary maxima 46 in the diffraction pattern 39 and the reference diffraction pattern 37 will be classified as corresponding, as seen from the central maxima 42, as first, second, third, secondary minima 44 or secondary maxima 46, and so on. Furthermore, within the scope covered by the sub-graphs 70.1, 70.2, a certain number of secondary minima 44 and/or secondary maxima 46 can be detected in a simple manner. There are therefore a number of possible features on the basis of which the current diffraction pattern 39 can be compared, in particular quantifiable, with the reference diffraction pattern 37 in the third step 130. In a third step 130, deviations between the reference diffraction pattern 37 and the diffraction pattern 39 are detected, and in a fourth step 140, the pressure 28 present in the pipe 11 is determined using said deviations. The fourth step 140 can be implemented, for example, in software in the evaluation unit 40 of the pressure measurement system 50, to which the pressure measurement device 10 is also assigned. In a fourth step 140, the current pressure 18 is determined, for example, on the basis of a table of values, an algorithm and/or artificial intelligence. The result determined for the pressure 28 in the fourth step 140 pertains to the operating behavior of the pressure measuring device 10. The third and fourth steps 130, 140 may likewise be mapped in a computer program product 80 for simulating the operating behavior of the pressure measurement device 10. Likewise, the operation shown in FIG. 5 is also possible for more complex diffraction patterns 39 and/or diffraction patterns 39 oriented along the axial direction 24 with the horizontal position axis 74.

Claims

1. Pressure measuring device (10) comprising several housings (12) which are each intended to partially enclose a tube (11) filled with a fluid and are connected to one another by stretchable connecting members (14), characterized in that at least one of the stretchable connecting members (14) has a grating (30) which is designed to produce a diffraction pattern (39) which is variable under a tensile load (31).

2. Pressure measuring device (10) according to claim 1, characterized in that the tensile load (31) is oriented tangentially to the tube (11).

3. Pressure measuring device (10) according to claim 1 or 2, characterized in that the variable diffraction pattern (39) can be generated by irradiating (22) the grating (30) in a radial direction (23) of the tube (11).

4. Pressure measuring device (10) according to one of claims 1 to 3, characterized in that the grating (30) has at least one recess (24, 34) which is designed to produce a variable diffraction pattern (39) in dependence on the direction.

5. Pressure measuring device (10) according to one of claims 1 to 4, characterized in that a detection means (16) for detecting the diffraction pattern (39) is provided in one region of the grating (30).

6. Pressure measuring device (10) according to claim 5, characterized in that the detection means (16) are designed as an array, in particular a photodiode array, or as an image sensor.

7. Pressure measuring device (10) according to one of claims 1 to 6, characterized in that the pressure measuring device (10) is designed to be non-destructively detachable from the tube (11).

8. Pressure measuring device (10) according to one of claims 1 to 7, characterized in that the pressure measuring device (10) comprises at least two stretchable connecting members (14) each having one grating (30) for identifying a bending of the fluid-filled tube (11).

9. A method (100) of measuring a pressure (28) in a pipe (11) containing a fluid, comprising the steps of:

a) Providing the fluid-filled tube (11) and providing the fluid-filled tube (11) with a pressure measuring device (10) comprising several housings (12) which are connected to one another by a stretchable connecting member (14);

b) Illuminating at least one stretchable link member (14) having a grating (30) with a light source (20);

c) Detecting the diffraction pattern (39) produced by said irradiation (22) in step b) and determining the difference between said detected diffraction pattern (39) and a reference diffraction pattern (37);

d) Determining the pressure (28) present in the fluid-filled pipe (11) based on the difference detected in step c).

10. The method (100) of claim 9, wherein the grating (30) is oriented tangential to the tube (11).

11. The method (100) according to claim 9 or 10, wherein the deformation of the grating (30) in the circumferential direction (26) and/or the deformation of the grating (30) in the axial direction (24) is determined in step c).

12. Method (100) according to one of claims 9 to 11, characterized in that in step c) the total intensity of the diffraction pattern (39), the width (43) of a central maximum (42), the intensity of the central maximum (42), the number of secondary maxima (46), the circumferential position (77) of a secondary maximum (46), the number of secondary minima (44) and/or the circumferential position (77) of a secondary minimum (44) is detected.

13. A pressure measurement system (50) for measuring a pressure (28) in a pipe (11) containing a fluid, comprising a pressure measurement device (10) connectable to a light source (20), the pressure measurement device being coupled to an evaluation unit (40), characterized in that the pressure measurement device (10) is designed according to any of claims 1 to 8 and/or the evaluation unit (40) is designed for carrying out a method (100) according to any of claims 9 to 12.

14. A computer program product (80) for simulating the operating behavior of a pressure measuring device (10) arranged on a pipe (11) filled with a fluid, characterized in that the pressure measuring device (10) is designed according to any one of claims 1 to 8.