Pressure transducer

Abstract

A pressure measuring sensor for measuring a pressure (p), in particular an overload-resistant measuring sensor, is described, comprising a pressure sensor (5) which is arranged in an interior space (3) of a sensor housing (1) and can be exposed to a medium under the pressure to be measured (p) through an opening (7) in the sensor housing (1), by means of which the pressure measuring sensor can measure a higher pressure of a medium, in particular a hydrogen-containing medium, under the pressure to be measured at a high measuring accuracy, in particular up to 1000 bar. The pressure measuring sensor is characterized in that the pressure sensor (5) is mounted on a connection element (9) which projects into the interior space (3) and is independent in the interior (3), such that the pressure sensor (5) is exposed to the pressure (p) prevailing in the interior space (3) on all sides; the pressure sensor comprises two ceramic measuring bodies (13, 15, 13', 15') which are connected to one another while enclosing a pressure chamber (11) and each of which can be deformed by the pressure (p) acting thereon; and the pressure sensor comprises an electromechanical transducer which converts a mechanical variable which depends on the sum of the pressure-dependent deformations of the two measuring bodies (13, 15, 13', 15') into a detectable electrical measuring variable.

Description

Technical Field

[0001] The present invention relates to a pressure measuring sensor for measuring pressure using a pressure sensor, wherein the pressure sensor is arranged inside a sensor housing and can be exposed to a medium under the pressure to be measured through an opening in the sensor housing. Background Technology

[0002] Pressure measurement sensors are specifically used in measurement and regulation technologies, and also in the automation of pressure measurement processes.

[0003] Pressure measurement sensors can be divided into two groups. One group comprises pressure measurement sensors whose pressure sensors are directly exposed to the pressure to be measured. These pressure measurement sensors include ceramic pressure sensors having a rigid substrate and a measuring diaphragm disposed on the substrate while enclosing a pressure chamber, and capable of deformation by pressure acting upon it. Due to the high chemical and mechanical resistance of ceramics, ceramic pressure sensors can be directly exposed to the medium at the pressure to be measured. The other group comprises pressure measurement sensors whose pressure sensors withstand the pressure to be measured via a diaphragm seal connected upstream of the pressure sensor. The diaphragm seal includes a separating diaphragm capable of withstanding pressure on its outer side, and a pressure receiving chamber filled with a pressure-transmitting liquid is enclosed below the separating diaphragm. Similarly, a liquid-filled pressure-transmitting line is connected to the pressure receiving chamber, through which the pressure is transmitted to the pressure sensor.

[0004] Applications exist where the medium under the test pressure contains hydrogen. Examples of these applications include those in the chemical and semiconductor industries, and increasingly, those associated with the use of renewable energy. The latter includes, for example, applications related to generating hydrogen through water electrolysis, storing hydrogen in hydrogen tanks, and filling hydrogen tanks, as well as applications related to generating energy through fuel cells, such as those used in the automotive industry, particularly in automobiles, buses, trucks, and trains. In these applications, very high test pressures may occur in certain situations.

[0005] In the case of diaphragm seals with metal separators, such as stainless steel separators, the following problem often arises: hydrogen present in the medium may diffuse through the separator. Hydrogen permeating the diaphragm seal causes changes in the pressure transmission characteristics of the diaphragm seal, which in turn leads to corresponding measurement errors in pressure measurements performed using the diaphragm seal. Furthermore, hydrogen permeating into the metal separator often causes embrittlement of the separator, which in turn leads to a significant deterioration in mechanical stability. Embrittlement of the separator can cause cracks or even diaphragm breakage, leading to diaphragm seal failure, and in some cases, contamination of the medium under the measured pressure by the pressure-transmitting liquid.

[0006] This problem can be solved by applying a layer to the outside of the separating membrane, and this layer is designed as a hydrogen diffusion barrier, such as a gold layer or a gold-rhodium layer. As an alternative, DE 10 2006056 173A1 describes a membrane seal having a separating membrane made of stainless steel, with an alumina layer disposed on the outside of the separating membrane. Alumina has a hydrogen diffusion coefficient significantly lower than that of a metal layer. Therefore, this alumina layer serves as a highly efficient hydrogen diffusion barrier.

[0007] However, regardless of the choice of layer material, it is impossible to completely rule out the possibility of damage points or even cracks appearing in the layer over time, especially due to improper handling, which would impair its function as a hydrogen diffusion barrier.

[0008] In this regard, due to the low hydrogen diffusivity in ceramics, the ceramic pressure sensor's entirely ceramic measuring membrane provides significantly better and more durable protection against hydrogen diffusion. Ceramic pressure sensors are typically clamped within a sensor housing, allowing only the measuring membrane of these sensors to penetrate an opening in the housing and be exposed to the medium at the measured pressure. To prevent thermomechanical stress caused by the difference in thermal expansion coefficients between the metal sensor housing and the ceramic pressure sensor from adversely affecting achievable measurement accuracy, a clamping device is typically used. In this device, the outer edge of the pressure sensor is clamped within the sensor housing, with a seal in the middle to seal the interior of the housing from the medium, thus allowing the measuring membrane to penetrate an opening in the housing and be exposed to the medium at the measured pressure. An example of this is described in DE 103 34 854A1.

[0009] However, the pressure measurement range of these pressure sensors is limited by the deformability of the seals and the magnitude of the clamping forces required to hold the pressure sensor, which increase with increasing pressure. For example, very high forces acting on the O-ring can cause the sealing material of the O-ring to irreversibly squeeze into the gap around the pressure sensor in the sensor housing, ultimately leading to seal failure. Therefore, pressures typically only within the range of 100 bar or less can be measured using these pressure sensors. Higher pressures—e.g., up to 400 bar—can be measured in certain situations with special precautions, particularly regarding clamping.

[0010] Another problem is that the sealing materials used to seal the interior of the sensor housing from the medium acting on the measuring diaphragm—such as elastomers or thermoplastics—are not diffusion-resistant. This means that hydrogen present in the medium can permeate into the interior of the sensor housing with almost no obstruction. This is undesirable or even unacceptable for explosion-proof purposes, especially in the case of pressure measurement sensors used in potentially explosive areas.

[0011] The problem of diffusion prevention can be solved by mounting the pressure sensor in the sensor housing using a diffusion prevention connector. An example of this is described in German patent application DE10 2018 123041A. The pressure measurement sensor described therein includes a ceramic pressure sensor arranged inside the sensor housing and exposed to the medium under the pressure to be measured through an opening in the sensor housing.

[0012] In this pressure measurement sensor, the sensor housing is a titanium carrier frame comprising a separate tubular carrier region extending parallel to the surface normal of the measuring membrane. An exemplary embodiment specifies that the end region of the carrier opposite the opening has a radially inwardly extending shoulder abutting the end of the tubular carrier region. In this variation, the outer edge of the shoulder-facing end face of a rigid substrate connected to the measuring membrane while enclosing the pressure chamber is connected via an anti-diffusion joint to an inner edge region of the shoulder, which is spaced apart from the tubular carrier region. The end region of the carrier opposite the shoulder connects to a process connector made of stainless steel, through which the interior of the carrier can withstand the measured pressure. In this case, the tubular carrier region serves to thermomechanically decouple the pressure sensor and the process connector. For this purpose, the tubular carrier region preferably has a small wall thickness of 1 mm to 2 mm.

[0013] However, the pressure measurement range of this type of pressure sensor is limited to low pressures, such as pressures less than or equal to one bar. One reason for this is the limited pressure resistance of the ring joint, which is only exposed to the pressure being measured on its outer side.

[0014] In principle, a ceramic pressure sensor can be designed with appropriate dimensions, featuring a rigid substrate and a measuring diaphragm mounted on the substrate while enclosing the pressure chamber. This allows for the measurement of very high pressures, such as 400 bar or higher. To enable the pressure sensor to withstand overloads exceeding its measurement range, at least temporarily, the diaphragm thickness should be greater than the thickness required for pressure measurements within the measurement range. However, this excessive thickness inevitably leads to a reduction in pressure-related deformation of the diaphragm when subjected to pressures within the measurement range; this deformation is often referred to as diaphragm travel. Therefore, the overload resistance gained by increasing the diaphragm thickness comes at the cost of achievable pressure measurement accuracy within the measurement range. Summary of the Invention

[0015] The purpose of this invention is to specify a pressure measurement sensor, particularly an overload resistant pressure measurement sensor, which enables the measurement of a medium under a test pressure, especially a high pressure of a hydrogen-containing medium, particularly a pressure up to 1000 bar, with high measurement accuracy.

[0016] For this purpose, the present invention includes a pressure measuring sensor for measuring pressure using a pressure sensor, wherein the pressure sensor is arranged inside a sensor housing and can be exposed to the medium under the pressure to be measured through an opening in the sensor housing.

[0017] The pressure sensor is characterized by:

[0018] It is mounted on a connecting element that protrudes into the interior and is independent inside, so that the pressure sensor is exposed on all sides to the pressure that is present inside.

[0019] It includes two measuring bodies connected to each other while enclosing the pressure chamber, and each measuring body is deformable by the pressure acting upon it; and

[0020] It includes an electromechanical transducer that converts a mechanical variable, which depends on the sum of pressure-related deformations of the two measuring bodies, into a measurable electrical variable.

[0021] Because the pressure acts substantially uniformly on all sides of the pressure sensor internally and similarly on all sides of the connecting element internally and connected to the pressure sensor externally, the pressure measuring sensor according to the invention provides the advantage that even under very high pressures, the mechanical connection between the pressure sensor and the connecting element is actually exposed to negligible or only very low forces. This is particularly true because the pressure acting externally on one side of the connecting element and the mechanical connection is offset by the same magnitude of pressure acting on the opposite side of the respective connecting element or the respective mechanical connection. This pressure similarly acts on the pressure sensor such that virtually no tensile or shear load is applied to the mechanical connection by the pressure acting on the pressure sensor.

[0022] Another advantage is that, by appropriately sizing the two interconnected measuring bodies, very high pressures can be measured, for example, pressures up to 1000 bar or even higher. Because the pressure sensor is directly exposed internally to the medium at the pressure to be measured, the achievable measurement accuracy is not affected by the possible pressure-dependent and temperature-dependent pressure transmission behavior of the diaphragm seal upstream of the pressure sensor.

[0023] Furthermore, the fact that each of the two measuring bodies can deform under pressure provides the advantage that pressure measurement occurs based on the sum of the pressure-related deformations of the two measuring bodies. Thus, high measurement accuracy can be achieved even if the thickness of the two measuring bodies is set to allow them to withstand overloads exceeding the upper limit of the pressure sensor's measurement range. Alternatively, a higher upper limit of the measurement range can, of course, be used. In this case, the overload resistance is correspondingly reduced relative to overloads exceeding the higher upper limit of the measurement range.

[0024] The first development plan is characterized by:

[0025] At least one or each of the connecting elements is designed in each case as a conductive connecting wire, the end of which is connected via a conductive mechanical connector to an associated electrical connector of the pressure sensor, which is disposed on the outside of the pressure sensor.

[0026] Each connecting element, designed as a connecting line, extends through the housing wall in a manner electrically insulated from the housing wall by a pressure-resistant feedthrough inserted into the housing wall of the sensor housing.

[0027] The first advancement is characterized by each feeder being: designed to prevent hydrogen diffusion, designed to be a ceramic feeder or a glass feeder, and / or designed to withstand pressures exceeding the upper limit of the pressure sensor's measurement range, pressures exceeding the pressure sensor's overload resistance, and / or pressures up to 1700 bar or 2000 bar.

[0028] An embodiment of the first advancement is characterized in that each feedthrough is arranged in the housing wall region opposite the opening of the sensor housing.

[0029] The second advancement is characterized by: a sensor housing surrounding the interior, made of metal or stainless steel, which is resistant to hydrogen diffusion, and / or designed to withstand pressures exceeding the upper limit of the pressure sensor's measurement range, pressures exceeding the pressure sensor's overload resistance, and / or pressures up to 2000 bar.

[0030] The third advancement is characterized in that the pressure sensor is connected to one end of each connecting element via a mechanical connector, a mechanical conductive connector, or a connector designed to be welded, such that the connector is exposed on all sides externally to the pressure that is present internally.

[0031] The fourth advancement is characterized by: connecting elements designed as straight, curved, or other rod-like elements, having an independent length of 1 mm to 10 mm internally, a diameter of 0.25 mm to 3 mm, and / or 0.05 mm. 2 Up to 7mm 2 The cross-sectional area is designed as a metal connecting element, made of Stainless steel, nickel, copper, nickel-iron alloy, copper-nickel alloy, molybdenum, It may be made of constantan and / or surrounded by a sheath or insulation.

[0032] The fifth development scheme is characterized by:

[0033] The pressure sensor is designed as an absolute pressure sensor, which measures the pressure acting on two measuring bodies as an absolute pressure relative to the generally present internal pressure in the pressure chamber, the internal pressure configured as vacuum pressure, or an internal pressure on the order of 1 bar.

[0034] The two measuring bodies are connected to each other via a pressure-resistant connector or a pressure-resistant and hydrogen-diffusion-proof connector, wherein the connector surrounds the pressure chamber on all sides externally.

[0035] Other development plans are characterized by:

[0036] The two measuring bodies are made of glass and are connected to each other via a connector that surrounds the pressure chamber on all sides externally, or via a connector that surrounds the pressure chamber on all sides externally and includes a glass ring and / or glass welds, or

[0037] The two measuring bodies are made of metal or stainless steel and are connected to each other via a connector that surrounds the pressure chamber on all sides externally, or via a connector that surrounds the pressure chamber on all sides externally and includes welded joints, or

[0038] The two measuring bodies are made of ceramic and are connected to each other via a connector that surrounds the pressure chamber on all sides externally, wherein the connector:

[0039] Designed for active brazing or glass welding, or

[0040] Including rings or rings formed as ceramic rings, wherein the ring:

[0041] Each of the two measuring bodies is connected to the other via a hydrogen diffusion-proof joint or via a joint designed to be produced by laser welding, in a manner that prevents hydrogen diffusion.

[0042] Alternatively, it may be designed as a component of one of two measuring bodies and connected to the other measuring body in a manner that prevents hydrogen diffusion, either via a hydrogen diffusion-proof joint or via a joint designed to be produced by laser welding.

[0043] The sixth further advancement is characterized in that the transducer of the pressure sensor is connected via a connecting element to a sensor electronics disposed on the outside of the sensor housing, the sensor electronics being designed to provide a measurement signal that reproduces the pressure measured by the pressure sensor.

[0044] The seventh development plan is characterized by:

[0045] The transducer includes a measuring electrode disposed on the inner side of one of the two measuring bodies, which, together with a counter electrode disposed on the inner side of the other measuring body facing that measuring body, forms a capacitor having a measuring capacitance that depends on the sum of the pressure-related deformations of the two measuring bodies.

[0046] The measuring electrode and the counter electrode are each electrically connected to a connector arranged on the outside of the pressure sensor via a connecting line extending through one of the two measuring bodies or via a contact pin extending through one of the two measuring bodies.

[0047] The seventh advancement is characterized by a contact pin electrically connected to a counter electrode disposed on the inner side of one of the two measuring bodies: traveling through the other measuring body opposite the counter electrode, and electrically connected to the counter electrode via a conductive connector that connects the two measuring bodies to each other, or extending through the connector that connects the two measuring bodies to each other, to the region of the counter electrode adjacent to the end face of the measuring body opposite to the contact pin of the connector.

[0048] The eighth advancement is characterized in that these measuring bodies are made of ceramic, glass, metal or stainless steel.

[0049] Another advancement is characterized in that the pressure sensor is designed to measure pressure within a pressure measurement range of greater than or equal to 400 bar and / or less than or equal to 1000 bar, and / or the pressure sensor is designed to be overload resistant to overloads up to 1800 bar or 5500 bar exceeding the upper limit of the pressure sensor measurement range.

[0050] Another development is characterized by the fact that each measuring body is designed to be substantially disc-shaped, or structurally identical substantially disc-shaped, and each of these measuring bodies has a diameter of 200 mm. 2 Up to 1300mm 2 The base area and / or thickness of 5mm to 10mm. Attached Figure Description

[0051] The invention and its advantages will now be explained in detail using the accompanying drawings, which illustrate two exemplary embodiments. Identical parts are given the same reference numerals in the drawings. To represent parts of very different sizes, it is not necessary to show them to scale.

[0052] Figure 1 A pressure measurement sensor is shown;

[0053] Figure 2 It shows Figure 1 An alternative embodiment of the connector between the two measuring bodies;

[0054] Figure 3 It shows Figure 1 The inner side of one of the measuring bodies;

[0055] Figure 4 Another pressure measurement sensor is shown; and

[0056] Figure 5 A metal pressure sensor is shown. Detailed Implementation

[0057] Figure 1A pressure measuring sensor is shown, which has a sensor housing 1 and a pressure sensor 5 disposed inside the interior 3 of the sensor housing 1. The pressure sensor 5 can pass through an opening 7 in the sensor housing 1 and be exposed to the medium at the pressure to be measured p.

[0058] Furthermore, the pressure sensor 5 is mounted in the interior 3 on a connecting element 9 that protrudes into and is independent of the interior 3, so that the pressure sensor 5 is exposed on all sides to the pressure p that is present throughout the interior 3.

[0059] The pressure sensor 5 includes two measuring bodies 13 and 15, which are connected to each other while enclosing the pressure chamber 11, and each measuring body is deformable by a pressure p acting upon it. As an example, Figure 1 Two substantially identical disc-shaped measuring bodies 13 and 15 with the same thickness d are shown. This generally symmetrical sensor structure offers the advantage that the two measuring bodies 13 and 15 contribute equally to the overload resistance of the pressure sensor 5, enabling a correspondingly high overload resistance of the pressure sensor 5 with appropriate sizing of the two measuring bodies 13 and 15. However, alternatively, measuring bodies of different thicknesses, each capable of deformation in a pressure-dependent manner, can be used within the pressure measurement range of the pressure sensor.

[0060] Figure 1 The pressure sensor 5 shown as an example is designed as a ceramic pressure sensor. For example, a suitable ceramic for the pressure sensor 5 is an oxide ceramic, such as alumina (Al2O3), and the two measuring bodies 13 and 15 are preferably made of the same ceramic.

[0061] Regardless of the embodiment of the measuring bodies 13 and 15 in this respect, the pressure sensor 5 includes an electromechanical transducer that converts a mechanical variable, which depends on the sum of the pressure-related deformations of the two measuring bodies 13 and 15, into a measurable electrical variable.

[0062] This electrical measurement variable can be measured, for example, by a sensor electronics 17 that can be connected to or connected to a transducer, and can be converted into a measurement signal that reproduces the measured pressure. The sensor electronics 17 can optionally be arranged inside or outside the interior 3 of the sensor housing 1, such as... Figure 1 As shown. Arranging the sensor electronics 17 on the outside of the sensor housing 1 provides the following advantages: the sensor electronics 17 is not exposed to the pressure present in the sensor housing 1, and therefore there is no need to perform corresponding pressure-resistant encapsulation on the sensor electronics 17.

[0063] As an example, Figure 1A capacitive transducer is shown, comprising a measuring electrode 19 disposed on the inner side of one of two measuring bodies 13, and together with a counter electrode 21 disposed on the inner side of the other measuring body 15 facing the measuring body 13, forming a measuring capacitance C. p The capacitor, whose measured capacitance depends on the sum of the pressure-related deformations of the two measuring bodies 13 and 15. In this case, the sensor electronics 17 includes, for example, a capacitance measurement circuit connected to the capacitor and outputting the measured capacitance C. p The corresponding measurement signal. Optionally, the transducer may additionally include a reference capacitor having a reference capacitance C that is substantially independent of pressure. ref As an example, Figure 1 A reference capacitor is shown, formed by a reference electrode 23 and a counter electrode 21, the reference electrode surrounding and spaced apart from the measuring electrode 19. In this case, the measurement signal corresponds to a measurement capacitor C. p and reference capacitor C ref The measured variable is determined and reproduced as the measured pressure. For example, the measured variable can be determined as the product of a constant k and the difference between the reciprocals of the two capacitors, using the following formula: f = k(C p -C ref ) / C p This measured variable has a linear correlation with the pressure p being measured, and also with the measured capacitance C. p It has a lower temperature dependence compared to other methods.

[0064] Alternatively, instead of the transducers shown here, capacitor transducers of different designs or transducers based on other transducer principles, such as resistive transducers or optical transducers, can be used.

[0065] The pressure measuring sensor according to the invention has the advantages already mentioned at the outset. The various components of the pressure measuring sensor can each have different embodiments, and these embodiments can be used individually or in combination. Optionally, for example, the sensor housing 1 is made of metal, such as stainless steel. Optionally or additionally, the interior 3 of the sensor housing 1 is surrounded, for example, by a hydrogen-resistant, pressure-resistant housing wall 25. The greater the wall thickness of the housing wall 25, the higher the pressure resistance of the sensor housing 1. Optionally, the pressure resistance can also be further increased by shaping the housing wall 25.

[0066] In this regard, the sensor housing 1 is designed, for example, to withstand pressure p exceeding the upper limit of the measurement range of the pressure sensor 5, pressure p exceeding the overload capacity of the pressure sensor 5, and / or pressure p up to 2000 bar. For this purpose, the housing wall 25 preferably has a wall thickness predetermined according to its geometry and the material of the housing wall 25, by which pressure resistance corresponding to the desired pressure resistance of the sensor housing 1 is ensured. The pressure resistance of the sensor housing 1 exceeding the overload capacity of the pressure sensor 5 provides the advantage that the sensor housing 1 can withstand pressure p that would damage the pressure sensor 5. This ensures that these extreme overloads cannot pass through the sensor housing 1, and therefore cannot cause any damage to the outside of the sensor housing 1 or around the pressure measuring sensor.

[0067] The greater the wall thickness of the outer casing 25, the lower the hydrogen diffusion rate that any hydrogen present in the medium inside the interior 3 can diffuse through the outer casing 25. Therefore, by setting the corresponding dimensions of the wall thickness, the desired hydrogen diffusion resistance of the sensor casing 1 can also be ensured simultaneously.

[0068] By setting the wall thickness of the sensor housing 1 accordingly, the sensor housing 1 can be made resistant to hydrogen diffusion, which provides the following advantages: any hydrogen present in the medium cannot pass through the sensor housing 1, and therefore does not cause any damage to the outside of the sensor housing 1.

[0069] For the application of pressure, the pressure measurement sensor may include, for example, a process connection 27, such as... Figure 1 The flange formed on the sensor housing 1, as shown, allows the pressure sensor to be mounted on a complementary process connector, which is located at the point of use and conducts the medium. Alternatively, other process connector variations known in the art and suitable for mounting the pressure sensor and / or applying pressure to the interior 3 may be used.

[0070] Furthermore, the pressure sensor 5 is designed, for example, as an absolute pressure sensor, which measures the pressure p acting on the two measuring bodies 13, 15 as an absolute pressure relative to the internal pressure generally present in the pressure chamber 11. In particular, vacuum pressure is suitable as the internal pressure. In this case, the pressure chamber 11 enclosed between the measuring bodies 13, 15 is evacuated. However, alternatively, an internal pressure lower than the measured pressure p, for example, an internal pressure on the order of 1 bar, can be used as the internal pressure. An internal pressure of 1 bar, on the order of atmospheric pressure, offers the advantage of being easier to set up than vacuum pressure in production engineering. Compared to a pressure measuring sensor with a pressure sensor designed as a relative pressure sensor, an absolute pressure sensor does not require a reference pressure supply extending through the housing wall 25 and one of the two measuring bodies 13, 15 to pressurize the pressure chamber 11 using a reference pressure. This offers the advantage that, utilizing the corresponding pressure resistance of the sensor housing 1, even an overload that would cause the pressure sensor 5 to fail cannot pass through the sensor housing 1.

[0071] The two measuring bodies 13, 15 are connected, for example, by a pressure-resistant connector 29, which connects the outer edge of one measuring body 13 to the outer edge of the other measuring body 15 and surrounds the pressure chamber 11 on all sides of the exterior.

[0072] Suitable pressure-resistant connectors 29 connected to the measuring bodies 13, 15 made of ceramic are, for example, active brazing, such as active brazing produced by zirconium nickel titanium active brazing flux.

[0073] Alternatively, connector 29 is designed, for example, to be pressure-resistant and prevent hydrogen diffusion. For this purpose, connector 29 is designed, for example, to be glass welded.

[0074] As a further alternative, the pressure-resistant and hydrogen diffusion-proof connector 29' of the two measuring bodies 13 and 15 can, for example, be... Figure 2 The arrangement is as shown, wherein two measuring bodies 13, 15 are connected to each other via a hydrogen diffusion-protected ring 31, such as a ceramic ring, which in each case is connected to the two measuring bodies 13, 15 via a hydrogen diffusion-protected joint 33—for example, a welded joint produced by a ceramic welding method such as laser welding. For example, a laser welding method capable of laser welding ceramic measuring bodies 13, 15 is described in DE10 2011 004 722A1. Alternatively, the ring 31 may be formed as an integral part of one of the two measuring bodies 13 or 15, which is connected to the other measuring body 15 or 13 via the hydrogen diffusion-protected joint 33.

[0075] When the pressure sensor 5 is designed as an absolute pressure sensor, and the pressure measurement sensor is used to measure the pressure of a hydrogen-containing medium, it is particularly advantageous to construct the connectors 29 and 29' as hydrogen diffusion-resistant connectors. Here, the combination with relatively thick measuring bodies 13 and 15, which similarly form a long-term stable, high-quality hydrogen diffusion barrier due to the extremely low hydrogen diffusivity in ceramics, provides the advantage of providing high-quality, permanent protection for the pressure chamber 11 to prevent hydrogen from seeping into it. This provides the advantage that the pressure p of the hydrogen-containing medium can be measured even over very long periods without affecting the achievable measurement accuracy.

[0076] Optionally, the pressure transducer is designed to measure very high pressures p, such as pressures greater than or equal to 400 bar and / or up to 1000 bar, or even higher. For this purpose, the base area and thickness d of the two measuring bodies 13, 15 are preferably sized according to the pressure measurement range of the pressure sensor 5, and possibly also the desired overload resistance. For a measured pressure p up to 1000 bar, each of the two disc-shaped measuring bodies 13, 15 has, for example, a thickness of 200 mm. 2 Up to 1300mm 2 The base area and / or thickness d of 5mm to 10mm. Combined with 200mm 2 Up to 1300mm 2 The base area of ​​the measuring bodies 13 and 15, with a thickness d greater than or equal to 5 mm, provides the following advantages: the measuring bodies 13 and 15 can easily withstand overloads exceeding the upper limit of the pressure measurement range of 1000 bar. The smaller the deflectable base area and the larger the thickness d of the measuring bodies 13 and 15, the stronger their overload resistance.

[0077] Conversely, a thickness of 10 mm or less ensures that the sum of the pressure-related deformations of the two measuring bodies 13 and 15 is large enough to measure pressures far below the upper limit of the pressure measurement range, such as pressures from 400 bar to 1000 bar, while maintaining relatively high measurement accuracy.

[0078] Consider, by way of example, two disc-shaped measuring bodies 13 and 15, each with a diameter of 17.5 mm and a thickness d of 5 mm, and whose outer edges are connected to each other by annular connectors 29 and 29' with a rectangular cross-section having a height of 0.018 mm and a radial width of 3.3 mm. When a pressure of 400 bar is applied, the distance between the centers of the two measuring bodies is 15 μm, while when a pressure of 1000 bar is applied, the distance is 10.7 μm. Using this pressure sensor 5, overload resistance to very high overloads, such as up to 5500 bar, can be achieved.

[0079] Considering, as a second example, two disc-shaped measuring bodies 13 and 15, each with a diameter of 40 mm and a thickness d of 10 mm, and whose outer edges are connected to each other by annular connectors 29 and 29' with a rectangular cross-section having a height of 0.028 mm and a radial width of 6.6 mm, the distance between the centers of the two measuring bodies is 18.7 μm when a pressure of 400 bar is applied, and 4.8 μm when a pressure of 1000 bar is applied. Using this pressure sensor 5, for example, overload resistance up to 1800 bar can be achieved.

[0080] As demonstrated in the first example by the 4.3 μm distance change resulting from a pressure change of 400 bar to 1000 bar, or in the second example by the 13.9 μm distance change resulting from a pressure change of 400 bar to 1000 bar, the distance change between the centers of the measuring bodies occurring within the pressure measurement range is large enough to, for example, be transmitted through a capacitive transducer based on a measuring capacitance C that depends on the distance between the two measuring bodies 13 and 15. p This achieves relatively high measurement accuracy.

[0081] Specifically, when the measuring bodies 13 and 15 of the pressure sensor 5 have a relatively large base area, overload resistance can be achieved, for example, by increasing the thickness d of the measuring bodies 13 and 15 to a thickness d greater than or equal to 10 mm and / or by shrinking the area of ​​the measuring bodies 13 and 15 that can deform in a pressure-dependent manner. For example, the size of the area of ​​the measuring bodies 13 and 15 that can deform in a pressure-dependent manner can be reduced by correspondingly increasing the radial width of the annular connectors 29 and 29' connecting the outer edges of the measuring bodies 13 and 15. This widening of the connectors 29 and 29' also provides the advantage of increased resistance to hydrogen diffusion. This is particularly advantageous when the connectors 29 are formed by active brazing.

[0082] As previously described, the pressure sensor 5 is mounted on a separate connecting element 9 within the interior 3. For this purpose, the pressure sensor 5 is connected to one end of each connecting element 9, for example, via a mechanical connector 35, such that the connector 35 is exposed on all sides externally to the pressure p present inside the interior 3. A suitable mechanical connector 35 is, for example, a joint, such as a weld.

[0083] The connecting element 9 is designed as a straight, curved, or other shaped rod-like element, for example. Alternatively or additionally, the connecting element 9 is located inside the sensor housing 1 3, having an independent length L of 1 mm to 10 mm and / or a diameter of 0.05 mm corresponding to 0.25 mm to 3 mm. 2 Up to 7mm 2 The cross-sectional area.

[0084] Optionally, at least one or each of the connecting elements 9 used for mounting the pressure sensor 5 is also used for electrical connection of the pressure sensor 5. For this purpose, these connecting elements 9 are each designed as conductive connecting lines, the ends of which are each connected via mechanical connectors 35—in this case, conductive connectors—to an associated electrical connector 37 arranged in the interior 3 of the pressure sensor 5.

[0085] exist Figure 1 In this embodiment, connector 37 is an electrical connection 37 of the electromechanical transducer disposed on the outer surface of the pressure sensor 5. In an embodiment where the sensor electronics 17 is disposed in the sensor housing 1, the connector may also include at least one connector of the sensor electronics 17 connected to the transducer.

[0086] Suitable connecting wires are specifically connecting elements 9 made of metal, such as those made of... Stainless steel, nickel, copper, nickel-iron alloy, copper-nickel alloy, molybdenum, The connecting element 9 may be made of constantan. Alternatively, the connecting element 9 may be designed such that its internal independent length L is surrounded externally by a sheath, such as insulation.

[0087] Regardless of the construction in this regard, each of the connecting elements 9 designed as connecting lines extends through the housing wall 25 in a manner electrically insulated from the housing wall 25 by means of a pressure-resistant electrical feeder 39 inserted into the housing wall 25.

[0088] A suitable pressure-resistant feeder 39 is particularly a feeder 39 that is pressure-resistant to pressure p exceeding the upper limit of the measurement range of the pressure sensor 5, pressure p exceeding the overload resistance of the pressure sensor 5, and / or pressure p up to 2000 bar.

[0089] Feedthrough elements 39 are arranged, for example, within the housing wall region 41 of the sensor housing 1 opposite to the opening 7. Figure 1 An example is shown in which the sensor housing 1 is designed as a substantially pot-shaped housing, and the feedthrough 39 is inserted into the housing base opposite the opening 7.

[0090] Suitable pressure-resistant feeders 39 are particularly suitable for use with ceramic or glass feeders, which also provide protection against hydrogen diffusion. Glass and ceramic feeders are known in the art, and in addition to their high resistance to hydrogen diffusion due to the low diffusivity of hydrogen in ceramics or glass, these feeders are designed to withstand very high pressures, such as up to 1700 bar or even up to 2000 bar. For example, Alumina Systems GmbH in Redwitz, Germany, and CeramTec GmbH in Plochingen, Germany, provide suitable ceramic feeders. For example, HaTec Halebi Technik in Würzburg, Germany, provides suitable glass feeders.

[0091] exist Figure 1 In this configuration, the transducer of pressure sensor 5 is connected via a connecting element 9, designed as a connecting line, to sensor electronics 17, which is disposed on the outside of sensor housing 1. This variation offers the advantage that the pressure measurement range is not limited by the pressure resistance of sensor electronics 17, which is typically lower than that of pressure sensor 5 and sensor housing 1. Sensor electronics 17 is preferably disposed directly on the outside of sensor housing 1, away from the interior 3. As a result, the wire length of the conductive connection between the transducer and sensor electronics 17 remains low. The shorter wire length provides the advantage of reduced impact of electromagnetic interference signals and / or parasitic capacitance on achievable measurement accuracy.

[0092] Figure 3 It shows Figure 1 A view of the inner side of a measuring body 13, which is equipped with a measuring electrode 19 and a reference electrode 23, is shown, along with an example of the location of contact pins Km and Kref extending through the measuring body 13 for contacting the measuring electrode 19 and the reference electrode 23. Figure 3 The connector 29, indicated by the dashed line, is conductive between the two measuring bodies 13 and 15. Therefore, the counter electrode 21, located on the measuring body 15 opposite to the measuring electrode 19 and in conductive contact with the connector 29, can also be conductively connected via... Figure 3 The contact pin Kg, shown, extends through the measuring body 13 to the connector 29 for contact. If the two measuring bodies 13, 15 are connected via electrically insulating connectors 29, 29', such as, for example, glass bonding or... Figure 2 The rings 31 shown are connected to each other, so the electrical contact of the counter electrode 21 can be, for example, by... Figure 2This occurs as an option shown. Here, the contact pin Kg for contacting the reverse electrode 21 extends through one of the two measuring bodies 13 and the electrically insulating connector 29' to a region of the reverse electrode 21, which is adjacent to the end face of the connector 29' opposite to the measuring body 13 surrounding the contact pin Kg.

[0093] exist Figures 1 to 3 In the variant shown, all the connectors 37 of the pressure sensor 5 at the end of one of the contact pins Km, Kr, Kg are arranged adjacent to each other on a plane on the same outer side of the pressure sensor 5.

[0094] Figure 4 It shows Figure 1 A modification to the pressure measurement sensor, wherein the connector 37 of the pressure sensor 5 is arranged on the opposing outer sides of the pressure sensor 5. In this example, the measuring electrode 19 is connected to the connector 37 arranged on the outer side of one of the measuring bodies 13 via a contact pin Km extending through one of the measuring bodies 13, while the counter electrode 21 is connected to the connector 37 arranged on the outer side of the other measuring body 15 via a contact pin Kg extending through the other measuring body 15. Similar to... Figure 1 The example shown, Figure 4 The modification shown can of course also be fitted with a reference capacitor having a capacitance that is substantially independent of pressure, the reference capacitor including at least one electrode connected to a connector arranged on the outside of the pressure sensor 5 via a contact pin extending through one of the measuring bodies 13, 15.

[0095] Optionally, the pressure measurement sensor includes measurement electronics 43 connected to sensor electronics 17 and configured to determine and provide pressure measurement results p based on the measurement signal. gem For this purpose, measurement electronics known in the prior art can be used. Figure 1 The measurement electronics 43 shown as an example includes a signal processing unit 45 and a signal evaluation unit 47 downstream of the signal processing unit 45. The signal processing unit 45 is configured, for example, to amplify the measurement signal to filter out interference signals present in the measurement signal and / or smooth the measurement signal. The signal evaluation unit 47 is configured to determine and provide a pressure measurement result p based on the processed measurement signal. gem .

[0096] Although the invention has been described above using an example of a pressure sensor 5 with ceramic measuring bodies 13, 15, pressure sensors with measuring bodies 13, 15 made of other materials can also be used alternatively. Therefore, referring to... Figures 1 to 4The measuring elements 13 and 15 of the described pressure measuring sensor can be made of, for example, other insulators, such as glass. In this case... Figure 1 The connector 29 shown is, for example, a glass weld. Alternatively, measuring bodies 13, 15 made of glass can be used, for example, via a reference. Figure 2 The described connector 29' is used for connection. In this case, the ring 31 is, for example, a glass ring, which in various cases is connected via... Figure 2 One of the joints 33 shown, such as a joint formed, for example, by glass welding, is connected to one or both of the two measuring bodies 13, 15.

[0097] Depending on the application, in some cases even pressure sensors with measuring bodies 13' and 15' made of metal, such as stainless steel, can be used. Figure 5 An example of a pressure sensor is shown, which has two metal measuring bodies 13' and 15' connected to each other via a connector 49, such as a weld, while enclosing the pressure measuring chamber 11. This pressure sensor can also be designed, for example, as a capacitive pressure sensor. In this respect, Figure 5 The pressure sensor shown is Figure 1 and Figure 4 The pressure sensor 5 shown is essentially different only in that the electrodes of the transducer—such as Figure 5 The measuring electrode 19 shown and Figure 5 The counter electrodes 21 shown are each arranged such that the insulator 51 is inserted on one of the two opposing inner sides of the metal measuring bodies 13' and 15'. Figure 5 As an example, insulators 51 are shown, each designed as an insert, such as an insert made of glass or ceramic, which is inserted into one of the two measuring bodies 13', 15'. Similar to the exemplary embodiments described previously, the electrical connections of the transducers are implemented, for example, via connecting lines 53 connected to electrodes—such as measuring electrode 19 and counter electrode 21—whereby each connecting line is connected via a feedthrough 55 to one of the connectors 37 arranged on the outside of one of the pressure sensors, the feedthrough 55 such that the respective connecting line 53 is electrically insulated from the respective measuring bodies 13', 15'.

[0098] List of reference numerals

[0099] 1. Sensor housing 29, 29' connector

[0100] 3. Internal 31 rings

[0101] 5 Pressure sensor 33 Welding section

[0102] 7. Opening 35mm connector

[0103] 9 Connecting elements 37 Connecting pieces

[0104] 11 Pressure chamber 39 Feeder component

[0105] 13, 13' Measuring body 41 Outer shell wall area

[0106] 15, 15' Measuring body 43 Measuring electronic device

[0107] 17 Sensor Electronics 45 Signal Processing Unit

[0108] 19 Measurement electrodes 47 Signal evaluation unit

[0109] 21 Counter electrode 49 Connector

[0110] 23 Reference electrode 51 Insulator

[0111] 25 Outer wall 53 Connecting wire

[0112] 27 Process connector 55 Feeder

Claims

1. A pressure measuring sensor for measuring pressure (p) using a pressure sensor (5), wherein, The pressure sensor (5) is arranged inside (3) of the sensor housing (1) and is exposed to the medium under the pressure (p) to be measured through an opening (7) in the sensor housing (1). The pressure sensor (5) is characterized in that: The pressure sensor (5) is mounted on a connecting element (9) that protrudes into and is separate from the interior (3) such that the pressure sensor (5) is exposed on all sides to the pressure (p) that is present throughout the interior (3). It includes two measuring bodies (13, 15, 13', 15'), which are connected to each other while enclosing the pressure chamber (11), and each of the two measuring bodies is deformable by the pressure (p) acting upon it. It includes an electromechanical transducer that converts a mechanical variable, which depends on the sum of pressure-related deformations of two measuring bodies (13, 15, 13', 15'), into a measurable electrical measurement variable.

2. The pressure measuring sensor according to claim 1, characterized in that, At least one of the connecting elements (9) is designed in each case as a conductive connecting wire, the end of which is connected by a conductive mechanical connector (35) to an associated electrical connector (37) of the pressure sensor (5), the electrical connector being arranged on the outside of the pressure sensor (5). Each connecting element (9) designed as a connecting line extends through the housing wall (25) in an electrically insulated manner from the housing wall (25) via a pressure-resistant feedthrough (39) inserted into the housing wall (25) of the sensor housing (1).

3. The pressure measuring sensor according to claim 2, characterized in that, Each feeder (39): The feedthrough element (39) is designed to prevent hydrogen diffusion. Designed as a ceramic feedthrough (39) or a glass feedthrough, and / or Feeder (39) designed to withstand pressures (p) exceeding the upper limit of the measurement range of the pressure sensor (5), pressures (p) exceeding the overload resistance of the pressure sensor (5), and / or pressures (p) up to 1700 bar or 2000 bar.

4. The pressure measuring sensor according to claim 2, characterized in that, Each feedthrough (39) is arranged in the housing wall region (41) of the sensor housing (1) opposite to the opening (7).

5. The pressure measuring sensor according to claim 3, characterized in that, Each feedthrough (39) is arranged in the housing wall region (41) of the sensor housing (1) opposite to the opening (7).

6. The pressure measuring sensor according to any one of claims 1 to 5, characterized in that, The sensor housing (1) surrounding the interior (3): Composed of metal, It is to prevent hydrogen diffusion, and / or A sensor housing (1) is designed to withstand pressures (p) exceeding the upper limit of the measurement range of the pressure sensor (5), pressures (p) exceeding the overload resistance of the pressure sensor (5), and / or pressures (p) up to 2000 bar.

7. The pressure measuring sensor according to claim 6, characterized in that, The sensor housing (1) is made of stainless steel.

8. The pressure measuring sensor according to any one of claims 1 to 5, 7, characterized in that, The pressure sensor (5) is connected to one end of each connecting element (9) via a mechanical connector (35) or a connector (35) designed to be welded, such that the connector (35) is exposed on all sides to the pressure (p) that is present in the interior (3).

9. The pressure measuring sensor according to claim 8, characterized in that, The mechanical connector (35) is a mechanical conductive connector (35).

10. The pressure measuring sensor according to any one of claims 1 to 5, 7 and 9, characterized in that, The connecting element (9): Designed as straight or curved rod-shaped elements, The interior (3) has an independent length (L) of 1 mm to 10 mm. having a diameter of 0.25 mm to 3 mm and / or a cross-sectional area of 0.05 mm 2 to 7 mm 2 . Designed as a metal connecting element (9), from Kovar ® stainless steel, nickel, copper, nickel-iron alloy, copper-nickel alloy, molybdenum, Alumel ® or constantan, and / or It is surrounded by a sheath or insulation.

11. The pressure measuring sensor according to any one of claims 1 to 5, 7 and 9, characterized in that, The pressure sensor (5) is designed as an absolute pressure sensor, which measures the pressure (p) acting on the two measuring bodies (13, 15, 13', 15') as an absolute pressure relative to the internal pressure generally present in the pressure chamber (11), the internal pressure designed as a vacuum pressure, or the internal pressure on the order of 1 bar. The two measuring bodies (13, 15, 13', 15') are connected to each other via pressure-resistant connectors (29, 29'), wherein the connectors (29, 29') surround the pressure chamber (11) on all sides externally.

12. The pressure measuring sensor according to claim 11, characterized in that, The pressure-resistant connectors (29, 29') are pressure-resistant and hydrogen diffusion-proof connectors (29, 29').

13. The pressure measuring sensor according to any one of claims 1 to 5, 7, 9 and 12, characterized in that, The two measuring bodies (13, 15) are made of glass and are connected to each other via connectors (29, 29') surrounding the pressure chamber (11) on all external sides, or via connectors (29, 29') surrounding the pressure chamber (11) on all external sides and including glass rings and / or glass welds, or The two measuring bodies (13', 15') are made of metal and are connected to each other via a connector surrounding the pressure chamber (11) on all external sides, or via a connector surrounding the pressure chamber (11) on all external sides and including a weld (49), or The two measuring bodies (13, 15) are made of ceramic and are connected to each other via connectors (29, 29') surrounding the pressure chamber (11) on all sides externally, wherein the connectors (29, 29'): Designed for active brazing or glass welding, or Includes a ring (31), wherein the ring (31): The hydrogen diffusion is prevented by connecting each of the two measuring bodies (13, 15) via a hydrogen diffusion-proof joint (33) or via a joint (33) designed to be produced by laser welding. Alternatively, it may be designed as a component of one of the two measuring bodies and connected to the other measuring body in a manner that prevents hydrogen diffusion, either via a hydrogen diffusion-proof joint or via a joint designed to be produced by a laser welding method.

14. The pressure measuring sensor according to claim 13, characterized in that, The two measuring bodies (13', 15') are made of stainless steel.

15. The pressure measuring sensor according to claim 13, characterized in that, The ring (31) is formed as a ceramic ring.

16. The pressure measuring sensor according to any one of claims 1 to 5, 7, 9, 12, 14 to 15, characterized in that, The transducer of the pressure sensor (5) is connected via the connecting element (9) to a sensor electronics (17) arranged outside the sensor housing (1), the sensor electronics being designed to provide a measurement signal that reproduces the pressure measured by the pressure sensor (5).

17. The pressure measuring sensor according to any one of claims 1 to 5, 7, 9, 12, 14 to 15, characterized in that, The transducer comprises a measuring electrode (19) arranged on the inner side of one of the two measuring bodies (13, 13') and forming, together with a counter electrode (21) arranged on the inner side of the other measuring body (15, 15') facing the measuring body (13, 13'), a capacitor with a measuring capacitance (C p ) which depends on the sum of the pressure-dependent deformations of the two measuring bodies (13, 15, 13', 15). The measuring electrode (19) and the counter electrode (2) are each electrically connected to a connector (37) arranged on the outside of the pressure sensor (5) via a connecting line (53) extending through one of the two measuring bodies (13', 15') or via a contact pin (Km, Kg) extending through one of the two measuring bodies (13, 15).

18. The pressure measuring sensor according to claim 17, characterized in that, The contact pin (Kg) is electrically connected to the counter electrode (21) disposed on the inner side of one of the two measuring bodies (15): Extending through another measuring body (13) opposite to the counter electrode (21), and The two measuring bodies (13, 15) are electrically connected to the counter electrode (21) via a conductive connector (29) that connects them to each other. Alternatively, it can extend through the connector (29') that connects the two measuring bodies (13, 15) to each other, to the region of the reverse electrode (21) adjacent to the end face of the measuring body (13) opposite to the connector (29') surrounding the contact pin (Kg).

19. The pressure measuring sensor according to any one of claims 1 to 5, 7, 9, 12, 14 to 15, 18, characterized in that, The measuring bodies (13, 15, 13', 15') are made of ceramic, glass or metal.

20. The pressure measuring sensor according to claim 19, characterized in that, The measuring bodies (13, 15, 13', 15') are made of ceramic, glass or stainless steel.

21. The pressure measuring sensor according to any one of claims 1 to 5, 7, 9, 12, 14 to 15, 18, 20, characterized in that, The pressure sensor (5) is designed to measure pressure (p) within a pressure measurement range of greater than or equal to 400 bar and / or less than or equal to 1000 bar, and / or The pressure sensor (5) is designed to be overload resistant to pressure sensors (5) with overloads up to 1800 bar or up to 5500 bar exceeding the upper limit of the measurement range of the pressure sensor (5).

22. The pressure measuring sensor according to any one of claims 1 to 5, 7, 9, 12, 14 to 15, 18, 20, characterized in that, The measuring bodies (13, 15, 13', 15') are each designed as substantially disc-shaped measuring bodies (13, 15), each having a diameter of 200 mm. 2 Up to 1300mm 2 The base area and / or thickness (d) of 5 mm to 10 mm.

23. The pressure measuring sensor according to claim 22, characterized in that, The substantially disc-shaped measuring bodies (13, 15) are structurally identical substantially disc-shaped measuring bodies (13, 15).

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