Pressure sensor, pressure sensor assembly, and use of the pressure sensor
Patent Information
- Application Number
- EP2023717510
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-11
- Filing Date
- 2023-04-05
- Publication Date
- 2025-03-19
AI Technical Summary
Conventional pressure sensors fail to effectively measure hydrogen pressure due to hydrogen penetration, causing corrosion and damage, especially when made of metallic materials, which impairs the sensor's functionality.
A compact pressure sensor design with a conical sensor housing and a sealing element positioned away from the front end, preventing hydrogen from reaching the sensor housing and allowing for precise pressure measurement without the need for hydrogen-resistant materials, using a monolithic or separate sealing element with optimized material selection and thermal compensation.
The solution provides a cost-effective, precise, and durable pressure sensor that prevents hydrogen corrosion, maintaining sensor functionality and reducing production costs by avoiding the use of hydrogen-resistant materials, while ensuring effective sealing and thermal stability.
Smart Images
Figure 1.1
Abstract
Description
Pressure sensor, pressure sensor arrangement and use of the pressure sensor Technical field
[0001] The invention relates to a pressure sensor, a pressure sensor assembly comprising a pressure sensor and a mounting body, and the use of the pressure sensor or pressure sensor assembly, particularly in connection with measuring the pressure of hydrogen. State of the art
[0002] From EP1146326A2, a pressure sensor with the features of the preamble of claim 1 is known. The known pressure sensor is arranged in a bore of a mounting body, which communicates with a supply bore under pressure of a medium, wherein the pressure acts on a diaphragm arranged in a chamber of a sensor housing of the pressure sensor. The diaphragm is in turn operatively connected to a measuring or sensor element arranged inside the sensor housing, which detects a deformation of the diaphragm in order to deduce the level of pressure of the medium. In one embodiment of the pressure sensor or the pressure sensor arrangement, it can be provided that the pressure sensor is connected to the bore with the axial interposition of a separate sealing element, which is conical in sections, in such a way that the sealing element seals the bore orof the pressure sensor in order to prevent any leakage of medium from the mounting body.O. W 32 4 K The membrane is arranged in an approximately central area with respect to the axial extension of the sensor housing, i.e. the medium must first pass through the sensor housing into the chamber in order to act on the membrane.
[0003] If the medium contains hydrogen, the pressure sensor must be both impermeable and resistant to hydrogen. This is because, if the sensor housing and membrane are made of metallic material, hydrogen can penetrate the material and cause corrosion, resulting in hydrogen-induced cracking, brittle fracture, and failure of the pressure sensor. The penetrated hydrogen can also react chemically with the measuring or sensor element located inside the sensor housing and impair the functionality of the sensor element. Disclosure of the Invention
[0004] The pressure sensor according to the invention with the features of claim 1 has a sensor housing which, considering its axial length, is particularly compact, which makes it possible to measure the pressure of a medium directly or in a region of the bore of the mounting body which is close to a supply section for the medium. The bore is as short as possible in its axial extent. The sensor housing has a front end in the region of the bore, which front end forms a diaphragm. This enables very precise pressure measurement. This is because with increasing length of the bore, the pressure in the bore changes, which distorts the pressure measurement. It is also not necessary to provide a supply of the medium within the sensor housing. W 32 4 K The medium can be provided in the form of a bore or chamber up to the membrane area. Instead, the interior of the sensor housing can serve solely to accommodate the measuring or sensor element.
[0005] To achieve the aforementioned advantages, the invention provides that the sealing element is arranged at a distance from the front end in the region of the sensor housing where the sensor housing protrudes from the receiving body and into the bore. In contrast to the prior art, the pressure sensor is sealed in the bore before the medium can reach the receiving body. Especially with a medium that contains hydrogen, the hydrogen cannot then reach the receiving body at all. The receiving body therefore does not have to be made of a material that is resistant to hydrogen, which makes the production of the pressure sensor cost-effective. In the following, a medium that contains hydrogen is understood to mean a hydrogen-containing fluid medium that contains at least one percent hydrogen by volume.
[0006] Advantageous further developments of the pressure sensor according to the invention are listed in the subclaims.
[0007] In a preferred development of the pressure sensor, the sensor housing has a conical sensor housing section in a region facing away from the end face in the direction of the receiving body; which sealing element is arranged in the conical sensor housing section.
[0008] The pressure sensor is sealed in the hole between the sensor housing and the mounting body. W 32 4 K Thus, a medium containing hydrogen only reaches the front end and the conical sensor housing section of the sensor housing.
[0009] In a further preferred development of the pressure sensor, the sensor housing is formed in one piece from the front side up to and including the conical sensor housing section.
[0010] The area of the sensor housing that comes into contact with a medium containing hydrogen is manufactured in one piece, which is cost-effective and eliminates the need for a material bond such as a weld seam that comes into contact with the medium containing hydrogen, which could cause premature deterioration. Thus, the front end up to and including the conical sensor housing section is constructed in one piece.
[0011] In a first preferred embodiment of the pressure sensor, in which, in contrast to the aforementioned prior art, a separate sealing element can be dispensed with, the sealing element is formed by a conical section that is monolithic with the sensor housing. This results in a particularly simple pressure sensor structure that requires few components, which is cost-effective.
[0012] Alternatively, it can also be provided that the sealing element is formed by a component separate from the sensor housing, which is connected to the sensor housing by a conical form-fitting connection. The use of a sealing element separate from the sensor housing W 32 4 K enables optimal adaptation of the materials of the sealing element and the sensor housing to the respective application and thus, on the one hand, an optimized sealing effect of the sealing element, and on the other hand, for example, the use of a material that is particularly easy and cost-effective to process for the production of the sensor housing.
[0013] In a preferred development of the last proposal, it is provided that the sealing element is annular and the sensor housing has a conical receptacle for positioning the sealing element, wherein the receptacle forms a stop surface for the sealing element counter to a mounting direction of the pressure sensor in the bore of the mounting body, and wherein the sealing element and the sensor housing consist of the same or different materials.
[0014] In particular, in connection with the same or not significantly different thermal expansion coefficients of the sensor housing, the receiving body and the mounting body, it can be provided that the sensor housing is directly connected to the receiving body.
[0015] However, to compensate for different thermal expansion coefficients of the components in question, it can also be provided that the sensor housing is connected to the receiving body with the interposition of a preferably annular heat compensation element, wherein the material of the sensor housing and the material of the receiving body have different thermal expansion coefficients. O W 32 4 K
[0016] The fastening of the receiving body in the mounting body preferably involves an implementation in which the fastening area on the receiving body is designed in the form of an external thread on the receiving body. This external thread interacts with a matching internal thread in the bore of the mounting body, whereby the required sealing force for sealing the receiving body or the sensor housing is applied by screwing the receiving body into the bore or the internal thread of the mounting body.
[0017] A further preferred structural design of the sensor housing with a view to achieving the highest possible sensitivity of the measuring element provides that the sensor housing is designed rotationally symmetrical to a longitudinal axis, and that the membrane has a ring-shaped weakened region radially outside a connection region with the measuring element, in the region of which the wall thickness of the membrane is reduced compared to the connection region.
[0018] To enable the simplest and most reproducible way of mounting the receiving body or the pressure sensor in the mounting body with regard to generating the sealing force, it is also provided that the receiving body has a tool engagement surface for connecting the pressure sensor to the mounting body. This makes it possible, when using a threaded connection, to generate the required sealing force via a defined tightening torque of the receiving body in the bore of the mounting body. O W 32 4 K
[0019] Furthermore, the invention also includes a pressure sensor arrangement with a pressure sensor according to the invention as described so far and a mounting body with a bore for fastening the receiving body of the pressure sensor.
[0020] In a preferred structural embodiment of the pressure sensor arrangement for achieving the desired sealing force, it is provided that the bore has a feed section for the medium, which on the side facing the pressure sensor merges into a conical mounting body section, and that the conical mounting body section has a first opening angle which is greater than a second opening angle of the sensor housing or the sealing element in a contact zone between the bore in the mounting body and the sensor housing or the sealing element.
[0021] In a further development of the geometry described above, the sealing element is positioned in the transition area between the supply section and the conical mounting body section in the area of the annular contact zone against the bore. This ensures that the aforementioned elements are always positioned in the same location, regardless of the tolerances of the two opening angles in the area of the bore and the sensor housing or the sealing element.
[0022] Finally, the invention also encompasses the use of a pressure sensor according to the invention or a corresponding pressure sensor arrangement for detecting a pressure of hydrogen. O W 32 4 K Short description of the drawings
[0023] Further advantages, features and details of the invention emerge from the following description of preferred embodiments of the invention and from the drawings. Fig. 1 shows a longitudinal section in the area of a pressure sensor arrangement for measuring the pressure of hydrogen; Fig. 2 shows a detail of Fig. 1 in an enlarged view; Fig. 3 shows an end region of a sensor housing of the pressure sensor of Figs. 1 and 2 in a longitudinal section; Fig. 4 shows a sensor housing modified compared to Fig. 3, also in a longitudinal section; and Fig. 5 shows a pressure sensor modified compared to the illustration in Figs. 1 and 2 for compensating for different thermal expansion coefficients of the components of the pressure sensor arrangement in a longitudinal section.
[0024] Identical elements or elements with the same function are provided with the same reference numerals in the figures. O W 32 4 K Embodiments of the invention
[0025] Fig. 1 shows a pressure sensor arrangement 100 for measuring the pressure of an exemplary gaseous medium, in particular hydrogen. The pressure sensor arrangement 100 comprises a mounting body 102 with a multi-stepped bore 104 for receiving a pressure sensor 10. The bore 104 has a longitudinal axis 105. The bore 104 extends along the longitudinal axis 105 and has a (cylindrical) supply section 106 in which the pressure of the medium (hydrogen) acts. Adjoining the supply section 106 is a conical mounting body section 107, which has a first opening angle α1. The conical mounting body section 107 merges via a base section 108 extending perpendicular to the longitudinal axis 105 into a threaded section 109 of the mounting body 102, in the area of which an internal thread 110 is formed.
[0026] The pressure sensor 10 has a receiving body 12 arranged concentrically to the longitudinal axis 105, which has a cylindrical portion 14 with an external thread 16 as a mounting portion, which cooperates with the internal thread 110 of the threaded portion 109 to secure the receiving body 12 within the bore 104 of the mounting body 102. Outside the cylindrical portion 14 or outside the bore 104, the receiving body 12 has a mounting portion 18 of enlarged diameter, which has a tool engagement surface 20 on its outer surface for interacting with a tool (not shown), in particular with an open-end wrench or a torque wrench. W 32 4 K The receiving body 12 and thus the pressure sensor 10 can be screwed or fastened in the bore 104 of the mounting body 102 via the tool engagement surface 20.
[0027] Concentric to the longitudinal axis 105, the receiving body 12 also has a through-bore 22 with a first section 24 and, on the side facing away from the mounting section 18, a second section 26 which is larger in diameter than the first section 24. The through-bore 22 serves to accommodate a sensor housing 30 which, as shown in Figs. 1 to 3, protrudes partially from the receiving body 12 along the longitudinal axis 105 and projects with a front end region 32 into the feed section 106 of the bore 104. The front end region 32 forms an end of the sensor housing 30 facing away from the receiving body 12 and ends in an end face 34 of the sensor housing 30. The front end region 32 forms a membrane 36 (Fig. 2). In an area facing away from the end face 34 in the direction of the receiving body 12, the sensor housing 30 merges into a first hollow cylindrical section 38 (Fig.2), which in turn merges into a conical sensor housing section 40 (Fig. 2). The sensor housing 30; 30a; 30b is formed in one piece from the end face 34 to the conical sensor housing section 40; 40a. The conical sensor housing section 40 has a second opening angle α2 on its outer side, wherein the second opening angle α2 is smaller than a first opening angle α1 (Fig. 2) on the conical mounting body section 107 of the bore 104. For example, the second opening angle α2 is at least 1° smaller than the first opening angle α1. O. W 32 4 K
[0028] The conical sensor housing section 40 in turn merges in the direction of the receiving body 12 into a second hollow cylindrical section 42 (Fig. 3) of the sensor housing 30. Continuing in the direction of the receiving body 12, the second hollow cylindrical section 42 merges into a hollow cylindrical sensor housing section 44 (Fig. 1) which is again enlarged in diameter and is designed to penetrate into the second section 26 of the through-bore 22 of the receiving body 12 and acts as a stop surface 64 for the sensor housing 30 in the direction of the receiving body 12. The sensor housing 30; 30a; 30b has a hollow cylindrical section 42 which extends from the conical sensor housing section 40; 40a facing away from the receiving body 12 has a material connection 43 with the hollow cylindrical sensor housing section 44.Thus, the second hollow cylindrical section 42 and the hollow cylindrical sensor housing section 44 are mechanically connected to one another via a material-locking connection 43 such as a weld seam.
[0029] As is particularly evident from Figs. 2 and 3, the membrane 36 has a central connection area 46 for attaching a measuring element 48, in particular in the form of a piezoelectric element 50. The piezoelectric element 50 can operate according to the piezoresistive or piezoelectric measuring principle. The measuring element 48 or the piezoelectric element 50 is connected to the membrane 36 in a manner known per se, such that a deformation of the membrane 36 leads to the generation of a corresponding signal at the measuring element 48. W 32 4 K
[0030] Radially outside the connection area 46 between the measuring element 48 and the membrane 36, the membrane 36 has an elastic area 52 which runs in a ring shape around the longitudinal axis 105 and in which area the wall thickness of the membrane 36 is reduced when viewed from the side of a chamber 54 which serves as a receiving space for the measuring element 48.
[0031] In order to arrange the pressure sensor 10 in the bore 104 of the mounting body 102 in a sealing manner, in order to thereby prevent the medium from escaping from the mounting body 102, a mounting force F directed in the direction of the supply bore 106 is generated via the receiving body 12 and the threaded connection between the receiving body 12 and the mounting body 102. The mounting force F causes the sensor housing 30 with its conical sensor housing section 40 to bear sealingly against a contact zone 56 extending annularly around the longitudinal axis 105 in the transition area between the supply bore 106 and the conical mounting body section 107. With respect to the longitudinal axis 105, the contact zone 56 lies in front of the receiving body 12, so that the medium cannot reach the receiving body 12. The sensor housing 30 thus simultaneously forms a sealing element 60 in the region of its conical sensor housing section 40.
[0032] Instead of a sealing element 60 formed monolithically by the conical sensor housing section 40, it can also be provided, as shown in Fig. 4, to use a modified sensor housing 30a which has a conical receptacle 62 in the conical sensor housing section 40a which runs annularly around the longitudinal axis 105 and which has a perpendicular to the longitudinal axis 105O W 32 4 K Has a stop surface 64. The conical receptacle 62 serves to positively accommodate a sealing element 60a, which is designed as a separate component in the form of a sealing ring 66 and is made of the same or a different material. The use of a sealing element 60a made of the same material as the sensor housing 30a avoids different thermal expansion coefficients in the area of the contact zone 56. The use of a sealing element 60a made of a softer material than the sensor housing 30a has the advantage that only a comparatively low tightening torque is required to seal the contact zone 56, which increases the service life of the pressure sensor 10 because it is thus only exposed to a low tightening torque for sealing.Because the sealing element 60a interacts with the stop surface 64 in the axial direction opposite to the mounting direction of the receiving body 12 into the bore 104 of the mounting body 102, the required sealing force in the region of the bore 104 is also generated via the sensor housing 30a. Analogous to the conical sensor housing section 40a, the sealing element 60a or the sealing ring 66 also has a conical, circumferential outer surface 68 with the second opening angle α2 as a sealing surface. The value of the second opening angle α2 in the exemplary embodiment according to Fig. 4 can differ from the value of the second opening angle α2 in the exemplary embodiment according to Fig. 3. In the embodiment of the pressure sensor 10 according to Fig. 4, the contact zone 56 is also located in front of the receiving body 12 with respect to the longitudinal axis 105, so that the medium cannot reach the receiving body 12.
[0033] In the embodiment of the pressure sensor 10 shown in Figs. 1 to 4, the sensor housing 30,O W 32 4 K 30a is connected directly to the receiving body 12. This is always advantageous when the materials of the receiving body 12, the sensor housing 30, 30a, and the mounting body 102 have at least approximately the same thermal expansion coefficients, which differ from one another by no more than 10%, for example. In order to ensure the required tightness under all operating conditions or pressures and temperatures, even with thermal expansion coefficients that differ significantly from one another, it can also be provided, as shown in Fig. 5, to connect a sensor housing 30b to the receiving body 12 with the radial interposition of an annular heat compensation element 70. For this purpose, the heat compensation element 70 has, for example, an internal thread 72 that interacts with an external thread 74 formed on the sensor housing 30b.It is advantageous if the directions of the external thread 72 on the heat compensation element 70 and on the external thread 16 of the receiving body 12 run in different directions in order to prevent the heat compensation element 70 from becoming loose in the receiving body 12 when the receiving body 12 is screwed into the threaded section 109 of the mounting body 102.
[0034] The pressure sensor 10 or the pressure sensor arrangement 100 described so far can be modified in a variety of ways without deviating from the inventive concept. O W 32 4 K Reference numeral 10 pressure sensor 12 receiving body 14 cylindrical section 16 external thread 18 mounting section 20 tool engagement surface 22 through-hole 24 first section 26 second section 30 sensor housing 30a, 30b sensor housing 32 front end 34 front side 36 membrane 38 first hollow cylindrical section 40, 40a conical sensor housing section 42 second hollow cylindrical section 43 material connection 44 hollow cylindrical sensor housing section 46 connecting area 48 measuring element 50 piezo element 52 elastic area 54 chamber 56 contact zone 60, 60a sealing element 62 receiving element 64 stop surface O W 32 4 K 66 Sealing ring 68 Outer surface 70 Heat compensation element 72 Internal thread 74 External thread 100 Pressure sensor assembly 102 Mounting body 104 Bore 105 Longitudinal axis 106 Feed section 107 Conical mounting body section 108 Base section 109 Threaded section 110 Internal thread F Mounting force α11. Opening angle α22. Opening angle O W 32 4 K
Claims
Claim 1. Pressure sensor (10), comprising a receiving body (12) for receiving a sensor housing (30; 30a; 30b), wherein the sensor housing (30; 30a; 30b) has a chamber (54) for receiving a measuring element (48), the sensor housing (30; 30a; 30b) having a diaphragm (36), the measuring element (48) being arranged in operative connection with the diaphragm (36) for measuring the pressure of a medium in order to detect a pressure-dependent deformation of the diaphragm (36), wherein the receiving body (12) can be inserted into a bore (104) of a mounting body (102) by means of a mounting section (16), wherein the sensor housing (30; 30a; 30b) is extended out of the receiving body (12) and into the bore (104) in the region of the bore (104) with respect to a longitudinal axis (105) of the bore (104). protrudes into which sensor housing (30; 30a; 30b) has an end face (32) in the area of the bore (104), which end face (32) forms the membrane (36), and with a sealing element (60;60a) for sealing the sensor housing (30; 30a; 30b) in the bore (104), wherein the sealing element (60; 60a) is conically shaped at least partially on its outer side, characterized in that the sealing element (60; 60a) is arranged at a distance from the end face (32) in the area of the sensor housing (30; 30a; 30b) where the sensor housing (30; 30a; 30b) projects out of the receiving body (12) and into the bore (104).
2. Pressure sensor according to claim 1, characterized in that the sensor housing (30; 30a; 30b) is arranged in a region of the receiving body (12) where the sensor housing (30; 30a; 30b) projects out of the receiving body (12) and into the bore (104). W 32 4 K 3. Pressure sensor according to claim 2, characterized in that the sensor housing (30; 30a; 30b) has a conical sensor housing section (40; 40a) in a region facing away from the end face (34) in the direction towards the receiving body (12); and that the sealing element (60; 60a) is arranged in the conical sensor housing section (40; 40a).
4. Pressure sensor according to claim 2 or 3, characterized in that the sensor housing (30; 30a; 30b) has a material-bonded connection (43) with a hollow cylindrical sensor housing section (44) in a region facing away from the conical sensor housing section (40; 40a) in the direction towards the receiving body (12).
5. Pressure sensor according to one of claims 2 to 4, characterized in that the sealing element (60) is formed monolithically with the conical sensor housing section (40). 6.Pressure sensor according to one of claims 1 to 4, characterized in that the sealing element (60a) is formed by a component separate from the sensor housing (30a), which is connected to the sensor housing (30a) by a conical positive-locking connection.
7. Pressure sensor according to claim 6, characterized in that the sealing element (60a) is designed in the form of a sealing ring (66) and the sensor housing (30a) has a conical O. W 32 4 K Receptacle (62) for positioning the sealing element (60a), wherein the receptacle (62) forms a stop surface (64) for the sealing element (60a), and wherein the sealing element (60a) and the sensor housing (30a) are made of the same or different materials.
8. Pressure sensor according to any one of claims 1 to 7, characterized in that the sensor housing (30; 30a) is directly connected to the receiving body (12).
9. Pressure sensor according to any one of claims 1 to 7, characterized in that the sensor housing (30b) is connected to the receiving body (12) via an interposed, preferably annular, heat-compensating element (70), wherein the material of the sensor housing (30b) and the material of the receiving body (12) have different coefficients of thermal expansion. 10.Pressure sensor according to any one of claims 1 to 9, characterized in that the receiving body (12) has a tool engagement surface (20) for connecting the pressure sensor (10) to the mounting body (102).
11. Pressure sensor arrangement (100), comprising a pressure sensor (10) configured according to any one of claims 1 to 10 and a mounting body (102) with a bore (104) for fastening the receiving body (12) of the pressure sensor (10).
12. Pressure sensor arrangement according to claim 1, characterized in that the bore (104) has a feed section (106) for the medium, which on the side facing the pressure sensor (10) is conically shaped. W 32 4 K The mounting body section (107) transitions into the conical mounting body section (107), and the conical mounting body section (107) has a first opening angle (α1) that is larger than a second opening angle (α2) of the sensor housing (30; 30b) or the sealing element (60a) in a contact zone (56) between the bore (104) in the mounting body (102) and the sensor housing (30; 30b) or the sealing element (60a).
13. Pressure sensor arrangement according to claim 12, characterized in that the sealing element (60; 60a) bears against the bore (104) in the transition area between the feed section (106) and the conical mounting body section (107) in the region of the annular contact zone (56).
14. Use of a pressure sensor (10) configured according to any one of claims 1 to 10 and / or a pressure sensor arrangement (100) according to any one of claims 11 to 13 for measuring the pressure of hydrogen. W 32 4 K