Sensor for detecting an h2 free in a measuring gas in a measuring gas chamber

Abstract

The invention relates to a sensor (10) for detecting an H2 fraction in a measurement gas in a measurement gas chamber (12). The sensor (10) comprises: at least one sensor element (14) which is designed to detect an H2 portion and to output a measurement signal indicating the H2 portion; an inlet element (18) which defines an interior space (20) and has an inlet opening (22), the inlet opening (22) being configured for a portion of the measurement gas to enter the interior space (20) from the measurement gas chamber (12), the sensor element (14) being fluidically connected to the interior space (20); and a cover (30), the cover (30) being arranged on the access element (18) and partially covering the access opening (22).

Description

Technical Field

[0001] A sensor for detecting the H2 fraction in a measurement gas in a measurement gas chamber, comprising: at least one sensor element, which is configured to detect the H2 fraction and output a measurement signal indicating the H2 fraction; an entry element, which defines an interior space and has an entry opening, wherein the entry opening is configured to allow a portion of the measurement gas to enter the interior space from the measurement gas chamber, wherein the sensor element is fluidically connected to the interior space; and a cover, wherein the cover is arranged on the entry element and partially covers the entry opening. Background Art

[0002] A large number of sensors, sensor elements and methods for detecting the H 2 proportion in a measurement gas in a measurement gas chamber are known from the prior art.

[0003] Sensor elements of the type described here can be used in a variety of fields, such as automotive technology, process engineering, chemistry and mechanical engineering. Therefore, determining the hydrogen concentration (for example in an air-hydrogen mixture) plays an important role, for example in the application of hydrogen fuel cell systems. Safety-related applications should also be mentioned here. An air-hydrogen mixture becomes combustible, for example, with a hydrogen content of 4%. Sensor elements for detecting hydrogen are used, for example, in hydrogen fuel cell vehicles in order to detect hydrogen escaping due to damage or defects, for example, and to trigger warning signals and / or protective measures by coupling to the corresponding system. Therefore, each fuel cell vehicle requires a plurality of hydrogen sensors, which are either installed in the exhaust system (exhaust) or operate under atmospheric conditions (ambient).

[0004] A variety of measuring principles can be used for such hydrogen sensors, including in particular the following measuring principles: thermal conductivity, catalytic combustion heat sensor, electrochemical cell, semiconducting metal oxide, chemiresistor, field effect transistor.

[0005] Despite the advantages of the hydrogen sensors known from the prior art, they still have the potential for improvement. Thus, they usually have a membrane with a mounting receptacle or a touch protection device. However, they do not have further measures for protecting the medium contact from external influences. Summary of the invention

[0006] Therefore, within the scope of the present invention, a sensor for detecting the H2 fraction in a measuring gas in a measuring gas chamber is proposed, which sensor at least largely avoids the disadvantages of known sensors for detecting the H2 fraction in a measuring gas and provides sufficient protection for the sensor element from external influences that could have a negative impact on the measurement accuracy.

[0007] The sensor according to the invention for detecting at least one property of an H 2 portion in a measured gas in a measured gas chamber comprises at least one sensor element which is designed to detect the H 2 portion and to output a measurement signal which is indicative of the H 2 portion.

[0008] In principle, the measured gas chamber can be any open or closed space in which the measured gas is received and / or flows through. For example, the measured gas chamber can be the engine compartment, the trunk, the driver's cabin or the hydrogen line of a fuel cell vehicle.

[0009] In the context of the present invention, a sensor element is understood in principle to be any device that can detect the hydrogen content in the measured gas and that can, for example, generate at least one measurement signal, such as an electrical measurement signal (e.g., voltage or current), based on the detected hydrogen content. In addition, other characteristics and / or characteristic combinations may also be detectable. The sensor element may be configured in particular for use in a hydrogen fuel cell vehicle. The sensor element may be a micro-electromechanical sensor element in particular. This may be based in particular on a thermal measurement principle that detects the thermal conductivity of the measured gas.

[0010] The sensor further comprises an inlet element. The inlet element defines an interior space and has an inlet opening. The inlet opening is configured to allow a portion of the measured gas from the measured gas chamber to enter the interior space. The sensor element is fluidically connected to the interior space.

[0011] In principle, an inlet element can be understood as any element or component which can conduct measured gas from the measured gas chamber to the sensor element in a targeted manner. Thus, the inlet element is particularly suitable for discharging a predetermined portion of measured gas from the measured gas chamber and conducting it to its interior, from which the measured gas can contact the sensor element.

[0012] The sensor further comprises a cover which is arranged on the access element and partially covers the access opening.

[0013] In principle, a cover can be understood as any element or component that can partially cover the access opening in order to thereby make it difficult for liquid and / or solid matter to reach the interior space and thus protect the sensor element from such external influences. The protective effect is based on a reduction in the cross section of the access opening.

[0014] By providing a cover in the sensor according to the invention, it is possible to avoid damage, destruction and erroneous measurements, in particular failure to detect the hydrogen concentration, by protecting the microelectromechanical sensor element from external influences. External influences can be foreign matter (e.g. dust, particles, stone chips, insects) or liquid water (e.g. spray water, jet water, surge water, high-pressure cleaning water) or frozen water (e.g. ice, hail, flying snow) or operating errors and touch.

[0015] The cover can be designed to cause at least one deflection of the measured gas when it enters the interior space. In this way, a centrifugal deflection is achieved, wherein only light particles and gases can reach the sensor element along the entry path, while heavier particles cannot.

[0016] The cover can define an inlet channel with an inlet channel axis, which opens into the interior space. The inlet channel can have an inlet channel inlet opening and an inlet channel outlet opening, which opens into the interior space, laterally relative to the inlet channel axis. The inlet channel outlet opening can be oriented at an angle of 60° to 90° relative to the inlet channel inlet opening. In this way, a deflection of the measured gas and its entrained components can be achieved in a particularly simple manner and a direct access to the sensor element can be prevented.

[0017] The cover may have an end face partially covering the inlet opening. The end face may be inclined at a first predetermined angle away from the interior space and towards the inlet opening of the inlet channel. Thus, by optimizing the outflow geometry, in particular by the inclination angle of the surface relative to the horizontal plane, water is prevented from accumulating in the interior space.

[0018] The first predetermined angle may be 3.0° to 20.0° and preferably 4.0° to 15.0°.Thus, by optimizing the outflow geometry, in particular by an inclination angle of 5° or more of the surface relative to the horizontal, water is prevented from accumulating in the interior space.

[0019] The end face can have at least one drip edge or drip nose, especially wavy drip nose.In order to guide water out from the inner space, a drip edge (similar to a windowsill) or a serrated or wavy drip nose (similar to a sunshade) is particularly advantageous.

[0020] The inlet channel may have an inlet channel side wall and an inlet channel end wall which delimit a lateral inlet channel outlet opening. The inlet channel end wall may close the inlet channel in an axial direction relative to the inlet channel axis. The inlet channel end wall may be inclined toward the inlet channel outlet opening at a second predetermined angle relative to the inlet channel axis. Thus, by optimizing the outflow geometry, in particular by the inclination angle of the surface relative to the horizontal plane, water is prevented from accumulating in the interior space.

[0021] The second predetermined angle may be 3.0° to 20.0° and preferably 4.0° to 15.0°.Thus, by optimizing the outflow geometry, in particular by an inclination angle of 5° or more of the surface relative to the horizontal, water is prevented from accumulating in the interior space.

[0022] The entry channel end wall can have at least one drip edge or drip nose, especially wavy drip nose.In order to guide water out from the inner space, a drip edge (similar to a windowsill) or a serrated or wavy drip nose (similar to a sunshade) are particularly advantageous.

[0023] The first distance between the entry channel end wall and the side wall of the entry element as viewed in the radial direction relative to the entry channel axis, the second distance between the entry channel end wall and the side wall of the entry element as viewed in the axial direction relative to the entry channel axis, the third distance between the entry channel end wall and the end face as viewed in the axial direction relative to the entry channel axis, and / or the fourth distance between the entry channel side wall and the end face as viewed in the radial direction relative to the entry channel axis can be at least 4.0 mm and preferably at least 5.0 mm. Capillary effects can thereby be reliably prevented.

[0024] A grid may be arranged between the end wall of the entry channel and the end face, viewed in the axial direction relative to the entry channel axis, between the side wall of the entry channel and the end face, viewed in the radial direction relative to the entry channel axis, between the end wall of the entry channel and the side wall of the entry element, and / or between the opposite side walls of the entry element. In addition to the protection provided by the cover, a grid, in particular a fine mesh grid, may be added to protect against insects and / or to minimize condensation. Advantageously, the mesh size is 0.25 mm to 2 mm, and preferably 0.5 mm to 1 mm, for example 0.5 mm. The grid may be made of a corrosion-resistant metal, such as stainless steel, or a corrosion-resistant metal, such as a plastic-coated steel mesh.

[0025] A membrane may be arranged between the sensor element and the interior. Such a membrane serves to delicately protect the underlying sensor element, in particular from water drops, dust and fine particles.

[0026] In the context of the present invention, a membrane is understood to be a thin structure which, like a skin or a film, has a large surface extension relative to its thickness. Advantageous materials are made of, for example, PET fabric, with or without a carrier material, for example of polyester fleece. The purpose of the membrane is to be permanently impermeable to water, even after contact with coolants, cleaning agents and moist dust.

[0027] The membrane may be hydrogen permeable to allow hydrogen from the interior space to pass through to the sensor element.

[0028] The membrane may be made at least partially of a hydrophobic and oleophobic material.

[0029] A sealing element can be arranged between the diaphragm and the sensor element. The seal consists of the base polymer EPDM. The sealing element has the function of protecting the electronics chamber from water ingress. When using the diaphragm proposed here, the installation of the sealing element is not absolutely necessary. Nevertheless, a seal is used here because, for manufacturing reasons, the hydrogen ambient sensor (ambient) should use the same construction and connection technology as the hydrogen exhaust sensor (exhaust).

[0030] The cover can be made of plastic. Plastic causes minimization of condensation. The cover can be made of conductive plastic. For example, the cover can be made of glass fiber reinforced polybutylene terephthalate PBT-GF and can have a connection to ground or another potential in order to reduce or avoid sensor contamination caused by electric fields. Alternatively or additionally, the cover can have an antistatic coating. Thereby, sensor contamination caused by electric fields can be reduced or avoided. Alternatively or additionally, the cover can have a hydrophobic coating or be made of a hydrophobic material. Thereby, adhesion and accumulation of water can be avoided.

[0031] The cover can be connected to the access element in a releasable or non-releasable manner, in particular by clamping, gluing or welding.

[0032] The invention can be demonstrated on the product by external observation or by material analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further optional details and features of the invention emerge from the following description of preferred exemplary embodiments which are schematically illustrated in the drawings.

[0034] It shows:

[0035] Figure 1 A cross-sectional view of a sensor according to one embodiment of the present invention;

[0036] Figure 2 A bottom view of the sensor;

[0037] Figure 3 a bottom view of the sensor with the cover removed;

[0038] Figure 4 A cross-sectional view of a sensor according to another embodiment of the present invention;

[0039] Figure 5 a cross-sectional view of a sensor according to another embodiment of the present invention; and

[0040] Figures 6A to 6D Cross-sectional view of a sensor according to a further embodiment of the present invention. DETAILED DESCRIPTION

[0041] Figure 1 1 is a cross-sectional view of a sensor 10 according to an embodiment of the present invention. The sensor 10 is configured to detect the H2 content in the measurement gas in the measurement gas chamber 12. In particular, the sensor 10 can be configured to be used in a hydrogen fuel cell vehicle. However, other applications are also feasible. In particular, the sensor 10 can include one or more additional functional elements, such as electrodes, electrode leads and contacts, multiple layers or other elements, which are not presented in detail in the drawings. Correspondingly, the sensor 10 can be placed in the exhaust system (exhaust) of a hydrogen fuel cell vehicle or also work under atmospheric conditions (ambient). Therefore, the measuring chamber can be the interior space of the exhaust system or a hydrogen fuel cell vehicle.

[0042] The sensor 10 has at least one sensor element 14 . The sensor element 14 is designed to detect the H2 component and to output a measurement signal indicating the H2 component. The sensor element 14 is arranged on a printed circuit board 16 or is connected thereto.

[0043] The sensor 10 has an inlet element 18. The inlet element 18 defines an interior space 20. The inlet element 18 has an inlet opening 22. The inlet opening 22 is configured to allow a portion of the measured gas from the measured gas chamber 12 to enter the interior space 20. The inlet element is configured to be essentially rotationally symmetrical, for example cylindrical. The sensor element 14 is fluidically connected to the interior space 20.

[0044] A diaphragm 24 is arranged between the interior space 20 and the sensor element 14. Preferably, the diaphragm 24 is at least partially made of a hydrophobic and oleophobic material. The diaphragm 24 is permeable to hydrogen. Furthermore, a sealing element 26 is arranged between the diaphragm 24 and the sensor element 14. The sealing element 26 has an opening 28 through which hydrogen can reach the sensor element 14.

[0045] The sensor 10 also has a cover 30. The cover 30 can be made of plastic to minimize condensation. The cover 30 can be made of conductive plastic, such as glass-fiber reinforced polybutylene terephthalate PBT-GF, and have a connection to ground or another potential in order to reduce or avoid sensor contamination caused by electric fields. Alternatively or additionally, the cover 30 can be provided with an antistatic coating in order to reduce or avoid sensor contamination caused by electric fields. Alternatively or additionally, the cover 30 can be provided with a hydrophobic coating or made of a hydrophobic material in order to avoid the adhesion and accumulation of water. In particular, the cover 30 can be configured in a cap-shaped manner or as a cover.

[0046] Figure 2 A bottom view of the sensor 10 is shown. Figure 3The sensor 10 is shown in a bottom view with the cover 30 removed. The cover 30 is arranged on the access element 18 and partially covers the access opening 22. The cover 30 can be connected to the access element 18 in a releasable or non-releasable manner, for example by clamping, gluing or welding. Figure 2 and Figure 3 Together, it can be seen that cover 30 provides, in particular, contact protection for diaphragm 24 or sensor element 14 located underneath.

[0047] The cover 30 is designed to cause at least one deflection of the measured gas when entering the interior space 20. In particular, the cover 30 defines an inlet channel 32 with an inlet channel axis 34, which opens into the interior space 20. The inlet channel 32 has an inlet channel inlet opening 36 and an inlet channel outlet opening 38, which opens into the interior space 20, lateral to the inlet channel axis 34. The inlet channel outlet opening 38 is oriented at an angle α of 60° to 90° (e.g. 90°) relative to the inlet channel inlet opening 36. In the embodiment shown, the inlet channel inlet opening 36 is oriented parallel to the inlet opening 22. An orientation of the inlet channel inlet opening 36 that deviates from this is also possible in principle.

[0048] The cover 30 has an end surface 40 partially covering the access opening 22. The end surface 40 is inclined at a first predetermined angle β away from the interior space 20 and toward the access passage access opening 36. The first predetermined angle β is preferably 3.0° to 20.0° and preferably 4.0° to 15.0°, for example 5.0°.

[0049] The inlet channel 32 has an inlet channel side wall 42 and an inlet channel end wall 44 which bounds a lateral inlet channel outlet opening 38. The inlet channel end wall 44 closes the inlet channel 32 in an axial direction relative to the inlet channel axis 34. The inlet channel end wall 44 is inclined toward the inlet channel outlet opening 38 at a second predetermined angle γ relative to the inlet channel axis 34. The second predetermined angle γ is 3.0° to 20.0° and preferably 4.0° to 15.0°, for example 5.0°.

[0050] A first distance 46 between the entry channel end wall 44 and the side wall 48 of the entry element 18, viewed in the radial direction relative to the entry channel axis 34, is at least 4.0 mm and preferably at least 5.0 mm. A second distance 50 between the entry channel end wall 44 and the side wall 48 of the entry element 18, viewed in the axial direction relative to the entry channel axis 34, is at least 4.0 mm and preferably at least 5.0 mm. Here, the second distance 50, viewed in the axial direction, is measured between the point of the entry channel end wall 44, which is furthest from the side wall 48 of the entry element 18, viewed in the axial direction, and the side wall 48 of the entry element 18. A third distance 52 between the entry channel end wall 44 and the end face 40, viewed in the axial direction relative to the entry channel axis 34, is at least 4.0 mm and preferably at least 5.0 mm. Here, the third distance 52, viewed in the axial direction, is measured between the point of the entry channel end wall 44, which is closest to the end face 40, viewed in the axial direction, and the end face 40. A fourth distance 54 between the inlet channel side wall 42 and the end face 40 , viewed in a radial direction relative to the inlet channel axis 34 , is at least 4.0 mm and preferably at least 5.0 mm.

[0051] By providing the cover 30, the measured gas passes from the measured gas chamber 12 through the inlet channel inlet opening 36 into the inlet channel 32 and is then deflected in the region of the lateral inlet channel outlet opening 38 and thus into the interior 20 in the inlet element 18, as indicated by the arrow 56 representing the gas path. The measured gas then passes from the interior 20 via the diaphragm 24 and the sealing element 26 to the sensor element 14, as further indicated by the arrow 56.

[0052] Figure 4 FIG. 1 is a cross-sectional view of a sensor 10 according to another embodiment of the present invention. Figures 1 to 3 The differences between the embodiments shown in FIG. 4 and identical or similar components are provided with the same reference numerals. The end face 40 can have at least one drip edge 58. Alternatively or additionally, the inlet channel end wall 44 can have at least one drip edge 58.

[0053] Figure 5 FIG. 1 is a cross-sectional view of a sensor 10 according to another embodiment of the present invention. Figures 1 to 3 The differences between the embodiments shown in FIG. 4 and identical or similar components are provided with the same reference numerals. The end face 40 may have at least one drip nose 58. Alternatively or additionally, the inlet channel end wall 44 may have at least one drip nose 58. The drip nose 60 may be designed in an undulating manner in particular.

[0054] Figures 6A to 6D FIG. 1 shows a cross-sectional view of a sensor 10 according to another embodiment of the present invention. Figures 1 to 3 Different and identical or similar components of the embodiments shown in FIG. 1 are provided with the same reference numerals.

[0055] exist Fig. 6A In the embodiment shown in FIG, a grille 62 is arranged between the inlet channel end wall 44 and the end face 40 as viewed in the axial direction relative to the inlet channel axis 34. The grille 62 is preferably a fine mesh grille 62 and is configured for insect protection and / or minimization of condensation.

[0056] exist Figure 6B In the embodiment shown in FIG, a grille 62 is arranged between the entry channel side wall 42 and the end face 40 as viewed in a radial direction relative to the entry channel axis 34. The grille 62 is preferably a fine mesh grille 62 and is configured to keep out insects and / or minimize condensation.

[0057] exist Figure 6C In the embodiment shown in FIG, a grille 62 is arranged between the inlet channel end wall 44 and the side wall 48 of the inlet element 18, seen in a radial direction relative to the inlet channel axis 34. The grille 62 is preferably a fine mesh grille 62 and is configured for insect protection and / or minimization of condensation.

[0058] exist Fig.6D In the embodiment shown in FIG, a grille 62 is disposed between opposing side walls of the inlet element 18. The grille 62 is preferably a fine mesh grille 62 and is configured to keep out insects and / or minimize condensation.

Claims

1. A sensor (10) for detecting the H 2 content in a measurement gas in a measurement gas chamber (12), comprising: at least one sensor element (14) which is designed to detect the H2 fraction and to output a measurement signal which is indicative of the H2 fraction, an inlet element (18) which defines an interior space (20) and has an inlet opening (22), wherein the inlet opening (22) is designed to allow a portion of the measured gas to enter from the measured gas chamber (12) into the interior space (20), wherein the sensor element (14) is fluidically connected to the interior space (20), and A cover (30), wherein the cover (30) is arranged on the access element (18) and partially covers the access opening (22).

2. The sensor (10) according to the preceding claim, wherein The cover (30) is designed to cause at least one deflection of the measurement gas when entering the interior space (20).

3. The sensor (10) according to any one of the preceding claims, wherein: The cover (30) defines an inlet channel (32) with an inlet channel axis (34) and opening into the interior space (20), wherein the inlet channel (32) has an inlet channel inlet opening (36) and an inlet channel outlet opening (38) laterally relative to the inlet channel axis (34) and opening into the interior space (20), wherein the inlet channel outlet opening (38) is oriented at an angle (α) of 60° to 90° relative to the inlet channel inlet opening (36).

4. The sensor (10) according to the preceding claim, wherein The cover (30) has an end surface (40) partially covering the entry opening (22), wherein the end surface (40) is inclined away from the interior space (20) and toward the entry channel entry opening (36) at a first predetermined angle (β), wherein the first predetermined angle (β) is preferably 3.0° to 20.0° and preferably 4.0° to 15.0°.

5. The sensor (10) according to any one of claims 3 to 4, wherein: The end face (40) has at least one drip edge (58) or drip nose (60), in particular a corrugated drip nose (60).

6. The sensor (10) according to any one of claims 3 to 5, wherein: The entry channel (32) comprises an entry channel side wall (42) which delimits a lateral entry channel outlet opening (38) and an entry channel end wall (44), wherein the entry channel end wall (44) closes the entry channel (32) in an axial direction relative to the entry channel axis (34), wherein the entry channel end wall (44) is inclined toward the entry channel outlet opening (38) at a second predetermined angle (γ) relative to the entry channel axis (34), wherein the second predetermined angle (γ) is 3.0° to 20.0° and preferably 4.0° to 15.0°.

7. The sensor (10) according to the preceding claim, wherein The inlet channel terminating wall (44) has at least one drip edge (58) or drip nose (60), in particular a corrugated drip nose (60).

8. The sensor (10) according to any one of claims 6 to 7, wherein: A first distance (46) between the entry channel end wall (44) and the side wall (48) of the entry element (18) viewed in a radial direction relative to the entry channel axis (34), a second distance (50) between the entry channel end wall (44) and the side wall (48) of the entry element (18) viewed in an axial direction relative to the entry channel axis (34), a third distance (52) between the entry channel end wall (44) and the end face (40) viewed in an axial direction relative to the entry channel axis (34) and / or a fourth distance (54) between the entry channel side wall (42) and the end face (40) viewed in a radial direction relative to the entry channel axis (34) is at least 4.0 mm and preferably at least 5.0 mm.

9. The sensor (10) according to any one of claims 6 to 8, wherein: A grille (62) is arranged between the entry channel end wall (44) and the end face (40) in the axial direction relative to the entry channel axis (34), between the entry channel side wall (42) and the end face (40) in the radial direction relative to the entry channel axis (34), between the entry channel end wall (44) and the side wall (48) of the entry element (18) in the radial direction relative to the entry channel axis (34), and / or between opposite side walls of the entry element (18).

10. The sensor (10) according to any one of the preceding claims, wherein A membrane (24) is arranged between the sensor element (14) and the interior (20), wherein the membrane (24) is preferably at least partially produced from a hydrophobic and oleophobic material.

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