Device for fail-safe detection of gases in spatial region

Abstract

An apparatus for fail-safe detection of gases within a spatial region is provided. The invention relates to a device for the fail-safe detection of a gas (12) in a spatial region (14), comprising a spacer (16) on which a plurality of gas sensors (18a to 18d) are arranged at a predefined distance from one another. The gas sensors (18a to 18d) are all sensitive to the gas (12) to be detected. The evaluation unit (20) generates a switching signal (22) on the basis of the rationality test, said switching signal representing the presence of the gas (12) in the spatial region (14). The rationality test correlates the first gas detection signal (26a) and the at least second gas detection signal (26b) to each other as a function of the respective accommodation position (24a, 24b, 24c) of the gas sensor.

Description

Technical Field

[0001] This invention relates to an apparatus for failure-safe detection of gases in space regions, and particularly to an apparatus for failure-safe detection of hydrogen. Background Technology

[0002] In many cases, it is desirable or necessary to know whether a particular gas is present in a certain quantity or concentration in a space. Examples include process control and / or exhaust gas monitoring in industrial plants, biogas plants, or gas-powered vehicles; air pollutant monitoring; leak monitoring in gas storage tanks and gas pipeline systems; and last but equally important, monitoring as part of explosion-proof measures. The latter can be performed alone or in combination with other types of monitoring mentioned here as examples.

[0003] Suitable gas sensors are required for gas detection and, if necessary, for measuring gas concentration. Depending on the gas type and the requirements for selectivity, sensitivity, and stability, various measurement principles utilizing the chemical and / or physical properties of the gas to be detected can be used. Typically, gas sensors generate an electrical signal that depends on the concentration of the gas to be detected, and this signal can be further processed in subsequent evaluation and / or control units.

[0004] As an example, EP 1 879 023 A1 discloses a gas sensor and its use for detecting hydrogen. The gas sensor has a field-effect transistor (FET), wherein the FET has: an electrically floating gate and a gate of a sensor layer having a sensitive layer for detecting hydrogen (H2). The sensor layer is separated from the measurement chamber by a separation layer comprising SnO2.

[0005] DE 11 2016 004 676 T5 discloses a hydrogen sensor capable of detecting hydrogen with high responsiveness even under normal or low-temperature conditions without the need for heating. The hydrogen sensor includes a substrate with insulating properties, a detection membrane comprising a ceramic material and metal particles dispersed within the ceramic material, and a pair of electrodes disposed on the surface of the detection membrane. The metal particles are made of a palladium (Pd) alloy and at least one other element selected from the transition metal group other than palladium.

[0006] DE 10 2016 212 117 A1 discloses an apparatus and method for detecting leaks in the hydrogen tank of a hydrogen fuel cell vehicle. The leak is detected based on changes in the readings of a high-pressure sensor, indicating a potential leak due to a solenoid valve malfunction.

[0007] DE 10 2021 201 449 A1 discloses another sensor device for a hydrogen storage system in a motor vehicle. The hydrogen storage system has a hydrogen storage tank and a pressure reducing valve connected to the tank, which allows hydrogen to expand from the tank pressure to a lower supply pressure for a fuel cell system. The sensor device includes a pressure reducing valve configured for detecting hydrogen and a hydrogen sensor.

[0008] In many situations, especially within the context of explosion-proof measures, early detection of leaks in gas delivery, production, and / or processing systems (such as electrolyzers or fuel cells, gas tanks, and / or gas pipeline systems) is crucial for safety. Typically, safety measures are initiated once an unexpected gas leak or an unacceptably high gas concentration is detected in the system. These measures may include issuing audible and / or visual alarms to evacuate the affected area, ventilating the affected area by automatically opening ventilation flaps and / or doors, and emergency shut-off valves. Such safety measures often result in an interruption to the ongoing process of using the gas. This is detrimental to the productivity and efficiency of equipment using the gas. Therefore, it is desirable to avoid false alarms that disrupt normal system operation, in terms of objectively unnecessary interruptions. For example, the gradual degradation of sensors, such as decreased sensitivity, or even sensor malfunctions providing incorrect data, can lead to false alarms in this sense. On the other hand, the productivity and efficiency of equipment must not be sacrificed for safety. Safety measures are necessary in cases of doubt, gas detection, and uncertainty. In many cases, this means that if the control system, the sensors and actuators connected to the control system, the communication connections, and / or other places that may endanger people and / or the environment malfunction, the equipment must be shut down or otherwise brought to a safe state. Summary of the Invention

[0009] In this context, the object of the present invention is to provide a device of the type mentioned at the beginning, which on the one hand can perform fault safety detection of gas in a space region, and on the other hand helps to reduce or even avoid false alarms.

[0010] According to one aspect of the invention, an apparatus of the type mentioned at the outset is provided, comprising a spacer including a plurality of gas sensors disposed on the spacer at a defined distance relative to each other, each gas sensor being sensitive to a gas to be detected, and including an evaluation unit configured to generate a switching signal based on the gas sensors, the switching signal indicating the presence of a gas in a spatial region, wherein the spacer defines a first accommodating position and at least a second accommodating position spaced apart from each other, wherein a first gas sensor from the plurality of gas sensors is disposed at the first accommodating position and configured to generate a first gas detection signal indicating a first gas concentration near the first accommodating position, wherein a second gas sensor from the plurality of gas sensors is disposed at the second accommodating position and configured to generate a second gas detection signal indicating a second gas concentration near the second accommodating position, and wherein the evaluation unit is configured to determine the defined switching signal based on a plausibility test, wherein the plausibility test correlates the first gas detection signal and the second gas detection signal with respect to the first accommodating position and the second accommodating position.

[0011] Such a device is particularly advantageous when used as a leak sensor to detect uncontrolled or unintentional gas escape from gas containers or gas pipeline systems, especially from gas containers or gas pipeline systems storing and / or transporting hydrogen. Gas containers and / or gas pipeline systems can be components of gas production systems and / or gas handling systems.

[0012] The device has multiple gas sensors arranged on a common spacer body. The spacer body thus houses the individual gas sensors at designated locations with a defined distance relative to each other. In a preferred exemplary embodiment, the spacer body is an inherently stable component, allowing the gas sensors to be fixed at the defined distance relative to each other before the device is installed as a whole for gas detection in a space region. Therefore, in these exemplary embodiments, the spacer body connects a first gas sensor and a second gas sensor to form a sensor head having at least two individual gas sensors arranged at a defined distance from each other. Preferably, the spacer body is made of metal, plastic, fiber composite material, or a combination of these materials to ensure sufficient robustness to environmental conditions such as temperature fluctuations and / or mechanical stress. In a preferred exemplary embodiment, the first and second housing locations are spaced apart by a defined distance within a range of several centimeters, particularly between 1 cm and 50 cm, preferably between 5 cm and 25 cm, each including a specified range limitation.

[0013] The defined distance between the first and second gas sensors allows for checking the reasonableness of the first and second gas detection signals relative to each other. Advantageously, this defined distance enables spatially resolved determination of gas concentrations, and the evaluation unit is configured to generate a switching signal based on the spatially resolved gas concentrations. In some exemplary embodiments, the evaluation unit may be configured to generate the switching signal based on a predefined ratio of the first and second gas concentrations. The predefined ratio may advantageously be determined as the difference and / or quotient of the gas detection signals or the gas concentrations thereby represented.

[0014] Therefore, the evaluation unit is configured to determine a defined switching signal based on a plausibility test that correlates the first gas detection signal and the second gas detection signal with each other, taking into account predefined (and therefore known) containment locations. Specifically, the evaluation unit considers the expectation that the defined containment locations of the first and second gas sensors in the device will be present. In some exemplary embodiments, this expectation may include the first gas detection signal appearing before the second gas detection signal, for example, because the second containment location is farther from a possible leak point on the gas cylinder or tubing than the first containment location. Advantageously, gas sensors contained at a distance from each other can be used to determine the flow direction of the gas to be detected, and the evaluation unit can be configured to generate a switching signal based on the flow direction. Alternatively or additionally, the time offset between the first and second gas detection signals may also be due to the fact that the device has a gas conduit configured to supply leaking gas to the first and second gas sensors at different times. A plausibility test can advantageously evaluate the time offset.

[0015] Alternatively or additionally, the expectation may be that the first gas concentration and the second gas concentration are at a defined ratio relative to each other. For example, the expectation may be that, although the containment locations are spaced apart, the first gas concentration and the second gas concentration are substantially the same after a defined time period, i.e., within a defined tolerance interval. In other exemplary embodiments, the expectation may include that the first gas concentration and the second gas concentration exhibit substantially the same time progression, particularly the same type of change in gas concentration over time.

[0016] Reasonableness testing is conducted with knowledge of and consideration of the defined containment locations, and therefore depends on both the first and second containment locations. In some exemplary embodiments, the risk of false alarms can be reduced by having the evaluation unit generate a switching signal only when the first and second gas detection signals are consistent with each other within the expected range, i.e., when observed together, they consistently indicate gas detection. In a further exemplary embodiment, the evaluation unit can generate a switching signal indicating the presence of gas in the space area when one of the gas sensors of the device provides a corresponding gas detection signal. In these exemplary embodiments, the device achieves a higher level of fail-safety in terms of the functional safety of the technical system, according to EN IEC 61508, EN IEC 61062, and / or EN ISO 13849. In some preferred exemplary embodiments, the evaluation unit can be configured by a user via a configuration interface to optionally obtain higher availability of the monitored system in terms of avoiding false alarms or higher fail-safety. In some exemplary embodiments, this configuration can also be extended to the device's explosion-proof features, enabling customized use in a space area assigned to one of explosion-proof zones 1, 2, or 3.

[0017] Therefore, overall, the new device can perform fail-safe detection of gases in the space area while reducing false alarms. Avoiding false alarms increases user acceptance and reduces the incentive to manipulate the system to suppress false alarms or improve availability, such as by disabling gas concentration monitoring. Thus, the aforementioned objectives are fully achieved.

[0018] In a preferred embodiment of the invention, each gas sensor has a defined gas inlet surface, and the gas inlet surfaces of the first gas sensor and the second gas sensor point in different spatial directions.

[0019] In this improvement, the rationality test advantageously also considers the different orientations of the gas entry surfaces of the first and second gas sensors, and the resulting relationship between the first and second gas detection signals. For example, this improvement is advantageous in distinguishing between directional airflow and substantially uniform gas distribution in a spatial region, and in determining whether a switching signal should be generated by the evaluation unit. Furthermore, this improvement can advantageously facilitate the time offset between the first and second gas detection signals. Such a time offset can be advantageously considered in the rationality test.

[0020] In a further improvement, the spacer defines a third accommodating position spaced apart from the first and second accommodating positions, wherein a plurality of gas sensors include a third gas sensor disposed in the third accommodating position, wherein the third gas sensor is configured to generate a third gas detection signal representing a third gas concentration in the vicinity of the third accommodating position. Preferably, the third gas sensor has a third gas inlet surface pointing along a third spatial direction, wherein the third spatial direction is different from the first and second spatial directions pointed to by the gas inlet surfaces of the first and second gas sensors.

[0021] The third receiving position is at a defined distance from the first and second receiving positions. Therefore, this improvement increases the number of relationships the evaluation unit can consider in the plausibility test. Preferably, in a further improvement, the evaluation unit is thus further configured to determine the defined switching signal based on a plausibility test that correlates the first and third gas detection signals and / or the second and third gas detection signals with each other. Based on this improvement, the evaluation unit can generate the switching signal based on higher information density and therefore in a more suitable manner, which helps to further reduce false alarms and achieve a high level of fail-safety.

[0022] Furthermore, this improvement has the advantage that the new device can be configured more individually and with more variations. Therefore, even without extended rationale testing, the third gas sensor has its advantages.

[0023] In a further improvement, the evaluation unit has a configuration interface configured to select a decision structure from a plurality of predefined decision structures, wherein the plurality of predefined decision structures include a 100X decision structure and a 200X decision structure using a first gas sensor and a second gas sensor, and wherein the evaluation unit determines a defined switching signal based on the selected decision structure.

[0024] The decision structure for this improvement defines the logical interconnection between multiple gas sensors and its impact on the generation of switching signals in the evaluation unit. A 1ooX (one of X) structure means that the evaluation unit generates a switching signal once one of the X gas detection signals indicates the presence of a defined gas concentration in the space region. Here, the letter X represents the number of gas sensors available for this structure. Therefore, for two gas sensors, 1ooX represents 1oo2 (one of two). By using a 2oo2 (two of two) decision structure for the first and second gas sensors, the evaluation unit generates a switching signal only when the first and second gas detection signals indicate defined first and second gas concentrations, respectively. In an exemplary embodiment of the device with a third gas sensor, the multiple predefined decision structures preferably further include at least one of the following decision structures: 1oo3, 2oo3, and / or 3oo3. In a further advantageous exemplary embodiment of the device with a fourth gas sensor, the multiple predefined matching structures further include at least one of the following decision structures: 1oo4, 2oo4, 3oo4, and / or 4oo4. This improvement expands the application range of the new device and allows users to easily and flexibly adapt it to their intended use. It also provides an efficient spare parts inventory for different operating conditions.

[0025] In a further improvement, the device includes an umbrella-shaped housing covering the spacer and at least one gas sensor.

[0026] In this improvement, the umbrella-shaped housing has one or more surfaces defining the covered internal space. For example, the one or more surfaces may be curved, such as a spherically segmented curved surface. However, in principle, in other exemplary embodiments, the umbrella surface may be flat. The housing may have several sidewalls adjacent to each other and defining an internal space with a polygonal cross-section. The housing has at least one access opening, particularly on the opening side opposite the umbrella surface. Alternatively or additionally, the housing may have several access openings, particularly lateral access openings in the umbrella surface. In some exemplary embodiments, the umbrella surface is located above the gas sensor at the device's usage location, i.e., in the intended direction of the device, and is closed at the top. The advantage of this improvement is that the housing collects the gas to be detected in the area of ​​at least one gas sensor, thereby facilitating a defined detection condition. This, in turn, makes it possible to design a reasonable test with tighter tolerances. In some preferred exemplary embodiments, the umbrella-shaped housing covers a first gas sensor and a second gas sensor. Preferably, one gas sensor is arranged deeper in the umbrella-shaped housing than the other, i.e., positioned closer to the umbrella surface. This improvement helps to generate switching signals with particular sensitivity and significance.

[0027] In a further improvement, the umbrella-shaped housing has a partition wall that divides the umbrella-shaped housing into a first chamber and a second chamber, wherein a first gas sensor is arranged in the first chamber and a second gas sensor is arranged in the second chamber.

[0028] In this improvement, the first and second gas sensors are not only spaced apart from each other, but also arranged in chambers that are at least partially separated from each other. These chambers create distinguishable detection environments, and each chamber contributes to increasing the concentration, making rigor testing more meaningful. This improvement contributes to the realization of particularly sensitive and reliable detection devices.

[0029] In a further improvement, the umbrella-shaped housing has an open side, and the first gas sensor points to the open side.

[0030] In this improvement, the gas to be detected arrives at the first gas sensor at a specific time earlier than the second gas sensor, which facilitates plausibility testing and makes it more reproducibly reliable.

[0031] In a further improvement, the spacer has a tapered outer profile that defines the accommodating position.

[0032] In this improvement, the outer diameter of the first end of the spacer is smaller (i.e., more "pointed") than the opposing second end. In some advantageous exemplary embodiments, the tapered first end may be closer to the opening side than the second end. The advantage of this improvement is that the shape of the spacer facilitates gas entry into the housing in a defined manner. This improvement helps to detect gas quickly and advantageously. In other exemplary embodiments, the wider second end may be closer to the opening side than the tapered first end. This variation facilitates a time offset between the first gas detection signal and the second gas detection signal, thereby contributing advantageously to a highly reliable and meaningful switching signal.

[0033] In a further improvement, the spacer includes a tetrahedron or pyramid, on which the first gas sensor and the second gas sensor are arranged.

[0034] A tetrahedron is a multifaceted three-dimensional solid with a minimum number of flat or substantially flat outer surfaces and a minimum number of corners. It also has a tapered outer profile, benefiting from the aforementioned advantages, similar to a pyramidal spacer. The tetrahedron allows for the particularly advantageous placement of up to four gas sensors on its surfaces or corners. With gas sensors arranged in this manner, the 3D spatial volume can be monitored "all around" to determine the rationale relationship with a small number of gas sensors. Pyramidal spacers offer similar advantages but require more gas sensors to monitor the 3D spatial volume "all around" in the same manner for rationale relationship. The advantage of both designs is that gas sensors can be placed relatively easily on preferably flat surface portions and / or corners. Preferably, the gas sensors are embedded in surface portions and / or corners, which facilitates mechanical protection of the gas sensors, thereby improving the robustness of the device.

[0035] In a further improvement, the spacer includes a curved surface on which the first gas sensor and the second gas sensor are arranged.

[0036] In this improvement, the spacer can, for example, have a spherical segmented shape, a cylindrical or conical outer surface that defines the accommodating position of the gas sensor. This improvement allows for the very efficient and uniform distribution of multiple gas sensors with gas inlet surfaces facing different directions, and enables multiple plausibility checks.

[0037] In a further improvement, the multiple gas sensors include at least two different types of gas sensors selected from the group consisting of electrochemical gas sensors, semiconductor gas sensors, catalytic gas sensors, or optical gas sensors, particularly infrared gas sensors. In some exemplary embodiments of this improvement, the difference in type may be based on the material properties of the gas sensors, even if the physical measurement principle is otherwise the same.

[0038] Electrochemical sensors use electrochemical cells, where a chemical reaction between a gas and an electrode produces a measurable electrical signal. They are well-suited for accurate measurements at low concentrations. Semiconductor gas sensors measure changes in the electrical properties of a semiconductor material caused by the presence of a target gas. They are relatively inexpensive and react rapidly, but can be affected by other gases. Catalytic gas sensors have two electrodes, typically in the form of platinum coils embedded in a ceramic layer and electrically connected by a bridge circuit. One electrode surface is activated with a catalyst that promotes oxidation, while the other is deactivated. A current flowing through the electrodes heats them, and on the surface of the activated electrode, oxygen from the air reacts with the target gas. This causes an increase in temperature and resistance in the activated electrode, unbalancing the bridge circuit, which can then be measured. Optical gas sensors utilize the principles of light absorption or scattering to detect gas concentration. Such gas sensors are very accurate and generally robust, but can be expensive.

[0039] In this improvement, the device has at least two gas sensors whose detection capabilities are based on different physical and / or chemical principles and / or different material properties of the sensitive surfaces. Due to the different detection principles, different types of gas sensors can be subjected to particularly meaningful rationale testing and contribute to achieving a particularly high level of fail-safety according to the aforementioned functional safety standards.

[0040] In a further improvement, the device has a rotary drive that defines a rotation axis, and the evaluation unit is configured to use the rotary drive to rotate at least one gas sensor about the rotation axis.

[0041] Preferably, the evaluation unit is configured to rotate the spacer about a rotation axis. This improved arrangement allows the evaluation unit to change the spatial position of at least one gas sensor to analyze the direction of airflow. In a sense, this improved arrangement can "sniff out" an increase in gas concentration. Preferably, the evaluation unit is configured to generate a switching signal based on the current rotational position of at least one gas sensor. This improvement allows for more targeted generation of the switching signal.

[0042] In further improvements, the rationality test involves calculating the difference between the first gas detection signal and the second gas detection signal.

[0043] Calculating this difference enables a very rapid comparison between the first gas detection signal and the second gas detection signal, and thus helps to achieve a detector device with a very fast response in a cost-effective manner.

[0044] In further improvements, a rationality test is conducted to evaluate the time interval between the first gas detection signal and the second gas detection signal.

[0045] This improvement makes excellent use of the spaced-out locations of the gas sensor to enable meaningful switching signals with a low false alarm probability.

[0046] It should be understood that, without departing from the scope of the invention, the above features and the features to be explained below can be used not only in the combinations specified in each case, but also in other combinations or individually. Attached Figure Description

[0047] Exemplary embodiments of the present invention are shown in the accompanying drawings and explained in more detail in the following description. They are shown as follows:

[0048] Figure 1 This is a schematic diagram of an exemplary embodiment of the new device.

[0049] Figure 2 This is a schematic diagram illustrating the time progression of the first gas detection signal and the second gas detection signal.

[0050] Figure 3 This is a simplified representation of another exemplary implementation of a gas sensor on a shared spacer, and

[0051] Figure 4 This is a simplified representation of another exemplary implementation of a gas sensor on a shared spacer. Detailed Implementation

[0052] exist Figure 1 In the accompanying drawings, exemplary embodiments of the new device are generally indicated by reference numeral 10. The device 10 is configured to detect gas 12 in a space region 14 and is advantageously used, for example, to detect gas leaks in gas tanks and / or gas pipeline systems (not shown) so as to trigger safety functions upon gas detection.

[0053] The device 10 includes a spacer 16 on which a plurality of gas sensors 18a to 18d are arranged. All gas sensors 18a to 18d are sensitive to the gas 12 to be detected. In a preferred exemplary embodiment, the gas sensors are sensitive, for example, to hydrogen (H2). Alternatively or additionally, the gas sensors 18a to 18d may be sensitive to other gases. In some preferred exemplary embodiments, the gas sensors 18a to 18d include at least two gas sensors of different types selected from the group consisting of electrochemical gas sensors, semiconductor gas sensors, catalytic gas sensors, and infrared gas sensors. In other exemplary embodiments, the gas sensors 18a to 18d are gas sensors of the same type, particularly semiconductor gas sensors sensitive to hydrogen.

[0054] The device 10 also has an evaluation unit 20, which is configured to generate a switching signal 22 based on gas sensors 18a to 18d. The switching signal 22 sends a signal to the control system (not shown here) indicating that gas has been detected in the space area 14, and can be advantageously used to trigger safety measures in the installed equipment of the space area 14, such as optical and / or acoustic alarms, automatic opening of ventilation dampers and / or automatic closing of shut-off valves.

[0055] In this exemplary embodiment, the spacer 16 is a tetrahedron having four sides and four corners. In this exemplary embodiment, the four corners define a first receiving position 24a for receiving a first gas sensor 18a, a second receiving position 24b for receiving a second gas sensor 18b, a third receiving position 24c for receiving a third gas sensor 18c, and a fourth receiving position (not shown) for receiving a fourth gas sensor 18d. The first gas sensor 18a is configured to generate a first gas detection signal 26a representing a first gas concentration near the first receiving position 24a. The second gas sensor 18b is configured to generate a second gas detection signal 26b representing a second gas concentration near the second receiving position 24b. The third gas sensor 18c is configured to generate a third gas detection signal 26c representing a third gas concentration near the third receiving position 24c. Finally, the fourth gas sensor 18d is configured to generate a fourth gas detection signal 26d representing a fourth gas concentration near the fourth receiving position. Figure 1 It can be seen that the various accommodating locations and the gas sensors 18a to 18d arranged at each accommodating location are spaced apart from each other. The corresponding distance between gas sensors 18a to 18d means that the corresponding gas concentrations measured at accommodating locations 24a, 24b, and 24c may differ from each other, depending on whether the gas to be detected diffuses in the area surrounding the spacer 16 and the rate of diffusion in the area surrounding the spacer 16. When the evaluation unit 20 determines the defined switching signal 22 based on a plausibility test that correlates the first gas detection signal 26a with the other gas detection signals 26b to 26d, the distance between each pair of gas sensors defined and fixed by the spacer 16 is advantageously considered in the evaluation unit.

[0056] Gas sensors 18a to 18d each have gas inlet surfaces 28a, 28b, 28c, and 28d. Preferably, the gas inlet surfaces 28a, 28b, 28c, and 28d of gas sensors 18a to 18d point in different spatial directions. For example, the first spatial direction pointed to by the gas inlet surface 28a of the first gas sensor 18a is indicated by reference numeral 30a. The second spatial direction pointed to by the gas inlet surface 28b of the second gas sensor 18b is indicated by reference numeral 30b. The third spatial direction pointed to by the gas inlet surface 28c of the third gas sensor 18c is indicated by reference numeral 30c. In some exemplary embodiments, different spatial directions can be advantageously considered in the rationality test of the evaluation unit 20.

[0057] Reference numeral 32 indicates a monitor for the configuration interface 32 used by the evaluation unit 20. In a preferred exemplary embodiment, the configuration interface 32 allows selection of a decision structure from a plurality of predefined decision structures 34. The selected decision structure defines how the evaluation unit 20 determines a switching signal based on the gas detection signals 26a to 26d from the gas sensors 18a to 18d. For example, if a gas detection signal from one of the gas sensors 18a to 18d indicates a gas concentration higher than a defined threshold, the evaluation unit 20 can generate a switching signal 22 regardless of whether other gas detection signals also indicate such a gas concentration. In this case, the evaluation unit 20 generates a switching signal with a 1oo4 (one out of four) decision structure. The 1oo4 decision structure provides a high level of safety in gas detection and enables the monitored system to achieve a high Safety Integrity Level (SIL) according to EN IEC 61508 and EN IEC 61062 standards and / or a Performance Level (PL) according to EN ISO 13849 standards. Furthermore, such a decision structure is well-suited for explosion protection measures in Zone 0 (i.e., areas with high explosion hazards). The drawback is that this decision structure leads to a higher probability of false alarms. False alarms, in this sense, are the generation of switching signal 22, even though this is not objectively necessary in specific situations. For example, because gas concentrations above the defined threshold exist only locally in very limited quantities, and as the gas continues to diffuse throughout the room, these concentrations weaken to below the defined threshold, thus occurring only occasionally and for short durations.

[0058] Therefore, in a preferred exemplary embodiment, device 10 provides the option to select one of several predefined decision structures 34 via configuration interface 32. In an exemplary embodiment with four gas sensors, configuration interface 32 may advantageously provide the following decision structures for selection: 1oo4, 2oo4, 3oo4, and 4oo4. With the selected 2oo4 decision structure, evaluation unit 20 generates switching signal 22 only when at least two of the four gas sensors 18a to 18d emit signals with gas concentrations higher than a defined threshold. Thus, the 2oo4 decision structure reduces the probability of false alarms and helps improve the availability of the monitored system. The 4oo4 decision structure provides an even lower probability of false alarms and a correspondingly higher availability of the monitored system, but at the cost of fail-safety in the sense of EN IEC 61508, EN IEC 61062, and / or EN ISO 13849 standards.

[0059] In some exemplary embodiments, the configuration interface 32 may be accessible to a user, particularly to the installer of device 10. In other exemplary embodiments, the configuration interface 32 may be reserved for the manufacturer of device 10 and may be inaccessible and / or hidden from the user.

[0060] In the exemplary embodiment shown, the device 10 has an umbrella-shaped housing 36, which in this case has a closed outer surface 38, an open side 39, and a closed bottom 40. In other exemplary embodiments, the housing may have an umbrella surface that curves upward when properly assembled at the point of use, similar to an umbrella being opened upwards.

[0061] Spacers 16, each containing gas sensors 18a to 18d, are arranged within the interior space of a housing 36 formed by an outer surface 38 and a base 40. In this exemplary embodiment, a (preferably but optional) partition wall 42 with a through opening 44 is also arranged within the housing 36. The partition wall 42 forms a first chamber 46 and a second chamber 48 within the umbrella-shaped housing 36. Figure 1 As shown, in this exemplary embodiment, gas sensor 18a is arranged in the first chamber 46, while gas sensors 18b to 18d are located in the second chamber 48. Due to this design, the gas to be detected enters the interior through the opening side 39 of the housing 36 and first reaches the gas sensor 18a, which is closer to the opening side 39. Only after a certain time delay can the gas 12 diffuse into the second chamber 48 and be detected by the gas sensors 18b to 18d located there.

[0062] Therefore, gas sensor 18a generates gas detection signal 26a earlier than the other gas sensors 18b to 18d that can generate corresponding other gas detection signals. The time delay T between gas detection signal 26a and another gas detection signal 26b is schematically shown in... Figure 2 In a preferred exemplary embodiment, the evaluation unit 20 evaluates the signal 22 as part of a rationality test to determine the switching signal 22 based on the gas detection signal.

[0063] In some exemplary embodiments, the evaluation unit 20 may alternatively or additionally consider the different spatial orientations 30a, 30b, 30c of the gas sensors 18a to 18d as part of a plausibility test, since different spatial orientations 30a, 30b, 30c may also cause individual time delays between the gas detection signals 26a to 26d. This is especially true if the gas inlet surface 28a of at least one gas sensor (here, gas sensor 18a) points toward the opening side 39, while the gas inlet surfaces of at least one other gas sensor (here, gas sensors 18b to 18d) point away from the opening side 39.

[0064] In some exemplary embodiments, the evaluation unit 20 may also consider the time relationship between other gas detection signals 26b to 26d. For example, for Figure 1 In the illustrated apparatus, it is anticipated that gas 12 will be detected first by gas sensor 18a, and only after a time delay T by other gas detectors 18b to 18d. Furthermore, if the channel opening 44 in the partition wall 42 allows gas 12 to diffuse substantially uniformly into the second chamber 48, it can be assumed that the other gas detectors 18b to 18d detect gas 12 substantially simultaneously. However, in other exemplary embodiments, it is conceivable that the distribution of the partition wall 42 and / or the other gas sensors 18b to 18d is specifically configured to facilitate a further time delay.

[0065] In some exemplary embodiments, gas sensors 18a to 18d may have different thresholds than each other, thus generating gas detection signals with individually different response thresholds. Evaluation unit 20 may be advantageously configured to evaluate the expected relationship between the gas detection signals as part of a plausibility test and generate switching signal 22 based on the obtained expectations.

[0066] Figure 1 The tetrahedron shown is an exemplary embodiment of spacer 16 with a tapered outer profile. Another exemplary embodiment of such a spacer is as follows: Figure 4 As shown, the spacer 16 includes a curved surface, on which the gas sensor 18 is arranged. The same reference numerals denote the same elements as before.

[0067] A spacer with a tapered outer profile facilitates directional airflow along the spacer from one or more upstream gas sensors to one or more downstream gas sensors. In a preferred exemplary embodiment, the evaluation unit considers the expectations derived from the flow pattern during a plausibility test. Advantageously, the tapered outer profile of the spacer may be hermetically tight and / or have gas-conducting elements or channels to influence the flow pattern in a defined manner. However, in principle, in other exemplary embodiments, it is conceivable that the spacer may have different shapes, such as... Figure 3 As shown.

[0068] In some exemplary embodiments, the plausibility test in the evaluation unit may include forming a difference signal between two or more gas detection signals. The difference signal enables very rapid signal evaluation because when a difference is formed, time-synchronized and consistent gas detection signals result in a zero signal, and any deviation between the gas detection signals can be easily detected in the difference signal.

[0069] like Figure 3 As illustrated, in some exemplary embodiments, the device may include at least one rotary actuator 50 defining a rotation axis 52. In these exemplary embodiments, the evaluation unit may be configured to rotate the spacer 16 and / or the respective gas sensors 18a to 18d about the rotation axis 52, particularly to determine or “sniff out” the direction of the detected airflow.

Claims

1. An apparatus for fault-safe detection of a gas (12) in a space region (14), particularly for fault-safe detection of hydrogen. Includes spacer (16). Includes multiple gas sensors (18a to 18d), said multiple gas sensors (18a to 18d) being housed on said spacer (16) at a defined distance relative to each other, and each gas sensor being sensitive to the gas (12) to be detected, and The evaluation unit (20) is configured to generate a switching signal (22) based on the gas sensors (18a to 18d), the switching signal indicating the presence of gas (12) in the spatial region (14). in, The spacer (16) defines a first receiving position (24a) and at least one second receiving position (24b) spaced apart from each other. The first gas sensor (18a) of the plurality of gas sensors (18a to 18d) is arranged at the first accommodating position (24a) and is configured to generate a first gas detection signal (26a) representing a first gas concentration near the first accommodating position (24a). Among the plurality of gas sensors (18a to 18d), the second gas sensor (18b) is arranged at the second accommodating position (24b) and configured to generate a second gas detection signal (26b) representing the second gas concentration near the second accommodating position (24b), and The evaluation unit (20) is configured to determine a limited switching signal (22) based on a reasonableness test of the first gas detection signal (26a) and the second gas detection signal (26b) relative to each other according to the first accommodating position (24a) and the second accommodating position (24b).

2. The apparatus according to claim 1, wherein, The gas sensors (18a to 18d) each have defined gas inlet surfaces (28a to 28c), and the gas inlet surfaces (28a, 28b) of the first gas sensor (18a) and the second gas sensor (18b) point to different spatial directions (30a, 30b).

3. The apparatus according to claim 1 or 2, wherein, The spacer (16) defines a third accommodating position (24c) spaced apart from the first accommodating position (24a) and the second accommodating position (24b), and wherein the plurality of gas sensors (18a to 18d) includes a third gas sensor (18c) disposed at the third accommodating position (24c), wherein the third gas sensor (18c) is configured to generate a third gas detection signal (26c) representing the concentration of a third gas in the vicinity of the third accommodating position (24c).

4. The apparatus according to claim 3, wherein, The evaluation unit (20) is also configured to determine the defined switching signal (22) based on a plausibility test of relating the first gas detection signal (26a) and the third gas detection signal (26c) and / or the second gas detection signal (26b) and the third gas detection signal (26c) to each other.

5. The apparatus according to claims 1 to 4, wherein, The evaluation unit (20) includes a configuration interface (32) configured to select a decision structure from a plurality of predefined decision structures (34), wherein the plurality of predefined decision structures (34) include a 100X decision structure and a 200X decision structure using the first gas sensor (18a) and the second gas sensor (18b), and wherein the evaluation unit (20) determines the defined switching signal (22) based on the selected decision structure.

6. The apparatus according to any one of claims 1 to 5, further comprising an umbrella-shaped housing (36) covering at least one of the gas sensors (18a to 18d) and the spacer (16).

7. The apparatus according to claim 6, wherein, The umbrella-shaped housing (36) has a partition wall (42) dividing the umbrella-shaped housing (36) into a first chamber (46) and a second chamber (48), wherein the first gas sensor (18a) is arranged in the first chamber (46) and wherein the second gas sensor (18b) is arranged in the second chamber (48).

8. The apparatus according to claim 6 or 7, wherein, The umbrella-shaped housing (36) has an opening side (39), wherein the first gas sensor (18a) points to the opening side (39).

9. The apparatus according to any one of claims 1 to 8, wherein, The spacer (16) has a tapered outer profile that defines the receiving positions (24a to 24c).

10. The apparatus according to any one of claims 1 to 9, wherein, The spacer (16) includes a tetrahedron or pyramid, and at least the first gas sensor (18a) and the second gas sensor (18b) are arranged on the tetrahedron or pyramid.

11. The apparatus according to any one of claims 1 to 10, wherein, The spacer (16) includes a curved surface, on which at least the first gas sensor (18a) and the second gas sensor (18b) are arranged.

12. The apparatus according to any one of claims 1 to 11, wherein, The plurality of gas sensors (18a to 18d) include at least two different types of gas sensors selected from the group consisting of electrochemical gas sensors, semiconductor gas sensors, catalytic gas sensors or infrared gas sensors.

13. The apparatus according to any one of claims 1 to 12, further comprising a rotary driver (50) defining a rotation axis (52), and wherein, The evaluation unit (20) is configured to use the rotary driver (50) to rotate at least one gas sensor (18a to 18d) about the rotation axis (52).

14. The apparatus according to any one of claims 1 to 13, wherein, The rationality test evaluates the time interval between the first gas detection signal (26a) and the second gas detection signal (26b).

15. Use of an apparatus according to any one of claims 1 to 14, wherein the apparatus is used as a leak sensor to detect uncontrolled gas escape from a gas container or gas pipeline system.

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