• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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  • 优先权
    • 专利摘要:
    The gas sensor device for measuring a target gas concentration comprises: a radiation device (3, 4) for emitting radiation energy through a space (2) containing the target gas; a radiation receiving device (5) for detecting the radiation energy emitted by the radiation device (3, 4); a filter device (6) which is associated with the radiation receiving device (5) and passes radiation of a wavelength range corresponding to the target gas; and a control and evaluation system (7) which is connected to the radiation receiving device (5) and which calculates the target gas concentration on the basis of a detection signal applied to the control system and evaluation (7) by the radiation receiving device (5). In order to provide a gas sensor device for the measurement of a target gas concentration, which can be achieved with a relatively low expenditure in terms of technology and design and which can perform extremely reliable measurements and In particular, for states requiring measurements to eliminate risks, it is proposed that the gas sensor device (1) is designed as a non-dispersive infrared spectroscopic (NDIR) gas sensor device (1), that the device radiation (3, 4) of the NDIR gas sensor device (1) has at least two sources of infrared radiation (3, 4), and that each of the sources of infrared radiation (3, 4), at least two, the radiation device (3, 4) of the NDIR gas sensor device (1) is arranged at a different optical distance from the radiation receiving device (5), produced as a radiation receiver device infrared sensor (5) of the NDIR gas sensor device (1).
    公开号:FR3023917A1
    申请号:FR1556695
    申请日:2015-07-16
    公开日:2016-01-22
    发明作者:Ralf Monkemoller
    申请人:Paragon AG；
    IPC主号:
    专利说明:

    [0001] The present invention relates to a gas sensor device for measuring a concentration of target gas, comprising: a radiation device for emitting energy radiation through a space containing the target gas; a radiation receiver device for detecting the radiation energy emitted by the radiation device; a filter device which is associated with the radiation receiving device and passes radiation of a wavelength range corresponding to the target gas; and a control and evaluation system which is connected to the radiation receiving device and which calculates the target gas concentration on the basis of a detection signal applied to the control and evaluation system by the receiver device. radiation. Gas sensor devices of this type are increasingly used to monitor air quality, in particular to monitor outdoor air quality and / or air quality in enclosed spaces, in particular as well. motor vehicle interiors. When monitoring air quality in closed spaces, it is to be ensured that, in the event of a deterioration of this air quality, it is possible to react by taking the appropriate measures.
    [0002] In the automotive field, suitable gas sensor devices have been used for some time, including metal oxide sensors (MOS) for monitoring air to detect the presence of VOCs (volatile organic compounds). When the concentrations of these VOCs in the air of the passenger compartment of the vehicle are too high, the use of this type of gas sensor device automatically activates the ventilation of the vehicle to ensure the renewal of the air. In motor vehicles, air conditioning installations in which the refrigerant is carbon dioxide (CO2) are used more and more frequently. Since carbon dioxide, when its concentration in the cabin air increases, can cause fatigue and drowsiness in the driver, gas sensor devices are also used to monitor leaks in the installation. air conditioning. In these cases, the gas sensor device, which is implemented as a CO2 sensor device, must trigger an alarm in the event of an inadmissible concentration of CO2 in the air of the passenger compartment, or must act on a control device of a vehicle ventilation, with the aim of eliminating the risk of excessively high CO2 content in the cabin air. This could be achieved for example by increasing the flow of air in the passenger compartment, which has the effect of reducing the concentration of CO2 inside the passenger compartment of the vehicle.
    [0003] Document DE 10 2004 024 284 A1 discloses a method for monitoring the air quality in a vehicle interior, according to which a gas sensor device, adapted to detect CO2, must eliminate any risk for human beings. live in the passenger compartment of a parked vehicle. To this end, we monitor not only the CO2 content of the cabin air, but also the temperature of the passenger compartment. If, in the event of a relatively high temperature of the passenger compartment, a predefinable CO2 increase gradient is detected, it is assumed that a living being, for example a child or a pet, is in the passenger compartment. 'a vehicle. Here, the CO2 growth gradient is characteristic of breathing inside the vehicle. From the state of the art described at the beginning, the object of the invention is to propose a gas sensor device, intended to measure a target gas concentration, which can be produced with a relatively low expense in terms of technique. and design, which allows extremely reliable and accurate measurements to be made, especially under conditions where measures are necessary to eliminate the risks.
    [0004] According to the invention, this object is achieved by the fact that the gas sensor device is designed as a non-dispersive infrared spectroscopy (NDIR) gas sensor device, that the radiation device of the NDIR gas sensor device exhibits at minus two sources of infrared radiation, and that each of the at least two infrared radiation sources of the radiation device of the NDIR gas sensor device is disposed at a different optical distance from the radiation receiving device, realized as an infrared radiation receiver device, the NDIR gas sensor device. Alternatively, the solution may be that, apart from producing the gas sensor device as an NDIR device, the radiation receiving device of the NDIR gas sensor device has at least two infrared radiation receiving units, and that each of the at least two infrared radiation receiving units of the radiation receiving device of the NDIR gas sensor device is disposed at a different optical distance from the radiation device, as a source of infrared radiation, of the NDIR gas sensor device. Since, at present, the economic investment for radiation receiving devices is higher than for radiation sources, it is currently preferred to produce the NDIR gas sensor device according to the invention with two sources of radiation. infrared radiation and an infrared radiation receiving unit. According to the invention, different measurement paths are realized in the case of the NDIR gas sensor device, and depending on the type of requirements and the purpose of the measurement, the appropriate measuring path can serve as a basis for the measurement. . Measuring paths or longer optical paths provide greater sensitivity and thus higher resolution and accuracy for low concentrations of the target gas. On the other hand, in the presence of very high concentrations of the target gas, a long optical path has the effect that the gas sensor device reaches a state of saturation. Despite target gas concentrations that continue to increase, it is no longer possible to modify with a relatively low economic investment the infrared radiation energy received by the infrared radiation receiving unit. For high concentrations, the relatively short optical path between the infrared radiation source and the infrared radiation receiving unit can be used. However, it is accompanied by a relatively low sensitivity and thus a low resolution for low concentrations of the target gas. In the case of the NDIR gas sensor device according to the invention, it is possible to implement an appropriate operating mode, according to the requirements concerning the signal quality and according to the target gas concentrations detected.
    [0005] Since the gas sensor device according to the invention is embodied as an NDIR gas sensor device, it is possible to guarantee a more reliable and more precise implementation, since the transverse sensitivity of NDIR gas sensor devices to insignificant gases for the measurement and especially the humidity of the air is very low compared to other gas sensor devices intended for the uses in question here, in particular devices equipped with metal oxide sensors. The NDIR gas sensor device comprises the infrared radiation device and the infrared radiation receiving unit. In front of the infrared radiation receiving unit is placed the filter device which passes to the infrared radiation receiving unit only the wavelength which is of interest for the measurement concerned. This wavelength is a function of the Target gas to watch. For an NDIR gas sensor device intended to detect the CO 2 content, this wavelength is, for example, 4.26 μm, since here is one of the CO 2 absorption bands. In the case where the NDIR gas sensor device is used to monitor HC (hydrocarbons), a wavelength of, for example, 3.3 μm is chosen.
    [0006] The infrared radiation receiving unit of the NDIR gas sensor device measures the energy transmitted by the infrared radiation device to the infrared radiation receiving unit. If the target gas whose concentration is to be measured appears in the ray path between the infrared radiation device and the infrared radiation receiving unit, a portion of the radiation energy at the specific wavelength is absorbed by the target gas lying on the ray path. According to the Beer-Lambert law, this absorption depends inter alia on the average length of the optical path of the measuring path between the infrared radiation device and the infrared radiation receiving unit and the concentration of the target gas. The statement of the Beer-Lambert law is: I = Io - 10 "- - d Here, Io is the transmitted energy without target gas c is the target gas concentration d is the average optical path length of the measuring path between the infrared radiation source and the infrared radiation receiver and is a constant which is a function of the target gas.
    [0007] The concentration of the target gas c is determined according to the formula above. Ideally, Io, d and E are constant. In this case, it would be sufficient to measure the transmitted energy I, using the infrared radiation receiving unit, and to calculate the target gas concentration c using the formula. The higher the target gas concentration c, the lower the energy transmitted. This is important because all the influencing factors causing a decrease in energy transmission lead to values that are too high for the target gas concentration c.
    [0008] In order to obtain an accurate measurement result, it is a prerequisite that the radiated power of the infrared radiation device is constant even over a very long period of time, for the wavelength specific to the intended measurement. On the other hand, the average length of the optical path of the measurement path between the infrared radiation device and the infrared radiation receiving unit must not be changed. For example, when reflecting surfaces are used to increase the quality of the detection signal of the NDIR gas sensor device, so that a larger portion of the radiation energy emitted by the infrared radiation device can be focused. on the infrared radiation receiving unit, it is very important that the reflective properties of the materials constituting the reflective surfaces are stable and do not change, even during a possibly considerable life of the NDIR gas sensor device. Otherwise, a decrease in reflectivity or a decrease in the radiated power of the infrared radiation device would still be interpreted as too high a concentration of the target gas. Depending on the use of the NDIR gas sensor device according to the invention, a false alarm may then be triggered, which is of course to avoid. In order to reduce the aging of the infrared radiation source of the NDIR gas sensor device and also to reduce the electrical energy consumption of the NDIR gas sensor device, it is for example known from the state of the art to operate the infrared radiation source in pulsed mode. Thus, for some applications and functions, it is sufficient that an updated measurement value is available every 5 seconds. In this case, the infrared radiation source is activated only every 5 seconds, until it has reached its full radiation power. For this purpose, 500 to 1000 milliseconds are often sufficient. After a defined time interval, the reception power is then measured on the infrared radiation receiver, and the downstream control and evaluation device calculates the target gas concentration from the obtained detection signal. In the case where the NDIR gas sensor device is powered by a battery as a source of electrical energy, the pulsed operating mode, known from the state of the art, also causes an energy absorption which is too high. for many uses. To solve this problem, it is provided, in the case of the NDIR gas sensor device according to the invention, that the infrared radiation device of the NDIR gas sensor device can be powered with different powers. This allows for considerable additional energy savings. Thus, in the case where the NDIR gas sensor device is used for the detection of CO2 leaks from a vehicle air conditioning installation, it is for example useful and judicious to provide an alarm threshold value. which is greater than a target gas concentration or CO2 of 10,000 ppm (1.0% by volume). The upper limit of the measuring range which is useful for this purpose is often above 100 000 ppm (10.0% by volume). When it is desired to detect whether a living being is inside a passenger compartment, the NDIR gas sensor device requires a measuring range totally different from that required for the aforementioned detection of a CO2 leak of an installation air conditioning. If the NDIR gas sensor device is used to detect the presence of living beings in a passenger compartment, this requires a high resolution and accuracy of the detection signal characterizing the CO2 concentration in a concentration range up to 1000 ppm. (0.1% by volume). This will be illustrated with the following example: A sleeping infant is breathing at approximately 20 breaths per minute. The volume of air per breath is about 100 ml. Therefore, for an enrichment of the respiratory air of 0,04% in volume of CO2, the infant rejects 0,08 1 of CO2 per minute. For one hour, this corresponds to about 5 1 of CO2. When the indoor space to be monitored has a volume of approximately 5 m3, that is to say 5,000 1, the infant caused an increase in the CO2 concentration of 0.1% by volume of CO2 after 'one o'clock. If it is assumed that in full sunlight a motor vehicle achieves critical temperatures of more than 60 degrees C in the passenger compartment within half an hour, the NDIR gas sensor device must be able to reliably detect an increase in 0.05% by volume (500 ppm) of the CO2 concentration. Without the operation, provided according to the invention, of the infrared radiation source of the NDIR gas sensor device with different powers, an NDIR gas sensor device known from the state of the art would have a resolution that is clearly too low in a measuring range between 400 ppm and 5000 ppm. In order to illustrate the advantages of the NDIR gas sensor device according to the invention, it should be added that one of the main energy consumers of such an NDIR gas sensor device is the source of infrared radiation. For an NDIR gas sensor device with a particularly low power consumption, it is therefore necessary to change the operating mode of the infrared radiation source, as known from the state of the art. For this purpose, it is assumed that the radiation energy received in the infrared radiation receiver of the NDIR gas sensor device is proportional to the radiation energy emitted by the infrared radiation source. In turn, the radiation energy emitted by the infrared radiation source depends directly on the electrical energy used for the operation of the infrared radiation source.
    [0009] Therefore, a relatively large transmitted radiation energy means that there is also a relatively large received radiation energy and thus a relatively large or sharp detection signal of the infrared radiation receiver. Such a relatively large detection signal improves the signal-to-noise ratio, so that the measurement result is more accurate and has better resolution. The radiation energy W transmitted from the infrared radiation source to the infrared radiation receiver is proportional to the product of the radiated power I o and the radiation duration T. In order to improve the quality of the signal, it would be possible to increase the radiated power and / or the radiation duration. To reduce the energy absorption of the NDIR gas sensor device, it would be possible to reduce the radiated power and / or the radiation duration. For this purpose, the reduction could be provided in such a way that the detection signal emitted by the infrared radiation receiver still meets the requirements concerning the resolution, the accuracy and the signal-to-noise ratio. For this purpose, the NDIR gas sensor device according to the invention is provided with a control and evaluation system which makes it possible to operate the infrared radiation source with different radiated powers. For this, a voltage source provided for the power supply of the infrared radiation sources can be adjustable, knowing that the adjustment is made by the control and evaluation system. The respective operating voltage of the voltage source makes it possible to set different levels of the radiated power of the infrared radiation sources. In the case of the NDIR gas sensor device 1 according to the invention, it is advantageous that the optical distance between a first source of infrared radiation and the infrared radiation receiving unit or between the infrared radiation source and a first unit The infrared radiation receiving region is relatively small, and the optical distance between a second infrared radiation source and the infrared radiation receiving unit or between the infrared radiation source and a second infrared radiation receiving unit is relatively large. This provides a relatively accurate measurement result for both very low and very high target gas concentrations.
    [0010] In the case of the NDIR gas sensor device 1 according to the invention, all the infrared radiation sources present may preferably be supplied with different powers, so that the range for obtaining exact measurements in a very reliable manner is increased further. Advantageously, the NDIR gas sensor device can be used in at least two modes of operation, and in this case the first source of infrared radiation operates with a very low power in a first mode of operation and the second source of infrared radiation. operates with high power in a second mode of operation. In the first mode of operation, the NDIR gas sensor device according to the invention has a relatively low energy consumption. In this mode of operation, a reduced signal quality is voluntarily accepted and thus the absence of a relatively high resolution, precision and signal / noise ratio. In this mode of operation, priority is given to the relatively low power consumption. In the second mode of operation, the NDIR gas sensor device according to the invention works with a relatively high energy consumption. In this second mode of operation, priority is given to a relatively high quality of the detection signal, i.e., high resolution, high precision, and high signal-to-noise ratio thereof.
    [0011] According to an advantageous improvement of the NDIR gas sensor device according to the invention, it can also work in a third mode of operation, in which the second source of infrared radiation is supplied with a power which is possibly significantly higher, compared to that of the first mode of operation. Thus, it is guaranteed for relatively low target gas concentrations that these target gas concentrations or their increase are accurately measured. As mentioned above, it is known from the state of the art to operate at intervals the infrared radiation source of an NDIR gas sensor device, in order to reduce the energy consumption of the latter. If a reduced measurement rate is sufficient, then the infrared radiation source is only briefly activated to perform each individual measurement.
    [0012] Between measurements, the source of infrared radiation is cut off and therefore does not consume electrical energy. The known intermittent operation further has the advantage that at times when the infrared radiation source is cut off, the signal of the infrared radiation receiver of the NDIR gas sensor device can be collected as a reference point for the evaluation of signal that follows. As mentioned above, there are applications where it is necessary to obtain a minimum energy consumption with a predetermined minimum measurement rate, for example when detecting CO2 leaks from an air conditioning installation operating with CO2. as a refrigerant, in a parked vehicle. The alarm threshold is here for example at a CO2 concentration of 30 000 ppm in the air of the passenger compartment of the vehicle. With a permissive inaccuracy of a few percent, the alarm threshold value must trigger the alarm. The basic content of CO2 in the air is about 380 ppm. In a passenger car occupied by several passengers or persons, the CO2 concentration can reach values up to 1900 ppm. In all cases, the difference with the alarm threshold value of 30 000 ppm mentioned above remains significant. In the example described above, greater than 15. For example, in a vehicle the factor is parked, the average absorbed current of 50 1.1A at 12 V DC (W = 0.6 mWh) must not be exceeded in the state of rest. At the same time, it is necessary to reach a minimum measurement rate of one measurement per minute. For each measurement, therefore, only 0.6 mWh / 60 = 0.01 mWh of electrical energy is available. An infrared radiation source with a rated power of 400 mW could operate for 90 ms with this available electrical energy. However, a typical infrared radiation source for the use of NDIR devices reaches its operating temperature, and thus its total radiated power, only after a few hundred milliseconds. As a result, the reduction of the radiation duration of, for example, 300 ms in the second mode of operation described above to 90 ms in the first mode of operation described above implies a significant decrease in the radiated power and consequently a significant reduction in the quality of the signal. This does not make it possible to reach the required measurement tolerances with respect to the alarm threshold value. For the NDIR gas sensor device according to the invention, these measurement tolerances are attained only by the fact that the infrared radiation source of the NDIR device can operate with different powers. According to an advantageous improvement of the NDIR gas sensor device according to the invention, it is envisaged that the NDIR device can be switched from the first mode of operation to the second mode of operation by its control and evaluation system, as a function of detection signals collected therein when the NDIR gas sensor device is in the first mode of operation. Switching from the first to the second operating mode can be provided in particular when the control and evaluation system detects that a predefined threshold value of the target gas concentration is reached or exceeded.
    [0013] According to another useful improvement of the NDIR gas sensor device according to the invention, it can be switched from the first mode of operation to the second mode of operation by its control and evaluation system, if it is detected in the control and evaluation system that a predefined threshold value of the gradient or increase of the target gas concentration is reached or exceeded. To limit the risks, it can be useful and advantageous to trigger, using the control and evaluation system of the NDIR gas sensor device, an alarm installation and / or a ventilation device or a similar system, if, in the second mode of operation of the NDIR gas sensor device, the control and evaluation system thereof detects that a predefinable alarm value is reached or exceeded.
    [0014] In order to ensure that the NDIR gas sensor device according to the invention, whenever it is judicious and possible, is in its first mode of operation which goes hand in hand with a low energy consumption, it is advantageous that the NDIR gas sensor device according to the invention can be brought back by its control system and evaluation of its second mode of operation to its first mode of operation, if it is detected in the second mode of operation of the NDIR device, by means of of the control and evaluation system, whether the threshold value set for switching from the first to the second operating mode of the NDIR device, or another threshold value set for switching from the second to the first operating mode, is reached or exceeded towards over there. In order to avoid in certain applications that there are permanently switches from the first to the second mode of operation and vice versa, it is advantageous for the control and evaluation system of the NDIR gas sensor device according to the invention to allow to adapt the predefinable threshold value for the first operating mode, for switching to the second operating mode, or the predefinable threshold value for the second operating mode, for switching to the first operating mode of the sensor device NDIR gas, if, in the second operating mode of the NDIR gas sensor device, it is detected by means of the control and evaluation system, that the predefinable alarm threshold value is not reached for a period of predefinable time from the switching of the first to the second operating mode of the NDIR gas sensor device. In order to guarantee, after the parking of a vehicle, both a reliable monitoring of CO2 leaks and a reliable detection of living beings possibly found in the passenger compartment of the vehicle, it is advantageous that, after parking or stopping a motor vehicle equipped with the NDIR gas sensor device to monitor its passenger compartment, this device can operate for a predefinable period of time to change intermittently, with an adjustable ratio, between its first mode of operation and its third mode of operation. The detection signals collected in the first mode of operation make it possible to reliably detect a possible leakage of CO2, and the detection signals provided in the third mode of operation make it possible to reliably detect the presence of a living being in the body. cabin of the vehicle. It is advisable that the control and evaluation system make it possible to start an alarm installation and / or a ventilation device or the like if, in the second and / or third mode of operation of the gas sensor device NDIR, it is detected in the control system and evaluation thereof, that a predefined threshold alarm value is reached or exceeded. Advantageously, in the third mode of operation, the alarm installation and / or the ventilation device can be triggered only if a temperature sensor detects the exceeding of a predefined temperature threshold value and transmits it to the system. order and evaluation. For the optimal operation of the NDIR gas sensor device according to the invention, it is advisable that it can be adjusted automatically, by means of its control and evaluation system, in accordance with an algorithm defined by lapse of time. predefined values and threshold values and predefinable alarm values for detection signals.
    [0015] As explained above, the NDIR gas sensor device according to the invention described above can be advantageously used to measure the concentration of CO2 or the concentration of HC in the passenger compartment of a vehicle.
    [0016] According to a method according to the invention for the use of an NDIR gas sensor device, preferably an NDIR gas sensor device in one of the embodiments described above, there are provided at least two modes of operation of the NDIR device, and in each state of operation of the NDIR gas sensor device, an infrared radiation source of the NDIR device is supplied with a different power, knowing that in a first mode of operation a first source of infrared radiation is supplied with a low power, and in a second mode of operation a second source of infrared radiation is fed with a high power. Suitably, when carrying out the method according to the invention described above, it is provided to switch the NDIR gas sensor device from one mode of operation to another, whenever predefined threshold values are reached or exceeded downwards or upwards. The present invention will be described in detail below with the aid of an embodiment, with reference to the drawing, the single figure of which illustrates an exemplary embodiment of a gas sensor device according to the invention for to measure a target gas concentration. An embodiment of a gas sensor device 1 shown in the single figure is used to measure a concentration of target gas, for example in a space 2. The space 2 may for example be the passenger compartment 2 of a vehicle automobile. The gas sensor device 1 is designed as a non-dispersive infrared spectroscopy (NDIR) gas sensor device 1 and comprises a first source of infrared radiation 3 which makes it possible to emit infrared radiation energy through the space or the cockpit 2 containing a target gas, for example carbon dioxide (CO2). On the other hand, the NDIR gas sensor device 1 comprises a second source of infrared radiation 4 which also makes it possible to emit infrared radiation energy through the space or the passenger compartment 2 containing the target gas. In the exemplary embodiment of the NDIR gas sensor device 1 according to the invention which is shown in the single figure, the first infrared radiation source 3 and the second infrared radiation source 4 constitute the radiation device of the NDIR device. . An infrared radiation receiving unit 5 is disposed at a distance from the first infrared radiation source 3 of the NDIR gas sensor device 1. This infrared radiation receiving unit 5 makes it possible to detect the infrared radiation energy emitted by the first source of infrared radiation 3 through the space or the passenger compartment 2. In the exemplary embodiment of the NDIR gas sensor device 1 which is shown in the sole FIGURE, the distance between the second source of infrared radiation 4 and the infrared radiation receiving unit 5 is significantly larger than the distance between the first infrared radiation source 3 and the infrared radiation receiving unit 5. In the radiation path, between the infrared radiation sources 3, 4 on the one hand and the infrared radiation receiving unit 5 on the other hand, there is provided a filter device 6 which is associated with the reception unit 5 and is designed to pass radiation from a range of wavelengths that corresponds to the target gas. For this purpose, in the case where the CO2 is intended as a target gas, a wavelength range of about 4.26 μm is chosen because here one of the absorption bands of CO2 is located. If the target gas consists of hydrocarbons (HC), a range of wavelengths of, for example, 3.3 μm is chosen. Both the infrared radiation sources 3, 4 and the infrared radiation reception unit 5 NDIR gas sensor device 1 are connected to a control and evaluation system 7. In this control and evaluation system 7, the target gas concentration can be calculated on the basis of a detection signal which is applied by the infrared radiation receiving unit 5 to the control and evaluation system 7 On the other hand, the control and evaluation system 7 of the NDIR gas sensor device 1 makes it possible to operate the infrared radiation sources 3 , 4 of the latter with different powers.
    [0017] In the exemplary embodiment shown, the control and evaluation system 7 of the NDIR gas sensor device 1 is further connected to an alarm system 8 and to a ventilation device 9. In the case where the calculated value in the control and evaluation system 7 for the target gas concentration exceeds a predefined limit value, the control and evaluation system 7 triggers the alarm system 8, so that the risks for persons lying in in the space or in the cockpit 2 can be reduced or discarded. In addition to or instead of this, the control and evaluation system 7 can also start the ventilation device 9 when the limit value is reached or exceeded, and in this case the operation of the ventilation device 9 makes it possible to to bring the concentration of target gas into the space or the passenger compartment into a range of acceptable values 2. On the other hand, a temperature sensor 10 is connected to the control and evaluation system 7 of the NDIR gas sensor device. This sensor 10 measures the temperature in the space or the passenger compartment 2. The triggering of the alarm system 8 and / or the ventilation device 9 by the control and evaluation system 7 can be linked to a value temperature threshold set. Thus, in a parked vehicle, the alarm installation 8 or the ventilation device 9 can for example be triggered only if a defined minimum temperature level is reached or exceeded. In the exemplary embodiment shown, the NDIR gas sensor device 1 shown in the figure can work in three different modes of operation. In a first mode of operation, the NDIR gas sensor device 1 works with a relatively low power consumption. In this first mode of operation, a reduced signal quality is voluntarily accepted and consequently a relatively high resolution, precision and signal / noise ratio are dispensed with. The priority of this first mode of operation is the relatively low energy consumption. In this first mode of operation, the second source of infrared radiation 4 operates with low radiated power. In a second mode, the operation of the NDIR gas sensor device 1 is accompanied by a relatively high energy consumption. In this second mode of operation, priority is given to a relatively high signal quality, with high resolution, precision, and signal-to-noise ratio. In this second mode of operation, the first source of infrared radiation 3 operates with a high radiated power. In a third mode of operation, the operation of the NDIR gas sensor device 1 is also accompanied by a relatively high energy consumption. In this third mode of operation, priority is also given to relatively high signal quality, with high resolution, accuracy, and signal-to-noise ratio. In this third mode of operation, the second source of infrared radiation 4 operates with a radiated power which is high compared to that of the first mode of operation. According to the Beer-Lambert law, the sensitivity of the NDIR gas sensor device 1 in accordance with the invention described above depends inter alia on the average length of the optical path between the infrared radiation sources 3, 4 and the unit. The longer path length implies higher sensitivity and therefore higher resolution and accuracy for relatively low target gas concentrations. On the other hand, in the presence of very high concentrations of the target gas, a long optical path has the effect that the gas sensor device reaches a state of saturation. Despite a concentration that continues to increase, it is no longer possible to measure with a reasonable economic investment a change in the infrared radiation energy received by the infrared radiation receiving unit. For this reason, for high concentrations of the target gas, a relatively short optical path between the first source of infrared radiation 3 and the infrared radiation receiving unit 5 is used for measurement. Now, this relatively short optical path length is in turn accompanied by a relatively low sensitivity and therefore a very low resolution of the detection signal for relatively low concentrations of the target gas.
    [0018] As a result, the first 3 and the second source of infrared radiation 4 are provided in the case of the NDIR gas sensor device 1 according to the invention, and as explained above, the first source of infrared radiation 3 is arranged to a relatively small distance and the second source of infrared radiation 4 is disposed at a relatively large distance from the radiation receiving unit 5. In the first operating mode of the NDIR gas sensor device, the second source of infrared radiation 4, which has a large distance from the infrared radiation receiving unit 5, is fed with low power by the control and evaluation system 7. Thanks to the greater sensitivity due to the long optical path between the second source of infrared radiation 4 and the infrared radiation receiving unit 5, it is possible to perform reliable detection of C leaks O2, without the NDIR gas sensor device 1 having a high energy consumption. In the second mode of operation, the first source of infrared radiation 3 is supplied with high power by the control and evaluation system 7. Since this provides a high quality of the signal, with a high resolution, a high accuracy and a high signal-to-noise ratio, this operating mode makes it easy to detect a low concentration of target gas. Thus, with the help of the NDIR gas sensor device 1, it is possible to detect whether a living being is in a parked vehicle. This application requires a high resolution of the detection signal and a high accuracy of the CO2 concentration in the range of up to 2000 ppm. In connection with a maximum permissible temperature level which is recorded in the control and evaluation system 7, it is possible to trigger the alarm system 8 or the ventilation device 9, whenever the gas sensor device NDIR 1 detects that a living being is in a parked vehicle and that the temperature in the passenger compartment 2 of the vehicle exceeds a critical level. A sleeping infant breathes at about 20 breaths per minute. The volume of air is about 100 ml. Therefore, an infant rejects about 0.08 1 of CO2 per minute, which is about 5 1 per hour. When the passenger compartment has a volume of approximately 5 m3, the sleeping infant caused an increase in the CO2 concentration of 0.1% in volume after one hour. If it is assumed that in full sunlight a parked motor vehicle reaches critical temperatures in excess of 60 degrees C in the passenger compartment within half an hour, the NDIR gas sensor system must be capable of reliably detecting an increase of 0.05% by volume (500 ppm) of the CO2 concentration. For this, the third mode of operation is in principle advantageous, wherein the second source of infrared radiation 4, which is at a great distance from the infrared radiation receiving unit 5, is fed with a high power. However, as the monitoring of the presence of a living being in the passenger compartment 2 of a vehicle takes place only when the vehicle is parked, it must be taken into account that the NDIR gas sensor device 1 must be used with low power consumption. Correspondingly, after parking the vehicle, the NDIR gas sensor device is activated in the third mode of operation for a predefined period of time, for example for about 30 minutes. If, during this period of time, the measured increase in the CO2 concentration is lower than a predefined threshold value, the NDIR gas sensor device 1 goes to the first operating mode. It is also possible to operate the NDIR gas sensor device 1 intermittently between the first and the third mode of operation for a predetermined period of time after the vehicle is parked. The ratio between the two operating modes can be freely programmed. For example, the NDIR gas sensor device can perform one measurement per minute in the first mode of operation. This measurement is used to detect CO2 leaks. For the period of one hour after parking the vehicle, one in ten measurements is performed in the third mode of operation. This measurement is then used to detect the presence of living beings in the passenger compartment of the vehicle.
    [0019] This method ensures rapid detection of CO2 leaks by the corresponding measurement performed every minute. On the other hand, we obtain a reliable detection of the presence of living beings in the cabin 2 of the vehicle, with a sufficient interval in time. Conveniently, the NDIR gas sensor device 1 can cease CO2 monitoring, if, within a preprogrammable time period, can be recorded in the control and evaluation system 7, the increase in the CO2 concentration is below the limit defined for the detection of living beings. The corresponding decision can be taken internally, that is to say in the NDIR gas sensor device 1, or by an external control device. For the detection of CO2 leaks, it is possible, in the first operating mode of the NDIR gas sensor device, to save in the control and evaluation system 7 a first predefinable threshold value of the target gas concentration. This first threshold value of the target gas concentration is set at such a low level, compared to an equally predefined alarm threshold value, that because of the difference between this first threshold value and the alarm threshold value, it is guaranteed in all cases that the switching from the first operating mode to the second operating mode takes place well before the alarm threshold value of the target gas concentration is reached. If, in the first mode of operation of the NDIR gas sensor device 1, the control and evaluation system 7 thereof detects that the target gas concentration has reached or exceeded the first predefinable threshold value, the control system and evaluation 7 switches the NDIR gas sensor device 1 from the first mode of operation to the second mode of operation. The first source of infrared radiation 3 is then supplied with a relatively high radiated power in the second mode of operation of the NDIR gas sensor device 1. Thus, it is ensured that the quality of the detection signal sent by the radiation reception unit The infrared 5 to the control and evaluation system 7 is substantially improved in the second mode of operation, and this already in a range of the target gas concentration which is very far from a risky range. If, in the second mode of operation of the NDIR gas sensor device 1, the target gas concentration in the space or the passenger compartment increases to reach or exceed the predefined alarm threshold value, the control system and the evaluation 7 triggers the alarm installation, and at the same time it is possible to activate the ventilation device 9 which ensures by the ventilation of the space or the passenger compartment 2 that the concentration of target gas does not increase further. If a third threshold value, which may also be predefined for the target gas concentration and can be stored in the control and evaluation system 7, is exceeded downward, while the NDIR gas sensor device 1 is in the In the second mode of operation, the control and evaluation system 7 switches the gas sensor device NDIR 1 back to the first mode of operation.
    [0020] If, after a switching of the NDIR gas sensor device 1 in its second operating mode, the predefined alarm threshold value recorded in the control and evaluation system 7 is not reached, a new first threshold value is calculated, which is greater than the old first threshold value; this new first threshold value is recorded in the control and evaluation system 7, and then the control and evaluation system 7 switches the gas sensor device NDIR 1 back to the first mode of operation. Thus, this adaptation or increase of the first threshold value, which is provided for the switching of the NDIR gas sensor device 1 from its first to its second operating mode, prevents the NDIR gas sensor device 1 from changing constantly between the first and second operating modes. and the second mode of operation.
    [0021] During the operation of the NDIR gas sensor device 1 described above, it is obtained that during most of its service life its radiation device, consisting of the sources of infrared radiation 3, 4, can operate with very low power requirements. The radiated power of the infrared radiation device 3, 4 of the NDIR gas sensor device 1 is increased only in the relatively rare cases where the first predefinable threshold value of the target gas concentration is exceeded. Only in these cases is the higher quality detection signal needed, knowing that this higher signal quality is provided by the then much higher radiated power of the first source of infrared radiation 3 of the NDIR gas sensor device 1.
    权利要求:
    Claims (17)
    [0001]
    REVENDICATIONS1. A gas sensor device for measuring a target gas concentration, comprising: a radiation device (3, 4) for emitting radiation energy through a space (2) containing the target gas; a radiation receiving device (5) for detecting the radiation energy emitted by the radiation device (3, 4); a filter device (6) which is associated with the radiation receiving device (5) and passes radiation of a wavelength range corresponding to the target gas; and a control and evaluation system (7) which is connected to the radiation receiving device (5) and which calculates the target gas concentration on the basis of a detection signal applied to the control system and evaluation (7) by the radiation receiving device (5), characterized in that the gas sensor device (1) is designed as a non-dispersive infrared spectroscopy (NDIR) gas sensor device (1), in that the radiation device (3, 4) of the NDIR gas sensor device (1) has at least two sources of infrared radiation (3, 4), and that each of the infrared radiation sources (3, 4) is of at least two of the radiation device (3, 4) of the NDIR gas sensor device (1) is arranged at a different optical distance from the radiation receiving device (3) as an infrared radiation receiving device ( 5), the NDIR gas sensor device (1).
    [0002]
    A gas sensor device for measuring a target gas concentration, comprising: a radiation device for emitting radiation energy through a space containing the target gas; a radiation receiver device for detecting the radiation energy emitted by the radiation device; a filter device which is associated with the radiation receiving device and passes radiation of a wavelength range corresponding to the target gas; and a control and evaluation system which is connected to the radiation sink device and which calculates the target gas concentration based on a detection signal applied to the control and evaluation system by the radiation receiver device characterized in that the gas sensor device is constructed as a non-dispersive infrared spectroscopy (NDIR) gas sensor device, in that the radiation receiver device of the NDIR gas sensor device has at least two reception units of infrared radiation, and in that each of the at least two infrared radiation receiving units of the radiation receiving device of the NDIR gas sensor device is disposed at a different optical distance from the radiation device, realized as a source of infrared radiation, the NDIR gas sensor device.
    [0003]
    A gas sensor device according to claim 1 or 2, characterized in that the optical distance between a first infrared radiation source (3) and the infrared radiation receiving unit (5) or between the infrared radiation source and a first infrared radiation receiving unit is relatively small, and the optical distance between a second infrared radiation source (4) and the infrared radiation receiving unit (5) or between the infrared radiation source and a second infrared radiation source Infrared radiation reception is relatively large.
    [0004]
    4. gas sensor device according to one of claims 1 to 3, characterized in that at least the second source of infrared radiation, preferably each source of infrared radiation (3, 4), can be supplied with different powers.
    [0005]
    A gas sensor device according to claim 1, 2 or 4, comprising a first operating mode and a second operating mode, wherein, in the first operating mode, the second infrared radiation source (4) is supplied with a low power, andin which, in the second mode of operation, the first source of infrared radiation (3) is fed with a higher power compared to the power of the. second source (4) in the first mode of operation.
    [0006]
    Gas sensor device according to claim 5, characterized in that it can operate in a third mode of operation, in which the second source of infrared radiation (4) is fed with a higher power, compared to that of the first operating mode.
    [0007]
    7. A gas sensor device according to claim 5 or 6, characterized in that it can be switched from the first or the second mode of operation to the second or the first mode of operation by its control and evaluation system (7) , based on detection signals collected therein when the NDIR gas sensor device (1) is in the first or second mode of operation.
    [0008]
    8. Gas sensor device according to claim 7, characterized in that it can be switched from the first to the second mode of operation by its control and evaluation system (7), if it is detected in the control system. and evaluating (7) that a predefined threshold value, for example an absolute value or a gradient, of the target gas concentration is reached or exceeded.
    [0009]
    9. Gas sensor device according to one of claims 5 to 8, characterized in that its control and evaluation system (7) allows to bring the NDIR gas sensor device (1) from its second to its first mode. of operation, if it is detected in the second mode of operation of the NDIR gas sensor device (1), by means of the control and evaluation system (7), that the threshold value set for switching from the first to the second operating mode of the NDIR gas sensor device (1), or another threshold value set for switching from the second to the first operating mode, is reached or exceeded downwards.
    [0010]
    10. Gas sensor device according to one of claims 5 to 9, characterized in that its control and evaluation system (7) makes it possible to adapt the predefinable threshold value for the first operating mode, in order to switching to the second operating mode, or the predefinable threshold value for the second operating mode, for switching to the first operating mode of the NDIR gas sensor device (1), if, in the second operating mode of the device NDIR gas sensor (1), it is detected by means of the control and evaluation system (7) that the predefinable alarm threshold value is not reached for a predefinable period of time from the switching of the first in the second mode of operation of the NDIR gas sensor device (1).
    [0011]
    11. Gas sensor device according to one of claims 6 to 10, characterized in that after parking or stopping a motor vehicle equipped with this device to monitor its passenger compartment (2), said device can operate for a predefinable period of time to change intermittently, with an adjustable ratio, between its first mode of operation and its third mode of operation.
    [0012]
    Gas sensor device according to one of Claims 5 to 11, characterized in that its control and evaluation system (7) makes it possible to switch on an alarm system (8) and / or a control device. ventilation (9) or the like, if, in the second and / or third mode of operation of the NDIR gas sensor device (1), it is detected in the control and evaluation system (7) thereof, a predefined alarm threshold value is reached or exceeded.
    [0013]
    Gas sensor device according to one of Claims 1 to 12, characterized in that in the third mode of operation the alarm system (8) and / or the ventilation device (9) can not be triggered only if a temperature sensor (10) detects the exceeding of a predefined temperature threshold value and transmits it to the control and evaluation system (7).
    [0014]
    14. A gas sensor device according to one of claims 1 to 13, characterized in that it can be automatically adjusted, by means of its control system and evaluation (7), according to an algorithm defined by laps of predefined time and threshold values and predefinable alarm values for detection signals.
    [0015]
    15. Use of a gas sensor device according to one of claims 1 to 14, for measuring the concentration of CO2 or the concentration of HC in the passenger compartment (2) of a motor vehicle.
    [0016]
    16. A method for operating an NDIR gas sensor device (1), preferably an NDIR gas sensor device (1) according to one of claims 1 to 14, wherein there is provided at least two modes of operation of the device. NDIR gas sensor (1), and according to which, in each operating mode of the NDIR gas sensor device (1), infrared radiation sources (3, 4) of the NDIR gas sensor device (1) are supplied with different powers, knowing that in a first mode of operation a source of infrared radiation (4) is fed with a low power, and in a second mode of operation a source of infrared radiation (3) is fed with a high power.
    [0017]
    17. The method of claim 16, wherein a switching of the BLACK gas sensor device (1) from one operating mode to another takes place, if preset threshold values are reached or exceeded downwards or upwards, and / or predefinable periods of time are exceeded.
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    同族专利:
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    优先权:
    申请号 | 申请日 | 专利标题
    DE102014010712.4|2014-07-19|
    DE102014010712.4A|DE102014010712A1|2014-07-19|2014-07-19|"Gas sensor arrangement for measuring a target gas concentration"|
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