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EP-4119924-B1 - PARTICULATE MATTER SENSOR DEVICE

EP4119924B1EP 4119924 B1EP4119924 B1EP 4119924B1EP-4119924-B1

Inventors

  • Gütle, Frank
  • Leidenberger, Ulrich
  • MRCARICA, ZELJKO
  • KOSTNER, Stefan
  • THIELE, STEFAN

Dates

Publication Date
20260506
Application Date
20180313

Claims (15)

  1. A particulate matter sensor device (1) for detecting and/or characterising particulate matter in a flow (20) of an aerosol sample guided through the particulate matter sensor device (1), comprising: - an enclosure (21), the enclosure (21) comprising a flow inlet (11) and a flow outlet (12), and the enclosure (21) being arranged and configured for defining a flow channel (2) for guiding the flow (20) of the aerosol sample through the particulate matter sensor device (1) from the flow inlet (11) to the flow outlet (12); - a radiation source (3) arranged and configured to emit radiation at least partially into the flow channel (2) for interaction of the radiation with at least some of the particulate matter in the flow (20) of the aerosol sample; - a radiation detector (4) arranged and configured to detect at least part of said radiation after interaction with the particulate matter; and - a flow modifying device (511, 511a, 512, 513, 514; 521) arranged closely upstream of the radiation detector (4) and/or of the radiation source (3), and configured to at least locally modify the flow of the aerosol sample, the flow modifying device (511, 511a, 512, 513, 514; 521) comprising or consisting of at least one additional flow opening (511, 511a, 512, 513, 514) for creating an additional flow into the flow channel (2), wherein the at least one additional flow opening (511, 511a, 512, 513, 514) is arranged upstream of the radiation detector (4) with respect to the flow (20) of the aerosol sample, and wherein the at least one additional flow opening (511, 511a, 512, 513, 514) is arranged and configured to create its additional flow in such a manner that the additional flow sheaths the radiation detector (4), the radiation detector (4) being disposed in a flow path of the additional flow, characterised in that the at least one additional flow opening (511, 511a, 512, 513, 514) is arranged in a wall section that delimits the flow channel (2) radially with respect to a longitudinal axis (L) that corresponds to the flow direction of the flow (20) of the aerosol sample.
  2. The particulate matter sensor device (1) according to claim 1, wherein the additional flow is sheet-like, and wherein the sheet-like additional flow covers the radiation detector (4).
  3. The particulate matter sensor device (1) according to claim 2, wherein the at least one additional flow opening (511, 511a, 512, 513, 514) is slit-like for producing the sheet-like additional flow and extends in circumferential direction with respect to the cross-section of the flow channel (2).
  4. The particulate matter sensor device (1) according to any one of the preceding claims, wherein the flow modifying device (511, 511a, 512, 513, 514, 521) further comprises a constriction (521) in or of the flow channel (2), the constriction (521) being configured to direct at least part of the flow of the aerosol sample (2) away from a detection area (40) of the detector (4) and/or away from an emitting area (300) of the radiation source (3); and wherein said constriction (521) preferably is arranged and configured such that a constriction maximum (525) of said constriction (521) is located at a second distance (d 3 ,d 4 ) of less than 5 millimeters, preferably less than 3 millimeters, upstream of the radiation detector (4) and/or the radiation source (3) with respect to the flow of the aerosol sample (2), and/or wherein the at least one additional flow opening is preferably arranged upstream or downstream of a constriction maximum (525) of the constriction (521) with respect to the flow of the aerosol sample (2).
  5. The particulate matter sensor device (1) according to claim 4, wherein the constriction (521) comprises a ramp-like element, and wherein the at least one additional flow opening (511, 511a; 512, 513, 514) is arranged between the ramp-like element (521) and the radiation detector (4), or wherein the ramp-like element is arranged between the at least one additional flow opening (511, 511a; 512, 513, 514) and the radiation detector (4).
  6. The particulate matter sensor device (1) according to claim 5, wherein the constriction (521) extends over a constriction region (524), and wherein the radiation detector (4) or the radiation source (3) is arranged in a constriction recess (523) that is arranged in said constriction region (524) and that extends radially into said constriction (521), said constriction recess preferably having a diameter (D PD ) of 0.5 millimeters to 5 millimeters.
  7. The particulate matter sensor device (1) according to any one of claims 4-6, wherein the constriction (521) constricts the flow channel (2) in a continuous manner, extending over a constriction region (524) such that a clear width of the flow channel in the constriction region both before and after the constriction maximum (525) changes monotonically or strictly monotonically, and wherein a distance (d 3 ) between the detection area (40) and the constriction maximum (525) is preferably less than two thirds of a downstream half-length (c 0 ) of the constriction (521).
  8. The particulate matter sensor device (1) according to any one of the preceding claims, wherein the particulate matter sensor device (1) comprises an environmental sensor (7) for determining at least one environmental parameter, the environmental sensor (7) being disposed in a flow path of the additional flow upstream from the additional flow opening (511, 511a, 512, 513, 514), and wherein the radiation detector (4) is arranged in the flow path of the additional flow downstream from the environmental sensor (7), wherein preferably the environmental sensor (7) is configured to determine a temperature, a humidity, and/or a concentration of one or more target gases..
  9. The particulate matter sensor device (1) according to any one of the preceding claims, wherein a filter (213) is associated with the at least one additional flow opening (511, 511a, 512, 513, 514) such that the additional flow is a filtered flow.
  10. The particulate matter sensor device (1) according to claim 9, wherein the at least one additional flow opening (511, 511a, 512, 513, 514) is supplied by a gas drawn into the particulate matter sensor device (1) from at least one secondary inlet (13) which is separate from the flow inlet (11).
  11. The particulate matter sensor device (1) according to claim 10, comprising a cover (214) that covers the enclosure (21), wherein the at least one secondary inlet (13) is formed in the cover (214), and wherein the filter (213) is flat and sheet-like, extending parallel to the cover (214), wherein the cover (214) preferably comprises a solid cover plate and a peripheral wall, and wherein a plurality of secondary inlets are preferably formed along the peripheral wall of the cover (214), preferably at regular distances around the peripheral wall of the cover (214).
  12. The particulate matter sensor device (1) according to any one of the preceding claims, wherein the radiation detector (4) is mounted on a circuit board (23), wherein the particulate matter sensor device is configured such that the at least one additional flow, during use, traverses the circuit board (23) through one or more through-holes (231), the feed line thereby including the one or more through-holes (231).
  13. The particulate matter sensor device (1) according to claim 11 in combination with claim 12, wherein the flat, sheet-like filter (213) is arranged between the cover (214) and the circuit board (23) and extends parallel to both the cover (213) and the circuit board (23).
  14. The particulate matter sensor device (1) according to any one of the preceding claims, wherein the at least one flow modifying device (511, 511a, 512, 513, 514) is configured for introducing into said flow channel (2) said at least one additional flow such that a magnitude of said at least one additional flow, in total, equals to or is less than 30 percent, preferably less than 20 percent, of a magnitude of the flow (20) of the aerosol sample through the flow channel (2) upstream said at least one flow modifying device (511, 511a, 512, 513, 514).
  15. A method for detecting and/or characterising particulate matter in a flow (20) of an aerosol sample, comprising the steps of: - guiding the flow (20) of the aerosol sample through the flow channel (2) of the particulate matter sensor device (1) according to any one of the preceding claims; - emitting radiation into the flow channel (2) from the radiation source (3) for interaction with the particulate matter in the flow (20) of the aerosol sample; and - detecting, by means of the radiation detector (4), at least part of said radiation after interaction with the particulate matter.

Description

TECHNICAL FIELD The present invention relates to a particulate matter sensor device, in particular to an optical particulate matter sensor device, for ascertaining a number concentration and/or a mass concentration of particulate matter in air. PRIOR ART WO 2017/054098 A1 discloses a low cost optical particle sensor for determining a particle concentration. US 2014/0247450 A1 discloses a system and a method of measuring a particle's size in a select aerosol using the optical diameter of the particle to perform a mobility and/or aerodynamic diameter conversion without any knowledge about the particle's shape and its optical properties in the aerosol being characterized. It discloses the use of a substantially clean flow of gas that shrouds or sheaths the aerosol flow. The cleansed sheath flow helps contain particulates within the core of the aerosol flow as it passes through the optics chamber, thereby mitigating against particulate contamination of the optics chamber and appurtenances therein. US 2009/0039249 A1 discloses an apparatus for estimating size segregated aerosol mass concentration. An incoming stream is split into a sheath flow stream and an aerosol flow stream. The sheath flow stream is diverted to a sheath flow conditioning loop that may include a filtration device and a flow measuring device. The filtration device of the sheath flow conditioning loop removes particulates from the sheath flow stream to provide a substantially clean flow of gas that shrouds or sheaths the aerosol flow. The cleansed sheath flow helps contain particulates within the core of the aerosol flow as it passes through the optics chamber, thereby mitigating against particulate contamination of the optics chamber and appurtenances therein. The aerosol flow stream is passed through an inlet nozzle to an optics chamber that includes a viewing or interrogation volume. US 2016/0077218 A1 discloses a detection device that is formed in a body of semiconductor material having a first face, a second face, and a cavity. A detection area is formed in the cavity, and a gas pump is integrated in the body and configured to force movement of gas towards the detection area. A detection system of an optical type or a detector of alpha particles is arranged at least in part in the detection area. US 6,159,739 discloses a sheath flow module made from a first plate of material having formed therein a laminar fluid flow channel; at least two inlets, each inlet joining the laminar flow channel at a junction, the first inlet junction being wider than the second inlet junction, and an outlet from the flow channel. A second plate, e.g. a transparent cover plate, seals the module and allows for optical measurements. A first inlet allows for introduction of a first fluid into the flow channel. The first fluid is the sheath fluid. A second inlet allows for introduction of a second fluid into the sheath fluid while it is flowing through the flow channel. The second fluid is the center fluid. Because the second inlet junction is narrower than the first inlet junction, the center fluid becomes surrounded on both sides by the sheath fluid. US 8,941,826 B2 discloses a microfluidic device comprising inlets for a sample flow and an out-of-plane focusing sheath flow, and a curved channel section configured to receive the sample flow and out-of-plane focusing sheath and to provide hydrodynamic focusing of the sample flow in an out-of-plane direction, the out-of-plane direction being normal to a plane including the curved channel. US 2003/0235926 A1 discloses a flow-through monitor for detecting molecular contamination within a fluid flow. The monitor has a diffusion chamber having an inlet port and an outlet port, and a structure for supporting a fluid flow from the inlet port to the outlet port. The structure includes a flow gap causing a diffusion of molecular contaminants into the diffusion chamber, while substantially preventing, for a rate of the fluid flow above a predetermined magnitude, particulate contaminants within the fluid from entering the diffusion chamber. US 2014/0273193 A1 discloses electrokinetic microfluidic cytometers useful for detecting and/or sorting fluid-borne particles. The electrokinetic microfluidic flow cytometer apparatus comprises a substrate having a microchannel formed therein, a particle-sensing gate that reduces the cross-sectional area of a portion of the microchannel, a pair of signal- and noise-detection electrodes, and a particle-detection circuit that is electrically connected to the signal- and noise-detection electrodes and is configured to generate a particle-detection signal responsive to differences in resistivity across the particle-sensing gate. JP H01-265137 discloses a particle detector. Sample air containing particles is blown out of an internal nozzle. Clean air is supplied between the internal nozzle and an external nozzle to create a sheath flow around the sample flow. SUMMARY OF THE INVENTION It is an ob