RUSS SENSOR AND METHOD FOR DETECTING EXHAUST PINE DUST

Abstract

Soot sensor (106), comprising: a curved sensor surface (200) on which interlocking electrodes (202) with different voltages are arranged; an inlet (208) arranged to capture an exhaust gas sample stream (210) from an exhaust gas stream (212); and a channel (240) formed to direct the exhaust gas sample stream (210) to the curved sensor surface (200) in a direction which forms an acute angle (216) with a line (218) which is perpendicular to the curved sensor surface (200), and wherein the channel (240) includes a first channel (241) and a second channel (243), wherein: the first channel (241) is positioned transversely to the exhaust gas stream (212), with two or more openings (208) on an upstream side (248) thereof to allow exhaust gas into the first channel (241) at separate and different radial locations in the exhaust gas stream (212), wherein the second channel (243) is toroidal and flow-connected to the first channel (241), and wherein the curved sensor surface (200) is arranged inside the second channel (243).

Description

AREA

[0001] The present description relates generally to the design and use of resistance-based particulate matter sensors in an exhaust gas stream, and in particular to a soot sensor with a curved sensor surface on which interlocking electrodes with different voltages are arranged, as well as a method for determining a soot concentration value in an exhaust gas stream. STATE OF THE ART / BRIEF OVERVIEW

[0002] Diesel combustion can produce emissions, including particulate matter (PM). PM can consist of diesel soot and aerosols such as ash particles, metallic debris, sulfates, and silicates. When released into the atmosphere, PM can take the form of individual particles or chain-like aggregates, mostly in the invisible submicrometer range of 100 nanometers. Various technologies have been developed to identify and filter out PM from exhaust gases before they are released into the atmosphere.

[0003] For example, soot sensors or PM sensors can be used in vehicles with an internal combustion engine. A PM sensor can be located upstream and / or downstream of a diesel particulate filter (DPF) and can be used to detect PM loading on the filter and diagnose the DPF's operation. The PM sensor can detect particulate matter or soot loading based on a correlation between a measured change in electrical conductivity (or electrical resistance) between a pair of thin electrodes on a flat substrate surface of the sensor and the amount of PM deposited between the measured electrodes. In particular, the measured conductivity provides a measure of soot accumulation.

[0004] An exemplary PM sensor is shown by Goulette et al. in US 2015 / 0153249A1. In this design, a conductive material arranged on a substrate has a pattern that forms interlocking "comb" electrodes of a PM sensor. When a voltage is applied across the electrodes, soot particles accumulate on or near the surface of the substrate between the electrodes.

[0005] Furthermore, DE 10 2017 111 507 A1, which represents the prior art after publication, shows a soot sensor with a curved sensor surface on which interlocking

[0006] Electrodes with different voltages are arranged, along with an inlet for capturing an exhaust gas sample stream and first and second channels that guide the sample stream to the curved sensor surface. Another soot sensor is disclosed in German patent application DE 10 2016 102 597 A1, in which an outer pipe positioned transversely in the exhaust gas stream has a plurality of intake openings in the upstream sector, and an inner pipe positioned in this outer pipe has its intake openings in a downstream sector. Further soot sensors are known from patent applications US 4 656 832 A and DE 10 2015 118 457 A1.

[0007] The inventors have identified potential problems with such systems. For example, with these PM sensors, only a small fraction of the PM in the incoming exhaust gas is exposed to the electrostatic forces exerted between the electrodes and is collected on the electrodes formed on the sensor surface, resulting in low sensor sensitivity. Furthermore, even the fraction of PM that collects on the surface may not be uniform due to a tendency in the flow distribution across the sensor surface. It is possible that the PM tends to accumulate mainly or predominantly on one inlet side of the sensor, resulting in a low and / or uneven soot load. The uneven deposition of PM on the sensor surface can further exacerbate the problem of low sensor sensitivity.

[0008] The present invention therefore aims to provide an improved soot sensor and an improved method for determining the soot concentration value in an exhaust gas stream of the type mentioned, which achieve high sensitivity and avoid uneven soot loading on the sensor surface.

[0009] According to the invention, the aforementioned problem is solved by a soot sensor according to claim 1 and a method according to claim 9. Preferred embodiments of the invention are the subject of the dependent claims.

[0010] The aforementioned problems are addressed by a soot sensor, including: a curved sensor surface on which interlocking electrodes with different voltages are arranged. An inlet can be provided to capture an exhaust gas sample stream from a diesel engine. A channel can be formed to direct the sample stream to the curved sensor surface in a direction that forms an acute angle with a line perpendicular to the curved sensor surface. In this way, an effective measurement of PM concentration can be achieved. Furthermore, this design allows for better and more uniform soot capture, increasing the sensor's sensitivity and reliability.

[0011] Overall, these properties of the sensor assembly can lead to a more accurate output from the sensor assembly, thereby increasing the accuracy in estimating particle loading on a particle filter.

[0012] It is understood that the above summary is provided to present, in a simplified form, a selection of concepts that are described in more detail in the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a schematic representation of an engine and an associated fine dust (PM) sensor positioned in an exhaust stream. Fig. Figure 2 is a side cross-sectional view of an exemplary PM sensor according to the present disclosure. Fig. 3A and Fig. 3B is each a side and end view of a sample flow direction within the in Fig. 2 PM sensors shown according to the present disclosure. Fig. Figure 4 is an end cross-sectional view of the exemplary PM sensor made of Fig. 2, in which additional details are illustrated, according to the present revelation. Fig. Figure 5 is a partial, perspective sectional view of a channel with a sensor surface arranged therein according to the present disclosure. Fig. Figure 6 is a perspective view of a cylindrical sensor surface on which interlocking electrodes are arranged and which has a cylindrical shape according to the disclosure. Fig. Figure 7 is a perspective view of a curvilinear sensor surface shaped as a truncated cone or conical section, according to the disclosure. Fig. Figure 8 is a perspective view of an exemplary sensor according to the revelation. Fig. Figure 9 is a cross-sectional view through an exemplary channel, which is considered to be the one in Fig. The channel shown in section 8 can be considered similar, according to the revelation. Fig. 9A, Fig. 9B and Fig. 9C are each cross-sectional views, each along lines AA, BB, and CC in Fig. 9. Fig. Figure 10 is a detailed view of a curvilinear sensor surface according to the disclosure. Fig. Figures 11 and 12 are graphical representations showing an exemplary filter loading and filter regeneration process according to the present disclosure. DETAILED DESCRIPTION

[0013] The following description relates to embodiments of a particulate matter (PM) sensor, including systems and methods for detecting particulate matter (PM) in an exhaust stream of an engine system, such as the one described in Fig. The engine system shown in Figure 1. Embodiments may include a controller 12, which may be configured to execute one or more control routines to assist in or perform various engine operations, including one or more routines for accumulating exhaust PM via electrodes formed according to the present disclosure. Effective and well-distributed PM accumulation by the embodiments disclosed herein may result in a more accurate PM sensor output, thereby increasing the accuracy in estimating particle loading on a particulate filter and enhancing the monitoring efficiency of the PM filter located upstream of the PM sensor. Furthermore, by enabling more accurate diagnostics of the particulate filter, exhaust emission compliance may be improved. This may reduce warranty costs associated with replacing functional particulate filters.Furthermore, exhaust emissions can be improved and the service life of exhaust components extended.

[0014] Fig. Figure 1 shows a schematic representation of a vehicle system 6. The vehicle system includes an engine system 8. The engine system 8 can include an engine 10 with a plurality of cylinders 30. The engine 10 includes an engine intake element 23 and an engine exhaust element 25. The engine intake element 23 can include a throttle 62, which is flow-connected to the engine intake manifold 44 via an intake passage 42. The engine exhaust element 25 includes an exhaust manifold 48, which leads to an exhaust passage 35 that discharges exhaust gas into the atmosphere. The throttle 62 can be located in the intake passage 42 of a booster device, such as downstream of a turbocharger (not shown) and upstream of an aftercooler (not shown). When integrated, the aftercooler can be configured to reduce the temperature of the intake air compressed by the booster device.

[0015] The engine exhaust element 25 can include one or more emission-reducing devices 70, which may be mounted in a closely coupled position within the exhaust element. One or more emission-reducing devices may include a three-way catalytic converter, lean NOx filter, SCR catalyst, etc. The engine exhaust element 25 can also include a diesel particulate filter (DPF) 102, which preliminarily filters PM from incoming gases upstream of an emission-reducing device 70. In a large example, as shown, the DPF 102 is a diesel particulate retention system. The DPF 102 may have a monolithic structure, for example, made of cordierite or silicon carbide, with a multitude of channels inside to filter particulate matter from the diesel exhaust.Exhaust gas, from which PM has been filtered out after passing through the DPF 102, can be measured in or with a particulate matter (PM) sensor 106 and further processed in an emission-reducing device 70 and released into the atmosphere via the exhaust passage 35. In the illustrated example, the PM sensor 106 can be a resistance sensor that can be configured to estimate the filtration efficiency of the DPF 102 based on a change in the conductivity measured across the electrodes of the PM sensor 106.

[0016] The vehicle system 6 may further include a control system 14. The control system 14 is shown to receive information from a variety of sensors 16 and send control signals to a variety of actuators 81. As an example, the sensors 16 may include an exhaust gas flow sensor 126 configured to measure the flow rate of exhaust gas through the exhaust passage 35, an exhaust gas sensor (located in the exhaust manifold 48), a temperature sensor 128, a pressure sensor 129 (downstream of the emission control device 70), and a PM sensor 106. Other sensors, such as additional pressure, temperature, air / fuel ratio, exhaust gas flow, and composition sensors, may be coupled at various points in the vehicle system 6.As another example, the actuators 81 can include fuel injectors 66, throttle 62, DPF valves for controlling filter regeneration (not shown), a PM sensor opening controlling the engine actuator (e.g. a control opening of a valve or disc in an inlet of the PM sensor 106), etc.

[0017] The many exemplary actuators 81 can include one or more switches coupled to PM measuring circuits. The control system 14 can include a controller 12. The controller 12 can be configured with computer-readable instructions stored in non-volatile memory. The controller 12 can receive signals from the various sensors 16, process the signals, and use various actuators 81 to adjust motor operation based on the received signals and the instructions stored in the controller 12's memory.For example, during the operation of the PM sensor 106 to collect soot particles, the controller 12 can send one or more control signals to an electrical circuit to apply a voltage to electrodes of a sensor element 202 of a PM sensor assembly 107 in order to capture the charged particles on the surface of the sensor electrodes 202 of the PM sensor 106 or sensor element.

[0018] As another example, during PM sensor regeneration 106, the controller can send a control signal to a regeneration circuit 198, such as a heating element, to close a switch in the regeneration circuit 198 for a threshold period. This applies a voltage to the regeneration circuit 198, coupled to the electrodes, to heat the electrodes of the PM sensor 106. In this way, the electrodes can be heated to burn off soot particles deposited on the surface of the electrodes 202.

[0019] The embodiments can include one or more curvilinear sensor surfaces 200, which are arranged and shaped such that exhaust gas samples, i.e., sample stream 210, can strike the surface 200 at an acute angle 216 and additionally strike and / or contact the sensor surface 200. In this way, soot present in the exhaust gas sample can effectively come into contact with the sensor surface, for example, as discussed, be electrostatically trapped on the curvilinear sensor surface(s) 200, and PM concentration values ​​can be effectively measured.Furthermore, the incident gas can thus cause a rolling or sliding motion across the sensor surface 200, which can tend to move the sampled gas further along the sensor surface 200, while the continued curvature of the sensor surface 200 can effectively position more sensor electrodes 202 in the path of the flowing exhaust gas. The flowing exhaust gas can, in turn, strike the curved sensor surface 200 at an acute angle further downstream or strike it again. This second or additional acute angle may or may not differ from the first acute angle. In this way, an overall, practically continuous effect of the sample exhaust gas stream can be achieved, with effective impact along a considerable length of the sensor surface 200.

[0020] According to this disclosure, the sensor surface 200 can be curved or shaped in various ways. Some examples are disclosed herein. Fig. Figure 5 is a partial, perspective sectional view of a channel 240 with a sensor surface 200 arranged therein. The sensor surface 200 can be a curvilinear surface, for example shaped like a cylinder or having a cylindrical surface. Fig. Figure 6 is a perspective view of a cylindrical sensor surface on which interlocking, comb-like electrodes 204, 206 are arranged. As illustrated, opposite ends of the curvilinear sensor surface can define circles 242 or ovals of similar or identical size or diameter. Fig. Figure 7 illustrates a curvilinear sensor surface, which can be shaped as a truncated cone or a conical section. In this case, as illustrated, opposite ends of the curvilinear sensor surface can define circles or ovals of similar or identical size or diameter. Fig. Figure 8 illustrates another example, where a frustoconical sensor surface 200 can be arranged in a channel 240 defined between an inner screen 244 and an outer screen 246. Fig. Figure 9 is a cross-sectional view through an exemplary duct 240, or a duct body similar to or the same as duct 240 in Fig. 8 is configured.

[0021] Embodiments can provide a particulate matter sensor 106 or a soot sensor 106, which may include a curved sensor surface 200 on which interlocking electrodes 202 can be arranged. The interlocking electrodes 202 can be held at or chargeable with different voltages. For example, a first set of comb-like electrodes 204 can be charged with a relatively positive voltage; and a second set of comb-like electrodes 206 can be located between or interlocked with the first set 204. The second set 206 can be charged with a relatively negative voltage. Respective pairs of comb-like prongs can provide a number of oppositely charged elements to detect the presence of particulate matter. For example, the presence of soot, which can come into contact with the gap between the first electrode 204 and the second electrode 206, can change measurable circuit characteristics.

[0022] With at least brief reference to Fig. 10. The soot sensor 106 can include an inlet 208 which is arranged to take a sample stream 210 of exhaust gas from an exhaust gas stream 212 from a diesel engine 10, for example the one in Fig. 1 illustrated motor 10, to capture. A channel 214 can be shaped to direct the sample stream 210 to the curved sensor surface 200 in a direction that forms an acute angle 216 with a line 218 perpendicular to the curved sensor surface 200.

[0023] As discussed above, embodiments can provide sensor surfaces with an advantageous curvilinear shape. In some examples, the curved sensor surface 200 can be cylindrical. In other examples, the curved sensor surface 200 can be frustoconical. Other shapes are possible.

[0024] Embodiments can provide a soot sensor or a fine dust sensor 106, wherein the channel 240 can include a first channel 241 and a second channel 243. Or, for example, a single channel can be considered to comprise two or more channel sections 241, 243. As in Fig. As illustrated in Figures 2-4, the first channel 241 can be positioned transversely to the exhaust gas flow 212, with two or more openings 208 on an upstream side 248 thereof, to admit exhaust gas into the first channel 241 at separate and distinct radial locations in the exhaust gas flow 212, which can pass through an exhaust gas passage 35. The second channel 243 can be toroidal and can be flow-connected to the first channel, wherein the curved sensor surface 200 can be substantially cylindrical and can be arranged within the second channel 243.

[0025] With reference to Fig. 2-4 The PM sensor assembly or PM sensor system 107 can include a vertical tube 280, which can be divided into two flow passages 282, 283 by a vertical bisecting plate 284. The flow inlet holes 208 can be configured along the upstream surface 248 of the upstream half, i.e., as an upstream flow passage 282 of the vertical tube opposite the incoming exhaust gas flow 212. A flow outlet hole 286 can be configured at the lower part of the downstream half of the vertical tube, i.e., as a downstream flow passage 282.

[0026] A horizontal pipe 288 with a horizontal dividing plate 290 for dividing the pipe into two flow passages: a horizontal upper passage 291 and a horizontal lower passage 293. The upstream half of the vertical pipe 280 can be flow-coupled to the lower half of the horizontal pipe 288, and the downstream half of the vertical pipe 280 can be flow-coupled to the upper half of the horizontal pipe 288. No exhaust gas exchange occurs between the two flow passages.

[0027] A circular tube 294 can be shaped as a bisector with an element base (for example, the curvilinear sensor surface 200 discussed herein) to divide the tube 294 into an outer current passage 295 and an inner current passage 296. The outer current passage 295 can be flow-coupled to the upper half 292 of the horizontal tube 288, and the inner current passage 296 can be flow-coupled to the lower half 293 of the horizontal tube 288.

[0028] A communication gap 298 ( Fig. 3B and 4) can be designed on the element base, i.e., the curvilinear surface 200, to allow exhaust gas to flow from the inner pipe half 296 to the outer pipe half 295. A half-disc 300 can be designed and installed to redirect the exhaust gas to flow along the inner pipe half 296. Fig. 3A and Fig. Figure 3B shows an exhaust gas flow sampling direction within system 107.

[0029] Embodiments may include interlocking electrodes 202 on a concave side 250 of the curved sensor surface 200 and further include an electrical circuit, which may be referred to as a regenerative circuit 198, on an opposite side 252 of the curved sensor surface 200, configured for sensor regeneration. The regenerative circuit 198 can heat the sensor surface 200 and burn off any particulate matter that may have accumulated. The regeneration process can initiate and / or terminate a cycle of sensing the amount of particulate matter. A perceptible deviation from repeated and / or predetermined accumulation behavior, as measured by the sensor 106, may indicate a fault, such as a leak, in the upstream filter.

[0030] In some cases, such as in the Fig. As illustrated in Figures 8-9, the channel 240 can be defined between a conical inner screen 244 and an outer screen 246, wherein the inlet 208 represents one or more holes 209 defined by the inner screen 244 on an upstream side 260, and further comprising one or more holes 262 defined by the outer screen 246 at a location of lower static pressure 264 than the location 266 of the one or more holes 209 in the inner screen 244.

[0031] The inner screen 244 can define a passage 268 through a sensor body, with a passage 270 essentially corresponding to the exhaust gas flow 212, and wherein the one or more holes are open towards the passage 268 and angled in a downstream direction. Large water droplets 302 and diesel particles can follow the exhaust gas flow and, for example, move directly through the passage due to their relatively larger size.

[0032] Fig. Figure 10 is a detailed cross-sectional view of a curvilinear sensor 200 according to the present disclosure. The curved sensor surface 200 can bend into the current 210. The interlocking electrodes 202 can be located at different positions relative to an upstream position of the current and / or at different positions perpendicular to the sample current. In this way, different pairs of electrode prongs 204, 206 can be struck by the current 210 at different times and at different sections.

[0033] Various embodiments can provide a method for determining a soot concentration value in an exhaust gas stream. The method can involve collecting two or more exhaust gas stream samples from two or more locations 208 within an exhaust gas stream downstream of a diesel particulate filter 102. The method can also involve guiding the stream samples 210 to a curvilinear sensor surface 200 such that the stream samples 210 are at an acute angle ( Fig. 10) impact the sensor surface 200 with a line 272 that is tangential to a curvature of the curvilinear sensor surface 200. The method can also involve positioning interlocking electrodes transversely to an arc that is congruent to the curvilinear sensor surface 200.

[0034] Various embodiments may involve positioning a first respective pair of oppositely charged interlocking electrodes upstream and longitudinally offset from a second pair of oppositely charged interlocking electrodes with respect to a general flow direction of the guided current samples.

[0035] In some embodiments, collecting the two or more exhaust gas stream samples involves introducing the samples into spaced-apart openings along a first channel that is oriented substantially orthogonally to one direction of the exhaust gas stream. The method may include positioning the curvilinear sensor surface within a toroidal second channel, as well as passing the samples from the first channel through the second channel.

[0036] In some exemplary embodiments, collecting the two or more exhaust gas stream samples may involve introducing the samples through openings defined in a frustoconical inner screen. The method may involve passing the collected samples through a channel defined between the inner screen and an outer screen, and the samples impacting the curvilinear sensor surface, as well as releasing the samples through openings defined by the outer screen. The method may involve recirculating the sample stream to the exhaust gas stream, minus those soot particles captured between the oppositely charged interlocking electrodes.

[0037] Fig. 11 and Fig.Figure 12 are graphical representations illustrating an exemplary filter loading and regeneration process according to the present disclosure. C1 refers to a value that can be measured by the sensor at the beginning of a regeneration cycle; and C0 refers to a value that can be measured by the sensor at the end of a regeneration cycle. The process can be repeated. A time interval can be recorded for each cycle, and a comparison can be made between a previous time interval, t_i_regen, and the current time interval, t_i+1_regen. If a DPF fails after an i. sensor filter regeneration, the soot concentration downstream of the DPF will be much higher, and the calculated time interval between the i. and (i+1) regeneration will be much shorter. A DPF failure can thus be identified if t_i+1_regen < t_i_regen / 2.

[0038] Various embodiments can provide an exhaust gas sensor assembly 107 that includes a channel 240 for conveying two or more exhaust gas stream samples 210 collected from an exhaust gas stream 212. A curved surface 200 can have electrically chargeable conductors 202 positioned on it and shaped and arranged within the channel 240 such that a centerline of the stream of the two or more exhaust gas samples 210 can impinge on the curved surface 200 at an acute angle 216.

[0039] The channel 240 can include two or more channel sections 241, 242, wherein one channel section 243 can be toroidal, and wherein the curved surface 200 can be substantially cylindrical and can be located within the toroidal channel section 243. The toroidal channel section 243 can be arranged outside an exhaust port 35 and arranged substantially coaxially with the central axis of an exhaust port that directs the exhaust flow 212 from a diesel engine 10.

[0040] The channel 240 can include an inner boundary defined by a conical inner shield 244 and an outer boundary formed by a convex outer shield 246. The curved surface 200 with the electrical conductors 202 can be substantially frustoconical and arranged within the channel 240. The curved surface of the outer boundary 246 can be a convex, annular surface extending radially outward and tending to form one or more low-pressure spots 246 on its outer surface. Embodiments can provide a gap 310 between the inner shield 244 and an inner radius of the curved surface 200 to allow gas samples to pass through the channel 240 and exit downstream of the curved surface.

[0041] In some cases, the curved surface 200 can have an arc length of at least 30 degrees. In some cases, the curved surface 200 can have an arc length of more than 180 degrees and can approach 360 degrees. In some cases, the acute angle 216 can be between 1 and 89 degrees. For example, the acute angle 216 can be greater than 5 degrees.

[0042] The technical benefit of using a PM sensor with a curved surface is that the sample stream tends to impinge on the curved sensor surface with both a perpendicular component of displacement towards the sensor surface and a longitudinal component along the surface. This can then tend to move the sampled gas further along the sensor surface and also tend to move more massive components suspended in the sample stream closer to the sensor surface. In this way, both more efficient contact and efficient utilization of the sensor surface area can be achieved.

[0043] It is noted that the exemplary control and estimation routines contained herein can be used with various engine and / or vehicle system configurations. Selected operations of the control methods and routines disclosed herein can be stored as executable instructions in non-volatile memory and can be executed by the control system, including the controller, in combination with various sensors, actuators, and other engine hardware. The specific routines described herein can be implemented using one or more of any number of processing strategies, such as operation-driven, interrupt-driven, multitasking, multi-threading, and similar strategies. Accordingly, the illustrated steps and / or functions can be executed in the illustrated sequence or in parallel, or in some cases, omitted.Similarly, the processing sequence is not necessarily required to achieve the features and benefits described herein, but serves for illustration and description. One or more of the depicted steps, operations, and / or functions can be performed repeatedly, depending on the strategy employed. Furthermore, the described steps, operations, and / or functions can graphically represent code for programming into non-volatile memory of the computer-readable storage medium in the engine control system, wherein the described steps are performed by executing the instructions in a system that includes the various engine hardware components in combination with the electronic control unit.

[0044] The figures show exemplary configurations with the relative positioning of the various components. If the elements are shown in direct contact or directly coupled / connected, then such elements can be described as being in direct contact or directly coupled / connected, at least in one example. Similarly, elements shown adjacent or side by side can each be described as adjacent or side by side, at least in one example. For instance, components that are opposite each other can be described as opposite each other. In another example, elements positioned apart from each other with only a gap and no other components in between can be described accordingly, at least in one example.In yet another example, elements shown above / below each other, on opposite sides of each other, or to the left / right of each other can be described accordingly in relation to one another. Furthermore, as shown in the figures, a topmost element or the highest point of an element can be referred to as the "top" of the component, and the bottommost element or the lowest point of an element can be referred to as the "bottom" of the component, at least in one example. As used here, top / bottom, above / below, and above / below can be relative to a vertical axis of the figures and can be used to describe the positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example.As a further example, the shapes of elements depicted within the figures can be described as having such shapes (e.g., being circular, straight, flat, curved, rounded, beveled, angular, or the like). Furthermore, elements shown as intersecting can be described as intersecting elements or intersecting elements, at least in one example. Additionally, an element shown inside or outside another element can be described accordingly, in one example.

[0045] It is understood that the configurations and routines disclosed herein are exemplary by nature, and that these specific embodiments are not to be considered limiting, as numerous variations are possible. For example, the above technology can be applied not only to the V-4 but also to the V-6, I-4, I-6, V-12, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0046] The following claims highlight in particular certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or an equivalent thereof. Such claims should be understood as including the incorporation of one or more such elements, without requiring or excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, the same, or different in scope from the original claims, are also considered to be included in the subject matter of the present disclosure.

Claims

[1] Soot sensor (106), comprising: a curved sensor surface (200) on which interlocking electrodes (202) with different voltages are arranged; an inlet (208) arranged to capture an exhaust gas sample stream (210) from an exhaust gas stream (212); and a channel (240) formed to direct the exhaust gas sample stream (210) to the curved sensor surface (200) in a direction which forms an acute angle (216) with a line (218) which is perpendicular to the curved sensor surface (200), and wherein the channel (240) includes a first channel (241) and a second channel (243), wherein: the first channel (241) is positioned transversely to the exhaust gas stream (212), with two or more openings (208) on an upstream side (248) thereof to allow exhaust gas into the first channel (241) at separate and different radial locations in the exhaust gas stream (212), wherein the second channel (243) is toroidal and flow-connected to the first channel (241), and wherein the curved sensor surface (200) is arranged inside the second channel (243). [2] Soot sensor (106) according to claim 1, wherein the curved sensor surface (200) is cylindrical. [3] Soot sensor (106) according to claim 1, wherein the curved sensor surface (200) is frustoconical. [4] Soot sensor (106) according to claim 1, wherein the interlocking electrodes (202) are located on a concave side of the curved sensor surface (200), and further comprising an electrical circuit on an opposite side of the curved sensor surface (200) configured for sensor regeneration. [5] Soot sensor (106) according to claim 1, wherein the channel (240) is defined between a conical inner screen (244) and an outer screen (246), wherein the inlet (208) comprises one or more holes (209) defined by the inner screen (244) on the upstream side (248), and further comprising one or more holes (209) defined by the outer screen (246) at a location with lower static pressure than the one or more holes (209) in the inner screen (244). [6] Soot sensor (106) according to claim 5, wherein the inner screen (244) defines a passage through a sensor body substantially corresponding to the exhaust gas flow (212), and wherein the one or more holes (209) are open opposite the passage and angled in a downstream direction. [7] Soot sensor (106) according to claim 1, wherein the curved sensor surface (200) is bent in the direction of flow of the exhaust gas sample stream (210), and wherein the interlocking electrodes (202) are located at different positions in the direction of flow of the exhaust gas sample stream (210). [8] Soot sensor (106) according to claim 7, wherein the interlocking electrodes (202) are also located at different positions transverse to the exhaust gas sample stream (210). [9] Method for determining a soot concentration value in an exhaust gas stream (212), comprising: Collecting two or more exhaust gas stream samples (210) from two or more points within an exhaust gas stream (212) downstream of a diesel particulate filter (102); and Guiding the exhaust gas stream samples (210) via a channel (240) to a curvilinear sensor surface (200) such that the exhaust gas stream samples (210) strike the sensor surface (200) at an acute angle (216) with a line (272) that is tangential to a curvature of the curvilinear sensor surface (200), wherein the channel (240) comprises two channel sections (241, 243), wherein a first channel section (241) is oriented substantially orthogonally to a direction of the exhaust gas flow (212), and a second channel section (243) is toroidal, and the second channel section (243) is arranged outside an exhaust gas passage (35) and is arranged substantially coaxially to a central axis of the exhaust gas passage (35) which directs the exhaust gas flow (212) from a diesel engine (10). [10] Method according to claim 9, further comprising positioning interlocking electrodes (202) transverse to an arc which is congruent to the curvilinear sensor surface (200). [11] The method of claim 10, further comprising: Positioning a first pair of oppositely charged interlocking electrodes (202) upstream and longitudinally offset from a second pair of oppositely charged interlocking electrodes (202) with respect to a general flow direction of the guided exhaust gas stream samples (210). [12] Method according to claim 9, wherein the collection of the two or more exhaust gas stream samples (210) includes introducing the exhaust gas stream samples (210) into respective spaced-apart openings (208) along the first channel (241) which is oriented substantially orthogonally to a direction of the exhaust gas stream (212). [13] The method of claim 12, further comprising: Positioning the curvilinear sensor surface (200) within the second channel (243); and Passing of the exhaust gas flow samples (210) from the first channel (241) through the second channel (243). [14] The method of claim 9, wherein the collection of the two or more exhaust gas stream samples (210) comprises introducing the exhaust gas stream samples (210) through openings (208) defined in a frustoconical inner screen (244); and further comprising: Passing of the collected exhaust gas stream samples (210) through a channel (240) defined between the inner screen (244) and an outer screen (246), and impact of the exhaust gas stream samples (210) on the curvilinear sensor surface (200); Discharge of the exhaust gas stream samples (210) through openings (208) defined by the outer screen (246); and Returning the exhaust gas stream samples (210) to the exhaust gas stream (212) minus those soot particles that were captured between the oppositely charged interlocking electrodes (202).

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