METHOD AND SYSTEM FOR CAPTURING FINE PARTICULATES CONTAINED IN EXHAUST GAS

Abstract

Fine dust sensor (106), comprising: a first conductive matrix (300) having a three-dimensional shape defined by dimensions in an X dimension, a Y dimension, and a Z dimension to be charged to a first voltage to act as a positive electrode (400); a second conductive matrix (302) having a three-dimensional shape defined by dimensions in the X dimension, the Y dimension, and the Z dimension, for being charged to a second voltage to act as a negative electrode (402); and that one of the first and second matrices (300, 302) defines first extensions (304) and / or passages (306) and the other of the first and second matrices (300, 302) defines second extensions (304) and / or passages (306), wherein the two extensions (304) and / or passages (306) each traverse and / or closely pass through each other to form a plurality of soot trapping gaps (308) defined by a shortest local distance from the first matrix (300) to the second matrix (302), and wherein a first of the plurality of soot trapping gaps (308) is aligned orthogonally to a second of the plurality of soot trapping gaps (308); and wherein a change in the voltage of the first and / or second matrix (300, 302) occurs due to soot formation in the soot trapping gaps (308) and can be determined as a soot concentration level in an exhaust gas stream from an engine (10).

Description

Area

[0001] This description generally relates to the design and use of particulate matter (PM) resistivity sensors in an exhaust gas stream. General state of the art / brief description

[0002] Diesel combustion can produce emissions, including particulate matter (PM). PM can include diesel soot and aerosols such as ash particles, metallic wear particles, sulfates, and silicates. When PM is released into the atmosphere, it can take the form of individual particles or chain aggregates, most of which are in the invisible submicrometer range of 100 nanometers. Various technologies have been developed to detect and filter out exhaust PM before the exhaust is released into the atmosphere.

[0003] Soot sensors, also known as PM sensors, may be used, for example, in vehicles having internal combustion engines. A PM sensor may be located upstream and / or downstream of a diesel particulate filter (DPF) and may be used to detect PM loading on the filter and diagnose DPF operation. The PM sensor can typically detect particulate matter or soot loading based on a correlation between a measured change in electrical conductivity (or resistance) between a pair of thin electrodes disposed on a planar substrate surface of the sensor and the amount of PM deposited between the sensing electrodes. In particular, the measured conductivity provides a measurement of soot accumulation.

[0004] An exemplary PM sensor is shown by Goulette et al. in US 2015 / 0 153 249 A1. Therein, a conductive material disposed on a substrate is patterned to form interdigitated "comb" electrodes of a PM sensor. When a voltage is applied across the electrodes, soot particles collect on or near the surface of the substrate between the electrodes.

[0005] Other relevant publications are EP 2 325 635 B1 and US 2016 / 0 223 432 A1.

[0006] The inventors of the present invention have recognized potential problems with such systems. In such PM sensors, for example, only a small portion of the PM in the incoming exhaust gases experiences the electrostatic forces exerted between the electrodes and is collected via the electrodes formed on the sensor surface, thus resulting in lower sensor sensitivity. Furthermore, the portion of PM that accumulates on the surface may also be non-uniform due to a bias in the flow distribution across the sensor surface. The PM may tend to collect primarily or exclusively on the inlet side of the sensor, resulting in low and / or non-uniform soot loading. The non-uniform deposition of PM on the sensor surface can further exacerbate the problem of low sensor sensitivity.

[0007] The inventors have recognized the above-mentioned problems and have determined an approach to at least partially solve the problems. In one example, the above-mentioned problems can be solved by a particulate matter sensor comprising: a first conductive matrix having a three-dimensional shape defined by substantial dimensions in an X dimension, a Y dimension, and a Z dimension, for being charged to a first voltage to function as a positive electrode; and a second conductive matrix having a three-dimensional shape defined by substantial dimensions in the X dimension, the Y dimension, and the Z dimension, for being charged to a second voltage to function as a negative electrode. One of the first and second matrices can define extensions and / or passages, and the other of the first and second matrices can define extensions and / or passages.The extensions and / or the passages may each pass through and / or near each other to form a plurality of soot trapping gaps defined by a shortest local distance from the first matrix to the second matrix. A first of the plurality of soot trapping gaps may be oriented orthogonally to a second of the plurality of soot trapping gaps. A change in the voltage of the first and / or second matrix may occur due to soot formation in the soot trapping bridges and may be detected as a soot concentration level in an exhaust stream from an engine. In this way, soot trapping may be better distributed and more uniform, and the sensitivity and reliability of the sensor may be improved.

[0008] For example, a PM exhaust sensor assembly may be disposed downstream of an exhaust particulate filter in an exhaust passage. The PM sensor assembly may be a box-type sensor and may include sealed bottom, top, and side surfaces, and may further include open front and rear surfaces to direct exhaust gas into and out of the assembly.

[0009] Overall, these properties of the sensor array can make an output of the sensor array more accurate, thereby increasing the accuracy of estimating a particle load on a particulate filter.

[0010] It should be understood that the above Summary is provided to introduce, in a simplified form, a selection of concepts that are further elaborated upon in the Detailed Description. It is not intended to identify key features or essential features of the claimed subject matter, the scope of which is defined solely by the claims that follow the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that resolve any of the disadvantages noted above or described in any part of the present disclosure. Brief description of the drawings Fig. Figure 1 shows a schematic diagram of an engine and an associated particulate matter (PM) sensor arranged in an exhaust stream. Fig. Figure 2A is a schematic partial perspective view of the PM sensor illustrating electrically conductive elements in the form of a downstream group of intermeshing comb-like teeth. Fig. 2B is a more complete schematic perspective view of the Fig. 2A shown PM sensor. Fig. 2C is a front view of the Fig. 2B shown sensor. Fig. 2D is a front view of the Fig. 2A shown sensor. Fig. 3A is a schematic view of another embodiment of a PM sensor according to the present disclosure. Fig. 3B is a schematic view of an exemplary portion of a PM sensor according to the present disclosure. Fig. 4 is a perspective view illustrating a portion of another exemplary matrix of electrically conductive material included in a PM sensor according to the present disclosure. Detailed description

[0011] The following description relates to embodiments of a particulate matter sensor, systems, and methods for detecting particulate matter (PM) in an exhaust stream of an engine system, such as the one in Fig. 1. Embodiments may include a controller 12 that may be configured to execute one or more control routines, assist in, or execute various engine operations, which may include one or more routines for collecting exhaust PM via electrodes formed in accordance with the present disclosure. Efficient and well-distributed collection of PM by the embodiments disclosed herein may cause an output of the PM sensor to be more accurate, thereby increasing the accuracy of estimating a particulate load on a particulate filter. Additionally, by enabling more accurate diagnosis of the particulate filter, exhaust emission compliance may be improved. Thus, warranty costs associated with replacing functional particulate filters may be reduced. Additionally, exhaust emission levels may be improved and the lifespan of exhaust components may be extended.

[0012] Fig. 1 shows a schematic representation of a vehicle system 6. The vehicle system 6 includes an engine system 8. The engine system 8 may include an engine 10 having a plurality of cylinders 30. The engine 10 includes an engine intake 23 and an engine outlet 25. The engine intake 23 includes a throttle 62 fluidly coupled to the engine intake manifold 44 via an intake passage 42. The engine outlet 25 includes an exhaust manifold 48 that ultimately leads to an exhaust passage 35 that directs exhaust gas to the atmosphere. The throttle 62 may be disposed in an intake passage 42 downstream of a boosting device, such as a turbocharger (not shown), and upstream of an aftercooler (not shown). If included, the aftercooler may be configured to lower the temperature of intake air compressed by the boosting device.

[0013] The engine exhaust 25 may include one or more emission control devices 70, which may be mounted in a near-engine position within the exhaust. One or more emission control devices may include a three-way catalyst, a lean-burn NOx trap, an SCR catalyst, etc. The engine exhaust 25 may also include a diesel particulate filter (DPF) 102, which temporarily filters PM from incoming gases, located upstream of an emission control device 70. In one example, as illustrated, a DPF 102 is a diesel particulate trap system. A DPF 102 may include a monolithic structure, made from, for example, cordierite or silicon carbide, with a plurality of channels inside for filtering particulate matter from the diesel exhaust.Exhaust gas exiting the tailpipe, which has been filtered of PMs after passing through the DPF 102, may be measured in a particulate matter (PM) sensor 106 and may be further processed in the emissions control device 70 and expelled into the atmosphere via an exhaust passage 35. In the illustrated example, a PM sensor 106 may be a resistive sensor that may be configured to estimate the filtering performance of the DPF 102 based on a change in conductivity measured across the electrodes of the PM sensor 106.

[0014] The vehicle system 6 may further include a control system 14. The control system 14 is illustrated receiving information from a plurality of sensors 16 and sending control signals to a plurality of actuators 81. As an example, sensors 16 may include an exhaust flow rate sensor 126 configured to measure an exhaust flow rate through the exhaust passage 35, an exhaust gas sensor (located in the exhaust manifold 48), a temperature sensor 128, a pressure sensor 129 (located downstream of the emissions control device 70), and a PM sensor 106. Other sensors, such as additional pressure, temperature, air / fuel ratio, exhaust flow rate, and composition sensors, may be coupled to various locations in the vehicle system 6.As another example, the actuators may include fuel injectors 66, a throttle 62, DPF valves that control filter regeneration (not shown), an engine actuator for controlling PM sensor opening (e.g., controlling opening of a valve or plate in an inlet of the PM sensor), etc. As another example, the actuators may include switches coupled to the PM measurement circuitry. The control system 14 may include a controller 12. The controller 12 may be configured with computer-readable instructions stored on non-transitory memory. The controller 12 may receive signals from the various sensors, process the signals, and use various actuators to adjust engine operation based on the received signals and commands stored in a memory of the controller 12.For example, while the PM sensor 106 is operating to collect soot particles, the controller 12 may send one or more control signals to an electrical circuit to apply a voltage to electrodes of a sensor element of a PM sensor assembly 106 to trap the charged particles on the surface of the sensor electrodes of a sensor element. As another example, during a regeneration of the PM sensor 106, the controller 12 may send a control signal to a regeneration circuit to close a switch in the regeneration circuit during a threshold time to apply a voltage to a heating element (not shown) coupled to electrodes to heat the electrodes of the sensor element. In this way, the electrodes are heated to combust soot particles deposited on the surface of the electrodes.

[0015] If you now turn Fig. 2A-2D, schematic views of portions of one embodiment of a particulate matter (PM) sensor 106 are shown. Fig. In particular, Figure 2A is a schematic partial perspective view of the PM sensor 106 illustrating electrically conductive elements in the form of a downstream array 200 of intermeshing comb-like teeth or prongs 202 illustrated in an exemplary box-like structure 204 with sidewalls 206. The intermeshing comb-like teeth or prongs 202 may be a matrix 203 of electrically conductive material or a portion thereof. Fig. 2D is a front view of the Fig. 2A shown sensor 106.

[0016] Fig. 2B is a more complete schematic perspective view of the Fig. 2A shown PM sensor 106 and Fig. 2C is a front view of it. Fig. 2B and Fig. 2C also include a plurality of electrically conductive elements in the form of an upstream group 210 of intermeshing comb-like teeth or prongs 202 in the exemplary box-like structure 204. Arrows illustrate a flow direction 212 of the exhaust gas flow.

[0017] Fig. 3A-3B are schematic views of another embodiment of a particulate matter (PM) sensor 106 according to the present disclosure. Another example of an electrically conductive material matrix 203 according to the present disclosure is also illustrated. Electrically conductive elements may take the form of a plurality of interposed or interwoven elongated elements 214. Fig. Figure 3A illustrates interwoven elongate elements 214 disposed on or coupled to a substrate 216 or other support mechanisms. Fig. 3B illustrates an example of interwoven elongate elements 214 according to the present disclosure, which may be connected to the same or a similar substrate or which may be a portion of a larger matrix of electrodes, which may, for example, be repeated incrementally any number of times to form a larger matrix 203 of electrically conductive material.

[0018] Fig. 4 is a perspective view illustrating a portion of another exemplary matrix 203 of electrically conductive material. A first electrically conductive element 220 may define one or more through-holes 222. A second electrically conductive element 224 may be arranged to pass into or through the hole(s) 222. As shown in Fig. As shown in Figure 4, the elements are planar, flat, and have a substantially constant thickness. The end 305 that passes through the hole 222 does so without contacting the inner walls of the hole.

[0019] Looking again Fig. 2A-2D and Fig. 3A-3B, in particular Fig. 2B and 3A-3B, embodiments may include a particulate matter sensor 106 including a first conductive matrix 300. A first conductive matrix 300 may have a three-dimensional shape defined by substantial dimensions in an X dimension, a Y dimension, and a Z dimension to be charged to a first voltage to function as a positive electrode. Embodiments may also include a second conductive matrix 302 having a three-dimensional shape defined by substantial dimensions in the X dimension, the Y dimension, and the Z dimension to be charged to a second voltage to function as a negative electrode. The first conductive matrix 300 may include a portion of the upstream matrix 210 discussed above and a portion of the downstream matrix 200.Likewise, the second conductive matrix 302 may include a portion of the upstream matrix 210 discussed above and a portion of the downstream matrix 200. It will be understood that the first matrix 300 may be maintained at a different electrical potential than the second matrix 302. Each of the matrices 300, 302 may be formed in different geometries.

[0020] For example, non-negligible dimensions may be defined as dimensions that are within an order of magnitude of a dimension of reasonably distinguishable features of the disclosed matrices, such as a change in direction or a distinguishable width or length. A non-negligible dimension may, for example, be a dimension across a body element that is greater than the thickness of the body element.

[0021] Soot, or PM, in the exhaust gas is typically charged. Due to electrostatic attraction between the charged PM and the interdigitated electrodes, PM deposits on the electrodes and forms bridges across the interdigitated electrodes.

[0022] One of the first and second dies 300, 302 may define extensions 304 and / or passages 306. The other of the first and second dies 300, 302 may also or instead define extensions 304 and / or passages 306. The extensions 304 and / or passages 306 may each traverse and / or pass near each other to form a plurality of soot trapping gaps 308. One extension 304 may be configured to form one passage 306. Fig. For example, Figure 3B illustrates extensions 304 changing direction to define a shape, allowing another extension 304 to pass through, thereby forming a passage 306.

[0023] For example, individual soot trapping gaps 308 can be defined as a shortest local distance from the first matrix 300 to the second matrix 302. One or more gaps can also be considered to be formed from prongs 202, i.e., extensions 304 that are close to each other but spaced apart. As in Fig. 2B, a first gap 310 of the plurality of soot trapping gaps 308, shown with a first dimension, may be oriented orthogonally to a second gap 312 of the plurality of soot trapping gaps 308, shown with a second dimension. A change in the voltage of the first matrix 300 and / or second matrix 302 may occur due to soot formation in the soot trapping bridges 308 and may be determined as a soot concentration level in an exhaust stream from an engine 8 ( Fig. 1).

[0024] In various embodiments, the orientation of the first soot trapping gap 310 may be substantially transverse to the flow direction 212 of the exhaust gas flow, and the orientation of the second soot trapping gap 312 may be substantially parallel to the general flow direction 212 of the exhaust gas flow. The extensions 304 of the first conductive matrix 300 may include a first group of electrically conductive comb-like prongs 202, and the extensions 304 of the second conductive matrix 302 may include a second group of electrically conductive comb-like prongs 202 that engage the first group of electrically conductive comb-like prongs 202.

[0025] The first group of interlocking comb-like prongs 202 may be selected in alternating order from the first matrix 300 and the second matrix 302 and arranged substantially orthogonal to a general flow direction 212 of the exhaust stream. A second group of interlocking comb-like prongs 202 may be selected in alternating order from the second matrix 302 and the first matrix 300 and arranged substantially parallel to the first group of interlocking comb-like prongs 202.

[0026] The first soot trapping gap 310 may be oriented substantially transverse to the general flow direction 212 from the first matrix 300 to the second matrix 302 within the first group of interlocking comb-like tines, i.e., the upstream group 210 of interlocking tines 202. The second soot trapping gap 312 may be oriented substantially according to the general flow direction 212 from the first matrix 300 to the second matrix 302 and from the first group of interlocking comb-like tines to the second group of interlocking comb-like tines 202, i.e., from the upstream group 210 of interlocking tines 202 to the downstream group 200 of interlocking tines 202.

[0027] Reference is again made to Fig. 4, various embodiments of the particulate matter sensor 106 may include one or more passages from the first conductive matrix 300, which may include one or more holes 222. One or more extensions 304 from the second conductive matrix 302 may extend into the one or more holes 222. The one or more extensions 304 may extend toward the hole in a direction substantially axial to the hole 222 or in an angular direction. The extension 304 may extend through the hole 222, or an end 305 of the extension may be at a height of the hole 222, i.e., corresponding to the material of the second electrical contact pair. In some cases, the end 305 of the extension 304 may be spaced a distance from the hole 222 without traversing the hole 222.

[0028] Reference is again made to Fig. 3A-3B, extensions 304 from a first conductive matrix 300 and extensions 304 from a second conductive matrix 302 may each define serrated profiles. The respective serrated profiles may be interposed and / or interwoven to form the plurality of soot trapping gaps 308 or bridges. The plurality of soot trapping gaps 308 may be oriented in a plurality of different directions. For example, a first gap 310 may be oriented in a first direction, such as orthogonal to a flow direction 212 of the exhaust stream. A second gap 312 may be oriented orthogonal to the first gap 310. A third gap 314 may be orthogonal to both the first gap 310 and the second gap 312. Additional gap directions may be used.

[0029] Various embodiments may provide a particulate matter (PM) sensor 106 for use in an engine exhaust. The PM sensor 106 may include a positive electrode 400 having a plurality of extensions and / or a plurality of passages, and a negative electrode 402 having a plurality of conductor extensions 304 and / or a plurality of passages. The extensions 304 and the passages 306 may each traverse and / or pass near each other to form a plurality of soot trapping gaps 308 between the positive electrode 400 and the negative electrode 402. Each soot trapping gap 308 may have an orientation defined by a shortest local distance between the positive electrode 400 and the negative electrode 402, where a first portion of the soot trapping gap 308 may be oriented substantially orthogonal to a second portion of soot trapping gaps 308.

[0030] The positive electrode 300 may be electrically coupled to a positive main electrode 316 ( Fig. 3A). The positive main electrode 316 may be attached to a substrate 216. The negative electrode 302 may be electrically connected to a negative main electrode 318, which may also be connected to or attached to the substrate 216. The positive electrode 300 and the negative electrode 302 may be located in a box-like housing, a tubular housing, or a housing of another shape.

[0031] In some cases, each gap 310 may be oriented from the first portion of the soot trapping gap 308 substantially transverse to a flow direction 212 of the engine exhaust. Additionally or alternatively, each gap 312 may be oriented from the second portion of the soot trapping gap 308 substantially corresponding to the engine exhaust. The positive electrode 400 may include a first set of extensions 304, and the negative electrode may include a second set of extensions 304 that engage the first set of extensions 304.

[0032] Embodiments may provide a PM sensor 106 wherein extensions from the positive electrode 400 and extensions from the negative electrode 402 may each define serrated profiles. The respective serrated profiles may be interposed or interwoven to form the plurality of soot trapping gaps 308. A third portion of the soot trapping gap 314 may be oriented substantially orthogonal to the first portion and the second portion of soot trapping electrodes.

[0033] Embodiments according to the present disclosure may provide various methods. An example method may include orienting a first group of electrical contact pairs in a first direction to accumulate a first group of soot bridges along the first direction. The method may include orienting a second group of electrical contact pairs in a second direction orthogonal to the first direction to accumulate a second group of soot bridges along the second direction. The method may also include transmitting an electrical property to each of the first and second groups of electrical contact pairs and sensing a soot level in a diesel exhaust stream based on measuring a change in the electrical properties after accumulation of soot from the exhaust stream at the first and second groups of soot bridges.A change in electrical properties may be performed by or in conjunction with the controller 12. Measuring a change in electrical properties may include measuring an aggregate change in conductivity between a negative electrode portion of each of the first and second electrical contact pairs and a positive electrode portion of each of the first and second electrical contact pairs.

[0034] Aligning the first and second sets of electrical contact pairs may comprise engaging a first set of electrically conductive comb-like prongs with a second set of comb-like prongs and defining the first and second sets of electrical contact pairs as localized minimum distances between the first and second sets of comb-like prongs. Aligning the first and second sets of electrical contact pairs may comprise extending an extension member as the first of the electrical contact pairs through or adjacent to a hole defined in a second of the electrical contact pairs. The extension member may, for example, extend in a substantially axial direction to the hole, but the end may, for example, extend to a plane of the hole, i.e., to a plane of the material of the second electrical contact pair.

[0035] Various embodiments may include a method that includes aligning a third group of electrical contact pairs in a third direction to accumulate a third group of soot bridges along the third direction orthogonal to each of the first direction and the second direction. Sensing may include measuring the change in electrical property to include the third group of soot bridges. Aligning a third group of electrical contact pairs may include interweaving a first group of toothed, electrically conductive extensions with a second group of toothed, electrically conductive extensions and defining the first, second, and third groups of electrical contact pairs as localized minimum distances between the first and second groups of toothed, electrically conductive extensions.Various methods may include electrically connecting a first portion of each of the electrical contact pairs to a positive main electrode and electrically connecting a second portion of each of the electrical contact pairs to a negative main electrode.

[0036] The PM sensor 106 may be configured to measure a PM mass and / or concentration in the exhaust gas and, as such, may be connected to an exhaust passage (e.g., the one shown in Fig. 1) upstream or downstream of a diesel particulate filter (such as the one shown in Fig. 1 shown DPF 102).

[0037] The PM sensor 106 with electrodes may be disposed within a protective tube (not shown) and may include conduits (not shown) within the tube that can conduct the exhaust gases to the electrodes. The electrodes may be made of metals such as platinum, gold, osmium, rhodium, iridium, ruthenium, aluminum, titanium, zirconium, and the like, as well as oxides, cement, alloys, and combinations comprising at least one of the foregoing metals. The electrodes may be formed on a substrate of the PM sensor 106, which may be made of highly electrically insulating materials.

[0038] Possible electrically insulating materials may include oxides such as alumina, zirconia, yttria, lanthanum oxide, silicon dioxide, and combinations comprising at least one of the foregoing, or any similar material that can prevent electrical communication and provide physical protection for the pair of interdigitated electrodes.

[0039] The substrate of the PM sensor 106 may include a heating element (not shown), and the PM sensor may be regenerated by heating the sensor substrate via the heating element to burn off the accumulated soot particles from the surface of the PM sensor 106. By intermittently regenerating the surface of the PM sensor 106, it may return to a state more conducive to the accumulation of exhaust soot. Furthermore, accurate information about the exhaust soot level may be derived from the sensor regeneration and relayed to the controller.

[0040] Furthermore, the voltage source and the measuring device and the electrical circuit can be controlled by a controller, such as the controller 12 Fig. 1, so that particulate matter collecting at the PM sensor can be used, for example, to diagnose leaks in the DPF. Thus, the measuring device can be any device that can read a change in resistance across the electrodes, such as a voltmeter. As PM or soot particles become deposited between the electrodes, the resistance between the electrode pair may decrease, which may be indicated by a decrease in the voltage measured by the measuring device. The controller 12 can determine the resistance between the electrodes as a function of a voltage measured by the measuring device 218 and derive a corresponding PM or soot loading on the electrodes of the PM sensor 106 therefrom.By monitoring the loading on the PM sensor 106, the exhaust soot loading downstream of the DPF can be determined and thus used to diagnose and monitor the condition and functionality of the DPF. In some examples, the controller 12 can adjust the voltage source to supply a specific voltage to the electrodes of the PM sensors. If switches are arranged in the electrical circuit, the controller 12 can determine the closing and opening of the switches based on a condition of the PM sensor. For example, if the PM sensor is accumulating PM, the switches in the electrical circuit can be adjusted to apply voltages to the sensor's electrodes. However, if the PM sensor is regenerating, the switches connecting the electrodes to the voltage source can be opened. Further, the heater circuit can be activated by the controller.

[0041] In this way, a more accurate measurement of exhaust PM loading and thus DPF soot loading can be determined. This therefore improves the efficiency of filter regeneration processes and reduces the need for extensive algorithms. Furthermore, by enabling more accurate diagnosis of an exhaust DPF, compliance with exhaust emission standards can be improved. This thus reduces the high warranty costs for replacing functional particulate filters, and exhaust emissions are improved and the service life of the exhaust component is extended.

[0042] Instructions for performing methods according to the present disclosure may be executed by the controller 12 and may be based on instructions stored in a memory of the controller 12 and may be associated with signals received from sensors of the engine system, such as those described above with reference to Fig. 1. The controller 12 may use motor actuators of the engine system to adjust engine operation according to the methods described below.

[0043] Systems and methods according to the present disclosure may include determining and / or estimating engine operating conditions, including exhaust flow conditions. Determined engine operating conditions may include, for example, engine speed, exhaust flow direction, exhaust flow rate, engine temperature, exhaust air-fuel ratio, exhaust temperature, elapsed time (or distance) since a last DPF regeneration, PM loading on the PM sensor, boost level, ambient conditions such as barometric pressure and ambient temperature, etc. Exhaust flow conditions include estimating or sensing one or more of the soot loading of the PM sensor array, exhaust flow rate, exhaust flow direction, exhaust temperature, and the like.

[0044] Embodiments may include a heating element coupled to the controller 12. The controller may include or utilize computer-readable instructions that may be stored in non-volatile memory. During an exhaust flow, the controller 12 may implement instructions to apply a first voltage to the positive electrode and a second voltage to the negative electrode to accumulate exhaust particulate matter in the exhaust flow via the gap 308. The controller 12 may receive signals from the PM sensor 106 to estimate a soot loading on the particulate matter sensor assembly based on a current generated across the positive and negative electrodes. In some cases, in response to a soot loading greater than a threshold, a voltage may be applied to the heating element of the sensor assembly to regenerate the sensor assembly.

[0045] Fig.2-4 show example configurations with relative positioning of the various components. When such elements are depicted in direct contact with one another or in direct connection, they may be referred to as being in direct contact or in direct connection, at least in one example. Likewise, elements depicted as being adjacent or adjacent to one another may be adjacent or adjacent to one another, at least in one example. Components that are in face-to-face contact with one another, for example, may be referred to as being in face-to-face contact. As another example, elements that are spaced apart from one another with only a space between them and no other components may be referred to as such, in at least one example.As another example, elements depicted above or below each other, on opposite sides of each other, or to the left / right of each other may be referred to as such relative to each other. Further, as depicted in the figures, in at least one example, a topmost element or element point may be referred to as a "top" of the components, and a bottommost element or element point may be referred to as a "bottom" of the component. As used herein, top / bottom, upper / lower, above / below may be located relative to a vertical axis of the figures and may be used to describe the arrangement of elements of the figures relative to one another. As such, elements depicted above other elements are, in one example, arranged vertically above the other elements.As another example, shapes of elements depicted within the figures may be referred to as having these shapes (e.g., circular, straight, planar, curved, rounded, beveled, angled, or the like). Further, elements depicted as intersecting may, in at least one example, be referred to as intersecting elements or intersecting. Still further, an element depicted as being inside another element or depicted as being outside another element may, in one example, be referred to as such.

[0046] In another representation, an example method includes generating a first electric field in a first direction to accumulate a first group of soot bridges along the first direction; generating a second, orthogonal electric field in a second direction to accumulate a second group of soot bridges along the second direction, the first direction being orthogonal to the second direction; and detecting a soot loading of a sensor based on each of the first group of soot bridges and the second group of soot bridges.The exemplary method may include one or more or each of generating a third electric field to accumulate a third group of soot bridges along a third direction, the third direction being orthogonal to each of the first direction and the second direction, and adjusting the sensed soot loading based on the third group of soot bridges accumulated along the third direction, wherein each of the first electric field, the second electric field, and the third electric field is generated between positive and negative electrodes forming a plurality of crossover patterns on a surface of the assembly.

[0047] In another illustration, an exemplary particulate matter sensor includes positive electrodes extending orthogonally to a first substrate; negative electrodes extending orthogonally to a second substrate and interdigitated with the positive electrodes, wherein the second substrate faces the first substrate and is separated from the first substrate by a gap.In another example, the particulate matter (PM) sensor comprises a first substrate extending in a first direction, having a group of electrodes protruding from a surface of the first substrate in a second direction, the second direction being orthogonal to the first direction; and a second substrate spaced from the first substrate and extending along the first direction, the second substrate having a second group of electrodes protruding from a surface of the second substrate in a third direction, the third direction being opposite to the second direction, optionally wherein the first, second, and third directions are orthogonal to a direction of exhaust gas flow, the first group of electrodes and the second group of electrodes being interdigitated.

[0048] It should be noted that the exemplary control and estimation routines included herein may be used with various engine and / or vehicle system configurations. Selected effects of the control methods and routines disclosed herein may be stored as executable instructions in non-volatile memory and may be performed by the control system, including the controller in combination with the various sensors, actuators, and other engine hardware. The particular routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, various illustrated acts, operations, and / or functions may be performed in the order illustrated, executed in parallel, or in some cases omitted.Likewise, the order of processing is not necessarily required to achieve the features and advantages of the embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, procedures, and / or functions may be performed repeatedly depending on the particular strategy employed. Further, the described acts, procedures, and / or functions may graphically represent code to be programmed into non-transitory memory of the computer-readable storage medium in the engine control system, where the described acts are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.

[0049] It is understood that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, as numerous variations are possible. For example, the above technology may be applied to V-6, I-4, I-6, V-12, Opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or characteristics disclosed herein.

[0050] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "an" element or "a first" element, or the equivalent thereof. Such claims should be understood to encompass the inclusion of one or more such elements, neither requiring nor 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.

[0051] Such claims, whether broader, narrower, or different in scope from the original claims, are also deemed to be included within the subject matter of the present disclosure.

Claims

[1] Fine dust sensor (106), comprising: a first conductive matrix (300) having a three-dimensional shape defined by dimensions in an X dimension, a Y dimension, and a Z dimension to be charged to a first voltage to act as a positive electrode (400); a second conductive matrix (302) having a three-dimensional shape defined by dimensions in the X dimension, the Y dimension, and the Z dimension, for being charged to a second voltage to act as a negative electrode (402); and that one of the first and second matrices (300, 302) defines first extensions (304) and / or passages (306) and the other of the first and second matrices (300, 302) defines second extensions (304) and / or passages (306), wherein the two extensions (304) and / or passages (306) each traverse and / or closely pass through each other to form a plurality of soot trapping gaps (308) defined by a shortest local distance from the first matrix (300) to the second matrix (302), and wherein a first of the plurality of soot trapping gaps (308) is aligned orthogonally to a second of the plurality of soot trapping gaps (308); and wherein a change in the voltage of the first and / or second matrix (300, 302) occurs due to soot formation in the soot trapping gaps (308) and can be determined as a soot concentration level in an exhaust gas stream from an engine (10). [2] Particulate matter sensor (106) according to claim 1, wherein the orientation of the first soot trapping gap (308) is transverse to a flow direction of the exhaust gas flow (212) and the orientation of the second soot trapping gap (308) is parallel to the exhaust gas flow. [3] The particulate matter sensor (106) of claim 1, wherein the extensions (304) of the first conductive matrix (300) comprise a first group of electrically conductive comb-like prongs (202) and the extensions (304) of the second conductive matrix (302) comprise a second group of electrically conductive comb-like prongs (202) that engage the first group of electrically conductive comb-like prongs (202). [4] Fine dust sensor (106) according to claim 3, wherein: a first group of interlocking comb-like prongs (202) is selected in alternating order from the first matrix (300) and the second matrix (302) and is arranged substantially orthogonal to the flow direction of the exhaust gas stream (212), and a second group of interlocking comb-like prongs (202) is selected in alternating order from the second matrix (302) and the first matrix (300) and is arranged substantially parallel to the first group of interlocking comb-like prongs (202); and the first soot trapping gap (308) is oriented substantially transversely to the flow direction of the exhaust gas stream (212) from the first matrix (300) to the second matrix (302) within the first group of intermeshing comb-like prongs (202) and the second soot trapping gap (308) is aligned substantially in accordance with the flow direction of the exhaust gas flow (212) from the first matrix (300) to the second matrix (302) and from the first group of interlocking comb-like prongs (202) to the second group of interlocking comb-like prongs (202) and forms respective bridges of alternating polarity in a first direction substantially transverse to the flow direction of the exhaust gas stream (212) and in a second direction substantially parallel to the flow direction of the exhaust gas stream (212). [5] The particulate matter sensor (106) of claim 1, wherein a passage (306) from the second conductive matrix (302) comprises a hole (222) and wherein an extension (304) extends from the first conductive matrix (300) into the hole (222). [6] The particulate matter sensor (106) of claim 1, wherein extensions (304) of the first conductive matrix (300) and extensions (304) of the second conductive matrix (302) each define toothed profiles, and wherein the respective toothed profiles are interwoven to form the plurality of soot trapping gaps (308). [7] Method comprising: Aligning a first group of electrical contact pairs in a first direction to accumulate a first group of soot bridges along the first direction; Aligning a second group of electrical contact pairs in a second direction orthogonal to the first direction to accumulate a second group of soot bridges along the second direction; Detecting a soot level in diesel exhaust gases based on electrical properties of the first and second groups of electrical contact pairs and Transferring an electrical property to each of the first and second groups of electrical contact pairs, wherein detecting a soot level in diesel exhaust based on electrical properties comprises measuring a change in the electrical properties, and measuring a change in the electrical properties comprises measuring an aggregate change in conductivity between a negative electrode portion of each of the first and second groups of electrical contact pairs and a positive electrode portion of each of the first and second groups of electrical contact pairs. [8] The method of claim 7, wherein aligning the first and second groups of electrical contact pairs comprises intermeshing a first group of electrically conductive comb-like prongs (202) with a second group of comb-like prongs (202) and defining the first and second groups of electrical contact pairs as localized minimum distances between the first and second groups of comb-like prongs (202). [9] The method of claim 7, wherein aligning a first and second group of electrical contact pairs comprises extending an extension member (304) as a first of the electrical contact pairs through or adjacent a hole (222) defined in a second of the electrical contact pairs. [10] The method of claim 7, further comprising aligning a third group of electrical contact pairs in a third direction to accumulate a third group of soot bridges along the third direction orthogonal to each of the first direction and the second direction, and wherein the sensing comprises measuring a change in the electrical property of the first, second, and third groups of soot bridges. [11] The method of the preceding claim, wherein aligning a first and second group of electrical contact pairs comprises interweaving a first group of toothed, electrically conductive extensions (304) with a second group of toothed, electrically conductive extensions (304) and defining the first, second and third groups of electrical contact pairs as localized minimum distances between the first and second groups of toothed, electrically conductive extensions (304). [12] The method of claim 7, further comprising electrically connecting a first portion of each of the electrical contact pairs to a positive main electrode (316) and electrically connecting a second portion of each of the electrical contact pairs to a negative main electrode (318).

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