US20140290217A1 - Method and system pertaining to monitoring particle emissions in combustion engine exhausts - Google Patents

Method and system pertaining to monitoring particle emissions in combustion engine exhausts Download PDF

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US20140290217A1
US20140290217A1 US14/357,826 US201214357826A US2014290217A1 US 20140290217 A1 US20140290217 A1 US 20140290217A1 US 201214357826 A US201214357826 A US 201214357826A US 2014290217 A1 US2014290217 A1 US 2014290217A1
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Prior art keywords
particle
exhaust flow
sensor
particle content
engine
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US14/357,826
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English (en)
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Ola Stenlåå
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Scania CV AB
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Scania CV AB
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Publication of US20140290217A1 publication Critical patent/US20140290217A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/04—Filtering activity of particulate filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/05—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a particulate sensor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to exhaust cleaning and in particular to a method for determining a particle content in an exhaust flow according to the preamble of claim 1 .
  • the invention relates also to a system and a vehicle, and to a computer programme and a computer programme product, which implement the method according to the invention.
  • Such emission standards often set requirements which define acceptable limits for exhaust emissions from vehicles equipped with combustion engines. These standards often regulate, for example, levels for emissions of nitrogen oxides (NO x ), hydrocarbons (HC) and carbon monoxide (CO). These emission requirements also usually cover, for at least certain kinds of vehicle, the presence of particles in exhaust emissions.
  • NO x nitrogen oxides
  • HC hydrocarbons
  • CO carbon monoxide
  • post-treatment systems often comprise some form of catalytic cleaning process whereby one or more catalysts are used to clean the exhaust gases.
  • Such post-treatment systems often comprise other components as alternatives to, or in combination with, the one or more catalysts, e.g. post-treatment systems on vehicles with diesel engines often comprise particle filters.
  • Soot particles are formed during combustion of fuel in the combustion chambers (e.g. cylinders) of a combustion engine. As above, these soot particles are likewise subject to emission requirements and standards, which may entail using particle filters to intercept the soot particles. In such cases the exhaust flow is for example led through a filter structure whereby soot particles are captured from the passing exhaust flow in order to be stored in the particle filter.
  • Post-treatment systems with particle filters can be very effective and the resulting particle content after the exhaust flow has passed through the vehicle's post-treatment system is often low when the system is fully functional. This also means that the signals which the sensor delivers will indicate low or no particle emission.
  • An object of the invention is to propose a method for diagnosis of a combustion engine pertaining to a vehicle. This object is achieved with a method according to claim 1 .
  • the present invention proposes a method for diagnosis of a combustion engine whereby a post-treatment system comprising at least one particle filter is provided to post-treat an exhaust flow arising from combustion in said engine.
  • the method comprises
  • a particle content at a location upstream of said particle filter and then using this particle content as a basis for determining whether the particle content downstream of the filter fulfils a first condition e.g. being less than a second particle content
  • a first condition e.g. being less than a second particle content
  • these requirements may for example take the form of a maximum permissible particle content defined for example as particle mass per unit engine power output, e.g. a certain particle mass per kW of developed or deliverable power output, and said condition may also take the form of the particle content released having to meet the requirements.
  • Said second particle content may for example be set at a level which just meets the requirements or meets them with a desired margin.
  • the condition e.g. the second particle content, may also be set at a higher level than the requirements.
  • the invention affords the further advantage that problems in ensuring the reliability of the sensor in sensor solutions of the kind described above can be reduced and that an improved method for determining particle emissions from combustion in a combustion engine can be achieved.
  • the engine may itself meet prevailing requirements in that the particle content in said exhaust flow downstream of said particle filter may be arranged to fulfil said first condition if said first particle content determined fulfils said first condition.
  • the particle filter of said exhaust flow downstream of said particle filter may be such as to fulfil said first condition if said first particle content determined conforms to a specific ratio to said maximum permissible particle emission, e.g. by being not more than said maximum permissible particle emission multiplied by some appropriate factor.
  • said first condition depends on a differential pressure across the particle filter, e.g. in that a condition in the form of a particle content may depend on the differential pressure so that the maximum level which said first particle content may reach can be arranged to decrease in step with increasing differential pressure.
  • the present invention affords also the advantage that the PM sensor, owing to the higher particle content of the exhaust flow upstream of the particle filter, will more frequently or more or less regularly deliver a signal which indicates that there is soot in the exhaust flow.
  • the signal will thus also be significantly more reliable and therefore also easier to diagnose.
  • Locating the PM sensor upstream affords the further advantage that it can with greater certainty be so located as to have passing it a well-mixed and homogeneous exhaust flow without substantial distribution problems, potentially also providing assurance of measured values which are more correct.
  • the present invention makes it possible to monitor that requirements with regard to particle emission after the particle filter are met without having to conduct actual measurement of the particle content after the particle filter, even in the case of engines whose particle content in the exhaust flow upstream of the filter does not meet prevailing requirements.
  • FIG. 1 a depicts schematically a vehicle on which the present invention may be employed.
  • FIG. 1 b depicts a control unit in the control system for the vehicle depicted in FIG. 1 .
  • FIG. 2 depicts the post-treatment system in more detail for the vehicle depicted in FIG. 1 .
  • FIG. 3 depicts an example of a method according to the present invention.
  • particle content in the description and claims set out below comprises both content in the form of unit weight and content/concentration, i.e. the unit number of particles.
  • the unit may be any suitable unit and the content may be expressed as, for example, weight or number of particles per unit volume, per unit time, per work performed or per distance travelled by the vehicle.
  • FIG. 1 a depicts a power train of a vehicle 100 according to an embodiment of the present invention.
  • the vehicle schematically depicted in FIG. 1 has only one axle provided with tractive wheels 113 , 114 but the invention is also applicable on vehicles in which more than one axle is provided with tractive wheels.
  • the power train comprises a combustion engine 101 which is connected in a conventional way, via an output shaft of the engine, usually via a flywheel 102 , to a gearbox 103 via a clutch 106 .
  • the engine is controlled by the vehicle's control system via a control unit 115 .
  • the clutch 106 which may for example take the form of an automatically controlled clutch, and the gearbox 103 are also controlled by the vehicle's control system by means of one or more suitable control units (not depicted).
  • the vehicle's power train may of course also be of some other kind, e.g. a type with conventional automatic gearbox etc.
  • An output shaft 107 from the gearbox 103 then drives the tractive wheels 113 , 114 via a final gear 108 , e.g. a conventional differential, and driveshafts 104 , 105 which are connected to said final gear 108 .
  • a final gear 108 e.g. a conventional differential, and driveshafts 104 , 105 which are connected to said final gear 108 .
  • the vehicle 100 further comprises a post-treatment system (exhaust cleaning system) 200 for treatment (cleaning) of exhaust emissions arising from combustion in the engine's combustion chambers (e.g. cylinders).
  • a post-treatment system exhaust cleaning system 200 for treatment (cleaning) of exhaust emissions arising from combustion in the engine's combustion chambers (e.g. cylinders).
  • the post-treatment system is depicted in more detail in FIG. 2 , showing the vehicle's engine 101 from which the exhaust gases (the exhaust flow) generated by the combustion are led through a turbo unit 220 .
  • the exhaust flow arising from the combustion often drives a turbo unit which itself compresses the incoming air for the combustion in the cylinders.
  • the turbo unit may for example be of compound type.
  • the function of various kinds of turbo unit is well-known and is therefore not described in more detail here.
  • the exhaust flow is then led via a pipe 204 (indicated by arrows) to a particle filter (diesel particulate filter, DPF) 202 via an oxidation catalyst (diesel oxidation catalyst, DOC) 205 .
  • DPF diesel particulate filter
  • DOC oxidation catalyst
  • the oxidation catalyst DOC 205 has various functions and is normally used primarily to oxidise remaining hydrocarbons and carbon monoxide in the exhaust flow to carbon dioxide and water.
  • the oxidation of hydrocarbons i.e. oxidation of fuel
  • the oxidation catalyst may also be used to oxidise nitrogen monoxide (NO) to nitrogen dioxide (NO 2 ) which may be utilised in so-called passive regeneration.
  • Post-treatment systems of the type referred to may also comprise other components, e.g. a (single, in the present example) SCR (selective catalytic reduction) catalyst 201 situated downstream of the particle filter 202 .
  • SCR catalysts use ammonia (NH 3 ), or a compound from which ammonia can be generated/formed, as additive to reduce the amount of nitrogen oxides NO x .
  • the post-treatment system 200 may also comprise more components than as exemplified above or, conversely, fewer components. It may for example comprise an ASC (ammonia slip catalyst) (not depicted) in addition to, or instead of, said DOC 205 and/or SCR 201 .
  • ASC ammonia slip catalyst
  • DOC 205 , DPF 202 and also the SCR catalyst 201 are integrated in a combined exhaust cleaning unit 203 , but it should be noted that DOC 205 and DPF 202 need not be integrated in a single exhaust cleaning unit, as they may be arranged in some other way deemed appropriate.
  • the post-treatment system 200 comprises a PM sensor 222 situated upstream of DPF 202 .
  • This PM sensor like other sensors associated with the post-treatment system, e.g. a pressure sensor 209 , may deliver signals to a control unit 208 , or some other suitable control unit, which controls or monitors the function of the post-treatment system.
  • the determination of appropriate times for regeneration of the particle filter may be done by the control unit 208 at least partly on the basis of signals from the pressure sensor 209 which measures the differential pressure across the filter. The fuller the filter becomes, the greater will be the pressure difference across it.
  • the pressure sensor may for example also be used for diagnosis of DPF 202 but also when determining whether a particle content after the particle filter fulfils a condition according to the present invention, as described below.
  • Control systems in modern vehicles generally comprise a communication bus system consisting of one or more communication buses for connecting together a number of electronic control units (ECUs), e.g. the control units or controllers 115 , 208 , and various components located on the vehicle.
  • ECUs electronice control units
  • Such a control system may comprise a large number of control units and the responsibility for a specific function may be shared by two or more of them.
  • control units 115 , 208 appear in FIG. 1 a.
  • the present invention is implemented in the control unit 208 , which as above is responsible in the embodiment depicted for other functions in the post-treatment system, e.g. regeneration (emptying) of the particle filter 202 , although the invention may equally well be implemented in a control unit dedicated to it, or wholly or partly in one or more other control units with which the vehicle is already provided, e.g. the engine control unit 115 .
  • control unit 208 (or the control unit or units in which the present invention is implemented) will depend not only on signals from the PM sensor 222 but probably also on, for example, information received from, for example, the control unit or units which control engine functions, i.e. in the present example the control unit 115 .
  • Control units of the type depicted are normally adapted to receiving sensor signals from various parts of the vehicle.
  • the control unit 208 may for example receive sensor signals as above and also from the engine control unit 115 and other control units.
  • Such control units are also usually adapted to delivering control signals to various parts and components of the vehicle, e.g. the control unit 208 may for example deliver signals to the engine control unit 115 .
  • control is often governed by programmed instructions, typically in the form of a computer programme which, when executed in a computer or control unit, causes the computer/control unit to effect desired forms of control action, e.g. method steps according to the present invention.
  • the computer programme usually forms part of a computer programme product which comprises a digital storage medium 121 (see FIG. 1 b ) with the computer programme 109 stored on it.
  • Said digital storage medium 121 may for example take the form of any from among ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable PROM), flash memory, EEPROM (electrically erasable PROM), a hard disc unit etc., and be situated in or in communication with the control unit, in which case the computer programme is executed by the control unit.
  • ROM read-only memory
  • PROM programmable read-only memory
  • EPROM erasable PROM
  • flash memory erasable PROM
  • EEPROM electrically erasable PROM
  • a hard disc unit etc. and be situated in or in communication with the control unit, in which case the computer programme is executed by the control unit.
  • the vehicle's behaviour in a specific situation may thus be modified by altering the computer programme's instructions.
  • control unit may itself comprise a calculation unit 120 which may for example take the form of any suitable kind of processor or microcomputer, e.g. a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit with a predetermined specific function (Application Specific Integrated Circuit, ASIC).
  • the calculation unit 120 is connected to a memory unit 121 which provides it with, for example, the stored programme code 109 and/or the stored data which the calculation unit needs for it to be able to perform calculations.
  • the calculation unit is also arranged to store partial or final results of calculations in the memory unit 121 .
  • the control unit is further provided with respective devices 122 , 123 , 124 , 125 for receiving and sending input and output signals. These signals may comprise waveforms, pulses or other attributes which the input signal receiving devices 122 , 125 can detect as information for processing by the calculation unit 120 .
  • the output signal sending devices 123 , 124 are arranged to convert calculation results from the calculation unit 120 to output signals for conveying to other parts of the vehicle's control system and/or the component/components for which the signals are intended.
  • Each of the connections to the respective devices for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g. a CAN (Controller Area Network) bus, an MOST (Media Oriented Systems Transport) bus or some other bus configuration, or a wireless connection.
  • a data bus e.g. a CAN (Controller Area Network) bus, an MOST (Media Oriented Systems Transport) bus or some other bus configuration, or a wireless connection.
  • the combustion in the combustion chambers of the engine 101 results in the formation of particles which should not and in many cases are not permitted to be released into the vehicle's surroundings.
  • the particles formed during combustion in, for example, a diesel engine consist largely of hydrocarbons, carbon (soot) and inorganic substances such as sulphur and ash. Soot particles may for example be formed when the fuel/air ratio during combustion in the engine's combustion chambers becomes too great, i.e. when there is a so-called “rich” fuel mixture with too high a proportion of fuel relative to that of air.
  • the fuel/air ratio for a specific combustion i.e. the amounts of air and fuel injected during a specific piston stroke, may be such that the requirement for non-sooting combustion is met, the fuel/air ratio may still occur locally in parts of the combustion chamber where the proportion of fuel is higher and the mixture is thus richer, potentially giving rise to soot during combustion.
  • Soot may for example also be formed by oil splash from the engine's lubrication reaching the combustion chamber, e.g. via the movements of the piston.
  • Metal fragments from wear and/or manufacture of the engine may for example give rise to particle formation.
  • the vehicle's fuel may be more or less “clean” and thus itself give rise to sundry particle formation during combustion.
  • soot particles are thus gathered up by the particle filter 202 by the exhaust flow being led through the filter structure, in which they are captured from the passing exhaust flow in order to be stored in the filter.
  • a particle filter can usually separate a very large proportion of the particles present in the exhaust flow.
  • OBD on-board diagnostics
  • Particle capture from the exhaust flow by means of particle filters is usually so effective that the amount of particles actually leaving the vehicle is in general very small when the filter is fully functional.
  • the location 221 indicated in FIG. 2 has the further disadvantage that at times when the filter malfunctions, e.g. because a mechanical fault suddenly occurs, causing a marked increase in particle emission, it is very difficult to predict how the exhaust flow path will change in such situations since, depending on the flow path, there will be no certainty that the sensor is so located that the raised particle contents will actually be detected.
  • the PM sensor is located according to the present invention upstream of the particle filter instead of downstream, as illustrated by the sensor 222 in FIG. 2 .
  • Such problems can be reduced or completely eliminated by the method according to the invention of using the sensor situated upstream of the filter to determine whether the vehicle's emissions are below prescribed levels.
  • a method 300 according to the present invention for determining a particle emission is illustrated in FIG. 3 .
  • the method is implemented in the control unit 208 and begins at step 301 by determining whether the vehicle's engine 101 has been started. If it has, the method moves on the step 302 , otherwise it stays at step 301 or ends.
  • Step 302 determines whether signals are being received from the PM sensor 202 .
  • the method stays at step 202 until sensor signals are received but not beyond the time when a timer t 1 reaches a time T 1 . If no sensor signals are received before the counter reaches T 1 , which may for example be part of a second or a suitable number of seconds, the method can move on to a step 303 for diagnosis of the sensor, see below. If, on the contrary, sensor signals are received within time T 1 , the method moves on to step 304 for determination of a particle content of the exhaust flow.
  • Step 304 determines a first particle content on the basis of the signals delivered by the PM sensor 222 . As the determination is by means of a PM sensor situated upstream of the particle filter 202 , a continuous flow of particles will be continually passing the sensor when the engine is in operation.
  • the particle content at the PM sensor 222 will be substantially greater than downstream of the filter, and the sensor's measurements according to the present invention will result in the delivery of a continuous signal.
  • This signal will be delivered more quickly, since the higher particle content means that the smallest amount of particles required for the sensor to indicate their presence will be reached more quickly.
  • the signal will also indicate a higher amount of particles, making both size determination and diagnosis easier.
  • the PM sensor 222 being situated in an environment where the exhaust flow has a higher particle content, its location upstream of the particle filter affords the further advantage of allowing it to be in a well-mixed and homogenous exhaust flow and thus be able to take measurements in a representative part of the exhaust flow.
  • the PM sensor is situated upstream of both DPF 202 and DOC 205 , but as exemplified below it might be at a number of different locations (but always upstream of the particle filter 202 ).
  • step 304 When a first particle content has been determined at step 304 on the basis of the signals delivered by the PM sensor, the method moves on to step 305 , in which the first particle content determined is compared with a second particle content.
  • step 305 If it is determined at step 305 that the particle content determined at step 304 is greater than said second particle content, the method moves on to step 307 for further investigation. It is for example possible for steps 301 - 305 to be repeated one or more times until they have been run through y times, and the respective number of times x is incremented each time the method moves to step 307 .
  • the method may for example go back to step 301 from step 307 when a timer t 2 has calculated a time T 2 , e.g. a suitable number of seconds. By this procedure it is possible to determine whether the raised particle content is only temporary before dropping back below a prescribed level. If raised levels persist after said plurality of determinations, i.e.
  • the method may move on to a step 308 in order if possible to establish by diagnosis the reason for the raised contents.
  • This diagnosis may for example be conducted by means of the diagnostic method described in the parallel Swedish patent application entitled “METHOD AND SYSTEM FOR DIAGNOSIS OF A COMBUSTION ENGINE” (“F ⁇ RFARANDE OCH SYSTEM F ⁇ R DIAGNOSTISERING AV EN F ⁇ RBR ⁇ NNINGSMOTOR”, application number 1151074-0) with the same inventor and filing date as the present application.
  • Said application proposes a method for diagnosis of a combustion engine pertaining to a vehicle whereby a particle content of an exhaust flow from said engine is determined at a location upstream of a particle filter by means of a PM sensor situated upstream of the filter.
  • Whether the engine is malfunctioning is determined on the basis of the particle content determined.
  • the method referred to makes it possible for malfunctions to be detected at a very early stage and for suitable remedial action to be taken. Faults which would perhaps otherwise not be detected until a substantially later time, e.g. on the occasion of a workshop visit, may by means of the method described in said patent application be detected substantially earlier.
  • a service indicator may for example be set in the vehicle's control system, e.g. together with a fault code for the too high particle emissions, with a view to the vehicle being taken in for servicing as soon as possible.
  • step 306 it is determined that the vehicle's emission levels are below the prescribed levels applicable to the vehicle.
  • step 306 it is thus possible to determine whether the particle content of the exhaust flow downstream of said particle filter fulfils a defined condition, e.g. that it is less than said second particle content.
  • the method then ends at step 309 .
  • Said second particle content may for example be the highest particle content which the vehicle is permitted to release by prevailing regulations, and may therefore be different for different vehicles, but also different for similar vehicles running in different jurisdictions which have different particle emission requirements. Emissions are usually standardised with respect to a specific running cycle, and said second particle content may for example be determined by the permissible amount of particles per kWh of work performed by the engine, i.e. the more work the engine performs, the greater the emissions allowed in the exhaust flow. Emission requirements are often expressed in particle mass per unit of engine work, e.g. kg/kWh, g/kWh or mg/kWh, and this engine work may for example take the form of power output developed or deliverable.
  • This second particle content may however also be a content higher than prevailing requirements.
  • Said second particle content may thus depend on various parameters and may for example be determined at step 305 as a function of one or more from among pressure before and after the particle filter, differential pressure across the filter, time, exhaust temperature and exhaust flow, such data possibly being for example used to determine a second particle content which meets prevailing emission requirements.
  • said second particle content at step 305 is very suitable for engines in which prescribed emission levels can be maintained even before particle filtration. Determining that the particle mass even before the particle filter is below statutory level means that the particle content after DPF will automatically also be kept below statutory level even if DPF malfunctions.
  • the invention thus makes it possible to monitor that requirements about particle emissions after the particle filter are complied with without any need for actual measurement of particle content after the filter.
  • said second particle content may be a value higher than prevailing requirements.
  • the second particle content may for example be set with respect to the filter's cleaning capacity, which may for example be determined theoretically or be measured. Said second particle content may thus be set to a level which, despite being higher than prescribed requirements, still provides assurance that the particle content actually leaving the vehicle will still be below prescribed levels.
  • Particles separated from the exhaust flow by means of the particle filter accumulate in the filter, which will thus fill with soot over time.
  • the filter has to be “emptied”, which is done by so-called regeneration, which will be familiar to one skilled in the art.
  • the filter's cleaning capacity may vary with how full it is, so said second particle content in one embodiment may also be arranged to vary with the filter's fullness, which may for example be determined on the basis of signals from a pressure sensor 209 which measures the differential pressure across the filter. The fuller the filter becomes, the greater will be the pressure difference across it.
  • said second particle content may therefore be arranged to depend on the differential pressure across the filter in that it may be arranged to decrease in step with increasing differential pressure.
  • particle emissions are approved on the basis of a single value.
  • a plurality of values are instead determined for said first particle content and may then be combined to arrive at an average value which is compared with said second particle content.
  • individual values may be allowed to exceed said second particle content so long as their combined value is less than said second particle content.
  • the method illustrated in FIG. 3 may also be repeated at certain intervals, e.g. once per second, once per minute or at some other shorter or longer suitable interval.
  • the present invention thus makes it possible to monitor that requirements concerning particle emissions after the particle filter are met without having to actually measure the particle content after the filter, even on engines where the particle content of the exhaust flow upstream of the filter does not meet prevailing requirements.
  • Locating the PM sensor upstream of the particle filter to monitor emission requirements has further advantages. Since the sensor is so situated that measurement signals will be continually delivered, its function may be verified by observing the signal delivered by it over time. So long as it delivers substantially continuous signals, or delivers for similar operating situations substantially the same signal, the sensor may be regarded as working properly. If on the contrary it suddenly indicates substantially lower emissions than normal for a given running situation, it may be assumed that the sensor is malfunctioning, and a service flag may for example be activated in the vehicle's control system to indicate a need for servicing.
  • the sensor may for example be of a type which delivers for example a voltage or current or presents a capacitance, inductance or resistance which varies with the presence of particles, in which case the control unit 208 may then use appropriate mathematical relationships or a table to convert measured values received to corresponding particle contents.
  • the sensor may however also be of a type with its own control logic, in which case this internal control logic will calculate a content which is then conveyed to the control unit, e.g. via the vehicle network or a dedicated cable.
  • the sensor may also be used to detect situations where the particle content of the exhaust flow suddenly exceeds a normal level or a regulation level. Even if the particle filter itself often provides assurance that requirements concerning actual emissions in the vehicle's surroundings are still complied with, the higher particle content nevertheless indicates that the engine is not fully functional, which is another situation where it is desirable that the vehicle come in for servicing as soon as possible to rectify the cause or causes of the increased particle content in the exhaust gases. This is described in more detail in the aforesaid parallel patent application entitled “METHOD AND SYSTEM FOR DIAGNOSIS OF A COMBUSTION ENGINE” (“F ⁇ RFARANDE OCH SYSTEM F ⁇ R DIAGNOSTISERING AV EN F ⁇ RBR ⁇ NNINGSMOTOR”).
  • the present invention affords the further advantage that active testing of sensor function can be performed.
  • the engine may for example be deliberately set to operating points which may be expected to result in substantially higher particle emissions.
  • the signals delivered by the sensor it can be determined whether they actually reflect the expected increase in the particle content of the exhaust flow. So long as expected changes in its signal occur, the sensor may also be assumed to be working properly. If the signals do not increase despite the increased particle emissions due to the running situation, the sensor may be assumed to be malfunctioning.
  • the PM sensor 222 upstream of the particle filter affords also the advantage that it can with greater certainty be so situated as to cause its signals to be representative of the exhaust flow produced by the engine.
  • the sensor may for example be situated, as in FIG. 2 , after a turbo unit 220 from which the exhaust flow is usually delivered in a predictable way. It may for example also be situated downstream of DOC 205 but upstream of the particle filter 202 .
  • the SCR catalyst 203 is downstream of the particle filter, but in one embodiment it is instead upstream of DPF 202 , in which case the sensor may be downstream or upstream of the catalyst.
  • the vehicle may also be equipped with a so-called exhaust brake which the sensor 222 may for example be upstream of. It may also be situated in the EGR feedback of part of the exhaust flow as is commonly the case in vehicles of the above kind, since this part of the exhaust flow is representative of the composition of the total exhaust flow.
  • the sensor 222 may for example also be situated upstream of the turbo unit 220 .
  • the turbo unit may be of the type with fixed geometry (FGT) or of the type with variable geometry (VGT) and be provided with turbines to feed power back to crankshafts (turbo compound) or some other part of the power train.
  • the vehicle may also be provided with a so-called ammonia slip catalyst (ASC) which the PM sensor may be situated upstream or downstream of. There are thus a large number of possible locations for the PM sensor upstream of the particle filter.
  • ASC ammonia slip catalyst
  • said second particle content has hitherto been referred to in relation to various requirements, but it may also be set, e.g. in jurisdictions where there are no regulatory requirements, to a value determined by the vehicle's manufacturer. It may for example be based on a value which provides assurance of good engine function.
  • the present invention is exemplified above in relation to vehicles.
  • the invention is nevertheless also applicable to any other means of transport/processes in which particle filter systems as above are applicable, e.g. watercraft or aircraft with combustion processes as above.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
US14/357,826 2011-11-14 2012-11-13 Method and system pertaining to monitoring particle emissions in combustion engine exhausts Abandoned US20140290217A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE1151073-2 2011-11-14
SE1151073A SE536180C2 (sv) 2011-11-14 2011-11-14 Förfarande och system för bestämning av partikelutsläpp vid en förbränningsmotor
PCT/SE2012/051240 WO2013074022A1 (en) 2011-11-14 2012-11-13 Method and system pertaining to monitoring particle emissions in combustion engine exhausts

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US20140290217A1 true US20140290217A1 (en) 2014-10-02

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EP (1) EP2780563B1 (pt)
CN (1) CN103930660A (pt)
BR (1) BR112014011485A2 (pt)
RU (1) RU2014124141A (pt)
SE (1) SE536180C2 (pt)
WO (1) WO2013074022A1 (pt)

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CN113686585A (zh) * 2021-08-10 2021-11-23 一汽解放汽车有限公司 车辆排放物监测方法、装置、计算机设备和存储介质

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EP2780563B1 (en) 2019-07-24
SE536180C2 (sv) 2013-06-18
SE1151073A1 (sv) 2013-05-15
BR112014011485A2 (pt) 2017-05-09
CN103930660A (zh) 2014-07-16
EP2780563A1 (en) 2014-09-24
EP2780563A4 (en) 2015-11-18
WO2013074022A1 (en) 2013-05-23
RU2014124141A (ru) 2015-12-27

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