Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/22—Devices for withdrawing samples in the gaseous state
  • G01N1/2247—Sampling from a flowing stream of gas
  • G01N1/2252—Sampling from a flowing stream of gas in a vehicle 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
  • F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• • 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
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
• • 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
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
  • F01N13/0093—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series the purifying devices are of the same type
• • 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
  • F01N3/101—Three-way catalysts
• • 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
  • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
  • F01N3/106—Auxiliary oxidation catalysts
• • 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
  • F01N3/18—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 characterised by methods of operation; Control
  • F01N3/20—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 characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
  • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
  • F01N3/2013—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means
  • F01N3/2026—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means directly electrifying the catalyst substrate, i.e. heating the electrically conductive catalyst substrate by joule effect
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/021—Introducing corrections for particular conditions exterior to the engine
  • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
• • 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
  • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
  • F01N2560/025—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting O2, e.g. lambda sensors
• • 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
• • 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
  • F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/04—Introducing corrections for particular operating conditions
  • F02D41/12—Introducing corrections for particular operating conditions for deceleration
  • F02D41/123—Introducing corrections for particular operating conditions for deceleration the fuel injection being cut-off
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/06—Investigating concentration of particle suspensions
• • 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
  • Y02T10/12—Improving ICE efficiencies
• • 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 an exhaust particulate matter measuring apparatus that measures the amount of particulate matter present in exhaust gas.
• a conventional direct-injection type of internal combustion engine in which fuel is injected directly into a combustion chamber, rather than into an intake port.
• this direct-injection type internal combustion engine when the intake valve is open, air is drawn into the combustion chamber from the intake port and compressed by a piston, an injector directly injecting fuel to this high-pressure air.
• the high-pressure air in the combustion chamber and the fuel mist are mixed, and the resulting air-fuel mixture is ignited by a spark plug to cause an explosion to generate driving power.
• the exhaust valve is open, the exhaust gas after combustion is discharged from an exhaust port.
• the exhaust gas discharged from the combustion chamber includes harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) 5 a three-way catalyst is provided in the exhaust passage to purify the harmful substances.
• CO carbon monoxide
• HC hydrocarbons
• NOx nitrogen oxides
• a three-way catalyst is provided in the exhaust passage to purify the harmful substances.
• fuel is directly injected into the air in the combustion chamber, which reaches a high temperature by high compression, and ignited. Because a large amount of fuel is injected into the combustion chamber in particular in order to raise the engine output at a high load, the combustion chamber could become oxygen-deficient and particulate matter (PM) such as black smoke might be included in the exhaust gas.
• PM particulate matter
• a sensor for determining the soot concentration forms a soot sensor is a soot sensor in which an electrical heating member and an electrical temperature probe are provided in a porous molded member, wherein the electrical heating member combusts soot particles that have settled onto the molded member, and the generation of heat caused by the combustion is measured by the electrical temperature probe, the temperature rise being evaluated as a direct criterion using the combustion amount of the soot particles and the soot amount being determined from that evaluation.
• the present invention provides an exhaust particulate matter measuring apparatus that accurately measures that amount of particulate matter present in exhaust gas.
• An aspect of the present invention relates to an exhaust particulate matter measuring apparatus.
• the exhaust particulate matter measuring apparatus has an oxidation catalyst, disposed in an exhaust passage of an internal combustion engine; a heating means for heating the oxidation catalyst; a temperature sensor for measuring a temperature of the oxidation catalyst; and a sediment amount calculation means for calculating a sediment amount of exhaust particulate matter in response to a degree of temperature rise when the heating means heats the oxidation catalyst.
• the oxidation catalyst may carry an oxygen-storing agent.
• the exhaust particulate matter measuring apparatus by carrying an oxygen-storing agent on an oxidation catalyst disposed in the exhaust passage of the internal combustion engine and providing a heating means to heat the oxidation catalyst, a temperature sensor to measure the temperature of the oxidation catalyst, and a sediment amount calculation means for calculating a sediment amount of exhaust particulate matter in response to the degree of temperature rise when the heating means heats the oxidation catalyst, the following effect is achieved.
• the oxygen-storing agent of the oxidation catalyst occludes oxygen that usually exists in the exhaust gas
• the heating means when the oxidation catalyst is heated by the heating means the exhaust particulate matter captured by the oxidation catalyst is properly combusted, along with the oxygen occluded by the oxygen-storing agent, and the sediment amount calculation means can accurately calculate the sediment amount of exhaust particulate matter, in accordance with the degree of temperature rise at that time.
• the oxidation catalyst may be disposed downstream in an exhaust gas flow direction from a three-way catalyst disposed in the exhaust passage and upstream from a muffler disposed in the exhaust passage.
• the sediment amount calculation means may estimate an amount of oxygen occluded by the oxygen-storing agent based on a fuel cut control duration time of the internal combustion engine and an intake air amount, and when the amount of oxygen occluded reaches or exceeds a prescribed value, the heating means may heat the oxygen catalyst to calculate a sediment amount of exhaust particulate matter.
• an oxidation sensor may be disposed in the vicinity of the oxidation catalyst in the exhaust passage
• the sediment amount calculation means estimates an amount of oxygen occluded by the oxygen-storing agent based on a detected result of the oxidation sensor, and when the amount of oxygen occluded reaches or exceeds a prescribed value, the heating means may heat the oxygen catalyst to calculate the sediment amount of exhaust particulate matter.
• the sediment amount calculation means may heat the oxidation catalyst by the heating means to calculate the sediment amount of the exhaust particulate matter when the internal combustion engine executes a fuel cut control.
• the sediment amount calculation means may heat the oxidation catalyst using the heating means to combust the exhaust particle matter, and when the temperature of the oxidation catalyst is as low as or lower than the temperature at which the exhaust particulate matter cannot be combusted, accumulation of the intake ah" amount may be started, and when the accumulated amount of intake air is larger than a prescribed value, the sediment amount calculation means may heat the oxidation catalyst using the heating means to calculate the sediment amount of the exhaust particulate matter.
• the foregoing exhaust particulate matter measuring apparatus may further include an exhaust temperature sensor disposed in a vicinity of the oxidation catalyst, wherein the sediment amount calculation means, when the exhaust gas temperature reaches at least a combustion temperature at which it is possible for the exhaust particulate matter to be combusted, cancels the accumulated value of intake air amount and restarts the calculation of the intake air amount.
• the sediment amount calculation means prohibits rich operation of the internal combustion engine during heating the oxidation catalyst using the heating means to calculate the sediment amount of the exhaust particulate matter.
• FIG. 1 is a drawing showing the general configuration of an internal combustion engine to which an exhaust particulate matter measuring apparatus according to a first embodiment of the present invention is applied;
• FIG. 2 is a simplified drawing showing the exhaust particulate matter measuring apparatus according to the first embodiment
• FIG. 3 is a graph showing the relationship between the ceria additive amount and the sensor surface area in the exhaust particulate matter measuring apparatus according to the first embodiment
• FIG. 4 is graph showing the relationship between the ceria additive amount and the exhaust amount in the exhaust particulate matter measuring apparatus according to the first embodiment
• FIG. 5 is a graph showing the relationship between the heater temperature and the sensor temperature in the exhaust particulate matter measuring apparatus according to the first embodiment
• FIG. 6 is a flowchart showing the measurement control in the exhaust particulate matter measuring apparatus according to the first embodiment
• FIG. 7 is a drawing showing the general configuration of an internal combustion engine to which an exhaust particulate matter measuring apparatus according to a second embodiment of the present invention is applied;
• FIG. 8 is a flowchart showing the measurement control in the exhaust particulate matter measuring apparatus according to the second embodiment of the present invention;
• FIG. 9A and 9B are a flowchart showing the measurement control in an exhaust particulate matter measuring apparatus according to a third embodiment of the present invention.
• FIG. 10 is a flowchart showing the measurement control in an exhaust particulate matter measuring apparatus according to a fourth embodiment of the present invention.
• FIG. 11 is a flowchart showing the measurement control in an exhaust particulate matter measuring apparatus according to a fifth embodiment of the present invention.
• FIG. 1 is a drawing showing the general configuration of an internal combustion engine to which an exhaust particulate matter measuring apparatus according to a first embodiment of the present invention is applied.
• FIG. 2 is a simplified drawing showing the exhaust particulate matter measuring apparatus according to the first embodiment.
• FIG. 3 is a graph showing the relationship between the ceria additive amount and the sensor surface area in the exhaust particulate matter measuring apparatus according to the first embodiment.
• FIG. 4 is graph showing the relationship between the ceria additive amount and the exhaust amount in the exhaust particulate matter measuring apparatus according to the first embodiment.
• FIG. 5 is a graph showing the relationship between the heater temperature and the sensor temperature in the exhaust particulate matter measuring apparatus according to the first embodiment.
• FIG. 6 is a flowchart showing the measurement control in the exhaust particulate matter measuring apparatus according to the first embodiment.
• the engine 10 may be a four-cylinder direct-injection type engine, in which a cylinder head 12 is fitted tightly onto a cylinder block 11, wherein a pistons 14 are fitted into a plurality of cylinder bores 13 formed in the cylinder block 11 to enable up-and-down movement within the cylinder block 11.
• a crankcase 15 is fitted tightly to the bottom of the cylinder block 11.
• a crankshaft 16 is rotatably supported inside the crankcase 15, and each of the pistons 14 is linked to the crankshaft 16 via a connecting rod 17.
• FIG. 1 only one cylinder and cylinder bore of four cylinders is shown.
• a combustion chamber 18 is formed by the wall surface of the cylinder bore 13 of the cylinder block 11, the lower surface of the cylinder head 12, and the upper surface of the piston 14,
• This combustion chamber 18 is a pent-roof shaped, in which an upper part (lower surface of the cylinder head 12) is inclined so that the center part thereof is high.
• An intake port 19 and an exhaust port 20 are formed in the upper part of the combustion chamber 18, that is, in the lower surface of the cylinder head 12, and the lower end parts of an intake valve 21 and an exhaust valve 22 are provided at the lower ends of the intake port 19 and the exhaust port 20, respectively.
• the intake valve 21 and the exhaust valve 22 are supported to enable free movement along the axial direction of the cylinder head 12, and urged in the direction such that the intake port 19 and the exhaust port 20 are blocked (upward in FIG. 1).
• An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported in the cylinder head 12, and an intake cam 25 and an exhaust cam 26 make contact with the upper end parts of the intake valve 21 and the exhaust valve 22, respectively.
• an timing chain is wound around the crankshaft sprocket fixed to the crankshaft 16 and camshaft sprockets fixed, respectively, to the intake camshaft 23 and the exhaust camshaft 24, enabling the camshaft 16 to move in concert with the intake camshaft 23 and the exhaust camshaft 24.
• the intake cam 25 and the exhaust cam 26 move the intake valve 21 and the exhaust valve 22 up and down with a prescribed timing to open and close the intake port 19 and the exhaust port 20.
• the intake port 19 communicates with the combustion chamber 18, and the combustion chamber 18 communicates with the exhaust port 20.
• the intake camshaft 23 and the exhaust camshaft 24 are set to make one rotation (360°) during two rotations (720°) of the crankshaft 16. For this reason, the engine 10 executes the four strokes of intake stroke, compression stroke, expansion stroke, and exhaust stroke during two rotations of the crankshaft 16, during which the intake camshaft 23 and the exhaust camshaft 24 rotate one time.
• variable-valve mechanisms of the engine 10 are intake/exhaust variable valve timing-intelligent mechanisms (hereinafter VVT mechanisms) 27, 28 that control the intake valve 21 and the exhaust valve 22 with the optimum timing, in response to an operating condition.
• the intake and exhaust variable valve timing mechanisms 27, 28 have VVT controllers 29, 30 on the shaft end parts of the intake camshaft 23 and the exhaust camshaft 24. Hydraulic pressure from oil control valves 31, 32 is caused to act on an advance angle chamber and a retard angle chamber (not shown) of the VVT controllers 29, 30 to change the phase of the camshafts 23, 24 with respect to the cam sprocket, thereby enabling advancing angle or retarding angle of the timing of opening and closing the intake valve 21 and the exhaust valve 22.
• the intake and exhaust variable valve timing mechanisms 27, 28 advance or retard the timing of opening and closing to keep the operating angle (opening time period) of the intake valve 21 and the exhaust valve 22 constant.
• Cam position sensors 33, 34 are provided on the intake camshaft 23 and exhaust camshaft 24 to detect the rotational phase thereof.
• a surge tank 36 is connected to the intake port 19 via an intake manifold 35, and an intake pipe 37 is connected to the surge tank 36.
• An air cleaner 38 is mounted to an air intake port of the intake pipe 37.
• An electronic throttle apparatus 40 having a throttle valve 39 is provided downstream from the air cleaner 38.
• An injector 41 that injects fuel directly into the combustion chamber 18 is attached to the cylinder head 12, the injector 41 being positioned on the intake port 19 side and disposed at a prescribed inclination angle with respect to the up-down direction.
• the injectors 41 attached to each cylinder are linked to a delivery pipe 42, and a high-pressure fuel pump 44 is connected to the delivery pipe 42 via a high-pressure fuel supply pipe 43. Additionally, a spark plug 45 that ignites the air-fuel mixture is provided at the top of the combustion 1240
• An exhaust pipe (exhaust passage) 47 is connected to the exhaust port 20 via an exhaust manifold 46.
• An electronic control unit 51 (hereinafter, ECU 51) that controls, for example, the injector 41 and the spark plug 45 is mounted aboard the vehicle, and an air flow sensor 52 and intake temperature sensor 53 are provided in an upstream-side of the intake pipe (intake passage) 37.
• An intake pressure sensor 54 is also provided in the surge tank 36, and the measured intake air amount, intake temperature, and intake pressure (intake pipe negative pressure) are output to the ECU 51.
• a throttle position sensor 55 is attached to the electronic throttle apparatus 40 and outputs the current throttle opening amount to the ECU 51, and an accelerator sensor 56 outputs the current accelerator depression amount to the ECU 51.
• a crank angle sensor 57 outputs the detected crank angles of each cylinder to the ECU 51, and the ECU 51 distinguishes the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in the cylinders from the detected crank angle, and also calculates the engine speed.
• a coolant temperature sensor 58 that detects the engine coolant temperature is provided in the cylinder block 11 and outputs the detected engine coolant temperature to the ECU 51.
• a fuel pressure sensor 59 that detects the fuel pressure is provided in the delivery pipe 42 that communicates with the injectors 41, and outputs the detected fuel pressure to the ECU 51.
• Oxygen sensors 60, 61 that detect oxygen concentration of the exhaust gas are provide upstream and downstream from the three-way catalyst 48 in the exhaust pipe 47, and output the detected oxygen concentrations to the ECU 51.
• the ECU 51 therefore, drives the high-pressure pump 44 to achieve a prescribed fuel pressure based on the detected fuel pressure, determines such items as the fuel injection amount (fuel injection time), the fuel injection timing, and the ignition timing, based on the engine operating conditions such as the detected intake air amount, intake air temperature, intake air pressure, throttle opening amount, accelerator depression amount, engine speed, and engine coolant temperature, and drives the injector 41 and spark plug 45 to execute fuel injection and ignition.
• the ECU 51 executes a feedback control based on the oxygen concentration of the detected exhaust gas so as to correct the fuel injection amount to achieve a stoichiometric air-fuel ratio.
• the ECU 51 controls the intake and exhaust variable valve timing mechanisms 27, 28 based on the engine operating condition. Specifically, when the engine is started at a low temperature, and during idling or light-load operation, by eliminating overlap between the period of time the exhaust valve 22 is closed and the period of time the intake valve 21 is open, it is possible to reduce the amount of blowback of exhaust gas to intake port 19 or the combustion chamber 18 and to improve combustion stability and fuel economy. At a medium load, by making this overlap large, the internal EGR ratio is increased and the exhaust gas purification efficiency is improved, and it is also possible to reduce the pumping loss and improve the fuel economy.
• a PM (particulate matter) sensor 62 that measures the amount of particulate matter in the exhaust gas, specifically the amount of particulate matter such as black smoke, is provided between the three-way catalyst 49 and the muffler 50 in the exhaust pipe 47. The PM sensor 62, as shown in FIG.
• oxidation catalyst 71 is box-shaped, and has an oxidation catalyst 71 and an electrical heater 72 that heats the oxidation catalyst 71, the oxidation catalyst 71 and electrical heater 72 that are stacked together.
• a temperature sensor 73 that measures the temperature of the oxidation catalyst 71 is interposed between the oxidation catalyst 71 and the electrical heater 72.
• the oxidation catalyst 71 has formed in it, for example, a large number of exhaust flow passages by making a ceramic porous, wherein a metal such as platinum or palladium is carried as the catalytic metal of the oxidation catalyst 71.
• the oxidation catalyst 71 carries ceria as an oxygen-storing agent that occludes oxygen contained in the exhaust gas.
• the amount of ceria additive as shown in FIG. 3, is set in accordance with the surface area of the PM sensor 62 (oxidation catalyst 71) and, as shown in FIG. 4, is set in accordance with the displacement of the engine 10.
• the PM sensor 62 therefore, converts HC and CO components in the exhaust gas by oxidation (reaction with oxygen) to CO 2 and H 2 O and, by passing the exhaust gas through the porous member, and captures particulate matter, and in particular smoke particles in the exhaust gas. Because the oxidation catalyst 71 carries ceria, it can occlude oxygen in the exhaust gas.
• the ECU 51 calculates the sediment amount of the exhaust particulate matter in accordance with the degree of temperature rise at that time.
• the temperature of the oxidation catalyst 71 detected by the temperature sensor increases proportionately, as indicated by the solid line in FIG. 5.
• the temperature of the oxidation catalyst 71 detected by the temperature sensor rises suddenly, as shown by the single-dot-dash line in FIG. 5.
• the PM sensor 62 is disposed downstream from three-way catalyst 49 disposed in the exhaust pipe 47 in the exhaust gas flow direction and also upstream from the muffler 50 in the exhaust gas flow direction. In this case, when the engine 10 is operating under a high load, because the exhaust gas temperature rises to 650 0 C or greater, at which the exhaust particulate matter is combusted, even the exhaust particulate matter settled in the PM sensor 62 is combusted by the high-temperature exhaust gas, making it impossible to measure the sediment amount.
• the PM sensor 62 is disposed at a downstream location a prescribed distance from three-way catalyst 49 in the exhaust gas flow direction, at which the exhaust gas temperature is reduced to a temperature, for example 600 0 C 5 at which the exhaust particulate matter can not be combusted. Because the downstream portion of the exhaust pipe 47 is exposed to the atmosphere, condensed water may come in contact with the PM sensor 62 when the engine 10 is cold-started and damage the sensor. Thus, the PM sensor 62 is disposed at prescribed distance upstream from the muffler 50 attached to the end part of the exhaust pipe 47 in the exhaust gas flow direction.
• the ECU 51 determines whether the engine 10 is warmed-up. That is, the ECU 51 determines whether the engine coolant temperature detected by the coolant temperature sensor 58 has reached at least a prescribed engine warm-up coolant temperature. At this point, if the determination is made that the engine coolant temperature has not reached the engine warm-up coolant temperature, nothing is done and the routine ends. If, however, the determination is made that the engine coolant temperature has reached at least the engine warm-up coolant temperature, the process then proceeds to step S 12.
• the ECU 51 electrically powers the electrical heater 72 in the PM sensor 62 to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71. Then, at step S 13 a determination is made of whether the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62 has been completely combusted. In this case, although when electrical heater 72 is electrically powered, the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62 is combusted, and the temperature of the oxidation catalyst 71 (sensor temperature) rises suddenly indicated by the single-dot-dash line in FIG.
• step Sl 4 the ECU 51 stops the electrical power to the electrical heater 72 in the PM sensor 62.
• step Sl 5 the temperature sensor 73 measures the temperature of the oxidation catalyst 71, and at step Sl 6 a determination is made as to whether the temperature tpvi of the oxidation catalyst 71 measured by the temperature sensor 73 is as low as or lower than the temperature t A at which the exhaust particulate matter cannot be combusted.
• steps S15 and S 16 is repeated until a determination is made at step Sl 6 that the temperature tp M of the oxidation catalyst 71 has decreased to no greater than the temperature t A at which the exhaust particulate matter cannot be combusted.
• step S 17 accumulation of the intake air amount is started.
• the intake air amount detected by the air flow sensor 52 is accumulated from the point at which the temperature tp M of the oxidation catalyst 71 has decreased to no greater than the temperature t A at which the exhaust particulate matter cannot be combusted.
• step S 18 a determination is made of whether the accumulated amount of intake air ⁇ ga is larger than a prescribed value A. The processing of steps S17 and Sl 8 is repeated until the determination is made at step Sl 8 that the accumulated amount of intake air ⁇ ga has become greater than the prescribed value A. If the determination is made at step Sl 8 that the accumulated amount of intake air
• the ECU 51 determines whether oxygen is present in the area surrounding the PM sensor 62.
• the temperature tp M of the oxidation catalyst 71 decreases to no greater than the temperature I A at which the exhaust particulate matter cannot be combusted, during a prescribed air amount accumulation time period after the start of accumulation of the intake air amount detected by the air flow sensor 52, a determination is made of whether the environment surrounding the ceria of the oxidation catalyst 71 is one that enables the occlusion of oxygen.
• the oxygen occlusion amount of the ceria is estimated by determining whether the fuel cut control duration time or accumulation time has reached or exceeded a prescribed time and also the accumulated intake air amount has reached or exceeded a prescribed accumulated value.
• step S 19 if the fuel cut control duration time or accumulation time has not reached or exceeded a prescribed time or the accumulated intake air amount has not reached or exceeded a prescribed accumulated value, the determination is made that the ceria of the oxidation catalyst 71 has not occluded a sufficient amount of oxygen, and the processing of steps S 17 to S19 is repeated, If, however, at step 19, the fuel cut control duration time or accumulation time has reached or exceeded a prescribed time and also the accumulated intake air amount has reached or exceeded a prescribed accumulated value, the determination is made that the ceria of the oxidation catalyst 71 has occluded a sufficient amount of oxygen, and processing proceeds to step S20.
• the ECU 51 electrically powers the electrical heater 72 in the PM sensor 62 to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71.
• the sediment amount of the exhaust particulate matter is calculated in accordance with the degree of temperature rise in the oxidation catalyst 71 at that time. That is, the sediment amount of the exhaust particulate matter is calculated using a prescribed map based on the accumulated intake air amount measured during the above-noted period of time of accumulation of intake air amount and the amount of temperature rise in the oxidation catalyst 71 detected by the temperature sensor 73.
• step S22 a determination is made of whether, by completely combusting the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62, the calculation of the sediment amount of the exhaust particulate matter has ended.
• the determination of ending is made by the decrease of the temperature (sensor temperature) of the oxidation catalyst 71 that had risen suddenly by the combustion of exhaust particulate matter settled in the oxidation catalyst 71, and return to the change indicated by the solid line in FIG. 5.
• the processing of steps S20 to S22 is repeated until the determination is made at step S22 that the processing to calculate the sediment amount of the exhaust particulate matter has ended.
• step S23 the ECU 51 stops electrical power to the electrical heater 72 in the PM sensor 62, and all processing is ended.
• the exhaust particulate matter measuring apparatus of the first embodiment is configured to provide, between the three-way catalyst 49 and the muffler 50 in the exhaust pipe 47, a PM sensor 62 that measures the amount of particulate matter in the exhaust gas, the PM sensor 62 being fixed by stacking the oxidation catalyst 71 and the electrical heater 72 together, and a temperature sensor 73 that measures the temperature of the oxidation catalyst 71 being interposed between the oxidation catalyst 71 and the electrical heater 72.
• the oxidation catalyst 71 carries ceria as an oxygen-storing agent that occludes oxygen in the exhaust gas, and the ECU 51 calculates ' the sediment amount of the exhaust particulate matter based on the amount of temperature rise when the electrical heater 72 heats the oxidation catalyst 71, and the accumulated intake air amount.
• the ceria in the oxidation catalyst 71 constantly occludes oxygen present in the exhaust gas and, when the oxidation catalyst 71 is heated by the electrical heater 72, the exhaust particulate matter settled in the oxidation catalyst 71 can be properly combusted with the oxygen occluded in the ceria, and the ECU 51 accurately calculates the sediment amount of exhaust particulate matter, based on the amount of temperature rise at this time and the accumulate value of intake air amount.
• the ECU 51 electrically powering the electrical heater 72 in the PM sensor 62 to heat the oxidation catalyst 71, if the temperature tp M of the oxidation catalyst 71 decreases to no greater than the temperature tA at which the exhaust particulate matter cannot be combusted, the processing to accumulate the intake air amount detected by the exhaust air flow sensor 52 is started. It is therefore possible before measurement to combust the exhaust particulate matter settled in the oxidation catalyst 71, and also possible to reduce measurement error by decreasing the temperature of the oxidation catalyst 71 to a temperature at which the exhaust particulate matter is not combusted.
• the ECU 51 estimates the amount of oxygen occluded by the ceria. Therefore, estimation of the amount of oxygen occluded by the ceria based on the fuel cut control and intake air amount, makes it possible to properly execute the calculation of the sediment amount of exhaust particulate matter.
• the PM sensor 62 is disposed downstream from three-way catalyst 49 disposed in the exhaust pipe 47 in the exhaust gas flow direction and also upstream from the muffler 50 in the exhaust gas flow direction. Therefore, even if the engine 10 is operated at a high load and the exhaust gas temperature rises to 650 0 C or greater, at which the exhaust particulate matter is combusted, before the exhaust gas reaches the PM sensor 62 the temperature thereof decreases to a temperature at which exhaust particulate matter cannot be combusted, thereby enabling proper calculation of the sediment amount of exhaust particulate matter. Also, even if the engine 10 is cold started, condensed water does not reach the PM sensor 62, thereby preventing damage thereto.
• FIG. 7 is a drawing showing the general configuration of an internal combustion engine to which an exhaust particulate matter measuring apparatus according to the second embodiment of the present invention is applied and
• FIG. 8 is a flowchart showing the measurement control in the exhaust particulate matter measuring apparatus according to the second embodiment of the present invention.
• Members of the second embodiment having the same function as members described with regard to the first embodiment are referred to by the same numerals and are not repeatedly herein.
• the PM sensor 62 that measures the amount of particulate matter in the exhaust gas is provided between the three-way catalyst 49 and the muffler 50 in the exhaust pipe 47.
• This PM sensor 62 as shown in FIG. 2, has an oxidation catalyst 71 and an electrical heater 72, and a temperature sensor 73, and the oxidation catalyst 71 carries ceria, which occludes oxygen in the exhaust gas.
• an oxygen sensor (O 2 sensor) 63 is disposed in the vicinity of the PM sensor 62.
• the PM sensor 62 therefore, can capture particulate matter, particularly particles of soot, in the exhaust gas that flows through the exhaust pipe 47, and the oxidation catalyst 71 carries ceria, which can occlude the oxygen in the exhaust gas.
• the oxidation catalyst 71 With exhaust particulate matter captured by the PM sensor 62 and settled up to a prescribed amount and also when the occluded oxygen amount in the oxidation catalyst 71 is sufficient, based on the detection result of the oxygen sensor 63, when the electrical heater 72 is electrically powered to heat the oxidation catalyst 71, the exhaust particulate matter sediment is combusted using the oxygen that is occluded in the ceria by heating the oxidation catalyst 71, the ECU 51, as a sediment amount calculation means, calculates the sediment amount of the exhaust particulate matter in accordance with the degree of temperature rise at that time.
• the method of measuring the exhaust particulate matter with the exhaust particulate matter measuring apparatus according to the second embodiment is described in detail below, with reference being made to the
• the electrical heater 72 in the PM sensor 62 is electrically powered to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71.
• step S34 the electrical power to the electrical heater 72 in the PM sensor 62 is stopped. Then, at step S35 the temperature sensor 73 measures the temperature of the oxidation catalyst 71, and, at step S36, a determination is made as to whether the temperature tp M of the oxidation catalyst 71 measured by the temperature sensor 73 is as low as or lower than the temperature t A at which the exhaust particulate matter cannot be combusted.
• step S37 accumulation of the intake air amount is started. Then, at step S38, a determination is made of whether the accumulated amount of intake air ⁇ ga is larger than a prescribed value A.
• step S38 If the determination is made at step S38 that the accumulated amount of intake air
• the oxidation catalyst 71 of the PM sensor 62 carries ceria, after the temperature tp M of the oxidation catalyst 71 decreases to no greater than the temperature t A at which the exhaust particulate matter cannot be combusted, during a prescribed air amount accumulation time period after the start of accumulation of the intake air amount detected by the air flow sensor 52, a determination is made of whether the environment surrounding the ceria of the oxidation catalyst 71 is one that enables the occlusion of oxygen. That is, during this air amount accumulation time period, the amount of oxygen occluded by the ceria is estimated based on the history of the oxygen sensor 63 detecting oxygen.
• an oxygen sensor 63 detects the oxygen concentration based on an electromotive force generated in response to the oxygen concentration in the exhaust gas. That is, when exhaust gas is introduced into the internal detection element, a difference in oxygen concentration occurs between the inside platinum electrode and the outside platinum electrode, and oxygen ions flow from the inside platinum electrode, which has a high oxygen concentration, through a solid-state zirconia electrolyte, to the outside platinum electrode, which has a low oxygen concentration, thereby generating an electromotive force.
• step S39 if, in the air amount accumulation time, based on the electromotive force generated at the oxygen sensor 63, the time during which the exhaust gas is in the lean condition has reached at least a prescribed period of time, the determination is made that the ceria of the oxidation catalyst 71 has occluded a sufficient amount of oxygen.
• processing proceeds to step S40.
• step S40 the electrical heater 72 in the PM sensor 62 is electrically powered to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71.
• the sediment amount of the exhaust particulate matter is calculated in accordance with the degree of temperature rise in the oxidation catalyst 71 at that time. That is, the sediment amount of the exhaust particulate matter is calculated using a map of the accumulated intake air amount measured during the above-noted period of time of accumulation of intake air amount and the amount of temperature rise in the oxidation catalyst 71 detected by the temperature sensor 73.
• a determination is made of whether, by completely combusting the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62, the calculation of the sediment amount of the exhaust particulate matter has ended.
• the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62 is combusted and the sediment amount of exhaust particulate matter is calculated based on the change in temperature at that time, even if oxygen is not present in the exhaust gas flowing in the area around the oxidation catalyst 71, the oxygen occluded by the ceria can be used to reliably combust the exhaust particulate matter, thereby enabling proper calculation of the sediment amount of the exhaust particulate matter.
• the exhaust particulate matter measuring apparatus of the second embodiment is configured to provide, in the exhaust pipe 47, a PM sensor 62 that measures the amount of particulate matter in the exhaust gas, the PM sensor 62 being fixed by stacking the oxidation catalyst 71 and the electrical heater 72 together, and a temperature sensor 73 that measures the temperature of the oxidation catalyst 71 being interposed between the oxidation catalyst 71 and the electrical heater 72.
• the oxidation catalyst 71 carries ceria as an oxygen-storing agent that occludes oxygen in the exhaust gas, and the ECU 51 determines, based on the detection result from the oxygen sensor 63, whether the ceria has occluded a sufficient amount of oxygen and, when the determination is made that the ceria has occluded a sufficient amount of oxygen, the ECU 51 calculates the sediment amount of the exhaust particulate matter based on the amount of temperature rise when the oxidation catalyst 71 is heated by the electrical heater 72, and the accumulated intake air amount.
• the ceria in the oxidation catalyst 71 constantly occludes oxygen present in the exhaust gas and verification can be made, based on the detection result from the oxygen sensor 63, of whether the ceria has occluded a sufficient amount of oxygen.
• the oxidation catalyst 71 is heated by the electrical heater 72, the exhaust particulate matter settled in the oxidation catalyst 71 can be properly combusted with the oxygen occluded in the ceria, and the ECU 51 accurately calculates the sediment amount of exhaust particulate matter, based on the amount of temperature rise at this time and the accumulate value of intake air amount.
• FIG. 9 A and 9B are a flowchart of the measurement control of the exhaust particulate matter measuring apparatus according to the third embodiment of the present invention.
• the overall constitution of the exhaust particulate matter measuring apparatus of the third embodiment is substantially the same as that of the above-described embodiments.
• the third embodiment will be described using FIG. 1 and FIG. 2, and members having the same function as those members of the first and second embodiments already are referred to by the same numerals and are not repeatedly described herein.
• the PM sensor 62 that measures the amount of particulate matter in the exhaust gas is provided between the three-way catalyst 49 and the muffler 50 in the exhaust pipe 47.
• This PM sensor 62 as shown in FIG. 2, has an oxidation catalyst 71 and an electrical heater 72, and the temperature sensor 73, and the oxidation catalyst 71 carries ceria, which occludes oxygen in the exhaust gas.
• a temperature sensor 73 that detects the temperature within the PM sensor 62 is applied as an exhaust temperature sensor to measure the exhaust gas temperature.
• the PM sensor 62 can capture particulate matter, and particularly soot particles, in the exhaust gas flowing through the exhaust pipe 47, and the ceria carried by the oxidation catalyst 71 can occlude oxygen in the exhaust gas.
• the ECU 51 calculates the sediment amount of the exhaust particulate matter in accordance with the degree of temperature rise at that time. This embodiment cancels the accumulated amount of air intake and re-starts the accumulation of the intake air amount when the temperature of the exhaust gas detected by the temperature sensor 73 reaches at least the combustion temperature at which the exhaust particulate matter can be combusted.
• step S51 a determination is made of whether the engine 10 is completed warmed-up, that is, whether the engine coolant temperature detected by the coolant temperature sensor 58 is at least a prescribed engine warm-up coolant temperature.
• the electrical heater 72 in the PM sensor 62 is electrically powered to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71.
• step S53 a determination is made of whether the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62 has been completely combusted, based on the temperature change in the oxidation catalyst 71. If the determination is made at step S53 that the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62 has been completely combusted, at step S54 the electrical power to the electrical heater 72 in the PM sensor 62 is stopped.
• step S55 the temperature sensor 73 measures the temperature of the oxidation catalyst 71, and, at step S56, a determination is made as to whether the temperature tpM of the oxidation catalyst 71 measured by the temperature sensor 73 is as low as or lower than the temperature t A at which the exhaust particulate matter cannot be combusted, If the determination is made at this point that the temperature tp M of the oxidation catalyst 71 has decreased to no greater than the temperature t A at which the exhaust particulate matter cannot be combusted, at step S57 accumulation of the intake air amount is started. Then, at step S58, a determination is made of whether the accumulated amount of intake air ⁇ ga is larger than a prescribed value A.
• step S59 a determination is made of whether oxygen is present in the area surrounding the PM sensor 62.
• step S59 when the fuel cut control duration time or accumulation time reaches or exceeds a prescribed time and also the accumulated value of intake air amount reaches or exceeds a prescribed value, the determination is made that the ceria of the oxidation catalyst 71 has occluded a sufficient amount of oxygen, and processing proceeds to step S60.
• step S60 a determination is made of whether the exhaust gas temperature detected by the temperature sensor 73 is at least a prescribed value and also the temperature of the gas flowing in the region of the PM sensor 62 is at least the temperature at which the exhaust particulate matter settled in the oxidation catalyst 71 can be combusted.
• step S61 the accumulated value of intake air amount calculated by the processing of step S57 is canceled, return is made to step S55, and the processing of step S55 and thereafter is performed to again accumulate the intake air amount.
• step S60 if at step S60 the temperature of the exhaust gas passing through the region surrounding the PM sensor 62 detected by the temperature sensor 73 is determined to be not as high as the combustion temperature at which the exhaust particulate matter can be combusted, at step S62 the electrical heater 72 of the PM sensor 62 is electrically powered to heat the oxidation catalyst 71 to combust the exhaust particulate matter settled in the oxidation catalyst 71. Then, at step S63, the sediment amount of exhaust particulate matter is calculated in accordance with the degree of temperature rise of the oxidation catalyst 71 at that time. At step S64, a determination is made of whether the processing to calculate the sediment amount of the exhaust particulate matter has ended, by complete combustion of the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62.
• step S64 if the determination is made that the processing to calculate the sediment amount of the exhaust particulate matter has ended, at step S65 the electrical power to the electrical heater 72 of the PM sensor 62 is stopped, and the ECU 51 ends all processing.
• the exhaust particulate matter measuring apparatus is configured to provide in the exhaust pipe 47 a PM sensor 62 that measures the amount of particulate matter in the exhaust gas, the PM sensor 62 being fixed by stacking the oxidation catalyst 71 and the electrical heater 72 together, and a temperature sensor 73 that measures the temperature of the oxidation catalyst 71 being interposed between the oxidation catalyst 71 and the electrical heater 72.
• the oxidation catalyst 71 carries ceria as an oxygen-storing agent that occludes oxygen in the exhaust gas.
• the ECU 51 heats the oxidation catalyst 71 using the electrical heater 72 and calculates the sediment amount of exhaust particulate matter based on the amount of temperature rise at that time and the accumulated value of the intake air amount.
• the ceria in the oxidation catalyst 71 constantly occludes oxygen present in the exhaust gas.
• the oxidation catalyst 71 is heated by the electrical heater 72, the exhaust particulate matter settled in the oxidation catalyst 71 can be properly combusted with the oxygen occluded in the ceria, and the ECU 51 accurately calculates the sediment amount of exhaust particulate matter, based on the amount of temperature rise at this time and the accumulate value of intake air amount.
• the temperature of the exhaust gas flowing through the region surrounding the oxidation catalyst 71 is at least the combustion temperature at which the exhaust particulate matter can be combusted, the held accumulated value of intake air amount is canceled, and the accumulation of the intake air amount is redone, thereby enabling a proper determination of the sediment amount of exhaust particulate matter with respect to the accumulated value of intake air amount.
• the engine 10 is operating at a stoichiometric air-fuel ratio (theoretical air-fuel ratio)
• oxygen mixed with the exhaust gas is reliably occluded by the ceria of the oxidation catalyst 71 during fuel cut control, for example, it is possible to reliably calculate the sediment amount of the exhaust particulate matter.
• FIG. 10 is a flowchart of the measurement control of the exhaust particulate matter measuring apparatus according to the fourth embodiment of the present invention.
• the overall constitution of the exhaust particulate matter measuring apparatus of the fourth embodiment is substantially the same as that of the first embodiment.
• the fourth embodiment will be described using FIG. 1 and FIG. 2, and members having the same function as those members of embodiments already described are referred to by the same numerals and are not repeatedly described herein.
• the PM sensor 62 that measures the amount of particulate matter in the exhaust gas is provided between the three-way catalyst 49 and the muffler 50 in the exhaust pipe 47.
• the PM sensor 62 as shown in FIG. 2, has an oxidation catalyst 71 and an electrical heater 72, although the oxidation catalyst 71 does not carry ceria.
• the PM sensor 62 can capture particulate matter, and particularly soot particles, in the exhaust gas flowing through the exhaust pipe 47. With exhaust particulate matter captured by the PM sensor 62 and settled up to a prescribed amount and also a sufficient amount of oxygen included in the exhaust gas, when the electrical heater 72 is electrically powered to heat the oxidation catalyst 71, the settled exhaust particulate matter sediment is combusted using the oxygen that is included in the exhaust gas, the ECU 51 calculates the sediment amount of the exhaust particulate matter in accordance with the degree of temperature rise at that time.
• the electrical heater 72 in the PM sensor 62 is electrically powered to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71.
• step S74 the electrical power to the electrical heater 72 in the PM sensor 62 is stopped. Then, at step S75 the temperature sensor 73 measures the temperature of the oxidation catalyst 71, and, at step S76, a determination is made as to whether the temperature tp M of the oxidation catalyst 71 measured by the temperature sensor 73 is as low as or lower than the temperature t A at which the exhaust particulate matter cannot be combusted.
• step S77 accumulation of the intake air amount is started. Then, at step S78, a determination is made of whether the accumulated amount of intake air ⁇ ga is larger than a prescribed value A.
• step S79 a determination is made of whether oxygen is present in the area surrounding the PM sensor 62. In this embodiment, a determination is made as to whether fuel cut control is in progress to estimate whether oxygen is present in the exhaust gas.
• step S79 If execution of fuel cut control is in progress at step S79, the determination is made that sufficient oxygen is present in the area surrounding the oxidation catalyst 71, and processing proceeds to step S80.
• step S80 the electrical heater 72 in the PM sensor
• step S81 the sediment amount of exhaust particulate matter is calculated in accordance with the degree of temperature rise of the oxidation catalyst 71 at this time.
• step S82 a determination is made of whether the processing to calculate the sediment amount of the exhaust particulate matter has ended, by complete combustion of the exhaust particulate matter settled in the oxidation catalyst 71 of the PM sensor 62.
• step S82 if the determination is made that the processing to calculate the sediment amount of the exhaust particulate matter has ended, at step S83 the electrical power to the electrical heater 72 of the PM sensor 62 is stopped, and the ECU 51 ends all processing.
• the exhaust particulate matter measuring apparatus is configured to provide in the exhaust pipe 47 the PM sensor 62 that measures the amount of particulate matter in the exhaust gas, the PM sensor 62 being fixed by stacking the oxidation catalyst 71 and the electrical heater 72 together, and a temperature sensor 73 that measures the temperature of the oxidation catalyst 71 being interposed between the oxidation catalyst 71 and the electrical heater 72.
• the ECU 51 heats the oxidation catalyst 71 using the electrical heater 72 and calculates the sediment amount of exhaust particulate matter based on the amount of temperature rise at that time and the accumulated value of the intake air amount.
• the exhaust gas is lean and sufficient oxygen is present in the exhaust gas.
• the oxidation catalyst 71 is heated by the electrical heater 72, the exhaust particulate matter captured by the oxidation catalyst 71 can be properly combusted along with the oxygen in the exhaust gas, and the ECU 51 accurately calculates the sediment amount of exhaust particulate matter, based on the amount of temperature rise at this time and the accumulate value of intake air amount.
• FIG. 11 is a flowchart of the measurement control of the exhaust particulate matter measuring apparatus according to the fifth embodiment of the present invention.
• the overall constitution of the exhaust particulate matter measuring apparatus of the fifth embodiment is substantially the same as that of the first embodiment.
• the fifth embodiment will be described using FIG. 1 and FIG. 2, and members having the same function as those members of embodiments already described are referred to by the same numerals and are not repeatedly described herein.
• the PM sensor 62 that measures the amount of particulate matter in the exhaust gas is provided between the three-way catalyst 49 and the muffler 50 in the exhaust pipe 47.
• the PM sensor 62 as shown in FIG. 2, has an oxidation catalyst 71, an electrical heater 72, and a temperature sensor 73. Therefore, the PM sensor 62 can capture particulate matter, and particularly soot particles, in the exhaust gas flowing through the exhaust pipe 47.
• the ECU 51 calculates the sediment amount of the exhaust particulate matter in accordance with the degree of temperature rise at that time. According to this embodiment, the rich operation of the engine 10 is prohibited during calculation of the sediment amount of exhaust particulate matter.
• the electrical heater 72 in the PM sensor 62 is electrically powered to heat the oxidation catalyst 71, thereby combusting the exhaust particulate matter settled in the oxidation catalyst 71.
• step S94 the electrical power to the electrical heater 72 in the PM sensor 62 is stopped. Then, at step S95 the temperature sensor 73 measures the temperature of the oxidation catalyst 71, and, at step S96, a determination is made as to whether the temperature tp ⁇ of the oxidation catalyst 71 measured by the temperature sensor 73 is as low as or lower than the temperature t A at which the exhaust particulate matter cannot be combusted.
• step S97 accumulation of the intake air amount is started. Then, at step S98, a determination is made of whether the accumulated amount of intake air ⁇ ga is larger than a prescribed value A.
• step S99 a determination is made of whether oxygen is present in the area surrounding the PM sensor 62.
• a determination may be made of whether the ceria of the oxidation catalyst 71 has occluded a sufficient amount of oxygen, based on the fuel cut control duration time or accumulation time, similar to the cases of the first and third embodiments already described.
• step S99 If the determination is made at step S99 that sufficient oxygen is present in the area surrounding the oxidation catalyst 71, processing proceeds to step SlOO, at which point the ECU 51 prohibits rich operation of the engine 10. That is, when the PM sensor 62 calculates the sediment amount of exhaust particulate matter, if the engine 10 is operated in the rich condition and the exhaust gas is a rich atmosphere, the oxygen present in the area surrounding the oxidation catalyst 71 is consumed in the oxidation of the rich exhaust gas, thereby reducing the amount of oxygen for combustion of the exhaust particulate matter settled in the oxidation catalyst 71.
• the exhaust particulate matter settled in the oxidation catalyst 71 is combusted by electrically powering the electrical heater 72 in the PM sensor 62 to heat the oxidation catalyst 71 at step SlOl.
• the sediment amount of the exhaust particulate matter is calculated in accordance with the degree of temperature rise of the oxidation catalyst 71 at that time.
• the sediment amount of exhaust particulate matter is calculated based on the temperature change at that time, the prohibition of rich operation of the engine 10 makes it possible to reliably combust the exhaust particulate matter using the oxygen present in the area surrounding the oxidation catalyst 71, and to properly calculate the sediment amount of the exhaust particulate matter.
• step S 104 electrical power to the electrical heater 72 in the PM sensor 62 is stopped and, at step S 105, the prohibition of rich operation of the engine 10 is removed, the ECU 51 ends the process.
• the exhaust particulate matter measuring apparatus is configured to provide in the exhaust pipe 47 a PM sensor 62 that measures the amount of particulate matter in the exhaust gas, the PM sensor 62 is fixed by stacking the oxidation catalyst 71 and the electrical heater 72 together, and a temperature sensor 73 that measures the temperature of the oxidation catalyst 71 being interposed between the oxidation catalyst 71 and the electrical heater 72.
• the ECU 51 prohibits rich operation of the engine 10, after which it heats the oxidation catalyst 71 using the electrical heater 72 and calculates the sediment amount of exhaust particulate matter based on the amount of temperature rise at that time and the accumulated value of the intake air amount.
• the ECU 51 may prohibit rich operation of the engine 10 when sufficient oxygen is present in the area surrounding the oxidation catalyst 71, by heating the oxidation catalyst 71 using the electrical heater 72 without consuming the oxygen present in the area surrounding the oxidation catalyst 71 in the oxidation of exhaust particulate matter of the rich exhaust gas, exhaust particulate matter captured by the oxidation catalyst 71 is properly combusted along with the oxygen present in the area surrounding the oxidation catalyst 71, and the ECU 51 accurately calculates the sediment amount of exhaust particulate matter, based on the amount of temperature rise at that time and the accumulated value of intake air amount.
• ceria is carried by the oxidation catalyst 71, even if the engine 10 is operated at a stoichiometric air-fuel ratio (theoretical air-fuel ratio), because the ceria of the oxidation catalyst 71 reliably occludes the oxygen mixed in the exhaust gas during, for example, execution of the fuel cut control, it is possible to reliably calculate the sediment amount of exhaust particulate matter.
• the exhaust particulate matter settled in the oxidation catalyst 71 is combusted by the PM sensor 62 disposed in the exhaust pipe 47 in the internal combustion engine 10 and the discharged amount of the exhaust particulate matter in the exhaust gas is estimated based on the temperature change of the oxidation catalyst 71, and the engine 10 may be controlled to change the fuel injection amount or air-fuel ratio to reduce the discharged amount, based on the estimated amount of discharge of the exhaust particulate matter.
• the exhaust particulate matter measuring apparatus accurately measures the amount of exhaust particulate matter in the exhaust gas based on the temperature change, and may be applied to any type of internal combustion engine.
• the above-described first and third embodiments use ceria as an oxygen-storing agent in the oxidation catalyst 71, the present invention is not restricted to these embodiments, and is compatible with oxygen-storing agents other than ceria.

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