Isuzu Motors Limited

Naoto Murasawa

Tadashi Uchiyama

Satoshi Hanawa

Hidekazu Fujie

Teruo Nakada

Kazuo Oosumi

Masahiro Kajiyama

Takayuki Mukunashi

Akio Nishikata

Provided are an exhaust purification device and an exhaust purification method which can achieve improved fuel efficiency. The exhaust purification device () is equipped with: a DOC () for occluding hydrocarbons in an exhaust gas; a DPF () that is provided downstream from the DOC () and is for trapping particulate matter in the exhaust gas; and an ECU () for determining, in accordance with the amount of occluded hydrocarbons in the DOC (), a start time for a regeneration process for removing particulate matter accumulated in the DPF ().

Exhaust purification device and exhaust purification method

The PM sensor includes: a filter member having a plurality of measuring cells which are defined by a porous partition wall and configured to trap particulate matter in exhaust gas; at least a pair of electrode members which are disposed to face each other with the measuring cell sandwiched therebetween to form a condenser; a heater member which heats the measuring cell to burn and remove particulate matter accumulated in the measuring cell; and an estimation unit which estimates an amount of the particulate matter contained in the exhaust gas based on an electrostatic capacity between the pair of electrode members.

Sensor

The sensor includes a filter member including cells that trap PM in exhaust gas, electrode members arranged to face each other with the cell interposed and forming a capacitor, an electric heater that executes, when an amount of PM has accumulated in the cells, filter regeneration for combusting and removing the PM, a temperature sensor that acquires the temperature of the filter member, a storage unit that stores therein a reference temperature, which is the temperature of the filter member where the filter regeneration has been executed in a state in which PM is not flowing into the filter member, and estimation units that estimate a PM amount included in the exhaust gas based on (a) an electrostatic capacitance change amount between the electrode members during a regeneration interval and (b) a difference between the temperature acquired by the temperature sensor and the reference temperature during a filter regeneration interval.

Particulate matter (PM) sensor

The sensor includes a filter member including cells that trap PM in exhaust gas; electrode members arranged to face each other with the cell interposed and forming a capacitor, an electric heater that executes, when an amount of PM has accumulated in the cells, filter regeneration of heating the cells to combust and remove the PM, a storage unit that stores a reference reduction amount, which is an electrostatic capacitance reduction amount between the electrode members in a case where the filter regeneration is executed in a state where the PM is not flowing into the filter member, and estimation units that estimate a PM amount based on (a) an actual electrostatic capacitance change amount between the electrode members during a regeneration interval period, and (b) a difference between an actual electrostatic capacitance reduction amount between the electrode members and the reference reduction amount during a filter regeneration period.

An exhaust purification system includes: a diesel oxidation catalyst (DOC) provided on an exhaust path of an engine; an upstream diesel particulate filter (DPF) and a downstream DPF that are provided on the exhaust path at positions downstream of the DOC to collect particulate matter contained in exhaust gas; electrodes that detect a capacitance of the upstream DPF; a particulate matter accumulation estimating unit that estimates at least an amount of particulate matter accumulated in the downstream DPF on the basis of the capacitance received from the electrodes; and a forced regeneration control unit that injects fuels into the DOC and performs forced regeneration that burns and removes at least the particulate matter accumulated in the downstream DPF when the estimated amount of particulate matter from the particulate matter accumulation estimating unit surpasses a predetermined amount.

Exhaust purification system

A diagnosis device includes: a diesel particulate filter (DPF) collecting particulate matter (PM) in exhaust gas; a resistive type PM sensor provided downstream of the DPF, detecting an amount of PM from current flowing through PM deposited between electrodes. An actual regeneration interval calculator calculating an actual interval from completion of regeneration of the sensor to a start of the next regeneration; a PM slippage amount calculator estimating an amount of PM slippage in exhaust gas that slips through the DPF, assuming the DPF is normal; an estimated regeneration interval calculator calculating, on the basis of the PM slippage amount, an estimated interval from completion of the regeneration of the sensor to the start of the next regeneration; and a DPF failure-normal determination device determining whether the DPF has failed or is normal by comparing the actual interval to the estimated interval.

Diagnosis device

A diagnostic device includes: a diesel oxidation catalyst (DOC) for oxidizing hydrocarbon (HC) and nitrogen monoxide in an exhaust gas; a selective catalytic reduction (SCR) catalyst for reducing and purifying NOx contained in the exhaust gas; a NOx purification rate calculation unit which calculates, based on NOx values at upstream and downstream sides of the SCR catalyst, a low temperature NOx purification rate and a high temperature NOx purification rate; a HC heat generation rate calculation unit which calculates an HC purification rate based on at least the difference between the exhaust gas heat quantities at upstream and downstream sides of the DOC; and a deterioration determination unit which determines the deterioration in the NOproducing capability of the DOC based on the calculated low temperature NOx purification rate, the calculated high temperature NOx purification rate, and the calculated HC purification rate.

Diagnostic device for an oxidation catalyst

A diagnosis device diagnoses a cooler adapted to cool a fluid flowing through intake and exhaust systems of an engine, and includes: a downstream temperature sensor for detecting a fluid temperature downstream of the cooler; a fluid temperature calculation unit for calculating a fluid temperature upstream of the cooler based on a fluid state quantity; a sensor output value calculation unit for assuming an upstream temperature sensor configured to detect a fluid temperature upstream of the cooler, reflecting a sensor response delay in the calculated fluid temperature, and calculating an estimated sensor output value of the upstream temperature sensor; and a cooler diagnosis unit for diagnosing the cooling efficiency of the cooler based on an actual sensor input value entered from the downstream temperature sensor and the calculated estimated sensor output value.

An exhaust purification system includes: a diesel oxidation catalyst (DOC) provided on an exhaust passage of an engine; a diesel particulate filter (DPF) provided on the exhaust passage at a position downstream of the DOC to collect particulate matter contained in exhaust gas; electrodes that detect a capacitance of the DOC; a particulate matter accumulation estimating unit that estimates an amount of particulate matter accumulated in the DPF on the basis of the detected capacitance; and a forced regeneration control unit that injects fuel into the DOC and performs forced regeneration that burns and removes at least the particulate matter accumulated in the DPF when the estimated accumulated particulate matter amount surpasses a predetermined amount.

A diagnostic device includes: a DOC for oxidizing hydrocarbon (HC) contained in an exhaust gas; a first sensor for detecting an exhaust gas temperature at a DOC inlet; a second sensor for detecting an exhaust gas temperature at a DOC outlet; a third sensor for detecting ambient temperature; an HC heat generation rate calculation unit which calculates, based on detection values of the first and second sensors, a difference in an exhaust gas heat quantity between upstream and downstream sides of the DOC, calculates, based on the detection values of the three sensors, a heat loss quantity released to outside air from the DOC, and adds the heat loss quantity and the exhaust gas heat quantity difference to calculate a heat generation quantity of HC in the DOC; and a DOC deterioration determination unit which determines, based on the calculated HC heat generation quantity, deterioration of the DOC.

Diagnostic device

A diagnostic device for an exhaust gas purification system that has a diesel oxidation catalyst (DOC), a diesel particulate filter, and an exhaust pipe injection device. The device includes a sensor for detecting a temperature of the DOC, a first calculation unit for converting an integration time of the detected temperature between regeneration intervals into a thermal history time with respect to a predetermined set temperature, and calculating a degree of degradation of the DOC based on this thermal history time, a second calculation unit for calculating a quantity of heat generated in the DOC based on the detected temperature during a forced regeneration execution period, and calculating another degree of degradation of the DOC based on the quantity of heat generated; and a diagnosis unit for diagnosing a degradation state of the DOC based on the degrees of degradation entered from the first and second calculation units.

An exhaust purification system includes a selective catalytic reduction (SCR) catalyst disposed at an exhaust system of an engine for using ammonia that is generated from urea water as a reducing agent to reduce NOx contained in exhaust gas, a device that injects urea water to the SCR catalyst, an inlet-side electrode that detects capacitance within the SCR catalyst at least from a vicinity of an inlet of the SCR catalyst to a vicinity of an intermediate section in an exhaust gas flowing direction, an outlet-side electrode that detects the capacitance within the SCR catalyst at least from the vicinity of the intermediate section to an outlet of the SCR catalyst in the exhaust gas flowing direction, and a calculation unit that calculates an ammonia adsorption amount within the SCR catalyst on a basis of the capacitances detected from the inlet-side and the outlet-side electrodes.

Growing community of inventors

Yamato, Japan

Naoto Murasawa