JP6568372B2 - Exhaust purification equipment - Google Patents

Description

  The present invention relates to an exhaust gas purification apparatus that purifies exhaust gas such as diesel engine by post-processing, and particularly relates to an apparatus that suppresses dilution of engine oil during regeneration of a particulate matter filter.

For example, a diesel engine for automobiles is provided with a diesel particulate filter (DPF) that filters and collects particulate matter (PM) such as soot (soot) contained in exhaust gas by a filter made of, for example, ceramic. ing.
In such a DPF, if the amount of accumulated PM increases with the passage of operating time, clogging occurs and adversely affects the operability of the engine. Therefore, when the amount of accumulated PM increases, it is burned and incinerated. The regeneration operation to process is performed.

The regeneration operation is performed by burning PM at a high temperature in the DPF layer. The temperature rise and temperature maintenance in the DPF layer for stably burning soot is performed by, for example, performing post injection that injects fuel in the exhaust stroke from the late stage of the engine expansion stroke, and supplying unburned fuel in the exhaust Is done by.
The unburned fuel is oxidized (combusted) in an oxidation catalyst (DOC) provided on the upstream side of the DPF, and the exhaust temperature serving as a feed gas to the DPF is raised.
The DPF is heated to a temperature required for PM ignition and combustion maintenance by the flow of exhaust gas heated by the DOC, and the temperature is maintained until the end of the regeneration operation.

As a conventional technique related to DPF regeneration, for example, in Patent Document 1, when the amount of accumulated PM exceeds a level that affects drivability, DPF regeneration is executed regardless of the operation state, and the accumulated amount of PM becomes drivable. It is described that DPF regeneration is executed when the level is such that PM can be propagated and burned and the engine operating state is suitable for DPF regeneration even if the level is not affected.
Patent Document 2 describes that DPF regeneration is executed only when the operating conditions with good temperature rise efficiency are obtained when the amount of collected PM is between the first and second threshold values.
Patent Document 3 describes that when the filter temperature is equal to or higher than a predetermined temperature, the regeneration operation is started even when the amount of particulates in the filter is relatively small.
In Patent Document 4, regeneration is executed when the PM amount of the filter is equal to or greater than a threshold value, and the threshold value is set to a small value in a load region where regeneration is possible without supplying unburned fuel in the exhaust gas. It is described to set to.
In Patent Document 5, when the collection amount of exhaust particulates is equal to or greater than a first reference value, regeneration is performed only when the engine load is high, and the collected amount is equal to or greater than a second reference value greater than the first reference value. In this case, it is described that the reproduction is performed regardless of the load state.

JP 2003-293824 A JP 2004-019496 A JP-A-5-296027 JP 2006-316731 A JP 2005-90458 A

As described in the prior art, it is well known to perform DPF regeneration when the engine is operating at a relatively high load.
However, for example, when attention is paid to specific parameters such as engine load and exhaust temperature, there is a case where DPF regeneration cannot actually be performed properly even if it is easily determined that the operation state is suitable for DPF regeneration.
For example, even when the engine is in a high load state, if the exhaust gas flow rate is excessively large, the exhaust catalyst cools the oxidation catalyst and the DPF, making it difficult to raise the temperature and maintain the temperature of the DPF. In-layer temperature controllability may deteriorate.
On the other hand, even when the exhaust gas flow rate is excessively small, overheating of the DPF and an increase in time constant (delay in time response of the temperature inside the layer with respect to changes in the engine operating state) become problems and the temperature controllability deteriorates.

When regeneration operation is performed under such conditions that are not suitable for regeneration of DPF, it is necessary to increase the post injection amount in order to stably burn PM.
When the post-injection amount is increased, a part of the fuel adheres to the cylinder wall surface and is scraped off together with the oil by the oil ring of the piston to dilute the oil.
In order to suppress the dilution of the oil, it is necessary to efficiently perform the DPF regeneration with the smallest possible post injection amount.
In view of the above-described problems, an object of the present invention is to provide an exhaust emission control device that suppresses dilution of engine oil during regeneration of a particulate matter filter.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided an oxidation catalyst and a particulate matter filter that are sequentially arranged from an upstream side in an exhaust pipe of an engine, and a post-injection by the fuel injection device of the engine, whereby the particulate matter filter An exhaust emission control device comprising a regeneration suitability judging means for judging the suitability of a regeneration operation for performing regeneration, a load detecting means for judging a load state of the engine , a climbing judgment means for judging a climbing state of a vehicle, An exhaust flow rate detecting means for detecting an exhaust flow rate of the engine, wherein the regeneration suitability determining means determines the predetermined high load condition by the load detecting means , the climbing slope determining means determines the climbing state, and An exhaust emission control device that determines that the exhaust flow rate is suitable for the regeneration operation when the exhaust gas flow rate is within a range between a predetermined upper threshold value and a lower threshold value. .
According to a second aspect of the present invention, there is provided an oxidation catalyst and a particulate matter filter that are sequentially arranged from an upstream side in an exhaust pipe of an engine, and a post-injection performed by the fuel injection device of the engine, whereby the particulate matter filter An exhaust emission control device comprising regeneration appropriateness determining means for determining the appropriateness of regeneration operation for performing regeneration, load detecting means for determining the load state of the engine, and high speed traveling determining means for determining a high speed traveling state of the vehicle, And an exhaust flow rate detecting means for detecting an exhaust flow rate of the engine, wherein the regeneration suitability determining means determines the predetermined high load condition by the load detecting means, and the high speed traveling determining means determines the high speed traveling state. And when the exhaust flow rate is within a range between a predetermined upper limit side threshold value and a lower limit side threshold value, it is determined that the state is suitable for the regeneration operation. It is a gas purifying device.
According to these respective inventions, by determining the exhaust flow rate as a state suitable for regeneration operation when a range between a predetermined upper limit threshold and the lower-side threshold, the exhaust flow rate is excessive or Since it is too small, the temperature controllability in the particulate matter filter layer during regeneration can be prevented from being deteriorated, and the particulate matter filter can be efficiently regenerated with a small amount of post injection.
Thereby, mixing of the fuel into the oil can be suppressed, and dilution of the oil can be prevented.

The invention according to claim 3 includes an oxygen concentration detection means for detecting an oxygen concentration in the exhaust gas upstream of the oxidation catalyst, and the regeneration suitability determination means is configured to perform the regeneration operation when the oxygen concentration is equal to or higher than a predetermined value. The exhaust emission control device according to claim 1 , wherein the exhaust gas purification device is determined to be in a state suitable for the exhaust gas.
According to this, when it is determined that the state is suitable for the regeneration operation when the oxygen concentration is equal to or higher than a predetermined value, oxygen necessary for oxidation of unburned fuel in the oxidation catalyst and oxidation of soot in the particulate matter filter is increased. Regeneration operation is started in a deficient or deficient state, and post injection that does not substantially contribute to regeneration of the particulate matter filter can be prevented from being performed wastefully.

The invention according to claim 4 includes exhaust temperature detection means for detecting the exhaust temperature, and the regeneration suitability determination means determines that the state is suitable for the regeneration operation when the exhaust temperature is equal to or higher than a predetermined value. The exhaust emission control device according to any one of claims 1 to 3, wherein:
According to this, when the exhaust gas temperature is high, it is determined that the state is suitable for the regeneration operation, so that the post-injected fuel is reliably burned in the oxidation catalyst to raise the exhaust gas temperature, and the particulate matter The filter can be reliably regenerated.

According to a fifth aspect of the present invention, there is provided a regeneration operation executing means for executing the regeneration operation when a frequency at which the regeneration suitability determining means determines that the regeneration appropriate state is suitable for the regeneration operation is a predetermined value or more within a predetermined period. The exhaust emission control device according to any one of claims 1 to 4 , wherein the exhaust purification device is provided.
According to this, when the frequency determined to be suitable for the regeneration operation is high, the regeneration operation is executed, for example, when the regeneration is started at the time of temporary sudden acceleration or the like. Therefore, it is possible to prevent the regeneration efficiency from deteriorating and to effectively perform the regeneration operation.

  As described above, according to the present invention, it is possible to provide an exhaust emission control device that suppresses dilution of engine oil during regeneration of a particulate matter filter.

It is a figure which shows the structure of the diesel engine which has the Example of the exhaust gas purification apparatus to which this invention is applied. It is a flowchart which shows the regeneration driving | operation appropriateness determination in the exhaust gas purification apparatus of an Example.

  The present invention satisfies the problem of providing an exhaust purification device that suppresses dilution of engine oil during regeneration of a particulate matter filter, and satisfies various conditions such as a high engine load and an exhaust flow rate within a predetermined range. In such a case, the reproduction suitability determination is established, and the necessity of reproduction is determined according to the establishment frequency.

Embodiments of an exhaust emission control device to which the present invention is applied will be described below.
FIG. 1 is a schematic diagram illustrating a configuration of a diesel engine having an exhaust purification device of an embodiment.
The engine 10 includes a turbocharger 20, an intake system 30, an exhaust system 40, a fuel supply device 50, an EGR device 60, an oxidation catalyst (DOC) 70, a diesel particulate filter (DPF) 80, an engine control unit (ECU) 100, and the like. It is prepared for.

The engine 10 is, for example, a four-stroke diesel engine used as a driving power source for automobiles such as passenger cars.
The engine 10 includes a crankshaft 11, a piston 12, a cylinder block 13, a head 14, a combustion chamber 15, a glow plug 16, a glow controller 17, and the like.

The crankshaft 11 is an output shaft of the engine 10.
The piston 12 is a member that reciprocates in the cylinder and transmits the combustion pressure to the crankshaft 11 via the connecting rod.
The cylinder block 13 is formed integrally with a cylinder portion in which the piston 12 is accommodated and a crankcase portion in which the crankshaft 11 is rotatably supported.
The cylinder block 13 includes a crank angle sensor 13a and a water temperature sensor 13b.
The crank angle sensor 13a detects the angular position of the crankshaft 11.
The water temperature sensor 13 b detects the cooling water temperature circulating in the water jacket in the engine 10.
The head 14 is provided at the crown-side end of the piston 12 of the cylinder block 13 and includes an intake port, an exhaust port, a valve drive mechanism that opens and closes the intake valve and the exhaust valve, and the like.
The combustion chamber 15 is formed between the crown surface of the piston 12 and the portion of the head 14 facing this.
The glow plug 16 is a preheating device provided in the head 14 with the tip portion exposed in the combustion chamber 15.
The glow controller 17 controls the energization amount to the glow plug 16 according to the control of the ECU 100.

The turbocharger 20 compresses combustion air (fresh air) taken in by the engine 10 using energy of exhaust (burned gas) of the engine 10.
The turbocharger 20 includes a compressor 21, a turbine 22, an actuator 23, a negative pressure control valve 24, and the like.

The compressor 21 is a centrifugal compressor that compresses combustion air.
The turbine 22 is provided coaxially with the compressor 21 and is driven by the exhaust of the engine 10 and drives the compressor 21. The turbine 22 is of a variable geometry type in which the geometry can be continuously changed by a movable vane provided in nozzles around the turbine wheel.
The actuator 23 is a negative pressure type actuator that drives a movable vane of the turbine 22.
The negative pressure control valve 24 is an electromagnetic valve that introduces a negative pressure from a negative pressure source (not shown) into the actuator 23 according to the control of the ECU 100.
When the actual supercharging pressure is lower than the target supercharging pressure set by the ECU 100, the turbocharger 20 increases the rotational speed of the turbine 22 by closing the movable vane and narrowing the nozzle, Control to increase the pressure is performed.

The intake system 30 introduces combustion air into the engine 10.
The intake system 30 includes an intake duct 31, an air cleaner 32, an air flow meter 33, an intercooler 34, a throttle valve 35, an actuator 36, an intake chamber 37, an intake pressure sensor 38, an intake manifold 39, and the like.

The intake duct 31 is an air flow path that introduces combustion air from the atmosphere and supplies it to the engine 10 via the compressor 21 of the turbocharger 20.
The air cleaner 32 includes a filter element that filters air to remove dust and the like. The air that has passed through the air cleaner 32 is introduced into the compressor 21 of the turbocharger 20 and compressed.
The air flow meter 33 is provided at the outlet of the air cleaner 32 and includes a sensor that detects the air flow rate. The air flow meter 33 includes an intake air temperature sensor for detecting the intake air temperature.

The intercooler 34 is a heat exchanger that cools the air that has exited the compressor 21 of the turbocharger 20 by heat exchange with the traveling wind.
The throttle valve 35 is provided on the downstream side of the intercooler 34 and adjusts the intake air amount of the engine 10.
The actuator 36 opens and closes the throttle valve 35 in response to a control signal from the ECU 100.
The intake chamber 37 is an air chamber into which air that has passed through the throttle valve 35 is introduced, and is connected to an intake port of the engine 10 via an intake manifold 39.
The intake pressure sensor 38 is provided in the intake chamber 37 and detects a pressure in the intake chamber 37 substantially equal to the intake pressure of the engine 10.
The intake manifold 39 is a branch pipe that introduces air from the intake chamber 37 to the intake port of each cylinder of the engine 10.

The exhaust system 40 includes an exhaust manifold 41, an exhaust pipe 42, and the like.
The exhaust manifold 41 is a pipe line that collects exhaust gas discharged from the exhaust ports of the cylinders of the engine 10 and introduces the exhaust gas into the turbine 22 of the turbocharger 20.
The exhaust pipe 42 is a pipe line that discharges the exhaust discharged from the turbine 22 to the outside of the vehicle. The exhaust pipe 42 is provided with an exhaust purification device (exhaust gas aftertreatment device) such as a DOC 70 and a DPF 80.

  The fuel supply device 50 supplies fuel into the combustion chamber 15 of the engine 10. The fuel supply device 50 is a common rail type high pressure fuel injection device including a supply pump 51, a suction metering solenoid valve 52, a fuel temperature sensor 53, a common rail 54, a fuel pressure sensor 55, an injector 56, and the like.

The supply pump 51 includes, for example, an inner cam type pressure feeding system, and pressurizes light oil as fuel and supplies it to the common rail 54.
The intake metering solenoid valve 52 adjusts the fuel intake amount of the supply pump 51 and is driven according to a control signal from the ECU 100.
The fuel temperature sensor 53 detects the temperature of the fuel in the supply pump 51.

The common rail 54 is a pressure accumulator that stores high-pressure fuel discharged from the supply pump 51.
The fuel pressure sensor 55 detects the fuel pressure (fuel pressure) in the common rail 54. The above-mentioned intake metering solenoid valve 52 is adjusted in its opening degree by feedback control using the output of the fuel pressure sensor 55 so that the fuel pressure becomes a predetermined target value set according to, for example, the engine speed and load. The
The injector 56 is a fuel injection device that injects fuel supplied from the common rail 54 into the combustion chamber 15 of each cylinder. The injector 56 has a valve body that is opened and closed by an actuator such as a piezo element or a solenoid, and is opened in response to an injection pulse signal from the ECU 100. The injection timing and injection amount of the injector 56 are controlled by the ECU 100.
The injector 56 performs main injection, pilot injection for injecting a small amount of fuel prior to the main injection, post injection for injecting a small amount of fuel after the main injection, and the like.

The EGR device 60 is intended to recirculate a part of the exhaust of the engine 10 extracted from the exhaust pipe 42 into the intake duct 31 for the purpose of reducing the NOx emission amount by suppressing the combustion temperature.
The EGR device 60 includes an EGR passage 61, an EGR control valve 62, an EGR cooler 63, and the like.
The EGR passage 61 is a pipe line that extracts exhaust gas from a region on the outlet side of the DPF 80 in the exhaust pipe 42 and introduces the exhaust gas into an intermediate portion of the intake duct 31 between the air flow meter 33 and the compressor 21 of the turbocharger 20.
The EGR control valve 62 adjusts the exhaust gas flow rate (EGR amount) of the EGR passage 61 according to the control of the ECU 100.
The EGR cooler 63 cools the exhaust gas flowing through the EGR passage 61 by exchanging heat with the traveling wind.

The DOC 70 is provided in the exhaust pipe 42 and mainly oxidizes hydrocarbons (HC) in the exhaust. The DOC 70 is formed by supporting a noble metal such as platinum or palladium or a metal oxide such as alumina on the surface of a ceramic carrier such as a cordierite honeycomb structure.
The DOC 70 is provided with a temperature sensor 71 for detecting the exhaust temperature at the inlet portion.
During the regeneration operation of the DPF 80, the DOC 70 has a function of raising the temperature of the exhaust gas by oxidizing (combusting) the fuel that is post-injected and mixed in the exhaust gas in an unburned state.

The DPF 80 is provided on the downstream side of the DOC 70 of the exhaust pipe 42 and includes a filter that collects particulate matter (PM) by filtering the exhaust gas. Here, PM includes soot (soot), organic solvent soluble components (SOF), sulfate (SO ₄ ), and the like.
For example, the filter is formed by forming heat resistant ceramics such as cordierite in a honeycomb structure, and sealing a large number of cells serving as gas flow paths at the end face so that the inlet side and the outlet side are staggered. It is a closed type (wall flow type).
The DPF 80 includes a differential pressure sensor 81 that detects a differential pressure between the inlet pressure and the outlet pressure, and a temperature sensor 82 that detects the exhaust temperature of the outlet.

The ECU 100 controls the above-described engine 10 and its auxiliary devices in an integrated manner, and includes an information processing device such as a CPU, a storage device such as a ROM and a RAM, an input / output interface, an A / D converter, Peripheral circuits such as timers, counters and various logic circuits are provided.
In addition to the various sensors described above, the output of the accelerator pedal sensor 101, the atmospheric pressure sensor 102, and the A / F sensor 103 is input to the ECU 100.
The accelerator pedal sensor 101 is request torque detection means for detecting driver request torque by detecting the position of the accelerator pedal operated by the driver.
The atmospheric pressure sensor 102 detects atmospheric pressure in the ambient atmosphere of the vehicle.
The A / F sensor 103 is provided upstream of the DOC 70 in the exhaust pipe 40 and detects the oxygen concentration in the exhaust gas.

  The ECU 100 sets the target torque of the engine 10 according to the required torque set according to the output of the accelerator pedal sensor 101, and based on this, the opening of the throttle valve 35, the fuel injection amount of the fuel supply device 50, and Control timing, fuel pressure, etc.

The ECU 100 has PM accumulation amount estimation means for estimating the PM accumulation amount of the DPF 80 based on the detection value of the differential pressure sensor 81 and the like.
The ECU 100 supplies the unburned fuel into the exhaust by performing post-injection of the fuel in the later stage of the expansion stroke or in the exhaust stroke when the estimated PM accumulation amount is equal to or greater than a first threshold value set in advance. The unburned fuel is oxidized (combusted) in the DOC 70 to raise the exhaust temperature, and a regeneration operation is performed in which PM accumulated in the DPF 80 is subjected to combustion treatment.
The first threshold is set in consideration of the upper limit value of the PM accumulation amount that does not cause an extreme adverse effect on the operability of the engine 10.

In addition, when the estimated amount of accumulated PM is equal to or larger than a second threshold value that is smaller than the first threshold value, the ECU 100 determines that the current driving state is suitable for regeneration of the DPF based on the running conditions of the engine and the vehicle. It is determined whether or not the state (a state advantageous for regeneration / a state where DPF regeneration is possible with a small amount of post-injection) and the frequency of becoming a state suitable for regeneration of the DPF is a predetermined value or more, A function of determining the start of the DPF regeneration operation is provided even when the PM accumulation amount is less than the first threshold.
The second threshold value is set in consideration of the lower limit value of the PM accumulation amount capable of burning PM by post injection.
FIG. 2 is a flowchart showing determination of whether or not the regeneration operation is appropriate in the exhaust purification apparatus of the embodiment. The process shown in FIG. 2 is executed when the PM accumulation amount is in an intermediate region between the first threshold value and the second threshold value.
Hereinafter, the steps will be described step by step.

<Step S01: High load area determination>
The ECU 100 determines whether or not the operating state of the engine 10 is in a predetermined high load region based on the current rotational speed of the engine 10 (rotational speed of the crankshaft 11), fuel injection amount, and the like.
For example, when the rotational speed of the engine 10 is equal to or greater than a predetermined threshold and the fuel injection amount per cylinder and one cylinder is equal to or greater than the predetermined threshold, the high load region determination is established.
When the high load area determination is established, the process proceeds to step S02, and when it is not established, the process proceeds to step S09.

<Step S02: Climbing judgment>
The ECU 100 determines whether or not the vehicle is currently climbing up in a mountainous area.
For example, when the atmospheric pressure detected by the atmospheric pressure sensor 102 is equal to or lower than a predetermined threshold (high altitude) and the vehicle speed is equal to or higher than the predetermined threshold, the uphill determination is established.
When the uphill determination is established, the process proceeds to step S04, and when it is not established, the process proceeds to step S03.

<Step S03: High-speed running determination is established>
The ECU 100 determines whether or not the host vehicle is currently traveling at a high speed.
For example, when the vehicle speed detected by a vehicle speed sensor (not shown) is equal to or higher than a predetermined threshold, the high speed traveling determination is established.
If the high speed running determination is established, the process proceeds to step S04, and if not, the process proceeds to step S09.

<Step S04: Exhaust Flow Determination>
The ECU 100 determines whether or not the exhaust volume flow rate (exhaust flow rate) estimated from the operating state of the engine 10 is within a range between a preset lower limit side threshold value and an upper limit side threshold value.
The exhaust flow rate is estimated from, for example, the intake air amount of the engine 10, the rotational speed, the combustion injection amount, and the like.
The upper limit side threshold value is set in consideration of the upper limit value of the exhaust gas flow rate at which the DPF 80 is cooled by the exhaust gas and the temperature controllability of the DPF 80 at the time of regeneration is not deteriorated.
The lower limit side threshold value is the lower limit value of the exhaust flow rate in which overheating of the DPF 80 occurs and the time response delay of the temperature of the DPF 80 with respect to changes in the operating state of the engine 10 also increases, and the temperature controllability of the DPF 80 during regeneration does not deteriorate It is set in consideration of.
When the exhaust gas flow rate is within the range between the lower limit side threshold value and the upper limit side threshold value, the process proceeds to step S05, and in other cases, the process proceeds to step S09.

<Step S05: Exhaust temperature judgment>
The ECU 100 determines whether or not the exhaust gas temperature detected by the temperature sensor 71 is equal to or higher than a predetermined threshold value set in advance.
The threshold value is set in consideration that the fuel that has been post-injected in the DOC 70 is surely burned.
If the exhaust temperature is equal to or higher than the threshold value, the process proceeds to step S06, and otherwise, the process proceeds to step S09.

<Step S06: Determination of acceleration>
ECU 100 determines whether or not the longitudinal acceleration of the vehicle calculated based on the change in the detection value of the vehicle speed sensor is equal to or less than a predetermined threshold value set in advance.
The threshold value is set in consideration of the fact that it is possible to discriminate this when the vehicle performs a temporary or short-term rapid acceleration.
If the acceleration is equal to or less than the threshold value, the process proceeds to step S07. Otherwise, the process proceeds to step S09.

<Step S07: Determination of oxygen concentration>
The ECU 100 determines whether or not the oxygen concentration in the exhaust gas detected by the A / F sensor 103 is equal to or higher than a preset threshold value.
The threshold value is set in consideration of the fact that an oxygen amount sufficient for PM combustion can be supplied to the DPF 80 during the regeneration operation.
If the oxygen concentration is greater than or equal to the threshold value, the process proceeds to step S08; otherwise, the process proceeds to step S09.

<Step S08: Reproduction suitability determination is established>
The ECU 100 establishes the regeneration suitability determination on the assumption that the current operating state of the engine 10 is a state suitable for regeneration of the DPF 80 (a state in which the DPF 80 can be regenerated with a relatively small post injection amount).
Then, it progresses to step S10.

<Step S09: Reproduction nonconformity determination is established>
ECU 100 assumes that the current operating state of engine 10 is not suitable for regeneration of DPF 80 (a state in which a relatively large amount of post-injection is required for regeneration of DPF 80, or a state in which regeneration is substantially impossible). The reproduction nonconformity determination is established.
Then, it progresses to step S11.

<Step S10: Reproduction determination counter value addition>
The ECU 100 adds a counter value that counts the number of times that the regeneration suitability determination is established within the immediately preceding predetermined period (for example, about several seconds to several tens of seconds).
Note that counter values added in the past before a predetermined period are sequentially erased (cleared).
Then, it progresses to step S11.

<Step S11: Judgment of cumulative counter value>
The ECU 100 determines whether or not the accumulated value of the counter values added within a predetermined period (accumulated counter value) is equal to or greater than a preset threshold value.
If the cumulative counter value is greater than or equal to the threshold value, it is determined that the reproduction suitability determination has been established with high frequency, and the process proceeds to step S12. In other cases, the establishment frequency of the regeneration suitability determination is assumed to be low, and the process returns to step S01. Repeat the subsequent steps.

<Step S12: Execution of regeneration operation>
The ECU 100 determines to execute the regeneration operation of the DPF 80 even when the estimated PM accumulation amount is equal to or less than the first threshold value, and causes the fuel supply apparatus 50 to start post injection.
The post-injected fuel is combusted in the DOC 70 to improve the exhaust temperature.
The heated exhaust gas flows into the DPF 80 from the DOC 70 to improve the temperature in the layer, and ignites the PM to start the regeneration process.
Thereafter, the series of processes is terminated (returned).

According to the embodiment described above, the following effects can be obtained.
(1) By establishing regeneration suitability determination only when the exhaust gas flow rate is within a range between a predetermined upper threshold value and lower threshold value, the exhaust gas flow rate is excessive or too small so that the inside of the layer during DPF regeneration It is possible to prevent the temperature controllability from deteriorating and to efficiently regenerate the DPF 80 with a small post injection amount.
Thereby, mixing of the fuel into the oil can be suppressed, and dilution of the oil can be prevented.
(2) Only when the oxygen concentration in the exhaust gas is equal to or higher than the threshold value, the regeneration suitability determination is established, so that the regeneration operation is performed in a state where oxygen necessary for oxidation of unburned fuel in the DOC 70 and soot oxidation in the DPF 80 is insufficient. It is possible to prevent post-injection that has been started and does not substantially contribute to regeneration of the DPF 80 from being performed wastefully. (3) The fuel that has been post-injected by establishing the regeneration conformity determination only when the exhaust temperature is equal to or higher than the threshold value Can be reliably oxidized (combusted) in the DOC 70 to raise the exhaust gas temperature, and the DPF 80 can be reliably regenerated.
(4) The state in which the regeneration operation of the DPF 80 is executed only when the regeneration suitability determination is established is high, and the regeneration operation is started, for example, at the time of temporary sudden acceleration. Thus, the situation where the regeneration efficiency is deteriorated can be avoided, and the effective regeneration operation can be surely performed.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The configurations of the engine and its auxiliary devices are not limited to the above-described embodiments, and can be changed as appropriate.
(2) In the embodiment, when the frequency at which the regeneration suitability determination is established is equal to or higher than a predetermined value, the regeneration operation is performed even when the PM accumulation amount is relatively small. Alternatively, or in combination with this, the minimum time for performing reproduction may be switched to a low value.
(3) The conditions for establishing the reproduction suitability determination are not limited to those in the embodiment, and can be appropriately changed, added, deleted, and the like.

DESCRIPTION OF SYMBOLS 10 Engine 11 Crankshaft 12 Piston 13 Cylinder block 13a Crank angle sensor 13b Water temperature sensor 14 Head 15 Combustion chamber 16 Glow plug 17 Glow controller 20 Turbocharger 21 Compressor 22 Turbine 23 Actuator 24 Negative pressure control valve 30 Intake system 31 Intake duct 32 Air cleaner 33 Air Flow Meter 34 Intercooler 35 Throttle Valve 36 Actuator 37 Intake Chamber 38 Intake Pressure Sensor 39 Intake Manifold 40 Exhaust System 41 Exhaust Manifold 42 Exhaust Pipe 50 Fuel Supply Device 51 Supply Pump 52 Suction Metering Solenoid Valve 53 Fuel Temperature Sensor 54 Common Rail 55 Fuel pressure sensor 56 in Ekuta 60 EGR device 61 EGR passage 62 EGR control valve 63 EGR cooler 70 oxidation catalyst (DOC) 71 Temperature sensor 80 diesel particulate filter (DPF)
81 Differential pressure sensor 82 Temperature sensor 100 Engine control unit (ECU)
101 Accelerator pedal sensor 102 Atmospheric pressure sensor 103 A / F sensor

Claims (5)

An oxidation catalyst and a particulate matter filter sequentially arranged from the upstream side to the exhaust pipe of the engine;
An exhaust purification device comprising: regeneration propriety determination means for determining the propriety of the regeneration operation for performing regeneration of the particulate matter filter by causing the fuel injection device of the engine to perform post injection,
Load detection means for determining the load state of the engine;
Climbing judgment means for judging the climbing state of the vehicle;
An exhaust flow rate detecting means for detecting the exhaust flow rate of the engine,
The regeneration suitability determining unit is configured such that the load detecting unit determines a predetermined high load condition , the climbing determination unit determines the climbing state, and the exhaust flow rate is between a predetermined upper limit side threshold and a lower limit side threshold. When it is in the range, it is determined that the state is suitable for the regeneration operation.   An oxidation catalyst and a particulate matter filter sequentially arranged from the upstream side to the exhaust pipe of the engine;
  Regenerative propriety determining means for determining the propriety of the regenerating operation for regenerating the particulate filter by causing the fuel injection device of the engine to perform post injection;
  An exhaust purification device comprising:
  Load detection means for determining the load state of the engine;
  High-speed traveling determination means for determining a high-speed traveling state of the vehicle;
  An exhaust flow rate detecting means for detecting the exhaust flow rate of the engine,
  The regeneration suitability determining unit is configured such that the load detecting unit determines a predetermined high load condition, the high speed traveling determining unit determines the high speed traveling state, and the exhaust flow rate is a predetermined upper limit side threshold value and a lower limit side threshold value. To determine that it is in a state suitable for the regeneration operation when it is within the range between
  An exhaust purification device characterized by the above. Oxygen concentration detection means for detecting the oxygen concentration in the exhaust gas upstream of the oxidation catalyst,
The exhaust emission control device according to claim 1 or 2 , wherein the regeneration suitability determination unit determines that the state is suitable for the regeneration operation when the oxygen concentration is equal to or higher than a predetermined value. An exhaust temperature detecting means for detecting the exhaust temperature is provided,
The reproduction appropriateness determination means, the exhaust gas temperature according to any one of claims 1, wherein the determining that the state suitable for the regeneration operation in the case of a predetermined value or more to claim 3 Exhaust purification device. The regeneration operation execution means for executing the regeneration operation when the frequency at which the regeneration suitability determination means determines that the regeneration suitability is in a state suitable for the regeneration operation is equal to or greater than a predetermined value within a predetermined period. The exhaust emission control device according to any one of claims 1 to 4 .

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